Neodron LTD v. Hewlett Packard Enterprise Company

Western District of Texas, txwd-6:2019-cv-00319

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0 Exhibit 3 Case 6:19-cv-00319-ADA Document US008791910B2 (12) United States Patent Philipp (10) Patent No.: (45) Date of Patent: US 8,791,910 B2 Jul. 29, 2014 (54) CAPACITIVE KEYBOARD WITH POSITION-DEPENDENT REDUCED KEYING AMBIGUITY (75) Inventor: Harald Philipp, Hamble (GB) 6,466,036 B1 6,677,932 B1 6,993,607 B2 7,336,206 B2 7,663,607 B2 7,875,814 B2 7,920,129 B2 8,031,094 B2 8,031,174 B2 8,040,326 B2 10/2002 Philipp 1/2004 Westerman 1/2006 Philipp 2/2008 Sugimara 2/2010 Hotelling 1/2011 Chen 4/2011 Hotelling 10/2011 Hotelling 10/2011 Hamblin 10/2011 Hotelling (Continued) (73) Assignee: Atmel Corporation, San Jose, CA (US) (*) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 187 days. FOREIGN PATENT DOCUMENTS (21) Appl. No.: 13/043,231 DE (22) Filed: Mar. 8, 2011 EP wo 1970 02 225 C1 5/1998 1 381 160 A11/2004 WO 2012/129247 9/2012 OTHER PUBLICATIONS (65) Prior Publication Data US 2011/0157085 A1 Jun. 30, 2011 Office Action and English Translation for German Patent Application 10 2007 024 455.1, Dec. 7, 2011. (Continued) Related U.S. Application Data (63) Continuation of application No. 11/750,430, filed on May 18, 2007, now Pat. No. 7,903,092. (60) Provisional application No. 60/803,138, filed on May 25, 2006. Primary Examiner — Waseem Moorad (74) Attorney, Agent, or Firm — Baker Botts LLP (52) (51) Int. Ci. GO6F 3/041 (2006.01) U.S. CI. USPC ...... 345/173 (58) Field of Classification Search USPC ........... ............ 341/22–33; 345/173-179 See application file for complete search history. .... (57) ABSTRACT In one embodiment, a method includes receiving two or more output signals responsive to two or more capacitive cou- plings. Each of the capacitive couplings has occurred between a pointing object and one of two or more sensing areas within a sensing region, and each of the sensing areas has a position within the sensing region. The method includes, if two or more of the output signals each have an output-signal level that exceeds a predefined activation level, then selecting a particular one of the sensing areas with out- put-signal levels exceeding the predefined activation level as an intended one of the sensing areas based on a predefined ranking scheme that takes into account the positions of the sensing areas within the sensing region. (56) References Cited U.S. PATENT DOCUMENTS 710/67 5,730,165 A 5,734,928 A * 5,748,512 A 6,452,514 B1 3/1998 Philipp 3/1998 Nakasuji 5/1998 Vargas 9/2002 Philipp 37 Claims, 5 Drawing Sheets 11223 43] 54 63 758895 0 US 8,791,910 B2 to be the selected sensing area by taking account both the down 'losing' process over the winning process, in order to output signals associated with the sensing areas and the posi facilitate better suppression of noise. The rate of counting tions of the sensing areas within the sensing region. down any of the DI counters can also be the complete value, The method may further comprise outputting an output i.e., the DI can be cleared in one cycle. In this embodiment, signal indicative of the sensing area determined to be the 5 when two or more keys have signal strengths above their selected sensing area. nominal thresholds, the key with the lesser signal strength Other aspects and features of the invention are as follows. will have its associated DI decremented or cleared each cycle One aspect of the invention is that it may provide a method while this condition exists. If any two or more keys have equal of removing keying ambiguity by measuring a detected signal and maximal signal strengths, such keys' DI's will continue associated with each key in an array, comparing the measured 10 to increment until the first to reach its TC 'wins' and is set as signals, determining that an upper key having a signal in the unique user-selected key. relation to a lower key signal is the unique user-selected key, In another embodiment, the DI of a key selected at a first and maintaining that selection until either the upper key's instant may be decremented or cleared and that key dese- signal strength drops below some threshold level or a second lected even if the signal strength of that key is above the key's signal strength exceeds the upper key's signal strength. 15 threshold value and its DI equals its associated TC value, if When an upper key and a lower key are pressed by a user, the second key becomes selected at a later instant by virtue of its upper key is preferentially selected and its signal strength signal strength being greater than the signal strength of the value may be enhanced relative to the other key(s) so as to first key while also being above its own threshold value and deselect the other key(s). In this aspect, the array under con- having its associated DI equal its associated TC. If there are sideration may be a keyboard, or any convenient subset 20 multiple keys with signal strengths above their associated thereof. threshold values, their associated Dis will count up and down The present invention provides an improvement over U.S. in competition, until one key's DI finally equals its TC and Pat. No. 6,466,036 and U.S. application Ser. No. 11/279,402 wins over all others including over the previously selected (published as US 2006-0192690 A1) in that an upper key of a key. keypad can be preferentially selected over a lower key or keys 25 In the above discussions, it should be understood that the even if the signal from the upper key is weaker than the signal principle of having one signal greater than another has been from the lower key or keys. This is particularly advantageous somewhat simplified for explanatory purposes. In order to for small keyboards or keypads, like mobile phones which are avoid indecisiveness and eliminate oscillation between two or becoming increasingly smaller in size with improvements in more keys having more or less the same signal strengths, the technology and due to consumer demand requiring ever more 30 winning key may preferably be given a slight advantage in miniature and 'slim' handsets. With small mobile handsets subsequent repetitions of the decision process. This may be the keys can be spaced very closely together which means that done, for example, by requiring a non-selected key's signal to it is difficult to press the intended keys, especially if the user exceed the currently selected key's signal by a small amount. has large fingers. Often a user may accidentally press more This can be done by subtracting a small amount off the signals than one key at the same time including the intended key the 35 of non-selected keys, or by adding a small amount onto the user wished to select. The invention allows an upper key to be selected key's signal. selected by suppressing the signal from other adjacent keys In an embodiment, if the signal strengths of two keys that that may also have been pressed or from which capacitive are approaching a detection threshold value and that are both ing may have been detected, as the upper key is often the in a defined keyboard neighborhood both exceed the thresh- intended key of the user. 40 old value and their signal strengths are equal to each other (or The invention may be used in combination with the teach- are within a selected tolerance value) at the same time, an ing of U.S. Ser. No. 11/279,402 (published as US 2006 algorithm executed by a controller may be used to declare one 0192690 A1), although when it is recognised that there is a of the two keys to be active and the other to be inactive. It will signal associated with an upper key and a signal associated be recognized that a wide variety of algorithms are possible with a lower key on a keypad, the upper key may be prefer- 45 and include, but are not limited to, a random, or pseudo- entially selected over the lower key. Therefore, the present random selection of the active key, or a declaration of activity invention may be referred to as "position-dependent' key based on which key was scanned first. In an alternative ambiguity reduction and this may override the detection inte embodiment, if two keys exceed the threshold value and their grator counter (DI) system disclosed in U.S. Ser. No. 11/279, signal strengths are equal to each other at the same time, an 402 (published as US 2006-0192690 A1) when touch from a 50 algorithm executed by a controller may be used to cancel the group of keys is capacitively detected and there is an upper/ signal from both keys until the user presses the intended key lower key relationship between the keys. again so that one signal can be identified as having a maxi- U.S. Ser. No. 11/279,402 (published as US 2006-0192690 mum signal strength. Al) discloses an embodiment with an array of capacitive keys Those skilled in the keyboard arts will understand that the in which each key has a respective detection integrator 55 above-mentioned neighborhoods can be defined in a wide counter (DI) associated with it. Each DI is a clocked counter variety of ways. In some cases, a neighborhood of a given key that counts up by one incremental value on each capacitive may consist of the keys immediately adjacent the given key, acquisition cycle during which a signal strength from the or may comprise the keys having no more than one key associated key is above some nominal threshold value, and between them and the given key. In other cases, the neighbor- that counts down toward zero if the signal strength is less than 60 hood may comprise all the keys in a matrix array-e.g., in a the nominal value. A controller receives a respective input keyboard for use in a numerical data entry application in from each DI and determines that one of the keys is selected, which only one key is to be active at a time so that the e.g., wins, when the detection integration (DI) count associ sequence of input digits is uniquely determined. In other ated with that key meets a respectively selected terminal cases, such as in a typing or computer-input keyboard, the count value, TC. The incremental magnitude used for count- 65 neighborhood of a key may comprise all other keys in the ing down can be the same as that for counting up, e.g., 1, or it k eyboard except for special purpose keys, such as a capitali- can be different, e.g., 2, to preferentially accelerate the count zation shift key, a control key, and the like. Moreover, a Рperi 0 US 8,791,910 B2 Pu keyboard may be configurable by a user who programs a shown in FIG. 1 is a pointing object 110, in this case a user's controller to selectively consider or ignore various keys in an finger, approaching the keypad to select one of the keys. array. In some cases there might be two neighborhoods, each The keypad 102 may be of conventional design. In this acting independently of the other for key ambiguity resolu- embodiment the keypad is formed of a plastic substrate hav- tion purposes. 5 ing discrete areas of conductive material deposited on the Although it is believed that the foregoing rather broad underside thereof to provide sensing electrodes. The shapes summary description may be of use to one who is skilled in and locations of the electrodes define the shapes and locations the art and who wishes to learn how to practice the invention of the corresponding sensing areas of the keyboard/keypad. it will be recognized that the foregoing recital is not intended The sensing electrodes are coupled to respective ones of a to list all of the features and advantages. Those skilled in the 10 plurality of capacitance measurement channels 106 in a art will appreciate that they may readily use both the under capacitance measurement circuit. The capacitance measure- lying ideas and the specific embodiments disclosed in the ment channels are for measuring the capacitive coupling of following Detailed Description as a basis for designing other the associated electrodes to a system reference (ground) arrangements for carrying out the same purposes of the potential, and generating corresponding output signals C1-12 present invention and that such equivalent constructions are 15 indicative of the measured capacitances. The capacitance within the spirit and scope of the invention in its broadest measurement channels may be of any known kind. For form. Moreover, it may be noted that different embodiments example circuitry based on RC circuits, relaxation oscillators, of the invention may provide various combinations of the phase shift measurements, phase locked loop circuitry, or recited features and advantages of the invention, and that less capacitive divider circuitry may be used. In this example the than all of the recited features and advantages may be pro- 20 capacitance measurement channels are based on charge trans- vided by some embodiments. fer techniques, such as those described in U.S. Pat. No.5,730, It will be appreciated that features described above in con- 165 or U.S. Pat. No. 6,466,036. Here separate capacitance nection with one aspect of the invention will often be equally measurement channels are provided for each key in the key- applicable to, and may be combined with, other aspects of the pad. However, in other embodiments fewer capacitance mea- invention. 25 surement channels, e.g. a single channel, may be used with appropriate multiplexing. BRIEF DESCRIPTION OF THE DRAWINGS The UI 100 further includes a controller 108. The control- ler is for receiving the output signals C. from the capaci- For a better understanding of the invention and to show tance measurement channels and determining from the how the same may be carried into effect reference is now 30 received output signals which (if any) of the keys is selected made by way of example to the accompanying drawings in by a user, and outputting a corresponding key-selection out- which: put signal O/P. The key-selection output signal O/P may then FIG. 1 schematically shows in perspective view a touch be passed to and acted upon as appropriate by a main control- sensitive user interface (UI) according to an embodiment of ler of the device associated with the UI in the normal way. The the invention; 35 controller functionality may be provided by a suitably pro- FIG. 2 schematically shows in plan view a sensing region grammed general purpose processor, for example, or by portion of the UI shown in FIG. 1; means of special purpose hardware. For example the control- FIG. 3 schematically shows a priority ranking scheme for ler 108 may comprise a suitably configured application spe- keys of the keypad shown in FIGS. 1 and 2 according to an cific integrated circuit (ASIC), a field programmable gate embodiment of the invention; 40 array (FGPA), or an arrangement of discrete components. FIGS. 4 and 5 schematically show priority ranking The keypad in this example corresponds in layout with that schemes for keys of the keypad shown in FIGS. 1 and 2 of a typical telephone. Thus the twelve sensing areas (keys) according to other embodiments of the invention; 104 are respectively associated with the numbers 0 to 9, and FIG. 6 schematically shows in plan view a sensing region the symbols * (star) and # (hash), as indicated in the figure. portion of the UI shown in FIG. 1 with shading used to 45 The sensing region is overlain with graphic decals to indicate indicate three separate key groupings; to a user the shape and location of the underlying electrodes FIGS. 7 and 8 show an array of tightly spaced capacitive which define the sensitive areas of the keys, and also their buttons; associated functions. To select a desired key, a user moves his FIGS. 9(a) and 9(b) are graphical representations of signal finger towards the appropriate part of the sensing area (as magnitude associated with respective keys shown in FIG. 8 50 indicated to him by the graphic decal overlay), so that his caused by capacitive coupling with a finger; finger is brought into proximity with the corresponding elec- FIG. 10 schematically shows a mobile phone handset hav trode. This act of selecting a key will sometimes be referred to ing an array of tightly spaced capacitive buttons; and as "pressing" a key. However, it will be understood that the FIG. 11 schematically shows a keypad of a mobile phone term is used for convenience, and should not be interpreted as handset. 55 necessarily implying any form of physical contact between the pointing object and the selected sensing area. DETAILED DESCRIPTION OF PREFERRED In FIG. 1, the user is shown selecting the key associated EMBODIMENTS with the number 7. The proximity of the user's finger to the electrode associated with number 7 increases the capacitive FIG. 1 schematically shows in perspective view a touch 60 coupling of the electrode to ground. This leads to a change in sensitive user interface (UI) 100 according to an embodiment the output signal from the associated capacitance measure- of the invention. The UI comprises a sensing region 102 ment channel. Depending on the nature of the capacitance having an array of discrete capacitive sensing areas 104. In measurement channels used, an increase in capacitive cou- this example there are twelve sensing areas arranged in a pling may lead to either an increase in output signal (direct three-by-four array. The sensing region 102 may conve- 65 relationship) or a decrease in output signal (inverse relation- niently be referred to as a keyboard or keypad and the sensing ship). For simplicity, and unless the context demands other- areas 104 may conveniently be referred to as keys. Also wise, references to an increased output signal should be read 0 US 8,791,910 B2 10 throughout this description as meaning a change in the output telephone such that the plane of the keypad is arbitrary (e.g. signal which indicates an increase in the measured capacitive horizontal). Similarly, the column containing keys "1", "4", coupling of the associated electrode to ground, irrespective of "7" and "*" may be referred to as a leftmost column of the whether there is a direct or an inverse relationship between the keypad, and the column containing keys "3", "6", "I" and "#" measured capacitance and the output signal (i.e. irrespective 5 may be referred to as a rightmost column of the keypad. of whether parameterization of the output signal employed by FIG.2 schematically shows in plan view the sensing region the type of capacitance measurement channel goes up or portion 102 of the UI shown in FIG. 1 with the user's finger down in response to an increase in measured capacitance). 110 shown in a position in which he intends to select key "1". The controller is operable to determine if the characteristics The user's finger is sufficiently close to the intended key "1" of an increase in measured capacitance (e.g. magnitude, dura- 10 that the change in output signal C, associated with this key is tion) are such that the key should be deemed to be in an such that the controller determines the key to be activated. activated state. This can be done according to conventional This is schematically shown in the figure by shading of the techniques, for example by requiring a predefined activation key "1". The user's finger also increases the output signal output signal level to be exceeded, and furthermore may from the other keys in the keypad, most notably keys "2", "5" employ techniques such as thresholding, drift compensation, 15 and "4". Here it is assumed that ke filtering etc. affected. This is because key"4" is located below the intended Thus, referring to FIG.1, the proximity of the user's finger key, and so the direction of extent of the user's finger runs to the desired key, here key"7", increases the output signal CZ directly over this key (handshadow). It is thus assumed that associated with the key by an amount that leads the controller key "4" is also deemed to meet the requirements for being to determine that key "7" is activated (e.g. because the output 20 considered activated. Key "4" is thus also shown shaded in the signal has remained changed by a large enough amount for a figure. Keys "2" and "5" are assumed in this case not to be long enough period). However, as noted above, it will gener sufficiently affected to be deemed activated and so are not ally be the case that the presence of the user's finger 110 shaded in FIG. 2. In this situation (at least for cases in which adjacent to the sensitive area of the desired key "7" will also only one key may be determined as being selected at any one cause an increase in the capacitive coupling to ground of 25 time) the controller needs to decide which of keys "1" and "4" neighboring keys within the sensing region due to the prox is to be taken as being intended for selection by the user so that imity of the user's finger to these keys also. What is more, the an appropriate key selection output signal O/P from the UI increase in output signal associated with the keys not intended can be generated. for selection may be sufficient for the controller to determine In a conventional touch sensitive user interface, the choice that the output signals from these keys also meet the require- 30 of which of keys "4" and "1" should be taken as being the ments for being considered activated. Thus for the case shown user-selected key (i.e. the key intended for selection by the in FIG. 1, the output signals associated with keys "4", "5", user) will typically be based on either the magnitude of the "8", "O", and "*" might also show significant increases in output signals associated with the two keys (i.e. the key dis- response to the approach of the user's finger, and may thus playing the greatest output signal is deemed to be the selected appear to be activated. The "*" key is likely to be most 35 key), or based on timing (i.e. the key which becomes activated significantly effected because in addition to the user's finger first is deemed to be the selected key). However, both of these tip being near to this key, the main body of the user's finger is approaches can readily lead to incorrect determinations. For also located over it (handshadow). Because of this the "*" key example, although in FIG. 2 the user intends to select key"1", may even show a greater change in output signal than key"7". the change in output signal Ca associated with key" The following describes how the controller 108 for the UI 40 in fact be larger. This could be due to the additional capacitive shown in FIG. 1 is operable to determine which key is to be coupling provided by the main body of the user's finger to taken as being intended for selection by the user when mul ground (handshadow), or simply because key "4" is more tiple keys show a sufficient increase in output signal that they sensitive than key"1". Touch sensitive keys in an array will in meet the requirements for being considered activated accord general have differing sensitivities. Differences in sensitivity ing to one embodiment of the invention. 45 can be caused both by manufacturing tolerances and environ- A consideration in determining the most likely one of mental effects (e.g. one key might be nearer to a ground plane, multiple simultaneously activated keys intended for selection which will tend to reduce its sensitivity). Furthermore, ments of the invention is the although the user intends to select key "1", the characteristics orientation of the sensing region (keypad) relative to the of the change in output signal C4 associated with key "4" may normal direction of approach of a pointing object during 50 be such that key "4" is deemed to be activated (goes into normal use. For simplicity, terms such as upper, lower, left, activation) first. E.g., because in selecting key "1" the user's right, etc. are used here to describe the relative positions of finger first moves over key "4". Thus conventional key-selec- keys in the sensing region according to an orientation in tion schemes based on magnitude or timing can both readily which a direction of extent of a pointing object, which will lead to an incorrect determination of the intended key. generally also correspond to an approach direction, is sub- 55 User interfaces according to embodiments of the invention stantially parallel to a direction running from a lower part to overcome this problem by taking account of both the output an upper part of the keypad. Thus for a mobile (cellular) signals from the keys in the keypad and their positions within telephone keypad such as shown in FIG. 1, a user will nor the keypad when determining a user selected one of the sens- mally select keys with his finger approaching from a direction ing areas (i.e. the intended key). This may be achieved by substantially parallel to the columns and running from the 60 preferentially selecting from the activated keys according to row containing keys "*", "O" and "#" to the row containing the position of the keys in the keypad, i.e. by assigning a keys "1", "2" and "3" (as schematically shown in FIG. 1). priority to each key in the keypad according to its position, Thus the row containing keys "*", "O" and "#" may be and preferentially selecting keys having higher priorities. referred to as a lowermost (bottom) row of the keypad, and the FIG. 3 schematically shows a priority ranking scheme for row containing keys "1", "2" and "3" may be referred to as an 65 keys of the keypad shown in FIGS. 1 and 2 according to an uppermost (top) row of the keypad. This terminology will be embodiment of the invention. For each key the priority rank is used notwithstanding the fact that the user may hold the shown as a superscript to the symbol associated with the key 0 US 8,791,910 B2 11 function. Thus all of the keys on the uppermost (top) row are a priority ranking according primarily to their row, but also assigned a priority rank 1. These are the highest priority keys, according to their column. Thus keys in the top row are ranked the keys being of equal priority to one another. The keys "4", higher than keys in the next row down, which themselves are "5 and "6" are all assigned priority rank 2. Keys "7", "8 and ranked higher than keys in the next row down, and so on. "9" are assigned priority rank 3. Finally the keys on the lowest 5 Furthermore, within each row, keys in the left column are row (relative to an approaching finger) are assigned the lowest ranked higher than keys in the centre column, and keys in the priority rank 4. centre column are in turn ranked higher than keys in the right In determining which of a plurality of keys deemed to be in column. This ranking scheme may be more appropriate for a simultaneous activation is to be taken as being the user keypad for which in normal use a pointing object approaches intended key for selection, the controller is operable to take 10 from the lower right of the keypad (for the orientation shown account of the relative priority ranking of the activated keys. in FIG. 4). This might be the case, for example, for a mobile of doing this is in an absolute manner, e.g. in telephone keypad with a predominantly right-handed user which the highest ranked key in activation is deemed to be the E.g. the user may cradle the telephone in the palm of his right selected key (in the case of multiple selected keys of the same hand and use his thumb as a pointing object, or hold the highest rank, the key having the highest rank and greatest 15 telephone in his left hand and use his right forefinger as a output signal, or the key having the highest rank to have gone pointing object. In both of these cases there is an increased into activation first, may be selected, for example). Thus risk that keys to the right of an intended key will have their referring to FIGS. 2 and 3, keys "l" and "4" are in activation. output signals unduly increased by the user's thumb/finger- Key "1" has a ranking of 1 and key 4 has a ranking of 2. Thus tip being relatively near to them and the body of the thumb/ key "1" is deemed to be the user-intended key for selection 20 finger passing over them. Thus keys towards the left-hand because it is of higher priority (rank 1) than key"4" (rank 2). side of the keypad are assigned priority rankings (indicated by Another way in which the controller may take account of a higher numerical superscript in the figure) than keys the relative priority ranking for the activated keys is by output towards the right-hand side of the keypad. (A left-right rever- signal weighting to preferentially select keys at positions sal of this ranking scheme may be better for a keypad to be associated with higher rankings. Thus the controller may be 25 used predominantly by a left-handed user. The UI may thus be arranged to apply a weighting to the output signals according configured to allow the user to select between ranking to the positions of the corresponding keys in the sensing schemes). region. For example, a scale factor may be associated with FIG. 5 is similar to and will be understood from FIGS. 3 each priority rank (i.e. so that each key is associated with a and 4. For the ranking scheme represented in FIG. 5, the keys predefined scale factor) and keys associated with higher scale 30 are again assigned a priority ranking according primarily to factors may be preferentially selected over keys having lower their row, and as with FIG. 4 are also prioritized according to scale factors. For example, and again referring to FIGS. 2 and their column. However, the rankings according to column are 3, a priority rank of 1 might be associated with a scale factor different from those of FIG. 4. The row ranking is broadly the of 2, a priority rank of 2 might be associated with a scale same in that keys in the top row are ranked higher than keys in factor of 1.5, a priority rank of 3 might be associated with a 35 the next row down, which themselves are ranked higher than scale factor of 1.0, and a priority rank of 4 might be associated keys in the next row down, and so on. However, within each with a scale factor of 0.5. Thus for the case shown in FIG. 2, row, keys in the left column and right column are ranked equal the output signals of the activated keys are scaled in accor and higher than keys in the centre column. This ranking dance with their respective predefined scale factors. The key scheme may be preferred for a keypad for which in normal use having the highest weighted output signal is then deemed to 40 a pointing object approaches from either the lower left or the be the selected key. This has the advantage over the above lower right of the keypad (for the orientation shown in the described absolute priority ranking scheme in that a lower figure). This might be the case, for example, for a mobile ranked key can still be selected over a higher ranked key if its telephone keypad which may be used with either left-handed output signal is sufficiently high compared to that of the or right-handed users, or for a device held between the palms higher-ranked key (i.e. the lowest ranked keys are not too 45 of both hands with both thumbs being used as pointing strongly blocked out from selection). objects. The principle underlying the ranking scheme shown In some examples based on output signal weighting there in FIG. 5 is that if a pointing object approaches from the right may not be a step of first determining which keys are in and intends to select key "4", key "g" is less likely to be activation. Instead the output signals from all keys may be wrongly reported as the selected key because it is suppressed scaled by their appropriate predefined scale factors and key 50 by virtue of its lower ranking. Key"6", on the other hand, has having the greatest weighted output signal taken to be the the same ranking as key"4". However, key "6" will in general selected key. (Possibly after first determining that the greatest be less likely to be wrongly selected if a user intends to select weighted output signal meets predefined requirements for key"4" because it will be further away from his finger tip and, reporting a selection, such as magnitude and duration of so will be expected to display a significantly lower output signal, to avoid the controller reporting a selected key when 55 signal (i.e. there is less chance of a non-immediate neighbor the keypad is not in fact in use.) key being wrongly selected than for an immediate neighbor FIG. 4 is similar to and will be understood from FIG. 3. key. Thus it is not so significant that it has the same ranking). However, FIG. 4 shows an alternative ranking scheme for the The same applies for a pointing object approaching from the keys of the keypad shown in FIGS.1 and 2. As with FIG. 3, for left and intending to select key "6" (i.e. key "5" is suppressed priority rank is shown as a superscript 60 by virtue of its lower ranking, and key "4" will be unlikely to to the symbol associated with the key function. The ranking be selected because of its greater distance from the user scheme shown in FIG. 3 and described above may be most intended key "6"). appropriate for a keypad for which in normal use a pointing As will be readily understood, the specific details of any object approaches from, and extends along, a direction which given priority ranking scheme, e.g. the appropriate scale fac- is substantially parallel with the columns of the keys. Thus 65 tors or absolute rankings for the different keys, will depend on keys in the same row are assigned equal priorities. However, the specific keyboard layout at hand, the relative sizes of the for the ranking scheme shown in FIG. 4, the keys are assigned keys, the spacing between them relative to the size and shape 0 14 US 8,791,910 B2 13 of the pointing object, the normal orientation of the keyboard order or in parallel.) Thus with this approach the UI may be in use, and the nature of the pointing object, and the direction considered as three separate and independent sensing regions. in which the pointing object normally moves towards and The result is therefore three independently selected (interme- over the keyboard when selecting a key. The specific details of diate) keys, one from each group. (It is assumed here that the ranking scheme can thus be determined experimentally by 5 there is at least one key in each group having output signal identifying which keys during normal use of a particular characteristics to meet the requirements for being considered keyboard layout have a tendency to be wrongly selected when in activation. However, in many cases it may be that there is no ranking scheme being used, and providing these keys with no key within a group that can be considered in activation and an accordingly lower ranking to suppress them. thus a null-result (no key deemed selected) may be deter- For example, consider a keyboard having 3 keys "A", "B" 10 mined for that particular grouping of keys.) and "C". In an experiment the keys are equally ranked and a The next stage is to determine which of the three interme- user presses each key 100 times in the manner expected during normal use (i.e. approaching the keypad with the nor- diate independently selected keys is to be determined as the mal pointing object from the normal-use direction). Because sole user-selected key. This may be done in a number of ways, of the above-mentioned problems with determining a correct 15 15 for example, based on known techniques for selecting key selection it is assumed the controller wrongly determines between multiple keys (e.g. greatest output signal, first to go that key "A" is selected 150 times, key "B"100 times, and key into activation, etc.). Alternatively, the selection may be made "C" 50 times. In view of these statistics, the keys may thus be in a manner similar to the scheme used to select the keys from signal from key "A" is scaled by within the separate groupings (i.e. by taking account of the factor of two-thirds, the output signal from key "B" is scaled 20 positions of the keys selected in the first stage within the UI as by factor of unity, and the output signal from key "C" is scaled a whole, possibly with the keys having different priority rank- by factor of two, for example. ings in this stage compared to the first stage). FIG. 6 schematically shows in plan view the sensing region The preceding description, in particular with reference to portion of the UI shown in FIG. 2. FIG. 6 is thus similar to and FIG. 1, has focused on capacitive sensors based on what will be understood from FIG. 2. However, portions of the UI 25 might be termed passive sensing techniques, i.e. sensors in shown in FIG. 6 are overlain with shading to represent some which all of the electrodes defining the sensing areas in the predefined key groupings (in this case three) which may be sensing region are individually responsive to a capacitive used in embodiments of the invention. The key groupings coupling between a pointing object and respective ones of the shown by the shading do not mean that the grouped keys share sensing areas (i.e. sensors of the type described in U.S. Pat. any particular characteristics which are different from keys in 30 No. 5,730,165 and U.S. Pat. No. 6,466,036). However, other groups, rather the groupings are notional and merely embodiments of the invention may also be based on what represent collections of keys which may be considered might be termed active capacitive sensing techniques, e.g. together and independently of other keys for some aspects of sensors in which sensitive areas are based on paired drive and the process of determining a selected key according to some receive electrodes (such as described in U.S. Pat. No. 6,452, embodiments of the invention. As indicated in FIG. 6, keys 35 514). The drive and receive electrodes may be arranged in a "1", "4", "7" and "k" collectively form a first group of keys, matrix array where keys (sensing areas) are defined by over- keys "2", "5", "X" and "O" collectively form a second group of lap regions between row and column electrodes. With this keys, and keys "3", "6", "9" and "#" collectively form a third type of sensor, changes in a capacitive coupling between a group of keys. The inventors have found that improved reli pointing object and respective ones of the sensing areas ability in key selection can be obtained if the process of 40 modify the transfer of a drive signal from the drive electrode determining a user intended key is performed in two stages. In to the receive electrode. a first stage the most likely key within each of the predefined Furthermore, although the above description has focused groups is determined, for example, using the principles on user interfaces comprising physically discrete sensing described above whereby keys are preferentially selected areas, embodiments of the invention may be based on a user according to their position within the group, and in a second 45 interface having a continuous 2-D sensing region in which stage, the overall most-likely key of the most-likely keys from "virtual" sensing areas are defined. For example, a continuous each group is determined. 2-D region may be notionally divided into an array of virtual For example, with reference to FIG. 6, the controller first discrete keys. considers only the output signals from keys within the first It will also be appreciated that position sensors embodying group (i.e. keys "1", "4", "7" and "*"), and determines which 50 the invention may incorporate a variety of additional features. key within that group is to be deemed to be the selected key For example, in some applications it is desirable to have a for that group (independently of the output signals from keys 'wakeup' function, whereby the entire device 'sleeps'or is in in the other groups). This may be considered an intermediate some quiescent or background state. In such cases, it is often selected key. This is because although the key is selected from desirable to have a wake signal from mere proximity of a among the keys within the group, it may not be the finally 55 human body part some distance away. The element can be determined user-selected key from the keypad as a whole driven as a single large capacitive electrode without regard to since this may come from another group. The selection of the position location, while the unit is in the background state. intermediate selected key from each group may be done by During this state the electronic driver logic looks for a very taking account of the output signals and the positions of the small change in signal, not necessarily enough to process as a keys within the sensing region using any of the methods 60 2D coordinate, but enough to determine that an object or described above. In effect, in this stage the group of keys "1", human is in proximity. The electronics then 'wakes up' the "4", "7" and "*" is considered as a self-contained sensing overall system and the element is driven so as to become a true region containing only four keys which is independent of position sensor once again. other keys. The controller then does the same for the other two Also, although the term "touch" may be used in this groupings. These two groupings are also in effect self-con- 65 description, a position sensor of the kind described above can tained sensing regions. (It will be understood that the three be sufficiently sensitive that it is able to register the location of key-groupings could equally be considered in a different an adjacent finger (or other object such as a stylus) without 0 US 8,791,910 B2 15 се requiring physical contact. The term "touch" as used herein intersected key will receive due to the touch, although even should therefore be interpreted accordingly. non-touched keys will also see an increase in signal due to It will be appreciated that although particular embodiments mere finger proximity and to fringe-field effects within the of the invention have been described, many modifications/ touch panel. additions and/or substitutions may be made within the scope 5 In this case, the desire is to select the one and only one key of the present invention. Accordingly, the particular examples which is intended by the user while suppressing outputs from described are intended to be illustrative only, and not limita- adjacent keys intersected by the fingerprint. In this position- tive. Furthermore, it will be understood from the above dependent' key suppression invention, the output signal from description that features of embodiments of the invention upper key 12 is favoured over the signal from lower key 14, may be combined in ways other than those explicitly set out in 10 albeit in this case that the signal from key 12 is stronger than the appended claims. that from key 14. Referring to FIGS. 8 and 9, there is shown an array of Other Embodiments capacitive keys in a key panel 10 in which a fingerprint represented by outline 22 (in dashed lines) encompasses four In studying this description, the reader may be aided by 15 different keys 12, 14, 16, 18. The user's fingerprint 22 has a noting definitions of certain words and phrases used through centroid location A which is just above key 14 and between out this patent document. Wherever those definitions are pro keys 12,14. An output signal is measured from each of keys vided, those of ordinary skill in the art should understand that 12, 14, 16, 18, but the signal from key 14 has the maximum in many, if not most instances, such definitions apply to both strength because the fingerprint outline 22 encompasses the preceding and following uses of such defined words and 20 whole of key 14. As shown in FIG.9(a), the signal from each phrases. At the outset of this description, one may note that of keys 12 and 14 is above a threshold value. Key 14 would the terms "include" and "comprise," as well as derivatives initially be the favoured key. However, as shown in FIG.9(6) thereof, mean inclusion without limitation; the term "or," is in accordance with the invention, the output signal from key inclusive, meaning and/or. The word 'key' as generally used 14 is suppressed and the output signal from key 12 is in this disclosure refers to a touchable portion of a mechanical 25 enhanced, so that the upper key 12 'wins' and becomes the to electrical transducing device that is non-bistable in nature. user-selected key. In the invention, the signals from keys 14, This term specifically excludes conventional mechanical 16,18 can be suppressed and/or the signal from key 12 can be switches in which two or more electrical conductors are enhanced. Therefore, the invention allows an upper key (key moved into or away from contact with each other to make or 12 in FIG.8) having a weaker signal to become dominant with break an electrical connection. The terms 'keyboard', 'key- 30 respect to a lower key (key 14 in FIG. 8) having a stronger pad' and the like all refer to arrays of keys for data input signal, even if the measured signal from key 12 is below a without limitation as to the size or configuration of the array. threshold value. Signal enhancement can be directed to the A 'key' can also be a dimensional sensing surface such as an 'intended' key 12 due to the upper position of the key in the XY touch screen or a 'trackpad', or a sensing zone not region of keys that are touched. An algorithm may be intended for normal human data entry such as an object or 35 executed by a controller to enhance or activate the measured body part sensor. "Touch'can mean either human or mechani- signal from key 12. In an alternative embodiment, the keypad cal contact or proximity to a key. 'User' can mean either a comprising an array of capacitive keys may be in the form of human or a mechanical object. A 'finger' can be, inter alia, a a capacitive touch screen or touch pad. hanical finger or a stylus. 'Upper' key can Referring to FIG. 10, there is shown a mobile phone hand- mean a key in an upwardly spaced location with respect to 40 set 30 comprising an array of capacitive keys in a key panel another key on a keypad. 'Lower key can mean a key in a similar to that shown in FIG. 8. The cor downwardly spaced location with respect to another key on a FIG. 10 have the same reference numerals as those in FIG. 8. keypad. The output signal from key 12 (representing no. 5 on the key Capacitive sensors, unlike bistable electromechanical panel) is enhanced with respect to the signal from key 14 switches which are either open or closed, provide a signal that 45 (representing no. 8 on the key panel) so that key 12 becomes varies with the degree of touch or extent or coupling between the user-selected key. The invention is particularly useful a user's finger and a sensing element of a keyboard. Other where a user inadvertently touches keys 14 and 18, despite non-bistable touch sensors, such as an array of piezoelectric wishing to press the intended key 12. sensors in which the output from a given sensor increases Referring to FIG. 11, there is shown an array of closely with increasing activation force, share many of the properties 50 spaced capacitive keys in a key panel 50 which may form part of capacitive keys. Thus, much of the subsequent disclosure of a mobile phone handset. The keys of the key panel 50 should be understood as being relevant to non-capacitive keys represent numerals 1 to 9. Keys 1, 2 and 3 are located on an that also provide an output signal responsive to a degree of upper level designated A of the key panel 50; keys 4, 5 and 6 coupling between the key and a user's finger, stylus, or other are located on a middle level designated B; and keys 7, 8 and key-activating or pointing implement that is proximate the 55 9 are located on a lower level designated C of the key panel. key. A fingerprint represented by outline 52 (in dashed lines) Referring to FIG. 7, there is shown an array of 'N' tightly encompasses 7 different keys 1, 2, 4, 5, 6, 8, 9. The user's spaced capacitive keys in a key panel 10 which would benefit fingerprint 52 has a centroid location which is on key number from the invention. When using such small key panels it is 5. The amount of intersecting surface area between the inevitable that a finger will encompass much more than the 60 dashed line and each key area is a reasonable representation intended key. A finger touching a principle desired key elec- of the amount of signal level change each intersected key will trode 12 could easily create a 'fingerprint outline 20, as receive due to the touch. Often when a user's finger shown in dashed lines, where the fingerprint has a centroid approaches an intended key to be selected, the finger is at an location A. This fingerprint also encompasses key 14 other angle to the keys on the key panel. The finger outline 52 than the intended key. The amount of intersecting surface area 65 illustrates a touch on the key panel 50 which is at an angle to between the dashed line and each key area is a reasonable the keys as the finger (not shown) touches the key panel. The representation of the amount of signal level change each intended key to be selected by the user is key number 1 on 0 US 8,791,910 B2 17 18 10 upper level A. The tip of the finger touches key 1, however the The invention claimed is: fingerprint also encompasses keys 2, 4, 5, 6, 8 and 9. The 1. A method comprising, by one or more computing output signal from key 5 has the maximum signal strength. devices: The signals from keys 1, 2, 4 and 8 are above a threshold receiving two or more output signals responsive to two or value. Key 5 would initially be the favoured key as it has the 5 more capacitive couplings, each of the capacitive cou- highest signal strength, but in accordance with the invention plings occurring between a pointing object and one of keys 1 and 2 on the upper level A are selected by enhancing two or more sensing areas within a sensing region, each their signal strength and suppressing the signals from keys 4, of the sensing areas having a position within the sensing 5, 6, 8 and 9. The invention preferentially selects an upper key region; and based on its position in relation to other keys and based on the if two or more of the output signals each have an output- angle of touch by a person's finger. signal level that exceeds a predefined activation level, In this case, the output signal from each of keys 1 and 2 then selecting a particular one of the sensing areas with caused by capacitive coupling with a user's finger is above a output-signal levels exceeding the predefined activation threshold value and of substantially the same strength. An 16 level as an intended one of the sensing areas, the par- algorithm may be executed by a controller to ignore the ticular one of the sensing areas selected based on a signals from keys 1 and 2 until the user moves his finger away predefined ranking scheme that prioritizes the two or from key 2 to the intended key 1 so that the signal from key 2 more sensing areas based on the positions of the two or is reduced. more sensing areas within the sensing region. If a user touches two keys on the same level of the key 20 2. The method of claim 1, wherein each of the sensing areas panel, for example keys 7 and 8 on lower level C, then the DI has system disclosed in U.S. Ser. No. 11/279,402 (published as 3. The method of claim 2, wherein, according to the pre- US 2006-0192690 A1) may be used to select the desired key. defined ranking scheme, a sensing area with a higher pre- In an alternative embodiment, the output signal from the defined ranking is selected over a sensing area with a lower intended key 1 may not need to be enhanced to make it the 25 predefined ranking. user-selected key. An algorithm executed by a controller may 4. The method of claim 3, wherein, according to the pre- be able to process the signals from keys 1, 2, 4, 5, 6, 8 and 9 defined ranking scheme, among two or more sensing areas and make key 1 the user-selected key based on the vector of with a same predefined ranking, a sensing area that has a touch illustrated in FIG. 11. An algorithm can be arranged to higher output-signal level is selected over a sensing area that process different vectors of touch so as to determine the 30 has a lower output-signal level. user-selected key, in this case the key 1 on upper level A. 5. The method of claim 1, wherein: There are, of course, many possible variations and exten the predefined ranking scheme applies a weighting to the sions of the procedure. For example, one may consider a rare output-signal level of each of the sensing areas with case in which a user brings his or her finger up to a keyboard as output-signal levels exceeding the predefined activation so that the point of touch is exactly between two keys. In this level; and case, one could modify the depicted process to either select the particular one of the sensing areas selected based on the just one of those keys (e.g., by means of a known pseudo- predefined ranking scheme has a highest output-signal random number selection algorithm, or by sample sequence level, as weighted by the predefined ranking scheme, order) or by suppressing the output of both keys until the user 40 among the sensing areas with output-signal levels move his or her finger enough that one of the two keys had a exceeding the predefined activation level. higher output than the other. 6. The method of claim 1, wherein: Furthermore, although the above description has focussed the sensing areas are arranged in rows; on capacitive sensing technologies, embodiments of the each of the rows has a predefined ranking; and invention may be based on other coupling mechanisms, e.g. 45 according to the predefined ranking scheme, a sensing area magnetic coupling mechanisms. For example, the sensing in a row with a higher predefined ranking is selected over areas may be provided by magnetic field sensors and a point- a sensing area in a row with a lower predefined ranking. ing object may be magnetized do that the magnetic field 7. The method of claim 1, wherein: sensors are sensitive to its proximity. Other non-contact cou the sensing areas are arranged in columns; pling mechanisms could also be used 50 each of the columns has a predefined ranking; and Thus apparatus and methods are described for selecting according to the predefined ranking scheme, a sensing area which of a plurality of simultaneously activated keys in a in a column with a higher predefined ranking is selected keyboard based on capacitive sensors is a key intended for over a sensing area in a column with a lower predefined selection by a user. In embodiments of the invention keys are ranking. preferentially selected as the user intended key based on their 55 8. The method of claim 1, wherein: positions within the keyboard. Thus a key which is frequently the sensing areas are divided into two or more groups that wrongly activated when a user selects another key, e.g. each comprise two or more of the sensing areas; because the key is adjacent the intended key and the user iftwo or more of the sensing areas with output-signal levels normally passes his finger over it while approaching the exceeding the predefined activation level are in different desired key, can be suppressed relative to the desired key 60 groups, then according to the predefined ranking based on their relative positions. For example, keys may be scheme: associated with predefined rankings according to their posi- in each of the different groups, one of the sensing areas tion within the keyboard and in use keys are preferentially is selected as an intermediate one of the sensing areas select according to their rankings. Alternatively, signals from in a first stage of the predefined ranking scheme; and the keys may be scaled by weighting factors associated with 65 one of the intermediate ones of the sensing areas is their positions and a key selected according to the weighted selected as the intended one of the sensing areas in a signals. second stage of the predefined ranking scheme. 35 0 19 10 15 US 8,791,910 B2 20 9. The method of claim 1, wherein: 20. The media of claim 13, wherein: the sensing region comprises a keyboard and one or more the sensing areas are divided into two or more groups that of the sensing areas comprises a key of the keyboard; or each comprise two or more of the sensing areas; the sensing region comprises a keypad and one or more of iftwo or more of the sensing areas with output-signal levels the sensing areas comprises a key of the keypad. 5 exceeding the predefined activation level are in different 10. The method of claim 1, wherein the pointing object is a groups, then, according to the predefined raking ranking human finger or a stylus. scheme: 11. The method of claim 1, wherein, according to the in each of the different groups, one of the sensing areas predefined ranking scheme, an upper one of the sensing areas is selected as an intermediate one of the sensing areas is selected over a lower one of the sensing areas. in a first stage of the predefined ranking scheme; and 12. The method of claim 1, wherein the predefined ranking one of the intermediate ones of the sensing areas is scheme takes into account a vector of touch of the capacitive selected as the intended one of the sensing areas in a couplings between the pointing object and the sensing areas second stage of the predefined ranking scheme. within the sensing region. 21. The media of claim 13, wherein: 13. One or more computer-readable non-transitory storage the sensing region comprises a keyboard and one or more media embodying logic that is operable when executed to: of the sensing areas comprises a key of the keyboard; or receive two or more output signals responsive to two or the sensing region comprises a keypad and one or more of more capacitive couplings, each of the capacitive cou- the sensing areas comprises a key of the keypad. plings occurring between a pointing object and one of 20 22. The media of claim 13, wherein the pointing object is a two or more sensing areas within a sensing region, each human finger or a stylus. having a position within the sensing 23. The media of claim 13, wherein, according to the pre- region; and defined ranking scheme, an upper one of the sensing areas is if two or more of the output signals each have an output- selected over a lower one of the sensing areas. signal level that exceeds a predefined activation level, 25 24. The media of claim 13, wherein the predefined ranking then select a particular one of the sensing areas with scheme takes into account a vector of touch of the capacitive output-signal levels exceeding the predefined activation couplings between the pointing object and the sensing areas level as an intended one of the sensing areas, the par- within the sensing region. ticular one of the sensing areas selected based on a 25. An apparatus comprising: 30 a touch-sensitive user interface; and predefined ranking scheme that prioritizes the two or 5 one or more computer-readable non-transitory storage more sensing areas based on the positions of the two or media coupled to the touch-sensitive user interface that more sensing areas within the sensing region. embody logic operable when executed to: 14. The media of claim 13, wherein each of the sensing receive two or more output signals responsive to two or areas has a predefined ranking based on its position. 35 more capacitive couplings, each of the capacitive cou- 15. The media of claim 14, wherein, according to the pre- plings occurring between a pointing object and one of defined ranking scheme, a sensing area with a higher pre- two or more sensing areas within a sensing region of defined ranking is selected over a sensing area with a lower the touch-sensitive user interface, each of the sensing predefined ranking. areas having a position within the sensing region; and 16. The media of claim 15, wherein, according to the pre- 40 if two or more of the output signals each have an output- defined ranking scheme, among two or more sensing areas signal level that exceeds a predefined activation level, with a same predefined ranking, a sensing area that has a then select a particular one of the sensing areas with higher output-signal level is selected over a sensing area that output-signal levels exceeding the predefined activa- has a lower output-signal level. tion level as an intended one of the sensing areas, the 17. The media of claim 13, wherein: particular one of the sensing areas selected based on a the predefined ranking scheme applies a weighting to the predefined ranking scheme that prioritizes the two or output-signal level of each of the sensing areas with more sensing areas based on the positions of the two output-signal levels exceeding the predefined activation or more sensing areas within the sensing region. level; and 26. The apparatus of claim 25, wherein each of the sensing the particular one of the sensing areas selected based on the 50 areas has a predefined ranking based on its position. predefined ranking scheme has a highest output-signal 27. The apparatus of claim 26, wherein, according to the level, as weighted by the predefined ranking scheme, predefined ranking scheme, a sensing area with a higher among the sensing areas with output-signal levels predefined ranking is selected over a sensing area with a lower exceeding the predefined activation level. predefined ranking. 18. The media of claim 13, wherein: 55 28. The apparatus of claim 27, wherein, according to the the sensing areas are arranged in rows; predefined ranking scheme, among two or more sensing areas each of the rows has a predefined ranking; and with a same predefined ranking, a sensing area that has a according to the predefined ranking scheme, a sensing area higher output-signal level is selected over a sensing area that in a row with a higher predefined ranking is selected over has a lower output-signal level. a sensing area in a row with a lower predefined ranking. 60 29. The apparatus of claim 25, wherein: 19. The media of claim 13, wherein: the predefined ranking scheme applies a weighting to the the sensing areas are arranged in columns; output-signal level of each of the sensing areas with each of the columns has a predefined ranking; and output-signal levels exceeding the predefined activation according to the predefined ranking scheme, a sensing area level; and in a column with a higher predefined ranking is selected 65 the particular one of the sensing areas selected based on the over a sensing area in a column with a lower predefined predefined ranking scheme has a highest output-signal ranking level, as weighted by the predefined ranking scheme, 45 0 US 8,791,910 B2 22 10 21 among the sensing areas with output-signal levels exceeding the predefined activation level. 30. The apparatus of claim 25, wherein: the sensing areas are arranged in rows; each of the rows has a predefined ranking; and according to the predefined ranking scheme, a sensing area in a row with a higher predefined ranking is selected over a sensing area in a row with a lower predefined ranking. 31. The apparatus of claim 25, wherein: the sensing areas are arranged in columns; each of the columns has a predefined ranking; and according to the predefined ranking scheme, a sensing area in a column with a higher predefined ranking is selected over a sensing area in a column with a lower predefined ranking 32. The apparatus of claim 25, wherein: the sensing areas are divided into two or more groups that each comprise two or more of the sensing areas; iftwo or more of the sensing areas with output-signal levels 20 exceeding the predefined activation level are in different groups, then, according to the predefined ranking scheme: in each of the different groups, one of the sensing areas is selected as an intermediate one of the sensing areas in a first stage of the predefined ranking scheme; and one of the intermediate ones of the sensing areas is selected as the intended one of the sensing areas in a second stage of the predefined ranking scheme. 33. The apparatus of claim 25, wherein: the sensing region comprises a keyboard and one or more of the sensing areas comprises a key of the keyboard; or the sensing region comprises a keypad and one or more of the sensing areas comprises a key of the keypad. 34. The apparatus of claim 25, wherein the pointing object is a human finger or a stylus 35. The apparatus of claim 25, wherein, according to the predefined ranking scheme, an upper one of the sensing areas is selected over a lower one of the sensing areas. 36. The apparatus of claim 25, wherein the predefined ranking scheme takes into account a vector of touch of the capacitive couplings between the pointing object and the sensing areas within the sensing region. 37. The apparatus of claim 25, wherein the touch-sensitive user interface is a touchscreen or touchpad. * * * * * 0 UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. APPLICATION NO. Page 1 of 1: 8,791,910 B2: 13/043231: July 29, 2014: Harald Philipp DATED INVENTOR(S) It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below: In the Claims Col. 20, Ln. 6: After "predefined" and before "ranking" delete "raking". Signed and Sealed this Seventeenth Day of March, 2015 Michelle K. Lee Michelle K. 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No. 11/750,430, Notice of Allowance from USPTO, Oct. 29, 2010. * cited by examiner 0 U.S. Patent Jul. 29, 2014 Sheet 1 of 5 US 8,791,910 B2 in 110 104 104 to 102 S 100 108 Fig. 1 0 U.S. Patent Jul. 29, 2014 Sheet 2 of 5 US 8,791,910 B2 D23) 11 21 31 42 52 62 (789 73 83 93 *4 Il 04 #4 Fig. 2 Fig. 3 (1122) 30) 43 54 Fig. 4 Fig. 5 0 U.S. Patent Jul. 29, 2014 Sheet 3 of 5 US 8,791,910 B2 Hoedsel DIENOS pe no 0 0 moo # TODOS Fig. 6 0 U.S. Patent Jul. 29, 2014 Sheet 4 of 5 US 8,791,910 B2 UP Fig. 7 らー ロロロロロロロー ロロロロロロロ 口ロロロロロロロ ロロロロロロロロ L Fig. 8 SIGNAL CHANGE SIGNAL ZONVHS THRESHOLD--- うーーーーーーーー ----- THRESHOLD -- 18 18 KEY# 12 14 16 Fig. 9a KEY# 12 14 16 Fig. 9b 0 U.S. Patent Jul. 29, 2014 Sheet 5 of 5 US 8,791,910 B2 opo 121 1 2 3 | .5-6 GiB (9 7 Fig. 10 50 UP ^ [19 21.3 c7] 8.1,9) 52 Fig. 11 0 US 8,791,910 B2 CAPACITIVE KEYBOARD WITH of the capacitive response to a body other than the pointing POSITION-DEPENDENT REDUCED KEYING body, e.g., sensing the user's hand in addition to sensing his or AMBIGUITY her pointing finger. U.S. Pat. No. 5,730,165 teaches a capacitive field sensor RELATED APPLICATION 5 employing a single coupling plate and a method of detecting a change in capacitance of the coupling plate, Cx, to ground. This application is a continuation, under 35 U.S.C. $120, of The apparatus taught in U.S. Pat. No. 5,730,165 comprises U.S. patent application Ser. No. 11/750.430, filed 18 May pulse circuitry for charging the coupling plate and for subse- 2007, which claims the benefit, under 35 U.S.C. $119(e), of quently transferring the charge from the plate into a charge U.S. Provisional Patent Application No. 60/803,138, filed 25" od 25 10 detector, which may be a sampling capacitor, Cs. The trans- May 2006. ferring operation is carried out by means of a transfer switch electrically connected between the coupling plate and the TECHNICAL FIELD charge detector. The disclosure of U.S. Pat. No. 5,730,165 is herein incorporated by reference. 15 U.S. Pat. No. 6,466,036 teaches pulse circuitry for measur- This disclosure relates generally to capacitive keyboards. ing capacitance to ground, the circuitry comprising a plurality BACKGROUND OF THE INVENTION of electrical switching elements, each of which has one side electrically connected to either a power supply voltage or to a circuit ground point. This circuit arrangement, which may be The invention relates to touch sensitive user interfaces 20 used with a keyboard as well as for many other applications, having an array of sensing elements and methods for deter- is more compatible with available integrated circuit design mining which of a plurality of sensing elements in simulta- and manufacturing practices than is prior art pulse circuitry, neous detection is intended by a user for selection. Thus the which commonly had one side of at least one switching ele- invention relates to a method and apparatus for controlling ment floating. These improved arrangements thereby provide touch sensitive user interfaces, e.g. to assist in preventing 25 superior performance at a lower manufacturing cost. The accidental false inputs from keys adjacent to a selected key in disclosure of U.S. Pat. No. 6.466.036 is herein incorporated a capacitive keyboard. by reference. The use of capacitive proximity sensors, for example as Attempts made to address the above-described problem of keys in a keypad, is becoming more common. Capacitive keying ambiguity with capacitive sensors are described in sensors are frequently preferred to mechanical switches for a 30 U.S. Pat. No. 6,993,607 and U.S. patent Ser. No. 11/402,269 number of reasons. For example, capacitive sensors require (published as US 2006/0192690 A1). The disclosures of U.S. no moving parts and so are less prone to wear than their Pat. No. 6,993,607 and U.S. Ser. No. 11/279,402 are herein mechanical counterparts. Capacitive sensors can also be incorporated by reference. made in relatively small sizes so that correspondingly small, U.S. Pat. No. 6,993,607 describes a method and apparatus and tightly packed keypad arrays can be provided. Further- vided Further 35 for reducing keying ambiguity on a keyboard having an array more, capacitive sensors can be provided beneath an environ- of proximity sensors. The ambiguity is reduced by an iterative mentally sealed outer surface. This makes their use in wet technique of repeatedly measuring a detected signal strength environments, or where there is a danger of dirt or fluids associated with each key in the array having respective output signals responsive to a degree of coupling between the key entering a device being controlled attractive. Furthermore 40 and a user, comparing all of the measured signal strengths to still, manufacturers often prefer to employ interfaces based find a maximum, determining that the key having the maxi- on capacitive sensors in their products because such inter- mum signal strength is the unique user-selected key, and faces are often considered by users to be more aesthetically maintaining the user selected key until the signal from that pleasing than conventional mechanical input mechanisms key falls below a threshold value. The signals from all the (e.g. push-buttons). 45 other keys are suppressed or ignored during the maintaining However, a drawback of interfaces based on arrays of step. capacitive sensors is that an object to be sensed, e.g. a user's U.S. Ser. No. 11/402,269 (published as US 2006-0192690 pointing finger, will often be capacitively coupled to multiple A1) describes an iterative method and apparatus for removing capacitive sensors at the same time. This means that multiple keying ambiguity on a keyboard by measuring a detected capacitive sensors can appear to be activated simultaneously 50 signal strength associated with each key in an array, compar- which can lead to an ambiguity as to which capacitive sensor ing the measured signal strengths to find a maximum, deter- in the array is intended for selection. This problem can be mining that the key having the maximum signal strength is the particularly apparent for sensors arranged into a closely unique user-selected first key, and maintaining that selection packed array, e.g. in a keypad for a cellular telephone. With a until either the first key's signal strength drops below some small keypad such a this, a user's finger is likely to overlap 55 threshold level or a second key's signal strength exceeds the multiple keys at the same time, i.e. both an intended key for first key's signal strength. When any key is selected its signal selection, and also keys adjacent to it. This can be especially strength value may be enhanced relative to all the other keys problematic if the user has large fingers, or if he presses on a so as to deselect all other keys. panel over the sensors with enough force to deform his or her finger and so increase the effective area of his finger tip. The 60 SUMMARY OF THE INVENTION same sort of effect is found when a conducting film is spilled on a keyboard, in which case the user's finger is sensed as According to a first aspect of the invention there is provided though it were the size of the puddle. Problems of this sort are a touch-sensitive user interface, comprising: a plurality of particularly acute in cash register keyboards used in food sensing areas arranged within a sensing region, each sensing tablishments where beverage and food sauce spills 65 area having a position within the sensing region; a measure- are a frequent occurrence. Another problem with capacitive ment circuit coupled to the sensing areas and operable to keypads, known as the "handshadow" effect, arises because generate output signals responsive to a coupling between a 0 US 8,791,910 B2 pointing object and respective ones of the sensing areas; and predefined parts of the sensing region over sensing areas a controller operable to receive the output signals from the having positions farther from the predefined parts of the sens- measurement circuit and to determine a selected one of the ing region. For example, the predefined parts of the sensing sensing areas by taking account of both the output signals region may be parts that are furthest from the user along a associated with the sensing areas and the positions of the 5 direction in which a pointing object approaches the screen. sensing areas within the sensing region. This in effect suppresses the sensing areas in parts of the The user interface may further be operable to output an sensing region that the pointing object passes over when a output signal indicative of the selected one of the sensing user wished to select a sensing area in one of the predefined areas. parts of the sensing region (e.g. a top row, or a top corner) of The user interface may be based on capacitive effects, i.e. 10 the sensing region. such that the coupling between a pointing object and respec The user interface may be such that in normal use a point- tive ones of the sensing areas is a capacitive coupling. The ing object approaches the sensing region from a normal user interface may alternatively be based on other coupling approach direction (which will likely also correspond with a mechanisms, for example magnetic coupling. direction of extent of the pointing object), and sensing areas By taking account of the positions of sensing areas within 15 are preferentially selected according to their positions along the sensing region as well as their associated output signals, the normal approach direction. Furthermore, the user inter- the controller is able to more reliably determine which one of face may be such that in normal use the pointing object a plurality of sensing areas (keys) in a sensing region (keypad approaches the sensing region from one of a plurality of keyboard) in simultaneous detection is intended by a user for normal approach directions, and sensing areas are preferen- selection. This is because the controller may be configured to 20 tially selected according to their positions along the more take account of which keys in a keypad are more likely to be than one normal approach directions. Thus the controller can wrongly selected as being intended by a user by virtue of their be operable to determine a user-selected key taking particular positions, in particular with respect to the orientation of the account of how the user interface is normally oriented with pointing object. For example, in a keypad in which a pointing respect to a user. object normally passes over a given key or keys when a user 25 The sensing areas may be arranged in rows and columns, selects a desired key, the controller can in effect suppress and the controller may take account of the positions of the signals from the non-user selected keys over which the point- sensing areas when determining a selected sensing area by ing object passes based on their positions. preferentially selecting sensing areas in one row over sensing For example, each sensing area may be associated with a areas in another row. Furthermore, or alternatively, sensing predefined priority ranking according to its position within 30 areas in one column may be preferentially selected over sens- the sensing region, and the controller may be operable to ing areas in another column. preferentially select sensing areas according to their ranking. The touch-sensitive user interface may further comprise a Thus for a keypad comprising keys arranged in rows and further plurality of sensing areas arranged within a further columns, keys in a top row (relative to the orientation of a sensing region, each further sensing area having a position pointing object) may be assigned a higher rank than keys in a 35 within the further sensing region, wherein the measurement lower row, and hence be preferentially selected over them. circuit is coupled to the further sensing areas and operable to The ranking scheme may be applied such that the highest generate further output signals responsive to a coupling (e.g. ranked key in a plurality of keys deemed to be in simultaneous a capacitive or magnetic coupling) between the pointing activation based on their output signals, is taken to be the user object and respective ones of the further sensing areas; and selected key. In the event that multiple activated keys have the 40 wherein the controller is further operable to receive the fur- same ranking, and this ranking is the highest ranking of all ther output signals from the measurement circuit and to deter- activated keys, conventional techniques may be used to deter mine a selected one of the further sensing areas by taking mine which key to select. For example, for the keys having the account of both the further output signals associated with the same (and highest) priority, the key having the biggest output further sensing areas and the positions of the further sensing signal, the key being first to be activated, or a random one of 45 areas within the further sensing region. the keys, may be selected. Alternatively, a null response may Where the touch-sensitive user interface comprises such a be reported (i.e. no key selected), thus forcing the user to further plurality of sensing areas, the controller may be fur- re-adjust their pointing. ther operable to determine a selected one of the selected one Alternatively, the ranking scheme may be such that the of the first-mentioned sensing areas and the selected one of controller is arranged to determine the selected one of the 50 the further sensing areas based on the output signals associ- sensing areas by applying a weighting to the output signals ated with these selected sensing areas. according to the positions of the corresponding sensing areas According to a second aspect of the invention there is in the sensing region. The weighting may be applied by scal- provided an apparatus/device comprising a touch-sensitive ing the output signals by a scale factor associated with the user interface according to the first aspect of the invention. corresponding sensing areas so that sensing areas associated 55 The apparatus/device, may, for example, be a cellular tele- with higher scale factors are preferentially selected over sens- phone, an oven, a grill, a washing machine, a tumble-dryer, a ing areas having lower scale factors. This has the advantage of dish-washer, a microwave oven, a food blender, a bread allowing an activated key having a lower ranking than another maker, a drinks machine, a computer, an item of home audio- activated key to still be selected if its output signal is suffi- visual equipment, a portable media player, a PDA, and so on. ciently high, that is to say, a sufficiently high output signal can 60 According to a third aspect of the invention there is pro- overcome a lower ranking. This can help, for example, if there vided a method for determining which one of a plurality of is a concern that complete "block out" of the lowest ranked sensing areas in a sensing region of a touch-sensitive user key(s) might otherwise occur. interface is selected by a pointing object, the method com- The controller may be operable to take account of the prising: measuring a coupling (e.g. a capacitive coupling or a positions of the sensing areas within the sensing region when 65 magnetic coupling) between the pointing object and respec- determining the selected one of the sensing areas by prefer- tive ones of the sensing areas and generating output signals entially selecting sensing areas having positions nearer to responsive thereto; and determining one of the sensing areas