Neodron LTD v. Hewlett Packard Enterprise Company

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

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5 Exhibit 5 Case 6:19-cv-00319-ADA Document US009024790B2 (12) United States Patent Philipp (10) Patent No.: (45) Date of Patent: US 9,024,790 B2 *May 5, 2015 (54) CAPACITIVE KEYBOARD WITH NON-LOCKING REDUCED KEYING AMBIGUITY USPC ............ 341/20, 22, 26, 33; 345/173; 715/773 See application file for complete search history. (56) References Cited (75) Inventor: Harald Philipp, Zug (CH) U.S. PATENT DOCUMENTS (73) Assignee: Atmel Corporation, San Jose, CA (US) 4,616,213 A 4,651,133 A (*) Notice: 10/1986 Danish 3/1987 Ganesan et al. (Continued) Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 444 days. This patent is subject to a terminal dis- claimer. FOREIGN PATENT DOCUMENTS EP WO 1 381 160 A11/2004 WO 2012/129247 A2 9/2012 ........... HO3M 11/20 OTHER PUBLICATIONS (21) Appl. No.: 13/347,312 (22) Filed: Jan. 10, 2012 (65) Prior Publication Data US 2012/0105260 A1 May 3, 2012 Intellectual Property Office (IPO), Taiwan Office Action and English Translation of Text and Search Report, ROC (Taiwan) Patent Appl. No. 095123644, file 080900.0489 (14 pgs), Jan. 23, 2013. (Continued) Related U.S. Application Data 53) Continuation of application No. 12/899,229, filed on Oct. 6, 2010, now Pat. No. 8,102,286, which is a continuation of application No. 11/279,402, filed on Apr. 12, 2006, now Pat. No. 7,821,425, which is a Primary Examiner — Albert Wong (74) Attorney, Agent, or Firm — Baker Botts LLP (57) ABSTRACT (Continued) (51) Int. CI. HO3M 11/00 (2006.01) GO6F 3/023 (2006.01) G06F 3/041 (2006.01) (Continued) (52) U.S. CI. CPC ........... G06F 370237 (2013.01); G06F 3/0416 (2013.01); G06F 3/044 (2013.01); HO3K 17/9622 (2013.01); HO3K 17/9643 (2013.01); HO3K 2217/960705 (2013.01) (58) Field of Classification Search CPC .... HO3M 11/20; G06F 3/0237; G06F 3/0416; G06F 3/044 Keyboards, keypads and other data entry devices can suffer from a keying ambiguity problem. In a small keyboard, for example, a user's finger is likely to overlap from a desired key to onto adjacent ones. An iterative method of removing key- ing ambiguity from a keyboard comprising an array of capaci- tive keys involves measuring a signal strength associated with each key in the array, comparing the measured signal strengths to find a maximum, determining that the key having the maximum signal strength is the unique user-selected key, and maintaining that selection until either the initially selected key's signal strength drops below some threshold level or a second key's signal strength exceeds the first key's signal strength. 24 Claims, 7 Drawing Sheets Signal Strength Threshold Key # 1 2 5 US 9,024,790 B2 CAPACITIVE KEYBOARD WITH NON-LOCKING REDUCED KEYING AMBIGUITY than is prior art pulse circuitry, which commonly had one side of at least one switching element floating. These improved arrangements thereby provide superior performance at a lower manufacturing cost. The disclosure of U.S. Pat. No. 5 6,466,036 is herein incorporated by reference. RELATED APPLICATIONS COM This application is a continuation of U.S. application Ser. SUMMARY OF THE INVENTION No. 12/899,229 filed Oct. 6, 2010, which is a continuation of U.S. application Ser. No. 11/279,402 filed Apr. 12, 2006, now One aspect of the invention is that it may provide an itera- U.S. Pat. No. 7,821,425, which claims priority from U.S. 10 tive method of removing keying ambiguity by measuring a Provisional Application No. 60/597,851 filed Dec. 21, 2005, detected signal strength associated with each key in an array, and is a continuation-in-part of U.S. application Ser. No. comparing the measured signal strengths to find a maximum, 11/160.885 filed Jul. 14. 2005. now U.S. Pat. No. 7.256.714. determining that the key having the maximum signal strength which is a continuation of U.S. application Ser. No. 10/617, is the unique user-selected first key, and maintaining that 602 filed Jul. 11, 2003, now U.S. Pat. No. 6,993,607, which 15 selection until either the first key's signal strength drops claims priority from U.S. Provisional Application No. below some threshold level or a second key's signal strength 60/395,368, filed Jul. 12, 2002. exceeds the first key's signal strength. When any key is selected its signal strength value may enhanced relative to all BACKGROUND INFORMATION the other keys so as to deselect all other keys. In this aspect, 20 the array under consideration may be a keyboard, or any The invention relates to method and apparatus for control convenient subset thereof. ling an array of non-bistable keys, such as capacitive position A particular preferred embodiment of the invention is an sensors, and, more specifically for preventing accidental false array of capacitive keys in which each key has a respective inputs from keys adjacent to a selected key in a capacitive detection integrator counter (DI) associated with it. Each DI keyboard. 25 is a clocked counter that counts up by one incremental value Arrays of capacitive proximity sensors are often used in on each capacitive acquisition cycle during which a signal keyboards, keypads and other touch-input apparatus. Two strength from the associated key is above some nominal characteristics of capacitive sensors that lead to their use threshold value, and that counts down toward zero if the instead of conventional metallic switches are: 1) Capacitive signal strength is less than the nominal value. A controller sensors can be made in small sizes, which is desirable if a 30 receives a respective input from each DI and determines that small, tightly packed keyboard is required; and 2) Capacitive one of the keys is selected, e.g., wins, when the detection sensors are particularly easy to environmentally seal, which is integration (DI) count associated with that key meets a desirable if the keyboard is to be used in a wet environment or respectively selected terminal count value, TC. The incre- where there is a concern that contaminants may be spilled on mental magnitude used for counting down can be the same as the keyboard. 35 that for counting up, e.g., 1, or it can be different, e.g., 2, to Conventional capacitive sensors, when tightly packed, or preferentially accelerate the count-down 'losing process when used in the presence of conductive liquid films, suffer a over the winning process, in order to facilitate better suppres- keying ambiguity problem. In a small keyboard, for example, sion of noise. The rate of counting down any of the DI a user's finger is likely to overlap from a desired key to onto counters can also be the complete value, i.e., the DI can be adjacent ones. This is especially problematic if the user has 40 cleared in one cycle. In this embodiment, when two or more large fingers or if he or she presses on the keyboard surface keys have signal strengths above their nominal thresholds, the hard enough to deform his or her finger. The same sort of key with the lesser signal strength will have its associated DI effect is found when a conducting film is spilled on a key- decremented or cleared each cycle while this condition exists. board, in which case the user's finger is sensed as though it If any two or more keys have equal and maximal signal were the size of the puddle. Problems of this sort are particu- 45 strengths, such keys' DI's will continue to increment until the larly acute in cash register keyboards used in food service first to reach its TC 'wins' and is set as the unique user- establishments where beverage and food sauce spills are a selected key. frequent occurrence. In another aspect of the invention, the DI of a key selected In his U.S. Pat. No. 5,730,165, the inventor teaches a at a first instant may be decremented or cleared and that key capacitive field sensor employing a single coupling plate and 50 deselected even if the signal strength of that key is above the od of detecting a change in capacitance of the coupling threshold value and its DI equals its associated TC value, if plate, Cx, to ground. The apparatus taught in U.S. Pat. No. second key becomes selected at a later instant by virtue of its 5,730,165 comprises pulse circuitry for charging the coupling signal strength being greater than the signal strength of the plate and for subsequently transferring the charge from the first key while also being above its own threshold value and plate into a charge detector, which may be a sampling capaci- 55 having its associated DI equal its associated TC. If there are tor, Cs. The transferring operation is carried out by means of multiple keys with signal strengths above their associated a transfer switch electrically connected between the coupling threshold values, their associated Dis will count up and down plate and the charge detector. The disclosure of U.S. Pat. No. in competition, until one key's DI finally equals its TC and 5,730,165 is herein incorporated by reference. wins over all others including over the previously selected In his U.S. Pat. No. 6,466,036 the inventor teaches pulse 60 key. circuitry for measuring capacitance to ground, the circuitry In the above discussions, it should be understood that the comprising a plurality of electrical switching elements, each principle of having one signal greater than another has been of which has one side electrically connected to either a power somewhat simplified for explanatory purposes. In order to supply voltage or to a circuit ground point. This circuit avoid indecisiveness and eliminate oscillation between two or ch may be used with a keyboard as well as 65 more keys having more or less the same signal strengths, the for many other applications, is more compatible with avail winning key may preferably be given a slight advantage in able integrated circuit design and manufacturing practices subsequent repetitions of the decision process. This may be vail- 5 US 9,024,790 B2 done, for example, by requiring a non-selected key's signal to form. Moreover, it may be noted that different embodiments exceed the currently selected key's signal by a small amount. of the invention may provide various combinations of the This can be done by subtracting a small amount off the signals recited features and advantages of the invention, and that less of non-selected keys, or by adding a small amount onto the than all of the recited features and advantages may be pro- selected key's signal. 5 vided by some embodiments. An advantage of this method over those disclosed in my U.S. Pat. No. 6,993,607 is that the method disclosed herein DESCRIPTION OF THE DRAWING permits the smooth rollover of key selection as a finger slides from one key to the next, while still reducing key ambiguity. FIGS. la to lc show an array of tightly spaced capacitive In the aforementioned patent, the first key to win remains 10 buttons selected even if the maximal signal strength has shifted to a FIG. 2 shows a 2-D touch surface such as a capacitive new key, provided that the first key has enough signal strength mouse surface or a capacitive touch screen, with buttons left to retain its state, i.e., by having its signal strength in around it. excess of its associated threshold value. Therefore the instant FIG. 3 shows a 2-D touch surface such as a capacitive invention may be referred to as 'non-locking'key ambiguity 15 mouse surface or a capacitive touch screen, with a guard ring reduction. disposed around it to suppress activation of the touch screen In yet another aspect of the invention, if the signal strengths dispose of two keys that are approaching a detection threshold value area when a finger strays just outside the 2-D mouse or screen and that are both in a defined keyboard neighborhood both area. exceed the threshold value and their signal strengths are equal 20 FIG. 4 is a schematic block diagram of a preferred appa- to each other (or are within a selected tolerance value) at the ratus of the invention. same time, an algorithm executed by a controller may be used FIG. 5a is a flow chart showing logical operations carried to declare one of the two keys to be active and the other to be out in a preferred method of the invention when Key 1 is inactive. It will be recognized that a wide variety of algo initially active. rithms are possible and include, but are not limited to, a 25 FIG. 5b is a flow chart showing logical operations carried random, or pseudo-random selection of the active key, or a out in a preferred method of the invention when Key 1 is declaration of activity based on which key was scanned first. initially inactive. The principle also applies in the minimal case where the DI's terminal count (TC) is chosen to be equal to one. This is DETAILED DESCRIPTION functionally the same as though there were no DI, but rather 30 just a simple signal comparison function with an inhibiting In studying this Detailed Description, the reader may be logic gate following it. Here, the inputs to the inhibiting gate aided by noting definitions of certain words and phrases used also includes the logical comparisons of the signal strengths throughout this patent document. Wherever those definitions among the keys in a neighborhood in order to skew subse are provided, those of ordinary skill in the art should under- quent comparisons to favor the already selected key over 35 stand that in many, if not most instances, such definitions competing keys having respective output signals above apply to both preceding and following uses of such defined respective threshold values. words and phrases. At the outset of this Description, one may Those skilled in the keyboard arts will understand that the note that the terms "include" and "comprise," as well as above-mentioned neighborhoods can be defined in a wide derivatives thereof, mean inclusion without limitation; the variety of ways. In some cases, a neighborhood of a given key 40 may consist of all the keys immediately adjacent the given term "or," is inclusive, meaning and/or. The word 'key' as key, or may comprise all the keys having no more than one key generally used in this Disclosure and as specifically used in between them and the given kev. In other cases, the neighbor- the Claims attached hereto refers to a touchable portion of a hood may comprise all the keys in a matrix array-e.g., in a mechanical to electrical transducing device that is non- keyboard for use in a numerical data entry application in 45 bistable in nature. This term specifically excludes conven- which only one key is to be active at a time so that the tional mechanical switches in which two or more electrical sequence of input digits is uniquely determined. In other conductors are moved into or away from contact with each cases, such as in a typing or computer-input keyboard, the other to make or break an electrical connection. The terms neighborhood of a key may comprise all other keys in the keyboard', 'key pad'and the like all refer to arrays of keys for keyboard except for special purpose keys, such as a capitali- 50 data input without limitation as to the size or configuration of zation shift key, a control key, and the like. Moreover, some the array. A 'key' can also be a dimensional sensing surface embodiments of the invention provide a keyboard that is such as an XY touch screen or a "trackpad, or a sensing zone configurable by a user who programs a controller to selec not intended for normal human data entry such as an object or tively consider or ignore various keys in an array. In some body part sensor. 'Touch'can mean either human or mechani- cases there might be two neighborhoods, each acting inde- 55 cal contact or proximity to a key. 'User' can mean either a pendently of the other for key ambiguity resolution purposes. human or a mechanical object. A 'finger' can be, inter alia, a Although it is believed that the foregoing rather broad human finger, a mechanical finger or a stylus. summary description may be of use to one who is skilled in Capacitive sensors, unlike bistable electromechanical the art and who wishes to learn how to practice the invention, switches which are either open or closed, provide a signal that it will be recognized that the foregoing recital is not intended 60 varies with the degree of touch or extent or coupling between to list all of the features and advantages. Those skilled in the a user's finger and a sensing element of a keyboard. Other art will appreciate that they may readily use both the under non-bistable touch sensors, such as an array of piezoelectric lying ideas and the specific embodiments disclosed in the sensors in which the output from a given sensor increases following Detailed Description as a basis for designing other with increasing activation force, share many of the properties arrangements for carrying out the same purposes of the 65 of capacitive keys. Thus, much of the subse present invention and that such equivalent constructions are should be understood as being relevant to non-capacitive keys within the spirit and scope of the invention in its broadest that also provide an output signal responsive to a degree of 5 US 9,024,790 B2 coupling between the key and a user's finger, stylus, or other drawing depicts a two-dimensional touch surface, the same key-activating or pointing implement that is proximate the considerations apply to a one-dimensional touch surface of key. the sort commonly referred to as a slider, scroll-wheel, or the Turning now to FIG. 1A, one finds an array of 'N' tightly like. spaced capacitive keys in a key panel 11 which would benefit 5 FIG. 3. shows a configuration of a capacitive touch input from the invention. When using such small key panels it is area 6 with a surrounding 'key'8. The principles of operation inevitable that a finger will encompass much more than the described in conjunction with FIG. 1 apply similarly to FIG. intended key. A finger touching a principle desired key elec- 3, in that the area 6 can be treated as a single key with a single trode 1 could easily create a 'fingerprint' outline 3, as shown signal strength for purposes of key suppression, while the in dashed lines, where the fingerprint has a centroid location 10 outer 'key'8 acts to detect errant touch which falls partially on A. This fingerprint also encompasses keys other than the both 6 and 8. The area 6 can comprise any suitable input intended key. The amount of intersecting surface area arrangement such as a capacitive mouse surface, a capacitive between the dashed line and each key area is a reasonable touch screen or a keypad comprising discrete keys. representation of the amount of signal level change each In this example, the guard electrode 8 is not necessarily intersected key will receive due to the touch, although even 15 intended as an actual control key. A finger sliding from 3 to 4 non-touched keys will also see an increase in signal due to would still potentially leave the active screen 6, but in fact the mere finger proximity and to fringe-field effects within the touch would not be legal since its areal centroid at 'B' lies touch panel. principally outside the input area. "Key'8 detects this out-of- se, the desire is to select the one and only one key position fingerprint and appropriate logic causes the screen 6 which is intended by the user while suppressing outputs from 20 to fall out of detection or to be ignored by further processing. adjacent keys intersected by the fingerprint. In this 'non- It may be noted that some uses of the guard ring structure do locking' key suppression invention, if the finger slides to a not involve having a finger touching the keypad. For example, new key location 4, shown dotted with its centroid at location one could arrange a guard ring around a capacitive cell phone B, where the movement is shown by the arrow from A to B, keypad and use the guard ring output to suppress readings this movement will not cause the first key 1 to remain solely 25 from all the keys in the keypad while the user was talking on active even though it has sufficient signal to still retain its the cell phone and holding the keypad of the phone against his state, i.e., its signal still lies above its threshold level despite or her head. being reduced by the movement to a new key. Instead, the The guard electrode 'key' 8 in the latter case can also be a invention provides that the newly intended key 2, having a discrete solid electrode shape, for example a rectangle, disk, larger signal level due to a higher degree of fingerprint inter- 30 arc, or stripe or other shape, placed in some other location section than key 1, becomes the solely active key by switching reasonably proximate input area 6. This guard electrode off the active state of key 1. would be activated by placing the product against the user's FIGS. 16 and 1c further detail the change in signals on the head or other body part (for example placing the product in a keys of FIG. 1a by virtue of the relative electrode surface clothing pocket with the keypad side towards the user's body) intersections with the fingerprint first at location A (FIG. 1b) 35 in order to suppress further output from the keypad under and then at location B (FIG. 1c). The signal strengths are such adverse conditions. A suitable position for such a 'key' shown in the bar plots in the lower portions of the respective might be near the earpiece of a cell phone, some distance figures. It is desired that in order for a key to 'win' the status away from the keypad or touchscreen. of user-selected key, its signal change must exceed a thresh The guard electrode "key' 8 can also be either a ring as old value, and its signal has to be the largest. In FIG. 1b, key 40 shown in FIG. 3, or a discrete solid electrode shape, such as a 1 wins. In FIG. 1c, key 2 wins. rectangle, disk, arc, or stripe or other shape, placed in some If the key selection method operates solely by picking a other location reasonably proximate the input area 6 so as to maximum signal strength, the keyboard may be subject to an be activated by a mechanical closure. This could provide a undesirable rapid switching back and forth between two keys cover which, when closed, would cause the guard key 8 to having nearly-identical signal strengths (e.g., fingerprint 45 induce the suppression of input area 6. areas). This sort of chatter'is preferably prevented by biasing In order to make the determination of an out-of-position or skewing the key selection method to favor an already fingerprint for use with the apparatus shown in FIG. 3, the selected key. That is, the switchover process is made slightly same sorts of biasing arrangemer more difficult than would occur with straight equivalence. chatter as discussed supra. However, relationships described This bias may be provided in many ways in subsequent key 50 above with respect to FIG. 2 presume the gain of the sensing selection decisions. These ways may be equivalent to adding channels with respect to finger surface area to be comparable, an incremental value to the signal associated with the selected so that equivalent fingerprint surface areas on different keys key; multiplying the signal strength of the selected key by a produce comparable signal changes. This is not always the value greater than one in subsequent selections; subtracting a case in any of the instances described with respect to FIGS. respective incremental value from the signal strengths asso- 55 la-c, 2 or 3. The electrode sizes of different keys may not be ciated with each of the non-selected keys; or multiplying the equal, and for various reasons (such as stray loading capaci- signal strength of each of the non-selected keys by a respec tance variations, etc.) the electrical gains among the various tive value less than one. keys can differ. In these instances the incremental values FIG. 2 shows a configuration of a capacitive mouse or added might be negative. Alternatively, signals from compet- capacitive touch screen area 6 with surrounding buttons 7. 60 ing keys could be scaled into a state of equivalence by using The principles of operation described in conjunction with scaling constants that are experimentally determined to FIG. 1a-c apply similarly to FIG. 2, in that the area 6 can be accord with a particular configuration. In any event, one can treated as a single key with a single signal strength for pur scale and/or offset the signals into equivalence for compari- poses of key suppression. FIG. 2 applies when the keys 7 are son purposes and thereby create the desired suppression very close to pointing surface 6 and fingerprints 3 and 4 can 65 effect without chatter. overlap both the capacitive screen and one or more capacitive Turning now to FIG. 4, one finds a schematic representa- buttons. Moreover, it should be recognized that although the tion of apparatus of the invention 10, comprising an array of "8d 5 US 9,024,790 B2 1 Hers. ren N capacitive proximity sensors 12 labeled "Key 1", ..., "Key to become inactive and resets their respective DI counters. In N". Each of the sensors 12 has an output to a respective keyboards comprising a large number of keys, only one of counter logic 14 that supplies data to and is controlled by which should be active at a time, this OFF status will, of suitable control logic 16. Those skilled in the electronic arts course, be the predominant result of an analysis of the output will appreciate that although the counters 14 and control logic 5 of any given key. The action of incrementing or decrementing 16 are depicted with discrete blocks in the schematic diagram, of counter values as described supra can be numerically these features could be provided either by separate physical reversed to achieve the same effect and should be considered circuit elements, or could all be provided by a single micro to be logically equivalent to the above explanation. controller, as depicted by the dashed phantom line 18 in FIG. Note that in FIG. 5a, in order for a key to gain dominance 4. Moreover, although the array of keys 12 is depicted as 10 over an already active key, it must e being a simple linear array, it will be appreciated by one who measured signal level by a small added amount 'k', as shown reads the complete disclosure contained herein that many in Step 30 to prevent selection dithering. Although the value other sorts of arrays can be used and will encompass, without kis depicted as an additive constant, it can also be determined being limited to, arrays used as computer keyboards, keypads as a percentage of the signal level of the active key, or by any of the sort commonly used in telephony and automated bank- 15 of a number of other methods. The incremental value 'k'can ing, cash register data input keyboards, etc., as well as various also be zero, i.e., nothing is added or subtracted, although this other configurations discussed in conjunction with FIG. 3. would tend to make the decision process unstable should The addition of counters 14, or of the logical function there be any small amount of signal noise which would intro- equivalent thereof, when used in the accordance with the duce dithering between two competing keys. Finally the key teachings of this disclosure, can remove or resolve ambigu- 20 K1 can gain dominance in Step 33 if the TC is reached, and ities by methods involving comparison of signal strengths when it does so it forces all other active keys to become from various keys 12. This process involves examining the inactive and resets their DI counters. differences over one or more sequential signal samples. Turning off a key can be forced via a different key winning Turning now to FIGS. 5a and 5b, one finds flow charts in its Step 33, as shown in FIG. 5a, or it can be carried out depicting a preferred method of the invention for operating 25 according to the method depicted in FIG. 5b. Whether a key the apparatus 10 so as to suppress extraneous key signals or to remains on, in the absence of any other keys with larger otherwise resolve keying ambiguities. This method may be signals (FIG. 5a), is determined by whether the key's signal carried out by a microprocessor 18 operating under control of change remains above a hysteresis level. In Step 35, the a program stored in a, preferably, non-volatile memory, or determination is made if the signal is below the hysteresis may be carried out by means of discrete circuit elements 30 point, and if so the DI is reduced in value by some known connected to provide hardwired logic. Although the flow amount 'Z' (Step 36). If the DI count falls to zero, the key is charts of FIGS. 5a and 5b depict operation in terms of a single made inactive (Step 38). On the other hand, if the signal sensor key 1 (variously labeled "Key 1" or "K1") with asso change remains above the threshold level, the DI counter is ciated signal level S1 and associated Detection Integrator increased again to its limit TC (step 40). If the signal falls DI1, it will be understood that this simplification is solely in 35 between the threshold and the hysteresis level, the DI counter the interest of clarity of presentation and that an algorithm remains unchanged. controlling an actual keyboard could carry out substantially It should be noted that the case where TC=1 also works the depicted method for each of the N keys in a parallel with the flow of FIGS. 5a and 5b. fashion. There are, of course, many possible variations and exten- The depicted method relies on iterated comparisons of 40 sions of the procedure sketched out in FIG. 4 and FIGS. 5a,b. sensor outputs, and selects a single sensor output to become For example, one may consider a rare case in which a user active or 'on' based on that sensor both having an output in brings his or her finger up to a keyboard so that the point of excess of a detection threshold for some selected number of touch is exactly between two keys. In this case, one could counter cycles (which may be one) and thereafter having the modify the depicted process to either select just one of those highest output of all the sensors in the array that have also 45 keys (e.g., by means of a known pseudo-random number exceeded the detection threshold for the selected number of selection algorithm, or by sample sequence order) or by sup- cycles of the counters. It will be recognized that one could pressing the output of both keys until the user move his or her choose to clock all the counters in parallel in order to achieve finger enough that one of the two keys had a higher output this, or that one could scan through the counters and operate than the other. them one at a time in rapid succession so as to provide the 50 Although the present invention has been described with selected number of counter cycles for each sensor within a respect to several preferred embodiments, many modifica- sufficiently short time period that a user could not perceive a tions and alterations can be made without departing from the delay in operation of the keyboard. invention. Accordingly, it is intended that all such modifica- A signal Si, acquired from sensor key K1 (Ste p 24), is tions and alterations be considered as within the spirit and compared with a selected signal threshold value (Step 26). If 55 scope of the invention as defined in the attached claims. Si is less than the threshold value, the value, DI1, in the DI associated with K1 is decremented by a selected amount (Z) What is claimed is: or otherwise reduced (Step 28) if it is greater than zero. If the 1. An apparatus comprising: value S1 is at or above its detection threshold, it is then plurality of keys; compared against all other signals Sj in Step 29. If it has the 60 control logic operatively coupled to the plurality of keys strongest change in signal due to touch, subject to a possible and configured to: non-dithering bias value 'k' if another key is active (Step 30) analyze, to determine a first active key, respective first then counter DI1 can increment (Step 31). If the condition of signal values of the plurality of keys; Step 30 is not met, DI1 is decremented or otherwise reduced assign, based at least on the respective first sensor values of ounter DI1 equals terminal count value 65 the plurality keys, a first key as the first active key; and TC (Step 32) does the key become active or ON in Step 33. analyze, to determine a second active key, respective sec- When it does so the control logic forces all other active keys ond signal values of the plurality of keys, the analysis, to brin 5 US 9,024,790 B2 10 determine the second active key, ofthe respective second mine the second active key, of the respective second signal values of the plurality of keys being biased in signal values of the plurality of keys being biased in favor of the first key. favor of the first key. 2. The apparatus of claim 1, wherein each key comprises a 14. The logic of claim 13, wherein the respective sensor respective capacitive proximity sensor. 5 values are representative of a respective capacitance of a 3. The apparatus of claim 1, wherein at least one key of the respective key of the plurality of keys. plurality of keys comprises a guard ring disposed around at 15. The logic of claim 13, wherein at least one key of the least another key of the plurality of keys. plurality of keys comprises a guard ring disposed about at 4. The apparatus of claim 1, wherein the control logic is least one other of key of the plurality keys. configured to bias the analysis, to determine the second active 10 16. The logic of claim 13, comprising biasing the analysis, key, of the respective second signal values of the plurality of to determine the second active key, of the respective second keys in favor of the first key by increasing the respective signal values of the plurality of keys in favor of the first key by sensor value associated with the first key. 5. The apparatus of claim 1, wherein each of the plurality of increasing the respective sensor value of the first key. keys has an associated counter and the control logic is con- 15 s 17. The logic of claim 13, configured when executed to figured to bias the analysis, to determine the second active perform operations comprising decreasing, when analyzing, key, of the respective second signal values of the plurality of to determine a second active key, respective second signal keys in favor of the first key by changing a value stored in at values of the plurality of keys, the respective sensor values least one of the counters. associated with all each of the keys other than the first key. 6. The apparatus of claim 1, wherein the control logic 2018. The logic of claim 13, wherein each key of the plurality comprises a microcontroller. of keys has an associated counter and biasing the analysis, to 7. A method comprising: determine the second active key, of the respective second analyzing, to determine a first active key, respective first signal values of the plurality of keys in favor of the first key sensor values of a plurality of keys; comprises changing a value stored in at least one of the assigning, based at least on the respective sensor values of 25 counters. the plurality keys, a first key as the first active key; and 19. The apparatus of claim 1, wherein the control logic is analyzing, to determine a second active key, respective configured to assign the first key as the second active key. second signal values of the plurality of keys, the analy- 20. The apparatus of claim 1, wherein the control logic is sis, to determine the second active key, of the respective configured to assign, based at least on respective first sensor second signal values of the plurality of keys being biased 30 values of the plurality keys, the first key as the first active key in favor of the first key. based on: 8. The method of claim 7, wherein the respective sensor the respective first sensor value of the first key exceeding a values are representative of a respective capacitance of a threshold; and respective key of the plurality of keys. 9. The method of claim 7, wherein at least one key of the 35 the respective first sensor value of the first key exceeding plurality of keys comprises a guard ring disposed about at the respective sensor values of the other keys in the least one other key of the plurality of keys. plurality of keys. 10. The method of claim 7, comprising biasing the analy- 21. The apparatus of claim 1, wherein the control logic is sis, to determine the second active key, of the respective configured to assign, based at least on respective second second signal values of the plurality of keys in favor of the 40 sensor values of the plurality keys, a second key as the second first key by increasing the respective sensor value of the first active key based at least on the respective second sensor value key. of the second key exceeding the respective second sensor 11. The method of claim 7, comprising decreasing, when value of the first active key by a particular amount, the first analyzing, to determine a second active key, respective sec- key and the second key being different keys. ond signal values of the plurality of keys, the respective 45 22. The method of claim 7, comprising assigning the first sensor values associated with each of the keys other than the key as the second active key. first key. 23. The method of claim 7, comprising assigning, based at 12. The method of claim 7, wherein each key of the plu- least on respective first sensor values of the plurality keys, the rality of keys has an associated counter and biasing the analy- first key as the first active key based on: sis, to determine the second active key, of the respective 50 the respective first sensor value of the first key exceeding a second signal values of the plurality of keys in favor of the threshold; and first key comprises changing a value stored in at least one of the respective first sensor value of the first key exceeding the counters. the respective sensor values of the other keys in the 13. Logic embodied in a non-transitory computer-readable medium, the logic configured when executed to perform 55 plurality of keys. operations comprising: 24. The method of claim 7, comprising assigning, based at analyzing, to determine a first active key, respective first least on respective second sensor values of the plurality keys, a second key as the second active key based at least on the sensor values of a plurality of keys; assigning, based at least on the respective sensor values of respective second sensor value of the second key exceeding the respective second sensor value of the first active key by a the plurality keys, a first key as the first active key; and 60 analyzing, to determine a second active key, respective particular amount, the first key and the second key being different keys. second signal values of the plurality of keys, the first key being biased during the analysis, the analysis, to deter- 5 US 9,024,790 B2 Page 2 Related U.S. Application Data continuation-in-part of application No. 11/160,885, filed on Jul. 14, 2005, now Pat. No. 7,256,714, which is a continuation of application No. 10/617,602, filed on Jul. 11, 2003, now Pat. No. 6,993,607. (60) Provisional application No. 60/597,851, filed on Dec. 21, 2005, provisional application No. 60/395,368, filed on Jul. 12, 2002. 7,875,814 B2 1/2011 Chen 7,920,129 B2 4/2011 Hotelling 8,031,094 B2 10/2011 Hotelling 8,031,174 B2 10/2011 Hamblin 8,040,326 B2 10/2011 Hotelling 8,049,732 B2 11/2011 Hotelling 8,179,381 B2 5/2012 Frey 8,217,902 B2 7/2012 Chang 8,723,824 B2 5/2014 Myers 2004/0008129 Al 1/2004 Philipp 2004/0104826 A1 6/2004 Philipp 2008/0309635 Al 12/2008 Matsuo 2009/0315854 Al 12/2009 Matsuo 2012/0242588 AL 9/2012 Myers 2012/0242592 A1 9/2012 Rothkopf 2012/0243151 AL 9/2012 Lynch 2012/0243719 AL 9/2012 Franklin 2013/0076612 Al 3/2013 Myers OTHER PUBLICATIONS (51) Int. Cl. GO6F 3/044 HO3K 17/96 (2006.01) (2006.01) (56) References Cited U.S. PATENT DOCUMENTS 4,920,343 A 5,508,700 A 5,933,102 A 6,657,616 B2 7,487,461 B2 7,663,607 B2 7,864,503 B2 4/1990 Schwartz 4/1996 Taylor et al. 8/1999 Miller et al. 12/2003 Sims 2/2009 Zhai et al. 2/2010 Hotelling 1/2011 Chang The Electroquasistatics of the Capacitive Touch Panel, May/Jun. 1990 IEEE, vol. 26, No. 3, P.T. Krein and R.D. Meadows Office Action (and English translation) for CN 200600528529, dated Jan. 19, 2011. U.S. Appl. No. 61/454,936, filed Mar. 21, 2011, Myers. U.S. Appl. No. 61/454,950, filed Mar. 21, 2011, Lynch. U.S. Appl. No. 61/454,894, filed Mar. 21, 2011, Rothkopf. 5 U.S. Patent May 5, 2015 Sheet 1 of 7 US 9,024,790 B2 Doda. FIG. 1A 5 U.S. Patent May 5, 2015 Sheet 2 of 7 US 9,024,790 B2 FIG. 10 – 2 1 Signal Strength Threshold Key # ------ 2 --- 1 - FIG. 1B Signal Strength Threshold Key # US 9,024,790 B2 В А U90UL DODOL ola ODOL OOOOOL 1OOOOO OOOOO OOOOOL "ODODOL "OOOOOL DOOOOL OD UUDUL OOOOOL OOODOL OOL OOOOL OOO JODOOD OOOL ODOL OOOO 30 Sheet 3 of 7 SSL 1.OOOOO .,0000or OOOL OOOO 5 .OOOOO -OOOOOO DODOL OOOOO ODO ODO ODDOOR OOOOO OOOOOO OOOOO FIG. 2 .OOOOO May 5, 2015 DOO OOOOL OOOO ODODOL ODOO ODOOL OOOOO OOOOO OOO ODODO TOODOO ODDOO OOOOO. OOOOO OOOOO. 20OOOD. OOOOO. 200DOO 100OOOL OODOO DOO OOOOO. OOOOO OO. OODOO DOODL OL DOL DOOL OOOL OOOOOL "OOOOOL O0OOOL "OOOOOL OOOOOL OOOOL OOOOOL "OOOOOL OOOOOL "OOOOO 0000or .OOOOOR DO U.S. Patent 5 U.S. Patent May 5, 2015 Sheet 4 of 7 US 9,024,790 B2 JOOor JO OOOO Q00 DOO JOOOO JODOC 000 JDOO JDOO JODOC JODOC JODOC 1000r Jooor JOoor JDOO JOOor JODOC Jooor JOOO .000O|D JOOO .0000 .000or JODOC Jooor,000 JODOC o'ongs Joor .000 2000r .OOOO Jooor Door .DOOO .O0oor .0000 .OOOOT .DDDD" .O0DOC .OOOO .OOOO .OOOO- .000 .000 DOO JO000 .OOOO ODDO ODDOT JOOOO .OOOO JOOOO ODOO JOOOO 0 000 JOOOO 000- JOOOO JOODO JOODO JODID - GOODAL TOUUD FIG. 3 U.S. Patent Key N 17 Signal 1 Signal 2 Compare Logic Vt1 - Vt2- VIN (threshold) mestones Bohr 15 to May 5, 2015 - Signal N 15 ... 14 M14 Counter Logic 1 Cik Control T.C. Counter Logic 1 Cik Control T.C. Counter Logic 1 Cik Control T.C. 5 Max Signal Key Number Sheet 5 of 7 Clock Clock Control Terminal Count Control Terminal Count Clock Control Terminal Count Control Logic 16 18 Result Key Number FIG. 4 US 9,024,790 B2 5 U.S. Patent May 5, 2015 Sheet 6 of 7 US 9,024,790 B2 Start K1 Inactive or Acquire S1 Signal for Key K1 Reset 267 < 51> Threshold DI1 = DI1 - Z lim 299 Y YES L 28 Compare S1 with Sj all j All other Sj 30 < NO. 51 < sj + K all j YES 317 DI1 = D11 + 1 lim T.C. 327 < 011€T.C. NO 33-7 Y YES K1 = ON KJ = OFF, J #11 Clear DIJ, J # 1 To K1 Active FIG. 5A 5 U.S. Patent May 5, 2015 Sheet 7 of 7 US 9,024,790 B2 Key K1 Active Acquire New S1 Signal for Key K1 < > is S 1 > Threshold hysteresis? DI1 = DI1 - Z limo 397 YES is S 1 2 Threshold ? < D1120 NO 407 YES YES 38 DI1 = DI1 + 1 lim. T.C. Turn K1 OFF To Key K1 Inactive FIG. 5B