PATENT DOCUMENT

Publication Number: US-10042486-B1
Application Number: US-201414515390-A
Country: US
Kind Code: B1

Title: Dynamic demodulation waveform adjustment for tonal noise mitigation

Abstract:
A touch controller on a touch sensitive device configured to generate a dynamic demodulation waveform so as to minimize the effects on a signal to noise ratio caused by a tonal noise is disclosed. The demodulation waveform can be turned off for finite durations so as to minimize the probability that a transitional voltage of the tonal noise source is included in the demodulation result.

Claims:
What is claimed is: 
     
       1. A touch controller comprising:
 a processor capable of:
 generating a demodulation waveform; 
 determining a characteristic of a received signal from sense circuitry configured to sense a touch sensor panel; 
 adjusting the demodulation waveform to generate an adjusted demodulation waveform based on the determined characteristic of the received signal, wherein adjusting the demodulation waveform, based on the determined characteristic of the received signal comprises turning off the demodulation waveform for one or more durations within each period of the adjusted demodulation waveform and turning on the demodulation waveform for a remainder of each period; 
 mixing the adjusted demodulation waveform with a second received signal to produce a mixed signal; and 
 using the mixed signal to determine a touch at the touch sensor panel. 
 
 
     
     
       2. The touch controller of  claim 1 , wherein the determined characteristic of the received signal comprises a characteristic of a noise source. 
     
     
       3. The touch controller of  claim 2 , wherein the noise source comprises a tonal noise source. 
     
     
       4. The touch controller of  claim 1 , further comprising:
 the sense circuitry coupled to the processor, wherein the sense circuitry is configured to sense a touch signal from the touch sensor panel and wherein the received signal comprises the touch signal. 
 
     
     
       5. The touch controller of  claim 4 , wherein the sense circuitry is configured to sense the touch signal from a sense line of a mutual capacitance touch sensor panel. 
     
     
       6. The touch controller of  claim 4 , wherein the sense circuitry is configured to sense the touch signal from a self-capacitance touch electrode of a self-capacitance touch sensor panel. 
     
     
       7. The touch controller of  claim 1 , wherein the one or more durations are durations during which the demodulation waveform has signal energy lower than a signal energy at other durations. 
     
     
       8. The touch controller of  claim 1 , wherein the one or more durations coincide with one or more transitional voltages in a noise source. 
     
     
       9. The touch controller of  claim 2 , wherein:
 the processor is further capable of determining a frequency of the noise source, and 
 adjusting the demodulation waveform based on the determined characteristic of the received signal comprises adjusting the demodulation waveform based on the determined frequency of the noise source. 
 
     
     
       10. A method of demodulating a signal, the method comprising:
 generating a demodulation waveform; 
 determining a characteristic of a received signal from sense circuitry configured to sense a touch sensor panel, wherein the determined characteristic of the received signal comprises a characteristic of a tonal noise source; 
 adjusting the demodulation waveform to generate an adjusted demodulation waveform based on the determined characteristic of the received signal, wherein adjusting the demodulation waveform, based on the determined characteristic of the received signal comprises turning off the demodulation waveform for one or more durations within each period of the adjusted demodulation waveform and turning on the demodulation waveform for a remainder of each period; 
 mixing the adjusted demodulation waveform with a second received signal to produce a mixed signal; and 
 using the mixed signal to determine a touch at the touch sensor panel. 
 
     
     
       11. The method of  claim 10 , further comprising sensing a touch signal from the touch sensor panel, wherein the received signal comprises the touch signal. 
     
     
       12. The method of  claim 11 , wherein sensing the touch signal comprises sensing the touch signal from a sense line of a mutual capacitance touch sensor panel. 
     
     
       13. The method of  claim 11 , wherein sensing the touch signal comprises sensing the touch signal from a self-capacitance touch electrode of a self-capacitance touch sensor panel. 
     
     
       14. The method of  claim 10 , wherein the one or more durations are durations during which the demodulation waveform has signal energy lower than a signal energy at other durations. 
     
     
       15. The method of  claim 10 , wherein the one or more durations coincide with one or more transitional voltages in a noise source. 
     
     
       16. The method of  claim 10 , further comprising determining a frequency of the noise source, wherein adjusting the demodulation waveform based on the determined characteristic of the received signal comprises adjusting the demodulation waveform based on the determined frequency of the noise source. 
     
     
       17. A non-transitory computer readable storage medium having stored thereon a set of instructions for demodulating a signal, that when executed by a processor causes the processor to:
 generate a demodulation waveform; 
 determine a characteristic of a received signal from sense circuitry configured to sense a touch sensor panel; 
 adjust the demodulation waveform to generate an adjusted demodulation waveform based on the determined characteristic of the received signal, wherein adjusting the demodulation waveform, based on the determined characteristic of the received signal comprises turning off the demodulation waveform for one or more durations within each period of the adjusted demodulation waveform and turning on the demodulation waveform for a remainder of each period; 
 mix the adjusted demodulation waveform with a second received signal to produce a mixed signal; and 
 use the mixed signal to determine a touch at the touch sensor panel. 
 
     
     
       18. The computer readable storage medium of  claim 17 , wherein the determined characteristic of the received signal comprises a characteristic of a noise source. 
     
     
       19. The computer readable storage medium of  claim 18 , wherein the instructions further cause the processor to:
 determine a frequency of the noise source, wherein adjusting the demodulation waveform based on the determined characteristic of the received signal comprises adjusting the demodulation waveform based on the determined frequency of the noise source. 
 
     
     
       20. The computer readable storage medium of  claim 17 , wherein the one or more durations coincide with one or more transitional voltages in a noise source. 
     
     
       21. The computer readable storage medium of  claim 18 , wherein the noise source comprises a tonal noise source. 
     
     
       22. The computer readable storage medium of  claim 18 , wherein the instructions further cause the processor to:
 sense a touch signal from the touch sensor panel, wherein the received signal comprises the touch signal. 
 
     
     
       23. The computer readable storage medium of  claim 17 , wherein the one or more durations are durations during which the demodulation waveform has signal energy lower than a signal energy at other durations.

Description:
FIELD OF THE DISCLOSURE 
     This relates generally to the shaping/adjustment of a demodulation waveform in order to mitigate tonal noises on an electronic device. 
     BACKGROUND OF THE DISCLOSURE 
     Many types of input devices are available for performing operations in a computing system, such as buttons or keys, mice, trackballs, joysticks, touch sensor panels, touch screens, and the like. Touch screens, in particular, are becoming increasingly popular because of their ease and versatility of operation as well as their declining price. Touch screens can include a touch sensor panel, which can be a clear panel with a touch-sensitive surface, and a display device such as a liquid crystal display (LCD) that can be positioned partially or fully behind the panel so that the touch-sensitive surface can cover at least a portion of the viewable area of the display device. Touch screens generally allow a user to perform various functions by touching (e.g., physical contact or near-field proximity) the touch sensor panel using a finger, stylus or other object at a location often dictated by a user interface (UI) being displayed by the display device. In general, touch screens can recognize a touch event and the position of the touch event on the touch sensor panel, and the computing system can generate touch images and then interpret the touch images in accordance with the display appearing at the time of the touch event, and thereafter can perform one or more actions based on the touch image. 
     Electronic devices in general can be susceptible to tonal noises that can be coupled to the device via proximal electronics such as an external charger. In the instance of a touch input device, tonal noise can generate a “false touch” on the screen; in other words, the device will determine that a touch or proximity event has occurred when none exists. In some cases, these tonal noises can additionally or alternatively cause error(s) in touch position calculations, such as jittering of the touch position with time, that can cause inaccuracies in touch input when accurate touch position calculation is important (e.g., when user input elements are spaced close together on the screen, such as in an on-screen keyboard). Furthermore, tonal noise can also cause a device to ignore an actual touch or proximity event. For example, mutual capacitance touch sensor panels can be formed from a matrix of drive and sense lines of a substantially transparent conductive material such as Indium Tin Oxide (ITO). The lines are often arranged orthogonally on a substantially transparent substrate. Tonal noise can be coupled into the matrix of drive lines and sense lines, causing signals to appear that can be misinterpreted as a touch or proximity event. Also, tonal noise can be coupled into the matrix of drive and sense lines causing signals to appear as negative touches, such that when a real touch occurs, it is not detected. The false touches or undetected touches can lead to an overall degradation of the user experience in that the device will register touches that the user did not intend, and furthermore, may fail to recognize actual touches intended by a user of the device. 
     SUMMARY OF THE DISCLOSURE 
     This relates to a touch input device that can dynamically adjust a demodulation waveform in response to a detected tonal noise such that the performance degradation caused by the tonal noise can be minimized. 
     A demodulation waveform can be adjusted such that the probability that a transitional edge of a tonal noise waveform is included in the final demodulated signal is decreased. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an exemplary mutual capacitance touch sensor panel in a no-touch condition according to disclosed examples. 
         FIG. 2  illustrates an exemplary drive line and sense line pairing and their associated electronics according to examples of the disclosure. 
         FIGS. 3 a - d    illustrate various signals found in the circuit depicted at  FIG. 2 . 
         FIGS. 4 a - d    illustrate various signals found in the circuit depicted at  FIG. 2  when a dynamic demodulation waveform is utilized. 
         FIG. 5  illustrates an exemplary computing system that can include one or more of the examples described above. 
         FIGS. 6 a - d    illustrate various electronic devices that can include one or more of the examples described above. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description of examples, reference is made to the accompanying drawings which form a part hereof, and in which it is shown by way of illustration specific examples that can be practiced. It is to be understood that other examples can be used and structural changes can be made without departing from the scope of the disclosed examples. 
     This relates to the use of a dynamic demodulation waveform to minimize the degradation to a signal to noise ratio (SNR) caused by tonal noise that is coupled into a touch sensor panel from, for example, electronics proximal to the device. Noise from an LCD, an AC adapter, and other sources can be tonal noises. When a tonal noise source is detected, the device can adjust a demodulation waveform to minimize the likelihood that a transitional edge of the tonal noise source is included in the accumulated demodulation result. It is understood that tonal noises, as used in this disclosure, can refer generally to any periodic and/or repeating noise waveforms. 
     Although examples disclosed herein may be described and illustrated herein in terms of mutual capacitance touch sensor panels, it should be understood that the examples are not so limited, but are additionally applicable to self-capacitance sensor panels, and both single- and multi-touch sensor panels in which demodulation can occur. For example, a self-capacitance based touch system can include a matrix of small, individual plates of conductive material that can be referred to as touch pixel electrodes. For example, a touch screen can include a plurality of individual touch pixel electrodes, each touch pixel electrode identifying or representing a unique location on the touch screen at which touch or proximity (i.e., a touch or proximity event) is to be sensed, and each touch pixel electrode being electrically isolated from the other touch pixel electrodes in the touch panel/screen. Such a touch screen can be referred to as a pixelated self-capacitance touch screen. During operation, a touch pixel electrode can be stimulated with an AC waveform, and the self-capacitance to ground of the touch pixel electrode can be measured. As an object approaches the touch pixel electrode, the self-capacitance to ground of the touch pixel electrode can change. This change in the self-capacitance of the touch pixel electrode can be detected and measured by the touch sensing system to determine the positions of multiple objects when they touch, or come in proximity to, the touch screen. In some examples, the electrodes of a self-capacitance based touch system can be formed from rows and columns of conductive material, and changes in the self-capacitance to ground of the rows and columns can be detected, similar to above. 
       FIG. 1  illustrates an exemplary mutual capacitance touch sensor panel in a no-touch condition, i.e., when there are presently no touches at the panel, according to various examples of the disclosure. In the example of  FIG. 1 , touch sensor panel  124  can include an array of nodes  126  that can be formed at the crossings of rows of drive lines  101  (D 0 -D 3 ) and columns of sense lines  102  (S 0 -S 3 ). Each node  126  can have an associated mutual capacitance Csig  114  when the drive line  101  forming the node is stimulated with a stimulation signal Vstm  116 . Each node  126  can also have an associated stray capacitance Cstray when the drive line  101  forming the node is not stimulated with a stimulation signal Vstm  116  but is connected to a DC voltage. In this example, drive line D 0  can be stimulated with stimulation signal  116  (Vstm), forming mutual capacitance Csig  114  at the nodes  126  that are formed at the drive line D 0  and the sense lines S 0 -S 3  crossings. One or more drive lines  101  can be stimulated at any given time (i.e., in some examples, more than one drive line  101  may be stimulated concurrently). 
       FIG. 2  illustrates an exemplary drive line and sense line pairing and their associated electronics according to examples of the disclosure. A drive line  204  can be capacitively coupled to a sense line  206 . The drive line  204  can be coupled to multiple sense lines, and likewise a sense line  206  can be coupled to multiple drive lines; however, for the purpose of illustration, only one such pairing is illustrated. The drive line  204  can be stimulated with an AC or DC voltage source by stimulation circuitry  202 , as described above. As described above, a portion of the stimulation signal transmitted by the drive line  204  can be capacitively coupled to sense line  206 . When a finger or other external object comes into contact with or in close proximity to the drive line/sense line pairing (i.e., touch node), the amount of signal coupled between drive line  204  and sense line  206  can change. This change can be detected by sense circuitry  230  that can be coupled to each sense line such as sense line  206 . Analogously, in the case of a self-capacitance touch sensor panel, sense circuitry  230  can detect the change in the self-capacitance of a self-capacitance touch electrode (e.g., touch pixel electrode) caused by a finger or other object being in contact with or in proximity to the self-capacitance touch electrode. 
     Sense circuitry  230  can include analog front end circuitry  216  for performing analog signal processing functions such as buffering. The data collected from the sense line  206  can then be converted to a digital signal via analog-to-digital converter (ADC)  218 . The output of ADC  218  can then be mixed by mixer  220  with a signal generated by a signal generator  222 . The signal generated by the signal generator can be used to perform homodyne mixing on the signal in order to frequency shift the incoming signal into a baseband signal. The output of mixer  220  can then be inputted into mixer  224  in which a windowing function provided by window generator  226  can be mixed with the signal. The output of mixer  224  can then be fed into an accumulator  228 , which can act as the digital equivalent of a low pass filter. 
     In some examples, proximal electronics, such as an AC adapter used to charge the device, can cause interference with the sense circuitry. As illustrated in FIG.  2 , proximal electronics can act as a noise source  210  that can be capacitively coupled to the touch sensor panel through  208 . In some examples, the noise source  210  can provide a tonal periodic signal that can ultimately be coupled into the sense line  206  via drive line  204 . Noise source  210  can similarly be coupled to a self-capacitance touch electrode in a self-capacitance touch sensor panel. 
       FIGS. 3 a - d    illustrate various signals found in the circuit depicted at  FIG. 2 , according to examples of the disclosure.  FIG. 3 a    illustrates an example signal  302  that can be transmitted by stimulation circuitry  202  of  FIG. 2  to drive line  204 . The signal  302  can be an AC sinusoidal signal of a certain frequency (denoted as f stim ) and amplitude.  FIG. 3 c    illustrates an example signal  322  that can be used as a demodulation waveform. The signal  322  can be generated by signal generator  222  of  FIG. 2 . The signal  322  can by synchronized with signal  302  of  FIG. 3 a    such that the two signals can have the same frequency (denoted as f demod ) and phase in order to achieve homodyne mixing of the signal received by mixer  220 . Though the examples of the disclosure may be described with reference to signals  302  and  322  being synchronized and having the same frequency, it is understood that this need not be the case, and the scope of the disclosure is not so limited. For example, the examples of the disclosure may implement I/Q demodulation in which f stim  (frequency of signal  302 ) may be equal or close to f demod  (frequency of signal  322 ) such that perfect synchronization of signals  302  and  322  may not be required.  FIG. 3 b    illustrates an example tonal noise signal  310 , such as one produced by noise source  210  of  FIG. 2 . The tonal noise signal  310 , in this example, can be a periodic square wave of a certain frequency (denoted as f noise ) and amplitude. 
     After both the coupled stimulation signal  302  and the tonal noise  310  are mixed with the demodulation waveform  322  at mixer  220  in  FIG. 2 , the frequency response of the resultant signal can appear as depicted in  FIG. 3 d   . As illustrated, frequency response  330  can have two signals. The first signal, depicted at  332 , can represent the mixture of the stimulation signal  302  and the demodulation waveform  322 . The frequency of the signal  332  can be the difference between the stimulation frequency f stim  and the demodulation f demod . In the case where f stim  and f demod  are the same frequency, the signal  332  can be a DC signal. The second signal, depicted at  334 , can represent the mixture of the tonal noise signal  310  and the demodulation waveform  322 . The frequency of the signal  334  can be the difference between the stimulation frequency f stim  and the noise frequency f noise . 
     If signal  334  is close enough in frequency to signal  332 , during the accumulation that takes place at accumulator  228  in  FIG. 2 , the energy of signal  334  can be included in the accumulator result. This can lead to a degradation of the signal-to-noise ratio for the touch sensor panel. 
       FIGS. 4 a - d    illustrate various signals found in the circuit depicted at  FIG. 2  when a dynamic demodulation waveform is applied.  FIGS. 4 a  and 4 b    (and signals  402  and  410 ) can be identical to  FIGS. 3 a  and 3 b    (and signals  302  and  310 ) discussed above.  FIG. 4 c    can illustrate an exemplary dynamically adjusted waveform  422  according to examples of the disclosure. The waveform  422  can be similar to the waveform  322  depicted in  FIG. 3 c   , except the signal can be turned “off” (i.e., held at substantially 0V) for one or more durations (in some examples, predetermined durations). The durations during which waveform  422  can be turned off can be durations during which the waveform has relatively low signal energy, and the durations during which the waveform can be turned on can be durations during which the waveform has relatively high signal energy (e.g., between π/2 and 3π/4 and between 3π/2 and 7π/4 for a sine-based waveform). Dashed line  436  illustrates a “standard demodulation waveform,” such as waveform  322  illustrated in  FIG. 3 c   , and is only depicted in  FIG. 4 c    so as to provide a comparison with the dynamically adjusted demodulation waveform  422 . With respect to the “standard demodulation waveform,” during time period T 1 , the dynamic waveform  422  can be turned “off”. When the period ends, the dynamic waveform  422  can be turned back on to the value it would have had had the waveform not been turned off. This process can repeat at T 2 , T 3 , T 4  and so on. 
     The results produced by using a dynamic waveform, such as the one described above, for demodulating touch signals will now be described. A tonal noise signal, such as the one depicted in  FIG. 4 b    at  410 , can degrade the touch system&#39;s signal-to-noise ratio (SNR) due to transitional voltages that may exist in the tonal noise signal, such as those depicted at  434  and  432 . By selectively turning on and off the demodulation waveform  422 , the probability that a transitional edge of the tonal noise (e.g., edges  432  and  434 ) will be mixed into the demodulation result can be reduced. As depicted, if a transitional edge of the tonal noise waveform coincides with a period of time when the demodulation waveform is turned off (e.g., T 1 ), then the effect of the edge may not be included in the demodulation result. 
     The probability that a transitional edge will be included in a demodulation result can be a function of a duration during which the demodulation waveform is “turned off.” As an example, if the probability that a transitional edge appears in the tonal noise waveform is uniform over time, and if during one integration period T there are four periods of time T 1 -T 4  during which the demodulation waveform is turned off, as depicted in  FIG. 4 c   , assuming that T 1 , T 2 , T 3  and T 4  are of equal duration, then the probability that a transitional edge will be included in the demodulation result can be expressed as:
 
[ T− 4* T 1]/ T   (1)
 
where T equals one integration period, and T 1  represents the duration of one “off” period of the demodulation waveform. As is evidenced by equation 1, the longer the “off” periods are in duration, the less likely it is that a transitional edge of the tonal noise waveform will be included in the demodulation result. It is understood that dynamic waveform  422  is provided by way of example only, and other dynamic waveforms that reduce the probability that a transitional edge of a tonal noise will be included in a demodulation result are also within the scope of the disclosure.
 
     As illustrated in  FIG. 4 d   , using a dynamic demodulation waveform (e.g., waveform  422 ) can have an impact on the frequency content of the demodulation result  430 . Similar to  FIG. 3 d   , the stimulation signal can be mixed with the dynamic demodulation waveform  422  to produce a signal with a frequency of f stim −f demod . However, unlike  FIG. 3 d   , because the dynamic demodulation waveform has periods during which it is turned off, susceptibility bands may appear at harmonic frequencies of the demodulation waveform frequency, as illustrated. These harmonic waveforms may increase or decrease based on the durations of T 1 -T 4 , and thus may act as a constraint on the value of T 1 . Furthermore, as T 1  is increased, there may be signal loss at the demodulation waveform which could also act as a constraint on T 1 . 
     It is understood that while the examples of the disclosure have been provided in the context of turning on and off the demodulation waveform during certain durations of time, other methods can be used to achieve the same or similar results. For example, the demodulation waveform can be ignored or otherwise selectively prevented from affecting the mixed signal during the certain durations of time, and/or the result of the demodulation waveform (e.g., the mixed signal resulting from mixing the demodulation waveform with another waveform (e.g., a touch signal)) can be ignored during the certain durations of time. A person of skill in the art would understand that, based on this disclosure, other schemes can similarly be used to prevent certain portions of a received signal (e.g., touch signal) from affecting a mixed signal resulting from mixing the received signal with a demodulation waveform. 
     In some examples, the device can detect tonal noise, determine a frequency of the tonal noise (in some examples, determine the times of rising and falling edges in the tonal noise), and adjust the dynamic demodulation waveform based on the determined frequency of the tonal noise. For example, the device can set values for T 1 -T 4  based on the determined frequency of the tonal noise so as to reduce the probability that a rising or falling edge in the tonal noise will coincide with a non-zero value of the dynamic demodulation frequency. In some examples, the demodulation waveform can be dynamically adjusted or periodically adjusted to account for changes in the tonal noise. 
       FIG. 5  illustrates exemplary computing system  500  that can implement one or more of the examples described above. Computing system  500  can include one or more panel processors  502  and peripherals  504 , and panel subsystem  506 . Panel subsystem  506  can be referred to as a “touch controller.” Peripherals  504  can include, but are not limited to, random access memory (RAM) or other types of memory or storage, watchdog timers and the like. Panel subsystem  506  can include, but is not limited to, one or more sense channels  508 , which can utilize operational amplifiers that can be configured to minimize saturation time, channel scan logic  510  and driver logic  514 . In some examples, sense channels  508  can include sense circuitry described in this disclosure, such as sense circuitry  230 . Channel scan logic  510  can access RAM  512 , autonomously read data from the sense channels and provide control for the sense channels including calibrating the sense channels for changes in phase correlated with a parasitic capacitance. In some examples, channel scan logic  510  can facilitate adjustment of the dynamic demodulation waveform of the disclosure, as described above. In addition, channel scan logic  510  can control driver logic  514  to generate stimulation signals  516  at various frequencies and phases that can be selectively applied to drive lines of touch sensor panel  524 . In some examples, driver logic  514  can include stimulation circuitry as described in this disclosure, such as stimulation circuitry  202 . In some examples, panel subsystem  506 , panel processor  502  and peripherals  504  can be integrated into a single application specific integrated circuit (ASIC). In some examples, panel subsystem  506  and panel processor  502  can together be referred to as a “touch controller.” In some examples, panel processor  502  can facilitate adjustment of the dynamic demodulation waveform of the disclosure, as described above. 
     Touch sensor panel  524  can include a capacitive sensing medium having a plurality of drive lines and a plurality of sense lines, although other sensing media can also be used. Each intersection of drive and sense lines can represent a capacitive sensing node and can be viewed as picture element (node)  526 , which can be particularly useful when touch sensor panel  524  is viewed as capturing an “image” of touch. Each sense line of touch sensor panel  524  can drive sense channel  508  (also referred to herein as an event detection and demodulation circuit) in panel subsystem  506 . The drive and sense lines can additionally or alternatively be configured to act as individual electrodes in a self-capacitance touch sensing configuration. Further, in some examples, touch sensor panel  524  can be a pixelated self-capacitance touch sensor panel. 
     Computing system  500  can also include host processor  528  for receiving outputs from panel processor  502  and performing actions based on the outputs that can include, but are not limited to, moving an object such as a cursor or pointer, scrolling or panning, adjusting control settings, opening a file or document, viewing a menu, making a selection, executing instructions, operating a peripheral device coupled to the host device, answering a telephone call, placing a telephone call, terminating a telephone call, changing the volume or audio settings, storing information related to telephone communications such as addresses, frequently dialed numbers, received calls, missed calls, logging onto a computer or a computer network, permitting authorized individuals access to restricted areas of the computer or computer network, loading a user profile associated with a user&#39;s preferred arrangement of the computer desktop, permitting access to web content, launching a particular program, encrypting or decoding a message, and/or the like. Host processor  528  can also perform additional functions that may not be related to panel processing, and can be coupled to program storage  532  and display device  530  such as an LCD display for providing a UI to a user of the device. Display device  530  together with touch sensor panel  524 , when located partially or entirely under the touch sensor panel, can form a touch screen. 
     Note that one or more of the functions described above can be performed by firmware stored in memory (e.g. one of the peripherals  504  in  FIG. 5 ) and executed by panel processor  502 , or stored in program storage  532  and executed by host processor  528 . The firmware can also be stored and/or transported within any non-transitory computer-readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “non-transitory computer-readable storage medium” can be any medium (other than a “transport medium” defined below) that can contain or store the program for use by or in connection with the instruction execution system, apparatus, or device. The computer readable storage medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, a portable computer diskette (magnetic), a random access memory (RAM) (magnetic), a read-only memory (ROM) (magnetic), an erasable programmable read-only memory (EPROM) (magnetic), a portable optical disc such a CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flash memory such as compact flash cards, secured digital cards, USB memory devices, memory sticks, and the like. 
     The firmware can also be propagated within any transport medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “transport medium” can be any medium that can communicate, propagate or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The transport readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic or infrared wired or wireless propagation medium. 
       FIG. 6 a    illustrates exemplary mobile telephone  636  that can include touch screen  624  (e.g., a touch sensor panel and display device), the touch screen including circuitry to employ a dynamic demodulation waveform according to one disclosed example. 
       FIG. 6 b    illustrates exemplary digital media player  640  that can include touch screen  626  (e.g., a touch sensor panel and display device), the touch screen including circuitry employ a dynamic demodulation waveform according to one disclosed example. 
       FIG. 6 c    illustrates exemplary personal computer  644  that can include touch screen  628  (e.g., a touch sensor panel and display), the touch sensor panel and/or display of the personal computer (in examples where the display is part of a touch screen) including circuitry to employ a dynamic demodulation waveform according to one disclosed example. 
       FIG. 6 d    illustrates exemplary tablet computer  648  that can include touch screen  630  (e.g., a touch sensor panel and display screen), the touch sensor panel and/or display of the tablet computer (in examples where the display is part of a touch screen) including circuitry employ a dynamic demodulation waveform according to one disclosed example. The mobile telephone, media player, personal computer and tablet computer of  FIGS. 6 a - d    can reduce the adverse effects of tonal noise on the detection of touch. 
     Although  FIGS. 6 a - d    discuss a mobile telephone, a media player, a personal computer and a tablet computer, respectively, the disclosure is not so restricted, and the touch sensor panel of the disclose can be included in a television or any other device, such as a wearable device, which can benefit from the reduction of adverse effects on the detection of touch caused by a tonal noise source. 
     Therefore, according to the above, some examples of the disclosure are directed to a touch controller comprising: a processor capable of: generating an adjustable demodulation waveform; mixing the adjustable demodulation waveform with a received signal to produce a mixed signal; determining a characteristic of the received signal; adjusting the demodulation waveform based on the determined characteristic of the received signal, wherein adjusting the demodulation waveform comprises, based on the determined characteristic of the received signal, selectively preventing the mixed signal from being affected by the received signal; and using the mixed signal to determine a touch. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the determined characteristic of the received signal comprises a characteristic of a noise source. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the noise source comprises a tonal noise source. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch controller further comprises sense circuitry configured to sense a touch signal on a touch sensor panel, wherein the received signal comprises the touch signal. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the sense circuitry is configured to sense the touch signal from a sense line of a mutual capacitance touch sensor panel. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the sense circuitry is configured to sense the touch signal from a self-capacitance touch electrode of a self-capacitance touch sensor panel. Additionally or alternatively to one or more of the examples disclosed above, in some examples, selectively preventing the mixed signal from being affected by the received signal comprises turning off the demodulation waveform for one or more durations. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the one or more durations are durations during which the demodulation waveform has signal energy lower than a signal energy at other durations. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the one or more durations coincide with one or more transitional voltages in a noise source. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the processor is further capable of determining a frequency of the noise source, and adjusting the demodulation waveform based on the determined characteristic of the received signal comprises adjusting the demodulation waveform based on the determined frequency of the noise source. 
     Some examples of the disclosure are directed to a method of demodulating a signal, the method comprising: generating an adjustable demodulation waveform; mixing the adjustable demodulation waveform with a received signal to produce a mixed signal; determining a characteristic of the received signal; adjusting the demodulation waveform based on the determined characteristic of the received signal, wherein adjusting the demodulation waveform comprises, based on the determined characteristic of the received signal, selectively preventing the mixed signal from being affected by the received signal; and using the mixed signal to determine a touch. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the determined characteristic of the received signal comprises a characteristic of a noise source. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the noise source comprises a tonal noise source. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises sensing a touch signal on a touch sensor panel, wherein the received signal comprises the touch signal. Additionally or alternatively to one or more of the examples disclosed above, in some examples, sensing the touch signal comprises sensing the touch signal from a sense line of a mutual capacitance touch sensor panel. Additionally or alternatively to one or more of the examples disclosed above, in some examples, sensing the touch signal comprises sensing the touch signal from a self-capacitance touch electrode of a self-capacitance touch sensor panel. Additionally or alternatively to one or more of the examples disclosed above, in some examples, selectively preventing the mixed signal from being affected by the received signal comprises turning off the demodulation waveform for one or more durations. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the one or more durations are durations during which the demodulation waveform has signal energy lower than a signal energy at other durations. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the one or more durations coincide with one or more transitional voltages in a noise source. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises determining a frequency of the noise source, wherein adjusting the demodulation waveform based on the determined characteristic of the received signal comprises adjusting the demodulation waveform based on the determined frequency of the noise source. 
     Some examples of the disclosure are directed to a non-transitory computer readable storage medium having stored thereon a set of instructions for generating a dynamically adjustable demodulation waveform on a touch sensor panel, that when executed by a processor causes the processor to: generate an adjustable demodulation waveform; mix the adjustable demodulation waveform with a received signal to produce a mixed signal; determine a characteristic of the received signal; adjust the demodulation waveform based on the determined characteristic of the received signal, wherein adjusting the demodulation waveform comprises, based on the determined characteristic of the received signal, selectively preventing the mixed signal from being affected by the received signal; and using the mixed signal to determine a touch. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the determined characteristic of the received signal comprises a characteristic of a noise source. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the instructions further cause the processor to: determine a frequency of the noise source, wherein adjusting the demodulation waveform based on the determined characteristic of the received signal comprises adjusting the demodulation waveform based on the determined frequency of the noise source. Additionally or alternatively to one or more of the examples disclosed above, in some examples, selectively preventing the mixed signal from being affected by the received signal comprises turning off the demodulation waveform for one or more durations. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the one or more durations coincide with one or more transitional voltages in a noise source. 
     Although the disclosed examples have been fully described with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the disclosed examples as defined by the appended claims.

Metadata:
Filing Date: 20141015
Publication Date: 20180807
Grant Date: 20180807
Priority Date: 20131018
Inventors: SHAHPARNIA, SHAHROOZ
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/05", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0488", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/05", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0488", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04182", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0418", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 63014075