Noise cancellation technique for capacitive touchscreen controller using differential sensing
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
G06F-003/041
G06F-003/044
H03K-017/96
출원번호
US-0199757
(2016-06-30)
등록번호
US-9870097
(2018-01-16)
발명자
/ 주소
Joharapurkar, Ashutosh Ravindra
Le, Jean CauXuan
Viswanathan, Natarajan
Chan, Patrick Yin
출원인 / 주소
QUALCOMM Incorporated
대리인 / 주소
Weaver Austin Villeneuve & Sampson LLP—QUAL
인용정보
피인용 횟수 :
0인용 특허 :
25
초록▼
A differential sensing scheme provides a means for detecting one or more touch events on a touch sensitive device in the presence of incident noise. Instead of sensing one touch sensitive channel, such as a row, column, or single touch sensor, multiple touch sensitive channels are sampled at a time.
A differential sensing scheme provides a means for detecting one or more touch events on a touch sensitive device in the presence of incident noise. Instead of sensing one touch sensitive channel, such as a row, column, or single touch sensor, multiple touch sensitive channels are sampled at a time. By sampling two nearby channels simultaneously and doing the measurement differentially, noise common to both channels is cancelled. The differential sensing scheme is implemented using simple switch-capacitor AFE circuitry. The originally sensed data on each individual channel is recovered free of common-mode noise. The recovered sensed data is used to determine the presence of one or more touch events and if present the location of each touch event on the touch sensitive device.
대표청구항▼
1. An apparatus comprising: a touch sensitive device including a plurality of channels, the apparatus configured to: determine a no touch baseline value for each channel of the plurality of channels by measuring a capacitance of each channel when no touch event is present on any of the plurality of
1. An apparatus comprising: a touch sensitive device including a plurality of channels, the apparatus configured to: determine a no touch baseline value for each channel of the plurality of channels by measuring a capacitance of each channel when no touch event is present on any of the plurality of channels;select one of the plurality of channels as a primary channel;select another of the plurality of channels as a reference channel, the reference channel being different than the primary channel;measure a capacitance of the primary channel;measure a capacitance of the reference channel;determine a measured difference between the measured capacitance of the primary channel and the measured capacitance of the reference channel;determine a baseline difference between the no touch baseline value for the primary channel and the no touch baseline value for the reference channel;determine a delta from baseline for the primary channel and reference channel by calculating a difference between the measured difference and the baseline difference;repeat the steps of selecting one of the plurality of channels as a primary channel, selecting another of the plurality of channels as a reference channel, measuring a capacitance of the primary channel, measuring a capacitance of the reference channel, determining a measured difference between the measured capacitance of the primary channel and the measured capacitance of the reference channel, determining a baseline difference between the no touch baseline value for the primary channel and the no touch baseline value for the reference channel, and determining a delta from baseline for the primary channel and reference channel for each channel in the plurality of channels so that each channel is selected as the primary channel; anddetermine one or more touch events from the determined deltas from baseline calculated for all primary channel and reference channel pairs. 2. The apparatus of claim 1, wherein each channel comprises one or both of a row sensor and a column sensor in the touch sensitive device. 3. The apparatus of claim 1, wherein the touch sensitive device comprises a two-dimensional touch panel. 4. The apparatus of claim 1, wherein the touch sensitive device comprises a one-dimensional virtual slider. 5. The apparatus of claim 1, wherein the primary channel and the reference channel each have common-mode noise that is removed in the determined deltas from baseline. 6. The apparatus of claim 1, Wherein the primary channel and the reference channel are adjacent channels. 7. A non-transitory computer readable medium having software stored thereon, the software including instructions for detecting one or more touch events on a touch sensitive device including a plurality of channels, the instructions causing an apparatus to: determine a no touch baseline value for each channel of the plurality of channels by measuring a capacitance of each channel when no touch event is present on any of the plurality of channels;select one of the plurality of channels as a primary channel;select another of the plurality of channels as a reference channel, the reference channel being different than the primary channel;measure a capacitance of the primary channel;measure a capacitance of the reference channel;determine a measured difference between the measured capacitance of the primary channel and the measured capacitance of the reference channel;determine a baseline difference between the no touch baseline value for the primary channel and the no touch baseline value for the reference channel;determine a delta from baseline for the primary channel and reference channel by calculating a difference between the measured difference and the baseline difference;repeat the steps of selecting one of the plurality of channels as a primary channel, selecting another of the plurality of channels as a reference channel, measuring a capacitance of the primary channel, measuring a capacitance of the reference channel, determining a measured difference between the measured capacitance of the primary channel and the measured capacitance of the reference channel, determining a baseline difference between the no touch baseline value for the primary channel and the no touch baseline value for the reference channel, and determining a delta from baseline for the primary channel and reference channel for each channel in the plurality of channels so that each channel is selected as the primary channel; anddetermine one or more touch events from the determined deltas from baseline calculated for all primary channel and reference channel pairs. 8. The computer readable medium of claim 7, the instructions further causing the apparatus to: recover sensed data from the primary channel and the reference channel after determining the delta from baseline. 9. The computer readable medium of claim 7, the instructions further causing the apparatus to: perform an integration backwards on the determined deltas from baseline calculated for all primary channel and reference channel pairs, wherein the deltas from baseline are sequentially calculated forward starting from a first channel to a last channel, and the integration backwards starts from a last delta from baseline calculated to a first delta from baseline. 10. An apparatus comprising a touch sensitive device including a plurality of channels, the apparatus configured to: determine a no touch baseline capacitance value for each channel of the plurality of channels when no touch event is present on any of the plurality of channels;select two channels from the plurality of channels;determine a baseline difference by calculating a difference between the no touch baseline capacitance value for the selected two channels;measure a capacitance of each of the selected two channels;determine a measured difference by calculating a difference between the measured capacitances of the selected two channels;determine a delta from baseline for the two channels by calculating a difference between the measured difference and the baseline difference;repeat the steps of selecting two channels from the plurality of channels, determining a baseline difference, measuring a capacitance of each of the selected two channels, determining a measured difference and determining a delta from baseline for additional channel pairs in the plurality of channels;recover sensed data from all the delta from baselines for the channel pairs, wherein the recovered sensed data does not include common-mode noise present in the sensed data, anddetermine one or more touch events from the recovered sensed data. 11. The apparatus of claim 10, wherein the capacitances of each of the selected two channels are measured simultaneously. 12. The apparatus of claim 10, wherein each channel is configured having a same shape and size. 13. The apparatus of claim 10, wherein each channel includes one or both of a row sensor or a column sensor in the touch sensitive device.
연구과제 타임라인
LOADING...
LOADING...
LOADING...
LOADING...
LOADING...
이 특허에 인용된 특허 (25)
Maharyta, Andriy; Ryshtun, Andriy; Kremin, Victor, AC line synchronization for capacitive sensing.
Boie Robert A. (Westfield NJ) Ruedisueli Laurence W. (Berkeley Heights NJ) Wagner Eric R. (South Plainfield NJ), Computer mouse or keyboard input device utilizing capacitive sensors.
Sadler, Daniel J.; Cranfill, David B.; Olley, Michael F.; Tashakkor, Eric V.; Wagner, Daniel H., Electronic device and circuit for providing tactile feedback.
Joharapurkar, Ashutosh R.; Chan, Patrick; Allen, David L.; Viswanathan, Natarajan, Method and apparatus for improving dynamic range of a touchscreen controller.
Joharapurkar, Ashutosh R.; Le, Jean C.; Viswanathan, Natarajan; Chan, Patrick, Noise cancellation technique for capacitive touchscreen controller using differential sensing.
Joharapurkar, Ashutosh Ravindra; Le, Jean CauXuan; Viswanathan, Natarajan; Chan, Patrick, Noise cancellation technique for capacitive touchscreen controller using differential sensing.
Joharapurkar, Ashutosh Ravindra; Kodur, Karthikeya; Reddy, Venugopal; Chan, Patrick, System for and method of transferring charge to convert capacitance to voltage for touchscreen controllers.
Joharapurkar, Ashutosh Ravindra; Chan, Patrick; Allen, David L.; Viswanathan, Natarajan, Use of random sampling technique to reduce finger-coupled noise.
※ AI-Helper는 부적절한 답변을 할 수 있습니다.