Sensing device, touch sensing system, and display device

• US 8,907,905 B2
• Filed: 12/16/2011
• Issued: 12/09/2014
• Est. Priority Date: 12/16/2011
• Status: Active Grant

• Current Assignee: Silicon Integrated Systems Corporation (Silicon Integrated Systems Corporation Taiwan)
• Original Assignee: Silicon Integrated Systems Corporation (Silicon Integrated Systems Corporation Taiwan)
• Inventors: Lin, Song Sheng, Chang, Ssu-Wei, Yeh, Ying-Jyh
• Primary Examiner(s): Bolotin, Dmitriy
• Application Number:
  US13/329,076
• Publication Number:
  US 20130154997A1
• Time in Patent Office: 1,089 Days
• Field of Search: 345156-184, 178/18.03, 178/18.05, 178/18.06
• US Class Current: 345/173
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/044 by capacitive means

Abstract

A sensing device placed in a touch sensing system of a display device includes a selector, a sensing module, and a detection module for determining touch signals generated by the touch sensing system. The selector selects two of the touch signals according to at least one selection control signal. The sensing module comprises a first differential amplifier for comparing the selected touch signals and producing a first differential signal according to first control signals. According to second control signals, the detection module receives the first differential signal, generates an averaged sensing value and a reference value, and compares the averaged sensing value with the reference value to produce a second differential signal. Thereby, the touch sensing system uses the second differential signal to generate the first control signals and the second control signals to control the operation of the touch sensing system.

Claims

1. A sensing device for determining N touch signals, wherein N is a positive integer, and the sensing device comprising:

a selector for selecting an ith touch signal and an (i+1)th touch signal from the touch signals according to at least one selection control signal, i is a positive integer from 1 to (N−

1);

a sensing module connecting to the selector in series and comprising;

a first differential amplifier for comparing the selected touch signals and producing a first differential signal according to a plurality of first control signals;

a first sensing line comprising a first switch and a first charge maintenance circuit for receiving the ith touch signal and transmitting the ith touch signal to a first end of the first differential amplifier, wherein the first charge maintenance circuit connects to the first switch in series and receives the ith touch signal when the first switch is closed according to the control of a first part of the first control signals; and

a second sensing line comprising a second switch and a second charge maintenance circuit for receiving the (i+1)th touch signal and transmitting the (i+1)th touch signal to a second end of the first differential amplifier, wherein the second charge maintenance circuit connects to the second switch in series and receives the (i+1)th touch signal when the second switch is closed according to the control of the first part of the first control signals; and

a detection module connecting to the sensing module in series for according to a plurality of second control signals, generating an averaged sensing value and a reference value from the first differential signal and comparing the averaged sensing value with the reference value to produce a second differential signal.

2. The sensing device according to claim 1, wherein the selector is a multiplexer.

3. The sensing device according to claim 1, wherein each of the first charge maintenance circuit and the second charge maintenance circuit comprises a capacitor and a third switch which connects to the capacitor in parallel, the third switches synchronously operate according to the control of a second part of the first control signals.

4. The sensing device according to claim 1, wherein the detection module comprises:

an integrator for integrating the first differential signal to generate the averaged sensing value;

a voltage buffer for receiving the first differential signal to generate the reference value; and

a second differential amplifier for simultaneously receiving the averaged sensing value and the reference value to generate the second differential signal, wherein the integrator and the voltage buffer synchronously operate.

5. The sensing device according to claim 4, wherein the detection module further comprises:

a sensing integrated unit respectively connecting to the integrator in parallel through a first switch and connecting to the second differential amplifier in parallel through a second switch, wherein the first switch connects to the second switch in series, and the sensing integrated unit comprising;

at least one first charge maintenance circuit for maintaining the averaged sensing value and transmitting the averaged sensing value to a first end of the second differential amplifier, wherein the at least one first charge maintenance circuit receives the averaged sensing value from the integrator when the first switch is closed according to the control of a first part of the second control signals, and the at least one first charge maintenance circuit transmits the averaged sensing value to the second differential amplifier when the second switch is closed according to the control of a second part of the second control signals; and

a third switch connecting to the at least one first charge maintenance circuit in parallel for controlling the operation of the at least one first charge maintenance circuit; and

a second charge maintenance circuit respectively connecting to the voltage buffer in parallel through a fourth switch and to the second differential amplifier in parallel through a fifth switch, and comprising;

a first capacitor for maintaining the reference value and transmitting the reference value to a second end of the second differential amplifier, wherein the first capacitor receives the reference value from the voltage buffer when the fourth switch is closed according to the control of the first part of the second control signals, and the first capacitor transmits the reference value to the second differential amplifier when the fifth switch is closed according to the control of the second part of the second control signals; and

a sixth switch connecting to the first capacitor in parallel for controlling the operation of the first capacitor according to the control of a third part of the second control signals.

6. The sensing device according to claim 5, wherein the at least one first charge maintenance circuit comprises:

a second capacitor connecting to the third switch in parallel for maintaining the averaged sensing value and transmitting the averaged sensing value to the second differential amplifier; and

a seventh switch connecting to the second capacitor in series for controlling the operation of the second capacitor.

7. The sensing device according to claim 6, wherein the third switch is controlled by a fourth part of the second control signals, and the seventh switch is controlled by the selection control signal.

8. The sensing device according to claim 5, wherein the first charge maintenance circuit comprises a second capacitor, the third switch is controlled by a reset signal, wherein the reset signal is used to reset the sensing device.

9. A touch sensing system, comprising:

a touch input interface comprising N signal generation circuits for providing N touch signals to the selector, wherein N is a positive integer;

a sensing device connecting to the touch input interface in series and comprising;

a selector for selecting an ith touch signal and an (i+1)th touch signal from the touch signals according to at least one selection control signal, i is a positive integer from 1 to (N−

1);

a sensing module connecting to the selector in series and comprising a first differential amplifier to compare the selected touch signals and produce a first differential signal according to a plurality of first control signals; and

a detection module connecting to the sensing module in series for according to a plurality of second control signals, generating an averaged sensing value and a reference value from the first differential signal and comparing the averaged sensing value and the reference value to produce a second differential signal; and

a control module connecting to the detection module in series for according to the second differential signal, generating the first control signals and the second control signals;

wherein an ith signal generation circuit of the N signal generation circuits and an (i+1)th sense capacitance circuit of N sense capacitance circuits are selected by the selector and operate synchronously according to a first part and a second part of the first control signals, an ith sense capacitance circuit providing the ith touch signal is adjacent to the (i+1)th sense capacitance circuit providing the (i+1)th touch signal;

wherein the ith sense capacitance circuit and the (i+1)th sense capacitance circuit respectively comprising;

a capacitor; and

a first switch connecting to the capacitor in parallel for controlling the operation of the capacitor;

wherein the ith sense capacitance circuit connects to the (i+1)th sense capacitance circuit in parallel through two second switches which connect to each other in series, the second switches operate synchronously and are controlled by the first part of the first control signals, and the first switches are controlled by the second part of the first control signals.

10. The touch sensing system according to claim 9, wherein the selector is a multiplexer.

11. The touch sensing system according to claim 9, wherein the sensing module further comprises:

a differential amplifier for receiving the ith touch signal and the (i+1)th touch signal to generate the first differential signal;

a first sensing line connecting to a first end of the differential amplifier and comprising a first charge maintenance circuit which connects to the ith sense capacitance circuit through a third switch for receiving the ith touch signal from the ith sense capacitance circuit and transmitting the ith touch signal to the first differential amplifier, wherein the first charge maintenance circuit receives the ith touch signal when the first switch is closed according to the control of a third part of the first control signals; and

a second sensing line connecting to a second end of the differential amplifier and comprising a fourth switch and a second charge maintenance circuit for receiving the (i+1)th touch signal from the (i+1)th sense capacitance circuit and transmitting the (i+1)th touch signal to the differential amplifier, wherein the second charge maintenance circuit receives the (i+1)th touch signal when the fourth switch is closed according to the control of the third part of the first control signals.

12. The touch sensing system according to claim 11, wherein the first charge maintenance circuit and the second charge maintenance circuit respectively comprises a capacitor and a fifth switch which connects to the capacitor in parallel, the fifth switches synchronously operate according to the control of the second part of the first control signals.

13. The touch sensing system according to claim 9, wherein the control module comprising:

a differential amplifier for compensating the second differential signal to generate a third differential signal through a reference voltage;

an analog to digital converter for converting the third differential signal to a digital signal; and

a timing controller for generating the first control signals and the second control signals according to the digital signal and a clock signal.

14. The touch sensing system according to claim 9, wherein the detection module comprising:

an integrator connecting to the sensing module for integrating the first differential signal to generate the averaged sensing value;

a voltage buffer connecting to the integrator in parallel for amplifying the first differential signal to generate the reference value which has a similar order as the averaged sensing value; and

a differential amplifier for simultaneously receiving the averaged sensing value and the reference value to generate the second differential signal, wherein the integrator and the voltage buffer synchronously operate.

15. The touch sensing system according to claim 14, wherein the detection module further comprising:

a sensing integrated unit respectively connecting to the integrator in parallel through a first switch and with the differential amplifier in parallel through a second switch, wherein the sensing integrated unit receives the averaged sensing value when the first switch is closed according to a first part of the second control signals, the sensing integrated unit transmits the averaged sensing value to the differential amplifier when the second switch is closed according to the control of a second part of the second control signals, and the sensing integrated unit comprising;

at least one first charge maintenance circuit for maintaining the averaged sensing value and transmitting the averaged sensing value to a first end of the differential amplifier; and

a third switch connecting to the at least one first charge maintenance circuit in parallel for controlling the operation of the at least one first charge maintenance circuit; and

a second charge maintenance circuit respectively connecting to the voltage buffet in parallel through a fourth switch and to the differential amplifier in parallel through a fifth switch, and comprising;

a first capacitor for maintaining the reference value and transmitting the reference value to a second end of the differential amplifier, wherein the first capacitor receives the reference value when the fourth switch is closed according to the control of the first part of the second control signals, and the first capacitor transmits the reference value to the second end of the differential amplifier when the fifth switch is closed according to the control of the second part of the second control signals; and

a sixth switch connecting to the first capacitor in parallel for controlling the operation of the first capacitor according to the control of a third part of the second control signals.

16. The touch sensing system according to claim 15, wherein the at least one first charge maintenance circuit comprising:

a second capacitor connecting to the third switch in parallel for maintaining the averaged sensing value and transmitting the averaged sensing value to the first end of the differential amplifier; and

a seventh switch connecting to the second capacitor in series for controlling the operation of the second capacitor.

17. The touch sensing system according to claim 16, wherein the third switch is controlled by a fourth part of the second control signals, and the seventh switch is controlled by the selection control signal.

18. The touch sensing system according to claim 15, wherein the first charge maintenance circuit comprises a second capacitor, the third switch is controlled by a reset signal provided by the touch sensing system, wherein the reset signal is used to reset the touch sensing system.

19. A display device comprises the touch sensing system as claimed in claim 9.