Reduction of noise in touch data samples via sampling during porch time of Vsync and Hsync signals

Patent metadata

Field	Value
Publication number	US-10088965-B2
Application number	US-201615381489-A
Country	US
Kind code	B2
Filing date	Dec 16, 2016
Priority date	Dec 16, 2016
Publication date	Oct 2, 2018
Grant date	Oct 2, 2018

Abstract

Disclosed herein is a touch screen controller for controlling touch sensing in a touch screen display, the touch screen display having a display layer controlled as a function of horizontal sync and vertical sync signals and a capacitive touch array comprised of drive lines and sense lines. The touch screen controller includes a driver and control circuitry. The control circuitry is configured to cause the driver to generate a driving signal on the drive lines during assertion of the horizontal sync signal, and cause the driver to generate the driving signal on the drive lines during assertion of the vertical sync signal. Analog touch sensing circuitry is configured to generate analog touch data as a function of signals on the sense lines resulting from generation of the drive signal on the drive lines.

First claim

The invention claimed is:

1. A touch screen controller for controlling touch sensing in a touch screen display, the touch screen display having a display layer controlled as a function of horizontal sync and vertical sync signals and a capacitive touch array comprised of drive lines and sense lines, the touch screen controller comprising:
a driver;
control circuitry configured to:
cause the driver to generate a driving signal on the drive lines during assertion of the horizontal sync signal, and
cause the driver to generate the driving signal on the drive lines during assertion of the vertical sync signal; and

analog touch sensing circuitry configured to generate analog touch data as a function of signals on the sense lines resulting from generation of the drive signal on the drive lines.

2. The touch screen controller of claim 1 , wherein the control circuitry is configured to generate the driving signal on the drive lines during a period beginning a first wait time after start of assertion of the vertical sync signal and ending at end of assertion of the vertical sync signal; and wherein the control circuitry is configured to generate the driving signal on the drive lines during a period beginning a second wait time after start of assertion of the horizontal sync signal and ending at end of assertion of the horizontal sync signal.

3. The touch screen controller of claim 2 , wherein the first and second wait times are unequal.

4. The touch screen controller of claim 2 , wherein the first wait time is longer than the second wait time.

5. The touch screen controller of claim 1 , further comprising an analog to digital converter configured to convert the analog touch data to digital touch data, and to perform noise reduction on the digital touch data.

6. The touch screen controller of claim 1 , wherein the horizontal sync and vertical sync signals are components of a combined vertical-horizontal sync signal.

7. The touch screen controller of claim 6 , wherein the control circuitry causes the driver to generate the driving signal on the drive lines during assertion of the horizontal sync signal by generating the driving signal on the drive lines a first set number of times during assertion of the vertical-horizontal sync signal; and wherein the control circuitry causes the driver to generate the driving signal on the drive lines during assertion of the vertical sync signal by generating the driving signal on the drive lines a second set number of times based on lack of deassertion of the vertical-horizontal sync signal after generating the driving signal the first set number of times.

8. The touch screen controller of claim 1 , further comprising an OR gate receiving the horizontal and vertical sync signals and generating therefrom a vertical-horizontal sync signal representing a logical OR of the horizontal and vertical sync signals.

9. The touch screen controller of claim 8 , wherein the control circuitry causes the driver to generate the driving signal on the drive lines during assertion of the horizontal sync signal by generating the driving signal on the drive lines a first set number of times during assertion of the vertical-horizontal sync signal; and wherein the control circuitry causes the driver to generate the driving signal on the drive lines during assertion of the vertical sync signal by generating the driving signal on the drive lines a second set number of times based on lack of deassertion of the vertical-horizontal sync signal after generating the driving signal the first set number of times.

10. A touch screen controller for controlling touch sensing in a touch screen display controlled as a function of horizontal sync and vertical sync, the touch screen controller comprising:
a driver;
an OR gate receiving as input the horizontal and vertical sync signals and generating therefrom a vertical-horizontal sync signal as a function of a logical OR of the horizontal and vertical sync signals; and
control circuitry configured to:
cause the driver to generate a touch sensing driving signal a first number of times after detection of assertion of the vertical-horizontal sync signal, and
cause the drive to generate the touch sensing driving signal a second number of times after generation of the touch sense driving signal the first number of times, based on lack of deassertion of the vertical-horizontal sync signal after generation of the touch sense driving signal the first number of times.

11. The touch screen controller of claim 10 , further comprising analog touch sensing circuitry configured to generate analog touch data as a function of signals on sense lines resulting from generation of the drive signal on the drive lines.

12. The touch screen controller of claim 11 , further comprising an analog to digital converter configured to convert the analog touch data to digital touch data, and to perform noise reduction on the digital touch data.

13. The touch screen controller of claim 10 , wherein the control circuitry is configured to generate the touch sensing driving signal during a period beginning a wait time after start of assertion of the vertical-horizontal sync signal and ending at end of deassertion of the vertical-horizontal sync signal.

14. A method, comprising:
generating a driving signal on drive lines of a capacitive touch array during assertion of a horizontal sync signal for a display, and
generating the driving signal on the drive lines during assertion of a vertical sync signal for the display; and
generating analog touch data as a function of signals on sense lines of the capacitive touch array resulting from generation of the driving signal on the drive lines.

15. The method of claim 14 , wherein the driving signal is generated on the drive lines during a period beginning a first wait time after start of assertion of the vertical sync signal and ending at end of assertion of the vertical sync signal; and wherein the driving signal is generated on the drive lines during a period beginning a second wait time after start of assertion of the horizontal sync signal and ending at end of assertion of the horizontal sync signal.

16. The method of claim 15 , wherein the first wait time is longer than the second wait time.

17. The method of claim 14 , further comprising converting the analog touch data to digital touch data, and performing noise reduction on the digital touch data.

18. A method, comprising:
generating a vertical-horizontal sync signal as a function of a logical OR of horizontal and vertical sync signals for a display;
generating a touch sensing driving signal a first number of times after detection of assertion of the vertical-horizontal sync signal;
generating the touch sensing driving signal a second number of times after generation of the touch sense driving signal the first number of times, based on lack of deassertion of the vertical-horizontal sync signal after generation of the touch sense driving signal the first number of times; and
generating analog touch data as a function of signals on sense lines resulting from generation of the touch sensing drive signal.

19. The method of claim 18 , wherein the touch sensing driving signal is generated during a period beginning a wait time after start of assertion of the vertical-horizontal sync signal and ending at end of deassertion of the vertical-horizontal sync signal.

20. The method of claim 18 , further comprising converting the analog touch data to digital touch data, and performing noise reduction on the digital to

Assignees

• St Microelectronics Asia Pacific Pte Ltd

Inventors

• Karuppusamy Baranidharan
• Zhang Chaochao
• Ningrat Kusuma Adi

Classifications

• G06F3/0418 Primary

  for error correction or compensation, e.g. based on parallax, calibration or alignment · CPC title

• G06F3/044 Primary

  by capacitive means · CPC title

• G06F3/04184

  Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally · CPC title

• G06F3/0445 Primary

  using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer · CPC title