Common electrode auto-compensation method

• US 10,146,359 B2
• Filed: 04/01/2016
• Issued: 12/04/2018
• Est. Priority Date: 04/28/2015
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Tang, Howard, Krah, Christoph H., Sacchetto, Paolo, Wang, Chaohao
• Primary Examiner(s): Edwards, Mark
• Application Number:
  US15/089,432
• Publication Number:
  US 20160320898A1
• Time in Patent Office: 977 Days
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• 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 3/04184 Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G09G 2310/0291 Details of output amplifiers or buffers arranged for use in a driving circuit
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
• CPC Class Codes: G09G 3/3677 suitable for active matrices only

Abstract

A system is disclosed. The system can comprise dynamic drive circuitry configured to drive a plurality of electrodes on a touch screen. The system can also comprise a switching circuit configured to selectively couple the dynamic drive circuitry to one or more of the plurality of electrodes. The system can also comprise a display circuitry configured to selectively update a plurality of display pixels on the touch screen. The dynamic drive circuitry can be configured to set its output based on which of the plurality of electrodes are selectively coupled to the first drive circuitry and which of the display pixels are updated by the display circuitry.

Claims

1. A switching circuit comprising:

a first drive circuitry having an output line and configured to output, on the output line, an adjustable output signal, the first drive circuitry configured to drive, via the output line, one or more common electrodes of a plurality of common electrodes of a display, the display including a plurality of display pixels, each of the plurality of display pixels associated with one of the plurality of common electrodes; and

logic configured to;

in accordance with a determination that a first display pixel of the plurality of display pixels is being updated by display circuitry, selectively couple a first set of common electrodes of the plurality of common electrodes to the output line of the first drive circuitry, wherein the first set of common electrodes includes a first common electrode associated with the first display pixel; and

set the adjustable output signal of the first drive circuitry as a function of;

a number of common electrodes in the first set of common electrodes, and

a location of the first display pixel on the display.

2. The switching circuit of claim 1, wherein:

the first drive circuity further includes an input line; and

the logic is further configured to;

selectively couple a second set of common electrodes of the plurality of common electrodes to the input line of the first drive circuitry concurrent with coupling the first set of common electrodes of the plurality of common electrodes to the output line of the first drive circuitry; and

set the adjustable output signal of the first drive circuitry as a function of a number of common electrodes in the second set of common electrodes.

3. The switching circuit of claim 1, wherein:

setting the adjustable output signal of the first drive circuitry includes changing a slew rate of the first drive circuitry.

4. The switching circuit of claim 1, wherein:

the first drive circuitry includes;

an operational amplifier having an input terminal and an output terminal, the output terminal coupled to the output line of the first drive circuitry, and

the logic is further configured to set a gain bandwidth of the operational amplifier as a function of a number of common electrodes in the first set of common electrodes.

5. The switching circuit of claim 4, wherein, the gain bandwidth of the operational amplifier is set by setting a bias current of the operational amplifier.

6. The switching circuit of claim 1, wherein:

setting the adjustable output signal of the first drive circuitry includes changing a gain of the first drive circuitry.

7. The switching circuit of claim 6, wherein:

the first drive circuitry includes;

an operational amplifier having an input terminal and an output terminal, the output terminal coupled to the output line of the first drive circuitry, and

an adjustable capacitor having a feedback capacitance connected between the output terminal and the input terminal; and

the logic is further configured to set the adjustable output signal of the first drive circuitry by adjusting the feedback capacitance.

8. The switching circuit of claim 6, wherein:

the first drive circuitry includes;

an operational amplifier having an input terminal and an output terminal, the output terminal coupled to the output line of the first drive circuitry, and

an adjustable feedback resistor having a feedback resistance connected between the output terminal and the input terminal; and

the logic is further configured to set the adjustable output signal of the first drive circuitry by adjusting the feedback resistance.

9. The switching circuit of claim 6, wherein:

the first drive circuitry includes;

an operational amplifier having an input terminal and an output terminal, the output terminal coupled to the output line of the first drive circuitry, and

an adjustable input resistor having an input resistance connected in series with the input terminal; and

the logic is further configured to set the adjustable output signal of the first drive circuitry by adjusting the input resistance.

10. The switching circuit of claim 1, wherein:

the first set of common electrodes further includes a second common electrode; and

the logic is further configured to;

set the adjustable output signal of the first drive circuitry to have a first value when the first common electrode is coupled to the first drive circuitry;

set the adjustable output signal of the first drive circuitry to have a second value, different from the first value, when the second common electrode is coupled to the first drive circuitry.

11. The switching circuit of claim 1, wherein:

the first set of common electrodes further includes a second common electrode associated with a second display pixel; and

the logic is further configured to, while the first set of common electrodes remains coupled to the output line of the first drive circuitry;

set the adjustable output signal of the first drive circuitry to have a first value when the first display pixel is being updated by display circuitry; and

set the adjustable output signal of the first drive circuitry to have a second value, different from the first value, when the second display pixel is being updated by the display circuitry.

12. The switching circuit of claim 1, wherein the logic is further configured to:

in accordance with a determination that the first display pixel of the plurality of display pixels is being updated for a first time by the display circuitry, set the adjustable output signal of the first drive circuitry to have a first value; and

in accordance with a determination that the first display pixel of the plurality of display pixels is being updated for a second time, after the first time, by the display circuitry, set the adjustable output signal of the first drive circuitry to have a second value, different from the first value.

13. The switching circuit of claim 1, wherein:

the display comprises part of a touch screen, the touch screen configured to operate in a touch sensing phase and a display phase, and

the logic is configured to set the adjustable output signal of the first drive circuitry during the touch sensing phase.

14. The switching circuit of claim 1, wherein:

the display comprises part of a touch screen, and the touch screen comprises a pixelated self-capacitance touch sensor panel, and

the first common electrode comprises a pixelated self-capacitance common electrode.

15. The switching circuit of claim 1, wherein:

the first drive circuitry and the logic are each formed on a same integrated circuit (IC).

16. The switching circuit of claim 1, further comprising:

a second drive circuitry having a second output line different from the output line and configured to output, on the second output line, a second adjustable output signal different from the adjustable output signal, the second drive circuitry configured to drive one or more common electrodes of a second plurality of common electrodes of the display, the display including a second plurality of display pixels, each of the second plurality of display pixels is associated with one of the second plurality of common electrodes;

wherein the logic is further configured to;

in accordance with a determination that a second display pixel of the second plurality of display pixels is being updated by display circuitry, selectively couple a second set of common electrodes of the second plurality of common electrodes to the second output line of the second drive circuitry, wherein the second set of common electrodes of the second plurality of common electrodes includes a second common electrode associated with the second display pixel; and

set the second adjustable output signal of the second drive circuitry as a function of;

a number of common electrodes in the second set of common electrodes, and

a location of the second display pixel on the display.

17. A method comprising:

selectively coupling a first set of common electrodes of a plurality of common electrodes of a display to an output line of a first drive circuitry configured to output, on the output line an adjustable output signal, wherein the first set of common electrodes includes a first common electrode;

while the first set of common electrodes is selectively coupled to the output line of the first drive circuitry, updating a first display pixel of a plurality of display pixels of the display using display circuitry, wherein the first display pixel is associated with the first common electrode; and

in accordance with a determination that the display circuitry is updating the first display pixel of the plurality of display pixels, setting the adjustable output signal of the first drive circuitry as a function of;

a number of electrodes in the first set of common electrodes, and

a location of the first display pixel on the display.

18. The method of claim 17, further comprising:

selectively coupling a second set of common electrodes of the plurality of common electrodes to an input of the first drive circuitry concurrent with selectively coupling the first set of common electrodes to the output line of the first drive circuitry,

wherein setting the adjustable output signal of the first drive circuitry is further a function of a number of common electrodes in the second set of common electrodes.

19. The method of claim 17, wherein:

setting the adjustable output signal of the first drive circuitry includes changing a slew rate of the first drive circuitry.

20. The method of claim 17, wherein:

setting the adjustable output signal of the first drive circuitry includes changing a gain of the first drive circuitry.

21. The method of claim 20, wherein the first drive circuitry includes an operational amplifier having an input terminal and an output terminal, the output terminal coupled to the output line of the first drive circuitry, and an adjustable feedback resistor connected between the output terminal and the input terminal, and wherein:

changing the gain of the first drive circuitry includes changing a value of the adjustable feedback resistor.

22. The method of claim 20, wherein the first drive circuitry includes an operational amplifier having an input terminal and an output terminal, and an adjustable input resistor is connected in series with the input terminal, and wherein:

changing the gain of the first drive circuitry includes changing a value of the adjustable input resistor.

23. The method of claim 17, further comprising:

while the first set of common electrodes is selectively coupled to the output line of the first drive circuitry, updating the first display pixel for a first time;

in accordance with a determination that the display circuitry is updating the first display pixel for the first time, setting the adjustable output signal of the first drive circuitry to have a first value;

subsequent to updating the first display pixel for the first time, selectively coupling a second common electrode to the first drive circuitry output line;

while the first set of common electrodes and the second common electrode are coupled to the first drive circuitry output line, updating the first display pixel for a second time; and

in accordance with a determination that the display circuitry is updating the first display pixel for the second time, setting the adjustable output signal of the first drive circuitry to have a second value, different from the first value.