Method and apparatus for improved input sensing using a display processor reference signal

• US 10,095,356 B2
• Filed: 11/15/2016
• Issued: 10/09/2018
• Est. Priority Date: 08/31/2012
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Schwartz, Adam, Reynolds, Joseph Kurth
• Primary Examiner(s): Cheng, Joe H
• Application Number:
  US15/352,181
• Publication Number:
  US 20170060344A1
• Time in Patent Office: 693 Days
• CPC Class Codes: G06F 2203/04108 Touchless 2D- digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface without distance measurement in the Z direction
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• 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

Abstract

Embodiments of the invention generally provide a method and apparatus that is configured to reduce the effects of interference that is undesirably provided to a transmitter signal that is delivered from a transmitter signal generating device to a sensor processor to determine if an input object is disposed within a touch sensing region of a touch sensing device. In one embodiment, the sensor processor includes a receiver channel that has circuitry that is configured to separately receive a transmitter signal delivered from a display processor and a sensor processor reference signal that is based on a display processor reference signal to reliably sense the presence of an object. Embodiments of the invention described herein thus provide an improved apparatus and method for reliably sensing the presence of an object by a touch sensing device.

Claims

1. An input device, comprising:

a plurality of transmitter electrodes comprising common electrodes, wherein each of the common electrodes are configured to be driven for display updating in a first mode and capacitive sensing in a second mode;

a plurality of receiver electrodes;

a display processor configured to drive at least one transmitter electrode of the plurality of transmitter electrodes with a transmitter signal for capacitive sensing in the second mode; and

a sensor processor configured to receive resulting signals with the plurality of receiver electrodes when the at least one transmitter electrode is driven in the second mode, wherein the sensor processor comprises;

one or more receiver channels, and wherein each of the one or more receiver channels is configured to be coupled to at least one receiver electrode of the plurality of receiver electrodes, wherein each of the one or more receiver channels is configured to provide an output signal based on a comparison of at least a portion of the resulting signals and a sensor processor reference signal that is based on a display processor reference signal.

2. The input device of claim 1, wherein the sensor processor further comprises:

a first reference channel configured to provide a first reference channel output signal based on a first reference channel input signal, wherein the first reference channel input signal is based on the transmitter signal.

3. The input device of claim 2, wherein the sensor processor further comprises:

a second reference channel configured to provide a second reference channel output signal based on a second reference channel input signal, wherein the second reference channel input signal is based on the transmitter signal.

4. The input device of claim 1, wherein the one or more receiver channels comprise:

an input port configured to receive a sensor processor reference signal that is based on the display processor reference signal.

5. The input device of claim 4, wherein the display processor reference signal is configured to be electrically coupled to a ground of the sensor processor.

6. The input device of claim 1, wherein the one or more receiver channels further comprises:

a charge accumulator.

7. The input device of claim 6, wherein the charge accumulator comprises:

an integrator-type operational amplifier.

8. The input device of claim 1 further comprising:

a capacitive element coupled to a first reference channel input port of a reference channel, and wherein the capacitive element is configured to have the transmitter signal driven onto the capacitive element.

9. A sensor processor for an input device, comprising:

sensor processor circuitry configured to receive resulting signals with a plurality of receiver electrodes, the received resulting signals comprising effects of a transmitter signal driven on at least one transmitter electrode of a plurality of transmitter electrodes that comprise common electrodes, wherein the sensor processor circuitry comprises;

one or more receiver channels, and wherein each of the one or more receiver channels is configured to be coupled to at least one receiver electrode of the plurality of receiver electrodes, wherein each of the one or more receiver channels is configured to provide an output signal based on a comparison of at least a portion of the resulting signals and a sensor processor reference signal that is based on a display processor reference signal.

10. The sensor processor of claim 9, wherein the display processor reference signal is configured to be electrically coupled to a ground of the sensor processor.

11. The sensor processor of claim 9 further comprising:

a first reference channel configured to be capacitively coupled to the transmitter signal, the first reference channel configured to provide a first reference channel output signal.

12. The sensor processor of claim 11 further comprising:

a second reference channel configured to provide a second reference channel output signal.

13. The sensor processor of claim 9, wherein the one or more receiver channels further comprises:

a first input port configured to receive the resulting signal from at least one receiver electrode, a second input port configured to receive the sensor processor reference signal, and an output port configured to output the output signal.

14. The sensor processor of claim 9 further comprising:

a display processor configured to drive the common electrodes for capacitive sensing with the transmitter signal.

15. The sensor processor of claim 9, wherein the one or more receiver channels further comprises:

a charge accumulator.

16. The sensor processor of claim 15, wherein the charge accumulator comprises:

an integrator-type operational amplifier.

17. The sensor processor of claim 9, wherein the sensor processor circuitry further comprises:

a demodulator circuit.

18. The sensor processor of claim 9 further comprising:

a reference channel configured to provide a reference channel output signal, wherein the reference channel has a first reference channel input port that is configured to receive a reference channel input signal, wherein the reference channel input signal is based on the transmitter signal; and

wherein each of the one or more receiver channels is configured to provide an output signal based on at least a portion of the resulting signals and the reference channel output signal.

19. The sensor processor of claim 9 further comprising:

a display processor configured to drive the at least one transmitter electrode with the transmitter signal for capacitive sensing in a first mode and to drive the common electrodes for display updating during a second mode, the display processor and the sensor processor circuitry residing on a single integrated circuit chip.

20. A processing system for an input device, the processing system comprising:

a display processor configured to drive a plurality of common electrodes for updating a display device, the display processor configured to drive at least one common electrode of the plurality of common electrodes with a transmitter signal for capacitive sensing; and

a sensor processor configured to receive resulting signals with a plurality of receiver electrodes when the at least one common electrode of the plurality of common electrodes is driven with the transmitter signal, wherein the sensor processor comprises;

one or more receiver channels, and wherein each of the one or more receiver channels is configured to be coupled to at least one receiver of the plurality of receiver electrodes, wherein each of the one or more receiver channels is configured to provide an output signal based on a comparison of at least a portion of the resulting signals and a sensor processor reference signal that is based on a display processor reference signal, wherein the one or more receiver channels further comprises;

a first input port configured to receive the resulting signal from at least one receiver electrode;

a second input port configured to receive the sensor processor reference signal; and

an output port configured to output the output signal.