Method and apparatus for sensing an input object relative to a sensing region of an ultrasound sensor device

• US 8,711,128 B2
• Filed: 11/04/2011
• Issued: 04/29/2014
• Est. Priority Date: 11/05/2010
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Small, Jeffrey A., Washburn, Clyde
• Primary Examiner(s): Tzeng, Fred
• Application Number:
  US13/289,732
• Publication Number:
  US 20120111119A1
• Time in Patent Office: 907 Days
• Field of Search: 345/177, 345/173, 345/156, 345/168, 345/178, 345/179
• US Class Current: 345/177
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0436 in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate

Abstract

A subsystem, system and method for sensing an input object relative to a sensing region of an ultrasound sensor device are disclosed herein. In one embodiment, a subsystem for sensing an input object relative to a sensing region of an ultrasound sensor device includes a circuit, a switch coupled to an output of the circuit, and an integrating capacitor coupled to the output of the circuit. The circuit has an input for receiving a resulting signal comprising positive and negative polarities, the resulting signal having effects indicative of the input object relative to the sensing region. The integrating capacitor is also coupled to a substantially constant voltage source and to the switch. The circuit is operable to output a rectified signal to the first integrating capacitor indicative of the input object relative to a sensing region.

Claims

1. A subsystem for sensing an input object relative to a sensing region of an ultrasound sensor device, comprising:

a first circuit having an input for receiving a first resulting signal, wherein the first resulting signal is in a form of a waveform comprising positive and negative polarities, the first resulting signal comprising effects indicative of the input object relative to the sensing region;

a first switch coupled to an output of the first circuit; and

a first integrating capacitor coupled to the output of the first circuit, to a substantially constant voltage source and to the first switch, wherein the first circuit is operable to output a first rectified signal to the first integrating capacitor.

2. The subsystem of claim 1 wherein the first rectified signal is based on at least one of the positive polarities and the negative polarities.

3. The subsystem of claim 1 wherein the first rectified signal is based on the positive polarities and the negative polarities.

4. The subsystem of claim 1, wherein the first circuit comprises:

a first transistor network;

a second transistor network operable with the first transistor network to provide a first portion of the first rectified signal to the first integrating capacitor based on the positive polarities; and

a third transistor network operable with the first transistor network to provide a second portion of the first rectified signal to the first integrating capacitor based on the negative polarities, the first portion of the first rectified signal and the second portion of the first rectified signal having the same polarity.

5. The subsystem of claim 4, wherein the first circuit is operable to:

turn on the second transistor network in response to a first timing signal; and

turn on the third transistor network in response to a second timing signal.

6. The subsystem of claim 4 further comprising:

a second circuit having an input for receiving a second resulting signal comprising positive and negative polarities, the second resulting signal comprising effects indicative of the input object relative to the sensing region; and

a second integrating capacitor coupled to the output of the second circuit, wherein the circuit is operable to output a rectified signal to the second integrating capacitor.

7. The subsystem of claim 1, wherein the first circuit, the switch, and the first integrating capacitor are formed by an integrated circuit.

8. A system for sensing an input object relative to a sensing region of an ultrasound sensor device, comprising:

a substrate;

an array of sensor electrodes disposed on the substrate and operable to provide a first resulting signal, wherein the first resulting signal is in a form of a waveform comprising positive and negative polarities in response to presence of the input object in the sensing region; and

a detection module having a first input coupled to the array of sensor electrodes and an output, the detection module operable to integrate charge onto a first integrating capacitor of the detection module with a first rectified signal in response to receiving the first resulting signal.

9. The system of claim 8 wherein the detection module is further operable to integrate charge onto the integrating capacitor in response to at least one of the positive and the negative polarities of the first resulting signal.

10. The system of claim 8 further comprising:

a timing module operable to synchronize a transmitter signal driven onto the array of sensor electrodes and a first and second timing signals provided to the detection module.

11. The system of claim 10 further comprising:

a transmitter module configured to drive the transmitter signal onto the array of sensor electrodes.

12. The system of claim 8 wherein integrating charge onto an integrating capacitor of the detection module with a rectified signal in response to receiving the resulting signal comprises:

integrating charge onto the capacitor in response to the positive polarities of the first resulting signal; and

integrating charge onto the capacitor in the response to negative polarities of the first resulting signal.

13. The system of claim 8, wherein array of sensor electrodes comprises:

a piezoelectric transducer array having a plurality of pixel electrodes coupled to the input of the detection module, a first pixel electrode of the plurality of pixel electrodes configured to provide the first resulting signal.

14. The system of claim 8, wherein the detection module further comprises:

a second input configured to receive a second resulting signal from the array of sensor electrodes, the detection module operable to integrate charge onto a second integrating capacitor of the detection module with a second rectified signal in response to receiving the second resulting signal.

15. The system of claim 8, wherein the array of sensor electrodes are further operable to provide a second resulting signal comprising positive and negative polarities in response to the presence of the input object, and wherein the detection module is further operable to integrate charge onto a second integrating capacitor of the detection module with a second rectified signal in response to receiving the second resulting signal.

16. A method for sensing an input object relative to a sensing region of an ultrasound sensor device, the method comprising:

receiving a first resulting signal, wherein the first resulting signal is in a form of a waveform comprising positive and negative polarities, the first resulting signal comprising effects indicative of the input object relative to the sensing region; and

charging an integrating capacitor with a first rectified signal in response to receiving the first resulting signal.

17. The method of claim 16 further comprising:

driving a transmitter signal onto a plurality of pixel electrodes of a piezoelectric transducer array, a first pixel electrode of the plurality of pixel electrodes providing the first resulting signal.

18. The method of claim 17 further comprising:

generating the first rectified signal in response to a timing signal synchronized with the transmitter signal.

19. The method of claim 16 further comprising:

receiving a second resulting signal comprising positive and negative polarities, the second resulting signal comprising effects indicative of the input object relative to the sensing region, wherein the second resulting signal is received from a second pixel electrode of the plurality of pixel electrodes; and

charging a second integrating capacitor with a second rectified signal in response to receiving the second resulting signal.

20. The method of claim 16, wherein charging the integrating capacitor with the rectified signal further comprising:

integrating charge onto the integrating capacitor in response to at least one of the positive and the negative polarities of the first resulting signal.