Position-sensing and force detection panel

• US 9,223,445 B2
• Filed: 12/02/2010
• Issued: 12/29/2015
• Est. Priority Date: 12/02/2010
• Status: Active Grant

• Current Assignee: Neodrón Limited (Atlantic IP Services Limited)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Sleeman, Peter, Dubery, John
• Primary Examiner(s): Sharifi-Tafreshi, Koosha
• Assistant Examiner(s): Lin, Chun-Nan
• Application Number:
  US12/959,166
• Publication Number:
  US 20120139864A1
• Time in Patent Office: 1,853 Days
• Field of Search: 345173-184, 178 1802- 1907, 338/68
• US Class Current: 1/1
• CPC Class Codes: G01L 1/14 by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
• CPC Class Codes: G01L 1/205 using distributed sensing elements
• CPC Class Codes: G01L 5/228 using tactile array force sensors
• CPC Class Codes: G06F 2203/04105 Pressure sensors for measuring the pressure or force exerted on the touch surface without providing the touch position
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• CPC Class Codes: G06F 3/044 by capacitive means
• 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

Abstract

Disclosed is a touch position sensor. Force detection circuitry can be included with the position sensor, for example, to determine an amount of force applied to a touch panel of the sensor.

Claims

1. A touch sensor comprising:

a controller comprising a voltage driver and an integrator circuit with an input, the voltage driver providing an alternating voltage;

a plurality of first electrodes formed of a first conductive material and arranged in a first direction in a sensing area, each of the plurality of electrodes in communication with the controller, the plurality of first electrodes configured to be driven by the voltage driver;

a plurality of second electrodes formed of a second conductive material and arranged in a second direction different from the first direction such that the first and second electrodes form capacitive touch sensing nodes in the sensing area, each of the second plurality of electrodes in communication with the controller;

a variable resistance element connected between the voltage driver and the input of the integrator circuit, and configured to change a parameter of the variable resistance element in response to a force applied thereto, wherein the integrator circuit is configured to measure the parameter over a period of time and wherein the variable resistance element is configured to be driven by the voltage driver; and

circuity configured to determine;

an amount of force applied to the sensor in response to the measured parameter; and

a location in the sensing area of an input associated with the force based on one or more changes in capacitance at one or more of the capacitive touch sensing nodes.

2. The touch sensor of claim 1 wherein the parameter is current flowing through the variable resistance element.

3. The touch sensor of claim 1 wherein the variable resistance element comprises a Quantum Tunnel Composite (QTC) material.

4. The touch sensor of claim 1 wherein the variable resistance element comprises a force sensitive resistor.

5. The touch sensor of claim 1 further comprising another variable resistance element in communication with another voltage driver of the controller and the input of the integrator circuit of the controller.

6. The touch sensor of claim 1, wherein the input of the integrator circuit is at a voltage between a first voltage and a second voltage of the alternating voltage provided by the voltage driver.

7. The touch sensor of claim 1, where in the circuitry is further configured to determine an amount of force applied to the sensor using a differential measurement.

8. A touch sensitive device comprising:

a housing;

a controller within the housing, comprising a voltage driver and an integrator circuit with an input, the voltage driver providing an alternating voltage;

a touch sensitive position-sensing panel housed partially within the housing, the touch sensitive position-sensing panel comprising;

a plurality of first electrodes formed of a first conductive material and arranged in a first direction in a sensing area of the panel, each of the plurality of electrodes in communication with the controller, the plurality of first electrodes configured to be driven by the voltage driver; and

a plurality of second electrodes formed of a second conductive material and arranged in a second direction different from the first direction such that the first and second electrodes form capacitive touch sensing nodes in the sensing area, each of the second plurality of electrodes in communication with the controller; and

a variable resistance element connected between the voltage driver and the input of the integrator circuit, and configured to change a parameter of the variable resistance element in response to a force applied thereto wherein the integrator circuit is configured to measure the parameter over a period of time and wherein the variable resistance element is configured to be driven by the voltage driver; and

circuitry configured to determine;

an amount of force applied to the sensing area of the touch sensitive panel in response to the measured parameter; and

a location in the sensing area of an input associated with the force based on one or more changes in capacitance at one or more of the capacitive touch sensing nodes.

9. The touch sensitive device of claim 8 wherein the parameter is current flowing through the variable resistance element.

10. The touch sensitive device of claim 8 wherein the variable resistance element comprises a Quantum Tunnel Composite (QTC) material.

11. The touch sensitive device of claim 8 wherein the variable resistance element comprises a force sensitive resistor.

12. The touch sensitive device of claim 8 further comprising another variable resistance element disposed within the housing in communication with another voltage driver of the controller and the input of the integrator circuit of the controller.

13. The touch sensitive device of claim 8, wherein the input of the integrator circuit is at a voltage between a first voltage and second voltage of the alternating voltage provided by the voltage driver.

14. A force sensor, for a touch sensor, the force sensor comprising:

a variable resistance element in communication with a voltage driver of a controller of the touch sensor, the variable resistance element configured to receive an alternating voltage from the voltage driver;

a bias resistance element connected in parallel with the variable resistance element; and

configured to provide, if a resistance of the variable resistance element rises to a first value, a current path; and

a limiting resistance element connected in series between the variable resistance element and an input of an integrator of the controller, wherein current flowing from the variable resistance element to the input of the integrator passes through the limiting resistance element, the limiting resistance element being configured to limit, if a resistance of the variable resistance element drops to a second value, a maximum current flow through the variable resistance element to the input of the integrator; and

wherein the controller is further in communication with drive electrodes and sense electrodes of a capacitive touch sensitive panel of the touch sensor, the drive electrodes configured to receive the alternating voltage from the voltage driver.

15. The force sensor of claim 14 wherein the variable resistance element comprises a Quantum Tunnel Composite (QTC) material.

16. The force sensor of claim 14 wherein variable resistance element comprises a force sensitive resistor.

17. The force sensor of claim 14 wherein the input of the integrator circuit is at a voltage between a first voltage and a second voltage of the alternating voltage provided by the voltage driver.