Low power dissipation touch plane interface circuit

• US 6,753,853 B1
• Filed: 09/29/2000
• Issued: 06/22/2004
• Est. Priority Date: 09/29/2000
• Status: Expired due to Term

• Current Assignee: Display Vectors LLC (Jeffrey M. Gross)
• Original Assignee: Rockwell Automation Technologies Incorporated (Rockwell Automation, Inc.)
• Inventors: Dotson, Gary Dan
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): NGUYEN, FRANCIS N
• Application Number:
  US09/677,103
• Time in Patent Office: 1,362 Days
• Field of Search: 345/173-174, 315/7, 361/681, 361/683, 382/189, 382/315, 178/18.01, 178/18-3-, 178/20.03, 710/46, 710/15, 708/131, 708/138, 341/20, 341/22, 341/33.34
• US Class Current: 345/173
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/325 Power saving in peripheral device
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

A method of determining a type of touch plane operator input device comprises sensing the impedance across first and second terminals of a touch plane operator input device to distinguish the touch plane operator input device as being one of at least two different types of touch plane operator input devices. A method of processing an input from a touch plane operator input device comprises determining a first location of a first touch on the touch plane operator input device; determining a second location of a second touch on the touch plane operator input device; comparing the first and second locations to obtain an indication of an amount of difference between the first and second locations; and determining whether the indication of the amount of difference exceeds a predetermined amount. These steps are performed by discrete logic circuitry that provides an event notification to a microprocessor when the indication of the amount of difference exceeds the predetermined amount. An interface circuit for a touch plane operator input device comprises a digital signal processor that includes a data processing path along which data from a touch plane operator input device passes while being processed by the digital signal processor. The interface circuit is capable of processing data from first and second different types of touch plane operator input devices. The data path is a common data processing path that is the same for input data for both of the first and second types of touch plane operator input devices.

Claims

1. A method of acquiring an operator input from a touch plane operator input device having first and second touch-sensitive layers, comprising:

placing a touch plane interface circuit into a scanning configuration, the scanning configuration being a configuration in which the interface circuit applies a scanning signal to first and second terminals of the first layer of the touch plane operator input device, the scanning configuration causing a current to flow through the first and second terminals;

placing the touch plane interface circuit into a touch detect configuration, the touch detect configuration being a configuration in which the first layer is substantially free of current flow between the first and second terminals as compared to the current that flows when the touch plane interface is in the scanning configuration, such that substantially no power is dissipated by the first layer during the scanning step as compared to the power that is dissipated when the touch plane interface is in the scanning configuration;

waiting for an operator touch to occur on the touch plane operator input device;

detecting that the operator touch has occurred; and

issuing an event notification to notify a microprocessor of the operator touch; and

wherein the first and second layers are substantially free of current flow during the waiting step.

2. A method according to claim 1,

wherein the touch plane operator input device is either a 4-wire touch plane operator input device or an 8-wire touch plane operator input device with the first layer being an X-axis resistive layer and the second layer being a Y-axis resistive layer; and

wherein detecting the operator touch comprises determining that an electrical contact has been made between the X-axis resistive layer and the Y-axis resistive layer; and

wherein the method further comprises determining the location of the operator touch including determining the location of the electrical contact between the X-axis and Y-axis resistive layers.

3. A method according to claim 1,

wherein the touch plane operator input device is either a 5-wire touch plane operator input device or a 7-wire touch plane operator input device with the first layer being a resistive layer and the second layer being a wiper layer;

wherein detecting the operator touch comprises determining that an electrical contact has been made between the resistive layer and the wiper layer; and

wherein the method further comprises determining the location of the operator touch including determining the location of the electrical contact between resistive layer and the wiper layer.

4. A method according to claim 1, wherein the event notification comprises an interrupt signal.

5. A method according to claim 1, wherein the event notification comprises a hardware interrupt signal.

6. A method according to claim 1, wherein waiting for the operator touch, detecting that the operator touch has occurred, and issuing the event notification are performed by a logic circuit which is coupled to the microprocessor.

7. A method of acquiring an operator input from a touch plane operator input device having first and second layers, comprising:

placing a touch plane interface circuit into a scanning configuration, the scanning configuration being a configuration in which the interface circuit applies a scanning signal to first and second terminals of the first layer of the touch plane operator input device, the scanning configuration causing a current to flow through the first and second terminals;

determining a location of a first operator touch by determining a location of the electrical contact between the first and second layers caused by the first operator touch;

placing the touch plane interface circuit into a touch detect configuration, the touch detect configuration being a configuration in which the first layer is substantially free of current flow between the first and second terminals as compared to the current that flows when the touch plane interface is in the scanning configuration, such that substantially no power is dissipated by the first layer during the scanning step as compared to the power that is dissipated when the touch plane interface is in the scanning configuration; and

waiting for a second operator touch to occur on the touch plane operator input device while the touch plane interface circuit is in the touch detect configuration.

8. A method according to claim 7, wherein the step of placing the touch plane interface into the scanning configuration comprises placing an analog switch matrix into a scanning configuration, and wherein the step of placing the touch plane interface into the touch detect configuration comprises placing an analog switch matrix into a touch detect configuration.

9. A method according to claim 7, wherein the touch plane operator interface in combination with the display forms an analog resistive touch screen.

10. A method according to claim 7, wherein the touch plane operator interface is an analog resistive touch pad.

11. A method according to claim 7, further comprising

detecting that the second operator touch has occurred; and

issuing an event notification to a microprocessor to notify the microprocessor of the second operator touch.

12. A method according to claim 11, wherein the event notification comprises an interrupt signal.

13. A device comprising:

(A) a display;

(B) a touch plane operator input device, the touch plane operator input device including a touch plane sensor system having first and second layers; and

(C) an integrated circuit, the integrated circuit including

(1) an analog switch matrix, the analog switch matrix having a plurality of analog switches and having a plurality of different configurations defined by on/off states of the plurality of analog switches,

(2) an analog-to-digital converter, the analog-to-digital converter being coupled to receive the input data from the analog switch matrix, and

(3) a digital signal processor, the digital signal processor being capable of determining the location of an operator touch on the touch plane operator input device based on input data received by the digital signal processor from the analog-to-digital converter;

wherein the plurality of configurations of the analog switch matrix include a scanning configuration in which current flows to at least one of the first and second layers from the analog switch matrix; and

wherein the plurality of configurations of the analog switch matrix include a touch detect configuration in which substantially no current flows to the first and second layers from the analog switch matrix as compared to the current that flows while the analog switch matrix is in the scanning configuration, such that substantially no power is dissipated by the first and second layers as compared to the power that is dissipated while the analog switch matrix is in the scanning configuration.

14. A device according to claim 13, wherein the touch plane operator input device is either a 4-wire touch plane operator input device or an 8-wire touch plane operator input device.

15. A device according to claim 13, wherein the touch plane operator input device is either a 5-wire touch plane operator input device or a 7-wire touch plane operator input device.

16. A device comprising:

(A) a display;

(B) a touch plane operator input device, the touch plane operator input device including a touch plane sensor system having first and second layers; and

(C) an integrated circuit, the integrated circuit including

(1)an analog switch matrix, the analog switch matrix having a plurality of analog switches and having a plurality of different configurations defined by on/off states of the plurality of analog switches,

(2) an analog-to-digital converter, the analog-to-digital converter being coupled to receive the input data from the analog switch matrix, and

(3) a digital signal processor, the digital signal processor being capable of determining the location of an operator touch on the touch plane operator input device based on input data received by the digital signal processor from the analog-to-digital converter, the digital signal processor further comprising a microprocessor and a logic circuit, wherein the logic circuit is configured to detect that the operator touch has occurred and issue an event notification to the microprocessor to notify the microprocessor of the operator touch;

wherein the plurality of configurations of the analog switch matrix include a scanning configuration in which current flows to at least one of the first and second layers from the analog switch matrix; and

wherein the plurality of configurations of the analog switch matrix include a touch detect configuration in which substantially no current flows to the first and second layers from the analog switch matrix as compared to the current that flows while the analog switch matrix is in the scanning configuration, such that substantially no power is dissipated by the first and second layers as compared to the power that is dissipated while the analog switch matrix is in the scanning configuration.

17. A device according to claim 16, wherein the device is a personal digital assistant.

18. A device according to claim 16, wherein the device is a portable Internet access device.

19. A device according to claim 16, wherein the device is a laptop computer, and the touch plane is a mouse control device for the laptop computer.