Analog to digital converter controller

• US 7,079,117 B2
• Filed: 05/15/2003
• Issued: 07/18/2006
• Est. Priority Date: 05/15/2003
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Vinau, Jose M., Handa, Yukihisa, Kearney, Thomas P., Pratt, Susan M.
• Primary Examiner(s): Shankar, Vijay
• Assistant Examiner(s): DHARIA, PRABODH M
• Application Number:
  US10/439,209
• Publication Number:
  US 20040227735A1
• Time in Patent Office: 1,160 Days
• Field of Search: 345/173, 345/174, 345/179, 178/18, 178/19, 178/20, 178/18.01, 178/18.03, 178/19.01, 340/712, 705/7, 705/22, 702/22, 702/77
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: H03M 1/46 with digital/analogue converter for supplying reference values to converter

Abstract

A touch screen controller has a converter that digitizes analog input as a function of an interference signal generated by an underlying touch screen device. To that end, the touch screen controller includes a set of inputs for receiving the noted interference signal from the touch screen device. The set of inputs also receives analog data from the touch screen device. The above noted converter, which is operatively coupled with the set of inputs, is capable of digitizing the analog data received from the touch screen device as a function of the interference signal.

Claims

1. A touch screen controller for use with a touch screen device, the touch screen controller comprising:

a set of inputs for receiving an interference signal from the touch screen device,

the set of inputs also receiving analog data from the touch screen device; and

a converter operatively coupled with the set of inputs,

the converter having a disable module that monitors the interference signal and enables and disables the converter based upon the timing of the interference signal, the set of inputs receiving the analog data when the converter is disabled, the converter tracking the analog data when disabled, the converter not converting the tracked analog data when disabled.

2. The touch screen controller as defined by claim 1 further including a delay module for preventing the converter from digitizing for a selected delay period after the beginning of the off cycle of the interference signal.

3. The touch screen controller as defined by claim 1 wherein the converter has an acquisition stage for acquiring the analog data, the converter also having a conversion stage for digitizing the acquired analog data, the converter being capable of digitizing given acquired data received during the on cycle of the interference signal, the given acquired data having been acquired during the off cycle of the interference signal.

4. The touch screen controller as defined by claim 1 wherein the converter has a acquisition stage for acquiring the analog data, and a conversion stage for digitizing the acquired analog data, the conversion stage being prevented from digitizing at some time during the on cycle of the interference signal.

5. The touch screen controller as defined by claim 1 wherein the converter has a acquisition stage for acquiring the analog data, and a conversion stage for digitizing the acquired analog data, the acquisition stage is disabled as a function of the interference signal.

6. The touch screen controller as defined by claim 1 wherein the interference signal is capable of distorting the data received from the touch screen device, the interference signal being a display device refresh signal.

7. The touch screen controller as defined by claim 1 wherein the touch screen device includes one of a liquid crystal display device and a cathode ray tube display device.

8. A controller for controlling an analog-to-digital converter, the controller comprising:

an input for receiving an interference signal;

logic operatively coupled with the input, the logic producing a control signal that is a function of the interference signal; and

an output for forwarding the control signal to the analog-to-digital converter, the analog-to-digital converter digitizing analog signals as a function of the control signal;

a converter operatively coupled with the set of inputs the converter having a disable module that monitors the interference signal and enables and disables the converter based upon the timing of interference signal, the set of inputs receiving the analog data when the converter is disabled, the converter tracking the analog data when disabled, the converter not converting the tracked analog data when disabled.

9. The controller as defined by claim 8 wherein the controller includes an internal analog-to-digital converter, the output being coupled with the internal analog-to-digital converter, the control signal controlling the internal analog-to-digital converter.

10. The controller as defined by claim 9 further including means for preventing the internal analog-to-digital converter from digitizing for a selected delay period after the beginning of an off cycle of the interference signal.

11. The controller as defined by claim 9 wherein the internal analog-to-digital converter is a successive approximation register analog-to-digital converter.

12. The controller as defined by claim 9 wherein the interference signal has an on cycle and an off cycle, the control signal preventing the internal analog-to-digital converter from digitizing at some time during the on cycle of the interference signal.

13. A touch screen system comprising:

a display device having at least one touch sensitive sheet that, when driven, generates analog data in response to contact;

a set of inputs for receiving an interference signal from the touch screen device, the set of inputs also receiving the analog data from the touch screen device; and

a converter operatively coupled with the set of inputs, the converter having a disable module that monitors the interference signal and enables and disables the converter based upon the timing of the interference signal, the display device being driven to generate the analog data when the converter is disabled.

14. The touch screen system as defined by claim 13 further including a processing module operatively coupled with the converter, the processing module capable of converting data received from the touch screen controller into position information.

15. The touch screen controller as defined by claim 13 wherein the interference signal has an off cycle and an on cycle, the disable module capable of preventing the converter from digitizing at some time during the on cycle of the interference signal.

16. The touch screen controller as defined by claim 15 wherein the converter has a acquisition stage for acquiring the analog data, and a conversion stage for digitizing the acquired analog data, the conversion stage being prevented from digitizing at some time during the on cycle of the interference signal.

17. The touch screen controller as defined by claim 13 wherein the interference signal is capable of distorting the data received from the display device, the interference signal being a display device refresh signal.

18. The touch screen controller as defined by claim 13 wherein the display device includes one of a liquid crystal display device and a cathode ray tube display device, the display device having resistive sheets to produce a resistive touch display device.