Resistive scanning grid touch panel

• US 20050275634A1
• Filed: 06/15/2004
• Published: 12/15/2005
• Est. Priority Date: 06/15/2004
• Status: Active Grant

• Current Assignee: Toshiba Global Commerce Solutions Holdings Corporation (Toshiba Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Crockett, Timothy W., Makley, Albert V., Chi, Hye S.
• Granted Patent: US 7,492,358 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

An improved resistive touch panel is disclosed. The improved resistive touch panel includes a first plurality of stripes of a resistive coating on a front sheet running in a first direction and a second plurality of stripes of a resistive coating on a back sheet running in a second direction. The overlapping regions between the first and second plurality of stripes are scanned by a controller circuit to detect voltage drops at these regions. Because the overlapping regions are independent of each other, the controller circuit is able to detect the individual regions involved in the touch area. In this manner, the controller circuit is able to determine between small and large areas of contact by detecting adjacent contact areas.

Claims

1. A resistive touch panel, comprising:

a first sheet, comprising a plurality of stripes of a first resistive coating;

a second sheet, comprising a second resistive coating, wherein a voltage difference exists between the second resistive coating and the plurality of stripes, wherein the plurality of stripes and the second resistive coating form a plurality of independent overlapping regions; and

a controller, wherein the controller detects a contact between the first sheet and the second sheet in at least one of the plurality of independent overlapping regions and scans the plurality of stripes and the second resistive coating to determine a position of the contact.

2. The panel of claim 1, wherein the second resistive coating comprises a second plurality of stripes of the second resistive coating.

3. The panel of claim 2, wherein the plurality of stripes of the first resistive coating runs in a first orientation, wherein the second plurality of stripes run in a second orientation different from the first orientation.

4. The panel of claim 3, wherein the second orientation is approximately perpendicular to the first orientation.

5. The panel of claim 1, wherein the controller comprises:

a microcontroller;

a plurality of analog-to-digital converters coupled to the microcontroller; and

a plurality of multiplexers coupled to the plurality of analog-to-digital converters.

6. The panel of claim 1, wherein the scanning by the controller comprises:

switching between applying a current to each of the plurality of stripes and monitoring the second sheet and applying the current to the second sheet and monitoring each of the plurality of stripes;

determining the position of the contact in a first direction by measuring a first voltage difference between a first and a second side of each of the plurality of stripes, when the current is applied to the first sheet; and

determining the position of the contact in a second direction by measuring a second voltage different between a first and a second side of the second sheet, when the current is applied to the second sheet.

10. The panel of claim 1, wherein the controller comprises:

a microcontroller;

a plurality of analog-to-digital converters coupled to the microcontroller; and

a plurality of multiplexers coupled to the plurality of analog-to-digital converters.

11. The panel of claim 1, wherein the scanning by the controller comprises:

switching between applying a current to each of the first plurality of stripes and monitoring the second plurality of stripes and applying the current to each of the second plurality of stripes and monitoring the first plurality of stripes;

determining the position of the contact in a first direction by measuring a first voltage difference between a first and a second side of each of the first plurality of stripes, when the current is applied to each of the first plurality of stripes; and

determining the position of the contact in a second direction by measuring a second voltage difference between a first and a second side of each of the second plurality of stripes, when the current is applied to each of the second plurality of stripes.

7. A resistive touch panel, comprising:

a first sheet, comprising a first plurality of stripes of a first resistive coating;

a second sheet, comprising a second plurality of stripes of a second resistive coating, wherein a voltage different exists between the first plurality of strips and the second plurality of strips, wherein the first and second plurality of stripes form a plurality of independent overlapping regions; and

a controller, wherein the controller detects a contact between the first and second plurality of stripes and scans the first and second plurality of stripes to determine a position of the contact.

8. The panel of claim 7, wherein the first plurality of stripes runs in a first orientation, wherein the second plurality of stripes run in a second orientation different from the first orientation.

9. The panel of claim 8, wherein the second orientation is approximately perpendicular to the first orientation.