INFRARED SENSOR INTEGRATED IN A TOUCH PANEL

• US 20110157094A1
• Filed: 03/11/2011
• Published: 06/30/2011
• Est. Priority Date: 11/27/2006
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Boer, Willem den, Bathiche, Steven N., Izadi, Shahram, Hodges, Stephen Edward
• Granted Patent: US 8,466,902 B2
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06V 40/1318 using electro-optical elements or layers, e.g. electroluminescent sensing

Abstract

An infrared source is configured to illuminate the underside of one or more objects on or above a touchable surface of a touch panel. Infrared light reflected from the underside of the object(s) is detected by an infrared sensor integrated in the touch panel below the touchable surface.

Claims

1. A touch panel system comprising:

a touchable surface;

at least one infrared source integrated in the touch panel system and configured to direct infrared radiation towards and through the touchable surface for illuminating one or more objects that are in contact with or adjacent to the touchable surface with infrared radiation; and

an active matrix circuit comprising;

an infrared sensor that is sensitive to infrared radiation incident on the infrared sensor which is directed by the at least one infrared source towards and through the touchable surface and reflected from above the touchable surface by the one or more objects;

a capacitor interconnected to the infrared sensor; and

a readout transistor interconnected to the infrared sensor and the capacitor, wherein a voltage imposed on the capacitor discharges through the infrared sensor if infrared radiation is incident on the infrared sensor, a charge to reset the voltage on the capacitor flows through the readout transistor, and a measure of the infrared radiation incident on the infrared sensor is output based on the charge needed to reset the voltage on the capacitor.

2. The touch panel system of claim 1, wherein the at least one infrared source is integrated in one of a frontlight and a backlight of the touch panel system.

3. The touch panel system of claim 1, wherein the at least one infrared source comprises an infrared organic light emitting diode emitter.

4. The touch panel system of claim 1, wherein the infrared sensor comprises an infrared-sensitive thin film transistor.

5. The touch panel system of claim 4, wherein a drain and a gate of the infrared-sensitive thin film transistor are interconnected to a common bias line which is interconnected to a plurality of pixel circuits.

6. The touch panel system of claim 4, wherein the infrared-sensitive thin film transistor comprises:

a gate that is reflective to infrared radiation; and

a film that absorbs infrared radiation directed by the at least one infrared source towards and through the touchable surface which is reflected from above the touchable surface by the one or more objects and absorbs infrared radiation which is reflected from below the film by the gate.

7. The touch panel system of claim 1, wherein the infrared sensor comprises an infrared-sensitive photodiode.

9. The touch panel system of claim 1, further comprising a select line and a readout line interconnected to the readout transistor.

10. The touch panel system of claim 9, wherein:

when a voltage is imposed on the select line, a voltage on the readout line is coupled to the infrared sensor and the readout transistor resulting in a voltage potential across the capacitor.

11. The touch panel system of claim 9, wherein:

when a voltage is imposed on the select line to determine how much charge has leaked from the capacitor, the readout transistor turns on, and a charge flows from the readout line through the readout transistor to reset the voltage on the capacitor.

12. The touch panel system of claim 1, further comprising an operational amplifier that provides an output voltage associated with the charge needed to reset the voltage on the capacitor.

13. The touch panel system of claim 1, wherein a measure of the infrared radiation incident on a plurality of infrared sensors is processed to identify a detected infrared image.

14. The touch panel system of claim 1, further comprising a display configured to display an image viewable via the touchable surface of the touch panel system.

8. The touch panel system of claim 8, wherein an anode of the infrared-sensitive photodiode is interconnected to a common bias line which is interconnected to a plurality of pixel circuits.

15. A touch panel system comprising:

a touchable surface;

at least one infrared source integrated in the touch panel system and configured to direct infrared radiation towards and through the touchable surface for illuminating one or more objects that are in contact with or adjacent to the touchable surface with infrared radiation; and

a display configured to display an image viewable via the touchable surface of the touch panel system, the display having an active matrix layer comprising;

a set of select lines corresponding to pixels of the display;

an infrared sensor that is sensitive to infrared radiation incident on the infrared sensor which is directed by the at least one infrared source towards and through the touchable surface and reflected from above the touchable surface by the one or more objects;

a readout transistor interconnected to the infrared sensor, a select line, and a readout line; and

a capacitor interconnected to the infrared sensor and the readout transistor, wherein a voltage imposed on the capacitor discharges through the infrared sensor if infrared radiation is incident on the infrared sensor, a charge to reset the voltage on the capacitor flows from the readout line through the readout transistor, and a measure of the infrared radiation incident on the infrared sensor is output based on the charge needed to reset the voltage on the capacitor.

16. The touch panel system of claim 15, wherein the infrared sensor comprises one of an infrared-sensitive thin film transistor and an infrared-sensitive photodiode.

17. The touch panel system of claim 15, wherein the display comprises one of a liquid crystal display and an organic light emitting diode display.

18. The touch panel system of claim 15, wherein the active matrix layer comprises a semiconductor material that is sensitive to infrared radiation.

19. A method performed in a touch panel system, the method comprising:

directing infrared radiation from at least one infrared source integrated in the touch panel system towards and through a touchable surface of the touch panel system for illuminating one or more objects that are in contact with or adjacent to the touchable surface with infrared radiation;

detecting infrared radiation incident on the infrared sensor which is directed by the at least one infrared source towards and through the touchable surface and reflected from above the touchable surface by the one or more objects;

discharging a voltage imposed on a capacitor through the infrared sensor if infrared radiation is incident on the infrared sensor;

resetting the voltage on the capacitor; and

outputting a measure of the infrared radiation incident on the infrared sensor based on the charge needed to reset the voltage on the capacitor.

20. The method of claim 19, further comprising:

displaying an image viewable via the touchable surface of the touch panel system;

identifying locations of different objects that are in contact with the touchable surface;

distinguishing between the objects; and

altering the image based on the locations of the different objects.