Light-sensing circuit, method of operating the light-sensing circuit, and light-sensing apparatus employing the light-sensing circuit

• US 20110284722A1
• Filed: 12/13/2010
• Published: 11/24/2011
• Est. Priority Date: 05/20/2010
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Song, I-hun, Park, Sung-ho, Jeon, Sang-hun, Ahn, Seung-eon
• Granted Patent: US 9,419,610 B2
• Time in Patent Office: Days
• US Class Current: 250/208.1
• CPC Class Codes: H03K 17/78 using opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled
• CPC Class Codes: H03K 17/941 using an optical detector H03K17/968 takes precedence

Abstract

Example embodiments are directed to a light-sensing circuit, a method of operating the light-sensing circuit, and a light-sensing apparatus including the light-sensing circuit. The light-sensing circuit includes a light-sensitive oxide semiconductor transistor that senses light; and a switching transistor connected to the light-sensing transistor in series and configured to output data. During a standby time, a low voltage is applied to the switching transistor and a high voltage is applied to the light-sensitive oxide semiconductor transistor, and when data is output, the high voltage is applied to the switching transistor and the low voltage is applied to the light-sensitive oxide semiconductor transistor.

Claims

1. A light-sensing circuit comprising:

a light-sensing transistor configured to sense light; and

a switching transistor connected in series with the light-sensing transistor and configured to output data,

wherein the light-sensing transistor is a light-sensitive oxide semiconductor transistor including a light-sensitive oxide semiconductor as a channel layer.

2. The light-sensing circuit of claim 1, further comprising:

a first gate line connected to a gate of the switching transistor;

a data line connected to a source of the switching transistor;

a driving voltage line connected to a drain of the light-sensing transistor; and

a second gate line connected to a gate of the light-sensing transistor.

3. The light-sensing circuit of claim 2, wherein, during a standby time, a low voltage is applied to the switching transistor via the first gate line and a high voltage is applied to the light-sensing transistor via the second gate line;

and, when data is output, the high voltage is applied to the switching transistor via the first gate line and the low voltage is applied to the light-sensing transistor via the second gate line.

4. The light-sensing circuit of claim 3, wherein the high voltage is a higher voltage among a positive voltage that removes charges trapped in the light-sensing transistor and a voltage that turns ON the switching transistor, and the low voltage is a lower voltage among a threshold voltage of the switching transistor and a threshold voltage of the light-sensing transistor.

5. The light-sensing circuit of claim 1, wherein the light-sensing transistor comprises:

a substrate;

an insulating layer on the substrate;

a gate on at least a portion of the insulating layer;

a gate insulating layer that covers at least a surrounding of the gate and is on the insulating layer and the gate;

a channel layer on the gate insulating layer;

a source and a drain respectively covering ends of the channel layer; and

a transparent insulating layer on the source, the drain, and the channel layer,

wherein the channel layer includes a light-sensitive oxide semiconductor.

6. The light-sensing circuit of claim 1, wherein the light-sensing transistor comprises:

a substrate;

a channel layer on the substrate;

a gate insulating layer on a center portion of the channel layer;

a gate on the gate insulating layer;

a source and a drain at an interval from the gate and on both sides of the gate on the channel layer; and

a transparent insulating layer on the gate, the source, and the drain,

wherein the channel layer includes a light-sensitive oxide semiconductor.

7. The light-sensing circuit of claim 1, wherein the light-sensitive oxide semiconductor includes a ZnO-based oxide.

8. The light-sensing circuit of claim 7, wherein the ZnO-based oxide includes ZnO or a mixture including ZnO and at least one material selected from a group consisting of Hf, Y, Ta, Zr, Ti, Cu, Ni, Cr, In, Ga, Al, Sn, and Mg.

9. The light-sensing circuit of claim 1, wherein a degree of sensitivity of the light-sensitive transistor is dependent on a color or a wavelength of light incident on the light-sensitive transistor.

10. The light-sensing circuit of claim 1, wherein a degree of sensitivity of the light-sensitive transistor is dependent on an intensity of light incident on the light-sensitive transistor.

11. The light-sensing circuit of claim 1, wherein a degree of sensitivity of the light-sensitive transistor is dependent on a color and an intensity of light incident on the light-sensitive transistor.

21. A light-sensing apparatus comprising:

a light-sensing panel configured to sense incident light;

a gate driver configured to provide a gate voltage to the light sensing panel;

a data driver configured to measure an output of the light sensing panel; and

an analog digital (A/D) converter (ADC) configured to convert an analog signal output by the data driver into a digital signal,

wherein the light-sensing panel includes an array of a plurality of light-sensing pixels, each of the light-sensing pixels including the light-sensing circuit of claim 1.

22. The light-sensing apparatus of claim 21, wherein the light-sensing panel further comprises:

a plurality of first gate lines and second gate lines as rows, and

a plurality of driving voltage lines and data lines as columns.

23. The light-sensing apparatus of claim 22, wherein the first and second gate lines are connected to the gate driver, and the data lines are connected to the data driver.

24. The light-sensing apparatus of claim 23, wherein the gate driver is configured to sequentially provide a gate voltage to rows of the light-sensing pixels via the first and second gate lines.

25. The light-sensing apparatus of claim 21, wherein the light-sensing apparatus is an image acquisition device, or a remote optical touch panel.

12. A method of operating a light-sensing circuit including a light-sensing transistor configured to sense light and a switching transistor configured to output data, the light-sensing transistor and the switching transistor connected in series, the method comprising:

performing a standby operation by applying a low voltage to a gate of the switching transistor and applying a high voltage to a gate of the light-sensing transistor; and

performing a data-outputting operation by applying the high voltage to the gate of the switching transistor, and applying the low voltage to the gate of the light-sensing transistor.

13. The method of claim 12, further comprising:

applying, as the high voltage, a higher voltage among a positive voltage that removes charges trapped in the light-sensing transistor and a voltage that turns ON the switching transistor.

14. The method of claim 12, further comprising:

applying, as the low voltage, a lower voltage among a threshold voltage of the switching transistor and a threshold voltage of the light-sensing transistor.

15. The method of claim 12, wherein, performing the standby operation includes:

outputting low signals from the switching transistor independent of light incident on the light-sensing transistor.

16. The method of claim 12, wherein, performing the data-output operation includes:

outputting a high signal from the switching transistor when light is incident on the light-sensing transistor, and

outputting a low signal from the switching transistor when light is not incident on the light-sensing transistor.

17. The method of claim 16, wherein, performing the data-output operation further includes:

outputting, by the switching transistor, the high signal proportional to an intensity of light incident on the light-sensing transistor.

18. The method of claim 12, wherein the light-sensing transistor is a light-sensitive oxide semiconductor transistor including a light-sensitive oxide semiconductor as a channel layer.

19. The method of claim 18, wherein the light-sensitive oxide semiconductor includes a ZnO-based oxide.

20. The light-sensing circuit of claim 19, wherein the ZnO-based oxide includes ZnO or a mixture including ZnO and at least one material selected from a group consisting of Hf, Y, Ta, Zr, Ti, Cu, Ni, Cr, In, Ga, Al, Sn, and Mg.