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

• US 9,419,610 B2
• Filed: 12/13/2010
• Issued: 08/16/2016
• Est. Priority Date: 05/20/2010
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Ahn, Seung-eon, Park, Sung-ho, Song, I-hun, Jeon, Sang-hun
• Primary Examiner(s): LEE, JOHN R
• Application Number:
  US12/926,831
• Publication Number:
  US 20110284722A1
• Time in Patent Office: 2,073 Days
• Field of Search: 250/208.1, 257/431, 257/43, 257/57, 257/66, 257/462, 257/E31.079, 345/175
• US Class Current: 1/1
• 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 to the light-sensing transistor without a capacitor connected to a node between the light-sensing transistor and the switching transistor connected in series, the light-sensing transistor being a light-sensitive oxide semiconductor transistor including a light-sensitive oxide semiconductor as a channel layer, the light-sensing circuit being a pixel circuit;

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;

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

the light-sensing circuit being configured to apply a low voltage to the switching transistor via the first gate line and to apply a high voltage to the light-sensing transistor via the second gate line during a standby time, and

the light-sensing circuit being configured to apply the high voltage to the switching transistor via the first gate line and to apply the low voltage to the light-sensing transistor via the second gate line if data is output.

2. The light-sensing circuit of claim 1, 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.

3. The light-sensing circuit of claim 1, wherein the light-sensing transistor includes

a substrate,

an insulating layer on the substrate,

the gate of the light-sensing transistor on at least a portion of the insulating layer,

a gate insulating layer that covers at least a surrounding of the gate of the light-sensing transistor and is on the insulating layer and the gate of the light-sening transistor,

the channel layer on the gate insulating layer,

a source and the drain of the light-sensing transistor 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 the light-sensitive oxide semiconductor.

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

a substrate;

the channel layer on the substrate;

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

the gate of the light-sensing transistor on the gate insulating layer;

a source and the drain of the light-sensing transistor at an interval from the gate of the light-sensing transistor and on both sides of the gate of the light-sending transistor on the channel layer; and

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

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

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

6. The light-sensing circuit of claim 5, 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.

7. 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.

8. 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.

9. 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.

10. 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.

11. The light-sensing apparatus of claim 10, 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.

12. The light-sensing apparatus of claim 11, wherein the first and second gate lines are connected to the gate driver, and the data lines are connected to the data driver.

13. The light-sensing apparatus of claim 12, 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.

14. The light-sensing apparatus of claim 10, wherein the light-sensing apparatus is an image acquisition device, or a remote optical touch panel.

15. The light-sensing circuit of claim 1, wherein a source of the light-sensing transistor is connected to a drain of the switching transistor.

16. The light-sensing circuit of claim 1,

the light-sensing transistor includes source and drain electrodes, and

the light-sensitive oxide semiconductor is directly connected to the source and drain electrodes of the light-sensing transistor.

21. The light-sensing circuit of claim 4, wherein the source and drain are each formed of a material that is one of,

a conductive metal oxide that is different than a material of the light-sensitive oxide semiconductor, and

a conductive metal.

17. A light-sensing circuit comprising:

a light-sensing transistor configured to sense light;

a switching transistor connected in series with the light-sensing transistor,

the light-sensing transistor being a light-sensitive oxide semiconductor transistor including a light-sensitive oxide semiconductor as a channel layer, and

a source of the light-sensing transistor being configured to be electrically connected in series to a drain of the switching transistor independent of whether the switching transistor is on or off and independent of whether the light-sensing transistor is on or off;

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

a data line configured to be electrically connected to a source of the switching transistor independent of whether the switching transistor is on or off;

a driving voltage line configured to be electrically connected to a drain of the light-sensing transistor independent of whether the light-sensing transistor is on or off; and

a second gate line connected to a gate of the light-sensing transistor, wherein the driving voltage line and the second gate line are electrically separated from each other, and the light-sensing circuit is a pixel circuit, wherein

the light-sensing circuit is configured to apply a low voltage to the switching transistor via the first gate line and to apply a high voltage to the light-sensing transistor via the second gate line during a standby time,

the light-sensing circuit is configured to apply the high voltage to the switching transistor via the first gate line and to apply the low voltage to the light-sensing transistor via the second gate line if data is output through the switching transistor, and

the switching transistor is connected in series to the light-sensing transistor without a capacitor connected to a node between the light-sensing transistor and the switching transistor connected in series.

18. The light-sensing circuit of claim 17, wherein

the switching transistor does not have light-sensing characteristics.

19. The light-sensing circuit of claim 17, wherein

the light-sensitive oxide semiconductor is directly connected to the source and drain of the light-sensing transistor, and wherein

the light-sensing circuit is configured to apply a high voltage to the drain of the light-sensing transistor using the driving voltage line while simultaneously applying a low voltage of the to the gate of the light-sensing transistor.

20. The light-sensing circuit of claim 17, 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.

22. The light-sensing circuit of claim 17, wherein

the source and drain of the light-sensing transistor are each formed of a material that is one of,

a conductive metal oxide that is different than the light-sensitive oxide semiconductor in the channel layer, and

a conductive metal.