Light sensitive circuit, light sensing panel having the light sensitive circuit and display apparatus having the light sensing panel

Patent metadata

Field	Value
Publication number	US-9709439-B2
Application number	US-201414286286-A
Country	US
Kind code	B2
Filing date	May 23, 2014
Priority date	Aug 6, 2013
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

A light sensitive circuit includes a light sensing capacitor and a driving transistor. The light sensing capacitor is configured to sense light of a predetermined one or more wavelengths. The driving transistor includes a gate electrode electrically connected to the light sensing capacitor and is configured to generate a light sensing current according to a voltage of the gate electrode in the driving transistor. A light sensing accuracy and a light sensing signal to noise ratio (SNR) of the display apparatus including a plurality of such light sensing capacitors may be improved relative to ones that do not include such light sensing capacitors.

First claim

What is claimed is:

1. A light sensitive circuit comprising:
a light sensitive capacitor configured to change its charge storing characteristics in response to received light of a predetermined one or more wavelengths;
a driving transistor including a gate electrode electrically connected to the light sensitive capacitor; and
a first switching transistor configured to be driven in response to an (n+1)-th (n is a natural number) gate signal which is activated in succession after activation of an n-th gate signal and to transfer a driving reference voltage to the gate electrode in the driving transistor, the driving reference voltage being a predetermined reference voltage, the n-th and (n+1)-th gate signals being signals generated by drive circuitry of the display panel,
wherein the first switching transistor is a photo transistor that is responsive to a predetermined one or more wavelengths of light, and
wherein the first switching transistor is directly connected to the driving transistor.

2. The light sensitive circuit of claim 1 , wherein the light sensitive capacitor and the driving transistor are formed in a pixel unit of a display panel configured for displaying an image.

3. The light sensitive circuit of claim 1 , further comprising:
a coupling capacitor electrically connected to a gate electrode of the first switching transistor, to the gate electrode of the driving transistor and to the light sensitive capacitor.

4. The light sensitive circuit of claim 1 , further comprising:
a second switching transistor configured to be driven in response to the n-th gate signal and to transfer a light sensing current generated by the driving transistor to a readout line.

5. The light sensitive circuit of claim 1 , wherein a capacitance of the light sensitive capacitor is increased in proportion to an intensity of light of a predetermined one or more wavelengths received by the light sensitive capacitor.

6. A light sensing panel comprising:
a light sensitive circuit comprising a light sensitive capacitor configured to change its charge storing characteristics in response to received light of a predetermined one or more wavelengths, a driving transistor including a gate electrode electrically connected to the light sensitive capacitor and configured to generate a light sensing current according to a voltage of the gate electrode in the driving transistor, and a first switching transistor configured to be driven in response to an (n+1)-th (n is a natural number) gate signal next to an n-th gate signal and to transfer a driving reference voltage which is a reference voltage of the driving transistor to the gate electrode of the driving transistor;
a plurality of gate lines configured for transferring the n-th gate signal and the (n+1)-th gate signal; and
a plurality of data lines intersecting with the gate lines and configured for transferring data signals,
wherein the first switching transistor is a photo transistor configured for sensing light of a predetermined one or more wavelengths, and
wherein the first switching transistor is directly connected to the driving transistor.

7. The light sensing panel of claim 6 , further comprising: a readout line configured for transferring the light sensing current.

8. The light sensing panel of claim 7 , wherein the light sensitive circuit further comprises a second switching transistor configured to be driven in response to the n-th gate signal and to transfer the light sensing current generated by the driving transistor to the readout line.

9. The light sensing panel of claim 6 , wherein the light sensing panel is a display panel configured for displaying an image.

10. The light sensing panel of claim 9 , further comprising:
a thin film transistor including a gate electrode electrically connected to the gate line, and a source electrode electrically connected to the data line;
a liquid crystal capacitor electrically connected to a drain electrode of the thin film transistor; and
a storage capacitor electrically connected to the drain electrode of the thin film transistor.

11. The light sensing panel of claim 9 , further comprising:
a switching thin film transistor electrically connected to the gate line and the data line;
a driving thin film transistor electrically connected to the switching thin film transistor and a power line;
an organic light emitting diode electrically connected to the driving thin film transistor; and
a storage capacitor electrically connected to the switching thin film transistor and the power line.

12. The light sensing panel of claim 6 , wherein the light sensitive circuit further comprises a coupling capacitor electrically connected to a gate electrode of the first switching transistor, the gate electrode of the driving transistor and the light sensing capacitor.

13. The light sensing panel of claim 6 , wherein a capacitance of the light sensitive capacitor is increased in proportion to an intensity of received light of a predetermined one or more wavelengths.

14. A display apparatus comprising:
a light sensing panel comprising a light sensitive circuit comprising a light sensing capacitor configured to sense light, a driving transistor including a gate electrode electrically connected to the light sensing capacitor and configured to generate a light sensing current according to a voltage of the gate electrode in the driving transistor and a first switching transistor configured to be driven in response to an (n+1)-th (n is a natural number) gate signal next to an n-th gate signal and transfer a driving reference voltage which is a reference voltage of the driving transistor to the gate electrode of the driving transistor, gate lines transferring the n-th gate signal and the (n+1)-th gate signal, and data lines intersecting with the gate lines and transferring data signals;
a gate driving part configured to output the n-th gate signal and the (n+1)-th gate signal to the gate lines; and
a data driving part configured to output data signals to the data lines,
wherein the first switching transistor is a photo transistor configured for sensing light of a predetermined one or more wavelengths, and
wherein the first switching transistor is directly connected to the driving transistor.

15. The display apparatus of claim 14 , wherein the light sensing panel further comprises a readout line transferring the light sensing current.

16. The display apparatus of claim 15 , further comprising:
a readout circuit part electrically connected to the readout line, and configured to receive the light sensing current to output an output voltage corresponding to the light sensing current.

17. The display apparatus of claim 16 , wherein the readout circuit part comprises:
an amplifier including an inverting terminal to which the light sensing current is applied, a non-inverting terminal to which an amplifier reference voltage is applied, and an output terminal outputting the output voltage;
a feedback capacitor electrically connected between the inverting terminal of the amplifier and the output terminal of the amplifier; and
a switch configured to selectively connect the inverting terminal of the amplifier and the output terminal of the amplifier.

Assignees

• Samsung Display Co Ltd

Inventors

• Goh Joon-Chul
• Lim Jae-Keun

Classifications

• G06F3/0412

  Digitisers structurally integrated in a display · CPC title

• G01J2001/444

  Compensating; Calibrating, e.g. dark current, temperature drift, noise reduction or baseline correction; Adjusting · CPC title

• G01J2001/4473

  Phototransistor · CPC title

• H01L27/3227

  Electricity · mapped topic

• H01L27/3234

  Electricity · mapped topic