Sensing circuit, detection control method, fingerprint identification module and display apparatus

Patent metadata

Field	Value
Publication number	US-12020501-B2
Application number	US-202117781900-A
Country	US
Kind code	B2
Filing date	Jun 18, 2021
Priority date	Jun 18, 2021
Publication date	Jun 25, 2024
Grant date	Jun 25, 2024

Abstract

Sensing circuit, detection control method, fingerprint identification module and display apparatus are provided. The sensing circuit comprises a photoelectric conversion element, an energy storage circuit, a switch control circuit, a discharge control circuit and a voltage conversion circuit. The photoelectric conversion element controls potential of first terminal of energy storage circuit according to received optical signal; the switch control circuit controls first terminal of energy storage circuit to be connected to or disconnected from conversion control node; the discharge control circuit controls conversion control node be connected to or disconnected from first voltage terminal; the voltage conversion circuit controls to output voltage signal outputted by output terminal according to second and/or third voltage signals. In the disclosure, by performing fingerprint identification by detecting duration length of the fourth voltage signal from output terminal, fingerprint image information can be obtained simply and efficiently, thereby improving fingerprint identification accuracy and preventing interference.

First claim

What is claimed is:

1. A sensing circuit, comprising: a photoelectric conversion element, an energy storage circuit, a switch control circuit, a discharge control circuit, and a voltage conversion circuit, wherein
a first terminal of the energy storage circuit is electrically connected to the photoelectric conversion element, and the energy storage circuit is configured to store electrical energy;
the photoelectric conversion element is configured to control a potential of the first terminal of the energy storage circuit according to a received optical signal;
the switch control circuit is electrically connected to a switch control line, the first terminal of the energy storage circuit and a conversion control node, and the switch control circuit is configured to control the first terminal of the energy storage circuit to be connected to or disconnected from the conversion control node under the control of a switch control signal provided by the switch control line;
the discharge control circuit is electrically connected to the conversion control node and a first voltage terminal, and the discharge control circuit is configured to control the conversion control node to be connected to or disconnected from the first voltage terminal under the control of a potential of the conversion control node; and
the voltage conversion circuit is electrically connected to the conversion control node, a second voltage terminal, a third voltage terminal and an output terminal, and the voltage conversion circuit is configured to control, under the control of a second voltage signal provided by the second voltage terminal and the potential of the conversion control node, a voltage signal outputted by the output terminal according to the second voltage signal and/or a third voltage signal provided by the third voltage terminal.

2. The sensing circuit according to claim 1 , wherein the voltage conversion circuit comprises a first conversion circuit and a second conversion circuit;
the first conversion circuit is electrically connected to the conversion control node, the output terminal and the third voltage terminal, and the first conversion circuit is configured to control the output terminal to be connected to or disconnected from the third voltage terminal under the control of the potential of the conversion control node; and
the second conversion circuit is electrically connected to the second voltage terminal and the output terminal, and the second conversion circuit is configured to control the output terminal to be connected to or disconnected from the second voltage terminal under the control of the second voltage signal provided by the second voltage terminal.

3. The sensing circuit according to claim 1 , wherein the first conversion circuit comprises a first transistor; and
a control electrode of the first transistor is electrically connected to the conversion control node, a first electrode of the first transistor is electrically connected to the output terminal, and a second electrode of the first transistor is electrically connected to the third voltage terminal.

4. The sensing circuit according to claim 1 , wherein the second conversion circuit comprises a second transistor; and
a control electrode of the second transistor and a first electrode of the second transistor are electrically connected to the second voltage terminal, and a second electrode of the second transistor is electrically connected to the output terminal.

5. The sensing circuit according to claim 1 , wherein the photoelectric conversion element comprises a photodiode, and the energy storage circuit comprises a storage capacitor; a first terminal of the storage capacitor is the first terminal of the energy storage circuit; and
a cathode of the photodiode is electrically connected to the first terminal of the storage capacitor, an anode of the photodiode is electrically connected to a second terminal of the storage capacitor, and the second terminal of the storage capacitor is electrically connected to a bias voltage terminal.

6. The sensing circuit according to claim 1 , wherein the switch control circuit comprises a third transistor; and
a control electrode of the third transistor is electrically connected to the switch control line, a first electrode of the third transistor is electrically connected to the conversion control node, and a second electrode of the third transistor is electrically connected to a first terminal of the energy storage circuit.

7. The sensing circuit according to claim 1 , wherein the discharge control circuit comprises a fourth transistor; and
a first electrode of the fourth transistor is electrically connected to the first voltage terminal, and a control electrode of the fourth transistor and a second electrode of the fourth transistor are electrically connected to the conversion control node.

8. A detection control method, applied to the sensing circuit according to claim 1 , wherein a detection period comprises a reset stage and a detection stage arranged in sequence; the detection stage comprises a discharge time segment and a holding time segment; the detection control method comprises:
in the reset stage, controlling, by the switch control circuit, the first terminal of the energy storage circuit to be the disconnected from the conversion control node under the control of the switch control signal, and controlling, by the voltage conversion circuit under the control of the second voltage signal and the potential of the conversion control node, to output the second voltage signal through the output terminal;
at the beginning of the discharge time segment, controlling, by the switch control circuit, the first terminal of the energy storage circuit to be connected to the conversion control node under the control of the switch control signal, and controlling, by the photoelectric conversion element, the potential of the first terminal of the energy storage circuit to be changed according to the received optical signal, and controlling, by the voltage conversion circuit under the control of the second voltage signal and the potential of the conversion control node, to output a fourth voltage signal through the output terminal according to the second voltage signal and the third voltage signal;
in the discharge time segment, controlling, by the discharge control circuit, the conversion control node to be connected to the first voltage terminal under the control of the potential of the conversion control node, so that charges stored in the energy storage circuit is discharged to the first voltage terminal so as to change the potential of the conversion control node accordingly, and wherein the discharge time segment is ended when the second voltage signal is controlled, by the voltage conversion circuit under the control of the potential of the conversion control node, to be outputted through the output terminal; and
in the holding time segment, controlling, by the voltage conversion circuit, to output the second voltage signal through the output terminal under the control of the potential of the conversion control node.

9. The detection control method according to claim 8 , wherein the voltage conversion circuit comprises a first conversion circuit and a second conversion circuit;
the step of controlling, by the voltage conversion circuit under the control of the second voltage signal and the potential of the conversion control node, to output the second voltage signal through the output terminal comprises:
controlling, by the first conversion circuit under the control of the potential of the conversion control node, the output terminal to be disconnected from the third voltage terminal; controlling, by the second conversion circuit under

Assignees

• Beijing Boe Sensor Technology Co Ltd
• Boe Technology Group Co Ltd

Inventors

• Chen Chao
• Xu Shuai
• Zhang Wenchen
• Zhao Bin
• Du Xiaoqian
• Fan Luyao
• Xu Binbin
• Zhao Zhenqian
• Wu Junyu
• Zhang Jingshu

Classifications

• H10F77/90

  Energy storage means directly associated or integrated with photovoltaic cells, e.g. capacitors integrated with photovoltaic cells · CPC title

• H10F77/953

  for devices having potential barriers · CPC title

• G06V40/1318 Primary

  using electro-optical elements or layers, e.g. electroluminescent sensing · CPC title

• H03K17/6871

  the output circuit comprising more than one controlled field-effect transistor · CPC title

• G06F3/0412 Primary

  Digitisers structurally integrated in a display · CPC title