Fingerprint identification sensor, fingerprint identification method and electronic device

Patent metadata

Field	Value
Publication number	US-10430635-B2
Application number	US-201715767704-A
Country	US
Kind code	B2
Filing date	Sep 30, 2017
Priority date	Apr 18, 2017
Publication date	Oct 1, 2019
Grant date	Oct 1, 2019

Abstract

A fingerprint identification sensor, a fingerprint identification method and an electronic device are disclosed. The fingerprint identification sensor includes a substrate; a fingerprint sensing element disposed on the substrate and including a thin film transistor, an off-state leakage current of the thin film transistor varying with the intensity of light irradiating onto an active area thereof; and a fingerprint identification light source arranged to emit light that irradiates onto a finger and is reflected thereby, the reflected light irradiating onto the active area of the thin film transistor. Thus, the fingerprint identification can be realized conveniently, and the fingerprint identification sensor has at least one of the advantages like high sensitivity and simple structure.

First claim

What is claimed is:

1. A fingerprint identification sensor, comprising:
a substrate;
a fingerprint sensing element disposed on the substrate and including a thin film transistor, an off-state leakage current of the thin film transistor at an off-state voltage applied to a gate of the thin film transistor varying with the intensity of light irradiating onto an active area thereof, the fingerprint sensing element being configured to generate a sensing signal based on the off-state leakage current; and
a fingerprint identification light source arranged to emit light that irradiates onto a finger and is reflected thereby, the reflected light irradiating onto the active area of the thin film transistor.

2. The fingerprint identification sensor according to claim 1 , further comprising a plurality of the fingerprint sensing elements evenly distributed on the substrate.

3. The fingerprint identification sensor according to claim 1 , wherein the material of the active area of the thin film transistor has a band-gap width of less than 2 eV.

4. The fingerprint identification sensor according to claim 3 , wherein the material of the active area absorbs light emitted from the fingerprint identification light source with an absorption coefficient of more than 10 5 cm −1 .

5. The fingerprint identification sensor according to claim 3 , wherein the active area of the thin film transistor comprises at least one of amorphous silicon, ITZO and ITEO.

6. The fingerprint identification sensor according to claim 1 , wherein the fingerprint identification light source comprises an OLED light source.

7. The fingerprint identification sensor according to claim 6 , wherein the OLED light source is insulated from the thin film transistor.

8. The fingerprint identification sensor according to claim 7 , wherein an anode of the OLED is arranged on an insulating layer of the thin film transistor.

9. The fingerprint identification sensor according to claim 6 , further comprising an OLED driving circuit connected to the anode of the OLED so as to drive the OLED to irradiate.

10. The fingerprint identification sensor according to claim 1 , further comprising a differential amplifier circuit connected to a drain of the thin film transistor so as to amplify a leakage current signal of the drain.

11. The fingerprint identification sensor according to claim 1 , wherein, at off-state voltage of the thin film transistor, the leakage currents corresponding to the reflected lights generated by a valley and a ridge of the finger differ by no less than three orders of magnitude.

12. An electronic device, comprising the fingerprint identification sensor according to claim 1 .

13. A fingerprint identification method using a fingerprint identification sensor,
wherein the fingerprint identification sensor comprises a substrate; a fingerprint sensing element disposed on the substrate and including a thin film transistor, an off-state leakage current of the thin film transistor at an off-state voltage applied to a gate of the thin film transistor varying with the intensity of light irradiating onto an active area thereof; and a fingerprint identification light source arranged to emit light that irradiates onto a finger and is reflected thereby, the reflected light irradiating onto the active area of the thin film transistor,
the method comprising the steps of:
lighting the fingerprint identification light source so that light emitted from the fingerprint identification light source irradiates onto the finger and is reflected thereby; and
applying the off-state voltage to the gate of the thin film transistor, detecting the off-state leakage current of the thin film transistor, and generating a sensing signal based on the detected off-state leakage current in order to realize fingerprint identification.

14. The method according to claim 13 , wherein the lights reflected by different parts of the finger have different light intensities, and the leakage current varies with the light intensity of the reflected light.

15. The method according to claim 13 , wherein the leakage currents generated by the reflected lights at a valley and a ridge of the finger differ by no less than three orders of magnitude.

16. The method according to claim 13 , further comprising the step of: amplifying the leakage current by means of a differential amplifier circuit.

17. The method according to claim 13 , wherein the step of lighting the fingerprint identification light source further comprises the step of lighting the fingerprint identification light source by means of an OLED driving circuit connected to an anode of an OLED.

18. The fingerprint identification sensor according to claim 4 , wherein the active area of the thin film transistor comprises at least one of amorphous silicon, ITZO and ITEO.

Assignees

• Boe Technology Group Co Ltd

Inventors

• Ren Qingrong
• Yang Wei
• Sun Jianming
• Liu Yingwei
• Li Liangjian
• Wang Haisheng
• Liu Yingming

Classifications

• G06K9/00087

  Physics · mapped topic

• G06K9/0004 Primary

  Physics · mapped topic

• G06V40/1318 Primary

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

• G06V40/1365

  Matching; Classification · CPC title