Multi-purpose Thin Film Optoelectric Sensor

• US 20150369661A1
• Filed: 09/23/2014
• Published: 12/24/2015
• Est. Priority Date: 06/23/2014
• Status: Active Grant

• Current Assignee: Shanghai OXi Technology Co., Ltd.
• Original Assignee: Shanghai OXi Technology Co., Ltd.
• Inventors: Lin, Weiping
• Granted Patent: US 9,501,686 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06V 40/1318 using electro-optical elements or layers, e.g. electroluminescent sensing

Abstract

An optoelectric sensor, comprising: a light-sensitive structure which comprises a substrate and an array of pixel cells located on the substrate, wherein each of the pixel cells comprises a thin film transistor and a photodiode; a fiber optical guide plate located above the light-sensitive structure, which comprises a group of optical fiber bundles configured to be perpendicular to the substrate, and each of the optical fiber bundles has an diameter smaller than or equal to a width of pixel cell; and a backlight source located below the light-sensitive structure. The fiber plate will enable each pixel cell detecting features of an object surface corresponding thereto more independently, so as to improve the resolution of the optoelectric sensor. The optical fiber bundles are configured to be perpendicular to the substrate, and the optoelectric sensor will have a thin structure.

Claims

1. A optoelectric sensor, comprising:

a light-sensitive structure which comprises a substrate and an array of pixel cells located on the substrate, wherein each of the pixel cells comprises a thin film transistor and a photodiode;

a fiber optic guide plate located on top of the light-sensitive structure, wherein the fiber optical guide plate comprises an array of optical fiber bundles which are configured to be perpendicular to the substrate, and each of the optical fiber bundles has a diameter smaller than or equal to a width of its corresponding pixel cell; and

a backlight source located underneath the light-sensitive structure, which is adapted to emitting lights to penetrate through the light-sensitive structure and the fiber optical guide plate.

2. The optoelectric sensor according to claim 1, wherein the substrate has a first region and a second region, the thin film transistor is located on the first region, and the photodiode is located on the second region.

3. The optoelectric sensor according to claim 2, wherein the thin film transistor comprises:

a gate located on the first region of the substrate;

a first insulating layer covering the gate;

a channel layer located on the first insulating layer;

a first electrode and a second electrode which are both located on the channel layer, wherein a gap which partially exposes the channel layer is formed between the first electrode and the second electrode; and

a second insulating layer covering the first electrode, the second electrode and the channel layer.

4. The optoelectric sensor according to claim 3, wherein the photodiode comprises:

a N doped semiconductor layer, an intrinsic semiconductor layer and a P doped semiconductor layer which are successively located on the second region of the substrate, wherein the N doped semiconductor layer serves as a cathode of the photodiode, the intrinsic semiconductor layer serves as a light-absorb layer of the photodiode, and the P doped semiconductor layer serves as a anode of the photodiode.

5. The optoelectric sensor according to claim 3, wherein the photodiode comprises:

a N doped semiconductor layer located on the second region of the substrate; and

a P doped semiconductor layer which is located on the N doped semiconductor layer and contacted with the N doped semiconductor layer.

6. The optoelectric sensor according to claim 4, wherein the first insulating layer, the second electrode and the second insulating layer of the thin film transistor extend to the second region of the substrate, the second insulating layer located on the second region of the substrate has an opening which exposes the second electrode, and the N doped semiconductor layer of the photodiode covers a surface of the second electrode in the opening.

7. The optoelectric sensor according to claim 6, further comprising:

a first barrier layer disposed between the substrate and the first insulating layer which extends to the second region of the substrate for blocking the lights emitted by the backlight source from entering into the photodiode,

wherein the first barrier layer is located below the N doped semiconductor layer, and has a size lager than that of the N doped semiconductor layer, and

wherein an aperture is formed in the first barrier layer between two of the pixel cells, the aperture is used to allow the lights emitted from the backlight source entering into the light-sensitive structure and irradiating to the optical fiber plate there through.

8. The optoelectric sensor according to claim 4, further comprising a contact electrode disposed on the P doped semiconductor layer of the photodiode, wherein the contact electrode comprises a non-opaque conductive material.

9. The optoelectric sensor according to claim 8, wherein the first barrier layer comprises metal, and the first barrier layer, along with the N doped semiconductor layer and a contact electrode of the photodiode, constitute a storage capacitor.

10. The optoelectric sensor according to claim 9, further comprising:

a third insulating layer disposed on the second insulating layer of the thin film transistor for overlaying the photodiode and exposing a surface of the contact electrode.

11. The optoelectric sensor according to claim 10, wherein the substrate, the first insulating layer, the second insulating layer and the third insulating layer all comprise a non-opaque material.

12. The optoelectric sensor according to claim 10, further comprising:

a second light-block barrier layer disposed on the third insulating layer for covering the thin film transistor, wherein the second light-block barrier layer exposes the surface of the contact electrode of photodiode, and the second light-block barrier layer also exposes the aperture so as to allow the lights emitted from the backlight source entering into the light-sensitive structure and irradiating to the fiber optic plate.

13. The optoelectric sensor according to claim 8, further comprising:

a connect electrode disposed on each contact electrode for electrically connecting the contact electrode of each pixel cell, wherein the connect electrode comprises non-opaque conductive material for allowing incident lights from the fiber optic guide plate entering into the photodiode.

14. The optoelectric sensor according to claim 8, wherein the pixel cells are arranged in an array, and the optoelectric sensor further comprises:

a driving chip, located on the light-sensitive structure and connected with an external power source;

a signal sensing chip, located on the light-sensitive structure and connected with the external power source;

a number of gate lines, each of which has one end connected with the gates of the thin film transistors which are in a same line, and another end connected with the driving chip, so as to provide a scanning voltage to the gates of the thin film transistors, wherein the scanning voltage is used to open or close the thin film transistor;

a number of data lines, each of which has one end connected with the first electrodes which are in a same row, and another end connected with the reading chip, so as to provide a base voltage to the first electrodes;

a group of biasing voltage lines , each of which has one end connected with the connect electrodes which are in the same row, and another end connected with the external power source, so as to provide a biasing voltage to the contact electrodes, wherein the biasing voltage and the base voltage are used to form a reverse bias voltage in the photodiode; and

an array of metal lines, each of which has one end connected with the first barrier layers which are in the same line, and another end connected with the voltage biasing lines, so as to provide an external voltage which is used to make the first barrier layer along with the N doped semiconductor layer and the contacting electrode of the photodiode to constitute a storage capacitor.

15. The optoelectric sensor according to claim 14, wherein the scanning voltage ranges from −

10 volt to 15 volt, the base voltage ranges from 0 volt to 3 volt, the biasing voltage ranges from 0 volt to −

10 volt, and the external voltage ranges from 0 volt to −

10 volt.

16. The optoelectric sensor according to claim 1, wherein the fiber optic guide plate has a thickness ranging from 0.2 mm to 10 mm.

17. The optoelectric sensor according to claim 1, wherein the backlight source comprises at least one LED lamp selected from red light LED lamp, blue light LED lamp, green light LED lamp, white light LED lamp, infrared LED lamp and ultraviolet LED lamp, or only one LED lamp with a wavelength ranging from 300 nm to 1000 nm.

18. The optoelectric sensor according to claim 17, wherein the LED lamp emits lights by way of impulse.

19. The optoelectric sensor according to claim 17, wherein the LED lamp emits lights in a continuous way.

20. The optoelectric sensor according to claim 1, wherein the light-sensitive structure and the optical fiber plate are combined using glue or bond by mechanical bonding.