CN114078888A

CN114078888A - Optical fingerprint device

Info

Publication number: CN114078888A
Application number: CN202010817764.5A
Authority: CN
Inventors: 孙凌云; 夏欢; 左问
Original assignee: Galaxycore Shanghai Ltd Corp
Current assignee: Galaxycore Shanghai Ltd Corp
Priority date: 2020-08-14
Filing date: 2020-08-14
Publication date: 2022-02-22

Abstract

The invention provides an optical fingerprint device, which includes several microlenses and pixel units arranged oppositely. By arranging at least one light-blocking layer above the plane where the microlenses are located, the signal crosstalk caused by the large-angle incident light entering adjacent pixel units is reduced. , reducing the noise effect caused by large-angle stray light entering the pixel unit, improving the imaging quality and improving the fingerprint recognition effect.

Description

Optical fingerprint device

Technical Field

The present invention relates to an optical fingerprint device.

Background

The current fingerprint identification schemes include optical technology, silicon technology (capacitive/radio frequency type), ultrasonic technology, etc. Among them, the optical fingerprint recognition technology is to image a fingerprint by using an image sensor, and has been widely used in portable electronic devices.

The conventional optical fingerprint identification system basically utilizes the total reflection principle, light emitted by a light source irradiates the outer surface of a light-transmitting layer (such as organic and inorganic glass) pressed with a fingerprint, reflected light is obtained by an image sensor, and the amount of the reflected light depends on the depth of fingerprint ridges and valleys pressed on the outer surface of the glass, and grease and moisture between skin and the glass. The light is reflected to the image sensor by the interface between the glass and the air after the light is emitted to the center of the valley through the glass, and the light emitted to the ridge is not reflected by the total reflection but is absorbed by the contact surface between the ridge and the glass or reflected to other center in a diffused manner, so that the image of the fingerprint is formed on the image sensor.

The imaging principle of the under-screen optical fingerprint system using an OLED (organic light emitting diode) display screen is different. The light emitted by the OLED display screen is irradiated to the finger fingerprint which is in direct contact with the display screen or is near the display screen and then returns to the display screen, due to the fact that the distances between the fingerprint valley ridges and the display screen are different, information carried in the returned light can include spatial patterns, positions and the like of the fingerprint valley ridges, the light is received by pixel units of an image sensor located below the display screen, and therefore an image containing the information of the fingerprint valley ridges is formed.

The optical fingerprint device in the prior art generally comprises a plurality of microlenses and pixel units which are arranged oppositely, and light blocking layers are arranged between the adjacent microlenses and between the microlenses and the pixel units so as to prevent light rays from entering photodiodes of the adjacent pixel units to cause signal crosstalk between the pixel units and further influence fingerprint identification effect.

However, the light blocking layer in the optical fingerprint device in the prior art can only block incident light with a small angle from entering an adjacent pixel unit, when the incident light angle is large, the blocking effect of the light blocking layer is limited, and it is unavoidable that incident light with a large angle enters an adjacent pixel unit to cause signal crosstalk, and stray light with a large angle also easily enters a photodiode of the pixel unit, thereby generating noise and reducing imaging quality, therefore, how to improve the signal-to-noise ratio of the system directly affects the fingerprint identification effect, especially the fingerprint identification effect of dry fingers.

Disclosure of Invention

The invention aims to provide an optical fingerprint device, which reduces signal crosstalk caused by large-angle incident light entering adjacent pixel units, reduces noise influence caused by large-angle stray light entering the pixel units, improves imaging quality and improves fingerprint identification effect.

In view of the above, the present invention provides an optical fingerprint device comprising: a plurality of microlenses and pixel units which are arranged oppositely; at least one light blocking layer is arranged above the plane of the micro lens.

Preferably, a support structure is arranged between the microlenses, at least one euphotic layer is arranged above the support structure, and a light blocking layer is arranged on the surface of the euphotic layer or between the euphotic layers.

Preferably, the lowermost light transmitting layer is bonded to the support structure.

Preferably, at least one light blocking layer is arranged below the plane of the micro lens.

Preferably, an infrared cut filter film is arranged on the surface of the light-transmitting layer or between the multiple light-transmitting layers.

Preferably, at least one light blocking layer is arranged above the infrared cut-off filter film.

Preferably, at least one light transmitting layer is arranged below the plane of the micro lens, and an infrared cut-off filter film is arranged on the surface of the light transmitting layer or between the light transmitting layers.

Preferably, a pad is arranged around the pixel unit, and the pad is exposed by cutting and removing the light-transmitting layer.

Preferably, the surface of the pixel unit is provided with an inner lens.

Preferably, the openings formed in the light blocking layer for light to pass through are gradually reduced from top to bottom.

Preferably, the light-transmitting layer comprises glass, an organic dry film or a light-transmitting adhesive.

Preferably, the refractive index of the light transmitting layer close to the microlens is smaller than the refractive index of the light transmitting layer far from the microlens and the refractive index of the microlens.

Preferably, each microlens corresponds to one or more pixel units.

The optical fingerprint device comprises a plurality of microlenses and pixel units which are arranged oppositely, and at least one light blocking layer is arranged above the plane where the microlenses are located, so that signal crosstalk caused by the fact that large-angle incident light enters the adjacent pixel units is reduced, noise influence caused by the fact that large-angle stray light enters the pixel units is reduced, imaging quality is improved, and fingerprint identification effect is improved.

Drawings

Other features, objects and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments thereof, which proceeds with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of an optical fingerprint device according to one embodiment of the present invention;

fig. 2 is a schematic structural diagram of an optical fingerprint device according to another embodiment of the present invention.

In the drawings, like or similar reference numbers indicate like or similar devices (modules) or steps throughout the different views.

Detailed Description

In order to solve the problems in the prior art, the invention provides an optical fingerprint device which comprises a plurality of microlenses and pixel units which are arranged oppositely, wherein at least one light blocking layer is arranged above the plane where the microlenses are located, so that signal crosstalk caused by large-angle incident light entering adjacent pixel units is reduced, noise influence caused by large-angle stray light entering the pixel units is reduced, imaging quality is improved, and a fingerprint identification effect is improved.

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof. The accompanying drawings illustrate, by way of example, specific embodiments in which the invention may be practiced. The illustrated embodiments are not intended to be exhaustive of all embodiments according to the invention. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

The present invention will be described in detail with reference to specific examples.

Fig. 1 shows a preferred embodiment of the optical fingerprint device of the present invention comprising several pixel cells 101 arranged in a semiconductor substrate 100, wherein each pixel cell 101 comprises a photodiode 104, a metal interconnect layer 103, an inner lens 102. In other embodiments not shown, the optical fingerprint device may also include pixel cells without an inner lens. In addition, the optical fingerprint device further comprises a plurality of micro lenses 105 arranged opposite to the pixel unit 101. Specifically, each microlens 105 may correspond to one or more pixel units 101.

Different from the prior art, in the optical fingerprint device of the invention, at least one light blocking layer 106 is arranged above the plane where the micro lens 105 is located, so as to reduce signal crosstalk caused by large-angle incident light entering the adjacent pixel unit 101, and reduce noise influence caused by large-angle stray light entering the pixel unit 101, thereby improving imaging quality and fingerprint identification effect.

Specifically, support structures 107 are disposed between the microlenses 105, and at least one light-transmitting layer 108, here shown as three light-transmitting layers 108, is disposed above the support structures 107, wherein the lowest light-transmitting layer 108 is bonded to the support structures 107 by adhesion, and the other light-transmitting layers 108 may be formed by adhesion or coating. Preferably, the refractive index of the light-transmitting layer 108 close to the microlens 105 is smaller than the refractive index of the light-transmitting layer 108 far from the microlens 105 and the refractive index of the microlens 105, so as to achieve a better focusing effect on incident light. The transparent layer 108 may be made of glass, organic dry film or transparent adhesive. The material of the supporting structure 107 may be the same as or different from that of the transparent layer 108.

The light blocking layer 106 is arranged on the surface of the light transmitting layer 108 or between the multiple light transmitting layers 108, and the light blocking layer 106 is arranged above the plane where the micro lens 105 is located, so that signal crosstalk caused by the fact that large-angle incident light enters the adjacent pixel unit 101 can be effectively reduced, and the noise influence caused by the fact that large-angle stray light enters the pixel unit 101 is reduced, so that the imaging quality is greatly improved, and the fingerprint identification effect is improved.

Preferably, an infrared cut filter 110, here shown as two layers of infrared cut filters 110, is further disposed on the surface of the light-transmitting layer 108 or between the light-transmitting layers 108 to reduce noise crosstalk and image distortion caused by infrared light in incident light entering the pixel unit. Preferably, at least one light-blocking layer 106 is disposed above the infrared cut filter 110.

In addition, there is at least one light transmitting layer 109, here shown as three light transmitting layers 109, below the plane of the microlenses 105. Similarly, the material of the light-transmitting layer 109 may be glass, an organic dry film, or a light-transmitting adhesive. At least one infrared cut filter 112, here shown as one infrared cut filter 112, is further disposed on the surface of the light-transmitting layer 109 or between the light-transmitting layers 109, so as to further improve the filtering effect on the infrared light in the incident light. At least one light blocking layer 111 is further disposed on the surface of the light transmitting layer 109 or between the light transmitting layers 109, that is, at least one light blocking layer 111, here shown as two light blocking layers 111, is disposed below the plane where the micro lens 105 is located, so as to further improve the blocking effect on the incident light with large angle and the stray light.

In this embodiment, the size of the opening for light passing formed by the light-blocking layer 106 disposed above the plane of the microlens 105 is substantially the same, and the size of the opening for light passing formed by the light-blocking layer 111 disposed below the plane of the microlens 105 is gradually reduced from top to bottom. In other embodiments not shown, the size of the opening formed by the light blocking layer 106 disposed above the plane of the microlens 105 for light to pass through may also be gradually reduced from top to bottom, so as to better block the large-angle incident light and the stray light.

In addition, in the optical fingerprint device of the present invention, a pad (not shown) may be further disposed around the pixel unit 101, and during the formation of the optical fingerprint device, the pad may be exposed by removing the light transmissive layer 109 through mechanical cutting or laser cutting, so as to be electrically connected with an external circuit through the pad.

Those skilled in the art will appreciate that the number and positions of the light-transmitting layer 108, the light-blocking layer 106, the ir-cut filter 110 above the plane of the microlenses 105, and the light-transmitting layer 109, the light-blocking layer 111, and the ir-cut filter 112 below the plane of the microlenses 105 can be selected according to actual needs, for example, fig. 2 shows another preferred embodiment.

Furthermore, in the preferred embodiment shown in fig. 2, the light-transmitting layer 109 closest to the pixel units 101 may cover only the regions between the pixel units 101, but not the regions where the pixel units 101 are located, that is, the light-transmitting layer 109 closest to the pixel units 101 may also serve to support the upper layer structure as the supporting structures 107 between the microlenses 105.

In summary, the optical fingerprint device of the present invention includes a plurality of microlenses and pixel units that are arranged oppositely, and at least one light blocking layer is arranged above the plane where the microlenses are located, so that signal crosstalk caused by large-angle incident light entering adjacent pixel units is reduced, noise influence caused by large-angle stray light entering the pixel units is reduced, imaging quality is improved, and fingerprint identification effect is improved.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. Furthermore, it will be obvious that the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. Several elements recited in the apparatus claims may also be implemented by one element. The terms first, second, etc. are used to denote names, but not any particular order.

Claims

1. an optical fingerprint device, is characterized in that, comprises:

Several microlenses and pixel units arranged oppositely;

There is at least one light blocking layer above the plane where the microlenses are located.

2 . The optical fingerprint device according to claim 1 , wherein a support structure is provided between the microlenses, at least one light-transmitting layer is provided above the support structure, and the surface of the light-transmitting layer is more than A light-blocking layer is arranged between the light-transmitting layers.

3 . The optical fingerprint device according to claim 2 , wherein the lowermost light-transmitting layer is bonded to the supporting structure. 4 .

4 . The optical fingerprint device according to claim 1 , wherein there is at least one light blocking layer below the plane where the microlenses are located. 5 .

5 . The optical fingerprint device according to claim 2 , wherein an infrared cut-off filter film is arranged on the surface of the light-transmitting layer or between multiple light-transmitting layers. 6 .

6 . The optical fingerprint device according to claim 5 , wherein at least one light blocking layer is disposed above the infrared cut filter film. 7 .

7 . The optical fingerprint device according to claim 1 , wherein there is at least one light-transmitting layer under the plane where the microlenses are located, and an infrared cutoff filter is provided on the surface of the light-transmitting layer or between the multiple light-transmitting layers. 8 . light film.

8 . The optical fingerprint device according to claim 7 , wherein a pad is provided around the pixel unit, and the pad is exposed by cutting and removing the light-transmitting layer. 9 .

9 . The optical fingerprint device of claim 1 , wherein an inner lens is provided on the surface of the pixel unit. 10 .

10 . The optical fingerprint device according to claim 1 or 4 , wherein the openings formed by the light blocking layer for light to pass through gradually decrease from top to bottom. 11 .

11. The optical fingerprint device according to claim 2 or 7, wherein the light-transmitting layer comprises glass, organic dry film or light-transmitting glue.

12 . The optical fingerprint device of claim 2 , wherein the refractive index of the light-transmitting layer close to the microlens is smaller than the refractive index of the light-transmitting layer far from the microlens and the refractive index of the microlens. 13 .

13. The optical fingerprint device of claim 1, wherein each microlens corresponds to one or more pixel units.