Fingerprint recognition device and method for forming the same

Abstract

A fingerprint recognition device and a method for forming the same, wherein the fingerprint recognition device comprises: a substrate; an infrared light source located on the substrate; an optical sensor located on the substrate and spaced apart from the infrared light source; a display screen, the display screen having a relative touch surface and a back surface, the display screen being located above the substrate, the back surface facing the substrate, the back surface comprising a covering area and an exposed area, the projection of the infrared light source toward the back surface being located within the covering area, the projection of the optical sensor toward the back surface being located within the exposed area; an internal reflection absorption sheet located on the back surface and covering the covering area, the internal reflection absorption sheet exposing the exposed area. The fingerprint recognition device helps improve the quality of fingerprint imaging.

Description

Technical Field

[0001] The present invention relates to the field of fingerprint recognition technology, and in particular to a fingerprint recognition device and a forming method thereof. Background Art

[0002] Fingerprint recognition devices can realize automatic fingerprint collection and are widely used in equipment such as attendance machines, access control systems, mobile phones or tablet computers.

[0003] According to the principle of fingerprint imaging, fingerprint recognition devices can be divided into optical fingerprint recognition devices, semiconductor capacitance recognition devices, semiconductor thermistor recognition devices, semiconductor pressure-sensitive recognition devices, etc.

[0004] Among them, the optical fingerprint recognition device mainly utilizes the principle of refraction and reflection of light. The light emitted by the light source is refracted at different angles on the uneven lines of the fingerprint on the surface of the finger, and the reflected light has different brightness. The optical sensor will correspondingly collect image information of different brightness levels, thereby completing the fingerprint collection.

[0005] Optical fingerprint recognition devices have strong environmental adaptability and good stability, and low production costs, so optical fingerprint recognition devices are widely used.

[0006] However, existing optical fingerprint recognition devices still need to be improved. Summary of the invention

[0007] The problem solved by the present invention is to provide a fingerprint identification device and a forming method thereof, which are helpful to improve the fingerprint imaging quality.

[0008] To solve the above problems, the present invention provides a fingerprint recognition device, comprising: a substrate; an infrared light source, located on the substrate; an optical sensor, located on the substrate and spaced apart from the infrared light source; a display screen, the display screen having a relative touch surface and a back surface, the display screen being located above the substrate, the back surface facing the substrate, the back surface comprising a covering area and an exposed area, the projection of the infrared light source toward the back surface being located within the covering area, and the projection of the optical sensor toward the back surface being located within the exposed area; an internal reflection absorption sheet, located on the back surface and covering the covering area, the internal reflection absorption sheet exposing the exposed area.

[0009] Optionally, the internal reflection absorption plate includes: a linear polarizer and a quarter wave plate located on the linear polarizer, and the quarter wave plate is located between the back surface and the linear polarizer.

[0010] Optionally, the angle between the optical axis direction of the quarter wave plate and the selection direction of the linear polarizer is 45°.

[0011] Optionally, the internal reflection absorption sheet further includes: an adhesive layer, wherein the adhesive layer is located between the linear polarizer and the quarter wave plate.

[0012] Optionally, the linear polarizer includes a core material layer, a first protective layer and a second protective layer, and the core material layer is located between the first protective layer and the second protective layer.

[0013] Optionally, the material of the core material layer is polyvinyl alcohol.

[0014] Optionally, the materials of the first protective layer and the second protective layer are both cellulose triacetate.

[0015] Optionally, the display screen includes: a display panel and a protective glass plate located on the display panel, the bottom surface of the display panel is the back surface, the top surface of the protective glass plate is the touch surface, and the display panel has a plurality of light-emitting units arranged at intervals.

[0016] Optionally, the display panel includes a lower substrate and an upper substrate, the light emitting unit is located between the lower substrate and the upper substrate, and the lower substrate and the upper substrate are both made of glass.

[0017] Optionally, it further includes: a light-shielding wall located on the substrate, wherein the light-shielding wall is located between the infrared light source and the optical sensor.

[0018] Optionally, the top of the light-shielding wall is higher than the top of the infrared light source, and the top of the light-shielding wall is higher than the top of the optical sensor.

[0019] Optionally, a projection of the light-shielding wall toward the back side is located within the coverage area.

[0020] Optionally, the surface of the light-shielding baffle wall is a black light-absorbing surface, and the internal material of the light-shielding baffle wall is foam, plastic or metal.

[0021] The present invention provides a method for forming the above-mentioned fingerprint recognition device, comprising: providing a substrate; forming an infrared light source on the substrate; forming an optical sensor on the substrate, wherein the optical sensor and the infrared light source are spaced apart; forming a display screen above the substrate, wherein the display screen has a relative touch surface and a back surface, wherein the back surface faces the substrate, wherein the back surface includes a covering area and an exposed area, wherein the projection of the infrared light source toward the back surface is located within the covering area, and the projection of the optical sensor toward the back surface is located within the exposed area; and forming an internal reflection absorption sheet on the back surface, wherein the internal reflection absorption sheet covers the covering area and the internal reflection absorption sheet exposes the exposed area.

[0022] Optionally, the internal reflection absorption plate includes: a linear polarizer and a 1 / 4 wave plate located on the linear polarizer; the steps of forming the internal reflection absorption plate include: providing a 1 / 4 wave plate; forming a linear polarizer on the 1 / 4 wave plate; adhering the 1 / 4 wave plate to the covering area on the back side, and the 1 / 4 wave plate is located between the back side and the linear polarizer.

[0023] Optionally, the internal reflection absorption plate also includes: an adhesive layer; after providing the 1 / 4 wave plate and before forming the linear polarizer, it also includes: forming an adhesive layer covering the 1 / 4 wave plate, and the adhesive layer is located between the linear polarizer and the 1 / 4 wave plate.

[0024] Optionally, the linear polarizer includes a core material layer, a first protective layer and a second protective layer, and the core material layer is located between the first protective layer and the second protective layer; wherein the steps of forming the core material layer include: providing a core material film; dyeing the core material film; extending the dyed core material film; dehydrating and drying the extended core material film to form the core material layer.

[0025] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0026] The display screen has a touch surface and a back surface opposite to each other, and the back surface includes a covering area and an exposed area. The projection of the infrared light source toward the back surface is located in the covering area. The internal reflection absorption sheet is located on the back surface and covers the covering area, and the initial infrared light emitted by the infrared light source is irradiated toward the display screen through the internal reflection absorption sheet. Part of the initial infrared light emitted by the infrared light source is directly reflected near the back surface to form interfering infrared reflected light. Another part of the initial infrared light emitted by the infrared light source is reflected at the touch surface to form effective infrared reflected light. The internal reflection absorption sheet can filter out the interfering infrared reflected light passing through the internal reflection absorption sheet, thereby reducing the amount of interfering infrared reflected light received by the optical sensor. The projection of the optical sensor toward the back surface is located in the exposed area, which is conducive to receiving the effective infrared reflected light whose light direction deviates from the internal reflection absorption sheet, avoiding the effective infrared reflected light being filtered out by the internal reflection absorption sheet and unable to be received by the optical sensor, thereby ensuring the receiving performance of the optical sensor for the effective infrared reflected light, and because the internal reflection absorption sheet can reduce the amount of interfering infrared reflected light received, the fingerprint imaging quality of the optical sensor can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic structural diagram of a fingerprint recognition device according to an embodiment of the present invention;

[0028] Figure 2 It is a schematic structural diagram of an internal reflection absorption sheet according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] Now, a fingerprint recognition device is analyzed, which includes an optical sensor and a display screen located above the optical sensor; the display screen has a touch surface and a back surface opposite to each other, and the back surface faces the optical sensor; the display screen has a plurality of light-emitting units arranged at intervals. When collecting fingerprints, when a finger presses the display screen, the light emitted by the light-emitting unit is reflected by the surface of the finger to form reflected light carrying fingerprint information, and the optical sensor receives the reflected light to form a fingerprint image.

[0030] When the light-emitting unit is used as an imaging light source, the startup time of the light-emitting unit is relatively long, resulting in a relatively long fingerprint collection time. In order to shorten the fingerprint collection time, an infrared light source can be added to the fingerprint recognition device as another imaging light source. However, part of the initial infrared light emitted by the infrared light source is reflected when it hits the light-emitting unit, and the interfering infrared reflected light directly enters the optical sensor, affecting the fingerprint imaging quality.

[0031] The inventor has studied the above-mentioned fingerprint recognition device. After creative work, the inventor has noticed that by attaching an internal reflection absorption sheet to the covering area of ​​the back side and making the projection of the infrared light source toward the back side located in the covering area, and the projection of the optical sensor toward the back side located in the exposed area, it helps to reduce the absorption of interfering infrared reflected light by the optical sensor and improve the fingerprint imaging quality.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0033] refer to Figure 1 A fingerprint recognition device 100 includes: a substrate 110, an infrared light source 200, an optical sensor 300, a display screen 400, and an internal reflection absorption sheet 500. The infrared light source 200 and the optical sensor 300 are both located on the substrate 110, and there is a gap between the infrared light source 200 and the optical sensor 300. The display screen 400 is located above the substrate 110, and the display screen 400 has a touch surface 401 and a back surface 402 opposite to each other, the back surface 402 faces the substrate 110, and the internal reflection absorption sheet 500 covers a portion of the back surface 402.

[0034] In this embodiment, the back surface 402 includes a covered area I and an exposed area II. The projection of the infrared light source 200 toward the back surface 402 is located in the covered area I. The projection of the optical sensor 300 toward the back surface 402 is located in the exposed area II.

[0035] The internal reflection absorption sheet 500 is located on the back surface 402 and covers the covering area I. The internal reflection absorption sheet 500 exposes the exposed area II.

[0036] The initial infrared light emitted by the infrared light source 200 is irradiated toward the display screen 400 through the internal reflection absorption sheet 500. Part of the initial infrared light emitted by the infrared light source 200 is directly reflected near the back surface 402 to form interfering infrared reflected light 702. Another part of the initial infrared light emitted by the infrared light source 200 is reflected at the touch surface 401 to form effective infrared reflected light 712. The interfering infrared reflected light 702 is the reflected light inside the display screen 400, which is a useless light signal, or even an interfering light signal or a harmful light signal. The effective infrared reflected light 712 is the reflected light at the contact interface between the finger and the screen, which is a useful light signal. This part of the light signal contains the texture information of the fingerprint.

[0037] The internal reflection absorption sheet 500 can filter out the interfering infrared reflected light 702 passing through the internal reflection absorption sheet 500 , thereby reducing the amount of the interfering infrared reflected light 702 received by the optical sensor 300 .

[0038] The projection of the optical sensor 300 toward the back side 402 is located within the exposure area II, which is conducive to receiving the effective infrared reflected light 712 whose direction deviates from the internal reflection absorption sheet 500, avoiding the effective infrared reflected light 712 from being filtered out by the internal reflection absorption sheet 500 and thus unable to be received by the optical sensor 300, thereby ensuring the receiving performance of the optical sensor 300 for the effective infrared reflected light 712. Since the internal reflection absorption sheet 500 can reduce the amount of interference infrared reflected light 702 received by the optical sensor 300, the fingerprint imaging quality of the optical sensor 300 can be significantly improved.

[0039] In this embodiment, the optical sensor 300 includes a CMOS optoelectronic chip and optical components such as a focusing lens located above the CMOS optoelectronic chip. The CMOS optoelectronic chip is used to absorb incident light to generate an image signal, and the optical components are used to focus the incident near-infrared light onto the photosensitive surface of the CMOS optoelectronic chip. The optical sensor 300 also includes a filter layer for absorbing or reflecting visible light and infrared light of wavelengths other than the infrared light wavelength emitted by the infrared light source 200, so as to prevent ambient light or light emitted by the display screen 400 from entering the optical sensor 300 through the display screen 400 and affecting fingerprint imaging.

[0040] In this embodiment, the display screen 400 includes: a display panel 410 and a protective glass plate 420 located on the display panel 410, the bottom surface of the display panel 410 is the back surface 402, the top surface of the protective glass plate 420 is the touch surface 401, and the display panel 410 has a plurality of light-emitting units 413 arranged at intervals.

[0041] In this embodiment, the light emitting unit 413 is used as an imaging light source. When collecting fingerprints, the finger presses the touch surface 401, and the light emitted by the light emitting unit 413 is reflected by the finger surface to form a first reflected light. Since the finger surface includes uneven ridges and valleys, the intensity of the first reflected light formed at the ridges and valleys is different, so the first reflected light carries fingerprint information. The first reflected light passes through the display screen 400 and is received by the optical sensor 300 to achieve fingerprint imaging.

[0042] In this embodiment, the infrared light source 200 is used as another imaging light source. When collecting fingerprints, the finger presses the touch surface 401, and the infrared light emitted by the infrared light source 200 is reflected by the finger surface to form a second reflected light, which carries fingerprint information. The second reflected light passes through the display screen 400 and is received by the optical sensor 300, which can also realize fingerprint imaging.

[0043] In this embodiment, the fingerprint recognition device 100 supports two imaging light sources, the light emitting unit 413 and the infrared light source 200, and is applicable to a wider range of scenarios. The infrared light source 200 is used as an imaging light source for fingerprint collection, which shortens the collection time and simplifies the process. When the infrared light source 200 fails, the light emitting unit 413 can be selected as an imaging light source to light up in the form of pixels to avoid delaying the fingerprint collection process.

[0044] In other embodiments, only the infrared light source 200 is used as an imaging light source. When collecting fingerprints, the finger presses the touch surface 401, and the infrared light emitted by the infrared light source 200 is reflected by the finger surface to form reflected light, and the reflected light carries fingerprint information. The reflected light passes through the display screen 400 and is received by the optical sensor 300 to achieve fingerprint imaging. In this solution, since only the infrared light source 200 is used as the imaging light source, not only the collection speed is faster, but also the infrared light flicker is not easily noticed by the user, and the user experience is better.

[0045] In this embodiment, the infrared light emitted by the infrared light source 200 is a narrow-band near-infrared light (band width is less than 100 nm) with a wavelength greater than 700 nm and less than 1200 nm. The purpose of using near-infrared light is to prevent the user from seeing the light emitted by the light source for fingerprint collection, so as to avoid affecting the display effect of the display screen 400. In addition, since the user cannot feel the light during the collection process, the user experience is better.

[0046] The wires and bottom electrodes of the light-emitting unit 413 are made of metal materials, which make the light-emitting unit 413 highly reflective. When the infrared light source 200 is selected as the imaging light source, if the initial infrared light emitted by the infrared light source 200 is irradiated on the light-emitting unit 413, it will be reflected, and the interference infrared reflected light 702 formed will directly enter the optical sensor 300, which will seriously affect the fingerprint imaging quality. To avoid this situation, the internal reflection absorption sheet 500 is covered on a part of the back surface 402.

[0047] The effective wavelength of the linear polarizer and the quarter wave plate includes the wavelength of the infrared light source. If the effective wavelength is only the narrow band near infrared light (band width less than 100nm) emitted by the infrared light source 200, it is simpler to manufacture and has lower cost.

[0048] The internal reflection absorption sheet 500 can filter out the interfering infrared reflected light 702 formed by the interfering initial infrared light 701 emitted by the infrared light source 200 and reflected on the light-emitting unit 413 .

[0049] In this embodiment, the internal reflection absorption sheet 500 includes: a linear polarizer 510 and a quarter wave plate 520 located on the linear polarizer 510 , and the quarter wave plate 520 is located between the back surface 402 and the linear polarizer 510 .

[0050] In this embodiment, the material of the linear polarizer 510 is organic. The material of the quarter wave plate 520 is also organic.

[0051] Below Figure 1 The function of the internal reflection absorption sheet 500 is described in detail by taking the traveling process of the initial infrared light 701 as an example.

[0052] The interfering initial infrared light 701 is selected by the linear polarizer 510 to form incident linear polarized infrared light. After the incident linear polarized infrared light passes through the 1 / 4 wave plate 520, a 1 / 4 wavelength phase difference is generated on two mutually perpendicular components to form incident circularly polarized infrared light. The incident circularly polarized infrared light is irradiated on the light-emitting unit 413 and reflected to form reflected circularly polarized infrared light. The reflected circularly polarized infrared light passes through the 1 / 4 wave plate 520, and a 1 / 4 wavelength phase difference is superimposed on the two components again, with a total phase difference of 1 / 2 wavelength, to form reflected linearly polarized infrared light. The polarization direction of the reflected linearly polarized infrared light is perpendicular to the selection direction of the linear polarizer 510, so the reflected linearly polarized infrared light cannot pass through the linear polarizer 510 and is filtered out.

[0053] The selection direction of the linear polarizer 510 is the polarization direction of the linear polarizer 510, that is, the polarization direction of linear polarized light formed after natural light passes through the linear polarizer 510. The linear polarizer 510 only allows light vibrating parallel to the polarization direction to pass through, and absorbs light vibrating perpendicular to the polarization direction.

[0054] In this embodiment, the angle between the optical axis direction of the quarter wave plate 520 and the selection direction of the linear polarizer 510 is 45°.

[0055] In this embodiment, the selection direction of the linear polarizer 510 is parallel to the horizontal plane, so the incident linearly polarized infrared light is horizontally polarized light.

[0056] In this embodiment, the incident circularly polarized infrared light is right-handed circularly polarized light, and the reflected circularly polarized infrared light is left-handed circularly polarized light.

[0057] In this embodiment, the reflected linearly polarized infrared light is vertically polarized light, and its polarization direction is along the vertical direction, and cannot pass through the linear polarizer 510 .

[0058] refer to Figure 2 The internal reflection absorption sheet 500 further includes: an adhesive layer 530 , and the adhesive layer 530 is located between the linear polarizer 510 and the quarter wave plate 520 . Figure 1 The glue layer is not shown.

[0059] The adhesive layer 530 can improve the adhesion strength between the linear polarizer 510 and the quarter wave plate 520 .

[0060] The linear polarizer 510 includes a core material layer 511 , a first protective layer 512 , and a second protective layer 513 . The core material layer 511 is located between the first protective layer 512 and the second protective layer 513 .

[0061] In this embodiment, the material of the core material layer 511 is a high molecular polymer. Specifically, the material of the core material layer 511 is polyvinyl alcohol.

[0062] The material of the core material layer 511 is polyvinyl alcohol, so that the core material layer 511 is hydrophilic. The first protective layer 512 and the second protective layer 513 can reduce the risk of deformation of the core material layer 511 in a hot and humid environment, prevent the core material layer 511 from shrinking or relaxing to affect the polarization performance, and also help to improve the strength of the core material layer 511, improve the problem of the core material layer 511 being brittle and easy to break, and facilitate the use and processing of the core material layer 511.

[0063] In this embodiment, the materials of the first protective layer 512 and the second protective layer 513 are both triacetyl cellulose. The triacetyl cellulose material has the advantages of high strength, high light transmittance and moisture and heat resistance. The first protective layer 512 and the second protective layer 513 made of triacetyl cellulose material can achieve the protection effect of the core material layer 511 and improve the moisture and heat resistance and strength of the formed 1 / 4 wave plate 520.

[0064] In other embodiments, one of the top surface or the bottom surface of the core material layer 511 may have a protective layer.

[0065] like Figure 1 As shown, part of the initial infrared light emitted by the infrared light source 200 passes through the gap between two adjacent light-emitting units 413 and irradiates toward the touch surface 401. The part of the initial infrared light is the effective initial infrared light 711.

[0066] The effective initial infrared light 711 is reflected by the finger surface at the touch surface 401 to form effective infrared reflected light 712. The effective infrared reflected light 712 can be used for fingerprint imaging after being absorbed by the optical sensor 300.

[0067] The projection of the infrared light source 200 toward the back side 402 is located in the coverage area I, while the projection of the optical sensor 300 toward the back side 402 is located in the exposure area II, which helps to increase the intensity of the effective infrared reflected light 712 received by the optical sensor 300 .

[0068] Specifically, the effective initial infrared light 711 will pass through the internal reflection absorption sheet 500 during the incident process. In order to ensure that the effective initial infrared light 711 smoothly enters the optical sensor 300, it is necessary to ensure that the effective infrared reflected light 712 will not pass through the internal reflection absorption sheet 500 during the traveling process, thereby avoiding the internal reflection absorption sheet 500 from filtering the effective infrared reflected light 712. The projection of the optical sensor 300 toward the back surface 402 is located in the exposure area II, which can increase the lateral offset distance between the effective infrared reflected light 712 and the effective initial infrared light 711, and reduce the risk of the effective infrared reflected light 712 passing through the internal reflection absorption sheet 500.

[0069] In this embodiment, the display panel 410 includes a lower substrate 411 and an upper substrate 412 . The light emitting unit 413 is located between the lower substrate 411 and the upper substrate 412 . The materials of the lower substrate 411 and the upper substrate 412 are both glass to avoid affecting the light path.

[0070] The fingerprint recognition device 100 further includes a light shielding wall 600 , wherein the light shielding wall 600 is located on the substrate 110 and between the infrared light source 200 and the optical sensor 300 .

[0071] The light shielding wall 600 can shield the edge initial infrared light 721 emitted by the infrared light source 200 whose light angle exceeds a predetermined threshold, so as to prevent the edge initial infrared light 721 from forming edge infrared reflected light after being reflected at the light emitting unit 413, thereby preventing the strong edge infrared reflected light from being received by the optical sensor 300 and affecting the fingerprint imaging quality. The light angle is the angle between the light direction and the vertical direction.

[0072] In this embodiment, the top of the light-shielding wall 600 is higher than the top of the infrared light source 200 , and the top of the light-shielding wall 600 is higher than the top of the optical sensor 300 , so as to ensure the shielding effect of the light-shielding wall 600 on the initial infrared light 721 at the edge.

[0073] In this embodiment, there is a distance between the light shielding wall 600 and the infrared light source 200, and there is also a distance between the light shielding wall 600 and the optical sensor 300. The infrared light source 200, the light shielding wall 600 and the optical sensor 300 are arranged separately on the substrate 110.

[0074] In this embodiment, the projection of the light-shielding wall 600 toward the back surface 402 is located within the coverage area I, and can shield the edge initial infrared light 721 that is directed toward the bottom edge of the internal reflection absorption sheet 500 .

[0075] In this embodiment, the surface of the light-shielding baffle wall 600 is a black rough light-absorbing surface, and the internal material of the light-shielding baffle wall 600 is foam, plastic or metal.

[0076] In this embodiment, there is an air gap between the internal reflection absorption sheet 500 and the light shielding wall 600 , between the internal reflection absorption sheet 500 and the infrared light source 200 , and between the back surface 402 and the optical sensor 300 .

[0077] Compared with using an adhesive layer to bond the internal reflection absorption sheet 500 to the light-shielding wall 600, the internal reflection absorption sheet 500 to the infrared light source 200, and the back side 402 to the optical sensor 300, retaining the air gap has little effect on the light path, and there is no need to consider the adhesive layer itself affecting the light path, or the bubbles or impurities contained in the adhesive layer affecting the light path.

[0078] In this embodiment, the covered area I and the exposed area II are only a part of the back side 402 of the display screen 400, and the back side 402 also includes other areas.

[0079] In some embodiments, other areas of the back side 402 except the covered area I and the exposed area II are covered with a shading layer to ensure that external light does not pass through the display screen 400 and then reflect back and then pass through the display screen 400, which helps to improve the contrast, uniformity and other performance of the display screen 400 and enhance the display effect of the display screen 400.

[0080] refer to Figure 1 The present invention also provides a method for forming the fingerprint recognition device 100, comprising: providing a substrate 110; forming an infrared light source 200 on the substrate 110; forming an optical sensor 300 on the substrate 110, wherein the optical sensor 300 is spaced apart from the infrared light source 200; forming a display screen 400 above the substrate 110, wherein the display screen 400 has a relative touch surface 401 and a back surface 402, wherein the back surface 402 faces the substrate 110, wherein the back surface 402 includes a covering area I and an exposed area II, wherein a projection of the infrared light source 200 toward the back surface 402 is located within the covering area I, and a projection of the optical sensor 300 toward the back surface 402 is located within the exposed area II; and forming an internal reflection absorption sheet 500 on the back surface 402, wherein the internal reflection absorption sheet 500 covers the covering area I, and the internal reflection absorption sheet 500 exposes the exposed area II.

[0081] refer to Figure 1 and Figure 2In this embodiment, the steps of forming the internal reflection absorption plate 500 include: providing a 1 / 4 wave plate 520; forming a linear polarizer 510 on the 1 / 4 wave plate 520; adhering the 1 / 4 wave plate 520 to the covering area I of the back side 402, and the 1 / 4 wave plate 520 is located between the back side 402 and the linear polarizer 510.

[0082] In this embodiment, the quarter wave plate 520 is bonded to the covering area I of the back surface 402 by transparent adhesive.

[0083] In this embodiment, before forming the linear polarizer 510 , the method further includes: forming an adhesive layer 530 covering the quarter wave plate 520 , wherein the adhesive layer 530 is located between the linear polarizer 510 and the quarter wave plate 520 .

[0084] The adhesive layer 530 can improve the adhesion strength between the linear polarizer 510 and the quarter wave plate 520 .

[0085] The linear polarizer 510 includes a core material layer 511 , a first protective layer 512 , and a second protective layer 513 . The core material layer 511 is located between the first protective layer 512 and the second protective layer 513 .

[0086] The method for forming the core material layer 511 includes: providing a core material film; dyeing the core material film with an organic dye having dichroic properties, and extending the core material film under certain humidity and temperature conditions so that the core material film absorbs the organic dye to form polarization properties; dehydrating and drying the extended core material film to form the core material layer 511.

[0087] In this embodiment, the material of the core material layer 511 is polyvinyl alcohol.

[0088] In this embodiment, the materials of the first protective layer 512 and the second protective layer 513 are both triacetyl cellulose.

[0089] The first protective layer 512 and the second protective layer 513 can reduce the risk of deformation of the core material layer 511 in a hot and humid environment and prevent the core material layer 511 from shrinking or relaxing.

[0090] In this embodiment, the forming method further includes: forming a light shielding wall 600 on the substrate 110 , wherein the light shielding wall 600 is located between the infrared light source 200 and the optical sensor 300 .

[0091] The light shielding wall 600 can shield the edge initial infrared light 721 emitted by the infrared light source 200 whose angle exceeds a predetermined threshold, thereby further improving the fingerprint imaging quality.

[0092] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A fingerprint recognition device, characterized in that: include: substrate; an infrared light source, located on the substrate; an optical sensor, located on the substrate and spaced apart from the infrared light source; A display screen, wherein the display screen has a touch surface and a back surface opposite to each other, the display screen is located above the substrate, the back surface faces the substrate, the back surface includes a cover area and an exposed area, the projection of the infrared light source toward the back surface is located in the cover area, and the projection of the optical sensor toward the back surface is located in the exposed area; An internal reflection absorption sheet, located on the back surface and covering the covering area, wherein the internal reflection absorption sheet exposes the exposed area; The initial infrared light emitted by the infrared light source is irradiated toward the display screen through the internal reflection absorption sheet; part of the initial infrared light emitted by the infrared light source is reflected near the back surface to form interfering infrared reflected light; the internal reflection absorption sheet is located in the optical path of the interfering infrared reflected light to filter out the interfering infrared reflected light.

2. The fingerprint recognition device according to claim 1, characterized in that: The internal reflection absorption sheet includes: a linear polarizer and a quarter wave plate located on the linear polarizer, and the quarter wave plate is located between the back surface and the linear polarizer.

3. The fingerprint recognition device according to claim 2, characterized in that: The angle between the optical axis direction of the quarter wave plate and the selection direction of the linear polarizer is 45°.

4. The fingerprint recognition device according to claim 2, characterized in that: The internal reflection absorption sheet further includes: an adhesive layer, and the adhesive layer is located between the linear polarizer and the quarter wave plate.

5. The fingerprint recognition device according to claim 2, characterized in that: The linear polarizer includes a core material layer, a first protective layer and a second protective layer, wherein the core material layer is located between the first protective layer and the second protective layer.

6. The fingerprint recognition device according to claim 5, characterized in that: The material of the core material layer is polyvinyl alcohol.

7. The fingerprint recognition device according to claim 5, characterized in that: The first protective layer and the second protective layer are both made of triacetyl cellulose.

8. The fingerprint recognition device according to claim 1, characterized in that: The display screen includes: a display panel and a protective glass plate located on the display panel, the bottom surface of the display panel is the back surface, the top surface of the protective glass plate is the touch surface, and the display panel has a plurality of light-emitting units arranged at intervals.

9. The fingerprint recognition device according to claim 8, characterized in that: The display panel includes a lower substrate and an upper substrate. The light emitting unit is located between the lower substrate and the upper substrate. The materials of the lower substrate and the upper substrate are both glass.

10. The fingerprint recognition device according to claim 1, characterized in that: Also includes: A light-shielding barrier is located on the substrate, and the light-shielding barrier is located between the infrared light source and the optical sensor.

11. The fingerprint recognition device according to claim 10, characterized in that: The top of the light-shielding wall is higher than the top of the infrared light source, and the top of the light-shielding wall is higher than the top of the optical sensor.

12. The fingerprint recognition device according to claim 10, characterized in that: The projection of the light-shielding wall toward the back side is located within the coverage area.

13. The fingerprint recognition device according to claim 10, characterized in that: The surface of the light-shielding baffle wall is a black light-absorbing surface, and the internal material of the light-shielding baffle wall is foam, plastic or metal.

14. A method for forming a fingerprint recognition device as claimed in claim 1, characterized in that: include: providing a substrate; forming an infrared light source on the substrate; forming an optical sensor on the substrate, wherein the optical sensor is spaced apart from the infrared light source; A display screen is formed on the substrate, wherein the display screen has a touch surface and a back surface facing each other, the back surface faces the substrate, the back surface includes a cover area and an exposed area, the projection of the infrared light source toward the back surface is located in the cover area, and the projection of the optical sensor toward the back surface is located in the exposed area; forming an internal reflection absorbing sheet on the back surface, wherein the internal reflection absorbing sheet covers the covering area and the internal reflection absorbing sheet exposes the exposed area; The initial infrared light emitted by the infrared light source is irradiated toward the display screen through the internal reflection absorption sheet; part of the initial infrared light emitted by the infrared light source is reflected near the back surface to form interfering infrared reflected light; the internal reflection absorption sheet is located in the optical path of the interfering infrared reflected light to filter out the interfering infrared reflected light.

15. The forming method according to claim 14, characterized in that: The internal reflection absorption sheet includes: a linear polarizer and a quarter wave plate located on the linear polarizer; The steps of forming the internal reflection absorption sheet include: Provide 1 / 4 wave plate; forming a linear polarizer on the quarter wave plate; The quarter wave plate is adhered to the cover area of ​​the back surface, and the quarter wave plate is located between the back surface and the linear polarizer.

16. The forming method according to claim 15, characterized in that: The internal reflection absorption sheet further comprises: a glue layer; After providing the 1 / 4 wave plate and before forming the linear polarizer, the method further includes: forming a glue layer covering the 1 / 4 wave plate, wherein the glue layer is located between the linear polarizer and the 1 / 4 wave plate.

17. The forming method according to claim 15, characterized in that: The linear polarizer comprises a core material layer, a first protective layer and a second protective layer, wherein the core material layer is located between the first protective layer and the second protective layer; Wherein, the step of forming the core material layer comprises: Providing core material membrane; dyeing the core material film; stretching the dyed core material film; The stretched core material film is dehydrated and dried to form the core material layer.

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