CN114078261A - Fingerprint identification system, fingerprint acquisition equipment and electronic equipment - Google Patents

Abstract

The application relates to a fingerprint identification system, fingerprint collection equipment and electronic equipment, the fingerprint identification system includes: an optical waveguide layer; the first-level grating is arranged on the optical waveguide layer; the secondary grating is arranged on the optical waveguide layer, and the number of the secondary gratings is two or more; the diffracted light beams passing through the first-level grating can pass through the second-level grating, and the diffracted light beams passing through the second-level gratings are turned and at least partially crossed. In this embodiment, the waveguide light turns after passing through the secondary grating, thereby forming intercrossed waveguide light, the brightness of the light is high, thereby increasing the brightness of the light irradiated to the ridge of the finger, and the directions of the waveguide light are different after passing through the coupling of different secondary gratings, therefore, the intercrossed waveguide light can be irradiated to each position of the optical waveguide layer, and a dead angle of fingerprint irradiation is not easily formed, thereby improving the quality of a fingerprint image.

Description

Fingerprint identification system, fingerprint acquisition equipment and electronic equipment

Technical Field

The application relates to the technical field of electronic equipment, in particular to a fingerprint identification system, fingerprint acquisition equipment and electronic equipment.

Background

Electronic equipment such as a mobile phone becomes a main entrance for connecting a user with a digital world, but the rise of mobile payment prompts the user to pay more and more attention to mobile phone information security, and the traditional password and Pin code have the risk of being stolen, so that the requirement of mobile phone information security cannot be met. The biometric technology is a technology for authentication by human features, including human biological features such as fingerprints, human faces, irises, veins, voiceprints and DNA, and has a very high security due to individual differences, and is widely used in mobile phones. At present, a biometric identification technology applied to a mobile phone is generally a fingerprint identification system, which includes a sensor to identify a fingerprint of a user, so as to unlock the mobile phone. However, the quality and brightness of the picture recognized by the sensor affect the sensitivity of the fingerprint recognition system, and poor user experience is caused when the sensitivity is not high.

Disclosure of Invention

The application provides a fingerprint identification system, fingerprint collection equipment and electronic equipment, and this fingerprint identification system's fingerprint image quality is higher, can realize the high-quality fingerprint image of large tracts of land promptly.

A first aspect of the present application provides a fingerprint identification system, comprising: an optical waveguide layer; the primary grating is arranged on the optical waveguide layer; the secondary gratings are arranged on the optical waveguide layer, and the number of the secondary gratings is two or more; the diffracted light beams passing through the first-order grating can pass through the second-order grating, and the diffracted light beams passing through the second-order gratings are diverted and at least partially crossed. In this embodiment, when light emitted from the light source passes through the first-level grating, incident light is coupled into ± 1-level two-beam diffracted light, the waveguide light turns after passing through the second-level grating, so as to form mutually crossed waveguide light, the crossed waveguide light forms a cross area, and since the light in the cross area is crossed and superposed, the brightness of light in the area is high, so as to increase the brightness of light irradiating the ridge of a finger, and the directions of the waveguide light after being coupled by different second-level gratings are different, so that the crossed waveguide light can irradiate each position of the optical waveguide layer, and a dead angle of fingerprint irradiation is not easily formed, thereby improving the quality of a fingerprint image, and the fingerprint identification system can realize a large-area high-quality fingerprint image, and further improve the sensitivity and accuracy of fingerprint identification.

In one possible design, the second-order grating includes a first second-order grating and a second-order grating, and the first second-order grating and the second-order grating are located on both sides of the first-order grating.

In one possible design, a first includedangle θ 1 is formed between the direction of the grating lines of the first-level grating and the direction of the grating lines of the first-level grating, and a second includedangle θ 2 is formed between the direction of the grating lines of the second-level grating and the direction of the grating lines of the first-level grating; wherein the first includedangle theta 1 and the second includedangle theta 2 are the same or different.

In one possible design, θ 1 is 30 ° ≦ θ 1 ≦ 70 °, and/or, 30 ° ≦ θ 2 ≦ 70 °. The first includedangle theta 1 and the second includedangle theta 2 are beneficial to realizing the intersection of the steering light beams, so that the brightness of the intersection area is increased.

In one possible design, the period of the first-order grating is T1, the period of the first second-order grating is T2, and the period of the second-order grating is T3; λ/Np < T1< λ, 0< T2< λ, 0< T3< λ where Np is the refractive index of the optical waveguide layer and λ is the wavelength of light. The period T1 of the primary grating, the period T2 of the first secondary grating and the period T3 of the second secondary grating satisfy the above-described relationship to facilitate crossing of the turned light beams, thereby increasing the brightness of the crossing region.

In one possible design, a mirror is disposed on a side of the secondary grating away from the primary grating, and a reflected light path thereof passes through the secondary grating, so that a light beam irradiated to the mirror can be reflected, thereby increasing the brightness of the light.

In one possible embodiment, a mirror is arranged on the side of the optical waveguide layer facing away from the light source. So that the light beam irradiated to the mirror can be reflected, thereby increasing the brightness of the light.

In one possible embodiment, the primary and secondary gratings are located on the side of the optical waveguide layer facing away from the light source, or the primary and secondary gratings are located on the side of the optical waveguide layer facing away from the light source.

In one possible design, the primary grating and the secondary grating are located inside the optical waveguide layer and near a side of the optical waveguide layer.

In one possible embodiment, the grating lines of the first-order grating are parallel to one side of the optical waveguide layer.

In one possible design, the optical waveguide layer is perpendicular to the light source.

In one possible design, the thickness of the optical waveguide layer is 0.1mm to 10 mm.

A second aspect of the present application provides a fingerprint identification system, comprising: an optical waveguide layer; a first-order grating; two or more secondary gratings; the primary grating and the secondary grating are arranged on an optical waveguide layer, and at least one part of the transmitted +/-1-order light beam or the reflected +/-1-order light beam passing through the primary grating passes through the secondary grating to form a transmitted steering light beam and/or a reflected steering light beam. In this embodiment, each diffraction beam can make full use of, improve the coupling efficiency of grating to improve the utilization ratio of light, reduce the light intensity loss, improve the light beam density in fingerprint identification area, improve fingerprint identification system's fingerprint identification efficiency and sensitivity.

In one possible embodiment, the primary grating and the secondary grating are arranged within the optical waveguide layer.

In one possible embodiment, the primary grating is located on a surface of the optical waveguide layer facing away from the light source, and a metal layer is provided on a side of the primary grating facing away from the light source.

In one possible embodiment, the primary grating is located inside the optical waveguide layer, or on the surface of the optical waveguide layer close to the light source, and a mirror is arranged on the side of the optical waveguide layer facing away from the light source.

In one possible design, a mirror is arranged on the side of the secondary grating remote from the primary grating. So that the light beam irradiated to the mirror can be reflected, thereby increasing the brightness of the light.

A third aspect of the present application provides a fingerprint acquisition apparatus comprising the fingerprint identification system described above.

A fourth aspect of the present application provides an electronic device, comprising: a housing; the fingerprint identification system is the above fingerprint identification system; the fingerprint identification system is arranged on the shell and used for forming a fingerprint identification area on the shell. When the fingerprint identification system set up in the back lid, this fingerprint identification system need not to occupy the space of screen to the screen that does not influence electronic equipment accounts for the ratio, and this fingerprint identification system also need not at the back lid trompil to guarantee the integrality of back lid.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Drawings

FIG. 1 is a schematic diagram of a fingerprint identification system distributed on a rear cover according to an embodiment of the present application;

FIG. 2 is a schematic diagram of the fingerprint identification system of FIG. 1 in a first embodiment;

FIG. 3 is a side view of the fingerprint identification system of FIG. 2;

FIG. 4 is a schematic illustration of the optical path of the optical waveguide layer;

FIG. 5 is a schematic diagram of the distribution of the first-order grating and the second-order grating in FIG. 2;

FIG. 6 is a schematic diagram of the fingerprint identification system of FIG. 1 in a second embodiment;

FIG. 7 is a schematic diagram of a first embodiment of the mirror of FIGS. 2 and 6 disposed in an optical waveguide layer;

FIG. 8 is a schematic diagram of a second embodiment of the mirror of FIGS. 2 and 6 disposed in an optical waveguide layer;

fig. 9 is a schematic structural view of a third embodiment of the reflection mirror of fig. 2 and 6 disposed in an optical waveguide layer.

Reference numerals:

1-fingerprint identification system; 11-optical waveguide layer, 111-first side, 112-second side, 113-upper surface, 114-lower surface;

12-first order grating; 13-two-level grating, 131-first two-level grating, 132-second two-level grating; 14-a mirror; 15-a sensor; 16-a light source;

2-back cover, 21-cross area, 22-fingerprint identification area.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and together with the description, serve to explain the principles of the application.

Detailed Description

For better understanding of the technical solutions of the present application, the following detailed descriptions of the embodiments of the present application are provided with reference to the accompanying drawings.

It should be clear that the described embodiments are only a few embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In one embodiment, the present application is described in further detail below with reference to specific embodiments and accompanying drawings.

The fingerprint identification system in the prior art comprises an optical waveguide and a grating, when a light source irradiates the grating, incident light is diffracted under the effect of the grating and enters the optical waveguide to be reflected in the optical waveguide, and meanwhile, the period of the grating, the width of the grating and the thickness of a waveguide layer are controlled to enable the incident light not to be overlapped on an optical waveguide surface and spliced seamlessly, so that the fingerprint identification of the whole surface is formed.

However, since the grating is elongated and the length of the light source determines the width of the fingerprint recognition surface, the length of the light source needs to be increased, that is, a linear light source needs to be used in order to increase the width of the fingerprint recognition surface, and the linear light source has a high cost, which leads to a high cost of the fingerprint recognition system. In addition, after the incident light enters the waveguide layer, the identification light is in the same direction in the waveguide layer, so that the position where the identification light cannot irradiate exists, a fingerprint identification dead angle exists, namely the quality of a fingerprint image identified by the fingerprint identification system is poor, and the identification accuracy and the sensitivity of the fingerprint identification system are reduced.

In order to solve the technical problem, an embodiment of the present application provides a fingerprint image collecting device, an electronic device, and afingerprint identification system 1 thereof, where the fingerprint image collecting device may be a Charge Coupled Device (CCD), a Complementary Metal Oxide Semiconductor (CMOS), a Thin Film Transistor (TFT), and the CCD image sensor, the TFT, and the CMOS can be used in electronic devices such as a camera and a computer.

The electronic device may be a camera, a mobile phone, a tablet computer, a desktop computer, a laptop computer, a handheld computer, a notebook computer, an ultra-mobile personal computer (UMPC), a netbook, a cellular phone, a Personal Digital Assistant (PDA), an Augmented Reality (AR) device, a Virtual Reality (VR) device, an Artificial Intelligence (AI) device, a wearable device, a vehicle-mounted device, a smart home device, and/or a smart city device, and the specific type of the electronic device is not particularly limited in the embodiments of the present application.

The electronic device may include a screen module, a motherboard, a battery, a housing, and the like. Wherein, screen module, circuit board and battery all can be installed in the casing, and this casing can include the back lid, and along electronic equipment's thickness direction, the back lid sets up with the screen module relatively, and this back lid is used for supporting parts such as battery, circuit board to play the guard action to electronic equipment's each part.Fingerprint identification system 1 can set up in screen module below for the fingerprint identification of screen, as shown in fig. 3, thisfingerprint identification system 1 can also set up inhou gai 2 for the fingerprint identification ofback lid 2, when setting up inback lid 2, thisfingerprint identification system 1 need not to occupy the space of screen, thus does not influence electronic equipment's screen to account for than. The fingerprint recognition system is provided in therear cover 2 as an example.

In particular, as in the embodiment shown in fig. 2, thefingerprint recognition system 1 comprises: the grating structure comprises a light waveguide layer 11, a first-level grating 12 and a second-level grating 13, wherein the first-level grating 12 and the second-level grating 13 are both arranged on the light waveguide layer 11, the second-level grating 13 is two or more, and at least two second-level gratings 13 are positioned on two sides of the first-level grating 12. When the light source irradiates the first-order grating 12, the light beams diffracted by the first-order grating 12 can pass through each second-order grating 13, and the light beams diffracted by each second-order grating 13 at least partially intersect to form intersecting waveguide light, the intersecting waveguide light can be totally reflected in the optical waveguide layer 11, and the intersecting waveguide light forms anintersecting region 21. Meanwhile, as shown in fig. 5, thefingerprint recognition system 1 further includes asensor 15, and thesensor 15 is located below thecrossing area 21. When a user places a finger on theintersection area 21, the ridge of the finger contacts theback cover 2 to destroy the total reflection of the waveguide light in the optical waveguide layer 11, and the outgoing light beam illuminates the ridge of the finger and is transmitted to thesensor 15 below theintersection area 21 through diffuse reflection, so that fingerprint information is acquired.

In this embodiment, when light emitted from the light source passes through theprimary grating 12, incident light is coupled into ± 1 st two diffracted lights, the waveguide light turns after passing through thesecondary grating 13 to form mutually crossed waveguide light, the crossed waveguide light forms a crossedarea 21 on therear cover 2, and since the lights in the crossed area are crossed and overlapped, the brightness of light in the area is high, so as to increase the brightness of light irradiated to the ridge of a finger, and the directions of the waveguide light after being coupled through differentsecondary gratings 13 are different, so that the crossed waveguide light can be irradiated to each position of theoptical waveguide layer 1, and a dead angle of fingerprint irradiation is not easily formed, that is, the quality of a fingerprint image recognized by the fingerprint recognition system is higher, and a large-area high-quality fingerprint image can be realized, thereby improving the sensitivity and accuracy of fingerprint recognition.

As shown in fig. 1, thefingerprint recognition system 1 has arecognition area 22 formed on theback cover 2, the area of therecognition area 22 is larger than the area of theintersection area 21, and therecognition area 22 can be used for recognizing a fingerprint, but since light intersects theintersection area 21, the light intensity is high, and the quality of a recognized fingerprint image is high in theintersection area 21.

In one embodiment, as shown in fig. 1 and 2, thefingerprint recognition system 1 includes a first two-level grating 131 and a second two-level grating 132, and the first two-level grating 131 and the second two-level grating 132 are located at two sides of the first-level grating 12. Specifically, the twosecondary gratings 13 and theprimary grating 12 may be arranged along the length direction X of the electronic device, and the twosecondary gratings 13 are located on two sides of theprimary grating 12 along the length direction X of the electronic device. The grating lines of thefirst grating 12 are parallel to thefirst side surface 111 and thesecond side surface 112 of the optical waveguide layer 11, and meanwhile, a certain included angle is formed between the grating lines of the twosecond gratings 13 and the grating lines of thefirst grating 12, so that the ± 1 st order diffraction light of thefirst grating 12 is deflected by thesecond gratings 13, directed to the middle area of the optical waveguide layer 11 and crossed.

Specifically, as shown in fig. 2, the grating lines of the first-level grating 12 are parallel to a side surface of the optical waveguide layer 11, as shown in fig. 5, a first includedangle θ 1 is formed between the direction of the grating lines of the first-level grating 131 and the direction of the grating lines of the first-level grating 12, and a second includedangle θ 2 is formed between the direction of the grating lines of the second-level grating 132 and the direction of the grating lines of the first-level grating 12. The first includedangle θ 1 and the second includedangle θ 2 may be the same or different.

Meanwhile, the period of the first-level grating 12 is T1, the period of the first-level grating 131 is T2, and the period of the second-level grating 132 is T3, wherein T2 and T3 may be the same or different. By controlling theabove θ 1,θ 2, T1, T2, and T3, the light beams that are turned by thesecondary grating 13 can be made to intersect.

Specifically, referring to fig. 4, when light is incident on the grating surface, the grating may cause the light to generate diffraction phenomenon, and the diffraction light has multiple orders, mainly 0 order and ± 1 order.

In a specific embodiment, 30 ≦ 1 ≦ 70 °, and/or 30 ≦ 2 ≦ 70 °, λ ≦ 70 ≦ ≦ 4 ≦ lambda ≦ E ≦ 70 ≦ E_p<T1<λ，0<T2<λ，0<T3<Lambda is measured. Where Np is the refractive index of the optical waveguide layer 11 and λ is the wavelength of light. For example,θ 1 may be 30 °, 40 °, 50 °, or 70 °, etc., andθ 2 may be 30 °, 35 °, 50 °, 60 °, or 70 °, etc.

In this embodiment, when 1, 2, T1, T2, and T3 are within the above range, the two beams diffracted by the twosecondary gratings 13 intersect to form anintersection region 21.

In one embodiment, the dimensions of the optical waveguide layer 11 are: 65mm by 50mm by 5mm, i.e. the thickness of the optical waveguide layer 11 is 5 mm; the incident light source is 1 watt of total radiation power, the luminous flux is 604.43lumen, and the simulation can obtain: the average illuminance of incident light passing through the first-level grating 12 is 2400lux and the maximum illuminance is 3300lux, after the two second-level gratings 13 are optically crossed, the average illuminance of a longitudinal section simulated illuminance diagram of the crossedarea 21 is 450lux and the maximum illuminance is 603lux, and the average illuminance of a longitudinal section simulated illuminance diagram of theidentification area 22 of thefingerprint identification system 1 is 224lux and the maximum illuminance is 359 lux.

Compared with the fingerprint identification system without the intersection area in the prior art, thefingerprint identification system 1 in the embodiment of the application has the advantages that the average illumination of theintersection area 21 is 280lux, and the maximum illumination is 371 lux; in the prior art, the illuminance of the front non-overlapping area is 150lux on average and 236ux on the maximum, and the contrast can be obtained, thefingerprint identification system 1 in the embodiment of the present application can significantly improve the brightness of thefingerprint identification area 21, and the brightness is about twice of the brightness of the non-overlapping area, so that thefingerprint identification system 1 in the embodiment of the present application can significantly improve the quality of the identified fingerprint image.

In the above embodiments, as shown in fig. 3, thereflector 14 is disposed on the side of thesecondary grating 13 away from theprimary grating 12, that is, thereflector 14 is disposed on the opposite side of the light-emitting surface of thesecondary grating 13, at this time, after thereflector 14 is disposed, the light is reflected by thereflector 14, so as to enhance the intensity of the light emitted from thesecondary grating 13, further increase the intensity of the light in thefingerprint identification area 22, and improve the accuracy of thesensor 15 in identifying the fingerprint.

In this embodiment, the reflectingmirror 14 is disposed on thefirst side surface 111 and thesecond side surface 112 of the optical waveguide layer 11, thefirst side surface 111 and thesecond side surface 112 are disposed oppositely, thefirst side surface 111 is located on one side of the first-level grating 131 away from the first-level grating 12, thesecond side surface 112 is located on one side of the second-level grating 132 away from the first-level grating 12, and the reflectingmirror 14 is disposed on both thefirst side surface 111 and thesecond side surface 112, so that light rays irradiated to the two second-level gratings 13 can be reflected by the reflectingmirror 14, and the utilization rate of the light rays is improved.

As shown in fig. 2, the optical waveguide layer 11 further has anupper end surface 113 and alower end surface 114 disposed opposite to each other along the thickness direction Z, wherein thelower end surface 114 is an end surface close to thelight source 16, and theupper end surface 113 is an end surface far from thelight source 16. Thereflector 14 may be disposed on thelower end surface 114 of the optical waveguide layer 11 close to thelight source 16, or, when a plurality of optical waveguide layers 11 are included, a reflector may be disposed between two adjacent optical waveguide layers 11, or a metal layer may be deposited on the grating, and in this case, the metal layer functions as a reflector, that is, the metal layer can function as a light reflector.

As shown in fig. 3, areflector 14 is disposed on the side of the optical waveguide layer 11 away from thelight source 16, that is, areflector 14 is disposed on theupper end surface 113 of the optical waveguide layer 11, thereflector 14 may be formed by depositing a metal layer, and thereflector 14 can reflect light into the optical waveguide layer 11, thereby improving the utilization rate of light.

In addition, in thefingerprint identification system 1, the reflectingmirror 14 may be disposed on each of thefirst side surface 111, thesecond side surface 112 and theupper end surface 113 of the optical waveguide layer 11, so as to further improve the brightness of thefingerprint identification area 22 in fig. 1, that is, improve the utilization rate of light, and further improve the fingerprint identification efficiency of thefingerprint identification system 1.

In a specific embodiment, as shown in fig. 2, theprimary grating 12 and thesecondary grating 13 are located on a side of the optical waveguide layer 11 away from thelight source 16, i.e. theprimary grating 12 and thesecondary grating 13 are both disposed on anupper end surface 113 of the optical waveguide layer 11, or theprimary grating 12 and thesecondary grating 13 may also be located on a side of the optical waveguide layer 11 close to thelight source 16, i.e. theprimary grating 12 and thesecondary grating 13 may also be both disposed on alower end surface 114 of the optical waveguide layer 11.

In another embodiment, theprimary grating 12 and thesecondary grating 13 may be located inside the optical waveguide layer 11 and near a side of the optical waveguide layer 11.

In the above embodiments, the optical waveguide layer 11 may be perpendicular to thelight source 16, that is, the light from thelight source 16 is incident perpendicularly to the first-order grating 12, but the optical waveguide layer 11 may not be perpendicular to thelight source 16.

In the above embodiments, the thickness of the optical waveguide layer 11 may be 0.1mm to 10mm, and may be, for example, 0.1mm, 1mm, 2mm, 4mm, 5mm, 7mm, 10mm, or the like.

In another embodiment, as shown in fig. 6, thefingerprint recognition system 1 may include: the optical waveguide layer 11, the first-order grating 12, the second-order grating 13, this second-order grating 13 can be two or more, wherein, this first-order grating 12 and second-order grating 13 set up in the optical waveguide layer 11, the transmission + -1 level light beam or the reflection + -1 level light beam through the first-order grating 12 at least partly form the transmission through the second-order grating 13 and turn to the light beam and/or reflect and turn to the light beam, improve the coupling efficiency of grating, thereby improve the utilization ratio of light, reduce the light intensity loss, improve the beam density offingerprint identification region 22, improve the fingerprint identification efficiency offingerprint identification system 1.

Specifically, theprimary grating 12 and thesecondary grating 13 may be disposed on one side of the optical waveguide layer 11 facing thelight source 16, at this time, the transmitted light beam formed by thesecondary grating 13 may be fully utilized, and may also be disposed on one side of the optical waveguide layer 11 away from thelight source 16, at this time, the reflected light beam formed by thesecondary grating 13 may be fully utilized, and may also be disposed inside the optical waveguide layer 11, at this time, the transmitted light beam and the reflected light beam formed by thesecondary grating 13 may be fully utilized, thereby further improving the coupling efficiency of the gratings, thereby improving the utilization rate of light, reducing the light intensity loss, improving the light beam density of thefingerprint identification region 22, and improving the fingerprint identification efficiency of thefingerprint identification system 1.

Further, as shown in fig. 6 to 9, thefingerprint identification system 1 may further include areflector 14, thereflector 14 is disposed on one side of thesecondary grating 13 away from theprimary grating 12, that is, thereflector 14 is disposed on the opposite side of the light exit surface of thesecondary grating 13, at this time, after thereflector 14 is disposed, the light is reflected by thereflector 14, so as to improve the utilization rate of the light, further increase the intensity of the light in thefingerprint identification area 22, and improve the accuracy of fingerprint identification by thesensor 15.

In this embodiment, as shown in fig. 6, the reflectingmirror 14 is disposed on thefirst side surface 111 and thesecond side surface 112 of the optical waveguide layer 11, thefirst side surface 111 and thesecond side surface 112 are disposed oppositely, thefirst side surface 111 is located on one side of the first-order grating 131 away from the first-order grating 12, thesecond side surface 112 is located on one side of the second-order grating 132 away from the first-order grating 12, and the reflectingmirror 14 is disposed on both thefirst side surface 111 and thesecond side surface 112, so that light rays irradiated to the two second-order gratings 13 can be reflected by the reflectingmirror 14, and thus the utilization rate of the light rays is improved.

As described above, the use ratio of the light emitted from thesecondary grating 13 can be improved by providing themirror 14 of thesecondary grating 13.

Of course, the fingerprint recognition system may also be provided with amirror 14 of theprimary grating 12. Specifically, the optical waveguide layer 11 further has anupper end surface 113 and alower end surface 114 disposed opposite to each other in the thickness direction Z, wherein thelower end surface 114 is an end surface close to thelight source 16, and theupper end surface 113 is an end surface far from thelight source 16. When the first-order grating 12 is located on theupper end surface 113 of the optical waveguide layer 11, which is far away from the light source, theupper end surface 113 is provided with a metal layer, and at this time, the metal layer arranged on the first-order grating 12 can improve the diffraction efficiency of the first-order grating 12, so that the utilization rate of light emitted from the first-order grating 12 is improved. When theprimary grating 12 is located inside the optical waveguide layer 11, or theprimary grating 12 is located on thelower end surface 114 of the optical waveguide layer 11 close to the light source, thelower end surface 114 of the optical waveguide layer 11 is provided with thereflector 14, and at this time, thereflector 14 is located on the light exit surface of theprimary grating 12, so that the light emitted from theprimary grating 12 can be reflected, and the utilization rate of the light emitted from theprimary grating 12 can be improved.

In one embodiment, thefirst side 111, thesecond side 112, theupper end 113 and thelower end 114 of the optical waveguide layer 11 of thefingerprint identification system 1 can be provided with thereflector 14, so as to further improve the brightness of thefingerprint identification area 21 and further improve the fingerprint identification efficiency of thefingerprint identification system 1. Through comparison, thereflector 14 can make the light turn back completely, and the turned-back light still propagates in a total reflection mode; compared with the light intensity, the light intensity is more intense, namely the brightness is improved after thereflector 14 is added.

In a specific embodiment, after themirror 14 is added, the brightness of theprimary grating 12 is increased from 4900lux to 5100lux, and the brightness of thesecondary grating 13 is increased from 353lux to 428lux, so that after themirror 14 is added, the brightness of the emergent light can be effectively increased.

To sum up, in the embodiment of the present application, the sensitivity of fingerprint identification can be improved by the two schemes, the first scheme is: thesecondary grating 13 turns the light beams, so that the turned light beams are crossed, and the brightness of a crossed area is improved; and the second method comprises the following steps: the first-stage grating 12 and the second-stage grating 13 are disposed inside the optical waveguide layer 11, thereby improving the utilization rate of light beams and further improving brightness. Meanwhile, in both schemes, thereflector 14 can be additionally arranged, so that the brightness is further improved.

It is noted that a portion of this patent application contains material which is subject to copyright protection. The copyright owner reserves the copyright rights whatsoever, except for making copies of the patent files or recorded patent document contents of the patent office.

Claims (14)

1. A fingerprint identification system, the fingerprint identification system comprising:

an optical waveguide layer;

the primary grating is arranged on the optical waveguide layer;

the secondary gratings are arranged on the optical waveguide layer, and the number of the secondary gratings is two or more;

the diffracted light beams passing through the first-order grating can pass through the second-order grating, and the diffracted light beams passing through the second-order gratings are diverted and at least partially crossed.

2. The fingerprint recognition system of claim 1, wherein the two-level grating comprises a first two-level grating and a second two-level grating, and the first two-level grating and the second two-level grating are located on both sides of the first level grating.

3. The fingerprint identification system according to claim 2, wherein the direction of the grating lines of the first-level grating has a first angle θ 1 with the direction of the grating lines of the first-level grating, and the direction of the grating lines of the second-level grating has a second angle θ 2 with the direction of the grating lines of the first-level grating;

wherein the first included angle theta 1 and the second included angle theta 2 are the same or different.

4. The fingerprint recognition system of claim 3, wherein 30 ° ≦ θ 1 ≦ 70 °, and/or 30 ° ≦ θ 2 ≦ 70 °.

5. The fingerprint recognition system of claim 1, wherein the first-order grating has a period of T1, the first second-order grating has a period of T2, and the second-order grating has a period of T3;

λ/Np < T1< λ, 0< T2< λ, 0< T3< λ where Np is the refractive index of the optical waveguide layer and λ is the wavelength of light.

6. The fingerprint identification system of any one of claims 1-5, wherein a mirror is disposed on a side of the secondary grating away from the primary grating, and a reflected light path of the mirror passes through the secondary grating.

7. The fingerprint identification system of any one of claims 1-5, wherein a reflector is disposed on a side of the optical waveguide layer away from the light source.

8. A fingerprint identification system, the fingerprint identification system comprising:

an optical waveguide layer;

a first-order grating;

two or more secondary gratings;

the primary grating and the secondary grating are arranged on an optical waveguide layer, and at least one part of the transmitted +/-1-order light beam or the reflected +/-1-order light beam passing through the primary grating passes through the secondary grating to form a transmitted steering light beam and/or a reflected steering light beam.

9. The fingerprint identification system of claim 8, wherein the primary grating and the secondary grating are disposed within the optical waveguide layer.

10. The fingerprint identification system of claim 8, wherein the primary grating is located on a surface of the optical waveguide layer away from the light source, and a metal layer is disposed on a side of the primary grating away from the light source.

11. The fingerprint recognition system of claim 8, wherein the primary grating is located inside the optical waveguide layer, or is located on a surface of the optical waveguide layer close to the light source, and a reflector is arranged on a side of the optical waveguide layer far from the light source.

12. The fingerprint identification system of any one of claims 8-11, wherein a mirror is disposed on a side of the secondary grating away from the primary grating.

13. A fingerprint acquisition device, characterized in that the fingerprint acquisition device comprises a fingerprint identification system according to any one of claims 1 to 12.

14. An electronic device, characterized in that the electronic device comprises:

a housing;

a fingerprint identification system as claimed in any one of claims 1 to 12;

the fingerprint identification system is arranged on the shell and used for forming a fingerprint identification area on the shell.

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