CN110737136A

CN110737136A - Backlight module and display device

Info

Publication number: CN110737136A
Application number: CN201911050477.XA
Authority: CN
Inventors: 黄阿海
Original assignee: Xiamen Tianma Microelectronics Co Ltd
Current assignee: Xiamen Tianma Microelectronics Co Ltd
Priority date: 2019-10-31
Filing date: 2019-10-31
Publication date: 2020-01-31
Anticipated expiration: 2039-10-31
Also published as: CN110737136B

Abstract

The invention discloses backlight modules and a display device, and relates to the technical field of display, wherein each backlight module comprises a fingerprint identification area and a non-fingerprint identification area, each backlight module also comprises a light guide plate, a plurality of grooves are arranged on the surface of the light guide plate side, the grooves are positioned on the light emitting surface of the light guide plate, each groove comprises a plurality of -th grooves positioned in the non-fingerprint identification area and a plurality of second grooves positioned in the fingerprint identification area, the -th grooves are linear grooves, and the second grooves are curved grooves.

Description

Backlight module and display device

Technical Field

The invention relates to the technical field of display, in particular to backlight modules and a display device.

Background

The fingerprint is a permanent feature that is unique and can be distinguished from other people, with the rapid development of display technology, display panels with fingerprint identification function have gradually spread throughout people's lives, and the fingerprint identification is applied to the display screens of electronic devices such as mobile phones, personal digital assistants, computers, and the like.

At present, the fingerprint identification technology is generally combined with the display technology, so that the display panel not only has the display function, but also can carry out fingerprint identification, thereby enriching the functions of the display panel, and simultaneously improving the safety performance of information in the display device. , the optical fingerprint identification technology is combined with the display technology, so that a fingerprint identification area is positioned in a display area, the problem of low screen occupation ratio of the display panel caused by the fact that the fingerprint identification area is arranged in a non-display area is solved, and the problem of poor experience caused by the fact that the fingerprint identification area is arranged on the back of the display panel is simultaneously avoided.

The important difficulties in applying optical fingerprint recognition to the display technology are that the light sensing unit is required to be disposed in the fingerprint recognition area of the display panel, so that the transmittance of the fingerprint recognition area in the display panel is inevitably reduced, and the luminance of the fingerprint recognition area is lower than that of the non-fingerprint recognition area, which affects the equal luminance of the display device.

Disclosure of Invention

In view of this, the invention provides backlight modules and display devices, which solve the problem in the prior art that the brightness of the fingerprint identification area is lower than that of the non-fingerprint identification area, and improve the uniformity of the brightness of the display device.

, the invention provides backlight modules, which include a fingerprint identification area and a non-fingerprint identification area, and further include a light guide plate, wherein the surface of the light guide plate side is provided with a plurality of grooves, the grooves are located on the light-emitting surface of the light guide plate, the grooves include a plurality of -th grooves located in the non-fingerprint identification area and a plurality of second grooves located in the fingerprint identification area, the -th grooves are linear grooves, and the second grooves are curved grooves.

In a second aspect, the invention provides kinds of display devices, which include a backlight module and a display panel located on a light-emitting surface of the backlight module, wherein the backlight module is the backlight module provided by the invention.

Compared with the prior art, the backlight module and the display device provided by the invention at least realize the following beneficial effects:

the backlight module comprises a light guide plate, wherein a plurality of grooves are arranged on the surface of the light guide plate, which is positioned on the side of the light-emitting surface, and the grooves comprise a plurality of -th grooves positioned in a non-fingerprint identification area and a plurality of second grooves positioned in a fingerprint identification area, wherein the -th grooves are linear grooves, the second grooves are curved grooves, and the lengths of the curved grooves are larger than those of the linear grooves in the same range, so that the light condensation effect of the curved grooves is better.

Of course, it is not necessary for any product embodying the invention to specifically achieve all of the above-described technical effects simultaneously.

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

Drawings

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

FIG. 1 is a schematic plan view of types of backlight modules provided by the present invention;

FIG. 2 is a cross-sectional view of the backlight module of FIG. 1 taken along line A-A' at ;

FIG. 3 is a schematic plan view of another kinds of backlight modules provided in the present invention;

FIG. 4 is a schematic plan view of another kinds of backlight modules provided by the present invention;

FIG. 5 is a cross-sectional view of the backlight module shown in FIG. 3 along B-B' at ;

FIG. 6 is another sectional views of the backlight module shown in FIG. 3 along B-B';

FIG. 7 is a cross-sectional view of the backlight module shown in FIG. 3 taken along line B-B' and taken along line ;

FIG. 8 is a cross-sectional view of the backlight module shown in FIG. 3 taken along line B-B' and taken along line ;

FIG. 9 is a schematic plan view of another kinds of backlight modules provided by the present invention;

FIG. 10 is a schematic structural diagram of types of backlight modules provided by the present invention;

FIG. 11 is a schematic plan view of a light guide plate in the backlight module shown in FIG. 10;

FIG. 12 is a schematic structural diagram of display devices provided by the present invention;

fig. 13 is a cross-sectional view of the display device of fig. 12 taken along C-C'.

Detailed Description

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

The following description of at least exemplary embodiments is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that like reference numerals and letters refer to like items in the following figures, and thus once a item is defined in figures, it need not be discussed further in in subsequent figures.

It should be noted that although the terms and 8652 may be used to describe the grooves in embodiments of the invention, these grooves should not be limited to these terms.

Fig. 1 is a schematic plan view of types of backlight modules provided by the present invention, fig. 2 is a types of cross-sectional views of the backlight module shown in fig. 1 along a-a', referring to fig. 1 and fig. 2, the present embodiment provides types of backlight modules, including a fingerprint identification area AA1 and a non-fingerprint identification area AA 2;

the backlight module further comprises a light guide plate 10, a plurality of grooves 11 are formed in the surface of the light guide plate 10 , the grooves 11 are located on the light emitting surface of the light guide plate 10, the grooves 11 comprise a plurality of -th grooves 12 located in the non-fingerprint identification area AA2 and a plurality of second grooves 13 located in the fingerprint identification area AA1, the -th grooves 12 are linear grooves, and the second grooves 13 are curved grooves.

First, it should be noted that, for a display device with a fingerprint identification function, the display device has a fingerprint identification area and a non-fingerprint identification area, in the embodiment of the present invention, the fingerprint identification area AA1 of the backlight module corresponds to the fingerprint identification area of the display device, and the non-fingerprint identification area AA2 of the backlight module corresponds to the non-fingerprint identification area of the display device.

Specifically, with continuing reference to fig. 1 and fig. 2, the backlight module provided in this embodiment includes a light guide plate 10, a plurality of grooves 11 are disposed on a surface of the light guide plate 10 located on the side of the light emitting surface, and the light transmitted inside the light guide plate 10 is refracted and reflected by the grooves 11, so as to change the transmission direction thereof, and the light is uniformly dispersed and emitted from the light emitting surface of the light guide plate 10.

Since the light transmitted inside the light guide plate 10 is refracted and reflected in the grooves 11, so that the grooves 11 have a light condensing effect, the grooves 11 include a plurality of -th grooves 12 located in the non-fingerprint identification area AA2 and a plurality of second grooves 13 located in the fingerprint identification area AA1, wherein the -th grooves 12 are linear grooves, the second grooves 13 are curved grooves, and the length of the curved grooves is greater than that of the linear grooves in the same range, so that the light condensing effect of the curved grooves is better, therefore, the plurality of second grooves 13 located in the fingerprint identification area AA1 are set as curved grooves, the number of light entering the display panel through the fingerprint identification area AA1 in the backlight module per unit area is increased, and is greater than the number of light entering the display panel through the non-fingerprint identification area AA2, and the increased number of light can compensate the portion of light shielded by the fingerprint sensor, so that the luminance of the display device in the fingerprint identification area and the non-fingerprint identification area tends to be the same, and the luminance uniformity of the display device is improved.

Fig. 3 is a schematic plan view of another kinds of backlight modules provided by the present invention, referring to fig. 3, wherein the second groove 13 is an annular groove.

Specifically, with reference to fig. 3, the plurality of second grooves 13 in the fingerprint identification area AA1 are annular grooves, and since the light transmitted inside the light guide plate 10 is refracted in the grooves 11, the light condensing effect of the annular grooves is better, therefore, the plurality of second grooves 13 in the fingerprint identification area AA1 are annular grooves, and further increases the quantity of light entering the display panel through the fingerprint identification area AA1 in the unit area of the backlight module, so that the quantity of light entering the display panel through the non-fingerprint identification area AA2 is greater than the quantity of light entering the display panel through the fingerprint identification area AA2, and the increased quantity of light can compensate the quantity of light blocked by the fingerprint sensor, so that the luminance of the display device in the fingerprint identification area and the non-fingerprint identification area tends to be the same, and the luminance of the display device is improved to be .

Because the line of fingerprint is close to being annular structure, a plurality of second slot 13 that are located fingerprint identification district AA1 set up to annular groove, and the shape of second slot 13 and the line of fingerprint are close to for the light path that refracts out via second slot 13 matches with the line of fingerprint, effectively alleviates the condition that light takes place to interfere the wadding in disorder when carrying out fingerprint identification, effectively promotes fingerprint identification's efficiency.

Optionally, a vertical projection of the second groove on the light emitting surface of the light guide plate is a circular ring structure or an elliptical ring structure.

Specifically, with reference to fig. 3, the vertical projection of the second groove 13 on the light-emitting surface of the light guide plate 10 is a circular ring structure, fig. 4 is a schematic plane structure of another types of backlight modules provided in the present invention, and with reference to fig. 4, the vertical projection of the second groove 13 on the light-emitting surface of the light guide plate 10 is an elliptical ring structure.

With reference to fig. 3, optionally, the center of the vertical projection of the second groove 13 on the light exit surface of the light guide plate 10 is located at the same point .

Specifically, with reference to fig. 3, the centers of the vertical projections of the second grooves 13 on the light-emitting surface of the light guide plate 10 are located at the same point , and the second grooves 13 are disposed based on the same point for the manufacturing process, so that the difficulty of the manufacturing process of the light guide plate is reduced, and the production cost is reduced.

With continued reference to fig. 3, optionally, wherein the second trenches 13 are equally spaced apart.

Specifically, with reference to fig. 3, because the light transmitted inside the light guide plate 10 is refracted and reflected in the grooves 11, the grooves 11 have a light condensing effect, the centers of the vertical projections of the second grooves 13 in the fingerprint identification area AA1 on the light exit surface of the light guide plate 10 are located at the same point , and the second grooves 13 are arranged at equal intervals, so that the amount of light incident on the display panel from each part in the fingerprint identification area AA1 in the backlight module is uniform, the light-emitting brightness of each part of the display device in the fingerprint identification area tends to be the same, and the light-emitting brightness uniformity of the display device is improved.

With continued reference to fig. 3, optionally, wherein the light guide plate 10 includes a edge 14 extending along the th direction X and a second edge 15 extending along the second direction Y, the th direction X intersects the second direction Y;

the th grooves 12 extend in the th direction X, and the th grooves 12 are aligned in the second direction Y.

Specifically, with continued reference to fig. 3, the th grooves 12 in the light guide plate 10 extend along the th direction X, and the th grooves 12 are arranged along the second direction Y, so that the light transmitted inside the light guide plate 10 is refracted and reflected by the th grooves 12, thereby changing the transmission direction thereof, and the light is uniformly scattered and emitted from the non-fingerprint identification area AA2 of the light guide plate 10.

It should be noted that, in this embodiment, the th trench 12 is exemplarily shown to extend along the th direction X, and the th trench 12 is arranged along the second direction Y, in other embodiments of the present invention, the th trench may also extend and be arranged along other directions, which is not described herein again.

FIG. 5 is a cross-sectional view of the backlight module shown in FIG. 3 taken along line B-B' of types, referring to FIGS. 3 and 5, wherein, alternatively, the width of the second grooves 13 is 10-30 μm, the depth of the second grooves 13 is 1-10 μm, and the distance between two adjacent second grooves 13 is 10-50 μm;

the th groove 12 has a groove width of 10-50 μm, the th groove 12 has a groove depth of 1-10 μm, and the spacing between two adjacent th grooves 12 is 10-50 μm.

Specifically, with continued reference to fig. 3 and 5, the groove width of the second groove 13 is d1, the groove depth of the second groove 13 is h1, and the distance between two adjacent -th grooves 12 is p1, wherein d1 is not less than 10 μm and not more than 30 μm, h1 is not less than 1 μm and not more than 10 μm, and p1 is not less than 10 μm and not more than 50 μm, while the process difficulty of the second groove 13 is not increased, light is effectively and uniformly dispersed from the fingerprint identification area AA1 of the light guide plate 10, the groove width of the -th groove 12 is d2, the groove depth of the -th groove 12 is h2, and the distance between two adjacent -th grooves 12 is p2, wherein d2 is not less than 10 μm and not more than 50 μm, h2 is not more than 10 μm and not more than p2 is not more than 50 μm, and the process difficulty of the -th groove 12 is not increased, and the light is effectively and not more than uniformly dispersed from the fingerprint identification area AA2 of the light guide plate 10.

It should be noted that, in the practical production engineering of the present invention, the groove width of the second groove 13, the groove depth of the second groove 13, and the distance between two adjacent second grooves 13 are exemplarily shown to be 10-30 μm, the groove width of the th groove 12 is 10-50 μm, the groove depth of the th groove 12 is 1-10 μm, and the distance between two adjacent th grooves 12 is 10-50 μm, and the groove width of the second groove 13, the groove depth of the second groove 13, the distance between two adjacent second grooves 13, the groove width of the th groove 12, the groove depth of the th groove 12, and the distance between two adjacent th grooves 12 can be set according to practical production requirements.

Optionally, the groove includes at least two th groove surfaces, and the th groove surface is a planar structure;

or the groove comprises at least second groove surfaces which are in arc surface structures.

Specifically, with continued reference to fig. 3 and 5, the groove 11 includes at least two th groove surfaces 111, and the th groove surface 111 is in a planar structure, fig. 6 is another cross-sectional view of the backlight module along the line B-B' shown in fig. 3, and with reference to fig. 3 and 6, the groove 11 includes at least second groove surfaces 112, and the second groove surfaces 112 are in an arc-shaped surface structure.

It should be noted that fig. 5 exemplarily shows that the grooves 11 each include two -th groove surfaces 111, fig. 6 exemplarily shows that the grooves 11 each include two second groove surfaces 112, in the present invention, the -th groove 12 and the second groove 13 may adopt different structures, fig. 7 exemplarily shows a cross-sectional view of the backlight module along B-B' of fig. 3 in another , referring to fig. 3 and fig. 7, the groove surface in the -th groove 12 is the -th groove surface 111 with a planar structure, and the groove surface in the second groove 13 is the second groove surface 112 with an arc-shaped surface structure, in other embodiments of the present invention, the -th groove 12 and the second groove 13 may be arranged according to actual production needs, and the present invention is not described herein.

Optionally, the groove is a V-shaped groove or a U-shaped groove.

Specifically, with reference to fig. 3 and 5, the groove 11 is a V-shaped groove, fig. 8 is another cross-sectional views of the backlight module along B-B' shown in fig. 3, and with reference to fig. 3 and 8, the groove 11 is a U-shaped groove.

Optionally, wherein the non-fingerprint identification region at least partially surrounds the fingerprint identification region.

In particular, with continued reference to FIG. 1, the non-fingerprinting area AA2 partially surrounds the fingerprinting area AA 1. With continued reference to FIG. 3, the non-fingerprint identification area AA2 surrounds the fingerprint identification area AA 1.

Fig. 9 is a schematic plan view of another kinds of backlight modules provided by the present invention, referring to fig. 9, wherein, optionally, the non-fingerprint identification area AA2 and the fingerprint identification area AA1 are arranged along the direction X.

It should be noted that, the fingerprint identification area AA1 of the backlight module corresponds to the fingerprint identification area of the display device, the non-fingerprint identification area AA2 of the backlight module corresponds to the non-fingerprint identification area of the display device, the setting of the fingerprint identification area AA1 and the non-fingerprint identification area AA2 of the backlight module can be set according to the fingerprint identification area and the non-fingerprint identification area of the display device, this embodiment exemplarily shows that the non-fingerprint identification area AA2 at least partially surrounds the fingerprint identification area AA1, or the non-fingerprint identification area AA2 and the fingerprint identification area AA1 are arranged along the -th direction X in the backlight module, in other embodiments of the present invention, the non-fingerprint identification area AA2 and the fingerprint identification area AA1 in the backlight module can also adopt other setting modes, which is not repeated by .

Fig. 10 is a schematic structural view of types of backlight modules provided by the present invention, fig. 11 is a schematic structural view of a plane of a light guide plate in the backlight module shown in fig. 10, referring to fig. 10 and fig. 11, optionally, wherein the backlight module further includes a light source 20, a reflective sheet 30, a diffusion sheet 40, and a brightness enhancement sheet 50;

the light guide plate 10 includes a edge 14 extending in an th direction X, and a second edge 15 extending in a second direction Y, the th direction X intersecting the second direction Y;

the light source 20 is located at the th edge 14 or the side of the second edge 15 of the light guide plate 10, the diffusion sheet 40 is located at the side of the light exit surface of the light guide plate 10, the brightness enhancement sheet 50 is located at the side of the diffusion sheet 40 far away from the light guide plate 10, and the reflection sheet 30 is located at the side of the light guide plate 20 far away from the diffusion sheet 40.

Specifically, with continuing reference to fig. 10 and 11, the backlight module provided in this embodiment further includes a light source 20, a reflective sheet 30, a diffusion sheet 40, and a brightness enhancement sheet 50, wherein the light source 20 is located at the th edge 14 or the side of the second edge 15 of the light guide plate 10, the light exit surface of the light source 20 can be opposite to the light entrance surface of the light guide plate 31, light guide points are disposed in the light guide plate 10, when incident light irradiates each light guide point on the light guide plate 10, the incident light is diffused toward each angle, the reflection condition is destroyed and the light exits from the light exit surface of the light guide plate 10, and meanwhile, the light transmitted inside the light guide plate 10 is refracted and reflected by the grooves 11, and the step changes the transmission direction of.

The reflective sheet 30 is located on the side of the light guide plate 20 away from the diffusion sheet 40, and the reflective sheet 30 is used for reflecting the light irradiated from the light source 20 to the bottom surface of the light guide plate 10 into the light guide plate 10.

The diffusion sheet 40 is located at the side of the light exit surface of the light guide plate 10, the diffusion sheet 40 may include two parts, i.e., a base material and scattering particles, the base material may be a material with high light transmittance, such as PET/PC/PMMA, etc., the scattering particles are dispersed in the base material, and when the light of the backlight passes through the diffusion sheet 40, the light repeatedly passes through two media with different refractive indexes, i.e., the base material and the scattering particles, and multiple refraction, reflection and scattering phenomena occur, thereby providing a uniform surface light source.

The brightness enhancement sheet 50 is located on the side of the diffusion sheet 40 away from the light guide plate 10, the brightness enhancement sheet 50 may be a prism sheet, a surface of the prism sheet has a micro-prism structure, light emitted from the backlight passes through the prism sheet, the micro-prism structure scatters the light, and the light is finally converged and emitted in the front view direction under the circulating action of the backlight system, so as to achieve the brightness enhancement effect.

The present embodiment provides display devices, including a backlight module and a display panel located on a light-emitting surface of the backlight module, wherein the backlight module is the backlight module as described above.

Please refer to fig. 12 and 13, fig. 12 is a schematic structural diagram of display devices provided by the present invention, fig. 13 is a cross-sectional view of the display device along D-D' in fig. 12 and 13, a display device 1000 provided in fig. 12 and 13 includes a backlight module 100 and a display panel 200 located on a light emitting surface of the backlight module 100, where the backlight module is the display panel 100 provided in any embodiment of the present invention, and the display device 1000 is described in fig. 12 and 13 by taking a mobile phone as an example only.

With continuing reference to fig. 12 and 13, optionally, wherein the display device 1000 includes a display area AA, the display area AA includes a fingerprint identification area AA 1';

the display device 1000 further comprises a plurality of fingerprint identification units 300 disposed in the fingerprint identification area AA 1'.

Specifically, the display device 1000 includes a display area AA, the display area AA includes a fingerprint identification area AA1 ', a fingerprint identification area AA1 of the backlight module 100 corresponds to a fingerprint identification area AA 1' of the display device 1000, the display device 1000 further includes a plurality of fingerprint identification units 300 disposed in the fingerprint identification area AA1 ', the fingerprint identification units 300 are configured to identify a fingerprint, a plurality of second grooves 13 disposed in the fingerprint identification area AA1 of the light guide plate 10 are configured as curved grooves, so that the number of light rays entering the display panel 200 through the fingerprint identification area AA1 in a unit area of the backlight module 100 is increased to be greater than the number of light rays entering the display panel through the non-fingerprint identification area AA2, and the increased number of light rays can compensate for the portion of light rays blocked by the fingerprint identification units 300, so that the light-emitting luminances of the display device 1000 in the fingerprint identification area AA1 and the non-fingerprint identification area AA 2' tend to be the same, and the luminance of the display device 1000 is improved in performance.

By the embodiment, the backlight module and the display device provided by the invention at least realize the following beneficial effects:

Although specific embodiments of the invention have been described in detail by way of example, it should be understood by those skilled in the art that the foregoing examples are for purposes of illustration only and are not intended to limit the scope of the invention.

Claims

1, kinds of backlight module, wherein include fingerprint identification district and non-fingerprint identification district;

backlight unit still includes the light guide plate, the surface of light guide plate side is equipped with a plurality of grooves, the groove is located the play plain noodles of light guide plate, the groove is including being located a plurality of grooves in non-fingerprint identification district and being located a plurality of second grooves in fingerprint identification district, the groove is the linear groove, the second groove is curved groove.

2. The backlight module according to claim 1,

the second groove is an annular groove.

3. The backlight module according to claim 2,

the vertical projection of the second groove on the light-emitting surface of the light guide plate is in a circular ring structure or an elliptical ring structure.

4. The backlight module according to claim 3,

the circle centers of the vertical projections of the second grooves on the light-emitting surface of the light guide plate are located at the same point .

5. The backlight module according to claim 4,

the second grooves are arranged at equal intervals.

6. The backlight module according to claim 5,

the light guide plate comprises a edge extending along an th direction, and a second edge extending along a second direction, the th direction intersecting the second direction;

the th grooves extend along the th direction, and the th grooves are aligned along the second direction.

7. The backlight module according to claim 6,

the groove width of the second grooves is 10-30 μm, the groove depth of the second grooves is 1-10 μm, and the distance between every two adjacent second grooves is 10-50 μm;

the groove width of the th groove is 10-50 μm, the groove depth of the th groove is 1-10 μm, and the distance between every two adjacent th grooves is 10-50 μm.

8. The backlight module according to claim 1,

the groove comprises at least two th groove surfaces, and the th groove surfaces are planar structures;

or the groove comprises at least second groove surfaces, and the second groove surfaces are of arc-shaped surface structures.

9. The backlight module according to claim 8,

the groove is a V-shaped groove or a U-shaped groove.

10. The backlight module according to claim 1,

the non-fingerprint identification region at least partially surrounds the fingerprint identification region.

11. The backlight module according to claim 1,

the non-fingerprint identification region and the fingerprint identification region are arranged along direction .

12. The backlight module as claimed in claim 1, further comprising a light source, a reflective sheet, a diffusion sheet and a brightness enhancement sheet;

the light source is located on the th edge or the side of the second edge of the light guide plate, the diffusion sheet is located on the side of the light-emitting surface of the light guide plate, the brightness enhancement sheet is located on the side of the diffusion sheet far away from the light guide plate, and the reflection sheet is located on the side of the light guide plate far away from the diffusion sheet.

A display device of , comprising:

a backlight module and a display panel located on a light-emitting surface of the backlight module, wherein the backlight module is the backlight module as claimed in any of claims 1-12.

14. The display device according to claim 13,

the display device comprises a display area, and the display area comprises the fingerprint identification area;

the display device also comprises a plurality of fingerprint identification units arranged in the fingerprint identification area.