Optical fingerprint collector

Abstract

The disclosed embodiment provides an optical fingerprint collector, which includes: FPGA, backlight, sensor and optical fiber in sequence, wherein a filter layer is provided on the side of the sensor close to the optical fiber, and the wavelength transmitted by the filter layer is consistent with the wavelength of the backlight. The optical fingerprint collector of the disclosed embodiment sets the backlight after the sensor and the optical fiber, and the light emitted by the backlight reaches the optical fiber after passing through the sensor, and a rear filter layer is set on the sensor. When the filter layer receives the incident light from the outside, it only allows the light with the same wavelength as the backlight to enter the sensor. No matter how strong the external light is, the light from the outside that passes through the finger to reach the sensor does not affect the normal fingerprint collection of the sensor. The optical fingerprint collector is not limited to a certain working environment, and the collection result is more accurate.

Description

Technical Field

[0001] The present disclosure relates to the field of displays, and in particular to an optical fingerprint collector. Background Art

[0002] The uniqueness of fingerprints makes fingerprint imaging widely used. Fingerprint imaging recognition technology is widely used in fingerprint collection, smart devices, fingerprint locks and other fields. Optical fingerprint sensors are key components for fingerprint collection. They convert optical signals into electrical signals to realize fingerprint collection.

[0003] The optical fingerprint collector mainly realizes fingerprint collection through the light path. Since the optical fingerprint collector works outdoors, the strong light from the outside is a relatively large interference, resulting in inaccurate fingerprint collection results. Summary of the invention

[0004] In view of this, the embodiments of the present disclosure propose an optical fingerprint collector to solve the following problems in the prior art: the optical fingerprint collector mainly realizes fingerprint collection by optical path. Since the optical fingerprint collector works outdoors, strong external light is a relatively large interference, resulting in inaccurate fingerprint collection results.

[0005] On the one hand, an embodiment of the present disclosure proposes an optical fingerprint collector, which includes: FPGA, backlight, sensor and optical fiber in sequence, wherein a filter layer is provided on a side of the sensor close to the optical fiber, and the wavelength transmitted by the filter layer is consistent with the wavelength of the backlight.

[0006] In some embodiments, the filter layer includes: an absorptive cutoff film and a transparent OCA (Optically Clear Adhesive), wherein the absorptive cutoff film is provided on a side of the sensor close to the optical fiber, the absorptive cutoff film is connected to the optical fiber through the transparent OCA, and the wavelength transmitted by the absorptive cutoff film is consistent with the backlight wavelength.

[0007] In some embodiments, the filter layer is an OCA that transmits a predetermined wavelength, wherein the predetermined wavelength is consistent with the backlight wavelength.

[0008] In some embodiments, a high-hardness film is provided on a side of the optical fiber close to the finger being measured.

[0009] In some embodiments, the high hardness film is a reflective cut-off film, and a cut-off wavelength of the reflective cut-off film is consistent with a wavelength of the backlight.

[0010] In some embodiments, a high-transmittance anti-fingerprint film is disposed on the high-hardness film.

[0011] In some embodiments, the optical fiber includes: a fiber core, a fiber sheath, and an absorption filament, wherein the absorption filament is disposed in the fiber sheath to block adjacent fiber cores.

[0012] In some embodiments, the fiber core and the fiber skin satisfy at least one of the following conditions: the distance between the center points of adjacent fiber cores is less than a predetermined distance; the ratio of the diameter or radius of the fiber core to the fiber skin is greater than a predetermined ratio; the refractive index of the fiber core is greater than that of the fiber skin.

[0013] In some embodiments, the backlight includes, in sequence: a back panel, a reflector, an LED, a light guide plate, a prism, and an anti-peep film; or, a back panel, a reflector, an LED, a light guide plate, a prism, a PET film, and an anti-peep film, wherein the transmittance distribution of the entire surface of the PET film is opposite to the transmittance after passing through the light guide plate; or, the back panel, a direct-down LED, the light guide plate, and the anti-peep film.

[0014] In some embodiments, the FPGA includes: two groups of ROICs distributed on the non-detection area where the black plastic frame is located, the first group of ROICs and the second group of ROICs are arranged oppositely, and each ROIC in the first group of ROICs is arranged alternately with each ROIC in the second group of ROICs.

[0015] The optical fingerprint collector of the disclosed embodiment sets the backlight after the sensor and the optical fiber. The light emitted by the backlight passes through the sensor and then reaches the optical fiber. A rear filter layer is set on the sensor. When the filter layer receives external incident light, it only allows light with the same wavelength as the backlight to enter the sensor. No matter how strong the external light is, the light from the external light passing through the finger to reach the sensor will not affect the normal fingerprint collection of the sensor. The optical fingerprint collector is not limited to a certain working environment, and the collection result is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1 A schematic diagram of the structure of the optical fingerprint collector provided in the embodiment of the present disclosure Figure 1 ;

[0018] Figure 2 A schematic diagram of the configuration of the FPGA in the entire module provided by an embodiment of the present disclosure;

[0019] Figure 3A side view of the entire module with a housing added according to an embodiment of the present disclosure;

[0020] Figure 4 A schematic diagram of the structure of the optical fingerprint collector provided in the embodiment of the present disclosure Figure 2 ;

[0021] Figure 5 A schematic diagram of the structure of the optical fingerprint collector provided in the embodiment of the present disclosure Figure 3 ;

[0022] Figure 6 A schematic diagram of the structure of an optical fiber provided in an embodiment of the present disclosure;

[0023] Figure 7 A schematic diagram of LED arrangement of a first backlight provided in an embodiment of the present disclosure;

[0024] Figure 8 A schematic diagram of the structure of a first backlight provided in an embodiment of the present disclosure;

[0025] Fig. 9 A schematic diagram of the LED arrangement of the second backlight provided in the embodiment of the present disclosure Figure 2 .

[0026] Reference numerals:

[0027] 1-FPGA, 2-backlight, 3-sensor, 4-optical fiber, 5-high hardness film, 6-absorption cut-off film, 7-transparent OCA, 8-OCA that transmits a predetermined wavelength, 9-high-transmittance anti-fingerprint film, 10-filter layer, 41-fiber core, 42-fiber skin, 43-absorption wire, 21-backplane, 22-reflector, 23-LED, 24-light guide plate, 25-prism, 26-PET film, 27-anti-peep film, 28-direct-down LED. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0029] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0030] In order to keep the following description of the embodiments of the present disclosure clear and concise, the present disclosure omits detailed descriptions of well-known functions and well-known components.

[0031] The present disclosure provides an optical fingerprint collector, the structure of which is shown in FIG. Figure 1 As shown, it includes:

[0032] FPGA 1, backlight 2, sensor 3 and optical fiber 4, wherein a filter layer 10 is arranged on a side of the sensor 3 close to the optical fiber, and the wavelength transmitted by the filter layer is consistent with the wavelength of the backlight.

[0033] The optical fingerprint collector of the disclosed embodiment sets the backlight after the sensor and the optical fiber. The light emitted by the backlight passes through the sensor and then reaches the optical fiber. A rear filter layer is set on the sensor. When the filter layer receives external incident light, it only allows light with the same wavelength as the backlight to enter the sensor. No matter how strong the external light is, the light from the external light passing through the finger to reach the sensor will not affect the normal fingerprint collection of the sensor. The optical fingerprint collector is not limited to a certain working environment, and the collection result is more accurate.

[0034] A high-hard film 5 is provided on the side of the optical fiber 4 close to the finger to be tested. The high-hard film can be highly transparent and is only used to increase the surface hardness and ensure the passage of light. In order to further improve the accuracy of the optical fingerprint collector, the high-hard film 5 can also be a reflective cutoff film, and the wavelength cut off by the cutoff film is consistent with the backlight wavelength.

[0035] The above-mentioned FPGA is used to drive the sensor and backlight. The light generated by the backlight reaches the finger being tested through the optical fiber, and the sensor receives the light reflected by the finger being tested, thereby realizing fingerprint collection.

[0036] The optical fingerprint collector of the disclosed embodiment is composed of FPGA, backlight, sensor and optical fiber, wherein FPGA controls the ROIC (readout circuit) and Gate IC of the sensor to drive the sensor to work, and the backlight is also controlled by FPGA to output different light intensities. When the backlight is on, the light source passes through the sensor to reach the finger, and the light reflected by the finger enters the sensor, thereby realizing the recognition of the valley ridges of the fingerprint.

[0037] In specific implementation, the two groups of ROICs of the FPGA in the embodiment of the present disclosure are distributed in the non-detection area where the black plastic frame is located. The first group of ROICs and the second group of ROICs are arranged opposite to each other, and each ROIC in the first group of ROICs is arranged alternately with each ROIC in the second group of ROICs. The arrangement of the FPGA in the entire module is shown in the figure below. Figure 2 As shown in the figure, the middle area is the detection area with a resolution of 1600×1500, and there are 3 ROIC COFs (Chip On Film) on the top and bottom. The function of ROIC is to read data. They are placed on the top and bottom sides and are staggered to achieve equal resistance wiring to achieve signal uniformity; the first ROIC on the top reads the signals of columns 1-256, the second one on the bottom reads the signals of columns 276-512, and the second one on the top reads the signals of columns 512-758. In turn, 6 ROICs are used to read the signals of all columns. The connection between ROIC and the pixel is a metal connection of Mo / AL, and the connection distance is greater than 5.11mm; on the left are two Gate ICs and one FPC (Flexible Printed Circuit), one of which controls the switch of the pixel row, and the FPC is connected to the Gate IC through metal wires to control the Gate IC (two GateICs and FPC can be designed as gate IC COF). The FPC and ROIC are connected to the FPGA, and the pixel array is turned on and off through the signal output by the FPGA to read the pixel signal. The surrounding area is covered with black glue and adhered to the shell. Figure 3 As shown, the middle area (also called the AA area) is in an open window state, which ensures that the AA area receives signals and prevents interference from surrounding light. Figure 2 The side view of the entire module after adding the shell is as follows Figure 3 As shown, from bottom to top, it is composed of FPGA 1, backlight 2, sensor 3 and optical fiber 4, and there is a black frame glue (i.e. Figure 2 The black frame glue around the module is attached to the shell. The thickness of the entire module is between 3-7mm. The minimum design size of the sensor is 91.5mm×90.2mm; the minimum size of the entire module is 92.1mm×90.8mm. The size can be increased according to actual conditions without affecting portability.

[0038] The optical fingerprint collector provided with the reflective cut-off film can reflect effective light and improve the contrast. When implemented, the film material of the reflective cut-off film is a diamond-like material, such as SiO 2 Combined with SiC, the overall hardness can reach 9H, achieving scratch resistance.

[0039] Since fingers need to touch the surface repeatedly, fingerprint residue will affect the collection of fingerprints, so a high-transmittance anti-fingerprint film 9 (also called AF film) is coated on the outermost layer, that is, a high-transmittance anti-fingerprint film is set on the reflective cutoff film to prevent fingerprint residue.

[0040] As a preferred embodiment, the filter layer 10 includes an absorption cut-off film 6 and a transparent OCA 7. Figure 4 As shown, in this embodiment, an absorption cutoff film 6 is provided (i.e., coated) on the side of the sensor close to the optical fiber, and the absorption cutoff film 6 is connected to the optical fiber 4 through a transparent OCA 7, wherein the wavelength transmitted by the absorption cutoff film 6 is consistent with the backlight wavelength. In this embodiment, it is preferred that the blue light part is transmitted and the other part is cut off, and the cutoff wavelength transmittance is less than 3%. The absorption cutoff film can use blue resin or blue ink. In this embodiment, there is no clear limitation on the material, as long as the transmittance meets the requirements; transparent OCA is used to bond the optical fiber above the absorption cutoff film, and the transparent OCA has a transmittance greater than 90% and a thickness less than 25μm.

[0041] like Figure 5 As shown, as an alternative solution, the filter layer can be set to OCA8 that can transmit a predetermined wavelength, that is, an OCA that can transmit a predetermined wavelength is set on the side of the sensor close to the optical fiber, wherein the predetermined wavelength is consistent with the backlight wavelength. This alternative solution does not change the optical path of fingerprint collection. The backlight reaches the optical fiber, reaches the finger through total reflection of the optical fiber, and reaches the sensor again after being reflected by the finger. The coating on the optical fiber increases this part of the reflection, thereby increasing the contrast of the fingerprint.

[0042] Compared with backlight, sunlight is a greater interference factor. Therefore, the sensor's ability to resist strong external light is also particularly important. In strong light conditions, the light from the sunlight passing through the finger is absorbed by the absorption cutoff film or the OCA of a specific wavelength, so the strong light passing through the finger cannot reach the sensor, while this part of the optical fiber of the backlight will not be absorbed by the absorption cutoff film or the OCA of a specific wavelength, and will not affect the reception of effective signals.

[0043] Because fingers directly contact the optical fingerprint collector, it is also easy to generate static electricity, so the ability to prevent ESD is one of the important capabilities of the optical fingerprint collector. Figure 6As shown, it is a schematic diagram of the structure of the optical fiber of the embodiment of the present disclosure, the optical fiber 4 includes a core 41, a fiber sheath 42 and an absorption filament 43, wherein the absorption filament 43 is arranged in the fiber sheath 42 to block the adjacent core 41, and the proportion of the absorption filament is adjusted according to the actual application. Of course, the optical fiber structure recorded in the embodiment of the present invention takes the optimal structure as an example, and those skilled in the art can choose an existing optical fiber including only a core 41 and a fiber sheath 42 when setting, which is not limited here.

[0044] Among them, the pitch of the optical fiber (i.e., the distance from the core to the adjacent core or the distance from the fiber skin to the adjacent fiber skin) is less than 6μm, the diameter or radius ratio of the core and the fiber skin is greater than 0.8, and the refractive index of the core is greater than that of the fiber skin, so as to ensure that enough light is fully reflected in the core and passes through the optical fiber. The role of the absorption filament is to prevent crosstalk of the light passing through the fiber skin. The transmittance of the absorption filament in the visible light band of 300-800nm ​​is less than 1%. The absorption filament can be inserted by filling, replacement, or filling + replacement. Due to fingerprint recognition, the finger needs to repeatedly touch the surface, so the ESD requirements are very high. The fiber thickness is preferably 0.6-1.5mm. This thickness range can significantly improve the ESD capability of the device and meet the needs of fingerprint recognition.

[0045] As for the backlight 2, it can be a common backlight, that is, it includes a back plate 21, a reflector 22, an LED 23, a light guide plate 24, a prism 25, and an anti-peep film 27 in sequence. In order to ensure the uniformity of the backlight, the embodiment of the present disclosure adopts the following multiple ways to achieve it.

[0046] The first backlight 2 includes a back plate 21, a reflector 22, an LED 23, a light guide plate 24, a prism 25, a PET film 26, and an anti-peep film 27. This method is a common backlight + PET film method. The backlight structure is shown in FIG. Figure 7 and Figure 8 As shown, the LEDs are located on one side (or multiple sides) of the backlight, such as Figure 7 As shown in FIG. 1 , the LED is located on one side, and the point light source is converted into a surface light source through the light guide plate. Figure 8 As shown in the figure, it is the stacking result of the backlight. The back plate is the substrate of the backlight, and the reflector on the top reflects the scattered light of the LED below to the light guide plate. The light guide plate has a sparse and dense setting. Ideally, the line light source is converted into a uniform surface light source. However, in reality, the edge is too bright because a PET film with a specific transmittance is designed on the top. The transmittance distribution of the entire PET film is exactly opposite to the transmittance after passing through the light guide plate, thereby achieving the effect of reducing the strong light in the area and realizing the uniformity of the entire surface. The position of the PET film can be placed between the anti-peep film and the light guide plate. Figure 8Only one feasible solution is shown, that is, placing it under the privacy film, and those skilled in the art can adjust it according to needs. The function of the prism is to converge the divergence angle of the backlight and play a collimating role. The privacy film further plays a collimating role, and the angle of the transmitted light is ±30°.

[0047] The above solution is a solution for ordinary backlight to achieve uniformity requirements; Fig. 9 As shown, in order to better achieve the uniformity requirement, the embodiment of the present disclosure also provides a second backlight 2, that is, a mini LED or OLED direct-type solution can be used. The second backlight 2 includes a back panel 21, a direct-type LED 28, a light guide plate 24, and an anti-peep film 27. Since the backlight is a direct-type LED, the entire backlight surface is illuminated, and the uniformity of the backlight is higher. Fig. 9 As shown in the figure, the mini LED solution is shown. The mini LED design takes into account the requirements of image uniformity and uses Mini LED backlight. The size of the mini LED is 91.5mm×90.2mm, which matches the sensor size. As the sensor size is adjusted, the backlight size can also be adjusted accordingly. The backlight is evenly distributed in 13 rows and 12 columns, and the number of mini LEDs can be increased to improve the uniformity of the backlight. At the same time, mini LED uses partition control, which makes it easier to achieve uniformity across the entire surface.

[0048] In addition, although exemplary embodiments have been described herein, the scope includes any and all embodiments based on the present disclosure with equivalent elements, modifications, omissions, combinations (e.g., various embodiments intersecting schemes), adaptations or changes. The elements in the claims will be interpreted broadly based on the language adopted in the claims, and are not limited to the examples described in this specification or during the implementation of this application, and the examples will be interpreted as non-exclusive. Therefore, this specification and examples are intended to be considered as examples only, and the true scope and spirit are indicated by the following claims and the full scope of their equivalents.

[0049] The above description is intended to be illustrative rather than restrictive. For example, the above examples (or one or more of them) can be used in combination with each other. For example, a person of ordinary skill in the art can use other embodiments when reading the above description. In addition, in the above-mentioned specific embodiments, various features can be grouped together to simplify the present disclosure. This should not be interpreted as an intention that a disclosed feature that is not required to be protected is necessary for any claim. On the contrary, the subject matter of the present disclosure may be less than all the features of a specific disclosed embodiment. Thus, the following claims are incorporated into the specific embodiments as examples or embodiments, wherein each claim is independently used as a separate embodiment, and it is considered that these embodiments can be combined with each other in various combinations or arrangements. The scope of the present disclosure should be determined with reference to the attached claims and the full scope of equivalent forms granted by these claims.

[0050] Multiple embodiments of the present disclosure are described in detail above, but the present disclosure is not limited to these specific embodiments. Those skilled in the art can make various variations and modifications to the embodiments based on the concepts of the present disclosure, and these variations and modifications should all fall within the scope of protection required by the present disclosure.

Claims

1. An optical fingerprint collector, It is characterized in that Including in order: FPGA, backlight, sensor and optical fiber, wherein a filter layer is arranged on a side of the sensor close to the optical fiber, the wavelength transmitted by the filter layer is consistent with the wavelength of the backlight, the FPGA regulates the backlight to output different light intensities, the light generated by the backlight passes through the optical fiber to reach the finger being tested, and the sensor receives the light reflected by the finger being tested to realize fingerprint collection.

2. The optical fingerprint collector according to claim 1, It is characterized in that The filter layer comprises: An absorption type cutoff film and a transparent OCA, wherein the absorption type cutoff film is arranged on a side of the sensor close to the optical fiber, the absorption type cutoff film is connected to the optical fiber through the transparent OCA, and the wavelength transmitted by the absorption type cutoff film is consistent with the backlight wavelength.

3. The optical fingerprint collector according to claim 1, It is characterized in that The filter layer is an OCA that transmits a predetermined wavelength, wherein the predetermined wavelength is consistent with the backlight wavelength.

4. The optical fingerprint collector according to claim 1, It is characterized in that A high-hardness film is arranged on the side of the optical fiber close to the finger to be measured.

5. The optical fingerprint collector as claimed in claim 4, It is characterized in that The high hardness film is a reflective cut-off film, and the cut-off wavelength of the reflective cut-off film is consistent with the backlight wavelength.

6. The optical fingerprint collector as claimed in claim 4, It is characterized in that A high-transmittance anti-fingerprint film is arranged on the high-hardness film.

7. The optical fingerprint collector according to any one of claims 1 to 6, It is characterized in that The optical fiber comprises: A fiber core, a fiber sheath and an absorbing filament, wherein the absorbing filament is arranged in the fiber sheath to block adjacent fiber cores.

8. The optical fingerprint collector as claimed in claim 7, It is characterized in that The fiber core and the fiber sheath satisfy at least one of the following conditions: The distance between the center points of adjacent fiber cores is less than a predetermined distance; the ratio of the diameter or radius of the fiber core to the fiber skin is greater than a predetermined ratio; and the refractive index of the fiber core is greater than that of the fiber skin.

9. The optical fingerprint collector according to claim 1, It is characterized in that The backlight comprises in sequence: Back panel, reflector, LED, light guide, prism, privacy film; or, The back plate, the reflector, the LED, the light guide plate, the prism, the PET film, the privacy film, wherein the transmittance distribution of the entire surface of the PET film is opposite to the transmittance after passing through the light guide plate; or, The back panel, the direct-type LED, the light guide plate, and the anti-peep film.

10. The optical fingerprint collector according to claim 1, The characteristic is that FPGA include: Two groups of ROICs are distributed on the non-detection area where the black plastic frame is located. The first group of ROICs and the second group of ROICs are arranged opposite to each other, and each ROIC in the first group of ROICs is arranged alternately with each ROIC in the second group of ROICs.

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