WO2021077368A1

WO2021077368A1 - Fingerprint recognition apparatus and electronic device

Info

Publication number: WO2021077368A1
Application number: PCT/CN2019/113066
Authority: WO
Inventors: 高攀; 郭益平; 吴宝全
Original assignee: 深圳市汇顶科技股份有限公司
Priority date: 2019-10-24
Filing date: 2019-10-24
Publication date: 2021-04-29
Also published as: CN111095278B; CN111095278A

Abstract

Disclosed in the embodiments of the present application are a fingerprint recognition apparatus and an electronic device. The thickness of the fingerprint recognition apparatus can be reduced. The fingerprint recognition apparatus is appliable to an electronic device having a display screen. The fingerprint recognition apparatus is disposed below the display screen. The fingerprint recognition apparatus comprises: a micro-lens array, the surface of the micro-lens array being covered with an optical adhesive layer, and the optical adhesive layer being used for bonding the micro-lens array and the display screen; and a sensor chip used for receiving an optical signal returned by a finger above the display screen and converged by the micro-lens array, and generating a fingerprint image of the finger according to the optical signal.

Description

Fingerprint identification device and electronic equipment

Technical field

The embodiments of the present application relate to the field of fingerprint identification, and more specifically, to a fingerprint identification device and electronic equipment.

Background technique

With the rapid development of the mobile phone industry, fingerprint recognition technology has attracted more and more attention, and the practical application of fingerprint recognition technology under the screen has become a popular demand. The most widely used in the under-screen fingerprint recognition technology is the under-screen optical fingerprint recognition technology. The under-screen optical fingerprint recognition technology can use the light emitted by the screen as the light source. The light emitted by the screen will carry the fingerprint information of the finger after it shines on the finger above the screen. The light signal carrying fingerprint information will be received by the sensor chip for fingerprint identification.

However, people currently have higher and higher requirements for the thickness of electronic equipment. Since the thickness of the fingerprint identification device will affect the thickness of the electronic equipment, how to reduce the thickness of the fingerprint identification device has become an urgent problem to be solved.

Summary of the invention

The embodiments of the present application provide a fingerprint identification device and electronic equipment, which can reduce the thickness of the fingerprint identification device.

In a first aspect, a fingerprint identification device is provided, which is suitable for electronic equipment with a display screen, the fingerprint identification device is configured to be arranged below the display screen, and the fingerprint identification device includes: a microlens array, the The surface of the micro lens array is covered with an optical glue layer, the optical glue layer is used to bond the micro lens array and the display screen; the sensor chip is used to receive the return of the finger above the display screen and pass the The microlens array condenses the optical signal, and generates the fingerprint image of the finger according to the optical signal.

In the technical solution provided by the embodiments of the present application, the surface of the microlens array is covered with an optical glue layer to bond the microlens array to the display screen, which can improve the thermal expansion and contraction of the microlens array. In addition, the fingerprint identification device with this connection structure can achieve the purpose of reducing the thickness of the fingerprint identification device by reducing the thickness of the optical adhesive layer. The smaller the thickness of the optical adhesive layer, the smaller the thickness of the fingerprint identification device, as long as the arrangement of the optical adhesive layer can ensure that the optical adhesive layer can firmly adhere the microlens array to the display screen.

In some possible implementation manners, the optical glue layer is arranged so that there is no air gap between the microlens array and the display screen.

The arrangement of the optical glue layer can ensure the uniformity of the refractive index of the medium between the microlens array and the display screen, can simplify the design of the optical elements under the microlens array, and make the matching between the microlens array and other optical elements easy .

In some possible implementations, the optical adhesive layer includes a first optical adhesive layer and a second optical adhesive layer, the first optical adhesive layer covers the surface of the microlens array, and the second optical adhesive layer It is arranged above the first optical glue layer and used to bond the microlens array and the display screen, and the refractive index of the first optical glue layer is smaller than the refractive index of the microlenses in the microlens array.

In some possible implementations, the surface of the first optical adhesive layer that is in contact with the second optical adhesive layer is flat.

The upper surface of the first optical adhesive layer is kept flat, which is beneficial to improve the bonding strength of the second optical adhesive layer.

In some possible implementations, the refractive index of the first optical adhesive layer is lower than the refractive index of the second optical adhesive layer.

In some possible implementation manners, the refractive index of the first optical adhesive layer is less than 1.4.

In some possible implementations, the refractive index of the first optical adhesive layer is 1.1 or 1.2.

The smaller the refractive index of the first optical adhesive layer, the closer to the refractive index of air, the more difficult it is to match each optical element in the fingerprint identification device with the optical adhesive layer, and the simpler the design of the optical fingerprint identification device will be.

In some possible implementation manners, the thickness of the first optical glue layer is greater than the thickness of the microlens array. In this way, it can be ensured that the first optical adhesive layer completely covers the microlens array, which is beneficial to realize a flat surface of the microlens array.

In some possible implementation manners, the thickness of the first optical glue layer is 1-2 μm larger than the thickness of the microlens array.

In some possible implementation manners, the thickness of the first optical adhesive layer is 5-10 μm.

In some possible implementations, the transmittance of the first optical adhesive layer to optical signals in the visible light band is greater than 80%, and/or the transmittance of the second optical adhesive layer to optical signals in the visible light band More than 90%.

Setting a certain light transmittance for the first optical adhesive layer and the second optical adhesive layer can ensure that enough light signals enter the sensor chip and improve the fingerprint detection performance.

In some possible implementation manners, the thickness of the second optical adhesive layer is greater than 10 μm.

In some possible implementations, the second optical adhesive layer is an optically transparent adhesive layer OCA.

In some possible implementations, the coverage area of the optical glue layer is larger than the area of the microlens array.

In some possible implementation manners, the coverage area of the optical adhesive layer is equal to the area of the sensor chip.

In some possible implementation manners, the optical adhesive layer is flush with the side surface of the sensor chip up and down.

In some possible implementation manners, the fingerprint identification device further includes a circuit board, and the sensor chip is electrically connected to the circuit board by wire bonding or through silicon vias.

In some possible implementation manners, the fingerprint identification device includes an optical path layer disposed under the microlens array and used for guiding the optical signals passing through the microlens array to the sensor chip.

In some possible implementations, the light path layer includes a light blocking layer, and a small hole array is provided on the light blocking layer, and the small hole array is used to guide the optical signal passing through the microlens array to the sensor chip. .

In some possible implementation manners, the optical path layer includes a filter layer, and the filter layer is used to filter out optical signals of a specific wavelength band.

In some possible implementations, the filter layer is used to filter out infrared and/or red light waveband optical signals.

In some possible implementations, the filter layer is plated on the upper surface of the sensor chip.

In a second aspect, an electronic device is provided, including: a display screen, and the fingerprint identification device in the first aspect and any one of its possible implementation manners.

Description of the drawings

Fig. 1 is a schematic structural diagram of an electronic device used in an embodiment of the present application.

Fig. 2 is a schematic diagram of another structure of an electronic device used in an embodiment of the present application.

Fig. 3 is a schematic structural diagram of a traditional fingerprint identification device connected by frame stickers.

Fig. 4 is a schematic structural diagram of a fingerprint identification device provided by an embodiment of the present application.

Fig. 5 is a schematic structural diagram of another fingerprint identification device provided by an embodiment of the present application.

Fig. 6 is a schematic structural diagram of another fingerprint identification device provided by an embodiment of the present application.

FIG. 7 is a schematic structural diagram of another fingerprint identification device provided by an embodiment of the present application.

Fig. 8 is a schematic structural diagram of another fingerprint identification device provided by an embodiment of the present application.

Fig. 9 is a schematic structural diagram of another fingerprint identification device provided by an embodiment of the present application.

FIG. 10 is a schematic block diagram of an electronic device according to an embodiment of the present application.

Detailed ways

The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings.

With the development of the times and the advancement of technology, the screen ratio of electronic products has become higher and higher, and full screens have become the development trend of many electronic products. In order to adapt to the development trend of this kind of full screen, the photosensitive devices in electronic products such as fingerprint recognition and front camera will also be placed under the screen. The most widely used under-screen fingerprint identification technology is under-screen optical fingerprint identification technology. Due to the particularity of the under-screen optical fingerprint device, it is required that the light with fingerprint signal can be transmitted through the screen to the fingerprint sensor below to obtain the fingerprint signal.

Take the under-screen optical fingerprint recognition as an example to describe the fingerprint recognition process in detail.

It should be understood that the embodiments of this application can be applied to optical fingerprint systems, including but not limited to optical fingerprint recognition systems and medical diagnostic products based on optical fingerprint imaging. The embodiments of the application constitute any limitation, and the embodiments of the application are also applicable to other systems using optical imaging technology.

As a common application scenario, the optical fingerprint system provided in the embodiments of this application can be applied to portable or mobile computing devices such as smart phones, tablet computers, and gaming devices, as well as electronic databases, automobiles, and automated teller machines (ATMs) in banks. ) And other electronic equipment, but the embodiments of this application are not limited to this. The embodiments of this application can be applied to other mobile terminals or other electronic equipment with a display screen; more specifically, in the above electronic equipment, the fingerprint identification device can be Specifically, it is an optical fingerprint device, which can be arranged in a partial area or all of the area under the display screen to form an under-display optical fingerprint system. Alternatively, the fingerprint identification device can also be partially or fully integrated into the display screen of the electronic device to form an in-display optical fingerprint system.

FIG. 1 and FIG. 2 show two schematic structural diagrams of electronic devices to which the embodiments of this application can be applied. FIG. 1 is a top view, and FIG. 2 is a side view. The electronic device 10 includes a display screen 120 and an optical fingerprint device 130, wherein the optical fingerprint device 130 is arranged in a partial area below the display screen 120. The optical fingerprint device 130 includes an optical fingerprint sensor, and the optical fingerprint sensor includes a sensing array 133 having a plurality of optical sensing units 131, and the area where the sensing array is located or its sensing area is the fingerprint detection area 103 corresponding to the optical fingerprint device 130. As shown in FIG. 1, the fingerprint detection area 103 is located in the display area of the display screen 120. In an alternative embodiment, the optical fingerprint device 130 can also be arranged in other positions, such as the side of the display screen 120 or the non-transmissive area at the edge of the electronic device 10, and the light path design of the display screen 120 At least part of the optical signal of the display area is guided to the optical fingerprint device 130, so that the fingerprint detection area 103 is actually located in the display area of the display screen 120.

It should be understood that the area of the fingerprint detection area 103 may be different from the area of the sensing array of the optical fingerprint device 130. For example, through the optical path design of lens imaging, the reflective folding optical path design, or other optical path design such as light convergence or reflection, it can make The area of the fingerprint detection area 103 corresponding to the optical fingerprint device 130 is larger than the area of the sensing array of the optical fingerprint device 130. In other alternative implementations, if for example, light collimation is used for light path guidance, the fingerprint detection area 103 corresponding to the optical fingerprint device 130 may also be designed to be substantially the same as the area of the sensing array of the optical fingerprint device 130.

Therefore, when the user needs to unlock the electronic device or perform other fingerprint verification, he only needs to press his finger on the fingerprint detection area 103 located on the display screen 120 to realize fingerprint input. Since fingerprint detection can be implemented in the screen, the electronic device 10 adopting the above structure does not need to reserve space on the front side to set the fingerprint button (such as the Home button), so that a full-screen solution can be adopted, that is, the display area of the display screen 120 can be It basically extends to the front of the entire electronic device 10.

As an optional implementation, as shown in FIG. 2, the optical fingerprint device 130 includes a light detecting portion 134 and an optical component 132, the light detecting portion 134 includes a sensing array and a reading circuit electrically connected to the sensing array And other auxiliary circuits, which can be fabricated on a chip (Die) by semiconductor technology, such as an optical imaging chip or an optical fingerprint sensor. The sensing array is specifically a photodetector array, which includes a plurality of arrays distributed in an array. The photodetector can be used as the above-mentioned optical sensing unit; the optical component 132 can be arranged above the sensing array of the light detecting part 134, and it can specifically include a filter layer, a light guide layer or The optical path guiding structure and other optical elements, the filter layer can be used to filter out the ambient light penetrating the finger, and the light guiding layer or the optical path guiding structure is mainly used to guide the light returned from the finger to the sensing array. Optical inspection.

In terms of specific implementation, the optical assembly 132 and the light detecting part 134 may be packaged in the same optical fingerprint component. For example, the optical component 132 and the optical detection part 134 can be packaged in the same optical fingerprint chip, or the optical component 132 can be arranged outside the chip where the optical detection part 134 is located, for example, the optical component 132 can be attached to the Above the chip, or part of the components of the optical assembly 132 are integrated into the above-mentioned chip.

Among them, the light guide layer or light path guiding structure of the optical component 132 has multiple implementation schemes. For example, the light guide layer of the optical component 132 may specifically be a collimator layer made on a semiconductor silicon wafer. It has a plurality of collimating units or micro-hole arrays. The collimating unit can be specifically a small hole. Among the reflected light reflected from the finger, the light that is perpendicularly incident on the collimating unit can pass through and be sensed by the optics below it. The unit receives, and the light whose incident angle is too large is attenuated by multiple reflections inside the collimator unit. Therefore, each optical sensor unit can basically only receive the reflected light reflected by the fingerprint pattern directly above it. The array can detect the fingerprint image of the finger.

In another embodiment, the light guide layer or the light path guide structure may also be an optical lens (Lens) layer, which has one or more lens units, such as a lens group composed of one or more aspheric lenses. The component 132 may include a lens for condensing the reflected light reflected from the finger to the sensing array of the light detecting portion 134 below it, so that the sensing array can perform imaging based on the reflected light, thereby obtaining the fingerprint of the finger image. Optionally, the optical lens layer may further have a pinhole formed in the optical path of the lens unit, and the pinhole may cooperate with the optical lens layer to expand the field of view of the optical fingerprint device, so as to improve the fingerprint imaging of the optical fingerprint device 130 effect.

In other embodiments, the light guide layer or the light path guide structure may also specifically adopt a micro-lens (Micro-Lens) layer. The micro-lens layer has a micro-lens array formed by a plurality of micro-lens, which may be obtained through a semiconductor growth process or Other processes are formed above the sensing array of the light detection part 134, and each microlens may correspond to one of the sensing units of the sensing array. In addition, other optical film layers may be formed between the microlens layer and the sensing unit, such as a dielectric layer or a passivation layer. More specifically, a barrier with microholes may also be formed between the microlens layer and the sensing unit. Optical layer, wherein the microhole is formed between the corresponding microlens and the sensing unit, the light blocking layer can block the optical interference between the adjacent microlens and the sensing unit, and allow the light corresponding to the sensing unit to pass through the The micro lens is converged into the micro hole and is transmitted to the sensing unit through the micro hole to perform optical fingerprint imaging. It should be understood that several implementation solutions of the above-mentioned light path guiding structure can be used alone or in combination. For example, a microlens layer can be further provided under the collimator layer or the optical lens layer. Of course, when the collimator layer or the optical lens layer is used in combination with the microlens layer, the specific laminated structure or optical path may need to be adjusted according to actual needs.

Optionally, in some embodiments, the optical fingerprint device 130 may include only one optical fingerprint sensor. At this time, the fingerprint detection area 103 of the optical fingerprint device 130 has a small area and a fixed position. Therefore, when the user performs fingerprint input It is necessary to press the finger to a specific position of the fingerprint detection area 103, otherwise the optical fingerprint device 130 may not be able to collect fingerprint images, resulting in poor user experience.

In other alternative embodiments, the optical fingerprint device 130 may specifically include a plurality of optical fingerprint sensors; the plurality of optical fingerprint sensors may be arranged side by side under the display screen 120 in a splicing manner, and the sensing of the plurality of optical fingerprint sensors The areas collectively constitute the fingerprint detection area 103 corresponding to the optical fingerprint device 130. In other words, the fingerprint detection area 103 corresponding to the optical fingerprint device 130 may include multiple sub-areas, and each sub-area corresponds to the sensing area of one of the optical fingerprint sensors, so that the fingerprint collection area 103 of the optical fingerprint module 130 It can be extended to the main area of the lower half of the display screen, that is, to the area where the finger is habitually pressed, so as to realize the blind fingerprint input operation. Alternatively, when the number of optical fingerprint sensors is sufficient, the fingerprint detection area 130 can also be extended to half of the display area or even the entire display area, thereby realizing half-screen or full-screen fingerprint detection.

It should be understood that, in specific implementation, the electronic device 10 further includes a transparent cover 110, or referred to as a transparent protective cover 110, the cover 110 may be a glass cover or a sapphire cover, which is located on the display screen 120 And cover the front of the electronic device 10. Because, in the embodiment of the present application, the so-called finger pressing on the display screen 120 actually refers to pressing the cover 110 above the display 120 or covering the surface of the protective layer of the cover 110.

It should be understood that the display screen 120 in the embodiment of the present application may adopt a display screen with a self-luminous display unit, such as an organic light-emitting diode (Organic Light-Emitting Diode, OLED) display screen or a micro-LED (Micro-LED) display screen . Taking the OLED display screen as an example, the optical fingerprint device 130 can use the display unit (ie, OLED light source) of the OLED display screen 120 located in the fingerprint detection area 103 as an excitation light source for optical fingerprint detection. When the finger 140 is pressed on the fingerprint detection area 103, the display screen 120 emits a beam of light 111 to the target finger 140 above the fingerprint detection area 103. The light 111 is reflected on the surface of the finger 140 to form reflected light or passes through the finger 140. Scattered internally to form scattered light.

It should be understood that, for ease of description, the above-mentioned reflected light and scattered light are collectively referred to as reflected light. Since the ridge and valley of the fingerprint have different light reflection capabilities, the reflected light 151 from the fingerprint ridge 141 and the generated 152 from the fingerprint ridge 142 have different light intensities, and the reflected light passes through the optical component 132. Then, it is received by the sensor array 134 in the optical fingerprint device 130 and converted into a corresponding electrical signal, that is, a fingerprint detection signal; based on the fingerprint detection signal, fingerprint image data can be obtained, and fingerprint matching verification can be further performed, so that The electronic device 10 implements an optical fingerprint recognition function.

With the advent of the era of full-screen mobile phones, the application of under-screen fingerprints has become more and more widespread, among which optical under-screen fingerprints are the most popular. Based on a large amount of engineering technology research and development, the performance of the current optical fingerprint solution applied to the OLED screen still has a certain performance gap with the traditional capacitive optical fingerprint, so it is very urgent to further improve the performance of the optical fingerprint under the screen.

The OLED screen is self-luminous, the screen thickness is thin, and the overall screen structure is made of light-transmitting materials. The above three characteristics determine that it can be used with under-screen optical fingerprints. However, due to the presence of the device structure in the OLED screen, part of the circuit of the device is made of opaque materials, which causes most of the light to be blocked when the light passes through the OLED screen, and the signal that actually reaches the optical chip collection area under the screen through the OLED screen Very weak.

Currently, there are two main solutions for the under-screen optical fingerprint chip in mass production in the industry. One is to use the principle of through-hole small hole imaging, which can guide the light signal reflected by the finger to the sensor chip under the display screen for fingerprint recognition. In theory, the smaller the aperture of the small hole, the higher the resolution. However, in actual industrial manufacturing, the size of the small hole cannot be further reduced, which limits the improvement of its resolution. At the same time, because the small hole only allows the light signal in the vertical direction to enter, the imaging signal is limited, and it is unable to provide enough light signal to the collection area of the sensor chip. Another method uses an optical lens for imaging. This method is similar to the principle of camera imaging, using a spherical or aspheric lens to condense light to improve the imaging resolution. In addition, because the lens has the function of concentrating light, compared to the small hole imaging method, the lens imaging can guide more light signals to the sensor chip.

At present, the under-screen optical fingerprint technology generally uses the light of the screen as the light source, illuminates the fingerprint that touches the screen through the light path, and then the light with the fingerprint signal enters the optical sensor to obtain the fingerprint image.

For fingerprint identification devices based on optical lenses, the most common method is to fix the fingerprint identification device on the screen in the form of frame stickers, so as to realize the bonding between the fingerprint identification device and the screen. In the following, the fingerprint identification method under the screen is taken as an example to describe the connection method of the fingerprint identification device and the display screen.

As shown in FIG. 3, the fingerprint identification device can be arranged under the display screen 400, and the fingerprint identification device includes a circuit board 200, a sensor chip 300, an optical path layer 301 and a microlens array 302. The microlens array 302 is arranged above the optical path layer 301, and is used to converge the optical signal returned by the finger above the display screen onto the optical path layer. The optical path layer 301 is disposed above the sensor chip 300 and below the microlens array 302, and the optical path layer 301 is used to guide optical signals to the sensor chip 300. The sensor chip 300 is arranged on the circuit board 200. Specifically, the sensor chip 300 may be electrically connected to the circuit board 200 by wire bonding or through silicon vias. The sensor chip 300 can be used to generate fingerprint information of a finger according to the optical signal passing through the optical path layer for fingerprint identification.

The circuit board 200 can fix the fingerprint identification device on the display screen 400 through frame glue 201. Frame sticker can be understood as only a circle of frame sticker 201 is arranged around the circuit board, no glue is arranged in the middle area of the circuit board, and the fingerprint identification device is pasted on the display screen through the surrounding frame sticker 201.

Referring to the structure of FIG. 3, it can be seen that the middle area of the fingerprint identification device is exposed in the air. According to the principle of thermal expansion and contraction, when the fingerprint identification device is heated, the fingerprint identification device will warp. In order to prevent the surface of the microlens array 302 from being squeezed onto the display screen 400 due to warping, which affects the fingerprint detection performance and the experience of the screen, it is necessary to reserve a certain amount between the upper surface of the microlens array 302 and the lower surface of the display screen 400. The air gap 303 to compensate for the upward protrusion of the fingerprint identification device.

For the above reasons, the thickness of the air gap layer 303 has a minimum value, which is greater than the change in the thickness of the fingerprint identification device. Generally, the thickness of the air gap layer is 50-100 μm.

However, with the development of technology, users have higher and higher requirements for the thickness of electronic devices. The thickness of fingerprint identification devices also affects the thickness of electronic devices to a certain extent. Therefore, it is urgent to reduce the thickness of fingerprint identification devices. Problems to be solved.

In the structure shown in FIG. 3, the thickness of the fingerprint identification device is limited by the connection method of frame stickers and cannot be further reduced. However, driven by user needs, the embodiment of the present application provides another fingerprint identification device that can Further reduce the thickness of the fingerprint identification device.

As shown in FIG. 4, the fingerprint identification device is suitable for electronic equipment with a display screen 400, and the fingerprint identification device can be arranged under the display screen 400 to form an under-screen fingerprint identification device. The fingerprint identification device may include a microlens array and a sensor chip, the surface of the microlens array is covered with an optical glue layer, the optical glue layer is used to bond the microlens array and the display screen, the sensor chip is used to receive The optical signal returned by the finger and condensed by the microlens array, and the fingerprint image of the finger is generated according to the optical signal.

The solution of the embodiment of this application is not to stick the fingerprint identification device on the display screen by frame sticking, but to set an optical glue layer on the surface of the micro lens array, and directly stick the micro lens on the display screen through the optical glue layer. The surface of the microlens array is not exposed in the air, but is fixed on the display screen by the optical adhesive layer. Even when the fingerprint identification device is heated, the upper surface of the microlens array is fixed by the optical adhesive layer. The thermal expansion and contraction of the microlens array are not particularly obvious.

Based on the foregoing principle, the embodiment of the present application can achieve the purpose of reducing the thickness of the fingerprint identification device by reducing the thickness of the optical adhesive layer. The smaller the thickness of the optical adhesive layer, the smaller the thickness of the fingerprint identification device. Therefore, in the embodiments of the present application, as long as the thickness of the optical adhesive layer can stick the microlens array and the display screen firmly, usually, the optical adhesive layer The thickness can be set at about 20 μm, which is smaller than the thickness of the air layer 303 shown in FIG. 3.

Generally, there is a correspondence between the microlens array and other optical elements (such as light-passing holes) in the fingerprint identification device. If the microlens array is warped, it will cause the microlens array and other optical elements to shift. As a result, the light signal received by the sensor chip becomes weak, which affects the fingerprint detection performance. The solution of connecting the microlens array and the display screen through the optical glue layer can reduce the warpage of the microlens array, thereby helping to improve the fingerprint detection performance.

The optical adhesive layer in the embodiments of the present application may have a certain fluidity. The arrangement of the optical adhesive layer can make there is no air gap between the microlens array and the display screen, that is, the optical adhesive layer can fill up two adjacent ones. The gap between the microlenses is used to fill the uneven surface of the microlenses. In this way, the optical refractive index at different positions between the upper surface of the microlens array and the display screen can be kept uniform, which can simplify the design of the optical elements under the microlens array, and make the microlens array match other optical elements. It becomes easy.

Optionally, the optical adhesive layer is a low refractive index optical adhesive layer, and its refractive index is, for example, less than 1.4.

The traditional more mature technology adopts the frame attachment method shown in FIG. 3. The optical path design of each optical element in the fingerprint identification device is designed according to the refractive index of the air layer 303, and the refractive index of air is usually 1. Therefore, the closer the refractive index of the optical adhesive layer is to the refractive index of air, the more difficult it is to match each optical element in the fingerprint identification device with the optical adhesive layer, and the simpler the design of the optical fingerprint identification device will be.

As a preferred implementation manner, the refractive index of the optical adhesive layer may be 1.1, or may be 1.2.

If there is an optical adhesive layer, it has certain fluidity, can fill the surface of the microlens array, and has sufficient bonding strength, can bond the microlens array and the display screen firmly, and has low refraction Rate, the use of the optical adhesive layer is a preferred way to achieve.

If such an optical adhesive layer is technically difficult to realize, the embodiments of the present application may also use two optical adhesive layers to achieve the above-mentioned purpose. As shown in FIG. 5, the optical adhesive layer may include a first optical adhesive layer 305 and a second optical adhesive layer 306. The first optical glue layer 305 covers the surface of the micro lens array 302, and the second optical glue layer 306 is disposed above the first optical glue layer 305 and is used to bond the micro lens array 302 and the display screen 400. The first optical glue layer The refractive index of the layer 305 may be smaller than the refractive index of the microlens.

The first optical adhesive layer 305 is an optical adhesive layer with a low refractive index, that is, the refractive index of the first optical adhesive layer 305 is less than a preset threshold, for example, less than 1.4.

The first optical glue layer 305 has certain fluidity and can fill the surface of the microlens array 302, so that there is no air gap between the microlens array 302 and the display screen 400. In addition, the surface of the first optical adhesive layer 305 that is in contact with the second optical adhesive layer 306, that is, the upper surface of the first optical adhesive layer 305 is flat, so that the second optical adhesive layer 306 can adhere the microlens array 302 to the display screen 400 To be more reliable.

In the embodiment of the present application, the refractive index of the first optical adhesive layer 305 is lower than the refractive index of the second optical adhesive layer 306, and the low refractive index of the first optical adhesive layer can simplify the design of each optical element in the optical fingerprint identification device.

The refractive index of the first optical adhesive layer 305 may be less than 1.4. As a preferred implementation, the refractive index of the first optical adhesive layer 305 may be 1.1 or 1.2, which is not specifically limited in the embodiment of the present application. Of course, the first The refractive index of the optical adhesive layer 305 may also be 1.3.

The thickness 305 of the first optical glue layer may be greater than the thickness of the microlens array 302, so that the first optical glue layer 305 can completely cover the microlens array 302, that is, the first optical glue layer 305 can cover the highest point of the microlens array 302 , So that the surface of the microlens array after covering the glue layer is flat. As shown in FIG. 6, the thickness of the micro lens array is d2, and the thickness of the first optical adhesive layer is d1, where d1>d2.

Generally, the thickness of the first optical adhesive layer 305 is only 1 to 2 μm larger than the thickness of the micro lens array 302, that is, d1-d2=1 to 2 μm. This not only ensures that the surface of the microlens array is flat, but also does not greatly affect the thickness of the fingerprint identification device.

The second optical adhesive layer 306 has a certain bonding strength, which can stick two optical elements with flat surfaces firmly. The second optical adhesive layer may be, for example, an optical clear adhesive (OCA).

The embodiment of the present application does not specifically limit the thickness of the second optical adhesive layer, and can be selected according to requirements, as long as the bonding strength between the microlens array and the display screen can be ensured. The thickness d3 of the second optical adhesive layer may be greater than 10 μm, for example.

The embodiments of the present application do not specifically limit the composition of the first optical adhesive layer. For example, the first optical adhesive layer may be a resin-based optical adhesive layer, and the resin may be, for example, an epoxy resin or a phenolic resin.

In the embodiment of the present application, the first optical adhesive layer and the second optical adhesive layer need to have a certain light transmittance so as to be able to transmit the light signal reflected by the finger above the display screen to the sensor chip 300.

If the fingerprint identification device uses a self-luminous display screen as a light source, the first optical adhesive layer and the second optical adhesive layer need to have a certain light transmittance to visible light. If the fingerprint identification device uses an external light source (such as infrared light) as the light source, the first optical adhesive layer and the second optical adhesive layer need to have a certain light transmittance to infrared light.

Taking visible light as an example, the transmittance of the first optical adhesive layer 305 to visible light is greater than 80%, and/or the transmittance of the second optical adhesive layer 306 to optical signals in the visible light band is greater than 90%.

In the embodiment of the present application, the coverage area of the optical adhesive layer 304 shown in FIG. 4 or the first optical adhesive layer 305 shown in FIG. 5 is larger than the area of the microlens array 302, so as to ensure that the microlenses are completely covered.

As a preferred implementation manner, the coverage area of the optical adhesive layer 304 shown in FIG. 4 or the first optical adhesive layer 305 shown in FIG. 5 may be equal to the area of the sensor chip, for example, the side surface of the sensor chip of the optical adhesive layer is kept flush . In this way, the appearance is more beautiful, and the coverage area of the optical adhesive layer can be increased, so that the micro lens array and the display screen can be bonded more firmly.

The embodiment of the present application does not specifically limit the connection manner between the sensor chip 300 and the circuit board 200, and the connection may be made by wire bonding or through silicon via.

Figure 7 shows a schematic structural diagram of a wire bonding connection. This method can also be called a wire bond (WB) connection method. In the structure shown in FIG. 7, the circuit board 200 may be a substrate or a flexible printed circuit (FPC) material, and its thickness may range from 50 to 300 μm. There is a metal pad 202 on the circuit board 200, and a metal pad 308 on the side of the sensor chip 300. The metal pad 202 and the metal pad 308 are connected by a wire bond 302, and can be connected by The glue 307 protects the gold wire, thereby realizing the electrical connection between the sensor chip 300 and the circuit board 200.

FIG. 8 shows a schematic structural diagram of a connection method using through silicon vias. The circuit board 200 may be a substrate or FPC material, and its thickness may range from 50 to 300 μm. There are metal pads 203 on the circuit board 200, a through hole 310 is formed in the sensor chip 300, and a metal pad 309 is formed on its side. The metal pad 203 and the metal pad 309 are connected through the through hole 310 to realize the sensor chip 300 Electrical connection with the circuit board 200.

The circuit board in the embodiment of the present application may also be referred to as a carrier board.

The sensor chip can be a silicon chip chip, which can be ground and thinned to a specific thickness as required.

Optionally, the fingerprint identification device in the embodiment of the present application may further include an optical path layer 301 disposed under the microlens array 302 for guiding the optical signals passing through the microlens array 302 to the sensor chip 300.

As an example, as shown in FIG. 9, the optical path layer may include a light blocking layer 312, on which a small hole array 313 is provided, and the small hole array 313 is used to guide the optical signal passing through the microlens array 302 To the sensor chip 300.

The sensor chip in the embodiment of the present application may include a fingerprint sensor, the fingerprint sensor may include a plurality of sensing arrays, the plurality of sensing arrays may include a plurality of pixel units 314, and the light blocking layer 312 may be formed above the sensing array. The light blocking layer 312 may be provided with a plurality of light-passing holes 313, the microlens array 302 may be disposed above the light blocking layer 312, and the microlens array 302 may include a plurality of microlenses.

The microlens array 302 can be used to converge the light signals returned from the finger to the light-passing holes 313 on the light-blocking layer 312, and then the light-passing holes 313 can guide the light signals to the fingerprints under the light-blocking layer 312 For the sensor, the light signal passing through the light-passing hole 313 can be received by the pixel unit 314 under the light blocking layer 312, and the pixel unit 314 can perform fingerprint recognition according to the received light signal.

In the embodiment of the present application, each microlens in the microlens array 302 may include a corresponding aperture and pixel unit, and the center of each microlens and the center of the corresponding aperture and the center of the pixel unit It can be located on a straight line, which can ensure that the light signal focused by the microlens can be received by the pixel unit. Optionally, the straight line may be perpendicular to the plane where the sensor chip 200 is located, and the angle between the line and the plane where the sensor chip 200 is located is less than 90 degrees. It is not difficult to understand that when the angle between the straight line and the plane where the sensor chip 200 is located is less than 90 degrees, the center of each microlens, its corresponding light-passing hole, and the pixel unit are in the horizontal direction. A certain separation distance, the separation distance depends on the actual situation, as long as it can ensure that the light signal after being focused by the microlens can be received by its corresponding pixel unit.

The solution of the transparent optical adhesive layer of the embodiment of the present application for bonding the microlens array to the display screen can reduce the warpage of the microlens, thereby improving the gap between the microlens and its corresponding transparent aperture and pixel unit. Dislocation phenomenon. In the case of serious misalignment between the microlens and its corresponding light hole and pixel unit, the light signal received by the pixel unit will be greatly reduced, which will affect the fingerprint recognition performance. The solution provided by the embodiment of this application can improve The phenomenon.

The embodiment of the application does not specifically limit the number of light-blocking layers. The fingerprint identification device may include one light-blocking layer or multiple light-blocking layers, and the multiple light-blocking layers can be arranged in a stacked manner.

Optionally, the optical path layer in the embodiment of the present application may further include a filter layer 311, which can be used to filter out optical signals in a specific wavelength band. For example, the filter layer 311 can be used to filter out non-fingerprint detection wavelength bands. Light signal. The optical signal of the fingerprint detection band can be understood as the optical signal reflected by the finger received by the fingerprint sensor.

If the fingerprint detection uses the light emitted by the self-luminous screen as the light source, the filter layer 311 can be used to filter out infrared and/or red light waveband light signals.

The filter layer 311 can be arranged on any surface in the fingerprint identification device. For example, the filter layer 311 may be provided on the upper surface of the sensor chip 200 to prevent light signals in the non-fingerprint detection waveband from entering the sensor chip, which affects the fingerprint detection performance.

Of course, the filter layer 311 can also be provided on other surfaces. For example, the filter layer 311 can be provided on the upper surface or the lower surface of the light blocking layer. For example, the filter layer 311 can be provided on the microlens array 302. surface.

The microlens array 302 in the embodiment of the present application can be used to guide vertical light or oblique light, which is not specifically limited in the embodiment of the present application.

The microlens in the embodiment of the present application may be a circular lens, or the microlens may be a polygonal lens, such as a square lens or a hexagonal lens.

Optionally, the optical path layer in the embodiment of the present application may further include other structures, for example, may include a collimating hole array.

The bonding of the microlens array and the display screen described in the embodiments of the present application may refer to the bonding of the entire fingerprint identification device and the screen.

FIG. 10 is a schematic block diagram of an electronic device according to an embodiment of the present application. The electronic device 1000 includes a display screen 1010 and a fingerprint identification device 1020. The fingerprint identification device 1020 can be arranged below the display screen 1010 to perform fingerprint identification on the fingers above the display screen 1010.

The display screen 1010 may be any display screen described above, and the display screen 1010 may be, for example, a self-luminous display screen, such as an OLED screen.

The fingerprint identification device 1020 may be any of the fingerprint identification devices described above. To simplify the description, the details will not be repeated here.

It should be noted that the sensor chip in the embodiment of the present application may also be referred to as a fingerprint sensor.

It should be noted that the terms used in the embodiments of the present application and the appended claims are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application.

For example, the singular forms of "a", "said", "above" and "the" used in the embodiments of this application and the appended claims are also intended to include plural forms, unless the context clearly indicates other forms. meaning.

Those skilled in the art may be aware that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software depends on the specific application and design constraint conditions of the technical solution. Professionals and technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered as going beyond the scope of the embodiments of the present application.

If implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the embodiments of the present application are essentially or the part that contributes to the prior art or the part of the technical solutions can be embodied in the form of a software product, and the computer software product is stored in a storage medium , Including several instructions to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the method described in the embodiments of this application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory, random access memory, magnetic disk or optical disk and other media that can store program codes.

Those skilled in the art can clearly understand that, for the convenience and conciseness of the description, the specific working process of the equipment, device and unit described above can refer to the corresponding process in the foregoing method embodiment, which is not repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed electronic equipment, apparatus, and method may be implemented in other ways.

For example, the division of units or modules or components in the device embodiments described above is only a logical function division, and there may be other divisions in actual implementation. For example, multiple units or modules or components can be combined or integrated. To another system, or some units or modules or components can be ignored or not executed.

For another example, the aforementioned units/modules/components described as separate/display components may or may not be physically separated, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units/modules/components may be selected according to actual needs to achieve the objectives of the embodiments of the present application.

Finally, it should be noted that the mutual coupling or direct coupling or communication connection shown or discussed above may be indirect coupling or communication connection through some interfaces, devices or units, and may be in electrical, mechanical or other forms. .

The above content is only the specific implementation manners of the embodiments of the present application, but the protection scope of the embodiments of the present application is not limited thereto. Any person skilled in the art can easily think of within the technical scope disclosed in the embodiments of the present application. The change or replacement shall be covered within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of the present application should be subject to the protection scope of the claims.

Claims

A fingerprint identification device, suitable for electronic equipment with a display screen, characterized in that the fingerprint identification device is configured to be arranged below the display screen, and the fingerprint identification device includes:

A microlens array, the surface of the microlens array is covered with an optical glue layer, and the optical glue layer is used to bond the microlens array and the display screen;

The sensor chip is used for receiving the light signal returned by the finger above the display screen and condensed by the microlens array, and generating a fingerprint image of the finger according to the light signal.
The fingerprint identification device according to claim 1, wherein the optical glue layer is arranged such that there is no air gap between the microlens array and the display screen.
The fingerprint identification device according to claim 1 or 2, wherein the optical adhesive layer comprises a first optical adhesive layer and a second optical adhesive layer, and the first optical adhesive layer covers the microlens array On the surface, the second optical adhesive layer is arranged above the first optical adhesive layer and is used to bond the microlens array and the display screen, and the refractive index of the first optical adhesive layer is smaller than that of the micro The refractive index of the microlenses in the lens array.
The fingerprint identification device according to claim 3, wherein the surface of the first optical adhesive layer that is in contact with the second optical adhesive layer is flat.
The fingerprint identification device according to claim 3 or 4, wherein the refractive index of the first optical adhesive layer is lower than the refractive index of the second optical adhesive layer.
The fingerprint identification device according to any one of claims 3-5, wherein the refractive index of the first optical adhesive layer is less than 1.4.
The fingerprint identification device according to any one of claims 3-6, wherein the refractive index of the first optical adhesive layer is 1.1 or 1.2.
7. The fingerprint identification device according to any one of claims 3-7, wherein the thickness of the first optical glue layer is greater than the thickness of the microlens array.
8. The fingerprint identification device according to any one of claims 3-8, wherein the thickness of the first optical glue layer is 1 to 2 μm larger than the thickness of the microlens array.
The fingerprint identification device according to any one of claims 3-9, wherein the thickness of the first optical adhesive layer is 5-10 μm.
The fingerprint identification device according to any one of claims 3-10, wherein the transmittance of the first optical adhesive layer to light signals in the visible light band is greater than 80%, and/or, the second The transmittance of the optical adhesive layer to light signals in the visible light band is greater than 90%.
The fingerprint identification device according to any one of claims 3-11, wherein the thickness of the second optical adhesive layer is greater than 10 μm.
The fingerprint identification device according to any one of claims 3-12, wherein the second optical adhesive layer is an optically transparent adhesive layer OCA.
The fingerprint identification device according to any one of claims 1-13, wherein the coverage area of the optical glue layer is larger than the area of the microlens array.
14. The fingerprint identification device according to any one of claims 1-14, wherein the coverage area of the optical adhesive layer is equal to the area of the sensor chip.
The fingerprint identification device according to claim 15, wherein the optical adhesive layer is flush with the side surface of the sensor chip up and down.
The fingerprint identification device according to any one of claims 1-16, wherein the fingerprint identification device further comprises a circuit board, and the sensor chip is electrically connected to the Circuit board.
The fingerprint identification device according to any one of claims 1-17, wherein the fingerprint identification device comprises an optical path layer, and the optical path layer is arranged below the microlens array and configured to pass through the The optical signal of the microlens array is guided to the sensor chip.
The fingerprint identification device according to claim 18, wherein the light path layer comprises a light blocking layer, the light blocking layer is provided with a small hole array, and the small hole array is used to pass the light passing through the micro lens array. The signal is directed to the sensor chip.
The fingerprint identification device according to claim 18 or 19, wherein the optical path layer comprises a filter layer, and the filter layer is used to filter out optical signals of a specific wavelength band.
22. The fingerprint identification device according to claim 20, wherein the filter layer is used to filter out infrared and/or red light waveband optical signals.
The fingerprint identification device according to claim 20 or 21, wherein the filter layer is plated on the upper surface of the sensor chip.
An electronic device, characterized in that it comprises:

Display screen

And the fingerprint identification device according to any one of claims 1-22, the fingerprint identification device is arranged below the display screen.