TW202210913A - Fingerprint identification assembly and display device - Google Patents

Abstract

A fingerprint identification assembly used for fingerprint identification under a screen includes an optical sensor assembly, at least two light-emitting elements, at least two first polarizers, a second polarizer, and at least two polarization rotators. Each light-emitting element is arranged nearby the optical sensor assembly. The optical sensor assembly is used to collect the light emitted by the light-emitting elements and reflected by a finger, to form a fingerprint image. A light emitting surface side of each light emitting element is provided with one of the first polarizers. The second polarizer faces the optical sensor assembly and is located on the side from where the optical sensor assembly obtains fingerprint light signals, and the axis of the first polarizer and the axis of the second polarizer are perpendicular to each other. Each polarization rotator faces one of one of the first polarizers and is located on the side of the first polarizer away from the light-emitting element. Each polarization rotator is used to rotate the polarized light generated by the first polarizer to change the polarization state of the polarized light. The disclosure also provides a display device using the fingerprint identification assembly.

Description

Fingerprint recognition module and display device

The invention relates to a fingerprint identification module and a display device.

The glass on the screen of the display device has no holes and the fingerprint recognition function (ie, full-screen fingerprint recognition) is favored by users. Full-screen fingerprint recognition is currently dominated by optical and ultrasonic fingerprints. Ultrasonic fingerprint recognition is expensive and is easily limited by the thickness of penetration and the applicable screen. Optical identification is relatively low cost, and the penetration thickness and applicable screen restrictions are small.

In the fingerprint recognition module under the display screen, when the display screen uses the auxiliary light source as the auxiliary light source for optical fingerprint detection to generate a fingerprint image, the auxiliary light source of the fingerprint recognition module and the optical sensing module for collecting the fingerprint image are located on the display screen. below the screen. Structural parts (such as reflective sheets) in the display screen will reflect a part of the light emitted by the auxiliary light source, and make it enter the optical sensing module, becoming stray light in the process of collecting fingerprint optical signals, and stray light can easily lead to optical transmission. The imaging quality of the sensor module is disturbed, which affects the correctness of fingerprint recognition.

One aspect of the present invention provides a fingerprint identification module for fingerprint identification under the screen, which includes: Optical sensor module; at least two light-emitting elements, each light-emitting element is disposed on the periphery of the optical sensing module, the optical sensing module is used to collect the light emitted by the light-emitting element and reflected by the finger to form a fingerprint image; One side of the light-emitting surface of each light-emitting element is provided with a first polarizer; The second polarizer is opposite to the optical sensing module and is located on the side where the optical sensing module obtains the fingerprint light signal, and the polarization axis of the first polarizer is the same as the polarization axis of the second polarizer. The axes are perpendicular to each other; and, A polarization rotator is arranged opposite each first polarizer, and each polarization rotator is located on the side of the first polarizer away from the light-emitting element, and is used to rotate the polarized light generated by the first polarizer to change the The polarization state of the polarized light.

display screen; a cover plate, covering the display screen to protect the display screen; a backlight module, located on the side of the display screen away from the cover plate; and, The fingerprint identification module is located on the side of the backlight module away from the display screen and is used for fingerprint identification under the display screen.

Compared with the prior art, the fingerprint identification module utilizes the first polarizer, the second polarizer and the polarization rotator to suppress the stray light of the non-fingerprint signal from entering the optical sensing module, effectively. Therefore, the clarity of the fingerprint image generated by the optical sensing module is improved.

The drawings illustrate embodiments of the present invention, which may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Example 1

Referring to FIG. 1 , a display device 100 provided by Embodiment 1 of the present invention includes a display screen 20 and a fingerprint identification module 10 located under the display screen 20 . When a finger presses the display device 100 , the fingerprint identification module Group 10 is used for fingerprint image collection and fingerprint recognition under the screen.

In this embodiment, the display screen 20 is a liquid crystal display screen, which may include a color filter substrate, a thin film transistor (TFT) array substrate disposed opposite to the color filter substrate, and a substrate located on the color filter substrate. The liquid crystal layer between the filter substrate and the TFT array substrate, the display screen 20 further includes an upper polarizer located on the side of the color filter substrate away from the liquid crystal layer, and an upper polarizer located on the side of the color filter substrate away from the liquid crystal layer and an upper polarizer located on the TFT array substrate away from the liquid crystal layer Lower polarizer on one side.

As shown in FIG. 1 , the fingerprint identification module 10 includes an optical sensor module 101 , at least two light-emitting elements 102 , a first polarizer 103 , a second polarizer 104 and a polarization rotator 105 . The at least two light-emitting elements 102 are arranged around the optical sensing module 101 , and the light-emitting surface of each light-emitting element 102 faces the display screen 20 , that is, faces the optical sensing module 101 to obtain the fingerprint light signal. direction. One side of the light-emitting surface of each light-emitting element 102 is provided with a first polarizer 103 , and the first polarizer 103 polarizes the light emitted by the light-emitting element 102 . The second polarizer 104 faces the optical sensor module 101 and is located on the side where the optical sensor module 101 obtains the fingerprint light signal, that is, the second polarizer 104 is located on the optical sensor module 101 . The module 101 is close to one side of the display screen 20 ; the polarization axis of the first polarizer 103 and the polarization axis of the second polarizer 104 are perpendicular to each other. A polarization rotator 105 is disposed opposite to each first polarizer 103, and each polarization rotator 105 is located on the side of the first polarizer 103 away from the light-emitting element 102, and is used for rotating the polarization rotator. The polarized light generated by the pair of first polarizers 103 changes the polarization state of the polarized light. Each polarization rotator 105 is located on the optical path of the polarized light generated by the first polarizer 103 facing it.

In this embodiment, the light-emitting element 102 is used as an auxiliary light source for fingerprint detection, and the optical sensing module 101 is used to collect the light emitted by the light-emitting element 102 and reflected by the finger to form a fingerprint image.

In this embodiment, each of the light-emitting elements 102 is parallel to the first polarizer 103 located on one side of the light-emitting surface thereof; each polarization rotator 105 is parallel to the first polarizer 103 facing it.

In this embodiment, the polarization rotator 105 is located between the display screen 20 and the first polarizer 103 , and the second polarizer 104 is located between the optical sensing module 101 and the display screen between 20. Each polarization rotator 105 and its opposite first polarizer 103 are spaced apart. The size of the space is not limited, as long as it is ensured that the first polarizer 103 can generate polarized light through the polarization rotator. 105 is enough. In other embodiments, each of the polarization rotators 105 and the first polarizer 103 facing each other can also be arranged without intervals, which is designed according to the actual situation.

Referring to FIG. 2 , the display device 100 further includes a backlight module 30 to provide the display screen 20 with a light source required for image display. The backlight module 30 is located between the display screen 20 and the fingerprint identification module 10 . The backlight module 30 includes a reflective sheet 301 located on the side of the display screen 20 close to the fingerprint recognition module 10, a light guide plate 303 located between the reflective sheet 301 and the display screen 20, and a light guide plate 303 located on the side of the display screen 20. The reflective sheet 301 and the backlight source 302 on one side of the display screen 20 . The reflection sheet 301 reflects the light emitted by the backlight source 302, and the light guide plate 303 guides the light emitted by the backlight source 302, so that the reflection sheet 301 and the light guide plate 303 are beneficial to make the backlight source become The surface light source of the display screen 20 . In this embodiment, each polarization rotator 105 is located on the side of the reflection sheet 301 away from the display screen 20 .

In one embodiment, each polarization rotator 105 may be attached to a side of the reflective sheet 301 away from the display screen 20 .

In the conventional fingerprint recognition module, when the light emitted by each light-emitting element enters the reflective sheet, the light emitted by the light-emitting element will be reflected by the reflective sheet to enter the optical sensing module and become the optical sensing module The stray light when collecting the fingerprint light signal causes the fingerprint image to be blurred. However, in this embodiment, the light emitted by each light-emitting element 102 passes through a first polarizer 103 to become polarized light A of a specific polarization state, when part of the polarized light A of the specific polarization state is reflected by the reflecting plate 301 When reaching the second polarizer 104, since the polarization axis of the second polarizer 104 and the polarization axis of the first polarizer 103 are perpendicular to each other, the polarized light A of this part of the specific polarization state cannot pass through the second polarizer 104. The two polarizers 104 enter the optical sensing module 101 . Therefore, the combined use of the second polarizer 104 and the first polarizer 103 can effectively avoid the blurring of the fingerprint image caused by the aforementioned stray light entering the optical sensing module 101 .

In this embodiment, the light-emitting surface of each light-emitting element 102 is covered by one of the first polarizers 103 , and the side of the optical sensing module 101 that obtains the fingerprint light signal is covered by the second polarizer. Therefore, each first polarizer 103 can make the light emitted by each light-emitting element 102 into polarized light as much as possible, and make the light reflected by the fingerprint of the finger first enter the second polarizer 104 and then enter the optical sensor. Module 101. In this way, the aforementioned stray light can be prevented to the greatest extent from entering the optical sensing module 101, thereby causing blurring of the fingerprint image.

While preventing the stray light from entering the optical sensing module 101 , in order to ensure that the polarized light A transmitted to the finger through the display screen 20 and reflected by the finger can pass through the second polarizer 104 Enter the optical sensor module 101 . Further, in this embodiment, the polarization rotator 105 is disposed on one side of the light-emitting surface of each light-emitting element 102 and at a position facing each of the first polarizers 103 . Because the polarization rotator 105 rotates the polarized light A generated by the first polarizer 103 and changes the polarization state of the polarized light A, the polarized light A transmitted to the finger and reflected by the finger can be transmitted through the The second polarizer 104 enters the optical sensing module 101 .

In this embodiment, the backlight module 30 further includes a diffusion sheet and a brightness enhancement sheet (not shown in the figure) that are stacked between the reflection sheet 301 and the display screen 20 .

In this embodiment, each light emitting element is a light emitting diode (LED). The distance, inclination angle and arrangement between each light-emitting element 102 and the optical sensing module 101 are not specifically limited. The arrangement of each light-emitting element 102 around the optical sensing module 101 may be in a grid-like, concentric manner Any shape such as round, diagonal, etc. FIG. 3 illustrates a situation in which four light-emitting elements form a rectangular grid and concentric circles around the optical sensing module 101 .

In this embodiment, each light-emitting element 102 emits visible light or invisible light. The first polarizer 103 , the second polarizer 104 and the polarization rotator 105 are selected according to the wavelength range of the light emitted by each light-emitting element 102 . Specifically, when each light-emitting element 102 emits visible light, the first polarizer 103 and the second polarizer 104 are visible light polarizers, and the polarization rotator 105 is used to rotate the first polarizer 103 Generated polarized light within the wavelength range of visible light and change the polarization state of the polarized light; at this time, the polarization rotator 105 is made of birefringent plastic, glass or other light-transmitting material. When each light-emitting element 102 emits invisible light, the first polarizer 103 and the second polarizer 104 are invisible light polarizers, and the polarization rotator 105 is used to rotate the first polarizer 103 to generate The polarization rotator 105 is made of semiconductor material at this time.

In one embodiment, the polarization rotator 105 may be a half-wave plate. The first polarizer 103 and the second polarizer 104 may be wire grid polarizers, and the interval between the tooth-like structures in the grid of the wire grid polarizer is 50 nm to 250 nm, and the The duty cycle of the tooth structure in the grid is in the range of 0.2 to 0.6. As shown in FIG. 2 , the optical sensor module 101 further includes a lens barrel 1011 , a lens 1012 located in the lens barrel 1011 , and a sensing chip 1013 located on the side of the lens barrel 1011 away from the second polarizer 104 . The second polarizer 104 is located on the side of the lens barrel 1011 away from the sensing wafer 1013 and faces the lens 1012 . The lens barrel 1011 is used for fixing the lens 1012 , the lens 1012 is used for collecting fingerprint light signals, and the sensor chip 1013 is used for imaging according to the fingerprint light signals collected by the lens 1012 .

In one embodiment, the second polarizer 104 is located on the lens barrel 1011, and the second polarizer 104 covers the lens barrel 1011, so that the light entering the optical sensing module 101 first passes through the lens barrel 1011. The second polarizer is beneficial to prevent the aforementioned stray light.

In this embodiment, the lens 1012 includes at least one lens (not shown). The sensor wafer 1013 can be, but is not limited to, an optical fingerprint sensor. The sensing wafer 1013 can be a sensing array (not shown) including a plurality of optical sensing units. In this case, the lens 1012 has a microlens array formed by a plurality of microlenses, and the microlens array is located on the sensing wafer. 1013 above the sensing array, and each microlens may correspond to one of the sensing units of the sensing array.

As shown in FIG. 2 , the display device 100 further includes a cover plate 50 , the cover plate 50 is located on the side of the display screen 20 away from the backlight module 30 , and the cover plate 50 covers the display screen 20 to protect the display screen 20 .

In this embodiment, the cover plate 50 may be a transparent cover plate, such as a glass cover plate or a sapphire cover plate. Pressing the display device 300 by a human finger may actually refer to pressing the cover plate 50 by a finger.

In this embodiment, the display device 100 further includes a circuit board located on the side of the optical sensing module 101 away from the second polarizer 104 . The optical sensing module 101 can be soldered to the circuit board by soldering pads, and realize electrical interconnection and signal transmission with other elements of the display device 300 through the circuit board. The circuit board may be a flexible printed circuit (FPC).

Embodiment 2

Referring to FIG. 4 , the display device 200 provided by the second embodiment of the present invention includes the above-mentioned display screen 20 , the backlight module 30 , and a fingerprint recognition module 40 located under the display screen 20 . When a finger presses the display device 200 , the fingerprint identification module 40 is used for fingerprint image collection and fingerprint identification under the screen. The fingerprint recognition module 40 also includes the optical sensor module 101 , at least two light-emitting elements 102 , the first polarizer 103 , the second polarizer 104 and the polarization rotator 105 . The positions and functions of the optical sensing module 101 , each light-emitting element 102 , the first polarizer 103 , the second polarizer 104 and the polarization rotator 105 in the display device 200 are the same as those in the display device 200 . The positions and functions in the display device 200 are the same.

As shown in FIG. 4 , the fingerprint recognition module 40 further includes a polarizer group 106 . The polarizer group 106 is disposed facing the second polarizer 104 and located at the second polarizer 104 away from the optical One side of the sensing module 101 . The polarizing plate group 106 is composed of a third polarizing plate 1061 and a fourth polarizing plate 1062 that are stacked along the direction of the polarizing plate group 106 to the second polarizing plate 104 , and the polarization axis of the third polarizing plate 1061 is It is perpendicular to the polarization axis of the fourth polarizer 1062 . In this embodiment, the upper and lower positions of the third polarizer 1061 and the fourth polarizer 1062 can be changed, and the third polarizer 1061 and the fourth polarizer 1062 can be attached together or arranged at intervals. As long as the polarization axis of the third polarizer 1061 and the polarization axis of the fourth polarizer 1062 are perpendicular to each other, the orthographic projection of the third polarizer 1061 on the fourth polarizer 1062 at least partially covers the fourth polarizer 1062.

In this embodiment, the polarizing plate group 106 and the second polarizing plate 104 are arranged at intervals. The polarizer group 106 is located on the side of the reflection sheet 301 away from the display screen 20 , and the polarizer group 106 can be attached to the reflection sheet 301 . The size of the interval between the polarizer group 106 and the second polarizer 104 is not particularly limited, as long as the light energy from the polarizer group 106 can be transmitted to the second polarizer 104 . In other embodiments, the polarizing plate group 106 and the second polarizing plate 104 may also be arranged without intervals, and are designed according to actual conditions.

In this embodiment, each light-emitting element 102 is a near-infrared light-emitting diode, the first polarizer 103 and the second polarizer 104 are near-infrared light polarizers, and the polarization rotator 105 is made of a semiconductor material. And the third polarizer 1061 and the fourth polarizer 1062 are both visible light polarizers. It can be understood that, at this time, the polarizer group 106 formed by the third polarizer 1061 and the fourth polarizer 1062 can only polarize visible light, but cannot polarize the near-infrared light emitted by each light-emitting element 102 . In other embodiments, each light emitting element 102 emits other wavelength ranges of invisible light.

In this embodiment, the third polarizer 1061 and the fourth polarizer 1062 may be visible light polarizers composed of absorbing polymer materials or visible light polarizers composed of birefringent materials, but not limited thereto.

In the above fingerprint recognition module 10 that does not include the polarizer group 106, when the display screen 20 is on, the light emitted by the backlight source 302 of the display screen 20 will pass through the reflection sheet 301, So that the optical sensor module 101 under the display screen 20 will simultaneously receive the light emitted by the light-emitting element 102 and reflected by the finger and the light emitted by the backlight source 302 of the display screen 20, thereby causing the optical transmission The fingerprint image collected by the sensor module 101 is blurred or even overexposed. Of course, in the fingerprint recognition module 40, the third polarizer 1061 and the fourth polarizer 1062, which polarize visible light and whose polarization axes are perpendicular to each other, can attenuate the light emitted by the backlight source 302 to less than 0.005% , thereby preventing the light emitted by the backlight source 302 of the display screen 20 from entering the optical sensing module 101 .

In this embodiment, when the same polarizer for visible light is used, the near-infrared light emitted by each light-emitting element 102 passes through the visible light polarizer (the first polarizer 103 and the second polarizer 104 ). The transmittance can reach more than 90%. Therefore, under the same illuminance, the difference between the near-infrared light intensity and the visible light intensity received by the optical sensing module 101 is 4 to 5 series (the difference between the near-infrared light intensity and the visible light intensity is 104 to 105), Therefore, the use of the light-emitting element 102 that emits near-infrared light can effectively improve the efficiency of the fingerprint identification module 40 in detecting fingerprint images.

In one embodiment, the third polarizer 1061 and the fourth polarizer 1062 whose polarizing axes are perpendicular to each other are disposed opposite each other and have the same size to ensure the amount of light passing through the third polarizer 1061 The amount of light passing through the fourth polarizer 1062 is the same; the orthographic projection of the polarizer group 106 on the second polarizer 104 completely covers the second polarizer 104 . In this way, the light emitted by the backlight source 302 is made to pass through the polarizing plate group 106 and then enter the optical sensor module 101 as much as possible, thereby further effectively suppressing blurring and excessive fingerprint images caused by the backlight source 302 Exposure issues.

The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. The up, down, left and right directions appearing in the drawings are only for the convenience of understanding. Although the present invention has been described in detail with reference to the preferred embodiments, the Those of ordinary skill should understand that the technical solutions of the present invention may be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

100, 200: Display device 10, 40: Fingerprint recognition module 20: Display 101: Optical sensor module 1011: Lens Barrel 1012: Shots 1013: Wafer Sensing Wafer 102: Light-emitting element 103: The first polarizer 104: Second polarizer 105: Polarization Rotator 106: polarizer group 1061: The third polarizer 1062: Fourth polarizer 30: Backlight module 301: Reflector 302: Backlight 303: light guide plate 50: cover plate

FIG. 1 is a schematic structural diagram of a display device and a fingerprint identification module according to Embodiment 1 of the present invention.

FIG. 2 is a schematic structural diagram of a display device including a backlight module according to Embodiment 1 of the present invention.

FIG. 3 is a one-sided schematic view of the light-emitting element surrounding the optical sensing module.

FIG. 4 is a schematic structural diagram of a display device and a fingerprint identification module according to Embodiment 2 of the present invention.

100: Display device

10: Fingerprint recognition module

20: Display

101: Optical sensor module

102: Light-emitting element

103: The first polarizer

104: Second polarizer

105: Polarization Rotator

Claims (11)

A fingerprint identification module is used for fingerprint identification under the screen, and the improvement is that it includes: an optical sensor module; at least two light-emitting elements, each light-emitting element is disposed on the periphery of the optical sensing module, the optical sensing module is used to collect the light emitted by the light-emitting element and reflected by the finger to form a fingerprint image; One side of the light-emitting surface of each light-emitting element is provided with a first polarizer; A second polarizer, facing the optical sensing module and located on the side where the optical sensing module obtains the fingerprint light signal, the polarization axis of the first polarizer and the polarization axis of the second polarizer perpendicular to each other; and A polarization rotator is arranged facing each first polarizer, and each polarization rotator is located on the side of the first polarizer away from the light-emitting element, and is used to rotate the first polarization that is opposite to the polarization rotator The polarized light produced by the sheet changes the polarization state of the polarized light. The fingerprint identification module according to claim 1, wherein the light-emitting surface of each light-emitting element is covered by one of the first polarizers, and the side where the optical sensing module obtains the fingerprint light signal is covered by the second polarizer. Polarizer overlay. The fingerprint identification module according to claim 1, wherein when each light-emitting element emits visible light, each of the first polarizer and the second polarizer is a visible light polarizer, and the polarization rotator is used to rotate all the The first polarizer generates polarized light in the visible wavelength range to change the polarization state of the polarized light. The fingerprint identification module according to claim 1, wherein when each light-emitting element emits invisible light, each first polarizer and the second polarizer are invisible light polarizers, and the polarization rotator is used for The polarized light in the invisible wavelength range produced by the first polarizer is rotated to change the polarization state of the polarized light. The fingerprint identification module according to claim 4, wherein the fingerprint identification module further comprises a polarizer set facing the second polarizer, and the polarizer group is located at a distance from the second polarizer. one side of the optical sensing module; the polarizer group is composed of two polarizers stacked along the direction of the polarizer group toward the second polarizer, and the polarization axes of the two polarizers are perpendicular to each other . The fingerprint identification module according to claim 5, wherein the light-emitting element is a near-infrared light-emitting diode, the first polarizer and the second polarizer are near-infrared light polarizers, and the Both polarizers of the polarizer group are visible light polarizers. The fingerprint identification module according to claim 5, wherein the two polarizers of the polarizer group are of the same size and are arranged facing each other; the orthographic projection of the polarizer group on the second polarizer completely covers the second polarizer. The fingerprint identification module according to claim 1, wherein the first polarizer and the second polarizer are wire grid polarizers, and the tooth-like structures in the grid of the wire grid polarizer are The interval ranges from 50 nm to 250 nm, and the duty cycle of the tooth-like structures in the grid ranges from 0.2 to 0.6. The fingerprint identification module according to claim 1, wherein the polarization rotator is a half-wave plate. The fingerprint identification module according to claim 1, wherein the optical sensing module further comprises a lens barrel, a lens located in the lens barrel, and a sensing chip located on the side of the lens barrel away from the second polarizer , the second polarizer is located on the side of the lens barrel away from the sensing chip and is facing the lens, the lens is used for condensing fingerprint light signals, and the sensing chip is used for converging according to the lens The fingerprint light signal is imaged. A display device, which is improved by comprising: display screen; a cover plate, covering the display screen to protect the display screen; a backlight module, located on the side of the display screen away from the cover; and The fingerprint identification module according to any one of claims 1 to 10, wherein the fingerprint identification module is located on a side of the backlight module away from the display screen, and is used for fingerprint identification under the display screen.

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