TWI696120B - Light guide element - Google Patents

Abstract

The present invention relates to a light guide element. The light guide element includes a first surface, a plurality of semi-penetration films, and a second surface. The first surface corresponds to an object to be measured. The semi-penetration films are disposed parallel to each other inside the light guide element. The second surface includes a light guide area, and the position of the light guide area corresponds to an optical sensor.

Description

Light guide element

The technology of the present invention relates to the field of fingerprint identification, in particular to a light guide element suitable for an optical fingerprint identification module.

Fingerprint (fingerprint) is the texture of the skin of the fingertips of primates, generally also refers to the marks left by these textures on objects. The fingerprints of all people in ancient and modern China and abroad are unique. The shape of fingerprint patterns is related to human genes, but it is impossible to reconstruct fingerprint patterns by analyzing human genes.

Due to the difference and stability of fingerprints, fingerprints were used for identification as early as ancient China. At that time, people used fingerprints to draw, until the Western modern era. After 1980, the police gradually used fingerprints as one of the methods for identifying criminals. With the advancement of technology, the use of various electronic devices to achieve real-time identity authentication requirements has become an important issue at present, such as network authentication, access control authentication, smartphone security authentication, and so on.

At present, the technology can be mainly divided into two methods of capacitive and optical to identify the lines on the fingerprint. Among them, the capacitive type uses a semiconductor chip sensor (Semiconductor Sensor) to sense fingerprints. The principle is to integrate a high-density electrode array into a chip. When the user performs fingerprint recognition, he presses his finger on the fingerprint On the surface of the chip, the difference in capacitance between the fingerprint ridges, valleys and the opposing electrode array on the chip is identified to complete the fingerprint texture image capture. Capacitive fingerprint recognition technology has the advantages of miniaturization and thinness, and can be widely used in handheld electronic devices, but it has the problems of high cost and poor sensitivity.

The optical design is earlier than the capacitive type. The 1970s optical fingerprint identification architecture used Sanyin, light source, and photosensitive elements to record fingerprints. When fingerprinting, it pressed the finger on Sanyin, and The reflection of the light source allows the ridge of the fingerprint of the finger to be displayed, and finally, the image is intercepted through the photosensitive element. Since the optical fingerprint collection method is not in contact with the chip itself, it is mainly composed of optical elements such as glass or acrylic. Therefore, compared with the capacitive type, the structure is simple and the hardware price is low.

The main purpose of the present invention is to improve the disadvantages of the conventional fingerprint identification module, such as high cost, poor sensitivity, and high assembly difficulty. In order to achieve the above object, the present invention adopts the following technical means to achieve it. Among them, the present invention provides a light guide element applied to an optical sensor. The light guide element is a transparent three-dimensional structure, which includes: a first The surface, a plurality of semi-transmissive and semi-reflective films and a second surface. The first surface corresponds to an object to be measured. A plurality of semi-transmissive and semi-reflective films are disposed inside the light guide element, the semi-transparent and semi-reflective films are parallel to each other, and there is an extension direction between the semi-transparent and semi-reflective interfaces and the first surface An angle. The second surface includes a light guiding area, and the position of the light guiding area corresponds to the optical sensor. Wherein, when the optical sensor projects an incident light into the light guide element through the light guiding area, the incident light is diffused through the semi-transmissive and semi-reflective films to the entire first surface, along the first surface A normal direction of is emitted to the object to be measured to generate a reflected light, and the reflected light is then guided through the semi-transmissive and semi-reflective films to the light guide area and along a normal direction of the second surface The injection enters the optical sensor.

In an embodiment of the invention, the included angle is between 41 degrees and 49 degrees.

In an embodiment of the invention, the material of the light guide element includes glass or polymethyl methacrylate.

In an embodiment of the invention, the second surface further includes a light absorbing layer coated on the periphery of the light guiding area.

In an embodiment of the invention, the light guide element further includes a reflective film disposed at the tail end of the transflective films and parallel to the transflective films.

In an embodiment of the invention, the side of the light guide element includes a light absorbing layer.

In an embodiment of the invention, the transflective film is a metal coating, the metal coating includes silver, aluminum, or nickel-chromium alloy, and the thickness of the metal coating is between 20 and 90 angstroms.

In an embodiment of the invention, the transflective film is a multilayer dielectric film.

In an embodiment of the invention, the multilayer dielectric film includes a zinc sulfide film and a magnesium fluoride film.

In order to achieve the above objectives and effects, the technical means and structure adopted by the present invention, the drawings and details of an embodiment of the present invention are described in detail below. The features and functions are as follows. Poli fully understands, but it should be noted that the content does not constitute Limitation of the invention.

Please refer to FIGS. 1 and 2, which are a schematic perspective view and a schematic cross-sectional view of an embodiment of a light guide element of the present invention. The light guide element 1 of the present invention can be applied to an optical fingerprint recognition module of a smart device, and is used in conjunction with an optical sensor 2. The optical sensor 2 is used to emit an incident signal and detect the reflected signal returned by the incident signal. It may include a sensor 21 and a light source 22. The light guide element 1 is a transparent three-dimensional structure, which includes: a first surface 11, a plurality of semi-transmissive and semi-reflective films 13 and a second surface 12.

The first surface 11 corresponds to an object to be tested, and the object to be tested is an object that needs to be recognized, such as a finger fingerprint of a human body. Among them, the first surface 11 and the object to be measured may further include a display element 5, a display panel or a protective cover of the smart device that does not affect the fingerprint recognition function.

The semi-transmissive and semi-reflective film 13 is disposed inside the light guide element 1 and has the characteristics of light transmission and reflection at the same time. The transflective films 13 are parallel to each other, and there is an angle θ between the transflective interfaces and an extending direction 91 of the first surface 11. The angle θ is between 41 degrees and 49 degrees. In an embodiment of the invention, the angle θ is 45 degrees. Wherein, the light guide element 1 further includes a reflective film 14 disposed at the tail end of the semi-transmissive semi-reflective films 13 and parallel to the semi-transparent semi-reflective films 13.

In an embodiment of the invention, the transflective film 13 is a metal coating, the metal coating includes silver, aluminum, or nickel-chromium alloy, and the thickness of the metal coating is between 20 and 90 Angstroms (Angstrom )between.

In another embodiment of the invention, the transflective film 13 is a multilayer dielectric film. In one embodiment, the multilayer dielectric film includes a zinc sulfide film and a magnesium fluoride film. The number of layers of the multilayer dielectric film can be determined according to the effect requirements. In an embodiment of the invention, the multilayer dielectric film has a three-layer film structure of zinc sulfide, magnesium fluoride, and zinc sulfide. In another embodiment of the present invention, the multilayer dielectric film has a four-layer film structure of zinc sulfide, magnesium fluoride, zinc sulfide, and magnesium fluoride. In yet another embodiment of the present invention, the multilayer dielectric film has a five-layer film structure of magnesium fluoride, zinc sulfide, magnesium fluoride, zinc sulfide, and magnesium fluoride.

The second surface 12 includes a light guiding area 121, and the position of the light guiding area 121 corresponds to the optical sensor 2, and the optical sensor 2 and the second surface 12 are separated by a distance H.

Please also refer to FIG. 3, which is a schematic diagram of incident signals of an embodiment of the light guide element of the present invention. Through the above structure, the light source 22 can project an incident light 41 into the light guide element 1 through the light guide area 121. Due to the relationship of the semi-transmissive and semi-reflective film 13, a part of the incident light 41 will penetrate The semi-transmissive and semi-reflective film 13 reaches the first surface 11, and another part of the incident light 41 is reflected on the other semi-transparent and semi-reflective film along the extending direction 91, repeating the process of semi-transmissive and semi-reflective, Until the reflective film 14 is fully reflected to the first surface 11, the incident light 41 is diffused to the entire first surface 11 and emitted along a normal direction 92 of the first surface 11 to the light guide The object 3 to be measured above the element 1. Please also refer to FIG. 4, which is a schematic diagram of reflected signals of an embodiment of the light guide element of the present invention. At this time, the object to be measured 3 generates a reflected light 42 based on the incident light 41, and then the reflected light 42 is guided through the semi-transmissive semi-reflective films 13 through the above-mentioned method and based on the principle that the incident angle is equal to the reflection angle The light is guided to the light guide area 121 and is emitted into the sensor 21 along the normal direction 92 of the second surface 12 and is sensed by the sensor 21.

In an embodiment of the invention, the second surface 12 further includes a light absorbing layer 122 coated on the periphery of the light guiding area 121. And, the side of the light guide element 1 includes another light absorbing layer 15. In the present invention, a light absorption layer is provided on the second surface 12 and the side surface of the light guide element 1 to absorb the light scattered during the reflection of the reflected light 42 from the object to be measured 3 to the sensor 21 to avoid the influence of the scattered light The accuracy of the optical signal.

In an embodiment of the invention, the light source 22 is an infrared light source (Infrared, IR). Infrared has better short-distance signal transmission applications, and is suitable as a sensing signal for fingerprint identification.

In an embodiment of the invention, the material of the light guide element 1 includes a light transparent material such as glass or polymethyl methacrylate.

Please refer to FIG. 5, which is a schematic diagram of a light guide element according to a second embodiment of the light guide element of the present invention. The second embodiment of the present invention discloses a light guide element 1a, the structure of which includes a plurality of transparent triangular pillars, and the inclined surfaces of the transparent triangular pillars can be first semi-transmitted and semi-reflective coated to make a semi-transparent semi-reflective film 13a, and then The inclined surfaces of the two transparent triangular columns are combined to form a single individual 10a, and finally each individual 10a is bonded to a columnar structure using an adhesive material, and the single individuals 10a at both ends can be respectively provided with a reflective film 14a and a light absorbing layer 15a . The refractive index of the adhesive material is close to the refractive index of the triangular column. Through the above method, the light emitted by the optical sensor can also enter the light guide element 1a through the light guide area 121a of the second surface 12a, and after the semi-transmissive reflection diverges to the object to be measured, the reflection from the object to be measured Light will also be guided through the semi-transmissive and semi-reflective films 13a to the light guiding area 121a and exit to the optical sensor.

In the second embodiment of the present invention, the second surface 12a may also include a light absorbing layer 122a coated on the periphery of the light guiding area 121a to absorb light scattered by the reflected light 42 in the reflection path.

Through the above detailed description, it can be fully shown that the purpose and effectiveness of the present invention are progressive in implementation, extremely useful for the industry, and are new inventions that have never been seen on the market, and fully meet the requirements of the invention patent , Xuan filed an application in accordance with the law. However, the above is only an example of the present invention, which does not limit the implementation and protection scope of the present invention. Those skilled in the art should be able to realize the equivalence made by using the description and illustration content of the present invention. The solutions obtained by replacement and obvious changes should be included in the protection scope of the present invention.

1,1a‧‧‧Light guide element 10a‧‧‧individual 11,11a‧‧‧First surface 12,12a‧‧‧Second surface 121,121a‧‧‧Light guide area 122,122a‧‧‧Light absorption layer 13,13a‧‧‧ Semi-transmissive and semi-reflective film 14,14a‧‧‧Reflective film 15,15a‧‧‧Light absorption layer 2‧‧‧Optical sensor 21‧‧‧Sensor 22‧‧‧Light source 3‧‧‧Object to be measured 41‧‧‧incident light 42‧‧‧Reflected light 5‧‧‧Display element 91‧‧‧Extending direction 92‧‧‧Normal direction θ‧‧‧ included angle H‧‧‧Distance

FIG. 1 is a schematic perspective view of an embodiment of a light guide element of the present invention. 2 is a schematic cross-sectional view of an embodiment of a light guide element of the present invention. FIG. 3 is a schematic diagram of incident signals of an embodiment of a light guide element of the present invention. 4 is a schematic diagram of a reflected signal of an embodiment of a light guide element of the present invention. 5 is a schematic structural diagram of a second embodiment of a light guide element of the present invention.

1‧‧‧Light guide element

11‧‧‧ First surface

12‧‧‧Second surface

121‧‧‧Light guide area

122‧‧‧Light absorption layer

13‧‧‧ Semi-transmissive and semi-reflective film

14‧‧‧Reflective film

15‧‧‧Light absorption layer

2‧‧‧Optical sensor

21‧‧‧Sensor

22‧‧‧Light source

5‧‧‧Display element

91‧‧‧Extending direction

92‧‧‧Normal direction

θ‧‧‧ included angle

Claims (7)

A light guide element includes: a first surface corresponding to an object to be measured; a plurality of semi-transmissive semi-reflective films are disposed inside the light guide element, the semi-transparent semi-reflective films are parallel to each other, and the There is an angle between the semi-transmissive and semi-reflective interface and an extension direction of the first surface; and a second surface includes a light guiding area, the position of the light guiding area corresponds to an optical sensor, the optical The sensor is used to emit incident signals and detect reflected signals returned by the incident signals. The optical sensor includes a sensor and a light source, wherein the second surface further includes a light absorbing layer coated on the light In the periphery of the guiding area, the side of the light-guiding element includes a light-absorbing layer. The light-guiding element further includes a reflective film disposed at the end of the semi-transmissive semi-reflective films and The reflective films are parallel to each other, and the optical sensor is at a distance from the second surface of the light guide element. When the optical sensor projects an incident light into the light guide element through the light guide area, the incident light passes through the The semi-transmissive and semi-reflective films spread to the entire first surface, and are emitted to the object to be measured along a normal direction of the first surface to generate a reflected light. The reflected light then passes through the semi-transmissive and semi-reflective films The light is guided to the light guide area, and is emitted into the optical sensor along a normal direction of the second surface. The light guide element as described in item 1 of the patent application range, wherein the included angle is between 41 degrees and 49 degrees. The light guide element as described in item 1 of the patent application scope, wherein the material of the light guide element includes glass or polymethyl methacrylate. The light guide element as described in item 1 of the patent application scope, wherein the semi-transmission and semi-reflection The thin film is a metal coating, the metal coating includes silver, aluminum or nickel-chromium alloy, and the thickness of the metal coating is between 20 and 90 angstroms. The light guide element as described in item 1 of the patent application range, wherein the transflective film is a multilayer dielectric film. The light guide element as described in item 5 of the patent application range, wherein the multilayer dielectric film includes a zinc sulfide film and a magnesium fluoride film. A light guide element, the structure of which includes a plurality of transparent triangular pillars, any two inclined surfaces of the transparent triangular pillars are combined into a single individual, and finally each individual is bonded to a cylindrical structure using adhesive glue, including: a first surface, Corresponding to an object to be measured; a plurality of semi-transmissive semi-reflective films are arranged inside the light guide element, the semi-transparent semi-reflective films are parallel to each other, and the semi-transmissive semi-reflective interfaces and the first surface There is an angle between an extension direction; and a second surface, including a light guide area, the position of the light guide area corresponds to an optical sensor, the optical sensor is used to emit incident signals and detect the incident The reflected signal returned by the signal, the optical sensor includes a sensor and a light source, wherein the second surface further includes a light absorbing layer coated on the periphery of the light guide area, on the side of the light guide element It includes a light absorbing layer, the light guide element further includes a reflective film, disposed at the tail end of the semi-transmissive semi-reflective films, and parallel to the semi-transparent semi-reflective films, the optical sensor and the The second surface of the light guide element is separated by a distance, and when the optical sensor projects an incident light into the light guide element through the light guide area, the incident light is diffused through the semi-transmissive and semi-reflective films to the entire first A surface, which is emitted to the object to be measured along a normal direction of the first surface to generate a reflected light, the reflected light It is then guided through the semi-transmissive and semi-reflective films to the light guiding area, and is emitted into the optical sensor along a normal direction of the second surface.

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