TW201942604A - Optical identification module - Google Patents

Abstract

An optical identification module including a cover plate, a sensor, a display panel, a first polarizer, and a second polarizer is provided. The display panel is disposed between the cover plate and the sensor. The first polarizer is disposed between the cover plate and the display panel. The first polarizer is a circular polarizer or a linear polarizer. The second polarizer is disposed between the display panel and the sensor. The second polarizer is a circular polarizer or a linear polarizer.

Description

Optical identification module

The invention relates to an optical module, and in particular to an optical identification module capable of recognizing biological characteristics.

With the rapid development of the Internet of Things technology, the application and demand of biometric technology have therefore expanded rapidly. At present, common biometric technologies on the market mainly use fingerprint, palm print, vein distribution, iris, retina, or facial features to identify biological features such as optical, capacitive, or ultrasonic methods, so as to achieve identity recognition or authentication. Compared with a recognition module that recognizes a biometric feature in a capacitive or ultrasonic manner, an optical recognition module that optically recognizes a biometric feature uses a sensor to receive a light beam reflected by the object to be tested for biometric recognition. It has the advantages of high durability and low cost. However, the beam may be transmitted to the sensor without the action of the object due to the interface reflection during the transmission toward the object to be measured, resulting in a low signal-to-noise ratio and affecting the recognition accuracy. . In addition, external ambient light may also enter the optical identification module and pass to the sensor, causing optical crosstalk. Therefore, how to improve the signal-to-noise ratio has become one of the problems that researchers in this field want to solve.

The invention provides an optical identification module, which has good identification accuracy.

An optical identification module of the present invention includes a cover plate, a sensor, a display panel, a first polarizer, and a second polarizer. The display panel is disposed between the cover and the sensor. The first polarizer is disposed between the cover plate and the display panel. The first polarizer is a circular polarizer or a linear polarizer. The second polarizer is disposed between the display panel and the sensor. The second polarizer is a circular polarizer or a linear polarizer.

In an embodiment of the present invention, the display panel is an organic light emitting display panel or a micro light emitting diode display panel.

In one embodiment of the present invention, the first polarizer and the second polarizer are both right-handed polarizers or both left-handed polarizers.

In an embodiment of the present invention, the first polarizer includes a first linear polarizer and a first quarter wave plate, and the first quarter wave plate is disposed between the first linear polarizer and the display panel. . The second polarizer includes a second linear polarizer and a second quarter wave plate, and the second quarter wave plate is disposed between the second linear polarizer and the display panel, or the second linear polarizer is disposed between Between the second quarter wave plate and the display panel.

In an embodiment of the present invention, the first polarizer and the second polarizer are both linear polarizers, and the included angle between the penetration axis of the first polarizer and the penetration axis of the second polarizer is 0 degrees. To 45 degrees.

In an embodiment of the invention, the optical identification module further includes a band-pass filter. The band-pass filter is suitable for filtering infrared light, and the band-pass filter is arranged on the sensor.

In an embodiment of the invention, the optical identification module further includes a band-pass filter. The band-pass filter is suitable for filtering a part of visible light, and the band-pass filter is disposed between the display panel and the sensor.

In an embodiment of the invention, the optical identification module further includes a collimator. The collimator is disposed between the display panel and the sensor.

In an embodiment of the invention, the optical identification module further includes a quarter wave plate. A quarter wave plate is disposed between the second polarizer and the collimator.

In an embodiment of the invention, the optical identification module further includes at least one anti-reflection layer. The at least one anti-reflection layer is disposed on at least one surface of at least one of a display panel, a first polarizer, a second polarizer, a collimator, and a quarter wave plate.

In an embodiment of the invention, the optical identification module further includes a light source. The light source is located next to the sensor.

Based on the above, in the optical recognition module of the present invention, the first polarizer and the second polarizer are used to reduce the light intensity of the light beam transmitted to the sensor without the action of the object to be measured, so as to improve the noise. ratio. Therefore, the optical recognition module of the present invention can have good recognition accuracy.

In order to make the above features and advantages of the present invention more comprehensible, embodiments are hereinafter described in detail with reference to the accompanying drawings.

In the drawings, each drawing illustrates a general feature of a method, structure, and / or material used in a particular exemplary embodiment. However, the drawings are not limited to the structures or features of the following embodiments, and the drawings should not be construed to define or limit the scope or nature covered by the exemplary embodiments. For example, for clarity, the relative thickness and position of each film layer, region and / or structure may be reduced or enlarged.

The use of similar or identical element symbols in the various drawings tends to indicate the presence of a similar or identical element or feature. Similar element symbols in the drawings indicate similar elements and their detailed description will be omitted.

The optical recognition module listed in the following embodiments is suitable for capturing biological characteristics of the object to be measured. The test object can be a finger or a palm. Correspondingly, the biological feature may be a fingerprint, a vein, or a palm print, but is not limited thereto.

1 to 9 are schematic cross-sectional views of optical identification modules according to the first to ninth embodiments of the present invention, respectively. Referring to FIG. 1, the optical recognition module 100 of the first embodiment includes a cover plate 110, a sensor 120, a display panel 130, a first polarizer 140 and a second polarizer 150.

The cover plate 110 is adapted to protect elements located thereunder. For example, the cover plate 110 may be a strengthened or unreinforced glass substrate, but is not limited thereto.

The sensor 120 is adapted to receive a light beam (ie, a light beam with biometric information, such as a light beam BO) reflected by the object under test OBJ. For example, the sensor 120 may include a Charge Coupled Device (CCD), a Complementary Metal-Oxide Semiconductor (CMOS), or other suitable types of optical sensing devices.

The display panel 130 is disposed between the cover 110 and the sensor 120. The display panel 130 is adapted to provide visible light B. In this embodiment, the visible light B provided by the display panel 130 can be used for biometric identification in addition to display. For example, the display panel 130 is an organic light emitting display panel or a micro light emitting diode display panel, but is not limited thereto.

The first polarizer 140 is disposed between the cover plate 110 and the display panel 130. The second polarizer 150 is disposed between the display panel 130 and the sensor 120. In other words, the first polarizer 140 and the second polarizer 150 are located on opposite sides of the display panel 130, respectively.

The first polarizer 140 may be a circular polarizer or a linear polarizer. The second polarizer 150 may be a circular polarizer or a linear polarizer. In this embodiment, the first polarizer 140 and the second polarizer 150 are both circular polarizers, and the first polarizer 140 and the second polarizer 150 can be both right-handed polarizers or left-handed polarizers.

In detail, the first polarizer 140 includes a first linear polarizer 142 and a first quarter wave plate 144, and the first quarter wave plate 144 is disposed between the first linear polarizer 142 and the display panel 130. between. The second polarizer 150 includes a second linear polarizer 152 and a second quarter wave plate 154, and the second quarter wave plate 154 is disposed between the second linear polarizer 152 and the display panel 130.

A part of the visible light B provided by the display panel 130 (such as the light beam B1) is sequentially transmitted to the object to be measured OBJ through the first quarter wave plate 144, the first linear polarizing plate 142, and the cover plate 110. The light beam reflected by the object under test OBJ (that is, the light beam BO with biometric information) passes through the cover plate 110, the first linear polarizer 142, the first quarter wave plate 144, the display panel 130, and the second The half-wave plate 154 and the second linear polarizer 152 are transmitted to the sensor 120. However, in addition to the light beam BO with biometric information, the sensor 120 may also receive light beams, such as light beams BR2 and BR3, which have not been acted upon (such as reflected) by the object to be measured OBJ. In detail, a part of the visible light B provided by the display panel 130 (such as the light beams B2 and B3) may be turned due to the interface reflection during the transmission to the object OBJ. For example, the light beams B2 and B3 are transmitted to the first line The polarizing plate 142 and the first quarter-wave plate 144 are turned by the interface reflection, and the light beams BR2 and BR3 turned by the interface reflection are then transmitted to the sensor 120 and finally received by the sensor 120.

The light intensity of the light beams BR2 and BR3 is extremely strong. In the structure without the second polarizer 150, the sensor 120 may receive 100% of the light beams BR2 and BR3, and affect the recognition accuracy. With the design of the first polarizer 140 and the second polarizer 150, the light beams BR2 and BR3 received by the sensor 120 can be reduced to about 50%, and the biometric information received by the sensor 120 with biometric information can be reduced. The beam BO is maintained at about 100%.

In detail, the visible light B provided by the display panel 130 is unpolarized light itself. That is, the visible light B provided by the display panel 130 has a first polarization direction P1 and a second polarization direction P2. The portion of visible light B that passes through the first linear polarizer 142 (see beam B1) will change from unpolarized light to linearly polarized light, and the polarization direction of the linearly polarized light (such as the first polarization direction P1) is parallel to the first linear polarization The penetration axis of the sheet 142 (not shown). The linearly polarized light has the same polarization direction after being reflected by the OBJ. The linearly polarized light passes through the first quarter-wave plate 144 and becomes circularly polarized light (such as left-handed polarized light). The circularly polarized light passes through the second quarter-wave plate 154 and returns to linearly polarized light, and the polarization direction of the linearly polarized light is parallel to the transmission axis of the second linearly polarized plate 152. Therefore, the linearly polarized light can pass through the second linearly polarizing plate 152 and be received by the sensor 120. In other words, the light beam reflected by the object under test OBJ (ie, the light beam BO with biometric information) is almost 100% received by the sensor 120. On the other hand, portions of the visible light B that do not pass through the first linear polarizer 142 (such as the light beams B2 and B3) are turned by the interface reflection, and the light beams BR2 and BR3 turned by the interface reflection are still unpolarized light. Of the unpolarized light, only the light beam whose polarization direction is parallel to the transmission axis of the second linear polarizer 152 (that is, the light beam having the first polarization direction P1) can pass through the second linear polarizer 152 and be received by the sensor 120. In other words, about 50% of the light beam BR2 (or light beam BR3) turned by the interface reflection is filtered by the second linear polarizer 152 and about 50% passes through the second linear polarizer 152 and is received by the sensor 120.

The first polarizer 140 and the second polarizer 150 are used to reduce the light intensity of the light beams (such as the light beams BR2 and BR3) transmitted to the sensor 120 without the object OBJ, so as to improve the signal-to-noise ratio. Therefore, the optical recognition module 100 can have good recognition accuracy.

According to different needs, the optical identification module 100 may optionally include other elements or films. The following embodiments can all be improved with this, which will not be described in detail below.

Please refer to FIG. 2A. The main differences between the optical identification module 100A1 of the second embodiment and the optical identification module 100 of FIG. 1 are as follows. In the optical identification module 100A1, the second linear polarizer 152 is disposed between the second quarter-wave plate 154 and the display panel 130.

Please refer to FIG. 2B. The main differences between the optical identification module 100A2 and the optical identification module 100A1 of FIG. 2A are as follows. In the optical identification module 100A2, the second polarizer 150A is a linear polarizer. Further, the second polarizer 150A includes a second linear polarizer 152 but does not include the second quarter-wave plate 154 of FIG. 2A. Under the influence of some non-ideal characteristics, the light beam BO (not shown in FIG. 2B, see FIG. 1) with biometric information will be elliptically polarized, so the second polarizer 150A is a linear polarizer, which allows greater than 50% For example, 70%) of the light beam BO passes. On the other hand, only 50% of the light beams (such as the light beams BR2 and BR3 in FIG. 1) that have not been tested (such as reflection) can pass through. Therefore, the signal-to-noise ratio can be improved.

Please refer to FIG. 3. The main differences between the optical identification module 100B of the third embodiment and the optical identification module 100 of FIG. 1 are as follows. In the optical identification module 100B, the first polarizer 140A and the second polarizer 150A are both linear polarizers. Further, the first polarizer 140A includes the first linear polarizer 142 but does not include the first quarter wave plate 144 of FIG. 1, and the second polarizer 150A includes the second linear polarizer 152 but does not include FIG. 1. The second quarter wave plate 154. In addition, the included corner between the transmission axis of the first polarizer 140A and the transmission axis of the second polarizer 150A is in a range of 0 degrees to 45 degrees. In other words, the included angle between the transmission axis of the first polarizer 140A and the transmission axis of the second polarizer 150A may be greater than or equal to 0 degrees and less than or equal to 45 degrees.

Under this architecture, the beam reflected by the object under test OBJ (ie, the beam BO with biometric information) passes through the first linear polarizer 142 and before it passes through the second linear polarizer 152. Polarization direction P1. The light beam reflected by the object under test OBJ (ie, the light beam BO with biometric information) is almost 100% received by the sensor 120. On the other hand, the portion of the visible light B that does not pass through the first linear polarizer 142 (such as the light beam B2) is turned by the interface reflection, and the light beam BR2 turned by the interface reflection is still unpolarized light. Of the unpolarized light, only the light beam whose polarization direction is parallel to the transmission axis of the second linear polarizer 152 (that is, the light beam having the first polarization direction P1) can pass through the second linear polarizer 152 and be received by the sensor 120. Therefore, about 50% of the light beam BR2 turned by the interface reflection is filtered by the second linear polarizer 152 and about 50% passes through the second linear polarizer 152 and is received by the sensor 120.

The first polarizer 140A and the second polarizer 150A are used to reduce the light intensity of the light beam (such as the light beam BR2) transmitted to the sensor 120 without the object OBJ, so as to improve the signal-to-noise ratio. Therefore, the optical recognition module 100B can have good recognition accuracy.

Please refer to FIG. 4. The main difference between the optical identification module 100C of the fourth embodiment and the optical identification module 100 of FIG. 1 is that the optical identification module 100C further includes a band-pass filter 160. The band-pass filter 160 is suitable for filtering optical interference caused by external ambient light, and the penetration spectrum of the band-pass filter 160 may be determined according to a band used for biometric identification. For example, if biometric recognition is performed by visible light, the band-pass filter 160 may be an IR cut filter that filters infrared light, and the band-pass filter 160 may be disposed on the sensor 120. Either position. As shown in FIG. 4, the band-pass filter 160 may be disposed between the cover plate 110 and the first polarizer 140. However, the band-pass filter 160 may be disposed on the cover plate 110, and the band-pass filter 160 may also be disposed between the first polarizer 140 and the display panel 130, between the display panel 130 and the second polarizer 150, or the first polarizer 140. Between the two polarizers 150 and the sensor 120. On the other hand, if biometric identification is performed by using only a part of visible light (that is, selecting a band from 400 nm to 700 nm for biometric identification), the band-pass filter 160 may filter part of visible light (that is, filter 400 nm to 700). (not used for biometric identification in nm), and the band-pass filter 160 may be disposed between the display panel 130 and the sensor 120, for example, between the display panel 130 and the second polarizer 150 or the first Between the two polarizers 150 and the sensor 120.

Please refer to FIG. 5. The main difference between the optical identification module 100D of the fifth embodiment and the optical identification module 100B of FIG. 3 is that the optical identification module 100D further includes a band-pass filter 160. For related descriptions of the band-pass filter 160, please refer to the foregoing, and will not be repeated here.

Please refer to FIG. 6. The main difference between the optical identification module 100E of the sixth embodiment and the optical identification module 100C of FIG. 4 is that the optical identification module 100E further includes a collimator 170. The collimator 170 is disposed between the display panel 130 and the sensor 120, and the collimator 170 is adapted to collimate the light beam reflected by the object to be measured (not shown in FIG. 6) and transmitted toward the sensor 120. . The collimator 170 may employ any known light collimation element. For example, the collimator 170 may include an optical fiber array, a light-shielding element having a through hole, or a light-transmitting substrate with a light-shielding layer having an opening formed on the surface, and the like.

It should be noted that the optical identification module 100 of FIG. 1, the optical identification module 100A of FIG. 2A, the optical identification module 100A of FIG. 2B, the optical identification module 100B of FIG. 3, and the optical identification module 100D of FIG. A collimator 170 may be further included as required.

Please refer to FIG. 7. The main difference between the optical identification module 100F of the seventh embodiment and the optical identification module 100E of FIG. 6 is that the optical identification module 100F further includes a quarter wave plate 180, and the quarter wave plate 180 is disposed between the second polarizer 150 and the collimator 170. The quarter-wave plate 180 is suitable for filtering the light beam (such as the beam BR) which is turned by the interface reflection between the second polarizer 150 and the collimator 170, and helps to prevent stray light (such as the beam BR) from being transmitted to In the eyes of the user.

Further, the beam reflected by the object under test OBJ (ie, the beam BO with biometric information) may be reflected by the interface between the second polarizer 150 and the collimator 170 during the transmission toward the sensor 120. . Under the structure in which the quarter wave plate 180 is provided, the light beam BO passes from the second linear polarizer 152 and changes from circularly polarized light (such as left-handed polarized light) to linearly polarized light (having a first polarization direction P1; not shown) After the linearly polarized light passes through the quarter-wave plate 180, it will change from linearly polarized light to circularly polarized light (such as left-handed polarized light). Circularly polarized light (such as left-handed polarized light) is reflected by the collimator 170 and turned (for example, from left-handed polarized light to right-handed polarized light). The turned circularly polarized light (such as right-handed polarized light) passes through the quarter-wave plate 180 and becomes linearly polarized light (having a second polarization direction P2). Since the second polarization direction P2 is perpendicular to the transmission axis of the second linear polarizer 152, the linearly polarized light is filtered by the second linear polarizer 152.

It should be noted that the optical identification module 100 of FIG. 1, the optical identification module 100A of FIG. 2A, the optical identification module 100A of FIG. 2B, the optical identification module 100B of FIG. 3, and the optical identification module 100D of FIG. As required, at least one of the collimator 170 and the quarter-wave plate 180 may be further included.

Please refer to FIG. 8. The main difference between the optical identification module 100G of the eighth embodiment and the optical identification module 100F of FIG. 7 is that the optical identification module 100G further includes at least one anti-reflection layer 190 to reduce interface reflection. As shown in FIG. 8, the optical identification module 100G may include an anti-reflection layer 190, and the anti-reflection layer 190 may be disposed on a surface of the collimator 170 facing the quarter wave plate 180, but is not limited thereto. The anti-reflection layer 190 may also be disposed on a surface of the collimator 170 facing the sensor 120. Alternatively, the anti-reflection layer 190 may be disposed on one surface of one of the display panel 130, the first polarizer 140, the second polarizer 150, and the quarter-wave plate 180. Furthermore, the optical recognition module 100F may include a plurality of anti-reflection layers 190, and the plurality of anti-reflection layers 190 may be disposed on the display panel 130, the first polarizer 140, the second polarizer 150, the collimator 170, and On multiple surfaces in the quarter wave plate 180.

It should be noted that the optical identification module 100 of FIG. 1, the optical identification module 100A of FIG. 2A, the optical identification module 100A of FIG. 2B, the optical identification module 100B of FIG. 3, and the optical identification module 100D of FIG. According to requirements, at least one of a collimator 170, a quarter wave plate 180, and at least one anti-reflection layer 190 may be further included.

Please refer to FIG. 9. The main difference between the optical identification module 100H of the ninth embodiment and the optical identification module 100G of FIG. 8 is that the optical identification module 100H further includes a light source LS. The light source LS is disposed beside the sensor 120, and the light source is adapted to provide a light beam for biometric identification. Under the structure provided with the light source LS and the band-pass filter 160, the transmission spectrum of the band-pass filter 160 corresponds to the spectrum of the light beam emitted by the light source LS. For example, the light source LS is an infrared light source, and the band-pass filter 160 is an infrared cut-off filter, but it is not limited thereto.

It should be noted that the optical identification module of the foregoing embodiments may further include a light source LS according to requirements.

In summary, in the optical identification module of the present invention, the first polarizer and the second polarizer are used to reduce the light intensity of the light beam transmitted to the sensor without the object to be measured, so as to improve Signal to noise ratio. Therefore, the optical recognition module of the present invention can have good recognition accuracy. In an embodiment, a band-pass filter and / or a collimator may be further provided to improve optical interference. In another embodiment, a quarter-wave plate and / or at least one anti-reflection layer may be further provided to reduce the interface reflection. In yet another embodiment, a light source may be further provided.

Although the present invention has been disclosed as above with the examples, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field can make some modifications and retouching without departing from the spirit and scope of the present invention. The protection scope of the present invention shall be determined by the scope of the attached patent application.

100, 100A1, 100A2, 100B, 100C, 100D, 100E, 100F, 100G, 100H‧‧‧ Optical identification module

110‧‧‧ cover

120‧‧‧Sensor

130‧‧‧display panel

140, 140A‧‧‧first polarizer

142‧‧‧The first linear polarizer

144‧‧‧The first quarter wave plate

150, 150A‧‧‧Second polarizer

152‧‧‧Second linear polarizer

154‧‧‧The second quarter wave plate

160‧‧‧Band Pass Filter

170‧‧‧ Collimator

180‧‧‧ quarter wave plate

190‧‧‧Anti-reflective layer

B‧‧‧visible light

BO, BR, BR2, BR3, B1, B2, B3

LS‧‧‧Light source

OBJ‧‧‧DUT

P1‧‧‧first polarization direction

P2‧‧‧second polarization direction

1 to 9 are schematic cross-sectional views of optical identification modules according to the first to ninth embodiments of the present invention, respectively.

Claims (11)

An optical identification module includes: a cover plate; a sensor; a display panel disposed between the cover plate and the sensor; a first polarizer disposed between the cover plate and the display panel Wherein the first polarizer is a circular polarizer or a linear polarizer; and a second polarizer is disposed between the display panel and the sensor, wherein the second polarizer is a circular polarizer or a linear polarizer sheet. The optical identification module according to item 1 of the scope of patent application, wherein the display panel is an organic light emitting display panel or a micro light emitting diode display panel. The optical identification module according to item 1 of the patent application scope, wherein the first polarizer and the second polarizer are both right-handed polarizers or left-handed polarizers. The optical identification module according to item 3 of the patent application scope, wherein the first polarizer includes a first linear polarizer and a first quarter wave plate, and the first quarter wave plate is disposed at Between the first linear polarizer and the display panel, the second polarizer includes a second linear polarizer and a second quarter wave plate, and the second quarter wave plate is disposed in the first Between the second linear polarizer and the display panel, or the second linear polarizer is disposed between the second quarter wave plate and the display panel. The optical identification module according to item 1 of the scope of patent application, wherein the first polarizer and the second polarizer are both linear polarizers, and the transmission axis of the first polarizer and the second polarizer are The corners between the penetration axes are in the range of 0 degrees to 45 degrees. The optical identification module according to item 1 of the patent application scope further includes: a band-pass filter adapted to filter infrared light, and the band-pass filter is disposed on the sensor. The optical identification module according to item 1 of the patent application scope further includes: a band-pass filter adapted to filter part of visible light, and the band-pass filter is disposed between the display panel and the sensor. The optical identification module according to item 1 of the patent application scope further includes: a collimator disposed between the display panel and the sensor. The optical identification module according to item 8 of the scope of patent application, further comprising: a quarter-wave plate disposed between the second polarizer and the collimator. The optical identification module according to item 9 of the scope of patent application, further comprising: at least one anti-reflection layer disposed on the display panel, the first polarizer, the second polarizer, the collimator, and the quarter One of the wave plates is on at least one surface of at least one of them. The optical identification module according to item 1 of the patent application scope further includes: a light source, which is arranged beside the sensor.