CN211787124U - Biometric imaging apparatus and electronic apparatus - Google Patents
Biometric imaging apparatus and electronic apparatus Download PDFInfo
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- CN211787124U CN211787124U CN201922293211.XU CN201922293211U CN211787124U CN 211787124 U CN211787124 U CN 211787124U CN 201922293211 U CN201922293211 U CN 201922293211U CN 211787124 U CN211787124 U CN 211787124U
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Abstract
The present disclosure relates to a biometric imaging apparatus (100), characterized by comprising: an image sensor (102) comprising a plurality of pixels (104) forming a photodetector pixel array; a first aperture layer (106) comprising openings (108) in locations aligned with pixels of the pixel array; a first filter layer (110) comprising a transparent material configured to block light within a predetermined first wavelength range; a transparent spacer layer (112) disposed on the first filter layer, wherein the transparent spacer layer is configured to absorb light within a predetermined second wavelength range; and an array of microlenses (114) disposed on the transparent spacing layer, wherein the microlenses are aligned with the openings in the aperture layer. The present disclosure also relates to an electronic device comprising a display screen and the above biometric imaging device, the biometric imaging device being arranged below the display screen.
Description
Technical Field
The utility model relates to an optical biological identification imaging device suitable for integrated in display panel. In particular, the present invention relates to an optical biometric imaging device suitable for fingerprint sensing, wherein the sensing device comprises a plurality of microlenses.
Background
Biometric systems are widely used as a means to enhance the convenience and security of personal electronic devices such as mobile phones. At present, especially fingerprint sensing systems are included in most of all newly released consumer electronic devices, such as mobile phones.
Optical fingerprint sensors have been known for some time and in some applications may be a viable alternative to e.g. capacitive fingerprint sensors. The optical fingerprint sensor may be based, for example, on pinhole imaging principles and/or may employ micro-channels (i.e., collimators or micro-lenses) to focus incident light onto the image sensor.
US 2007/0109438 describes an optical imaging system that can be used as a fingerprint sensor, in which system a micro lens is arranged to redirect light onto a detector. In the described imaging system, each microlens constitutes a sampling point, and the microlenses are arranged close to each other to improve image resolution. To avoid mixing of light received from adjacent microlenses, a microchannel or aperture is arranged between the microlenses and the detector.
However, in order to achieve a high resolution sensor, the microlenses must be made small and must be manufactured with high precision, which makes the manufacturing process complex and sensitive to variations, and sensors of the type described comprising small microlenses will also be sensitive to spatial differences in transmission of any layer covering the sensor.
It is therefore desirable to provide an improved optical fingerprint sensing device.
SUMMERY OF THE UTILITY MODEL
In view of the above-mentioned and other drawbacks of the prior art, it is an object of the present invention to provide an improved biometric imaging device that is suitable for use under a display cover glass in an electronic user device.
According to a first aspect of the present invention, there is provided a biometric imaging apparatus, comprising: an image sensor comprising a plurality of pixels forming a photodetector pixel array; a first aperture layer comprising openings in locations aligned with pixels of the pixel array; a first filter layer comprising a transparent material configured to block light within a predetermined first wavelength range; a transparent spacer layer disposed on the first filter layer, wherein the transparent spacer layer is configured to absorb light within a predetermined second wavelength range; and a microlens array disposed on the transparent spacing layer, wherein the microlenses are aligned with the openings in the first aperture layer.
The first aperture layer is an opaque layer comprising openings for narrowing the light beam reaching the pixel, thereby reducing the field of view seen through each collimating structure, i.e. through each lens and aperture combination.
The first filter layer is preferably a layer that blocks light in the IR region, and the transparent material of the filter layer may thus be referred to as an IR cut-off material. Thus, the material is used as a filter, which is particularly important when the biometric imaging device is used in sunlight.
The microlenses may be arranged, for example, in a hexagonal or linear grid arrangement to form an array. Further, the microlens array may be formed as a single block, or may be formed as individual lenses arranged in an array.
According to an embodiment of the invention, the transparent spacer layer is a tinted glass layer. The tinted glass layer may also be referred to as a hybrid infrared cut filter, where the tinted glass is configured to absorb light in the infrared wavelength range and above so that visible light may reach the image sensor. The tinted glass layer may be obtained by incorporating an additive into the glass during the manufacturing process, wherein the additive may be phosphorus pentoxide (P)2O5) Or copper oxide (CuO). In addition, by controlling the kind and concentration of the additive, the light absorption characteristics of the colored glass layer can be controlled.
According to an embodiment of the invention, the transparent spacer layer shows a gradual increase of light absorption with increasing wavelength, so that visible light is transmitted and infrared light is absorbed. As described above, the absorption profile of the transparent spacing layer can be controlled and tailored by controlling the amount of additives in the layer.
According to an example embodiment of the present invention, the transparent spacer layer may have a transmittance in the range of 40% to 60% for wavelengths in the range of 600nm to 700nm, and wherein light having longer wavelengths is blocked. Thus, the transparent spacer layer acts as an infrared cut-off layer to reduce the amount of light in the infrared wavelength range that reaches the image sensor.
According to one embodiment of the present invention, the biometric imaging device further comprises a second filter layer comprising a transparent material configured to block light within the first wavelength range. The second filter layer helps to further reduce the amount of infrared light reaching the image sensor.
According to an embodiment of the invention, the first filter layer and the second filter layer are arranged on respective sides of the transparent spacer layer. By arranging the filter layers on respective sides of the tinted glass layer, respectively, the tension in the glass layer may be reduced, thereby reducing the risk of warping and bending of the transparent spacer layer.
According to one embodiment of the present invention, the biometric imaging device further comprises a second aperture layer comprising openings located in positions aligned with the pixels of the pixel array. The second aperture layer may, for example, be located above the first aperture layer, in which case the openings in the second aperture layer are larger than the openings in the first aperture layer. Thereby, stray light (stray light) can be reduced and crosstalk from neighboring lenses can be significantly reduced. An Optically Clear Adhesive (OCA) may be disposed between the first and second aperture layers to connect the layers and control the distance between the two aperture layers.
According to an embodiment of the present invention, the biometric imaging apparatus may further include a light blocking layer between adjacent microlenses. The light-blocking layer may be a layer arranged as a mask on the transparent spacer layer or on the second filter layer (if such a layer is used). The light blocking layer is configured to prevent light from reaching the imaging device without passing through the microlens. Therefore, the light blocking mask layer preferably covers the entire surface of the uppermost surface of the imaging device except for the positions of the microlenses. The light-blocking layer may also slightly overlap the microlens, which means that the opening in the light-blocking layer is smaller than the microlens.
Thereby, the amount of stray light reaching the image sensor that may disturb the captured image is reduced. In practice, some stray light may be allowable, but it is desirable to reduce the amount of optical "cross-talk" between pixels.
According to an embodiment of the present invention, the biometric imaging apparatus may further include a transparent base layer disposed between the microlens and the light blocking layer. The transparent base layer may be made of the same material as the microlenses and the base layer may also be in the same block as the microlenses, so that the entire microlens array supported by the base layer can be molded or stamped in one step.
According to an embodiment of the present invention, the first and second filter layers may be configured to block light having a wavelength greater than 550nm or 570nm, thereby serving as an infrared cut-off layer.
The first aperture layer may be a top metal layer in the image sensor. The image sensor may be manufactured using a CMOS process including a plurality of metal layers, and by using a top metal layer of the CMOS chip as an aperture layer, the manufacturing process of the biometric imaging device is simplified because an additional step for forming the aperture layer is not required.
The first aperture layer may also be disposed on the image sensor. The aperture layer is here provided as a separate layer arranged on the image sensor. An additional spacer layer may also be provided between the image sensor and the aperture layer.
According to an embodiment of the invention, the microlens is configured to have a focal point at a surface of the image sensor. Therefore, reflected light from a part of the biometric object that reaches one microlens is focused on the image sensor that can capture it.
The microlens may also be configured to have the focal point in the plane of an aperture layer that is located on or as part of the image sensor and directly over the pixels of the image sensor.
There is also provided an electronic device, comprising: a display screen; and a biometric imaging device according to any of the preceding embodiments, disposed below the display screen. Thus, the biometric imaging device may be integrated in or located below the display panel such that biometric imaging may be performed over the entire surface of the display. The pixels of the display will here be used as light sources for the biometric imaging sensor, so that the light emitted from the display panel is reflected by the biometric object in contact with the outer surface of the display panel and back towards the image sensor, wherein an image of the biometric object can be formed. The biometric object may be a fingerprint or a palm print, for example. Further, the electronic device may be a smartphone, a tablet computer, or the like.
Other features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled person realizes that different features of the present invention can be combined to produce embodiments other than those described hereinafter, without departing from the scope of the invention.
Drawings
These and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing exemplary embodiments of the invention, wherein:
fig. 1 schematically illustrates a biometric imaging system according to an embodiment of the present invention;
fig. 2 schematically illustrates a biometric imaging system according to an embodiment of the present invention; and
fig. 3 schematically illustrates a biometric imaging system according to an embodiment of the present invention.
Detailed Description
In this detailed description, various embodiments of a biometric imaging system in accordance with the present invention are described primarily with reference to a fingerprint imaging sensor that is adapted for use under a display panel of a consumer device, such as a smartphone, tablet computer, or the like.
Fig. 1 schematically illustrates a portion of a biometric imaging device 100. In particular, fig. 1 shows a cross-section of a portion of a biometric imaging device 100, and it should be understood that the imaging device is further extended to form a suitably sized imaging device.
The biometric imaging apparatus 100 includes: an image sensor 102, which in turn includes a plurality of pixels 104 forming a photodetector pixel array; and a first aperture layer 106 comprising openings 108 in locations aligned with the pixels 104 of the pixel array. Each opening 108 in the aperture layer 106 is aligned with a pixel 104 of the image sensor 102. However, the image sensor 102 may include more pixels than apertures, such that some of the pixels in the image sensor are not used.
The first aperture layer 106 may be formed from a topmost metal layer in a CMOS chip in which the image sensor 102 is formed. Thus, the image sensor 102 and the first aperture layer 106 may be formed in the same manufacturing process.
The biometric imaging apparatus 100 further includes: a first filter layer 110 comprising a transparent material 110 configured to block light within a predetermined first wavelength range; and a transparent spacer layer 112, here arranged on the first filter layer 110, wherein the transparent spacer layer 112 is configured to absorb light in a predetermined second wavelength range. In the biometric imaging device 100 shown in FIG. 1, the first filter layer 110 is located below the transparent spacer layer 112. However, first filter layer 110 may also be positioned on top of transparent spacer layer 112 as well, such that transparent spacer layer 112 is disposed on first aperture layer 106.
The first filter layer is preferably configured to block at least 50% of light having a wavelength greater than 570 nm. Thus, the first wavelength range comprises wavelengths larger than 570 nm.
Furthermore, the biometric imaging device 100 comprises an array of microlenses 114, where the array of microlenses 114 is arranged on the transparent spacing layer 112, wherein the microlenses 114 are aligned with the openings 118 in the first aperture layer 106. In embodiments where first filter layer 110 is disposed on top of transparent spacer layer 112, the microlens array would be disposed on first filter layer 110.
In the depicted embodiment, the transparent spacer layer 112 is a colored glass layer that exhibits a gradual increase in light absorption with increasing wavelength, such that visible light is transmitted and infrared light is absorbed. The purpose of the transparent spacer layer 112 is therefore to reduce the amount of infrared light reaching the image sensor.
The transparent spacer layer may for example have a transmission in the range of 40% to 60% for wavelengths in the range of 600nm to 700nm, and wherein light having longer wavelengths is blocked. Thus, the first wavelength range may be described as a wavelength range above 600 nm. The second wavelength range may also be the same as the first wavelength range.
The difference between the transparent spacing layer 112 and the first filter layer 110 is that: the transparent spacer layer 112 in the form of a tinted glass layer is configured to absorb infrared light, while the first filter layer 110 is configured to block infrared light. A filter layer configured to block light based on interference may have a sharp transmission curve as a function of wavelength, and transmission may also depend on the angle of incident light. In the light absorbing layer, the transition (transition) is smoother and has no angular dependence. Thus, by combining an absorbing layer with a barrier layer, the advantageous properties of the individual layers can be exploited.
The biometric imaging device 100 may also include additional intermediate layers not described herein, so long as the intermediate layers are sufficiently transparent to allow light to travel from the microlens to the image sensor without excessive loss.
Fig. 2 schematically illustrates a biometric imaging device 200, the biometric imaging device 200 further comprising a second aperture layer 208, the second aperture layer 208 comprising openings 210 in locations aligned with the pixels 104 of the pixel array. The opening 210 in the second aperture layer 208 is larger than the opening 108 in the first aperture layer so that the two aperture layers 106, 208 together act to narrow the light beam reaching the pixel 104. A transparent layer 206, which may be an Optically Clear Adhesive (OCA) layer, is disposed between the first aperture layer 106 and the second aperture layer 208 to define a distance between the layers 106 and 208.
The biometric imaging device 200 of fig. 2 also includes a second filter layer 202, the second filter layer 202 comprising a transparent material configured to block light in the first wavelength range. Thus, the characteristics of the second filter layer 202 are the same as the characteristics of the first filter layer 110. However, a second filter layer may be provided having different optical properties than the first filter layer.
In addition, the biometric imaging device 200 includes a light blocking layer 204 between adjacent microlenses 114. In other words, the light blocking layer 204 includes an opening at the position of the microlens 114. The light blocking layer 204 may be deposited on the device before or after the formation of the microlenses 114, and the light blocking layer 204 may in principle be located above the bottom plane of the lenses or in the same plane as the lenses. In either case, the opening of the light blocking layer 204 has a size equal to or smaller than the size of the microlens 114. The light blocking layer 204 also allows for a sparse arrangement of microlenses 114 in the microlens array such that there is a distance between adjacent microlenses 114. Thus, the light reaching the image sensor 102 necessarily passes through the microlens 114.
Fig. 3 schematically illustrates a biometric imaging sensor 300, the biometric imaging sensor 300 further comprising a transparent base layer 302, the transparent base layer 302 being disposed between the microlens 114 and the light blocking layer 204. The transparent base layer 302 may be made of the same material as the microlenses 114, and it may be formed as a single piece with the microlenses 114.
Other features of the biometric imaging devices 200, 300 of fig. 2 and 3 are similar to those described above with reference to the biometric imaging device 100 of fig. 1.
Even though the invention has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art. Further, it should be noted that portions of the device may be omitted, interchanged, or arranged in various ways, but the device is still capable of performing the functions of the invention.
Furthermore, variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
Claims (16)
1. A biometric imaging device (100) characterized by comprising:
an image sensor (102), the image sensor (102) comprising a plurality of pixels (104) forming a photodetector pixel array;
a first aperture layer (106), the first aperture layer (106) comprising openings (108) in locations aligned with pixels of the pixel array;
a first filter layer (110), the first filter layer (110) comprising a transparent material configured to block light within a predetermined first wavelength range;
a transparent spacer layer (112), wherein the transparent spacer layer is configured to absorb light within a predetermined second wavelength range; and
an array of microlenses (114), wherein the microlenses are aligned with the openings in the first aperture layer.
2. The biometric imaging apparatus of claim 1, wherein the transparent spacer layer is a tinted glass layer.
3. The biometric imaging apparatus of claim 1, wherein the transparent spacer layer exhibits a gradual increase in light absorption with increasing wavelength such that visible light is transmitted and infrared light is absorbed.
4. The biometric imaging apparatus of claim 1, wherein the transparent spacer layer has a transmittance in the range of 40% to 60% for wavelengths in the range of 600nm to 700nm, and wherein light having longer wavelengths is blocked.
5. The biometric imaging device of claim 1, further comprising a second filter layer (202), the second filter layer (202) comprising a transparent material configured to block light in the first wavelength range.
6. The biometric imaging apparatus of claim 5, wherein the first filter layer and the second filter layer are disposed on respective sides of the transparent spacer layer.
7. The biometric imaging device of claim 1, further comprising a second aperture layer (208), the second aperture layer (208) comprising openings (210) in locations aligned with pixels of the pixel array.
8. The biometric imaging device of claim 7, wherein the opening (210) in the second aperture layer is larger than the opening (108) in the first aperture layer.
9. The biometric imaging apparatus according to claim 1, further comprising a light blocking layer (204) between adjacent microlenses.
10. The biometric imaging apparatus according to claim 9, wherein the light blocking layer is disposed between adjacent microlenses such that light reaching the image sensor must pass through the microlenses.
11. The biometric imaging apparatus according to claim 9, further comprising a transparent substrate (302) disposed between the micro-lens and the light blocking layer.
12. The biometric imaging device of claim 1, wherein the first filter layer and the second filter layer are configured to block at least 50% of light having a wavelength greater than 570 nm.
13. The biometric imaging device of claim 1, wherein the aperture layer (106) is a top metal layer in the image sensor.
14. The biometric imaging device of claim 1, wherein the aperture layer (106) is disposed on the image sensor.
15. The biometric imaging apparatus of claim 1, wherein the microlens is configured to have a focal point at a surface of the image sensor.
16. An electronic device, comprising:
a display screen; and
the biometric imaging device as in claim 1, disposed below the display screen.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922293211.XU CN211787124U (en) | 2019-12-18 | 2019-12-18 | Biometric imaging apparatus and electronic apparatus |
| PCT/SE2020/051215 WO2021126058A1 (en) | 2019-12-18 | 2020-12-15 | Biometric imaging device and electronic device |
| EP20901866.2A EP4049175A4 (en) | 2019-12-18 | 2020-12-15 | Biometric imaging device and electronic device |
| US17/784,006 US20230020242A1 (en) | 2019-12-18 | 2020-12-15 | Biometric imaging device and electronic device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922293211.XU CN211787124U (en) | 2019-12-18 | 2019-12-18 | Biometric imaging apparatus and electronic apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN211787124U true CN211787124U (en) | 2020-10-27 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201922293211.XU Active CN211787124U (en) | 2019-12-18 | 2019-12-18 | Biometric imaging apparatus and electronic apparatus |
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| CN (1) | CN211787124U (en) |
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Effective date of registration: 20211208 Address after: Gothenburg Patentee after: Fingerprint kaana Kadun Intellectual Property Co.,Ltd. Address before: Gothenburg Patentee before: FINGERPRINT CARDS AB |