Signal reading method and reading device of a fingerprint imaging module

Abstract

A signal reading method and reading device of a fingerprint imaging module, the fingerprint imaging module comprising: a pixel array, the pixel array comprising a plurality of pixel groups, each pixel group comprising n pixel units, wherein n is an integer greater than 1; a microlens array, the microlens array being located on the pixel array, the microlens array comprising a plurality of microlenses; the microlenses corresponding to the pixel groups one by one; the signal reading method comprising: obtaining a group signal of a pixel group according to unit signals of m pixel units in the pixel group, wherein m is greater than or equal to 1 and less than n; and obtaining a fingerprint image according to group signals of a plurality of pixel groups. The technical scheme of the present application can realize full utilization of pixel units while the pixel units are closely adjacent to improve material area utilization, and image splicing is not required.

Description

Technical Field

[0001] This invention relates to the field of fingerprint recognition, and in particular to a signal readout method and readout device for a fingerprint imaging module. Background Technology

[0002] Fingerprint recognition technology captures images of a person's fingerprints using a fingerprint imaging module, then compares them with existing fingerprint images in the fingerprint recognition system to identify the individual. Due to its ease of use and the uniqueness of human fingerprints, fingerprint recognition technology has been widely applied in various fields, such as security checks in police stations and customs, building access control systems, and consumer products like personal computers and mobile phones.

[0003] Fingerprint recognition technology employs various imaging techniques, including optical, capacitive, and ultrasonic imaging modules. One such technique involves using an optical imaging module to capture the fingerprint image. The working principle of an optical fingerprint imaging module is as follows: When a finger is pressed against the protective cover of the module, light emitted from a light source forms incident light. This incident light passes through the image sensor and the protective cover before being projected onto the interface between the cover and the finger. Reflection and refraction occur at the point of contact between the finger and the cover. The image sensor collects this reflected light, converts the optical signal into an electrical signal, and processes it to obtain the fingerprint image.

[0004] To adjust the optical path and improve image quality, microlenses are incorporated into fingerprint imaging modules. However, the performance of existing fingerprint imaging modules with microlenses requires further improvement. Summary of the Invention

[0005] The problem solved by this invention is to provide a signal readout method and readout device for a fingerprint imaging module, so as to improve the performance of the fingerprint imaging module.

[0006] To address the aforementioned problems, this invention provides a signal readout method for a fingerprint imaging module. The fingerprint imaging module includes: a pixel array comprising multiple pixel groups, each pixel group comprising n pixel units, where n is an integer greater than 1; a microlens array located on the pixel array, the microlens array comprising multiple microlenses; each microlens corresponding one-to-one with a pixel group; signal light carrying fingerprint information is transmitted through the microlens array and projected onto the pixel array; each pixel unit in a pixel group performs photoelectric conversion on the signal light transmitted through its corresponding microlens to obtain a unit signal; the signal readout method includes: obtaining a group signal of the pixel group based on the unit signals of m pixel units in the pixel group, where m is greater than or equal to 1 and less than n; and obtaining a fingerprint image based on the group signals of multiple pixel groups.

[0007] Optionally, in a plane parallel to the surface of the pixel array, the size of the pixel unit is in the range of 2μm to 80μm, and the size of the microlens is in the range of 4μm to 500μm.

[0008] Optionally, the size of the microlens is in the range of 4μm to 500μm in a plane perpendicular to the surface of the pixel array.

[0009] Optionally, the step of obtaining the group signal of the pixel group includes: using the unit signal of a pixel unit in the pixel group as the group signal of the pixel group.

[0010] Optionally, the intersection of the optical axis of the signal light and the surface of the pixel group is the first projection point; the unit signal of the pixel unit where the first projection point is located is used as the group signal of the pixel group.

[0011] Optionally, the focal point between the optical axis of the ambient light and the surface of the pixel group is the second projection point; the unit signal outside the pixel unit where the second projection point is located is used as the group signal of the pixel group.

[0012] Optionally, the microlens is a convex lens; the projection of the microlens onto the plane of the pixel group surface is circular; the unit signal of the pixel unit where the center of the circle projected by the microlens onto the pixel group surface is located is used as the group signal of the pixel group; or, the unit signal of the pixel unit other than the pixel unit where the center of the circle projected by the microlens onto the pixel group surface is located is used as the group signal of the pixel group.

[0013] Optionally, the step of obtaining the group signal of the pixel group includes: obtaining the group signal of the pixel group based on the unit signals of multiple pixel units in the pixel group.

[0014] Optionally, the step of obtaining the group signal of the pixel group includes: using the average value of the unit signals of multiple pixel units in the pixel group as the group signal of the pixel group; or, using the sum of the unit signals of multiple pixel units in the pixel group as the group signal of the pixel group.

[0015] Optionally, the imaging module further includes: an aperture array, the aperture array being located between the pixel array and the microlens array, the aperture array including multiple aperture holes; the pixel unit performing photoelectric conversion on the signal light transmitted through the aperture holes.

[0016] Optionally, the aperture corresponds one-to-one with the pixel unit; or, the aperture corresponds to a portion of the pixel units.

[0017] Optionally, the step of obtaining the group signal of the pixel group includes: obtaining a first group signal of the pixel group based on the unit signals of m first pixel units in the pixel group; obtaining a second group signal of the pixel group based on the unit signals of m second pixel units in the pixel group; wherein the first pixel units and the second pixel units are arranged in a point-symmetric manner on the pixel array surface; the step of obtaining a fingerprint image includes: obtaining a first fingerprint image based on the first group signal; obtaining a second fingerprint image based on the second group signal; the signal readout method further includes: performing fake fingerprint judgment based on the first fingerprint image and the second fingerprint image.

[0018] Optionally, the step of determining a fake fingerprint includes: determining that the fingerprint is a genuine fingerprint when there is a difference between the first fingerprint image and the second fingerprint image.

[0019] Optionally, the step of obtaining the group signal of the pixel group includes: obtaining the group signal of the pixel group based on the unit signals of m randomly selected pixel units in the pixel group.

[0020] Accordingly, the present invention also provides a signal readout device for a fingerprint imaging module, the fingerprint imaging module comprising: a pixel array, the pixel array comprising multiple pixel groups, each pixel group comprising n pixel units; a microlens array, the microlens array being located on the pixel array, the microlens array comprising multiple microlenses; each microlens corresponding one-to-one with a pixel group; signal light carrying fingerprint information is transmitted through the microlens array and projected onto the pixel array; each pixel unit performs photoelectric conversion on the signal light transmitted through the multiple microlenses to obtain a unit signal; the signal readout device comprising: a group signal module, the group signal module obtaining a group signal of the pixel group based on the unit signals of m pixel units in the pixel group, wherein m is greater than or equal to 1 and less than n; and an image module, the image module obtaining a fingerprint image based on the group signals of the multiple pixel groups.

[0021] Optionally, in a plane parallel to the surface of the pixel array, the size of the pixel unit is in the range of 2μm to 80μm, and the size of the microlens is in the range of 4μm to 500μm.

[0022] Optionally, the size of the microlens is in the range of 4μm to 500μm in a plane perpendicular to the surface of the pixel array.

[0023] Optionally, the group signal module uses the unit signal of a pixel unit in the pixel group as the group signal of the pixel group.

[0024] Optionally, the intersection of the optical axis of the signal light and the surface of the pixel group is the first projection point;

[0025] The group signal module uses the unit signal of the pixel unit where the first projection point is located as the group signal of the pixel group.

[0026] Optionally, the focal point between the optical axis of the ambient light and the surface of the pixel group is the second projection point; the group signal module uses the unit signal other than the pixel unit where the second projection point is located as the group signal of the pixel group.

[0027] Optionally, the microlens is a convex lens; the projection of the microlens onto the plane of the pixel group surface is circular; the group signal module uses the unit signal of the pixel unit where the center of the circle projected by the microlens onto the pixel group surface is located as the group signal of the pixel group; or, the group signal module uses the unit signal of the pixel unit other than the pixel unit where the center of the circle projected by the microlens onto the pixel group surface is located as the group signal of the pixel group.

[0028] Optionally, the group signal module obtains the group signal of the pixel group based on the unit signals of multiple pixel units in the pixel group.

[0029] Optionally, the group signal module uses the average value of the unit signals of multiple pixel units in the pixel group as the group signal of the pixel group; or, the group signal module uses the sum of the unit signals of multiple pixel units in the pixel group as the group signal of the pixel group.

[0030] Optionally, the group signal module obtains a first group signal of the pixel group based on the unit signals of m first pixel units in the pixel group; and obtains a second group signal of the pixel group based on the unit signals of m second pixel units in the pixel group; the first pixel units and the second pixel units are arranged in a point-symmetric manner on the pixel array surface; the image module obtains a first fingerprint image based on the first group signal; and obtains a second fingerprint image based on the second group signal; the signal reading device further includes a fake fingerprint judgment module, which performs fake fingerprint judgment based on the first fingerprint image and the second fingerprint image.

[0031] Optionally, the fake fingerprint identification module determines that the fingerprint is a genuine fingerprint when there is a difference between the first fingerprint image and the second fingerprint image.

[0032] Optionally, the group signal module obtains the group signal of the pixel group based on the unit signals of m randomly selected pixel units in the pixel group.

[0033] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0034] The signal readout method and device for the fingerprint imaging module provided by this invention include a pixel group corresponding to a microlens, comprising multiple pixel units. That is, the pixel units and the microlens are arranged in a many-to-one ratio. Furthermore, during signal readout, the group signal of the pixel group is obtained from the unit signals of m pixel units (less than n) within the pixel group, thereby obtaining the fingerprint image. This invention's technical solution can achieve both improved material area utilization and full utilization of the pixel units by having them closely adjacent, without requiring image stitching.

[0035] In an optional embodiment of the present invention, the size of the pixel unit is in the range of 2μm to 80μm, and the size of the microlens is in the range of 4μm to 500μm. The size of the microlens is adapted to the spacing between the fingerprint ridges, thereby ensuring the quality of the obtained fingerprint image; moreover, in the plane perpendicular to the surface of the pixel array, the size of the microlens is in the range of 4μm to 500μm, that is, the vector height of the microlens (wherein the vector height of the lens refers to the distance between the lowest point of the lens and the highest point of the arc surface) is in the range of 0.1μm to 10μm. On the one hand, this ensures that the focal length of the microlens is appropriate, allowing the focal point of the microlens to be set at the photosensitive position of the pixel unit, and the focal plane of the microlens array to be located on the imaging plane of the pixel array, thereby effectively improving the imaging quality; on the other hand, the appropriate height of the microlens will not excessively affect the thickness of the fingerprint imaging module, and can also effectively control the manufacturing difficulty of the microlens.

[0036] In an optional embodiment of the present invention, the unit signal of one pixel unit in the pixel group is used as the group signal of the pixel group. By selecting the unit signal of one pixel unit in the pixel group as the group signal, and particularly by using the unit signals other than those of the pixel unit where the second projection point is located as the group signal of the pixel group during the selection process, the imaging direction of ambient light can be avoided, thereby helping to suppress noise signals and improve the signal-to-noise ratio.

[0037] In an optional embodiment of the present invention, the first fingerprint image and the second fingerprint image can be obtained using the unit signals of the first pixel unit and the second pixel unit, which are point-symmetric. If it is a genuine finger fingerprint, because the finger has a certain degree of three-dimensional shape, although the first and second pixel units are point-symmetric, the first fingerprint image and the second fingerprint image will have relatively large differences. If the fingerprint is a planar fake fingerprint, the first fingerprint image and the second fingerprint image will be very similar, almost identical. Therefore, based on the first and second pixel units, the discrimination of planar fake fingerprints can be achieved.

[0038] In an optional embodiment of the present invention, a group signal for the pixel group is obtained based on the unit signals of m randomly selected pixel units within the pixel group. The fingerprint image obtained based on the aforementioned group signal can avoid the inherent frequency of the screen during coupling with the screen, effectively reducing the probability of moiré patterns appearing. Attached Figure Description

[0039] Figure 1 This is a top view schematic diagram of a fingerprint imaging module;

[0040] Figure 2 yes Figure 1 A schematic diagram of the cross-sectional structure of a single pixel unit in the fingerprint imaging module shown.

[0041] Figure 3 This is a cross-sectional structural diagram of a single pixel unit in another fingerprint imaging module;

[0042] Figure 4 This is a cross-sectional structural diagram of a single pixel unit in another fingerprint imaging module;

[0043] Figure 5 This is a cross-sectional structural diagram of a pixel unit in another fingerprint imaging module;

[0044] Figure 6 This is a top view of the fingerprint imaging module used in one embodiment of the signal readout method of the fingerprint imaging module of the present invention.

[0045] Figure 7 yes Figure 6 A schematic cross-sectional view of a single pixel group in the illustrated embodiment;

[0046] Figure 8 This is a cross-sectional view of a single pixel group within the fingerprint imaging module used in another embodiment of the signal readout method of the fingerprint imaging module of the present invention.

[0047] Figure 9 This is a top view of a single pixel group within the fingerprint imaging module used in another embodiment of the signal readout method of the fingerprint imaging module of the present invention.

[0048] Figure 10 This is a schematic diagram of another embodiment of the signal reading device of the fingerprint imaging module of the present invention. Detailed Implementation

[0049] As can be seen from the background art, the performance of fingerprint imaging modules with microlenses in the existing technology needs to be improved. The performance of fingerprint imaging modules with microlenses will now be analyzed in conjunction with their structure:

[0050] refer to Figure 1 and Figure 2 ,in Figure 1 This is a top view schematic diagram of a fingerprint imaging module; Figure 2 yes Figure 1 The diagram shows a cross-sectional view of a single pixel unit in the fingerprint imaging module.

[0051] The fingerprint imaging module includes: a pixel unit 11, which is arranged in an array to form a pixel array 01, and the pixel unit 11 is used to collect signal light 10; and a microlens 12, which is located above the pixel unit 11 in a corresponding manner, and the microlens is used to converge the signal light 10.

[0052] To prevent stray light from interfering with the acquisition of signal 10, the angle of signal light 10 needs to be selected (usually vertical incidence). The aperture of aperture 13 is generally small. Therefore, the size D of pixel unit 11 is relatively large relative to the aperture D of aperture 13. However, under this configuration, the area utilization of pixel unit 11 is low, and pixel unit 11 is not fully utilized.

[0053] If the area of ​​the pixel unit 11 and the microlens 12 is reduced at the same time, that is, the diameter of the pixel unit 11 and the microlens 12 are reduced synchronously, the microlens 12 needs to have a certain thickness in order to have a suitable focal length to ensure its function of converging light; however, the limitation of the thickness of the microlens 12 may cause the fingerprint imaging module to face the problem of being too thick.

[0054] If we unilaterally reduce the area of ​​the pixel unit, that is, keep the microlenses constant and only reduce the area of ​​the pixel unit, such as Figure 3 As shown in the middle pixel unit 21, the material used to form the pixel unit will leave a large blank area ml, which is not conducive to the utilization of the material surface area and easily leads to material waste.

[0055] refer to Figure 4 This shows a schematic diagram of the cross-sectional structure of a single pixel unit in another fingerprint imaging module.

[0056] In the fingerprint imaging module, the pixel unit 31 and the microlens 32 are arranged in a one-to-many configuration, meaning that multiple microlenses 32 are disposed on one pixel unit 31. Because multiple microlenses 32 are disposed on a single pixel unit 31, the processing technology of these multiple microlenses 32 requires high precision. Furthermore, crosstalk may exist between different microlenses, and poor processing of one of the multiple microlenses 32 (e.g., Figure 3 The stray light 30a that crosstalks into the microlens 32a can affect the quality of the signal acquired by the entire pixel unit.

[0057] refer to Figure 5 This shows a cross-sectional structural diagram of a pixel unit in another fingerprint imaging module.

[0058] In the fingerprint imaging module, the pixel units 42 and the microlenses 42 are arranged in a many-to-one manner, that is, one microlens 42 corresponds to multiple pixel units 41. Due to manufacturing limitations, there is a gap m2 between adjacent microlenses 42. Therefore, the signals obtained by different microlenses 42 need to be stitched together to obtain a fingerprint image. However, image stitching not only incurs computational costs but may also affect the accuracy of the image.

[0059] Increasing the pixel unit area to form a non-pixel-level fingerprint imaging module can easily lead to more image distortion. Furthermore, when integrated with other devices, it can also easily result in moiré patterns, thus affecting the quality of the obtained fingerprint image.

[0060] To solve the above-mentioned technical problems, the present invention provides a signal readout method for a fingerprint imaging module, comprising:

[0061] The fingerprint imaging module includes: a pixel array comprising multiple pixel groups, each pixel group comprising n pixel units, where n is an integer greater than 1; a microlens array located on the pixel array, the microlens array comprising multiple microlenses; each microlens corresponding one-to-one with a pixel group; signal light carrying fingerprint information is transmitted through the microlens array and projected onto the pixel array; each pixel unit in a pixel group performs photoelectric conversion on the signal light transmitted through its corresponding microlens to obtain a unit signal; the signal readout method includes: obtaining a group signal of the pixel group based on the unit signals of m pixel units in the pixel group, where m is greater than or equal to 1 and less than n; and obtaining a fingerprint image based on the group signals of multiple pixel groups.

[0062] The technical solution of the present invention can improve the material area utilization rate by closely aligning the pixel units, while also making full use of the pixel units, and without the need for image stitching.

[0063] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0064] refer to Figure 6 and Figure 7 This diagram illustrates the structure of a fingerprint imaging module used in an embodiment of the fingerprint imaging module signal readout method of the present invention, wherein... Figure 6 This is a top-down structural diagram. Figure 7 This is a schematic diagram of the cross-sectional structure of a single pixel group.

[0065] The fingerprint imaging module includes: a pixel array 100, which includes multiple pixel groups 110, each pixel group including n pixel units 111, where n is an integer greater than 1; a microlens array 120, which is located on the pixel array 100 and includes multiple microlenses 121; each microlens 121 corresponds one-to-one with a pixel group 110; signal light carrying fingerprint information is transmitted through the microlens array 120 and projected onto the pixel array 100; each pixel unit 111 performs photoelectric conversion on the signal light transmitted through the multiple microlenses 121 to obtain a unit signal.

[0066] The signal readout method includes: obtaining a group signal of pixel group 110 based on the unit signals of m pixel units 111 in pixel group 110, where m is greater than or equal to 1 and less than n; and obtaining a fingerprint image based on the group signals of multiple pixel groups 110.

[0067] In the signal readout method, the pixel units and the microlenses are arranged in a many-to-one manner; and during signal readout, the group signal of the pixel group is obtained based on the unit signals of m pixel units less than n in the pixel group, thereby obtaining the fingerprint image. This method can improve the material area utilization rate by having the pixel units closely adjacent to each other, while also making full use of the pixel units, and without the need for image stitching.

[0068] In this embodiment, the pixel group 110 includes 25 pixel units 111 arranged in an array, wherein the 25 pixel units 111 form a 5×5 array. The figure shows four pixel groups 110 arranged in a 2×2 array.

[0069] The microlens array 120 includes a plurality of microlenses 121 arranged in an array. Figure 6 The image shows four microlenses 121 arranged in a 2×2 array. Each microlens 121 corresponds one-to-one with a pixel group 110. Figure 6 As shown, the microlens 121 is located directly above its corresponding pixel group 110, and the projection of the microlens 121 onto the surface of the pixel array 100 is within the range of the pixel group 110.

[0070] like Figure 7 As shown, the signal light 101 carries fingerprint information and is projected onto the pixel array 100 after passing through the microlens array. The pixel group 110 (e.g., Figure 6 In the diagram, pixel unit 111 performs photoelectric conversion on the signal light 101a, 101b, 101c transmitted through the corresponding microlens 121 to obtain unit signals.

[0071] The signal readout method includes: obtaining a group signal of the pixel group based on the unit signals of some pixel units in the pixel group 110; and obtaining a fingerprint image based on the group signals of multiple pixel groups in the pixel array 100.

[0072] It should be noted that in this embodiment, within the plane parallel to the surface of the pixel array 100, the size of the pixel unit 111 is in the range of 2μm to 80μm, and the size of the microlens 121 is in the range of 4μm to 500μm. Since the spacing of fingerprints is approximately in the range of 100μm to 300μm, the size of the microlens 121 is adapted to the spacing between the fingerprint ridges, thereby ensuring the quality of the fingerprint image without wasting resources due to excessively high precision.

[0073] Furthermore, the size of the microlens 121 is within the range of 20μm to 500μm in the plane perpendicular to the surface of the pixel array 100, meaning the height of the microlens 121 is within the range of 20μm to 500μm. The appropriate planar dimensions (i.e., the dimensions in the plane parallel to the surface of the pixel array 100) and height of the microlens 121 ensure that the focal length of the microlens 121 is suitable, allowing the focal point of the microlens 121 to be set at the photosensitive position of the pixel unit, and ensuring that the focal plane of the microlens array 120 is located on the imaging plane of the pixel array, thereby effectively improving image quality. On the other hand, the appropriate height of the microlens 121 does not excessively affect the thickness of the fingerprint imaging module, and also effectively controls the manufacturing difficulty of the microlens 121.

[0074] In this embodiment, the step of obtaining the group signal of the pixel group 110 includes: using the unit signal of a single pixel unit 111 in the pixel group 110 as the group signal of the pixel group 110. Since the microlenses correspond one-to-one with the pixel groups, the resolution of the pixel group signal is consistent with the resolution of the microlens array. Using the unit signal of a single pixel unit 111 in the pixel group 110 as the group signal can reduce the data processing difficulty and improve the imaging speed while meeting the resolution requirements of fingerprint image quality.

[0075] Specifically, the intersection of the optical axis of the signal light and the surface of the pixel group 110 is the first projection point; the unit signal of the pixel unit where the first projection point is located is used as the group signal of the pixel group. Here, the optical axis of the signal light refers to the center line of the signal light beam.

[0076] like Figure 6As shown, in this embodiment, the microlens 121 is a convex lens; the projection of the microlens 121 onto the plane of the pixel group 110 is circular; the unit signal of the pixel unit 111 where the center of the circle projected by the microlens 121 onto the surface of the pixel group is located is used as the group signal of the pixel group 110.

[0077] Specifically, the signal light is incident on the surface of the pixel array at a perpendicular angle; therefore, for a single pixel group 110, the first projection point 112 (e.g., Figure 6 (As shown) is located at the center of the pixel group 110; as Figure 7 As shown, the first projection point is located at the position of pixel unit 111b. Therefore, in this embodiment, the unit signal of pixel unit 111b is used as the group signal of pixel group 110. In other embodiments of the present invention, the unit signals of other pixel units can also be used as the group signals of the pixel group, that is, the unit signals of pixel unit 111a or pixel unit 111c can also be used as the group signals of pixel group 110.

[0078] The method of obtaining the group signal of the pixel group based on the position of the first projection point is only one example. In other embodiments of the present invention, the focal point between the optical axis of the ambient light and the surface of the pixel group is the second projection point; the unit signal other than the pixel unit where the second projection point is located is used as the group signal of the pixel group. By avoiding the pixel unit where the second projection point is located, the imaging direction of the ambient light can be avoided, which can effectively eliminate the influence of ambient light on the fingerprint image quality, which is beneficial to suppressing noise signals and improving the signal-to-noise ratio.

[0079] like Figure 8 As shown, the ambient light 102 is incident on the surface of the pixel array at a vertical angle; the microlens 122 is a convex lens, and the projection of the microlens in the plane of the pixel group surface is circular. The unit signal of the pixel unit other than the pixel unit where the center of the circle projected by the microlens 122 on the pixel group surface is located is used as the group signal of the pixel group.

[0080] Specifically, the center of the projection of the microlens 122 onto the surface of the pixel group is located within the pixel unit 112b. Therefore, the unit signal of the pixel unit other than the pixel unit 112b is used as the group signal of the pixel group. For example, the unit signal of the pixel unit 112a or the pixel unit 112c is used as the group signal of the pixel group.

[0081] Continue to refer to Figure 6 and Figure 7In this embodiment, the imaging module further includes an aperture array 130, which is located between the pixel array 110 and the microlens array 120. The aperture array 130 includes multiple aperture holes 131. The pixel unit 111 performs photoelectric conversion on the signal light transmitted through the aperture holes 131. The aperture array 130 with aperture holes 131 can effectively suppress crosstalk between different pixel units, which is beneficial to improving the signal-to-noise ratio.

[0082] like Figure 6 and Figure 7 As shown, in this embodiment, the aperture 131 corresponds one-to-one with the pixel unit 111, meaning the aperture is set across the entire angle within the pixel array surface. This method of setting the aperture is merely an example. In other embodiments of the present invention, the aperture can also be set at positions corresponding to some pixel units, meaning the aperture can be set within a portion of the angle within the pixel array surface; for example, the aperture can be set only within 1 / 4 of the angle. Figure 9 As shown, the nine pixel units 311 in the pixel group 310 of the pixel array 300 are arranged in a 3×3 pattern, and only the positions of the 2×2 pixel units 311 are provided with aperture holes 331.

[0083] It should be noted that using the unit signal of a single pixel unit 111 in the pixel group 110 as the group signal of the pixel group 110 is only an example. In other embodiments of the present invention, the group signal can also be obtained from the unit signals of more than one pixel unit in the pixel group.

[0084] Specifically, refer to the following: Figure 10 The diagram shows a top view of the fingerprint imaging module used in another embodiment of the signal readout method of the fingerprint imaging module of the present invention.

[0085] The similarities between this embodiment and the previous embodiments are not repeated here. The difference between this embodiment and the previous embodiments lies in that, in this embodiment, the step of obtaining the group signal of the pixel group 410 includes: obtaining the group signal of the pixel group 410 based on the unit signals of a plurality of pixel units 411 in the pixel group 410. Wherein, the average value of the unit signals of the plurality of pixel units 411 in the pixel group 410 is used as the group signal of the pixel group 410. In other embodiments of the present invention, in the step of obtaining the group signal, the sum of the unit signals of the plurality of pixel units in the pixel group is used as the group signal of the pixel group.

[0086] Furthermore, in this embodiment, the fingerprint imaging module is disposed below the display screen, and the fingerprint imaging module uses the display screen as a light source, that is, part of the light generated by the display screen forms the signal light on the sensing surface. The step of obtaining the group signal of the pixel group 410 includes: obtaining the group signal of the pixel group 410 based on the unit signals of m randomly selected pixel units 411 in the pixel group 410. Since the selection of pixel units 411 is random, the selection of pixel units can avoid the inherent frequency of the display screen, so the probability of moiré patterns can be effectively reduced in coupling with the display screen; moreover, this approach does not require too many modifications to the structure of the fingerprint imaging module and the display screen, which can effectively reduce the manufacturing difficulty.

[0087] Therefore, in this embodiment, the step of obtaining the group signal of the pixel group 410 includes: randomly selecting 3 pixel units 411 from the 25 pixel units 411 in the pixel group 410; taking the average value of the unit signals of the selected 3 pixel units 411, and using the obtained average value as the group signal of the pixel group 410, thereby obtaining a fingerprint image.

[0088] It should also be noted that in some other embodiments of the present invention, the step of obtaining the group signal of the pixel group includes: obtaining a first group signal of the pixel group based on the unit signals of m first pixel units in the pixel group; obtaining a second group signal of the pixel group based on the unit signals of m second pixel units in the pixel group; the first pixel units and the second pixel units are arranged in a point-symmetric manner on the pixel array surface; the step of obtaining a fingerprint image includes: obtaining a first fingerprint image based on the first group signal; obtaining a second fingerprint image based on the second group signal; the signal readout method further includes: performing a fake fingerprint judgment based on the first fingerprint image and the second fingerprint image. Specifically, the step of performing a fake fingerprint judgment includes: judging the fingerprint as a genuine fingerprint when there is a difference between the first fingerprint image and the second fingerprint image.

[0089] If it is a real fingerprint, because the finger has a certain degree of three-dimensional shape, although the first and second pixel units are set symmetrically, the first fingerprint image and the second fingerprint image will have relatively large differences. If the fingerprint is a planar fake fingerprint, then the first fingerprint image and the second fingerprint image are very similar, almost identical. Therefore, based on the first and second pixel units, the discrimination of planar fake fingerprints can be realized. That is, when the first fingerprint image and the second fingerprint image are different, the fingerprint is judged to be a real fingerprint; when the first fingerprint image and the second fingerprint image are not different, the fingerprint is judged to be a fake fingerprint.

[0090] Accordingly, the present invention also provides a signal readout device for a fingerprint imaging module, in conjunction with a reference. Figure 6 and Figure 7 ,in Figure 6 A top view of the fingerprint imaging module is shown. Figure 7 It shows Figure 6 A schematic diagram of the cross-sectional structure of a single pixel group.

[0091] The fingerprint imaging module includes: a pixel array 100, which includes multiple pixel groups 110, each pixel group 110 including n pixel units 111; a microlens array 120, which is located on the pixel array 100 and includes multiple microlenses 121; each microlens 121 corresponds to a pixel group 110; signal light carrying fingerprint information is transmitted through the microlens array 120 and projected onto the pixel array 100; each pixel unit 111 performs photoelectric conversion on the signal light transmitted through the multiple microlenses 121 to obtain a unit signal.

[0092] The signal reading device 160 includes: a group signal module 140, which obtains a group signal of the pixel group 110 based on the unit signals of m pixel units 111 in the pixel group 110, where m is greater than or equal to 1 and less than n; and an image module 150, which obtains a fingerprint image based on the group signals of multiple pixel groups 110.

[0093] The pixel unit 111 and the microlens 121 are arranged in a many-to-one manner; the signal reading device 160 obtains the group signal of the pixel group 110 based on the unit signals of m pixel units 111 (less than n) in the pixel group 110, and then obtains the fingerprint image. This can improve the material area utilization rate by having the pixel units 111 closely adjacent to each other, while also making full use of the pixel units 111, and without the need for image stitching.

[0094] In this embodiment, the pixel group 110 includes 25 pixel units 111 arranged in an array, wherein the 25 pixel units 111 form a 5×5 array. The figure shows four pixel groups 110 arranged in a 2×2 array.

[0095] The microlens array 120 includes a plurality of microlenses 121 arranged in an array. Figure 6 The image shows four microlenses 121 arranged in a 2×2 array. Each microlens 121 corresponds one-to-one with a pixel group 110. Figure 6 As shown, the microlens 121 is located directly above its corresponding pixel group 110, and the projection of the microlens 121 onto the surface of the pixel array 100 is within the range of the pixel group 110.

[0096] like Figure 7 As shown, the signal light 101 carries fingerprint information and is projected onto the pixel array 100 after passing through the microlens array. The pixel group 110 (e.g., Figure 6 In the diagram, pixel unit 111 performs photoelectric conversion on the signal light 101a, 101b, 101c transmitted through the corresponding microlens 121 to obtain unit signals.

[0097] In this embodiment, the signal reading device 160 obtains the group signal of the pixel group 110 based on the unit signal of some pixel units in the pixel group 110; and the group signals of multiple pixel groups in the pixel array 100 obtain a fingerprint image.

[0098] It should be noted that in this embodiment, within the plane parallel to the surface of the pixel array 100, the size of the pixel unit 111 is in the range of 2μm to 80μm, and the size of the microlens 121 is in the range of 4μm to 500μm. Since the spacing of fingerprints is approximately in the range of 100μm to 300μm, the size of the microlens 121 is adapted to the spacing between the fingerprint ridges, thereby ensuring the quality of the fingerprint image without wasting resources due to excessively high precision.

[0099] Furthermore, the size of the microlens 121 is within the range of 20μm to 500μm in the plane perpendicular to the surface of the pixel array 100, meaning the height of the microlens 121 is within the range of 20μm to 500μm. The appropriate planar dimensions (i.e., the dimensions in the plane parallel to the surface of the pixel array 100) and height of the microlens 121 ensure that the focal length of the microlens 121 is suitable, allowing the focal point of the microlens 121 to be set at the photosensitive position of the pixel unit, and ensuring that the focal plane of the microlens array 120 is located on the imaging plane of the pixel array, thereby effectively improving image quality. On the other hand, the appropriate height of the microlens 121 does not excessively affect the thickness of the fingerprint imaging module, and also effectively controls the manufacturing difficulty of the microlens 121.

[0100] In this embodiment, the group signal module 140 uses the unit signal of a single pixel unit 111 in the pixel group 110 as the group signal of the pixel group 110. Since the microlenses correspond one-to-one with the pixel groups, the resolution of the pixel group signal is consistent with the resolution of the microlens array. Using the unit signal of a single pixel unit 111 in the pixel group 110 as the group signal can reduce the data processing difficulty and improve the imaging speed while meeting the resolution requirements of fingerprint image quality.

[0101] Specifically, the intersection of the optical axis of the signal light and the surface of the pixel group 110 is the first projection point; the group signal module 140 uses the unit signal of the pixel unit 111 where the first projection point is located as the group signal of the pixel group 110. Here, the optical axis of the signal light refers to the center line of the signal light beam.

[0102] like Figure 6 As shown, in this embodiment, the microlens 121 is a convex lens; the projection of the microlens 121 onto the plane of the pixel group 110 is circular; the group signal module 140 uses the unit signal of the pixel unit 111 where the center of the circle projected by the microlens 121 onto the surface of the pixel group 110 is located as the group signal of the pixel group 110.

[0103] Specifically, the signal light is incident on the surface of the pixel array 100 at a perpendicular angle; therefore, for a single pixel group 110, the first projection point 112 (e.g., Figure 6 (As shown) is located at the center of the pixel group 110; as Figure 7 As shown, the first projection point is located at the position of the pixel unit 111b. Therefore, in this embodiment, the group signal module 140 uses the unit signal of the pixel unit 111b as the group signal of the pixel group 110.

[0104] The method by which the group signal module 140 obtains the group signal based on the position of the first projection point is only one example. In other embodiments of the present invention, the focal point between the optical axis of the ambient light and the surface of the pixel group is the second projection point; the group signal module uses the unit signal of the pixel unit other than the pixel unit where the second projection point is located as the group signal of the pixel group. The method by which the group signal module avoids the pixel unit where the second projection point is located can avoid the imaging direction of the ambient light, effectively eliminate the influence of ambient light on the fingerprint image quality, help suppress noise signals, and improve the signal-to-noise ratio.

[0105] like Figure 8 As shown, the ambient light 102 is incident on the surface of the pixel array at a vertical angle; the microlens 122 is a convex lens, and the projection of the microlens in the plane of the pixel group surface is circular. The group signal module (not shown in the figure) uses the unit signal of the pixel unit other than the pixel unit where the center of the circle projected by the microlens 122 on the pixel group surface is located as the group signal of the pixel group.

[0106] Specifically, the center of the projection of the microlens 122 onto the surface of the pixel group is located within the pixel unit 112b. Therefore, the unit signal of the pixel unit other than the pixel unit 112b is used as the group signal of the pixel group. For example, the unit signal of the pixel unit 112a or the pixel unit 112c is used as the group signal of the pixel group.

[0107] Continue to refer to Figure 6 and Figure 7 In this embodiment, the imaging module further includes an aperture array 130, which is located between the pixel array 110 and the microlens array 120. The aperture array 130 includes multiple aperture holes 131. The pixel unit 111 performs photoelectric conversion on the signal light transmitted through the aperture holes 131. The aperture array 130 with aperture holes 131 can effectively suppress crosstalk between different pixel units, which is beneficial to improving the signal-to-noise ratio.

[0108] like Figure 6 and Figure 7 As shown, in this embodiment, the aperture 131 corresponds one-to-one with the pixel unit 111, meaning the aperture is set across the entire angle within the pixel array surface. This method of setting the aperture is merely an example. In other embodiments of the present invention, the aperture can also be set at positions corresponding to some pixel units, meaning the aperture can be set within a portion of the angle within the pixel array surface; for example, the aperture can be set only within 1 / 4 of the angle. Figure 9 As shown, the nine pixel units 311 in the pixel group 310 of the pixel array 300 are arranged in a 3×3 pattern, and only the positions of the 2×2 pixel units 311 are provided with aperture holes 331.

[0109] It should be noted that the method by which the group signal module obtains the group signal based on the unit signal of a single pixel unit 111 is only one example. In other embodiments of the present invention, the group signal module may also obtain the group signal based on the unit signals of multiple pixel units.

[0110] Specifically, refer to the following: Figure 10 The diagram shows a structural schematic of another embodiment of the signal readout device of the fingerprint imaging module of the present invention.

[0111] The similarities between this embodiment and the previous embodiments are not repeated here. The difference lies in that, in this embodiment, the group signal module 440 obtains the group signal of the pixel group 410 based on the unit signals of the plurality of pixel units 411 in the pixel group 410. Specifically, the group signal module 440 uses the average value of the unit signals of the plurality of pixel units 411 in the pixel group 410 as the group signal of the pixel group 410. In other embodiments of the present invention, the group signal module uses the sum of the unit signals of the plurality of pixel units in the pixel group as the group signal of the pixel group.

[0112] Furthermore, in this embodiment, the fingerprint imaging module is disposed below the display screen, and the fingerprint imaging module uses the display screen as a light source, that is, part of the light generated by the display screen forms the signal light on the sensing surface. The group signal module 440 obtains the group signal of the pixel group 410 based on the unit signals of m randomly selected pixel units 411 in the pixel group 410. Since the selection of pixel units 411 is random, the selection of pixel units can avoid the inherent frequency of the display screen, so in the coupling with the display screen, the probability of moiré patterns appearing in the fingerprint image obtained by the image module 450 can be effectively reduced; moreover, this approach does not require too many modifications to the structure of the fingerprint imaging module and the display screen, which can effectively reduce the manufacturing difficulty.

[0113] Therefore, in this embodiment, the group signal module 440 randomly selects 3 pixel units 411 from the 25 pixel units 411 in the pixel group 410; the group signal module 440 takes the average value of the unit signals of the selected 3 pixel units 411, and uses the obtained average value as the group signal of the pixel group 410; the image module 450 is connected to the group signal module 440 to obtain the group signals of all pixel groups 410, and obtains a fingerprint image based on all group signals.

[0114] It should also be noted that in some other embodiments of the present invention, the group signal module obtains a first group signal of the pixel group based on the unit signals of m first pixel units in the pixel group; and obtains a second group signal of the pixel group based on the unit signals of m second pixel units in the pixel group; the first pixel units and the second pixel units are arranged in a point-symmetric manner on the pixel array surface; the image module obtains a first fingerprint image based on the first group signal; and obtains a second fingerprint image based on the second group signal; the signal reading device further includes a fake fingerprint judgment module, which performs fake fingerprint judgment based on the first fingerprint image and the second fingerprint image. Specifically, the fake fingerprint judgment module judges the fingerprint to be a genuine fingerprint when there is a difference between the first fingerprint image and the second fingerprint image.

[0115] If it is a real fingerprint, because the finger has a certain degree of three-dimensional shape, although the first and second pixel units are set symmetrically, the first fingerprint image and the second fingerprint image will have relatively large differences. If the fingerprint is a planar fake fingerprint, then the first fingerprint image and the second fingerprint image are very similar, almost identical. Therefore, the fake fingerprint detection module can realize the detection of planar fake fingerprints based on the first and second pixel units. That is, when the first fingerprint image and the second fingerprint image are different, the fake fingerprint detection module determines that the fingerprint is a real fingerprint; when the first fingerprint image and the second fingerprint image are not different, the fake fingerprint detection module determines that the fingerprint is a fake fingerprint.

[0116] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A signal readout method for a fingerprint imaging module, characterized in that, The fingerprint imaging module includes: a pixel array, which includes multiple pixel groups, each pixel group including n pixel units, where n is an integer greater than 1; and a microlens array, which is located on the pixel array and includes multiple microlenses; each microlens corresponds one-to-one with a pixel group. Signal light carrying fingerprint information is transmitted through the microlens array and projected onto the pixel array; The pixel units in the pixel group perform photoelectric conversion on the signal light transmitted through the corresponding microlens to obtain unit signals; The signal readout method includes: The group signal of the pixel group is obtained based on the unit signals of m randomly selected pixel units in the pixel group, where m is greater than or equal to 1 and less than n; A fingerprint image is obtained based on the group signals of multiple pixel groups.

2. The signal readout method as described in claim 1, characterized in that, In a plane parallel to the surface of the pixel array, the size of the pixel unit is in the range of 2μm to 80μm, and the size of the microlens is in the range of 4μm to 500μm.

3. The signal readout method as described in claim 2, characterized in that, In a plane perpendicular to the surface of the pixel array, the size of the microlens is in the range of 4μm to 500μm.

4. The signal readout method as described in claim 1, characterized in that, The step of obtaining the group signal of the pixel group includes: using the unit signal of a pixel unit in the pixel group as the group signal of the pixel group.

5. The signal readout method as described in claim 4, characterized in that, The intersection of the optical axis of the signal light and the surface of the pixel group is the first projection point; The unit signal of the pixel unit where the first projection point is located is used as the group signal of the pixel group.

6. The signal readout method as described in claim 4, characterized in that, The focal point between the optical axis of the ambient light and the surface of the pixel group is the second projection point; The unit signal outside the pixel unit where the second projection point is located is used as the group signal of the pixel group.

7. The signal readout method according to any one of claims 4 to 6, characterized in that, The microlens is a convex lens; the projection of the microlens onto the plane of the pixel group surface is circular; The unit signal of the pixel unit where the center of the circle projected by the microlens on the surface of the pixel group is located is taken as the group signal of the pixel group; Alternatively, the unit signal of the pixel unit other than the pixel unit where the center of the circle projected by the microlens on the surface of the pixel group is located can be used as the group signal of the pixel group.

8. The signal readout method as described in claim 1, characterized in that, The step of obtaining the group signal of the pixel group includes: obtaining the group signal of the pixel group based on the unit signals of multiple pixel units in the pixel group.

9. The signal readout method as described in claim 8, characterized in that, The step of obtaining the group signal of the pixel group includes: taking the average value of the unit signals of multiple pixel units in the pixel group as the group signal of the pixel group; Alternatively, the sum of the unit signals of multiple pixel units in the pixel group can be used as the group signal of the pixel group.

10. The signal readout method as described in claim 1, characterized in that, The imaging module further includes: an aperture array, which is located between the pixel array and the microlens array, and the aperture array includes multiple aperture holes; The pixel unit performs photoelectric conversion on the signal light transmitted through the aperture.

11. The signal readout method as described in claim 10, characterized in that, Each aperture corresponds to a pixel unit; Alternatively, the aperture may correspond to a portion of the pixel unit.

12. The signal readout method as described in claim 1, characterized in that, The step of obtaining the group signal of the pixel group includes: obtaining a first group signal of the pixel group based on the unit signals of m first pixel units in the pixel group; obtaining a second group signal of the pixel group based on the unit signals of m second pixel units in the pixel group; wherein the first pixel units and the second pixel units are arranged in a point-symmetric manner on the pixel array surface; The steps for obtaining a fingerprint image include: obtaining a first fingerprint image based on the first set of signals; and obtaining a second fingerprint image based on the second set of signals. The signal readout method further includes: determining fake fingerprints based on the first fingerprint image and the second fingerprint image.

13. The signal readout method as described in claim 12, characterized in that, The steps for determining a fake fingerprint include: when there is a difference between the first fingerprint image and the second fingerprint image, the fingerprint is determined to be a genuine fingerprint.

14. A signal readout device for a fingerprint imaging module, characterized in that, The fingerprint imaging module includes: a pixel array, which includes multiple pixel groups, each pixel group including n pixel units; and a microlens array, which is located on the pixel array and includes multiple microlenses; each microlens corresponds one-to-one with a pixel group. Signal light carrying fingerprint information is transmitted through the microlens array and projected onto the pixel array; The pixel unit performs photoelectric conversion on the signal light transmitted through the multiple microlenses to obtain a unit signal; The signal readout device includes: A group signal module obtains a group signal for a pixel group based on the unit signals of m randomly selected pixel units in the pixel group, where m is greater than or equal to 1 and less than n. The image module obtains a fingerprint image based on group signals of multiple pixel groups.

15. The signal readout device as described in claim 14, characterized in that, In a plane parallel to the surface of the pixel array, the size of the pixel unit is in the range of 2μm to 80μm, and the size of the microlens is in the range of 4μm to 500μm.

16. The signal readout device as described in claim 14, characterized in that, In a plane perpendicular to the surface of the pixel array, the size of the microlens is in the range of 4μm to 500μm.

17. The signal readout device as described in claim 14, characterized in that, The group signal module uses the unit signal of one pixel unit in the pixel group as the group signal of the pixel group.

18. The signal readout device as claimed in claim 17, characterized in that, The intersection of the optical axis of the signal light and the surface of the pixel group is the first projection point; The group signal module uses the unit signal of the pixel unit where the first projection point is located as the group signal of the pixel group.

19. The signal readout device as claimed in claim 17, characterized in that, The focal point between the optical axis of the ambient light and the surface of the pixel group is the second projection point; The group signal module uses the unit signal other than the pixel unit where the second projection point is located as the group signal of the pixel group.

20. The signal readout apparatus according to any one of claims 17 to 19, characterized in that, The microlens is a convex lens; the projection of the microlens onto the plane of the pixel group surface is circular; The group signal module uses the unit signal of the pixel unit where the center of the circle projected by the microlens on the surface of the pixel group is located as the group signal of the pixel group. Alternatively, the group signal module may use the unit signal of the pixel unit other than the pixel unit where the center of the circle projected by the microlens on the surface of the pixel group is located as the group signal of the pixel group.

21. The signal readout device as described in claim 14, characterized in that, The group signal module obtains the group signal of the pixel group based on the unit signals of multiple pixel units in the pixel group.

22. The signal readout device as described in claim 21, characterized in that, The group signal module uses the average value of the unit signals of multiple pixel units in the pixel group as the group signal of the pixel group; Alternatively, the group signal module may use the sum of the unit signals of multiple pixel units in the pixel group as the group signal of the pixel group.

23. The signal readout device as described in claim 14, characterized in that, The group signal module obtains a first group signal of the pixel group based on the unit signals of m first pixel units in the pixel group; and obtains a second group signal of the pixel group based on the unit signals of m second pixel units in the pixel group; the first pixel units and the second pixel units are arranged in a point-symmetric manner on the pixel array surface; The image module obtains a first fingerprint image based on the first set of signals; Based on the second set of signals, a second fingerprint image is obtained; The signal reading device further includes a fake fingerprint detection module, which performs fake fingerprint detection based on the first fingerprint image and the second fingerprint image.

24. The signal readout device as described in claim 23, characterized in that, The fake fingerprint detection module determines that the fingerprint is genuine when there is a difference between the first fingerprint image and the second fingerprint image.

Images