Three-dimensional imaging device and method, face recognition method and electronic equipment

Abstract

The invention provides a three-dimensional imaging device and method, a face recognition method and electronic equipment, and relates to the technical field of biological recognition, the three-dimensional imaging device comprises a light source, a polarization device and a light sensing unit which are sequentially arranged along a light path, collection light emitted by the light source is reflected by a target object and then enters the light sensing unit, and the collection light enters the light sensing unit before entering the light sensing unit. A plurality of time sequence polarized lights in different polarization directions are formed through time-sharing polarization modulation of the polarization device, the light sensing unit receives the time sequence polarized lights in sequence according to the time sequence and images the time sequence polarized lights respectively, the contour surface of the target object can be reconstructed more accurately, the reconstructed contour surface is closer to the actual contour surface of the target object, and the accuracy of the contour surface reconstruction is improved. And the identification precision can be improved.

Description

Technical Field

[0001] The present application relates to the field of biometric identification technology, and more specifically, to a three-dimensional imaging device and method, a face recognition method, and an electronic device. Background Art

[0002] With the development of portable terminal devices, the application of biometric technology is becoming more and more extensive and in-depth. Taking electronic devices as an example, fingerprint recognition, face recognition, etc. have been increasingly used in the device screen wake-up and identity authentication steps of various programs, improving the security of the device and the flexibility of its use.

[0003] At present, the main solutions for face recognition include binocular vision, time-of-flight, and structured light. Among them, the binocular vision solution has a limited scope of use because the reconstruction accuracy is proportional to the camera baseline length; the cost of the time-of-flight camera is relatively high, and it is limited by the time resolution, so the accuracy of 3D imaging is not high; although the structured light solution has the advantage of high imaging accuracy, its response speed is slow and the frame rate is low, and as the imaging distance increases, the imaging accuracy decreases. Therefore, another polarization 3D imaging technology that can be used for face recognition has also been gradually developed, but the current polarization 3D imaging technology usually has the problem of poor recognition accuracy. Summary of the invention

[0004] The purpose of this application is to provide a three-dimensional imaging device and method, a face recognition method, and an electronic device to address the deficiencies in the above-mentioned prior art.

[0005] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0006] According to one aspect of an embodiment of the present application, a three-dimensional imaging device is provided, comprising a light source, a polarization device and an image sensor arranged in sequence along an optical path, the image sensor comprising a photosensitive unit, the collection light emitted by the light source is reflected by a target object and then enters the photosensitive unit, and before entering the photosensitive unit, the collection light is time-divided and polarized by the polarization device to form a plurality of sequential polarized lights with different polarization directions, and the plurality of sequential polarized lights each carry polarization information corresponding to a contour surface of the target object and sequentially enter the photosensitive unit.

[0007] Optionally, the polarization device is located between the light source and the target object, and the collection light emitted by the light source is time-divided and polarized by the polarization device to form a plurality of sequential polarized lights. After the plurality of sequential polarized lights are sequentially reflected by the target object, each carrying the polarization information corresponding to the contour surface of the target object sequentially enters the photosensitive unit.

[0008] Optionally, the light source has multiple light emitting surfaces, and the polarization device includes multiple polarization elements corresponding to the multiple light emitting surfaces one by one, each polarization element is located at the light emitting side of the corresponding light emitting surface, and among the multiple polarization elements, the polarization directions of any two polarization elements are different.

[0009] Optionally, the included angle between the polarization directions of any two polarization elements is greater than 10 degrees.

[0010] Optionally, the polarization device includes a first linear polarizer located at a light-emitting side of the light source and a liquid crystal phase retarder, and the first linear polarizer is located between the light source and the liquid crystal phase retarder.

[0011] Optionally, the polarization device includes a first linear polarizer and a driver that are drive-connected, the first linear polarizer is located at a light-emitting side of the light source, and the driver is used to drive the first linear polarizer to rotate around the optical axis of the light source.

[0012] Optionally, a second linear polarizer is further arranged between the target object and the photosensitive unit.

[0013] Optionally, the second linear polarizer is attached to the photosensitive surface of the image sensor.

[0014] Optionally, the second linear polarizer is integrated into the image sensor.

[0015] Optionally, the polarization direction of the second linear polarizer is the same as the polarization direction of one of the multiple sequential polarized lights.

[0016] Optionally, the polarization device is located between the target object and the photosensitive unit. The collection light emitted by the light source assembly is reflected by the target object and then time-dividedly polarized and modulated by the polarization device to form a plurality of sequential polarized lights. The plurality of sequential polarized lights each carry polarization information corresponding to the contour surface of the target object and sequentially enter the photosensitive unit.

[0017] Optionally, the polarization device includes a first linear polarizer and a liquid crystal phase retarder located on the photosensitive side of the photosensitive unit, and the liquid crystal phase retarder is located between the first linear polarizer and the photosensitive unit.

[0018] Optionally, the polarization device includes a first linear polarizer and a driver that are drive-connected, the first linear polarizer is located at a photosensitive side of the photosensitive unit, and the driver is used to drive the first linear polarizer to rotate around the optical axis of the photosensitive unit.

[0019] Optionally, a second linear polarizer is further arranged between the light source and the target object.

[0020] Optionally, the polarization direction of the second linear polarizer is the same as the polarization direction of one of the multiple sequential polarized lights.

[0021] Optionally, a filter is further provided on the photosensitive side of the photosensitive unit, the wavelength band of the collected light is the target wavelength band, and the filter is used to filter out light outside the target wavelength band.

[0022] Another aspect of the present application provides a three-dimensional imaging method, the method comprising:

[0023] Controlling the photosensitive unit to receive a plurality of time-sequential polarized lights in a preset time sequence and form a plurality of polarized images, wherein the polarization directions of any two time-sequential polarized lights are different;

[0024] Obtaining polarization information corresponding to each pixel in the photosensitive unit according to the multiple polarization images;

[0025] The normal vector information of each micro-element in the target object is obtained according to the polarization information corresponding to each pixel in the photosensitive unit and the preset mapping relationship between each pixel in the photosensitive unit and each micro-element in the target object;

[0026] The three-dimensional contour information of the target object is obtained based on the normal vector information of each micro-element in the target object and the position information of each pixel.

[0027] Another aspect of the present application provides a face recognition method, the method comprising:

[0028] Controlling the photosensitive unit to receive multiple sequential polarized lights in a preset time sequence and form multiple polarized images, wherein the collection light emitted by the light source is incident on the photosensitive unit after being reflected by the target object, and the collection light is polarized and modulated by the polarization device before entering the photosensitive unit to form multiple sequential polarized lights with different polarization directions, and the pixel value of the polarized image contains polarization information corresponding to the contour surface of the target object;

[0029] Face recognition is performed based on multiple polarization images to obtain face recognition results. Face recognition includes: face matching and / or anti-counterfeiting recognition.

[0030] According to another aspect of the embodiments of the present application, an electronic device is provided, including a device body and any one of the above-mentioned three-dimensional imaging devices, wherein the three-dimensional imaging device is located in the device body.

[0031] The beneficial effects of this application include:

[0032] The present application provides a three-dimensional imaging device and method, a face recognition method, and an electronic device, including a light source, a polarization device, and an image sensor arranged in sequence along an optical path. The image sensor includes a photosensitive unit. The collection light emitted by the light source is reflected by a target object and then enters the photosensitive unit. Before entering the photosensitive unit, the collection light is polarized and modulated by the polarization device in a time-sharing manner to form a plurality of sequential polarized lights with different polarization directions. The photosensitive unit receives each sequential polarized light in sequence according to a time sequence and images it respectively. By utilizing the different degrees of change in the polarization state of light at each point in the target object, the contour surface of the target object can be reconstructed more accurately, so that the reconstructed contour surface is closer to the actual contour surface of the target object, which helps to improve the recognition accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 This is one of the structural schematic diagrams of a three-dimensional imaging device provided in an embodiment of the present application;

[0035] Figure 2 One of the structural schematic diagrams of a light source and a polarization device provided in an embodiment of the present application;

[0036] Figure 3 A schematic structural diagram of a second linear polarizer and a photosensitive unit provided in an embodiment of the present application;

[0037] Figure 4 A second structural schematic diagram of a three-dimensional imaging device provided in an embodiment of the present application;

[0038] Figure 5 A third structural schematic diagram of a three-dimensional imaging device provided in an embodiment of the present application;

[0039] Figure 6 The second structural schematic diagram of a light source and a polarization device provided in an embodiment of the present application;

[0040] Figure 7 A fourth structural schematic diagram of a three-dimensional imaging device provided in an embodiment of the present application;

[0041] Figure 8 A fifth structural diagram of a three-dimensional imaging device provided in an embodiment of the present application;

[0042] Fig. 9 A sixth structural diagram of a three-dimensional imaging device provided in an embodiment of the present application;

[0043] Fig.10 A schematic flow chart of a three-dimensional imaging method provided in an embodiment of the present application.

[0044] Icons: 100-human face; 200-light source; 210-light emitting surface; 300-light collecting; 400-polarizing device; 401-polarizing element; 410, 440, 450, 480-first linear polarizing plate; 420, 460-liquid crystal phase retarder; 430, 470-driver; 500-photosensitive unit; 600-second linear polarizing plate. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. It should be noted that, in the absence of conflict, the various features in the embodiments of the present application can be combined with each other, and the combined embodiments are still within the scope of protection of the present application.

[0046] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0047] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0048] In order to optimize the imaging effect and improve the recognition accuracy, the present application proposes a three-dimensional imaging device, which can emit a collection light toward the target object and receive the light reflected by the target object, wherein before the three-dimensional imaging device receives the collection light, the collection light is first time-division polarization modulated to form a plurality of sequential polarized lights with a time sequence, so that the three-dimensional imaging device can sequentially receive the plurality of sequential polarized lights in a time sequence and image them respectively, and by comprehensively analyzing the images formed by each sequential polarized light and the position of each receiving pixel, the contour surface of the target object can be reconstructed more accurately, which helps to improve the recognition accuracy. Of course, for ease of understanding, the embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0049] Please refer to Figure 1, shows a three-dimensional imaging device, including a light source 200, a polarizing device 400 and an image sensor, wherein the image sensor includes a photosensitive unit 500. The light source 200 emits a collection light 300 toward a target object, and the collection light 300 is received by the photosensitive unit 500 after being reflected by the target object, so that the photosensitive unit 500 can image the target object. In this process, a light path is formed by the propagation path of the collection light 300, and correspondingly, the light source 200 and the photosensitive unit 500 are both located in the light path and are arranged in sequence along the light path.

[0050] In order to more accurately reconstruct the contour surface of the target object, the polarizer 400 can be arranged in the optical path between the light source 200 and the photosensitive unit 500, so that before the collected light 300 enters the photosensitive unit 500, the polarization device 400 will polarize and modulate the collected light 300 in a time sequence, so as to form a plurality of time-sequential polarized lights with a time sequence, and the polarization directions of any two time-sequential polarized lights are different. In this way, the different polarization directions of the time-sequential polarized lights can be utilized, so as to facilitate better obtaining polarization information during subsequent analysis.

[0051] Therefore, when the multiple sequential polarized lights modulated by the polarization device 400 are incident on the photosensitive unit 500, they will each carry polarization information corresponding to the contour surface of the target object. The photosensitive unit 500 receives each sequential polarized light in chronological order and images it respectively. By utilizing the different degree of change of the polarization state of the light at each point in the target object, the polarization information can be obtained by comprehensively analyzing the images formed by each sequential polarized light, and the degree of change of the polarization state of the light can be obtained by using the polarization information, and then the normal vector of the position in the target object can be determined. In this way, combined with the position of each receiving pixel in the photosensitive unit 500, the contour surface of the target object can be reconstructed more accurately, so that the reconstructed contour surface is closer to the actual contour surface of the target object.

[0052] In this way, in the face 100 recognition scenario, when the target face 100 needs to be recorded, the aforementioned three-dimensional imaging device can make the recorded information closer to the actual contour surface of the target face 100, so that when the recorded information is used as a reference to determine the information of the face 100 to be recognized collected in the subsequent recognition process, it can be more accurately determined whether the face 100 to be recognized is the target face 100. Of course, when collecting the information of the face 100 to be recognized, the aforementioned three-dimensional imaging device can also make the collected information of the face 100 to be recognized closer to the actual contour surface of the face 100 to be recognized, thereby improving the accuracy of recognition.

[0053] It should be understood that the target in this application can be Figure 1The human face 100 and parts of the human face 100 (such as cheeks, nose, eyes) are of course not limited to these, and may also be other objects with three-dimensional dimensions, such as fingers, palms, etc. For ease of understanding, the following description will be taken as an example.

[0054] The polarizer 400 is set in the light path through the above solution. In actual settings, the polarizer 400 can be selectively set between the light source 200 and the target object, or between the target object and the photosensitive unit 500. The specific selection can be made according to the actual application scenario and requirements. The following will be described according to different positions of the polarizer 400 in the light path.

[0055] Please refer to Figure 1 , showing a three-dimensional imaging device in which a polarizer 400 is located between a light source 200 and a target object. When the contour surface of a human face 100 needs to be reconstructed, a collection light 300 is emitted from the light source 200 toward the human face 100, and the collection light 300 first enters the polarizer 400, and the polarizer 400 performs polarization modulation on the collection light 300 in a time sequence, thereby forming a plurality of time-sequential polarized lights with a time sequence, and any two time-sequential polarized lights still satisfy that the polarization directions are different from each other. In this way, the plurality of time-sequential polarized lights with a time sequence will be incident on the human face 100 in sequence in a time sequence, and after being reflected by the human face 100 in sequence in a time sequence, each time-sequential polarized light will carry the polarization information corresponding to the contour surface of the human face 100, and then continue to be received and imaged by the photosensitive unit 500 in a time sequence, thereby reconstructing the contour surface of the human face 100 more accurately.

[0056] For a three-dimensional imaging device in which the polarization device 400 is located between the light source 200 and the target object, when forming a plurality of time-sequential polarized lights, the following examples may be included but are not limited to:

[0057] In one possible example: see Figure 2 , respectively showing a plurality of light emitting surfaces 210 of the light source 200 and a plurality of polarizing elements 401 included in the polarizing device 400. The number of the light source 200 may be one, and the surface of the light source 200 capable of emitting light may be divided into a plurality of separate light emitting surfaces 210, and adjacent light emitting surfaces 210 may be adjacent (e.g. Figure 2 Of course, the light source 200 may also be a plurality of sub-light sources 200 arranged in a two-dimensional array, each of which has a corresponding light emitting surface 210, thereby forming a plurality of light emitting surfaces 210, wherein the plurality of sub-light sources 200 may be an integrated light source 200 packaged together, or may be a plurality of independently separated light sources, as long as they can provide a plurality of light emitting surfaces 210.

[0058] The polarization device 400 includes a plurality of polarization elements 401, and the plurality of polarization elements 401 correspond to the plurality of light-emitting surfaces 210 one by one, so that the light-emitting side of each light-emitting surface 210 has a polarization element 401, so that the collection light 300 emitted by each light-emitting surface 210 can be smoothly incident on the corresponding polarization element 401. Among them, the polarization element 401 can modulate the incident light into linear polarized light, so the polarization direction is the linear polarization direction. And the polarization directions of any two polarization elements 401 are different (such as Figure 2 The dotted line in the polarizing element 401 indicates the polarization direction of the polarizing element 401, and there is an angle between any two dotted lines or the extensions of the dotted lines), so that it is convenient for the subsequent formation of multiple sequential polarized lights, and the polarization directions of any two sequential polarized lights are different. The multiple polarizing elements 401 can be different polarization regions in the same polarizer, or can be multiple separate polarizers.

[0059] pass Figure 2 When the light source 200 and the polarizer 400 shown form a plurality of time-sequential polarized lights: the time periods of the light emitting surfaces 210 of the light source 200 are controlled to be different, for example, the plurality of light emitting surfaces 210 are controlled to emit the collection light 300 in sequence in time, and at the same time, only one light emitting surface 210 emits the collection light 300. In this way, the collection light 300 emitted by each light emitting surface 210 will be incident on the polarizer 400 at different times, so that the polarizer 400 can polarize and modulate the collection light 300 emitted by each light emitting surface 210 in time sequence, thereby forming a plurality of time-sequential polarized lights with a time sequence. In this way, the plurality of time-sequential polarized lights with a time sequence will be incident on the human face 100 in time sequence, and after being reflected by the human face 100 in time sequence, each time-sequential polarized light will carry the polarization information corresponding to the contour surface of the human face 100, and then continue to be received and imaged by the photosensitive unit 500 in time sequence, thereby reconstructing the contour surface of the human face 100 more accurately.

[0060] For example Figure 2As shown, the light source 200 has four light emitting surfaces 210, namely, light emitting surface A1, light emitting surface A2, light emitting surface A3 and light emitting surface A4, and the four light emitting surfaces 210 emit light in time sequence. Correspondingly, the polarization device 400 has four polarization elements 401, namely, polarization element C1, polarization element C2, polarization element C3 and polarization element C4, wherein the light emitting surface A1 corresponds to the polarization element C1, the light emitting surface A2 corresponds to the polarization element C2, the light emitting surface A3 corresponds to the polarization element C3, and the light emitting surface A4 corresponds to the polarization element C4. In the first time period, only the light emitting surface A1 emits light B1; in the second time period, only the light emitting surface A2 emits light B2; in the third time period, only the light emitting surface A3 emits light B3; in the fourth time period, only the light emitting surface A4 emits light B4. Light rays B1, B2, B3 and B4 arrive at the polarization device 400 in chronological order. Specifically, light ray B1 first enters polarization element C1, and after being polarization-modulated by polarization element C1, it is emitted in the same polarization direction as polarization element C1 to form a first time-sequence polarized light; then, light ray B2 enters polarization element C2, and after being polarization-modulated by polarization element C2, it is emitted in the same polarization direction as polarization element C2 to form a second time-sequence polarized light; then, light ray B3 enters polarization element C3, and after being polarization-modulated by polarization element C3, it is emitted in the same polarization direction as polarization element C3 to form a third time-sequence polarized light; finally, light ray B4 enters polarization element C4, and after being polarization-modulated by polarization element C4, it is emitted in the same polarization direction as polarization element C4 to form a fourth time-sequence polarized light.

[0061] Of course, in other possible examples, the number of light emitting surfaces 210 and polarization elements 401 may be other numbers, and the present application does not impose any specific limitation thereto.

[0062] In some possible implementations, the angle between the polarization directions of any two polarization elements 401 is greater than 10 degrees, so that polarization information can be easily obtained by comprehensively analyzing the images formed by polarized light in each time sequence. Figure 2 As shown, the polarization directions of polarization element C1 and polarization element C2 have an angle θ1, and the polarization directions of polarization element C2 and polarization element C4 have an angle θ2, and both angles θ1 and θ2 are greater than 10 degrees. Figure 2 In the example shown, assuming that the polarization direction of polarizing element C1 is 0 degrees, the polarization direction of polarizing element C2 is 45 degrees, the polarization direction of polarizing element C3 is 90 degrees, and the polarization direction of polarizing element C4 is 135 degrees, therefore, angle θ1 is 45 degrees, and angle θ2 is 90 degrees. Of course, this is not limited to this.

[0063] In some possible implementations, the polarization device 400 including a plurality of polarization elements 401 may be integrated and packaged with the light source 200, so that the two may form a whole. Of course, the polarization device 400 may also be disposed separately from the light source 200.

[0064] In another possible example: see Figure 4 , the first linear polarizer 410 and the liquid crystal phase retarder 420 included in the polarization device 400 are respectively shown in the optical path. Among them, the first linear polarizer 410 and the liquid crystal phase retarder 420 are located on the light-emitting side of the light source 200, and the first linear polarizer 410 is located between the light source 200 and the liquid crystal phase retarder 420. The first linear polarizer 410 can modulate the incident light into linear polarized light, so that it is convenient to collect the light 300 that is first modulated by the first linear polarizer 410 and then incident on the liquid crystal phase retarder 420 in the form of linear polarized light. The liquid crystal phase retarder 420 can change the polarization direction of the incident linear polarized light. When it is necessary to form multiple sequential polarized lights in a time sequence, the voltages on both sides of the liquid crystal can be changed successively in a time sequence, so that the deflection angle of the liquid crystal changes successively in a time sequence, thereby multiple sequential polarized lights will be emitted from the liquid crystal phase retarder 420 in a time sequence, and the polarization directions of any two sequential polarized lights are different. In this way, multiple time-sequential polarized lights with a time sequence will be incident on the human face 100 in sequence in time sequence, and after being reflected by the human face 100 in sequence in time sequence, each time-sequential polarized light will carry polarization information corresponding to the contour surface of the human face 100, and then continue to be received and imaged by the photosensitive unit 500 in time sequence, thereby more accurately reconstructing the contour surface of the human face 100.

[0065] In some possible implementations, any one or all of the first linear polarizer 410 and the liquid crystal retarder 420 may be integrated and packaged with the light source 200 to form a whole. Alternatively, any one or all of the first linear polarizer 410 and the liquid crystal retarder 420 may be separated from the light source 200 and provided separately.

[0066] In another possible example: please refer to Figure 5 , the first linear polarizer 440 included in the polarization device 400 and the driver 430 located outside the optical path are shown in the optical path. The first linear polarizer 440 is located on the light-emitting side of the light source 200, and the first linear polarizer 440 and the driver 430 are connected in a driving manner. The present application does not limit the transmission form between the two, for example, they can be connected in the form of gears, worm gears, etc. Please refer to Figure 6 The driver 430 can drive the first linear polarizer 440 to rotate clockwise or counterclockwise around the optical axis a of the light source 200 .

[0067] When it is necessary to form multiple sequential polarized lights in a time sequence, the driver 430 can drive the first linear polarizer 440 to rotate around the optical axis a of the light source 200. During the rotation of the first linear polarizer 440, the polarization direction thereof gradually changes with time. Therefore, when the collection light 300 emitted by the light source 200 continuously or intermittently enters the first linear polarizer 440, due to the different rotation angles of the first linear polarizer 440 at different times, the incident collection light 300 will be modulated by the first linear polarizer 440 into multiple sequential polarized lights with a time sequence, and the polarization directions of any two sequential polarized lights are different. In this way, multiple sequential polarized lights with a time sequence will be incident on the human face 100 in sequence in a time sequence, and after being reflected by the human face 100 in sequence in a time sequence, each sequential polarized light will carry polarization information corresponding to the contour surface of the human face 100, and then continue to be received and imaged by the photosensitive unit 500 in a time sequence, thereby more accurately reconstructing the contour surface of the human face 100.

[0068] Some possible examples include Figure 1 , Figures 3 to 5 As shown, a second linear polarizer 600 is further provided between the target and the photosensitive unit 500, and the second linear polarizer 600 is located on the photosensitive side of the photosensitive unit 500. In this way, after the multiple sequential polarized lights are reflected by the face 100, they first pass through the second linear polarizer 600 and then enter the photosensitive unit 500. By providing the second linear polarizer 600, the photosensitive unit 500 can determine the polarization information of the sequential polarized lights by sensing the brightness of the images formed by each sequential polarized light.

[0069] Some possible examples include Figure 1 , Figures 3 to 5 As shown, the polarization direction of the second linear polarizer 600 is the same as the polarization direction of one of the multiple sequential polarized lights. This allows more light to smoothly pass through the second linear polarizer 600 and enter the photosensitive unit 500, thereby providing more signal light for the photosensitive unit 500, which helps to improve the accuracy of recognition. Figures 1 to 3 It can be seen that the polarization direction of the second linear polarizer 600 is the same as the polarization direction of the polarization element 401. Figure 4 In the embodiment, the polarization direction of the second linear polarizer 600 is consistent with the polarization direction of the sequential polarized light emitted from the liquid crystal phase retarder at a certain moment. Figure 5 In the embodiment, the polarization direction of the second linear polarizer 600 is consistent with the polarization direction of the light modulated by the first linear polarizer 440 at a certain moment.

[0070] In some possible examples, the photosensitive unit 500 may be formed by a plurality of photosensitive units in a two-dimensional array, and the light-receiving surfaces of the plurality of photosensitive units on the same side are combined to form the light-sensitive surface of the photosensitive unit 500 .

[0071] like Figure 1 , Figures 3 to 5 In the three-dimensional imaging device shown, when a second linear polarizer 600 is further disposed between the target object and the photosensitive unit 500, the second linear polarizer 600 may be disposed in the following manners, but is not limited to:

[0072] Form 1: The second linear polarizing plate 600 can be provided separately from the photosensitive unit 500 .

[0073] Form 2: The photosensitive unit 500 is packaged alone or with other layers (such as pixel circuits, microlens arrays, etc.) to form an image sensor, and the second linear polarizer 600 is attached to the photosensitive surface of the image sensor.

[0074] Form three: After the photosensitive unit 500 is packaged individually or with other levels (such as pixel circuits, microlens arrays, etc.) to form an image sensor, an imaging lens is arranged on the photosensitive side of the image sensor, wherein the second linear polarizer 600 can be located between the image sensor and the imaging lens (specifically: the second linear polarizer 600 can be separately arranged from the image sensor and the imaging lens, respectively, or the second linear polarizer 600 can be attached to the light exit surface 210 of the imaging lens). Of course, the second linear polarizer 600 can also be located on the side of the imaging lens away from the image sensor (specifically: the second linear polarizer 600 can be separately arranged from the imaging lens, or the second linear polarizer 600 can be attached to the light incident surface of the imaging lens).

[0075] Form 4: The second linear polarizer 600 is integrated into the image sensor. Specifically, the second linear polarizer 600 is integrated and packaged together with the photosensitive unit 500 to form an image sensor. For example, the packaging level may be at least the photosensitive unit 500, the pixel circuit (pixel light shielding layer), and the second linear polarizer 600 stacked in sequence. For another example, the packaging level may be at least the pixel circuit, the photosensitive unit 500, and the second linear polarizer 600. In addition, the image sensor may also have a microlens array stacked above the second linear polarizer 600.

[0076] Please refer to Figure 7, showing a three-dimensional imaging device in which a polarizing device 400 is located between a target object and a photosensitive unit 500. When the contour surface of a human face 100 needs to be reconstructed, a light source 200 emits a collection light 300 toward the human face 100, and the collection light 300 first enters the human face 100, and then is reflected by the human face 100 and enters the polarizing device 400, and the polarizing device 400 performs polarization modulation on the collection light 300 in a time sequence, thereby forming a plurality of time-sequential polarized lights with a time sequence, and any two time-sequential polarized lights still satisfy different polarization directions. In this way, each time-sequential polarized light will carry polarization information corresponding to the contour surface of the human face 100, and then be received and imaged by the photosensitive unit 500 in a time sequence, thereby reconstructing the contour surface of the human face 100 more accurately.

[0077] For a three-dimensional imaging device in which the polarization device 400 is located between the target object and the photosensitive unit 500, when forming multiple time-sequential polarized lights, it may include but is not limited to the following examples:

[0078] In one possible example: see Figure 8 , the first linear polarizer 450 and the liquid crystal phase retarder 460 included in the polarization device 400 are respectively shown in the optical path. Among them, the first linear polarizer 450 and the liquid crystal phase retarder 460 are located on the photosensitive side of the photosensitive unit 500, and the liquid crystal phase retarder 460 is located between the first linear polarizer 450 and the photosensitive unit 500. The first linear polarizer 450 can modulate the incident light into linear polarized light, so that it is convenient to collect the light 300 first modulated by the first linear polarizer 450 and then incident on the liquid crystal phase retarder 460 in the form of linear polarized light. The liquid crystal phase retarder 460 can change the polarization direction of the incident linear polarized light. When it is necessary to form multiple sequential polarized lights in a time sequence, the voltages on both sides of the liquid crystal can be changed successively in a time sequence, so that the deflection angle of the liquid crystal changes successively in a time sequence, thereby multiple sequential polarized lights will be emitted from the liquid crystal phase retarder 460 in a time sequence, and the polarization directions of any two sequential polarized lights are different. In this way, each time-sequential polarized light will carry polarization information corresponding to the contour surface of the human face 100, and then be received and imaged by the photosensitive unit 500 in time sequence, thereby reconstructing the contour surface of the human face 100 more accurately.

[0079] In another possible example: please refer to Fig. 9, a first linear polarizer 480 included in the polarization device 400 and a driver 470 located outside the optical path are shown in the optical path. The first linear polarizer 480 is located on the photosensitive side of the photosensitive unit 500, and the first linear polarizer 480 and the driver 470 are drivingly connected. The present application does not limit the transmission form between the two, for example, they can be connected in the form of gears, worm gears, etc. And the driver 470 can drive the first linear polarizer 480 to rotate clockwise or counterclockwise around the optical axis of the light source 200.

[0080] When it is necessary to form multiple sequential polarized lights in a time sequence, the driver 470 can drive the first linear polarizer 480 to rotate around the optical axis of the light source 200. During the rotation of the first linear polarizer 480, the polarization direction thereof gradually changes with time. Therefore, when the collection light 300 reflected by the face 100 is incident on the first linear polarizer 480, since the rotation angle of the first linear polarizer 480 is different at different times, the incident collection light 300 will be modulated by the first linear polarizer 480 into multiple sequential polarized lights with a time sequence, and the polarization directions of any two sequential polarized lights are different. In this way, each sequential polarized light will carry polarization information corresponding to the contour surface of the face 100, and then be received and imaged by the photosensitive unit 500 in a time sequence, so as to more accurately reconstruct the contour surface of the face 100.

[0081] Some possible examples include Figures 7 to 9 As shown, a second linear polarizer 600 is further provided between the target object and the light source 200, and the second linear polarizer 600 is located at the light-emitting side of the light source 200. In this way, the collection light 300 emitted by the light source 200 can first pass through the second linear polarizer 600, and then enter the face 100, and then be reflected by the face 100 and enter the polarization device 400. By providing the second linear polarizer 600, it is convenient to control the collection light 300 incident on the face 100 to maintain a linear polarization state, so as to facilitate the subsequent photosensitive unit 500 to comprehensively analyze the images formed by each time-sequential polarized light to obtain polarization information.

[0082] Some possible examples include Figures 7 to 9 As shown, the polarization direction of the second linear polarizer 600 is the same as the polarization direction of one of the multiple sequential polarized lights. This allows more light to enter the photosensitive unit 500 through the polarization device 400, thereby providing more signal light for the photosensitive unit 500, which helps to improve the accuracy of recognition. Figure 8 In the embodiment, the polarization direction of the second linear polarizer 600 is consistent with the polarization direction of the sequential polarized light emitted from the liquid crystal phase retarder at a certain moment. Fig. 9 In the embodiment, the polarization direction of the second linear polarizer 600 is consistent with the polarization direction of the light modulated by the first linear polarizer 480 at a certain moment.

[0083] Some possible examples include Figures 7 to 9 In the three-dimensional imaging device shown, when a second linear polarizer 600 is further disposed between the target object and the light source 200 , the second linear polarizer 600 can be attached to the light emitting surface 210 of the light source 200 , or can be disposed separately from the light source 200 .

[0084] In some possible examples, the photosensitive unit 500 may be formed by a plurality of photosensitive units in a two-dimensional array, and the light-receiving surfaces of the plurality of photosensitive units on the same side are combined to form the photosensitive surface of the photosensitive unit 500. Figures 7 to 9 In the three-dimensional imaging device shown, the polarization device 400 may be arranged in the form of, but not limited to:

[0085] Form 1: Figure 8 As shown, when the polarization device 400 includes the first linear polarizing plate 450 and the liquid crystal retarder 460 , the first linear polarizing plate 450 and the liquid crystal retarder 460 may be separately disposed from the photosensitive unit 500 .

[0086] Form 2: Figure 8 As shown, when the polarization device 400 includes a first linear polarizer 450 and a liquid crystal retarder 460, the photosensitive unit 500 forms an image sensor through packaging, and the liquid crystal retarder 460 is attached to the photosensitive surface of the image sensor.

[0087] Form 3: Figure 8 As shown, when the polarization device 400 includes a first linear polarizer 450 and a liquid crystal phase retarder 460, after the photosensitive unit 500 is packaged to form an image sensor, an imaging lens is arranged on the photosensitive side of the image sensor, wherein the first linear polarizer 450 and the liquid crystal phase retarder 460 can be located between the image sensor and the imaging lens (specifically: the first linear polarizer 450 and the liquid crystal phase retarder 460 can be separately arranged from the image sensor and the imaging lens, respectively, or the first linear polarizer 450 can be attached to the light exit surface 210 of the imaging lens). Of course, the first linear polarizer 450 and the liquid crystal phase retarder 460 can also be located on the side of the imaging lens away from the image sensor (specifically: the first linear polarizer 450 and the liquid crystal phase retarder 460 can be separately arranged from the imaging lens, or the liquid crystal phase retarder 460 can be attached to the light incident surface of the imaging lens). In addition, the imaging lens may be located between the first linear polarizer 450 and the liquid crystal phase retarder 460 (specifically: the first linear polarizer 450 and the liquid crystal phase retarder 460 may be separated from the imaging lens, or at least one of the first linear polarizer 450 and the liquid crystal phase retarder 460 may be attached to the surface of the imaging lens).

[0088] Form 4: Figure 8As shown, when the polarization device 400 includes the first linear polarizer 450 and the liquid crystal phase retarder 460, the first linear polarizer 450 and the liquid crystal phase retarder 460 are integrated and packaged together with the photosensitive unit 500 to form an image sensor. For example, the packaging level can be at least the photosensitive unit 500, the pixel circuit (pixel light shielding layer), the liquid crystal phase retarder 460, and the first linear polarizer 450 stacked in sequence. For another example, the packaging level can also be at least the pixel circuit, the photosensitive unit 500, the liquid crystal phase retarder 460, and the first linear polarizer 450. In addition, a microlens array stacked above the first linear polarizer 450 can also be provided in the image sensor.

[0089] Optionally, a filter is also provided on the photosensitive side of the photosensitive unit 500, and the wavelength band of the collected light 300 is the target wavelength band. The filter is used to filter out the light outside the target wavelength band, so as to reduce the interference of stray light. Figures 1 to 6 As shown, the filter may be located between the second linear polarizing plate 600 and the photosensitive unit 500, or the filter may be located on the side of the second linear polarizing plate 600 away from the photosensitive unit 500; Figures 7 to 9 As shown, the filter may also be located between the polarizing device 400 and the photosensitive unit 500, or, the filter may be located on the side of the polarizing device 400 facing away from the photosensitive unit 500, or, when the polarizing device 400 includes a first linear polarizer 450 and a liquid crystal phase retarder 460, the filter may also be located between the first linear polarizer 450 and the liquid crystal phase retarder 460.

[0090] Optionally, the light source 200 in the present application may be an infrared light source 200 or a visible light source 200, wherein the collection light 300 emitted by the infrared light source 200 is a light in the infrared band, and the collection light 300 emitted by the visible light source 200 is a light in the visible light band. When the light source 200 is an infrared light source 200, using it with a filter can not only weaken the perception of the human eye, but also effectively reduce the interference of ambient light.

[0091] Another aspect of the present application is to provide a three-dimensional imaging method which can be applied to the above three-dimensional imaging device, such as Fig.10 As shown, the method includes:

[0092] S10: Controlling the photosensitive unit to receive a plurality of time-sequential polarized lights in a preset time sequence and form a plurality of polarized images, wherein the polarization directions of any two time-sequential polarized lights are different.

[0093] S20: Obtaining polarization information corresponding to each pixel in the photosensitive unit according to the multiple polarization images.

[0094] S30: deriving normal vector information of each micro-element in the target object according to polarization information corresponding to each pixel in the photosensitive unit and a preset mapping relationship between each pixel in the photosensitive unit and each micro-element in the target object.

[0095] S40: deriving three-dimensional contour information of the target object according to normal vector information of each microelement in the target object and position information of each pixel.

[0096] The photosensitive unit 500 receives each time-series polarized light in sequence in order to generate multiple polarized images. By utilizing the different degree of change of the polarization state of light at each point in the target object, the polarization information can be obtained by comprehensively analyzing multiple polarized images. Specifically, the polarized image is corresponded to each pixel of the photosensitive unit 500, so that the polarization information corresponding to each pixel is obtained by comprehensively analyzing the brightness information of multiple polarized images at the same pixel.

[0097] Since the light received by each pixel comes from different positions on the surface of the target object, the normal vector information of each micro-element in the target object is obtained through the preset mapping relationship between each pixel in the photosensitive unit 500 and each micro-element in the target object (different positions in the target object). In this way, the three-dimensional contour information of the target object can be obtained based on the normal vector information of each micro-element in the target object and the position information of each pixel, so as to reconstruct the contour surface of the target object.

[0098] Another aspect of the present application provides a face recognition method, the method comprising:

[0099] S60: Control the photosensitive unit to receive multiple time-sequential polarized lights in a preset time sequence and form multiple polarization images, wherein the collection light emitted by the light source is incident on the photosensitive unit after being reflected by the target object, and the collection light is polarized modulated by the polarization device before entering the photosensitive unit to form multiple time-sequential polarized lights with different polarization directions, and the pixel value of the polarization image contains polarization information corresponding to the contour surface of the target object.

[0100] Since the collected light has been polarized and modulated into multiple sequential polarized lights by the polarization device before being received by the photosensitive unit, the photosensitive unit 500 can receive each sequential polarized light in chronological order to generate multiple polarization images. Taking advantage of the fact that each point in the face (i.e., the target object) has different degrees of change in the polarization state of the light, the pixel value in each polarization image will contain the polarization information to which it belongs, and each polarization information corresponds to the contour surface of the face. In other words, the corresponding contour surface of the face can be represented by multiple polarization images.

[0101] S70: Performing face recognition according to the multiple polarization images and obtaining a face recognition result. The face recognition includes: face matching and / or anti-counterfeiting recognition.

[0102] Because multiple polarization images can represent the corresponding facial contours, multiple polarization images can be used to perform facial recognition, and then obtain facial recognition results. When facial recognition is performed based on multiple polarization images, it can be specifically performed to verify facial matching and / or verify anti-counterfeiting recognition. When facial recognition includes facial matching verification, the facial recognition result corresponds to a result including whether the face matches. Similarly, when facial recognition includes anti-counterfeiting recognition verification, the facial recognition result also corresponds to a result including whether it is a real face or a forged product such as a photo, video, or silicone face mold.

[0103] When verifying face matching, multiple polarization images and base library images can be input into the first neural network model to obtain a result of whether the face matches.

[0104] When verifying anti-counterfeiting identification, multiple polarized images can be input into the second neural network model to obtain the anti-counterfeiting result of whether it is a real face or a forgery such as a photo, video, or silicone mold of a human face.

[0105] The base image is a pre-stored image that represents correct facial information.

[0106] In addition, when performing face recognition, the aforementioned three-dimensional imaging method can be used to obtain three-dimensional contour information of the face from multiple polarized images, and then the face recognition result can be finally obtained through the three-dimensional contour information. Of course, this face recognition method can still include face matching verification and / or anti-counterfeiting recognition verification.

[0107] Another aspect of the embodiments of the present application provides an electronic device, including a device body and any of the above-mentioned three-dimensional imaging devices, wherein the three-dimensional imaging device is located in the device body. The above-mentioned three-dimensional imaging device can better collect information of the target object, and cooperate with the controller in the device body to reconstruct the contour surface of the target object, which helps to improve the recognition accuracy.

[0108] Of course, the aforementioned face recognition method can be applied to the electronic device.

[0109] The electronic device can specifically be a mobile phone, a tablet computer, a television, a laptop computer, a smart home device (for example, a smart air conditioner, a smart refrigerator, a smart speaker, a smart light or a smart curtain, etc.), a wearable electronic device, a vehicle-mounted device (also referred to as a car computer), a virtual reality device, etc. The embodiments of the present application do not impose any restrictions on this.

[0110] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A three-dimensional imaging device, characterized in that: It includes a light source, a polarization device and an image sensor arranged in sequence along the optical path, the image sensor includes a photosensitive unit, the collection light emitted by the light source is reflected by the target object and then incident on the photosensitive unit, and before the collection light is incident on the photosensitive unit, it is time-division polarization modulated by the polarization device to form a plurality of sequential polarized lights with different polarization directions, and the plurality of sequential polarized lights each carry polarization information corresponding to the contour surface of the target object and sequentially incident on the photosensitive unit.

2. The three-dimensional imaging device according to claim 1, characterized in that: The polarization device is located between the light source and the target object. The collected light emitted by the light source is time-divided and polarized by the polarization device to form a plurality of time-sequential polarized lights. After the plurality of time-sequential polarized lights are sequentially reflected by the target object, each carrying polarization information corresponding to the contour surface of the target object sequentially enters the photosensitive unit.

3. The three-dimensional imaging device according to claim 2, characterized in that: The light source has multiple light emitting surfaces, and the polarization device includes multiple polarization elements corresponding to the multiple light emitting surfaces one by one, each polarization element is located at the light emitting side corresponding to the light emitting surface, and among the multiple polarization elements, the polarization directions of any two polarization elements are different.

4. The three-dimensional imaging device according to claim 3, characterized in that: The included angle between the polarization directions of any two of the polarization elements is greater than 10 degrees.

5. The three-dimensional imaging device according to claim 2, characterized in that: The polarization device includes a first linear polarizer and a liquid crystal phase retarder located at the light emitting side of the light source, and the first linear polarizer is located between the light source and the liquid crystal phase retarder.

6. The three-dimensional imaging device according to claim 2, characterized in that: The polarization device comprises a first linear polarizer and a driver which are connected in driving manner, wherein the first linear polarizer is located at the light emitting side of the light source, and the driver is used for driving the first linear polarizer to rotate around the optical axis of the light source.

7. The three-dimensional imaging device according to any one of claims 2 to 6, characterized in that: A second linear polarizer is also arranged between the target object and the photosensitive unit.

8. The three-dimensional imaging device according to claim 7, characterized in that: The second linear polarizer is attached to the photosensitive surface of the image sensor; or the second linear polarizer is integrated into the image sensor.

9. The three-dimensional imaging device according to claim 7, characterized in that: The polarization direction of the second linear polarizer is the same as the polarization direction of one of the plurality of sequential polarized lights.

10. The three-dimensional imaging device according to claim 1, characterized in that: The polarization device is located between the target object and the photosensitive unit. The collection light emitted by the light source assembly is reflected by the target object and then time-dividedly polarized and modulated by the polarization device to form a plurality of sequential polarized lights. Each of the plurality of sequential polarized lights carries polarization information corresponding to the contour surface of the target object and sequentially enters the photosensitive unit.

11. The three-dimensional imaging device according to claim 10, characterized in that: The polarization device includes a first linear polarizer and a liquid crystal phase retarder located on the photosensitive side of the photosensitive unit, and the liquid crystal phase retarder is located between the first linear polarizer and the photosensitive unit.

12. The three-dimensional imaging device according to claim 10, characterized in that: The polarization device comprises a first linear polarizer and a driver which are connected in driving manner, wherein the first linear polarizer is located at the photosensitive side of the photosensitive unit, and the driver is used for driving the first linear polarizer to rotate around the optical axis of the photosensitive unit.

13. The three-dimensional imaging device according to any one of claims 10 to 12, characterized in that: A second linear polarizer is also arranged between the light source and the target object.

14. The three-dimensional imaging device according to claim 13, characterized in that: The polarization direction of the second linear polarizer is the same as the polarization direction of one of the plurality of sequential polarized lights.

15. A three-dimensional imaging method, characterized in that: The method comprises: Controlling the photosensitive unit to receive a plurality of time-sequential polarized lights in a preset time sequence and form a plurality of polarized images, wherein the polarization directions of any two of the time-sequential polarized lights are different; Obtaining polarization information corresponding to each pixel in the photosensitive unit according to the plurality of polarization images; Determining normal vector information of each micro-element in the target object according to polarization information corresponding to each pixel in the photosensitive unit and a preset mapping relationship between each pixel in the photosensitive unit and each micro-element in the target object; The three-dimensional contour information of the target object is obtained according to the normal vector information of each micro-element in the target object and the position information of each pixel.

16. A face recognition method, characterized in that: The method comprises: Controlling the photosensitive unit to receive a plurality of sequential polarized lights in a preset time sequence and form a plurality of polarized images, wherein the collection light emitted by the light source is incident on the photosensitive unit after being reflected by the target object, and before the collection light is incident on the photosensitive unit, it is polarized modulated by the polarization device in a time-sharing manner to form a plurality of sequential polarized lights with different polarization directions, and the pixel value of the polarized image contains polarization information corresponding to the contour surface of the target object; Face recognition is performed based on the multiple polarization images to obtain a face recognition result, wherein the face recognition includes: face matching and / or anti-counterfeiting recognition.

17. An electronic device, characterized in that: It comprises an equipment body and a three-dimensional imaging device as claimed in any one of claims 1 to 14, wherein the three-dimensional imaging device is located in the equipment body.

Images