Dot matrix projection structure, face recognition module and electronic equipment

Abstract

A dot matrix projection structure comprises an infrared light source, a collimating lens, a semi-transparent and semi-reflective sheet, a diffractive optical element and an infrared light conversion film. The infrared light source is used for emitting infrared light. The collimating lens is used for receiving infrared light from the infrared light source and collimating the infrared light to form parallel light. The semi-transparent and semi-reflective sheet is arranged on the light emitting side of the collimating lens and used for dividing incident light into two parts, one part directly penetrates through the semi-transparent and semi-reflective sheet to be emitted, and the other part is reflected by the semi-transparent and semi-reflective sheet to be emitted. The diffractive optical element is arranged on a light emitting path of the semi-transparent and semi-reflective sheet and used for converting the infrared light into infrared light spots to be emitted. And the infrared light conversion film is arranged on the other light emitting path of the semi-transparent semi-reflective sheet and is used for converting the infrared light into visible light to be emitted. The invention further provides a face recognition module and electronic equipment. The dot matrix projection structure can project infrared light in one direction for face recognition, and can provide visible light in the other direction for providing a light source for an LED lamp or a time electronic screen and the like.

Description

Technical Field

[0001] The present application relates to the field of optics, and in particular to a dot matrix projection structure and a face recognition module and electronic device comprising the dot matrix projection structure. Background Art

[0002] In recent years, with the development of "face recognition" technology, consumer electronic products with face recognition functions have been widely used. Smartphones are representative. In order to realize the face recognition function, the smartphone contains at least devices such as a dot matrix projector and an infrared camera. The dot matrix projector emits multiple light spots (for example, thousands to tens of thousands) and projects them onto the face. The infrared camera receives the changes in the reflected light spots, calculates the surface contour of the virtual face, and compares and analyzes it with the authenticated face information. However, as an important module of face recognition technology, the dot matrix projector currently has a relatively single function and cannot meet the multifunctional requirements of the product. Summary of the invention

[0003] In view of this, the first aspect of the present application provides a dot matrix projection structure, including:

[0004] An infrared light source, used for emitting infrared light;

[0005] A collimating lens, used for receiving the infrared light from the infrared light source and collimating the infrared light to form parallel light;

[0006] A semi-transparent and semi-reflective sheet is arranged on the light-emitting side of the collimating lens, and the semi-transparent and semi-reflective sheet is used to divide the light incident thereon into two parts, one part directly penetrates the semi-transparent and semi-reflective sheet and is emitted, and the other part is reflected by the semi-transparent and semi-reflective sheet and is emitted;

[0007] a diffractive optical element, arranged on a light-emitting path of the semi-transparent and semi-reflective sheet, for converting infrared light into an infrared light spot for emission; and

[0008] The infrared light conversion film is arranged on another light output path of the semi-transmissive and semi-reflective sheet to convert the infrared light into visible light for output.

[0009] The dot matrix projection structure of the first aspect of the present application can project infrared light in a first direction for face recognition and provide visible light in a second direction for providing a light source for an LED lamp or a time electronic screen, etc., by setting a semi-transparent and semi-reflective sheet and an infrared light conversion film. The dot matrix projection structure simplifies the spatial structure and meets the market demand for miniaturization.

[0010] A second aspect of the present application provides a face recognition module, comprising the above-mentioned dot matrix projection structure and an infrared camera, wherein the dot matrix projection structure is used to transmit infrared light, and the infrared camera is used to receive reflected infrared light.

[0011] A third aspect of the present application provides an electronic device, comprising a housing and the above-mentioned face recognition module arranged in the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the dot matrix projection structure of the first embodiment of the present application.

[0013] Figure 2 It is a schematic diagram of a dot matrix projection structure according to the second embodiment of the present application.

[0014] Figure 3 Schematic diagram of a face recognition module according to an embodiment of the present application.

[0015] Figure 4 A schematic diagram of an electronic device according to an embodiment of the present application.

[0016] Description of main component symbols:

[0017] Dot projection structure 100, 200

[0018] Infrared light source 10

[0019] Collimating lens 20

[0020] Total reflection sheet 30

[0021] Diffractive optical element 40

[0022] Semi-transparent and semi-reflective film 50

[0023] Infrared light conversion film 60

[0024] Lens 70

[0025] Front 71

[0026] Back 72

[0027] Side 73

[0028] The first total reflection sheet 31

[0029] The second total reflection sheet 32

[0030] Face recognition module 300

[0031] Infrared camera 310

[0032] Electronic equipment 400

[0033] Housing 410 DETAILED DESCRIPTION

[0034] The present application provides a dot matrix projection structure, which can not only emit infrared light in one direction for face recognition, but also emit non-infrared light (visible light) in another direction to be used as a light source for other modules or structures.

[0035] Embodiment 1

[0036] See also Figure 1 The dot matrix projection structure 100 of the first embodiment includes an infrared light source 10, a collimating lens 20, a total reflection plate 30, a diffractive optical element (DOE) 40, a semi-transmissive and semi-reflective plate 50 and an infrared light conversion film 60.

[0037] The infrared light source 10 is used to emit infrared light. Figure 1 As shown, the collimating lens 20 is spaced apart from the infrared light source 10 and faces the light-emitting surface of the infrared light source 10. The collimating lens 20 is used to receive infrared light from the infrared light source 10 and collimate and converge infrared light beams originally in different directions to form mutually parallel infrared light beams.

[0038] like Figure 1 As shown, the total reflection sheet 30 is arranged on the light-emitting side of the collimating lens 20. The total reflection sheet 30 has a reflection surface for totally reflecting the light incident on the reflection surface to change the propagation direction of the infrared light. In the embodiment of the present application, the reflection surface of the total reflection sheet 30 is at a 45-degree angle to the optical axis direction of the parallel light emitted from the collimating lens 20, but the invention is not limited thereto. In this way, after the parallel light emitted from the collimating lens 20 passes through the total reflection sheet 30, the optical axis direction is changed to be perpendicular to the original parallel light.

[0039] like Figure 1 As shown, the semi-transparent and semi-reflective sheet 50 is arranged in the reflection path of the total reflection sheet 30 to divide the incident light into two parts and emit them from different directions, wherein part of the incident light (for example, about half of the incident light) directly penetrates the semi-transparent and semi-reflective sheet 50 and emits, and the remaining incident light is reflected and emitted by the semi-transparent and semi-reflective sheet 50. The total reflection sheet 30 is arranged between the collimating lens 20 and the semi-transparent and semi-reflective sheet 50. The semi-transparent and semi-reflective sheet 50 can achieve reflection and transmission. In addition, the ratio of infrared light reflected and transmitted by the semi-transparent and semi-reflective sheet 50 can be adjusted and designed according to needs, and it is not necessarily that half of the incident light is reflected and half of the incident light is transmitted.

[0040] In the embodiment of the present application, the semi-transmissive and semi-reflective sheet 50 is arranged in parallel with the total reflection sheet 30, but the present invention is not limited thereto. Thus, after passing through the semi-transmissive and semi-reflective sheet 50, half of the infrared light is reflected and emitted, and half of the infrared light is directly transmitted and emitted, and the optical axis of the infrared light that is reflected and emitted and the optical axis of the infrared light that is directly transmitted and emitted are perpendicular to each other.

[0041] like Figure 1 As shown, the diffractive optical element 40 and the infrared light conversion film 60 are respectively arranged on the two light exit paths of the semi-transparent and semi-reflective sheet 50. In the embodiment of the present application, the diffractive optical element 40 is arranged on the reflection path of the semi-transparent and semi-reflective sheet 50, and the infrared light conversion film 60 is arranged on the transmission path of the semi-transparent and semi-reflective sheet 50, but it is not limited to this. In other embodiments, the diffractive optical element 40 can also be arranged on the transmission path of the semi-transparent and semi-reflective sheet 50, and the infrared light conversion film 60 is arranged on the reflection path of the semi-transparent and semi-reflective sheet 50.

[0042] The diffractive optical element 40 is used to diffract the received light to form multiple (e.g., thousands or tens of thousands) infrared light spots, which are projected onto the surface of an object (e.g., a face) for face recognition. The diffractive optical element 40 usually uses a microstructure to change the phase of the light it propagates. By properly designing the microstructure on the surface of the optical diffraction element, any light with a designed light intensity distribution can be output when a specific light is input.

[0043] The infrared light conversion film 60 is used to convert the infrared light incident thereon into visible light for emission. The visible light emitted by the infrared light conversion film 60 can be used as visible light backlight or as light required by other modules.

[0044] The infrared light conversion film 60 includes a substrate (not shown) and a conversion layer (not shown) located on the surface of the substrate. The substrate may be polystyrene, polyethylene terephthalate, polycarbonate, glass and other materials. In one embodiment, the material of the conversion layer may include organic molecules composed of tin and sulfur and having a diamond-like structure and a diamond-like structure. When near-infrared light is introduced into the compound by a laser, its structure changes the wavelength of the light through a nonlinear interaction process, thereby generating a wavelength of light visible to the human eye. The material is made into a film shape. When infrared light is irradiated onto the film, the material absorbs infrared photons with a longer wavelength and lower energy, and then emits visible light photons with a shorter wavelength and higher energy. According to the law of conservation of energy, the material can only emit one visible light photon after absorbing multiple infrared photons. In another embodiment, the conversion layer is composed of silicon oxide microbeads decorated with nano-ions and metal structures.

[0045] like Figure 1 As shown, the dot matrix projection structure 100 also includes a lens 70, which is made of a light-transmitting material, and infrared light can be transmitted inside the lens. The total reflection sheet 30 and the semi-transparent and semi-reflective sheet 50 are both embedded in the lens 70, and the collimating lens 20, the diffractive optical element 40, and the infrared light conversion film 60 are attached to the outer surface of the lens 70.

[0046] like Figure 1As shown, in this embodiment, the outer surface of the lens 70 includes a front surface 71, a back surface 72 parallel to and opposite to the front surface 71, and a side surface 73 connected between the front surface 71 and the back surface 72. The infrared light source 10 is arranged on the side of the back surface 72 of the lens 70 and is spaced from the back surface 72. The collimating lens 20 is attached to the back surface 72 of the lens 70 and is spaced from the infrared light source 10. The total reflection sheet 30 and the semi-transparent and semi-reflective sheet 50 are arranged in parallel and spaced in the lens 70, and are obliquely arranged between the front surface 71 and the back surface 72. The infrared light conversion film 60 is attached to the side surface 73 of the lens 70, and the diffractive optical element 40 is attached to the front surface 71 of the lens 70. In this way, the infrared spot passing through the diffractive optical element 40 is emitted from the front surface 71 of the lens 70, and the visible light converted by the infrared light conversion film 60 is emitted from the side surface 73 of the lens 70, thereby realizing the function of bidirectional projection of the front surface 71 and the side surface 73 of the lens.

[0047] Embodiment 2

[0048] See also Figure 2 The dot matrix projection structure 200 of the second embodiment also includes an infrared light source 10, a collimating lens 20, a total reflection sheet, a diffractive optical element 40, a semi-transmissive and semi-reflective sheet 50, and an infrared light conversion film 60. The difference from the first embodiment is that the dot matrix projection structure 200 of the second embodiment is provided with two total reflection sheets, namely a first total reflection sheet 31 and a second total reflection sheet 32.

[0049] like Figure 2 As shown, the collimating lens 20 is located on the light output path of the infrared light source 10 , and is used to receive the infrared light from the infrared light source 10 and collimate and converge the infrared light originally in different directions to form parallel light.

[0050] like Figure 2 As shown, the first total reflection sheet 31 is arranged on the light-emitting side of the collimating lens 20 to totally reflect the parallel light to change the propagation direction of the infrared light. In the embodiment of the present application, the reflection surface of the first total reflection sheet 31 is at a 45-degree angle to the optical axis direction of the parallel light emitted by the collimating lens 20, but the present invention is not limited thereto.

[0051] like Figure 2 As shown, the semi-transparent and semi-reflective sheet 50 is arranged in the reflection path of the first total reflection sheet 31 to divide the incident light into two parts and emit them from different directions, for example, about half of the incident light directly penetrates the semi-transparent and semi-reflective sheet 50 and emits, and the remaining about half of the incident light is reflected and emitted. In the embodiment of the present application, the semi-transparent and semi-reflective sheet 50 is arranged parallel to the first total reflection sheet 31, but it is not limited to this.

[0052] like Figure 2As shown, in the embodiment of the present application, the diffractive optical element 40 is arranged on the reflection path of the semi-transmissive and semi-reflective sheet 50, and the infrared light conversion film 60 and the second total reflection sheet 32 ​​are arranged in sequence on the transmission path of the semi-transmissive and semi-reflective sheet 50, but the invention is not limited thereto. The infrared light conversion film 60 is located between the infrared light conversion film 60 and the second total reflection sheet 32. In this way, the light transmitted by the semi-transmissive and semi-reflective sheet 50 is converted into other light (such as visible light) by the infrared light conversion film 60 and then emitted, and then reaches the reflection surface of the second total reflection sheet 32 ​​and is reflected and emitted.

[0053] It can be understood that in the second embodiment, the position of the infrared light conversion film 60 can be adjusted, and it is no longer located between the infrared light conversion film 60 and the second total reflection sheet 32. For example, the infrared light conversion film 60 is arranged on the light exit path of the second total reflection sheet 32, that is, the second total reflection sheet 32 ​​is arranged between the semi-transmissive semi-reflective sheet 50 and the infrared light conversion film 60. The light transmitted by the semi-transmissive semi-reflective sheet 50 is reflected and emitted by the second total reflection sheet 32, and then reaches the infrared light conversion film 60 to be converted into visible light and emitted.

[0054] like Figure 2 As shown, the dot matrix projection structure further includes a lens 70, which is made of a light-transmitting material. The first total reflection sheet 31, the second total reflection sheet 32, the semi-transparent semi-reflective sheet 50, and the infrared light conversion film 60 are all embedded in the lens 70, and the collimating lens 20 and the diffractive optical element 40 are attached to the outer surface of the lens 70.

[0055] like Figure 2 As shown, in this embodiment, the outer surface of the lens 70 includes a front surface 71, a back surface 72 parallel to and opposite to the front surface 71, and a side surface 73 connected between the front surface 71 and the back surface 72. The infrared light source 10 is arranged on the side of the back surface 72 of the lens 70 and is spaced from the back surface 72. The collimating lens 20 is attached to the back surface 72 of the lens 70 and is spaced from the infrared light source 10. The first total reflection sheet 31 and the semi-transparent semi-reflection sheet 50 are arranged in parallel and spaced in the lens 70, and are both arranged obliquely between the front surface 71 and the back surface 72; the second total reflection sheet 32 ​​is arranged vertically with the semi-transparent semi-reflection sheet 50, and the infrared light conversion film 60 is located between the semi-transparent semi-reflection sheet 50 and the second total reflection sheet 32, and the infrared light conversion film 60 is at a 45-degree angle with the semi-transparent semi-reflection sheet 50, and the infrared light conversion film 60 is at a 45-degree angle with the second total reflection sheet 32, and the infrared light conversion film 60 is vertically arranged between the front surface 71 and the back surface 72. The diffractive optical element 40 is attached to the front surface 71 of the lens 70. In this way, the infrared light spot passing through the diffractive optical element 40 is emitted from the front side 71 of the lens 70 , and the visible light converted by the infrared light conversion film 60 is emitted from the back side 72 of the lens 70 , thereby realizing the function of bidirectional projection of the front side 71 and the back side 72 of the lens 70 .

[0056] The dot matrix projection structure 100 (200) of the present application can project infrared light for face recognition on the front 71 through the arrangement of the semi-transparent and semi-reflective sheet 50 and the infrared light conversion film 60, and provide visible light on the back 72 or the side 73. The visible light provided by the back 72 or the side 73 is used to provide a light source for an LED lamp or a time electronic screen, etc. The side 73 / back 72 light source is integrated with the front 71 light source structure, thereby simplifying the spatial structure, that is, reducing the volume, and meeting the market demand for miniaturization.

[0057] See also Figure 3 The present application also provides a face recognition module 300, comprising the above-mentioned dot matrix projection structure 100 (200) and an infrared camera 310. The dot matrix projection structure 100 (200) is used to emit infrared light to the object to be detected (such as a face). The infrared camera 310 is used to receive the infrared light reflected back by the object to be detected.

[0058] See also Figure 4 The present application also includes an electronic device 400, including the above-mentioned face recognition module 300. The electronic device 400 includes a housing 410, and the face recognition module 300 is arranged in the housing 410. The electronic device 400 can be a smart phone, a PAD, etc.

[0059] In addition to providing the infrared light spots required for face recognition, the dot matrix projection structure of the present application can also provide visible light, which can be used as the light source of LED lights or electronic screen lights for time display. In this way, the dot matrix projection structure is multifunctional and meets the market's demand for miniaturization.

[0060] The above implementation modes are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the above preferred implementation modes, a person skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A dot matrix projection structure, characterized in that: include: An infrared light source, used for emitting infrared light; A collimating lens, used for receiving the infrared light from the infrared light source and collimating the infrared light to form parallel light; A semi-transparent and semi-reflective sheet is arranged on the light-emitting side of the collimating lens, and the semi-transparent and semi-reflective sheet is used to divide the light incident thereon into two parts, one part directly penetrates the semi-transparent and semi-reflective sheet and is emitted, and the other part is reflected by the semi-transparent and semi-reflective sheet and is emitted; A diffractive optical element is arranged on a light-emitting path of the semi-transparent and semi-reflective sheet to convert infrared light into an infrared light spot for emission; as well as The infrared light conversion film is arranged on another light output path of the semi-transparent and semi-reflective sheet to convert the infrared light into visible light for output.

2. The dot matrix projection structure according to claim 1, characterized in that: The dot matrix projection structure further includes a total reflection sheet, and the total reflection sheet is arranged between the collimating lens and the semi-transparent and semi-reflective sheet.

3. The dot matrix projection structure according to claim 2, characterized in that: The total reflection sheet forms an angle of 45 degrees with the optical axis direction of the parallel light emitted by the collimating lens, and the semi-transmissive and semi-reflective sheet is arranged parallel to the total reflection sheet.

4. The dot matrix projection structure according to claim 1, characterized in that: The dot matrix projection structure also includes a first total reflection sheet and a second total reflection sheet. The first total reflection sheet is arranged between the collimating lens and the semi-transparent semi-reflective sheet, and the second total reflection sheet is arranged on a light exit path of the semi-transparent semi-reflective sheet.

5. The dot matrix projection structure according to claim 4, characterized in that: The infrared light conversion film is located between the semi-transmissive and semi-reflective sheet and the second total reflection sheet.

6. The dot matrix projection structure according to claim 4, characterized in that: The second total reflection sheet is arranged between the semi-transmissive and semi-reflective sheet and the infrared light conversion film.

7. The dot matrix projection structure according to claim 4, characterized in that: The first total reflection sheet forms an angle of 45 degrees with the optical axis direction of the parallel light emitted by the collimating lens, the semi-transparent semi-reflective sheet is arranged parallel to the first total reflection sheet, and the second total reflection sheet is perpendicular to the semi-transparent semi-reflective sheet.

8. The dot matrix projection structure according to claim 1, characterized in that: The diffractive optical element is arranged on the reflected light path of the semi-transparent and semi-reflective sheet, and the infrared light conversion film is arranged on the transmitted light path of the semi-transparent and semi-reflective sheet.

9. A face recognition module, characterized in that: It comprises the dot matrix projection structure and an infrared camera as described in claims 1 to 8, wherein the dot matrix projection structure is used to transmit infrared light, and the infrared camera is used to receive reflected infrared light.

10. An electronic device, characterized in that: The invention comprises a housing and a face recognition module as claimed in claim 9 arranged in the housing.

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