Camera module for palm recognition device and palm recognition device

Abstract

A camera module for a palm recognition device and a palm recognition device. The camera module for a palm recognition device comprises a lens module (1) and an image sensor (2). The lens module (1) comprises a lens barrel (11), a first lens assembly (12), and a second lens assembly (13). The first lens assembly (12) comprises plastic lenses (121) and / or spherical glass lenses (122). The first lens assembly (13) comprises free-form lenses (131) and / or molded glass lenses (132). The first lens assembly (12), the second lens assembly (13) and the image sensor (2) are fixed inside the lens barrel (11), and the image sensor (2) is located on the image side of the first lens assembly (12) and the second lens assembly (13).

Description

Palm recognition device camera module and palm recognition device

[0001] This disclosure claims priority to Chinese patent application No. 202420092238.0 filed on January 12, 2024, with utility model name “Palm swiping recognition device camera module,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to the field of optical technology, and in particular to a palm recognition device camera module and a palm recognition device. Background Art

[0003] The palm recognition device can obtain the user's palm image and then confirm the user's identity by identifying the palm features.

[0004] In related technologies, when using a palm recognition device, the user needs to place their hand above the device's camera module, and the palm generally needs to be 5cm-15cm away from the camera module to enable the palm recognition device to obtain a clear palm image. If the palm is too close to the camera module, it will be difficult for the palm recognition device to obtain a complete palm image, making it difficult for the palm recognition device to identify the user.

[0005] Summary of the Invention

[0006] In a first aspect, the present disclosure provides a camera module for a palm recognition device. The camera module comprises a lens module and an image sensor;

[0007] The lens module comprises a lens barrel, a first lens assembly and a second lens assembly, wherein the first lens assembly comprises a plastic lens and / or a spherical glass lens, and the second lens assembly comprises a free-form surface lens and / or a molded glass lens;

[0008] The first lens assembly, the second lens assembly and the image sensor are fixed inside the lens barrel, and the image sensor is located on the image side of the first lens assembly and the second lens assembly.

[0009] In a second aspect, the present disclosure provides a palm recognition device, which includes the palm recognition device camera module described in the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG1 is a schematic structural diagram of a camera module of a palm recognition device according to an embodiment of the present disclosure;

[0011] FIG2 is a structural diagram of a camera module of a palm recognition device shown in an embodiment of the present disclosure;

[0012] FIG3 is a structural diagram of a camera module of a palm recognition device shown in an embodiment of the present disclosure;

[0013] FIG4 is a schematic structural diagram of a lens module according to an embodiment of the present disclosure;

[0014] FIG5 is a structural diagram of a lens module shown in an embodiment of the present disclosure;

[0015] FIG6 is a structural diagram of a lens module shown in an embodiment of the present disclosure;

[0016] FIG7 is a structural diagram of a lens module shown in an embodiment of the present disclosure;

[0017] FIG8 is a structural diagram of a camera module of a palm recognition device shown in an embodiment of the present disclosure;

[0018] FIG9 is a schematic diagram of an arrangement of two lens modules according to an embodiment of the present disclosure;

[0019] FIG10 is a schematic diagram of an arrangement of two lens modules according to an embodiment of the present disclosure;

[0020] FIG11 is a schematic diagram of an arrangement of two lens modules according to an embodiment of the present disclosure;

[0021] FIG12 is a schematic diagram of an arrangement of two lens modules according to an embodiment of the present disclosure;

[0022] FIG13 is a schematic structural diagram of a lens module according to an embodiment of the present disclosure.

[0023] Legend:

[0024] 1. Lens module, 11. Lens barrel, 12. First lens assembly, 121. Plastic lens, 122. Spherical glass lens, 13. Second lens assembly, 131. Free-form surface lens, 132. Molded glass lens, 14. Infrared filter film, 15. Anti-reflection film, 1a. Visible light lens module, 1b. Infrared lens module;

[0025] 2. Image sensor. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0027] The terms used in the embodiments of the present disclosure are intended only to explain the embodiments of the present disclosure and are not intended to limit the present disclosure. Unless otherwise defined, technical or scientific terms used herein should have the same ordinary meaning as those of ordinary skill in the art to which the present disclosure pertains. The terms "first," "second," "third," and similar terms used in the patent specification and claims of the present disclosure do not denote any order, quantity, or importance, but are merely used to distinguish between different components. Similarly, terms such as "a" or "an" do not denote a limitation on quantity, but rather denote the presence of at least one. Terms such as "include" or "comprising" mean that the elements or objects preceding the term "include" or "comprising" include the elements or objects listed after the term and their equivalents, and do not exclude other elements or objects. Terms such as "connected" or "connected" are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0028] Contactless palm recognition and payment has been proven to be a popular method for users. It is more convenient than traditional card swiping and QR code scanning, and more secure than other biometric methods such as facial recognition. Based on a large number of user statistics, when using palm recognition devices, the distance between the user's palm and the lens module (also known as the camera module) is typically 3cm-5cm.

[0029] However, the FOV (Field of View) of the camera module in related technologies is relatively small. When using a palm recognition device, the user's palm must be 5-15 cm away from the lens module. If the palm is 3 cm away from the lens module, the palm recognition device cannot capture a complete palm image.

[0030] In related technologies, some palm recognition devices have their lens modules lowered to increase the distance between the palm and the lens module. However, this results in a larger overall size for the palm recognition device and makes the exterior of the lens module susceptible to dust accumulation. The groove formed by the lowered lens module is prone to dust accumulation. Therefore, if the camera module wants to capture close-up images of the palm without changing the position of the lens module, a wide-angle lens module should be used, increasing the lens module's field of view. However, traditional wide-angle lenses have significant distortion and low clarity, making them unable to meet the requirements of palm recognition photography.

[0031] In view of the above technical problems, embodiments of the present disclosure provide a camera module for a palm recognition device. As shown in Figures 1-3, the camera module includes a lens module 1 and an image sensor 2. The lens module 1 includes a lens barrel 11, a first lens assembly 12, and a second lens assembly 13. The first lens assembly 12 includes a plastic lens 121 and / or a spherical glass lens 122, and the second lens assembly 13 includes a free-form lens 131 and / or a molded glass lens 132. The first lens assembly 12, the second lens assembly 13, and the image sensor 2 are fixed inside the lens barrel 11, with the image sensor 2 located on the image side of the first and second lens assemblies 12, 13.

[0032] The first lens assembly 12 may include only the plastic lens 121, only the spherical glass lens 122, or both the plastic lens 121 and the spherical glass lens 122 (as shown in FIG4 ). The disclosed embodiment does not specifically limit the number and arrangement of the plastic lens 121 and the spherical glass lens 122.

[0033] The second lens assembly 13 may include only the free-form surface lens 131 (as shown in FIG1 ), or only the molded glass lens 132 (as shown in FIG2 ), or may include both the free-form surface lens 131 and the molded glass lens 132 (as shown in FIG3 ).

[0034] Plastic lenses can also be called P (Plastic) lenses, spherical glass lenses can also be called G (Glass) lenses, molded glass lenses can also be called GM (Glass Moding) lenses, and free-form lenses can also be called FreeForm lenses.

[0035] The free-form surface lens 131 can increase the field of view of the lens module 1 and improve the distortion of the lens module 1. It can also increase the RI (Relative Illumination) and MTF (Modulation Transfer Function) of the lens module 1, which is beneficial to improving image quality.

[0036] The molded glass lens 132 has the advantages of good thermal stability, high refractive index, low dispersion, high perspective, distortion elimination and expanded field of view, so that while increasing the field of view angle of the lens module 1, it can also reduce the distortion of the lens module 1. The molded glass lens 132 is also beneficial for the use of the camera module of the palm swiping recognition device under more harsh conditions. In addition, the traditional glass lens manufacturing technology requires complicated steps, such as rough grinding, fine grinding, polishing, etc., and the time spent is relatively increased. The production of the molded glass lens 132 only requires a glass preform, and the finished product can be pressed directly by molding, so it is very suitable for mass production. Therefore, the use of the molded glass lens 132 in the camera module of the palm swiping recognition device can improve production efficiency and is beneficial to the mass production of the camera module of the palm swiping recognition device.

[0037] It should be noted that the lens module 1 and image sensor 2 in the embodiment of the present disclosure can also be used in a face recognition module.

[0038] According to the technical solution provided by the embodiment of the present disclosure, the lens module 1 in the camera module of the palm swiping recognition device includes a first lens assembly 12 and a second lens assembly 13. The second lens assembly 13 is a free-form surface lens 131 or a molded glass lens 132, or the second lens assembly 13 includes a free-form surface lens 131 and a molded glass lens 132. Both the free-form surface lens 131 and the molded glass lens 132 can increase the field of view of the lens module 1. Therefore, when the lens module 1 is used to shoot the palm, if the palm is close to the lens module 1 or the palm is slightly offset, the lens module 1 can also obtain a complete palm image. At the same time, both the free-form surface lens 131 and the molded glass lens 132 can improve the distortion of the lens module 1, so that the distortion of the lens module 1 is smaller and the clarity is improved, thereby avoiding the distortion of the image obtained by the lens module 1, which is conducive to obtaining a clear palm image. In this way, when the palm is close to the lens module 1, the camera module of the palm swiping recognition device (i.e., the image sensor 2) can obtain a complete and clear image, which is conducive to the camera module of the palm swiping recognition device to quickly and accurately identify the user's identity.

[0039] According to calculations, when the second lens assembly 13 includes the free-form surface lens 131 and the molded glass lens 132 , the horizontal viewing angle of the lens module 1 can reach 125°-135°, and the vertical viewing angle can reach 115°-125°.

[0040] In some examples, the free-form surface lens 131 has 30 to 80 degrees of freedom. In related art, the maximum degree of freedom for a free-form surface lens is 40. The free-form surface lens 131 provided by the presently disclosed embodiments has a greater degree of freedom, thereby significantly improving the distortion of the lens module 1. In some examples, the free-form surface lens 131 has more than 40 degrees of freedom. The degrees of freedom of the free-form surface lens 131 refer to the number of adjustable variables or parameters in the surface equation used to describe the curved shape of the free-form surface lens 131.

[0041] Experiments show that the horizontal distortion rate of lens module 1 is -13.3% and the vertical distortion rate is -6.6%. Compared to the -35% horizontal distortion rate and -22% vertical distortion rate of lens modules in traditional palm recognition devices, the distortion rate of lens module 1 in the disclosed embodiment is significantly reduced. This allows the palm image captured by lens module 1 to be clearer.

[0042] In some examples, as shown in Figures 1 and 3, the free-form surface lens 131 is located on the image side of the first lens assembly 12. When assembling the lens module 1, the lenses are placed starting from the object side of the lens module 1 and gradually arranged toward the image side. Placing the free-form surface lens 131 on the image side of the first lens assembly 12 ensures that it is installed last. This prevents collisions between the free-form surface lens 131 and other lenses during installation. Furthermore, the first lens assembly 12 can converge light. Placing the free-form surface lens 131 on the image side of the first lens assembly 12 allows for the maximum possible convergence of light onto the free-form surface lens 131, facilitating its light regulation. The free-form surface lens 131 is the lens closest to the image sensor 2 among the multiple lenses in the second lens assembly 13. Because the free-form surface lens 131 has relatively weak structural strength, placing it closest to the image sensor 2 provides protection for the free-form surface lens 131. When the camera module of the palm swiping recognition device is bumped, the free-form surface lens 131 is not easily damaged.

[0043] Of course, in other examples, the free-form surface lens 131 may also be located on the object side of the first lens assembly 12. Alternatively, when the first lens assembly 12 includes multiple lenses, the free-form surface lens 131 may also be located inside the first lens assembly 12, that is, between the multiple lenses of the first lens assembly 12, which is not specifically limited in the present embodiment.

[0044] In some examples, as shown in Figures 5 and 6, the number of free-form surface lenses 131 can be one or more, and the present disclosure does not limit the number of free-form surface lenses 131. The multiple free-form surface lenses 131 can be arranged adjacent to each other in sequence, or can be arranged alternately with the multiple lenses of the first lens assembly 12.

[0045] In some examples, the molded glass lens 132 is an aspherical lens, and the degrees of freedom of the molded glass lens 132 are 10-30. The molded glass lens 132 can increase the field of view of the lens module 1 and can also reduce the distortion of the lens module 1. The degrees of freedom of the molded glass lens 132 in the lens module in the related art are usually 16. The degrees of freedom of the molded glass lens 132 provided in the embodiment of the present disclosure are larger, which is conducive to further improving the field of view of the lens module 1 and reducing the distortion of the lens module 1. Among them, in some examples, the degrees of freedom of the molded glass lens 132 are greater than 16. Among them, the degrees of freedom of the molded glass lens 132 refer to the number of adjustable variables or parameters in the surface equation used to describe the curved shape of the molded glass lens 132.

[0046] Ordinary spherical glass can cause defocus due to spherical chromatic aberration, but aspherical lenses can compensate for this deficiency by eliminating spherical chromatic aberration. Furthermore, optical imaging requires two or more spherical lenses, which can be replaced with a single aspherical lens. This reduces the number of lenses in lens module 1.

[0047] In some examples, the molded glass lens 132 is located between the multiple lenses included in the first lens assembly 12 , so that the molded glass lens 132 can play a supporting role on the lens barrel 11 .

[0048] In some examples, as shown in FIG3 , the first lens assembly 12 includes three plastic lenses 121. The second lens assembly 13 includes a molded glass lens 132. The molded glass lens 132 has two plastic lenses 121 on its object side and one plastic lens 121 on its image side. The two plastic lenses 121, one molded glass lens 132, one plastic lens 121, and one free-form surface lens 131 are arranged in sequence. Placing the molded glass lens 132 in the middle of the multiple lenses can provide good support for the lens barrel 11.

[0049] In other examples, as shown in FIG4 , the first lens assembly 12 may also include two plastic lenses 121 and one spherical glass lens 122. The molded glass lens 132 has two plastic lenses 121 on the object side and one spherical glass lens 122 on the image side. The two plastic lenses 121, the molded glass lens 132, the spherical glass lens 122, the free-form surface lens 131, and the image sensor 2 are sequentially arranged along the axial direction of the lens barrel 11. The presently disclosed embodiments do not specifically limit the number or type of lenses in the first lens assembly 12, nor the relative positions of the first lens assembly 12 and the molded glass lens 132.

[0050] In some examples, as shown in FIG. 3 , the second lens assembly 13 includes a free-form surface lens 131 and a molded glass lens 132 , and the free-form surface lens 131 is located on the image side of the molded glass lens 132 .

[0051] In other examples, as shown in FIG. 6 and FIG. 7 , the free-form surface lens 131 may be located on the object side of the molded glass lens 132 .

[0052] As shown in Figures 2-7 , the disclosed embodiments do not specifically limit the number or arrangement of the plastic lens 121, spherical glass lens 122, free-form surface lens 131, and molded glass lens 132. The plastic lens 121, spherical glass lens 122, free-form surface lens 131, and / or molded glass lens 132 can be arranged in any combination.

[0053] Because the lens module 1 provided in the embodiments of the present disclosure has a wide field of view, more light sources enter the lens module 1, making it more susceptible to glare. This means that light spots are likely to appear on the palm image captured by the lens module 1. These spots can obscure some palm features, making it difficult for the palm recognition device to identify the user. To reduce glare from the lens module 1, in some examples, the inner wall of the lens barrel 11 is coated with an anti-glare coating, such as ink. This anti-glare coating absorbs some light, preventing the palm image from being obscured by the light spots, and facilitating user identification by the palm recognition device.

[0054] In some examples, the lens module 1 is an infrared lens module 1b. As shown in FIG8 , the lens module 1 further includes an infrared filter 14 located on the object side of the image sensor 2. The infrared filter 14 is configured to transmit infrared light and absorb visible light.

[0055] Accordingly, the image sensor 2 is an infrared image sensor. Thus, when the surrounding environment is dark, the lens module 1 can capture an infrared image of the palm, which is beneficial for the palm recognition device to obtain palm features in a dark environment.

[0056] In some examples, when the lens module 1 is a visible light lens module 1a, the lens module 1 may also have a filter for filtering infrared light and transmitting visible light.

[0057] In some examples, as shown in FIG9 , the camera module of the palm swiping recognition device includes two lens modules 1. One lens module 1 is a visible light lens module 1a, which is used to transmit visible light, and the other lens module 1 is an infrared light lens module 1b, which is used to transmit infrared light. Accordingly, the camera module of the palm swiping recognition device includes two image sensors 2. One image sensor 2 is a color image sensor, and is opposite to the visible light lens module 1a, and is used to receive the visible light transmitted by the visible light lens module 1a to form a color image. The other image sensor 2 is an infrared image sensor, and is opposite to the infrared light lens module 1b, and is used to receive the infrared light transmitted by the infrared lens module 1b to form a black and white image. When the two lens modules 1 are used at the same time, more palm features can be captured, which is conducive to the palm swiping recognition device to quickly identify the user's identity.

[0058] It should be noted that the types, quantities and arrangements of the lenses in the visible light lens module 1a and the infrared light lens module 1b may be the same or different.

[0059] In some examples, as shown in Figures 9-12, two lens modules 1 are arranged along the first direction shown. The aspect ratio of the overlapping field of view of the infrared lens module 1b and the visible light lens module 1a is the aspect ratio of the final palm image. Arranging the two lens modules 1 in this manner can achieve an aspect ratio of 4:3 for the palm image. This allows the image captured by the palm recognition device's camera module to more closely resemble the proportions of the palm center, making it easier to obtain a complete palm image when the palm is close.

[0060] It should be noted that for a palm recognition device camera module comprising a visible light lens module 1a and an infrared lens module 1b, the field of view of the camera module is the overlapping area of ​​the visible light lens module 1a and the infrared lens module 1b. For example, as shown in Figures 11 and 12, the field of view of the visible light lens module 1a is rectangular area ABCD, and the field of view of the infrared lens module 1b is rectangular area MNPQ. The field of view of the camera module is then the overlapping area of ​​rectangular area ABCD and rectangular area MNPQ, i.e., rectangular area MNCD.

[0061] It has been experimentally measured that when the aspect ratio (or length-to-width ratio) of the rectangular area MNCD is 4:3, the image quality obtained by the camera module of the palm recognition device is higher. Therefore, the aspect ratio of the rectangular area MNCD can be set to 4:3. The aspect ratio of the field of view area of ​​the visible light lens module 1a and the infrared light lens module 1b provided in the embodiment of the present disclosure is generally X:3, that is, BC:AB=X:3, NP:MN=X:3, where X is greater than 4, for example, 5. Therefore, if you want to obtain an overlapping area with an aspect ratio of 4:3, it is necessary to arrange the rectangular area ABCD and the rectangular area MNPQ along the length direction of the rectangular area ABCD (or the rectangular area MNPQ), and the length direction is the first direction mentioned above. In this way, compared with the rectangular area ABCD (or the rectangular area MNPQ), the length of the overlapping rectangular area MNCD is reduced while the width remains unchanged, so that the aspect ratio of the rectangular area MNCD can reach 4:3.

[0062] Of course, in other examples, the two lens modules 1 may also be arranged in other ways according to actual needs, and the embodiments of the present disclosure do not specifically limit this.

[0063] In some examples, as shown in FIG13 , the surfaces of the first lens assembly 12 and the second lens assembly 13 have an anti-reflection film 15. The anti-reflection film 15 is used to increase the refraction of the lens module 1 and reduce the reflection, suppress the glare of the lens module 1, and increase the transmittance. This is conducive to the palm swiping recognition device camera module to obtain clearer images. Each lens in the first lens assembly 12 and each lens in the second lens assembly 13 are coated with an anti-reflection film 15. The material of the anti-reflection film 15 can be magnesium fluoride, titanium oxide, lead sulfide, lead selenide, etc. The thickness of the anti-reflection film 15 can be 300nm-500nm. The curvature of the anti-reflection film 15 is the same as the curvature of the lens to which it is attached.

[0064] The present disclosure also provides a palm recognition device, which includes the aforementioned palm recognition device camera module.

[0065] The above descriptions are merely optional embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present disclosure shall be included in the scope of protection of the present disclosure.

Claims

1. A camera module for a palm-sweeping recognition device, the camera module for the palm-sweeping recognition device comprising a lens module (1) and an image sensor (2); The lens module (1) comprises a lens barrel (11), a first lens assembly (12) and a second lens assembly (13), the first lens assembly (12) comprising a plastic lens (121) and / or a spherical glass lens (122), and the second lens assembly (13) comprising a free-form surface lens (131) and / or a molded glass lens (132); The first lens assembly (12), the second lens assembly (13) and the image sensor (2) are fixed inside the lens barrel (11), and the image sensor (2) is located on the image side of the first lens assembly (12) and the second lens assembly (13).

2. The camera module for a palm-sweeping recognition device according to claim 1, wherein the free-form surface lens (131) is located on the image side of the first lens assembly (12), and the free-form surface lens (131) is the lens closest to the image sensor (2) among the multiple lenses of the second lens assembly (13).

3. The camera module for a palm-sweeping recognition device according to claim 1 or 2, wherein the molded glass lens (132) is located between the multiple lenses comprised in the first lens assembly (12).

4. The camera module for a palm-sweeping recognition device according to claim 3, wherein the first lens assembly (12) comprises three of the plastic lenses (121); The second lens assembly (13) comprises the molded glass lens (132), and the object side of the molded glass lens (132) has two of the plastic lenses (121), and the image side has one of the plastic lenses (121).

5. The camera module for a palm-sweeping recognition device according to claim 1 or 2, wherein the first lens assembly (12) comprises two of the plastic lenses (121) and one spherical glass lens (122); The two plastic lenses (121), the molded glass lens (132), the spherical glass lens (122), the free-form surface lens (131) and the image sensor (2) are arranged in sequence along the axial direction of the lens barrel (11).

6. The camera module for a palm-sweeping recognition device according to claim 1 or 2, wherein the degree of freedom of the free-form surface lens (131) is 30 - 80.

7. The camera module for a palm-sweeping recognition device according to claim 1 or 2, wherein the degree of freedom of the molded glass lens (132) is 10 - 30.

8. The camera module for a palm-sweeping recognition device according to claim 1 or 2, wherein the inner wall of the lens barrel (11) has an anti-glare coating.

9. The camera module for a palm-sweeping recognition device according to claim 1 or 2, wherein the camera module for the palm-sweeping recognition device comprises two of the lens modules (1) and two of the image sensors (2); One of the lens modules (1) is a visible light lens module and is opposite to one image sensor (2); Another one of the lens modules (1) is an infrared light lens module and faces another image sensor (2). The infrared lens module further includes an infrared filter (14). The infrared filter (14) is located on the object side of the another image sensor (2), and the infrared filter (14) is configured to transmit infrared light and filter visible light.

10. A palm-sweeping recognition device, the palm-sweeping recognition device includes the palm-sweeping recognition device camera module according to any one of claims 1-9.

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