Fresnel lens, optical system and wearable device

Abstract

The application relates to the technical field of electronic equipment, and discloses a Fresnel lens, an optical system and a wearable device. The Fresnel lens comprises a lens body, the lens body comprises an incident surface and an exit surface, the exit surface is provided with a polarized free curved surface structure and a Fresnel tooth-shaped structure; the polarized free curved surface structure is arranged at the center position of the exit surface, the polarized free curved surface structure is a non-rotationally symmetrical structure, and is used for changing the refraction direction of light passing through the polarized free curved surface structure; and the Fresnel tooth-shaped structure is arranged around the polarized free curved surface structure. The Fresnel lens disclosed by the application can improve optical efficiency and optical sampling accuracy, thereby improving the user experience of consumers.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic devices, in particular to a Fresnel lens, an optical system and a wearable device. BACKGROUND

[0002] With the continuous upgrading of wearable devices on the market, users also have higher requirements for the use performance of wearable devices. At present, wearable devices have the functions of monitoring the heart rate and blood sugar of users, and this function is realized based on an optical system arranged in the wearable device. The specific principle is that the light emitted by the light source is refracted by the Fresnel lens to reach the human skin tissue, and then the reflected light is received after being reflected by the human skin tissue, so as to determine the function status of the user's body. However, the existing Fresnel lens is mostly a rotationally symmetric structure Fresnel lens, so the light distribution is also rotationally symmetric light distribution, which leads to the fact that the Fresnel lens cannot achieve the best optical efficiency and optical sampling accuracy, thereby affecting the user experience of consumers. SUMMARY

[0003] The present application provides a Fresnel lens, an optical system and a wearable device, which can improve the optical efficiency and optical sampling accuracy, thereby improving the user experience of consumers.

[0004] In a first aspect, the present application provides a Fresnel lens, comprising a lens body, the lens body comprising an incident surface and an exit surface, the exit surface being provided with a polarized free-form surface structure and a Fresnel tooth-shaped structure;

[0005] The polarized free-form surface structure is arranged at the center position of the exit surface, and the polarized free-form surface structure is a non-rotationally symmetric structure, so as to change the refraction direction of the light passing through the polarized free-form surface structure.

[0006] The Fresnel tooth-shaped structure is arranged around the polarized free-form surface structure.

[0007] The Fresnel lens provided by the present application uses a non-rotationally symmetric polarized free-form surface structure. The light passes through the polarized free-form surface structure, and the polarized free-form surface structure can make the refraction direction of the light deviate, so that all the light is refracted as much as possible in the same direction, thereby reducing the scattering phenomenon of the light. Since the refraction direction of the light is clear, more light can be received and reflected by the same area of the human skin at the same time, thereby ensuring that more reflected light can be received. This can be beneficial to improve the light efficiency and optical sampling accuracy. When analyzing various parameters of the user's body subsequently, more effective data can be obtained, thereby improving the user experience of consumers.

[0008] In some possible embodiments, the Fresnel tooth structure comprises a first tooth structure and a second tooth structure, the first tooth structure is composed of a plurality of concentrically arranged first arc-shaped tooth rings, and the second tooth structure is composed of a plurality of concentrically arranged second arc-shaped tooth rings.

[0009] The number of the first arc-shaped tooth rings is different from the number of the second arc-shaped tooth rings.

[0010] In some possible embodiments, the first tooth structure and the second tooth structure are located on both sides of the optical axis of the lens body.

[0011] In some possible embodiments, among the plurality of first arc-shaped tooth rings of the first tooth structure, the heights of at least two first arc-shaped tooth rings are different.

[0012] In some possible embodiments, among the plurality of first arc-shaped tooth rings of the first tooth structure, the widths of at least two first arc-shaped tooth rings are different.

[0013] In some possible embodiments, among the plurality of second arc-shaped tooth rings of the second tooth structure, the heights of at least two second arc-shaped tooth rings are different.

[0014] In some possible embodiments, among the plurality of second arc-shaped tooth rings of the second tooth structure, the widths of at least two second arc-shaped tooth rings are different.

[0015] In some possible embodiments, the thickness of the Fresnel lens is less than 1 mm.

[0016] In a second aspect, the present application provides an optical system, comprising a light source device, a skin-reflected energy receiving device, and a Fresnel lens according to any one of the possible embodiments of the first aspect.

[0017] The light source device is configured to emit light, the Fresnel lens is configured to receive the light and refract the light so that the light is received by human skin.

[0018] The skin-reflected energy receiving device is configured to receive the light reflected by the human skin.

[0019] In a third aspect, the present application provides a wearable device comprising the optical system according to the second aspect. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 FIG. 1 is a schematic diagram of a 2D structure of a Fresnel lens according to an embodiment of the present application;

[0021] Figure 2A side view structure diagram of the Fresnel lens in the embodiment of the present application;

[0022] Figure 3 A top view of the Fresnel lens in the embodiment of the present application;

[0023] Figure 4 A design light distribution curve diagram of the optical system applied to the Fresnel lens in the embodiment of the present application;

[0024] Figure 5 A light ray direction diagram of the light ray passing through the Fresnel lens in the embodiment of the present application;

[0025] Figure 6 A light ray direction diagram of the light ray passing through the Fresnel lens in the embodiment of the present application after adding a skin model;

[0026] Figure 7 A structure diagram of the optical system in the embodiment of the present application.

[0027] In the figure:

[0028] 1-Fresnel lens; 2-light source device; 3-skin reflection energy receiving device; 10-lens body; 11-incidence surface; 12-emergence surface; 20-polarization free curved surface structure; 30-Fresnel tooth structure; 31-first tooth structure; 311-first arc-shaped tooth ring; 32-second tooth structure; 321-second arc-shaped tooth ring. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0030] Reference Figures 1 to 3 The Fresnel lens 1 in the embodiment of the present application includes a lens body 10, the lens body 10 has opposite incidence surface 11 and emergence surface 12, light rays can enter the lens body 10 from the incidence surface 11 and be refracted out from the emergence surface 12. The emergence surface 12 is provided with a polarization free curved surface structure 20 and a Fresnel tooth structure 30, wherein the polarization free curved surface structure 20 is a non-rotationally symmetric structure and is arranged at the center position of the emergence surface 12, and the Fresnel tooth structure 30 is arranged at the periphery of the polarization free curved surface structure 20, that is, the Fresnel tooth structure 30 is arranged around the polarization free curved surface structure 20.

[0031] As Figure 2 and Figure 3As shown, the Fresnel tooth structure 30 includes a first tooth structure 31 and a second tooth structure 32, wherein the first tooth structure 31 is composed of a plurality of concentrically arranged first arc-shaped tooth rings 311, and the second tooth structure 32 is composed of a plurality of concentrically arranged second arc-shaped tooth rings 321. Moreover, the number of the first arc-shaped tooth rings 311 in the first tooth structure 31 is different from the number of the second arc-shaped tooth rings 321 in the second tooth structure 32, that is, the Fresnel tooth structure 30 in the embodiment is a special-shaped Fresnel tooth structure of a non-rotationally symmetric structure.

[0032] In the embodiment, as shown, Figure 4 When the non-rotationally symmetric polarized free-form surface structure 20 is arranged on the exit surface 12 of the lens body 10, the light passes through the polarized free-form surface structure 20, and the polarized free-form surface structure 20 can make the refractive direction of the light deviate, so that all the light is refracted as much as possible in the same direction. At the same time, when the non-rotationally symmetric special-shaped Fresnel tooth structure is arranged, the light passes through the Fresnel tooth structure 30, and the non-rotationally symmetric Fresnel tooth structure 30 can make the refractive direction of the light further deviate, and under the cooperation of the polarized free-form surface structure 20, the light refracted by the Fresnel lens 1 can be refracted as much as possible in a specific direction, thereby reducing the scattering phenomenon of the light. Because the refractive direction of the light is clear, more light can be received and reflected by the same area of the human skin at the same time, and then more reflected light can be received, which can be beneficial to improve the optical efficiency and the optical sampling accuracy, and more effective data can be obtained when analyzing various parameters of the user's body in the subsequent analysis, thereby improving the user experience of the consumer.

[0033] In some embodiments, when the polarized free-form surface structure 20 is designed as a non-rotationally symmetric structure, for example, the orthographic projection of the polarized free-form surface structure 20 on the exit surface 12 is a symmetric pattern, but the thickness of the polarized free-form surface structure 20 at the two ends of the optical axis as the symmetric axis is different, so as to realize the non-rotationally symmetric performance of the polarized free-form surface structure 20. Alternatively, the shape of the orthographic projection of the polarized free-form surface structure 20 on the exit surface 12 is an asymmetric shape, so that the non-rotationally symmetric performance of the polarized free-form surface structure 20 can also be realized. Alternatively, other ways can also be used to make the polarized free-form surface structure 20 have the non-rotationally symmetric performance, which is not limited in the embodiment.

[0034] As described above, the number of the first arc-shaped tooth rings 311 and the second arc-shaped tooth rings 321 is different, and the Fresnel tooth structure 30 is arranged around the polarized free-form surface structure 20. As an embodiment, the first tooth structure 31 and the second tooth structure 32 are respectively located on the left and right sides of the optical axis of the lens body 10. Moreover, continuing to refer to Figure 3The first arc-shaped gear ring 311 at the innermost layer and the second arc-shaped gear ring 321 at the innermost layer are adjacent to the polarized free-form surface structure 20, and the first arc-shaped gear ring 311 at the outermost layer and the second arc-shaped gear ring 321 at the outermost layer are attached to the edge of the exit surface 12, so as to ensure that the exit surface 12 is covered by the polarized free-form surface structure 20 and the Fresnel tooth structure 30 as much as possible, so as to further improve the optical efficiency.

[0035] Further, the distance between the two ends of the first arc-shaped gear ring 311 and the two ends of the second arc-shaped gear ring 321 can be adjusted. For example, the ends of the first arc-shaped gear ring 311 are flush with the left end of the polarized free-form surface structure 20, and the ends of the second arc-shaped gear ring 321 are flush with the right end of the polarized free-form surface structure 20. At this time, the distance between the ends of the first arc-shaped gear ring 311 and the ends of the second arc-shaped gear ring 321 is relatively large. Alternatively, the ends of the first arc-shaped gear ring 311 are close to the plane where the optical axis of the lens body 10 is located, and the ends of the second arc-shaped gear ring 321 are close to the plane where the optical axis of the lens body 10 is located. The plane where the optical axis of the lens body 10 is located is a plane perpendicular to the arrangement direction of the first tooth structure 31 and the second tooth structure 32. At this time, the distance between the ends of the first arc-shaped gear ring 311 and the ends of the second arc-shaped gear ring 321 is relatively small. In this embodiment, by designing the distance between the first tooth structure 31 and the second tooth structure 32, different process production requirements of the Fresnel lens 1 can be met.

[0036] In some embodiments, in order to further realize the non-rotationally symmetric characteristic of the Fresnel lens 1, among the plurality of first arc-shaped gear rings 311 of the first tooth structure 31, the heights of at least two first arc-shaped gear rings 311 are different. For example, the first arc-shaped gear rings 311 can include A-type arc-shaped gear rings and B-type arc-shaped gear rings, the heights of the A-type arc-shaped gear rings and the B-type arc-shaped gear rings are different, and the A-type arc-shaped gear rings and the B-type arc-shaped gear rings are arranged alternately, so that the heights of any two adjacent first arc-shaped gear rings 311 are different. For another example, along the direction gradually away from the optical axis of the lens body 10, the heights of the first arc-shaped gear rings 311 gradually decrease or gradually increase. Alternatively, the heights of the first arc-shaped gear rings 311 can be set at will, so that the first tooth structure 31 has a non-rotationally symmetric characteristic.

[0037] In the present embodiment, the widths of at least two of the first arc-shaped toothings 311 in the first tooth structure 31 are not the same. Similarly to the case where the heights of the two first arc-shaped toothings 311 are not the same, for example, the first arc-shaped toothings 311 include A-type arc-shaped toothings and B-type arc-shaped toothings, the widths of the A-type arc-shaped toothings and the B-type arc-shaped toothings are not the same, and the A-type arc-shaped toothings and the B-type arc-shaped toothings are arranged alternately, so that the widths of any two adjacent first arc-shaped toothings 311 are not the same. For another example, the widths of the first arc-shaped toothings 311 gradually decrease or gradually increase in a direction gradually away from the optical axis of the lens body 10. For yet another example, the widths of the first arc-shaped toothings 311 can be set at will, so that the first tooth structure 31 has a non-rotationally symmetrical characteristic.

[0038] In some embodiments, the heights of at least two of the second arc-shaped toothings 321 in the second tooth structure 32 are not the same. For example, the second arc-shaped toothings 321 include C-type arc-shaped toothings and D-type arc-shaped toothings, the heights of the C-type arc-shaped toothings and the D-type arc-shaped toothings are not the same, and the C-type arc-shaped toothings and the D-type arc-shaped toothings are arranged alternately, so that the heights of any two adjacent second arc-shaped toothings 321 are not the same. For another example, the heights of the second arc-shaped toothings 321 gradually decrease or gradually increase in a direction gradually away from the optical axis of the lens body 10. For yet another example, the heights of the second arc-shaped toothings 321 can be set at will, so that the second tooth structure 32 has a non-rotationally symmetrical characteristic.

[0039] In the present embodiment, the widths of at least two of the second arc-shaped toothings 321 in the second tooth structure 32 are not the same. Similarly to the case where the heights of the two second arc-shaped toothings 321 are not the same, for example, the second arc-shaped toothings 321 include C-type arc-shaped toothings and D-type arc-shaped toothings, the widths of the C-type arc-shaped toothings and the D-type arc-shaped toothings are not the same, and the C-type arc-shaped toothings and the D-type arc-shaped toothings are arranged alternately, so that the widths of any two adjacent second arc-shaped toothings 321 are not the same. For another example, the widths of the second arc-shaped toothings 321 gradually decrease or gradually increase in a direction gradually away from the optical axis of the lens body 10. For yet another example, the widths of the second arc-shaped toothings 321 can be set at will, so that the second tooth structure 32 has a non-rotationally symmetrical characteristic.

[0040] Reference is made to Figure 5 and Figure 6 , which are schematic diagrams of the light ray paths of the Fresnel lens 1 in the present embodiment, and Figure 5 and Figure 6 , where the line L1 represents the light ray path of a conventional Fresnel lens 1, and the line L2 represents the light ray path of the Fresnel lens 1 in the present embodiment. As shown in the diagrams, the light rays of the conventional Fresnel lens 1 are concentrated on the surface of the skin model, while the light rays of the Fresnel lens 1 in the present embodiment are concentrated on the surface of the skin model and the surface of the skin model is not damaged.Figure 5 And Figure 6 It can be seen that, when the Fresnel lens 1 in the embodiment of the present application is adopted, the refractive direction of the light is offset, so that more light can be emitted in the same direction.

[0041] Referring to Table 1 and Table 2, Table 1 is the data of the photoelectric parameters of the product using the conventional Fresnel lens, and Table 2 is the data of the photoelectric parameters of the product using the Fresnel lens in the embodiment of the present application.

[0042]

[0043] Table 1

[0044]

[0045] Table 2

[0046] From the comparison of the data in Table 1 and Table 2, it can be seen that, for each type of light source, the light output rate of the Fresnel lens 1 in the embodiment is higher than that of the conventional Fresnel lens, and the PD received radiation power of the Fresnel lens 1 in the embodiment is also higher than that of the conventional Fresnel lens. Therefore, it can be seen that the optical efficiency of the product using the Fresnel lens 1 in the embodiment of the present application has been significantly improved.

[0047] In some embodiments, the thickness of the Fresnel lens 1 in the embodiment is less than 1mm. It can be understood that the Fresnel lens 1 in the embodiment not only improves the optical efficiency, but also realizes the light and thin design of the product, thereby further improving the user experience of consumers.

[0048] Based on the same inventive concept, referring to Figure 7 The embodiment of the present application can also provide an optical system, which comprises a light source device 2, a skin reflected energy receiving device 3 and the Fresnel lens 1 described in the above embodiment. The light emitted by the light source device 2 passes through the Fresnel lens 1, and the light is refracted by the Fresnel lens 1 and is received and reflected by the human skin. The skin reflected energy receiving device 3 is used to receive the light reflected by the human skin.

[0049] The optical system in the embodiment can ensure more light to be emitted to the human skin, so that more light can be received by the skin-reflected energy receiving device 3 when the asymmetric polarized freeform surface structure and the lens structure with special polarized Fresnel tooth shape are used. The skin-reflected energy receiving device 3 can also be used to process the reflected light, so as to calculate various data of the user's physical function. It can be understood that when the light received by the skin-reflected energy receiving device 3 is sufficient, the optical sampling precision is improved, so as to improve the accuracy of data processing, thereby improving the user experience of consumers. In addition, due to the improvement of the optical sampling precision, the product can also achieve the effect of energy saving to a certain extent.

[0050] Based on the same inventive concept, the embodiments of the present application can also provide a wearable device, which comprises the optical system described in the above embodiments. Exemplarily, the wearable device is a smart bracelet or a smart watch.

[0051] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and the equivalent technologies thereof, the present application also intends to include these modifications and variations.

Claims

1. A Fresnel lens, characterized by, The lens body comprises an incident surface and an exit surface, and the exit surface is provided with a polarized free-form surface structure and a Fresnel tooth structure; The polarized free-form surface structure is arranged at the center of the exit surface, and the polarized free-form surface structure is a non-rotationally symmetric structure for changing the refraction direction of light passing through the polarized free-form surface structure, so that the light passing through the polarized free-form surface structure is refracted towards the same direction; The Fresnel tooth structure surrounds the polarized free-form surface structure; The Fresnel tooth structure comprises a first tooth structure and a second tooth structure, the first tooth structure is composed of a plurality of concentrically arranged first arc-shaped tooth rings, and the second tooth structure is composed of a plurality of concentrically arranged second arc-shaped tooth rings; The number of the first arc-shaped tooth rings is different from the number of the second arc-shaped tooth rings; The first tooth structure and the second tooth structure are located on both sides of the optical axis of the lens body.

2. The Fresnel lens according to claim 1, characterized in that Among the plurality of first arc-shaped tooth rings of the first tooth structure, the heights of at least two first arc-shaped tooth rings are different.

3. Fresnel lens according to claim 1 or 2, characterized in that Among the plurality of first arc-shaped tooth rings of the first tooth structure, the widths of at least two first arc-shaped tooth rings are different.

4. The Fresnel lens of claim 1, wherein, Among the plurality of second arc-shaped tooth rings of the second tooth structure, the heights of at least two second arc-shaped tooth rings are different.

5. The Fresnel lens according to claim 1 or 4, characterized in that Among the plurality of second arc-shaped tooth rings of the second tooth structure, the widths of at least two second arc-shaped tooth rings are different.

6. The Fresnel lens of claim 1, wherein, The thickness of the Fresnel lens is less than 1mm.

7. An optical system characterized by comprising: The optical system comprises a light source device, a skin reflected energy receiving device, and the Fresnel lens according to any one of claims 1-6; The light source device is used for emitting light, the Fresnel lens is used for receiving the light and refracting the light, so that the light is received by human skin; The skin reflected energy receiving device is used for receiving the light reflected by the human skin.

8. A wearable device, comprising: The optical system comprises the optical system according to claim 7.

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