Optical structure, manufacturing method and head-mounted display

Abstract

The invention provides an optical structure, which comprises a first lens, a second lens, a third lens and a fourth lens, and the first lens, the second lens, the third lens and the fourth lens are sequentially arranged along the optical axis direction of the second lens; the second lens comprises a first surface facing the first lens and a second surface facing the third lens, and the first surface is bent towards the first lens; the third lens comprises a third surface, a fourth surface and a fifth surface, an air gap is formed between the third surface and the second surface, the third surface is connected with the fourth surface, a non-zero included angle is formed between the third surface and the fourth surface, the fifth surface is simultaneously connected with the third surface and the fourth surface, and the fourth lens is connected with the fourth surface. The invention also provides a manufacturing method of the optical structure and a head-mounted display.

Description

Technical Field

[0001] The present application relates to an optical structure, a method for manufacturing the optical structure, and a head-mounted display including the optical structure. Background Art

[0002] Augmented Reality (AR) glasses include a display and an imaging optical path. There are many types of optical devices in the imaging optical path, and the distances between different optical devices are large. In addition, the angles and positional relationships between different optical devices need to adapt to the light source of the display. The above angles and positional relationships need to be carefully designed to achieve specific functions. Changes in angles and positional relationships may cause the optical path to fail, resulting in a decrease in the imaging quality of AR glasses. How to minimize the overall size of the imaging optical path while ensuring the imaging quality of AR glasses, thereby reducing the size of AR glasses, is a problem that needs to be solved at present. Summary of the invention

[0003] In a first aspect, the present application provides an optical structure, comprising a first lens, a second lens, a third lens and a fourth lens, wherein the first lens, the second lens, the third lens and the fourth lens are arranged in sequence along the optical axis direction of the second lens; The second lens comprises a first surface facing the first lens and a second surface facing the third lens, and the first surface is curved toward the first lens; The third lens includes a third surface, a fourth surface and a fifth surface, the third surface is connected to the fourth surface and a non-zero angle is formed between the third surface and the fourth surface, the fifth surface is connected to the third surface and the fourth surface at the same time, the fourth lens is connected to the fourth surface, an air gap is formed between the third surface and the second surface, the third surface and the fourth surface are used to totally reflect the image light incident from the fifth surface and guide the image light to the first surface, and the first surface is used to reflect the image light to the fourth lens so that the image light is emitted from the fourth lens.

[0004] When the above optical structure is used in a head-mounted display, the optical structure is located on the optical path of the image light emitted by the display in the head-mounted display. The fifth surface in the optical structure is used to receive the image light. After the image light is incident from the fifth surface, it is reflected by the third surface and the fourth surface in sequence and then incident on the first surface. The first surface reflects the image light again, so that the image light reflected by the first surface can all be emitted from the fourth lens and received by the human eye. That is, in the process of transmitting the image light to the human eye, the optical structure causes the image light to be alternately reflected between the third surface and the fourth surface once, so as to realize the folding of the optical path of the image light, which is beneficial to reduce the overall volume of the optical structure.

[0005] A second aspect of the present application provides a method for manufacturing an optical structure, comprising the following steps: forming a first initial lens, a second initial lens, a third initial lens, and a fourth initial lens by injection molding; Bonding the first initial lens and the second initial lens, and cutting the first initial lens and the second initial lens to form a first lens and a second lens; the second lens comprises a first surface facing the first lens and a second surface opposite to the first surface, and the first surface is curved toward the first lens; Adhere the third initial lens and the fourth initial lens, and cut the third initial lens and the fourth initial lens to form a third lens and a fourth lens, wherein the third lens comprises a third surface, a fourth surface and a fifth surface, the third surface is connected to the fourth surface and a non-zero angle is formed between the third surface and the fourth surface, and the fifth surface is connected to the third surface and the fourth surface at the same time; The first lens and the third lens are bonded, an air gap is formed between the third surface and the second surface, the third surface and the fourth surface are used to totally reflect the image light incident from the fifth surface and guide the image light to the first surface, and the first surface is used to reflect the image light to the fourth lens so that the image light is emitted from the fourth lens.

[0006] With respect to the manufacturing method of the above optical structure, the above optical structure is manufactured, so that the optical structure can achieve all the beneficial effects as described above.

[0007] A third aspect of the present application provides a head mounted display, comprising: The optical structure as described above is located on the optical path of the image light; The display is located on a side of the fifth surface away from the fourth surface, and the image light is incident on the third lens from the fifth surface, passes through the third lens, the second lens, the third lens and the fourth lens in sequence, and is emitted from a surface of the fourth lens away from the third lens.

[0008] For the above-mentioned head mounted display, the above-mentioned optical structure is integrated to achieve all the beneficial effects of the above-mentioned optical structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the three-dimensional structure of the optical structure of an embodiment of the present application.

[0010] Figure 2 for Figure 1 Schematic diagram of the optical structure in the figure.

[0011] Figure 3 for Figure 1 Schematic diagram of the cross-sectional structure along line III-III.

[0012] Figure 4 for Figure 1 Schematic diagram of the cross-sectional structure along the IV-IV section line.

[0013] Figure 5 Schematic diagram of the process of manufacturing the optical structure according to an embodiment of the present application.

[0014] Figure 6 Schematic diagram of the positional relationship between the first initial lens and the second initial lens.

[0015] Figure 7 A schematic structural diagram of a first lens and a second lens formed by cutting a first initial lens and a second initial lens.

[0016] Figure 8 The image light emitted by the display in the head mounted display of the embodiment of the present application is Figure 1 Schematic diagram of the light path when propagating in the optical structure.

[0017] Main component symbols Head mounted display: 1 Optical structure: 100 First lens: 10 Sixth surface: 101 Seventh surface: 102 Raised: 11 Second lens: 20 First surface: 211 Second surface: 212 Third lens: 30 Third surface: 313 Fourth surface: 314 Fifth surface: 315 Fourth lens: 40 Air gap: 50 Two-way breathable film: 60 Optical film: 70 Structural adhesive: 80 Display: 200 Image Light: LS First initial lens: 300 Positioning structure: 301 Second initial lens: 400 The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0018] The present application provides an optical structure, which is mainly used in a head-mounted display (such as AR glasses). The optical structure is combined with a display in the head-mounted display to transmit the image light emitted by the display to the human eye. At the same time, the optical structure can also transmit the external environment light into the head-mounted display, and finally be received by the human eye, thereby integrating the virtual information with the real environment.

[0019] Please also read Figure 1 and Figure 2 The optical structure 100 of the embodiment of the present application includes a first lens 10, a second lens 20, a third lens 30 and a fourth lens 40. The first lens 10, the second lens 20, the third lens 30 and the fourth lens 40 are arranged in sequence along the optical axis direction of the second lens 20. The first lens 10 and the second lens 20 are stacked.

[0020] See also Figure 3 The second lens 20 is a semi-convex lens, including a first surface 211 facing the first lens 10 and a second surface 212 facing the third lens 30, and the first surface 211 is curved toward the first lens 10. The third lens 30 includes a third surface 313, a fourth surface 314 and a fifth surface 315, and an air gap 50 is formed between the third surface 313 and the second surface 212. The third surface 313 and the fourth surface 314 are both planes, and the third surface 313 is connected to the fourth surface 314 and a non-zero angle is formed between the third surface 313 and the fourth surface 314. The fifth surface 315 is located between the third surface 313 and the fourth surface 314, and is connected to the third surface 313 and the fourth surface 314. The fourth lens 40 is connected to the fourth surface 314. The third surface 313 and the fourth surface 314 are used to reflect the image light LS incident on the fifth surface 315 and guide the image light LS to the first surface 211, and the first surface 211 is used to reflect the image light LS to the fourth lens 40 so that the image light LS is emitted from the fourth lens 40. See also Figure 4, the sixth surface 101 of the first lens 10 facing the second lens 20 is a concave surface to adapt to the shape of the first surface 211. The edge of the sixth surface 101 is provided with a plurality of protrusions 11 extending toward the third lens 30 at intervals. The projection area of ​​the second lens 20 falling on the first lens 10 does not overlap with the plurality of protrusions 11, that is, the inner edge of each protrusion 11 does not contact the second lens 20. Along the optical axis direction of the second lens 20, each protrusion 11 extends in a direction away from the first lens 10, and the thickness of each protrusion 11 exceeds the second surface 212. When the first lens 10 and the third lens 30 are connected, each protrusion 11 and the edge of the third surface 313 on the third lens 30 are mutually abutted. Since the thickness of each protrusion 11 exceeds the second surface 212, the second lens 20 is located in the space enclosed by the first lens 10 and the third lens 30, and an air gap 50 is formed between the third surface 313 and the second surface 212.

[0021] The refractive index of the third lens 30 is greater than the refractive index of air. When the image light LS incident from the fifth surface 315 is incident on the third surface 313, the incident angle of the image light LS is greater than or equal to the total reflection angle on the third surface 313, so that the image light LS is totally reflected on the third surface 313. In this embodiment, along the optical axis direction of the second lens 20, the thickness of each protrusion 11 may range from 0.25 to 0.35 mm (including the end value), and the thickness of the air gap 50 may range from 100±45 μm (including the end value). In the direction perpendicular to the optical axis of the second lens 20, the width of each protrusion 11 may be 1.5 mm.

[0022] Please refer to Figure 3 In this embodiment, the first lens 10 and the third lens 30 are connected by a structural adhesive 80. The structural adhesive 80 has a high bonding strength, so that the bonding point of the first lens 10 and the third lens 30 can withstand a large load. When the thickness of the structural adhesive 80 along the optical axis direction of the second lens 20 is 0.6 mm, and the width of the structural adhesive 80 perpendicular to the optical axis direction of the second lens 20 is 1.2 mm, the maximum pressure that the bonding point of the first lens 10 and the third lens 30 can withstand is 30 MPa.

[0023] The optical structure 100 further includes a two-way breathable film 60, which is respectively connected to the second lens 20, the third lens 30 and the structural adhesive 80. The two-way breathable film 60 is used to keep the airflow in the air gap 50 and the airflow outside the optical structure 100 unblocked, so that the air pressure in the air gap 50 is consistent with the air pressure outside the optical structure 100. At the same time, the two-way breathable film 60 is also used to prevent liquid or particles outside the optical structure 100 from entering the air gap 50 and affecting the transmission of light in the air gap 50.

[0024] The seventh surface 102 of the first lens 10 away from the second lens 20 is a plane, and the sixth surface 101 facing the second lens 20 is a concave surface curved toward the seventh surface 102, so the first lens 10 as a whole is thin in the center and thick at the edge. The first surface 211 of the second lens 20 is a convex surface curved toward the first lens 10, and the second surface 212 is a plane, so the second lens 20 is thick in the center and thin at the edge. In this embodiment, the thicker edge area of ​​the first lens 10 (the edge area where a plurality of protrusions 11 are arranged at intervals) covers the thinner edge area of ​​the second lens 20. In this way, when the optical structure 100 is squeezed, the thicker edge area of ​​the first lens 10 can protect the thinner edge area of ​​the second lens 20 to prevent the second lens 20 from being crushed.

[0025] In this embodiment, the first lens 10 and the second lens 20 are connected by optical liquid adhesive, and the optical liquid adhesive is located between the first lens 10 and the second lens 20. The optical liquid adhesive can be LOCA (Liquid Optical Clear Adhesive) optical adhesive, which has good filling performance and can better adapt to uneven surfaces to ensure the bonding effect, so that the first lens 10 and the second lens 20 can be completely bonded. In addition, the optical liquid adhesive has good light transmittance, so the optical liquid adhesive has little effect on the propagation of the image light LS in the optical structure 100.

[0026] In the third lens 30 , the fifth surface 315 is curved in a direction away from the fourth surface 314 , and converges the image light LS incident from the fifth surface 315 , so that more image light LS enters the third lens 30 .

[0027] Please refer to Figure 4 An optical film 70 is disposed between the fourth surface 314 and the fourth lens 40, for reflecting part of the image light LS and transmitting part of the image light LS. The optical film 70 may be a reflective polarizer. When the image light LS is transmitted to the optical film 70, the optical film 70 is used to transmit the image light LS having the same polarization direction as the reflective polarizer, without changing the propagation direction of the image light LS, so that the image light LS is always transmitted forward. The optical film 70 is also used to reflect the image light LS perpendicular to the polarization direction of the reflective polarizer. The image light LS is reflected by the optical film 70 and then transmitted to the first surface 211. After being reflected by the first surface 211, the image light LS is emitted after passing through the second lens 20, the third lens 30 and the fourth lens 40 in sequence.

[0028] The optical film 70 is connected to the third lens 30 and the fourth lens 40 by optical adhesive. In this embodiment, the optical adhesive may be OCA (Optically Clear Adhesive), and the process of bonding the optical film 70 to the third lens 30 and the fourth lens 40 by using OCA is relatively simple.

[0029] The overall volume of the optical structure 100 of the present application is small, and the manufacturing process is simple. When the optical structure 100 is applied to a head-mounted display, after the image light LS emitted by the display in the head-mounted display is incident through the fifth surface 315, it is totally reflected on the third surface 313 and guided to the first surface 211 of the second lens 20, and then reflected from the first surface 211 and sequentially passes through the second lens 20, the third lens 30 and the fourth lens 40, and then emitted from the fourth lens 40, and finally received by the human eye. That is, in the optical structure 100, the image light LS reflected by the first surface 211 can be completely emitted from the fourth lens 40 and received by the human eye.

[0030] In an optical system, the area where light can effectively pass through and produce the expected optical effect is called the "optical effective area", and the "area of ​​the optical effective area" refers to the actual physical area of ​​the area in the optical system that allows light to pass through and produce the expected optical effect. The "non-optical effective area" refers to the area that cannot produce the expected optical effect relative to the optical effective area. For the optical structure 100 of the present application, the expected optical effect that needs to be produced is that the image light LS emitted from the optical structure 100 can be received by the human eye. Therefore, the area of ​​the first surface 211 is the same as the area of ​​the optical effective area of ​​the optical structure 100. The non-optical effective area of ​​the optical structure 100 of the present application is the area between the edge of the first lens 10 and the edge of the first surface 211, and the distance between the edge of the first lens 10 and the edge of the first surface 211 is very small, so the area of ​​the non-optical effective area is also very small. At this time, the overall volume of the optical structure 100 of the present application is small. Applying the optical structure 100 to a head-mounted display is conducive to reducing the volume of the head-mounted display and making it convenient for users to wear.

[0031] See also Figure 5 The present application also provides a method for manufacturing an optical structure, comprising the following steps: S1, forming a first initial lens, a second initial lens, a third initial lens and a fourth initial lens by injection molding.

[0032] S2, bonding the first initial lens and the second initial lens, and cutting the first initial lens and the second initial lens to form a first lens and a second lens.

[0033] S3, bonding the third initial lens and the fourth initial lens, and cutting the third initial lens and the fourth initial lens to form a third lens and a fourth lens.

[0034] S4, bonding the first lens and the third lens.

[0035] See also Figure 6 In step S1, in the step of forming the first initial lens 300 by injection molding, a plurality of positioning structures 301 are formed at intervals in a surface of the first initial lens 300, and a plurality of protrusions 11 are formed at intervals at the edge of the surface. The plurality of positioning structures 301 are used to locate the relative position between the first initial lens 300 and the second initial lens 400, and reduce the position deviation when the first initial lens 300 and the second initial lens 400 are bonded.

[0036] In step S2 , in the step of bonding the first initial lens 300 and the second initial lens 400 , the edge of the second initial lens 400 is aligned with the plurality of positioning structures 301 and then bonded to the first initial lens 300 and the second initial lens 400 so that the edge of the second initial lens 400 contacts the plurality of positioning structures 301 .

[0037] Please also read Figure 6 and Figure 7 In the step of cutting the first initial lens 300 and the second initial lens 400 to form the first lens 10 and the second lens 20, the plurality of positioning structures 301 on the first initial lens 300 are cut off so that the edge of the first lens 10 without the plurality of protrusions 11 coincides with the edge of the second lens 20. The second lens 20 includes a first surface 211 facing the first lens 10 and a second surface 212 opposite to the first surface 211, and the first surface 211 is curved toward the first lens 10.

[0038] In this step, by retaining the plurality of protrusions 11 on the first initial lens 300 and setting the thickness of each protrusion 11 to exceed the second surface 212 along the optical axis direction of the second lens 20, an air gap can be formed between the third lens and the second lens when the first lens and the third lens are adhered in step S4. In this embodiment, the distance between the outer edge of the surface of the first lens 10 on which the plurality of protrusions 11 are set and the edge of the first surface 211 of the second lens 20 can be 1 mm.

[0039] In step S3, the third lens includes a third surface, a fourth surface and a fifth surface connected in sequence. The third surface and the fourth surface are used to totally reflect the image light incident from the fifth surface and guide the image light to the first surface, and the first surface is used to reflect the image light to the fourth lens so that the image light is emitted from the fourth lens and finally received by the human eye.

[0040] In step S4, when the first lens and the third lens are bonded, the edge of the third surface of the third lens contacts the plurality of protrusions of the edge of the first lens, so that an air gap is formed between the third surface and the second surface. The refractive index of the third lens is greater than the refractive index of air, so that the image light incident on the side of the third surface away from the second surface can be totally reflected.

[0041] The manufacturing process of the manufacturing method of the above optical structure is simple, and the volume of the manufactured optical structure is light and thin. When the first initial lens and the second initial lens are cut to form the first lens and the second lens, the distance between the edge of the first lens and the edge of the second lens is small, so that the area of ​​the non-optical effective area of ​​the optical structure is small. At this time, most of the image light transmitted by the optical structure can be transmitted to the human eye. When the optical structure is applied to a head-mounted display, when the user uses the head-mounted display, most of the image light emitted by the display can be received by the human eye after passing through the optical structure, so the display screen seen by the user has a good display effect. The area of ​​the non-optical effective area of ​​the optical structure manufactured by the above method is small, which is conducive to reducing the overall volume of the optical structure, so that the volume of the manufactured optical structure is light and thin, thereby reducing the volume of the head-mounted display and reducing the burden on the user when wearing it.

[0042] The present application also provides a head mounted display. Figure 8 The head mounted display 1 provided in the embodiment of the present application includes a display 200 and an optical structure 100. The display 200 is used to emit image light LS, and the optical structure 100 is located on the optical path of the image light LS.

[0043] The display 200 is located on the side of the fifth surface 315 away from the fourth surface 314, and the fifth surface 315 is bent toward the display 200 to converge the image light LS. The fifth surface 315 allows the image light LS to be incident into the third lens 30, and then is incident to the fourth surface 314 after being totally reflected by the third surface 313. The fourth surface 314 is provided with an optical film 70, and the optical film 70 reflects part of the image light LS to the first surface 211 of the second lens 20, and the first surface 211 reflects the part of the image light LS, so that the part of the image light LS passes through the third lens 30 and the fourth lens 40 in sequence, and is emitted from the surface of the fourth lens 40 away from the third lens 30, and is finally received by the human eye.

[0044] In summary, the head mounted display 1 combines the display 200 with the optical structure 100, and the optical structure 100 causes the image light LS to be incident on the first surface 211 after undergoing an alternating reflection between the third surface 313 and the fourth surface 314, and then to be emitted from the fourth lens 40 after being reflected by the first surface 211. That is, the optical structure 100 causes the image light LS emitted from the display 200 to pass through the third lens 30, the second lens 20, the third lens 30, and the fourth lens 40 in sequence, and finally to be received by the human eye. It can be seen that the optical structure 100 reduces the volume of the head mounted display 1 by folding the optical path of the image light LS.

[0045] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present application and are not intended to be limiting of the present application. As long as they are within the spirit and scope of the present application, appropriate changes and modifications to the above embodiments are within the scope of protection claimed in the present application.

Claims

1. An optical structure, characterized in that: It comprises a first lens, a second lens, a third lens and a fourth lens, wherein the first lens, the second lens, the third lens and the fourth lens are arranged in sequence along the optical axis direction of the second lens; The second lens comprises a first surface facing the first lens and a second surface facing the third lens, and the first surface is curved toward the first lens; The third lens includes a third surface, a fourth surface and a fifth surface, an air gap is formed between the third surface and the second surface, the third surface is connected to the fourth surface and a non-zero angle is formed between the third surface and the fourth surface, the fifth surface is connected to the third surface and the fourth surface at the same time, the fourth lens is connected to the fourth surface, the third surface and the fourth surface are used to reflect the image light incident from the fifth surface and guide the image light to the first surface, and the first surface is used to reflect the image light to the fourth lens so that the image light is emitted from the fourth lens.

2. The optical structure according to claim 1, characterized in that A plurality of protrusions are arranged at intervals on the edge of the surface of the first lens close to the second lens, and the plurality of protrusions abut against the third surface to form the air gap.

3. The optical structure according to claim 1, characterized in that: The first lens covers the second lens.

4. The optical structure according to claim 1, characterized in that The fifth surface is also used to focus the image light.

5. The optical structure according to claim 1, characterized in that: It also includes an optical film located between the fourth surface and the fourth lens, which is used to reflect part of the image light and transmit part of the image light.

6. The optical structure according to claim 5, characterized in that The optical film is fixedly connected to the fourth surface and the fourth lens respectively through optical adhesive.

7. The optical structure according to claim 1, characterized in that: The ineffective optical area of ​​the first lens and the third lens are connected by structural adhesive.

8. The optical structure according to claim 7, characterized in that: The optical structure also includes a two-way air-permeable film, which is respectively connected to the second lens, the third lens and the structural adhesive. The two-way air-permeable film is used to keep the air pressure in the air gap consistent with the air pressure outside the optical structure.

9. A method for manufacturing an optical structure, characterized in that: The steps include: forming a first initial lens, a second initial lens, a third initial lens, and a fourth initial lens by injection molding; Bonding the first initial lens and the second initial lens, and cutting the first initial lens and the second initial lens to form a first lens and a second lens; the second lens comprises a first surface facing the first lens and a second surface opposite to the first surface, and the first surface is curved toward the first lens; Adhere the third initial lens and the fourth initial lens, and cut the third initial lens and the fourth initial lens to form a third lens and a fourth lens, wherein the third lens comprises a third surface, a fourth surface and a fifth surface, the third surface is connected to the fourth surface and a non-zero angle is formed between the third surface and the fourth surface, and the fifth surface is connected to the third surface and the fourth surface at the same time; The first lens and the third lens are bonded, an air gap is formed between the third surface and the second surface, the third surface and the fourth surface are used to totally reflect the image light incident from the fifth surface and guide the image light to the first surface, and the first surface is used to reflect the image light to the fourth lens so that the image light is emitted from the fourth lens.

10. The method for manufacturing an optical structure according to claim 9, characterized in that: In the step of forming the first initial lens by injection molding, a plurality of positioning structures are formed at intervals in a surface of the first initial lens, and a plurality of protrusions are formed at intervals on the edge of the surface of the first initial lens where the plurality of positioning structures are formed; In the step of bonding the first initial lens and the second initial lens, an edge of the second initial lens is in contact with the plurality of positioning structures.

11. The method for manufacturing an optical structure according to claim 10, characterized in that: In the step of cutting the first initial lens and the second initial lens to form the first lens and the second lens, a plurality of positioning structures on the first initial lens are cut off so that an edge of the first lens without the plurality of protrusions overlaps with an edge of the second lens.

12. A head mounted display, characterized in that: include: a display for emitting image light; as well as The optical structure according to any one of claims 1 to 8, located on the optical path of the image light, The display is located on a side of the fifth surface away from the fourth surface, and the fifth surface allows the image light to be incident into the third lens, pass through the third lens, the second lens, the third lens and the fourth lens in sequence, and be emitted from a surface of the fourth lens away from the third lens.

13. The head mounted display according to claim 12, wherein: The fifth surface is bent toward the display to focus the image light.

Images