WO2022083337A1

WO2022083337A1 - Optical film and optical imaging system

Info

Publication number: WO2022083337A1
Application number: PCT/CN2021/117170
Authority: WO
Inventors: 王霖; 唐晓峰; 张红秀; 胡飞; 李屹
Original assignee: 深圳光峰科技股份有限公司
Priority date: 2020-10-23
Filing date: 2021-09-08
Publication date: 2022-04-28
Also published as: CN114488527A

Abstract

An optical film (10) and an optical imaging system (100). The optical film (10) is attached to a windshield (20), and at least comprises a phase cancellation layer (13), a reflection layer (12) and a microstructure layer (11) that are stacked in sequence; the reflection layer (12) is used to reflect an image beam to form a first reflected beam; the phase cancellation layer (13) is used to amplify and/or deflect a second reflected beam, so as to guide the second reflected beam to a second exit direction; a normal vector of the microstructure layer (11) faces a first exit direction, and the microstructure layer (11) is used to guide the first reflected beam to the first exit direction; and the phase cancellation layer (13) is used to cancel the phase difference generated by the beam passing through the microstructure layer (11). The second reflected beam is formed by reflecting the image beam by the windshield (20), and the first exit direction is different from the second exit direction. In this way, a virtual image can be directly formed when the optical film (10) is attached to the surface of the windshield (20), and ghost images can further be eliminated.

Description

Optical film and optical imaging system

technical field

The present application relates to the field of display technology, and in particular, to an optical film and an optical imaging system.

Background technique

The Head Up Display (HUD) can transmit useful driving information to the windshield to generate a distant virtual image, which improves driving safety and reduces the risk of drivers leaving the road.

The existing HUD solution is to use the windshield as the final optical surface for imaging, and realize image magnification and imaging through a series of specular reflections; since the windshield itself does not have a good magnification and imaging function, the imaging group needs to pass a piece of Or two pieces of free-form surface reflectors, as shown in Figure 1, at the same time, it is also necessary to adjust the rotation angle of the free-form surface reflectors to match the height of different drivers; since multiple pieces of free-form surface reflectors need to occupy a certain space, and It needs to be installed under the windshield. The current practice is to implant the free-form surface mirror at the position of the dashboard under the windshield. However, using the windshield for imaging directly has many disadvantages, including ghosting on the front and rear surfaces, the need for Only multiple free-form surface reflectors can build the light path and occupy the space in the dashboard of the car. The principle of ghosting is shown in Figure 2. The light beam incident on the windshield will be reflected on the two surfaces of the windshield respectively. A distant virtual image 2 and a near virtual image 1 are respectively generated, and the overlapping of the two virtual images will affect the viewing effect.

SUMMARY OF THE INVENTION

The present application provides an optical film and an optical imaging system, which can directly form a virtual image when the optical film is attached to the surface of a windshield, and can also eliminate ghost images.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present application is to provide an optical film, which is attached to the windshield, at least including a phase cancellation layer, a reflective layer and a microstructure layer that are stacked in sequence; the reflective layer used to reflect the image beam to form the first reflected beam; the phase cancellation layer is used to amplify and/or deflect the second reflected beam to guide it to the second exit direction; the normal vector of the microstructure layer is directed to the first exit direction , the microstructure layer is used to guide the first reflected light beam to the first exit direction; the phase cancellation layer is used to cancel the phase difference generated by the light beam passing through the microstructure layer; wherein, the second reflection The light beam is formed by a windshield reflected image light beam, and the first outgoing direction and the second outgoing direction are different.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present application is to provide an optical imaging system, which includes an optical film and an image generator, and the image generator is used to generate an image light beam and inject the image light beam into the optical film, The optical film is used to reflect the image beam to the first exit direction to form a virtual image, and guide the image beam reflected by the windshield to the second exit direction, wherein the optical film is the above-mentioned optical film.

Through the above solution, the beneficial effects of the present application are: when the optical film is attached to the surface of the windshield, a virtual image can be formed through the reflective layer in the optical film, and the image beam can be imaged without an additional optical imaging device, Present to the human eye; at the same time, because the image beam reflected by the reflective layer is guided to the first outgoing direction, and the image beam reflected by the windshield is directed to the second outgoing direction, so that the image beam reflected by the windshield is formed. The virtual image formed by the reflective layer can be distinguished from the virtual image formed by the image beam reflected by the reflective layer, eliminating the ghosting caused by the partial overlapping of the two virtual images, and facilitating the observation of the virtual image.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present application more clearly, the following briefly introduces the drawings that are used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort. in:

Fig. 1 is the light path schematic diagram of realizing HUD scheme in the prior art;

Fig. 2 is the schematic diagram that realizes the existence of image ghosting in the HUD scheme in the prior art;

3 is a schematic diagram of a layer structure of an optical film in an embodiment provided by the present application;

Fig. 4 is the light path schematic diagram of imaging in the embodiment shown in Fig. 3;

5 is a schematic diagram of the layer structure of the optical film in another embodiment provided by the present application;

Fig. 6 (a) is the schematic diagram that the microstructure unit is arranged according to quadrilateral in the embodiment shown in Fig. 5;

Fig. 6 (b) is the schematic diagram that the microstructure unit is arranged according to hexagon in the embodiment shown in Fig. 5;

FIG. 7 is a schematic diagram of the optical path of imaging in the embodiment shown in FIG. 5;

8 is a schematic diagram of a curve between reflectivity and transmittance in the embodiment shown in FIG. 5;

Fig. 9 is another optical path schematic diagram of imaging in the embodiment shown in Fig. 5;

FIG. 10 is a schematic structural diagram of an embodiment of an optical imaging system provided by the present application.

Detailed ways

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, but not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

The present application provides an optical film imaging device, which can be attached to the inside of the windshield of a car to realize HUD display, and does not need to be equipped with the device at other positions of the car, which saves the space occupied by the realization of the HUD and simplifies the installation process; , the optical thin film imaging device provided by the present application can overcome the problem of image ghosting when the HUD is implemented in the prior art, and improve the user's visual experience.

Please refer to FIG. 3 and FIG. 4 , FIG. 3 is a schematic diagram of a layer structure of an optical film in an embodiment provided by the present application, and FIG. 4 is a schematic diagram of an imaging optical path in the embodiment shown in FIG. 3 .

The optical film 10 includes a microstructure layer 11 and a reflective layer 12. The optical film 10 is attached to the windshield 20 through the microstructure layer 11. As shown in FIG. 4, the image generator 30 is used to generate an image beam to form a virtual image.

In order to ensure that the light beam passing through the microstructure layer 11 is not affected by the shape of the microstructure layer 11, a phase cancellation layer 13 can be fabricated, and the phase cancellation layer 13 can cancel the phase difference generated by the light beam passing through the microstructure layer 11. Specifically, The refractive indices of the phase cancellation layer 13 and the microstructure layer 11 are the same, and the phase cancellation layer 13 and the microstructure layer 11 are rotationally symmetric structures to cancel the phase difference generated by the light beam passing through the microstructure layer 11. The microstructure layer 11 , the reflection layer 12 and the phase cancellation layer 13 are stacked.

The image beam emitted from the image generator 30 is incident on the phase cancellation layer 13 in the optical film 10 , passes through the phase cancellation layer 13 and then reaches the reflective layer 12 .

The reflective layer 12 is used to reflect the image beam emitted from the phase cancellation layer 13 to form a first reflected beam. The first reflected beam passes through the phase cancellation layer 13 and then exits along the first exit direction. The opposite direction of the outgoing direction forms a first virtual image; the microstructure layer 11 can guide the first reflected light beam to the first outgoing direction, and the normal vector of the microstructure layer 11 faces the first outgoing direction.

Further, in order to ensure that the optical film 10 does not affect the light transmittance of the windshield glass 20 when the optical film 10 is attached to the windshield glass 20 , the reflective layer 12 is a semi-transparent and semi-reflective metal film or a dielectric film. Therefore, the reflective layer 12 can transmit part of the image light, and part of the image light can be incident on the windshield 20 through the microstructure layer 11 , and the part of the image light is reflected by the windshield 20 to form a second reflected light beam, and the phase cancellation layer 13 can The second reflected light beam is amplified and/or deflected to be guided to the second exit direction; specifically, the second reflected light beam passes through the microstructure layer 11 , the reflection layer 12 and the phase cancellation layer 13 in sequence, and then exits the optical film 10 , the outgoing second reflected light beam forms a second virtual image in the opposite direction of the second outgoing direction, and the first outgoing direction is different from the second outgoing direction, so that the first virtual image and the second virtual image can be distinguished.

Since the windshield glass 20 has a certain thickness, part of the image light transmitted to the windshield glass 20 through the reflective layer 12 is reflected by the two surfaces of the windshield glass 20 to form two overlapping second virtual images, as shown in FIG. 4 . Show. In order to prevent the second virtual image and the first virtual image from overlapping each other and causing ghost images, the optical film 10 can be designed so that the angle at which the optical film 10 reflects the image beam and the angle at which the windshield 20 reflects the image beam are distinguished; The second virtual image formed by the second reflected light beam cannot enter the sight range of people.

The phase cancellation layer 13 in the optical film 10 provided in this embodiment can cancel the phase difference caused by the microstructure layer 11 . When the optical film 10 is attached to the surface of the windshield 20 , a virtual image is directly formed, and no additional optical imaging device is required. The image beam generated by the image generator 30 can be turned into an enlarged virtual image, which is presented on the outside of the windshield 20, and the virtual image can overlap with the real scene of the road, so as to better meet the user's needs for road navigation and information prompts; And since the angle at which the image beam is reflected by the optical film 10 and the angle at which the image beam is reflected by the windshield 20 can be distinguished, the human eye can distinguish the first virtual image generated by the first reflected beam from the second virtual image area generated by the second reflected beam. , so as to eliminate ghost images and facilitate the observation of virtual images.

Please refer to FIG. 4 and FIG. 5. FIG. 5 is a schematic diagram of the layer structure of the optical film in another embodiment provided by the present application. The difference from the previous embodiment is that the optical film 10 in this embodiment further includes a first substrate. 14 and the second substrate 15 , the first substrate 14 is arranged on the side of the microstructure layer 11 away from the reflective layer 12 , and the second substrate 15 is arranged on the side of the phase cancellation layer 13 away from the reflective layer 12 .

The materials of the first substrate 14 and the second substrate 15 can be hard substrates such as glass or acrylic, or PET (Polyethylene Terephthalate, polyethylene terephthalate) or PC (Polycarbonate, polycarbonate) ) and other soft and flexible substrates; specifically, a curable resin material can be coated on the surface of the substrate, such as acrylic or polyurethane resins cured by UV (ultraviolet, ultraviolet) or heat, and then passed through the master mold. The base material (including the first base material 14 and the second base material 15 ) is fabricated by the imprinting process.

In order to distinguish the angle at which the optical film 10 reflects the image beam and the angle at which the windshield 20 reflects the image beam, the microstructure layer 11 and the phase cancellation layer 13 may be designed.

Further, the microstructure layer 11 includes a plurality of forward microstructure units, the phase cancellation layer 13 includes a plurality of reverse microstructure units, and a plurality of forward microstructure units and/or a plurality of reverse microstructure units are arranged in an array ( That is, arranged in the form of an array), the reverse microstructure unit and the forward microstructure unit are complementary structures to offset the phase difference brought by the forward microstructure unit; the reflective layer 12 at least partially covers the forward microstructure unit and the reverse The surface of the microstructured unit.

The microstructure unit (including the forward microstructure unit and the reverse microstructure unit) has an optical surface, the optical surface is a plane, and each microstructure unit has a normal vector, the normal vector and the optical surface of the microstructure unit Vertical, set the normal vector to face the first outgoing direction, by adjusting the direction of the normal vector, the virtual image formed by the image beam reflected by the reflective layer 12 can be distinguished from the virtual image formed by the image beam reflected by the windshield 20, Therefore, it is necessary to calculate the normal vector of the microstructure unit, and specifically, the calculation can be performed according to the directions of the incident image beam and the outgoing image beam.

Further, the image generator 30 includes a plurality of light-emitting units. In order to distinguish the virtual image, the reflection angle of the optical film 10 and the reflection angle of the wind glass 20 can be set first, and then a preset number of light-emitting units are selected in the image generator 30 as With reference to the light-emitting unit, under the condition that the thickness and material of each layer of the optical film 10 remain unchanged, the position of the virtual image point formed by each reference light-emitting unit is simulated and calculated, and by adjusting the inclination angle of the optical surface of each microstructure unit, Finally, the normal vector of each optical surface that satisfies the condition of no ghosting can be obtained.

In a specific embodiment, a preset number of reference light-emitting units may be uniformly selected to ensure that the image generator 30 has a relatively consistent imaging effect; for example, as shown in FIG. For the reference light-emitting units P1 and P2, the normal vector of each micro-structure unit can be obtained through simulation calculation without ghosting. The optical film 10 attached to the windshield 20 can affect the image beam generated by the image generator 30. Reflection is performed to form a virtual image, the reference light-emitting unit P1 corresponds to the virtual image point I1, and the reference light-emitting unit P2 corresponds to the virtual image point I2.

When making the microstructure unit, the engraving machine can be used for machining or mask exposure process to make the master board of the microstructure unit; after the master board is made, it can be stamped, injection molded or roll-to-roll molding process, etc. Mass production in multiple ways.

The microstructure unit may have a polygonal boundary. Specifically, the cross-sectional shape of the positive microstructure unit may be a triangle, a quadrilateral or a hexagon, etc. As shown in Figure 6(a), the cross-section of the microstructure unit is a quadrilateral. The normal vector of the structural unit is perpendicular to the quadrilateral optical surface, or as shown in Figure 6(b), the cross-section of the micro-structural unit is hexagonal, and the normal vector of the micro-structural unit is perpendicular to the hexagonal optical surface.

It can be understood that the cross-sectional shape of the microstructure unit does not affect the effect of optical imaging, and the shape of the microstructure unit can be set as required.

Since the image beam incident on the optical surface needs to be reflected by geometric optics as much as possible to reduce the diffraction effect caused by the finite edge, the minimum envelope size of the microstructure unit needs to be more than 10 times larger than the light wave size of visible light, and the light wave size is 1000nm. For example, the minimum envelope diameter of the microstructure unit is greater than 10 μm; and considering that the larger the size of the microstructure unit, the more serious the pixelation of the rendered image, and the approximation of the microstructure unit and the curved surface will be reduced, resulting in the windshield and the windshield. The degree of fit of 20 decreases, which affects the visual effect of imaging. Therefore, the minimum envelope diameter of the microstructure unit can be set to be less than 500 μm, that is, the envelope diameter of the microstructure unit is 10 to 500 μm, where the diameter of the minimum envelope can refer to is the diameter of the circumcircle of a microstructure unit. It should be noted that the restriction on the minimum envelope diameter is not a fixed range, that is, the minimum envelope diameter can also be less than 10 μm when the above conditions are met (reducing the edge diffraction effect, and having a high degree of fit with the windshield 20 ). Or more than 500μm.

After the microstructure layer 11 is fabricated by using the motherboard, a reflective layer 12 can be fabricated on the optical surface of the microstructure layer 11, the reflective layer 12 covers the optical surface of the forward microstructure unit, and the reflective layer 12 can be a metal film or a dielectric film , in order to make the reflective layer 12 transmit the image beam to form a virtual image while satisfying the reflected image beam, the reflectivity of the reflective layer 12 is 10% to 30%, and the transmittance of the reflective layer 12 is 40% to 80%; specifically , a semi-transmissive and semi-reflective metal film or dielectric film can be plated on the surface of the microstructure layer 11. According to the curve between the reflectivity and transmittance of the metal film shown in FIG. 8, it can be known that when the reflectivity is controlled at 10% A better transmittance can be obtained in the range of ~30%.

In other embodiments, in order to facilitate the human eye to observe multiple pieces of information, the optical film 10 can be designed to display virtual images at different positions, some virtual images are imaged at a closer position, and some virtual images are imaged at a farther position. Position, for example, the information of low-speed driving can be displayed in a relatively close position, and the information of high-speed driving can be displayed in a far position; When the image beam is incident on the optical film 10, virtual images at different distances are formed. For example, as shown in FIG. 9, the optical film 10 attached to the windshield 20 reflects the image beam generated by the image generator 30, and the image beams are reflected at different distances. A virtual image is formed, the reference light-emitting unit P1 on the image generator 30 corresponds to the virtual image point I1, the reference light-emitting unit P2 on the image generator 30 corresponds to the virtual image point I2, and the reference light-emitting unit P3 on the image generator 30 corresponds to the virtual image point I3 , the virtual image point I1 and the virtual image point I2 are farther from the observer, the virtual image point I3 is closer to the observer, and the size of the virtual image corresponding to the virtual image point I1 and the virtual image point I2 is greater than the virtual image point I3 The size of the corresponding virtual image.

The optical film 10 provided in this embodiment is formed by laminating positive microstructural units and negative microstructural units. The negative microstructural units and the positive microstructural units have the same structure and opposite orientation, forming an optical film 10 with a uniform thickness. Controlling the direction of the normal vector of each microstructure unit can realize the reflection of the image beam at a specific angle to eliminate ghosting, and the optical film 10 can be attached to the surface of the windshield for direct imaging without additional optical The imaging device can turn the image displayed by the image generator 30 into an enlarged virtual image and present it to the human eye.

Please refer to FIG. 10. FIG. 10 is a schematic structural diagram of an embodiment of an optical imaging system provided by the present application. The optical imaging system 100 includes an optical film 10 and an image generator 30. The image generator 30 is used to generate an image beam and convert the image beam to the Entering the optical film 10, the optical film 10 is used to reflect the image beam to the first exit direction to form a first virtual image in the opposite direction to the first exit direction, and transmit the image beam reflected by the windshield to the second exit direction to form a second virtual image in the opposite direction to the second output direction, wherein the optical film 10 is the optical film in the above-mentioned embodiment, and the first output direction is different from the second output direction, so that the first virtual image and the second output direction are different. Virtual images can be distinguished.

The optical film 10 includes at least one area film, and the virtual images formed by the image beams reflected by each area film are located at different distances and do not overlap each other, wherein the farther the virtual image is, the larger the virtual image is.

Further, the optical imaging system 100 is a HUD system. In the HUD system, the content of the image generator 30 can be imaged to a virtual image position at the same distance, and part of the content is also displayed at a long distance, and part of the content is displayed at a closer distance. 9, a part of the image light beams generated by the reference light-emitting unit in the image generator 30 is used to form a close-range virtual image, while another part of the image light beam generated by the reference light-emitting unit is used to form a long-distance virtual image, in order to observe Conveniently, distant virtual images are larger in size and have higher magnification than near virtual images.

When the optical film 10 in the optical imaging system 100 provided in this embodiment is attached to the surface of the windshield as a HUD screen, a virtual image can be directly formed, and an image generated by the image generator 30 can be generated without an additional optical imaging device. The light beam is imaged and presented to the human eye; the first virtual image and the second virtual image generated at the same time do not overlap each other, so that the human eye can distinguish the virtual image, so ghosting can be eliminated; and the system has a simple structure and does not need to occupy additional interior space , which increases the convenience of installation and operation, and can reduce the cost of the system.

The above are only the embodiments of the present application, and are not intended to limit the scope of the patent of the present application. Any equivalent structure or equivalent process transformation made by using the contents of the description and drawings of the present application, or directly or indirectly applied in other related technical fields, All are similarly included in the scope of patent protection of the present application.

Claims

An optical film, characterized in that the optical film is attached to a windshield, and at least comprises a phase cancellation layer, a reflection layer and a microstructure layer that are stacked in sequence;

The reflective layer is used to reflect the image light beam to form the first reflected light beam; the phase cancellation layer is used to amplify and/or deflect the second reflected light beam to guide it to the second output direction; the method of the microstructure layer The vector is directed towards the first outgoing direction, and the microstructure layer is used to guide the first reflected light beam to the first outgoing direction; the phase cancellation layer is used to cancel the phase generated by the light beam passing through the microstructure layer difference;

Wherein, the second reflected light beam is formed by reflecting the image light beam from the windshield, and the first outgoing direction and the second outgoing direction are different.
The optical film of claim 1, wherein

The phase cancellation layer and the microstructure layer have the same refractive index, and the phase cancellation layer and the microstructure layer are rotationally symmetric structures.
The optical film according to claim 2, wherein

The phase cancellation layer includes a plurality of forward microstructure units, the microstructure layer includes a plurality of reverse microstructure units, and the forward microstructure units and the reverse microstructure units are complementary structures.
The optical film according to claim 3, wherein

The envelope diameter of the forward microstructure unit and the reverse microstructure unit is 10-500 μm, and the plurality of forward microstructure units/the plurality of reverse microstructure units are arranged in the form of an array.
The optical film according to claim 3, wherein

The reflective layer at least partially covers the surfaces of the forward microstructure unit and the reverse microstructure unit, and the cross-sectional shapes of the forward microstructure unit and the reverse microstructure unit are triangles, quadrilaterals or hexagons shape.
The optical film of claim 1, wherein

The optical film further includes a first base material and a second base material, the first base material is disposed on the side of the phase cancellation layer away from the reflection layer, and the second base material is disposed on the microstructure layer away from the side of the reflective layer.
The optical film according to claim 6, wherein

The materials of the first substrate and the second substrate include glass, acrylic, polyethylene terephthalate or polycarbonate.
The optical film of claim 1, wherein

The reflection layer is a metal film or a dielectric film, the reflection rate of the reflection layer is 10%-30%, and the transmittance of the reflection layer is 40%-80%.
An optical imaging system, characterized in that it comprises an optical film and an image generator, the image generator is used to generate an image beam, and the image beam is injected into the optical film, and the optical film is used to reflect the The image beam is directed to the first exit direction to form a virtual image, and the image beam reflected by the windshield is guided to the second exit direction, wherein the optical film is the optical film described in any one of claims 1-8.
The optical imaging system according to claim 9, wherein,

The optical film includes at least one area film, and the virtual images formed by the image light beams reflected by each of the area films are located at different distances and do not overlap each other, wherein the farther the virtual image is, the larger the virtual image is.