Exit pupil expansion optical display device and composite structure
By using a collimating lens group, a planar reflective layer and a semi-reflective semi-transparent layer in the vehicle head-up display system, the pupil-out expansion optical display device is solved, and the production problem of small volume and low cost in the prior art is difficult to achieve, and the expansion of large field of view and large pupil size is achieved, while reducing processing difficulty and process costs.
Patent Information
- Application Number
- CN202411777158.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-05
- Publication Date
- 2025-03-18
AI Technical Summary
While ensuring large field of view and large pupil size, existing vehicle-mounted head-up display systems are difficult to achieve small volume and low cost production, and are difficult to process and have high process costs.
The pupil extension optical display device is adopted that includes a collimating lens group, a plane reflective layer and a semi-inverted semi-transmissive layer. By controlling the reflection transmission ratio of the semi-inverted semi-transmissive layer, multiple internal reflections and partial exits of the collimated light beam are realized, and the pupil extension function is realized, while controlling the energy uniformity of the outgoing light beam.
It realizes the expansion of the field angle and the size of the pupil output under a small volume, while reducing the processing difficulty and process cost. It overcomes the problems of mutual constraints between the field angle, the size of the pupil output and the volume of the optical system in the prior art, and has the advantages of high imaging quality.
Smart Images
Figure CN119644581A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a vehicle-mounted head-up display system, and in particular to an exit pupil expansion optical display device and a composite structure. Background Art
[0002] The in-vehicle head-up display system can project vehicle driving information directly onto the front windshield, allowing the driver to obtain driving data, lane conditions and other information without having to look down at the dashboard, thereby improving driving safety and comfort.
[0003] In order to achieve a large field of view and a large exit pupil, traditional head-up display systems need to use large curved mirrors to reflect images. However, large curved mirrors are large in size and difficult to process. In addition, the head-up display system needs to be installed near the car dashboard, where the space is small, limiting the overall size of the head-up display system. This makes it very difficult to further increase the field of view of the head-up display system while ensuring the exit pupil size.
[0004] At present, the mainstream pupil expansion method of the vehicle head-up display system adopts a flat waveguide structure, using gratings, prisms, metasurfaces, microstructures and other devices to couple the target collimated light beam into the flat waveguide for total reflection, and then use gratings, embedded reflective film arrays, metasurfaces, microstructures and other devices in a certain area of the flat waveguide to couple part of the totally reflected light out of the waveguide. By controlling the coupling output efficiency, the collimated light is partially coupled out of the waveguide and part continues to propagate through total reflection, and finally the pupil replication and expansion of the collimated light beam are achieved. Although the flat waveguide structure pupil expansion method is small in size, the gratings, embedded reflective film arrays, metasurfaces, microstructures and other devices used are too small in size, difficult to process, and have high process costs, which is not conducive to large-scale production applications. Summary of the invention
[0005] Purpose of the invention: The first purpose of the present invention is to provide an exit pupil expansion optical display device with simple structure, low cost and easy processing under the premise of ensuring a large field of view, a large exit pupil size and a small volume; the second purpose of the present invention is to provide an exit pupil expansion optical display composite structure based on the exit pupil expansion optical display device.
[0006] Technical solution: An exit pupil expansion optical display device of the present invention comprises a collimating lens group, and a plane reflection layer and a semi-reflective and semi-transparent layer arranged in parallel; the collimating lens group is used to collimate the light beam emitted by the display screen into a parallel light beam, the collimated parallel light beam is incident through an incident window reserved on the semi-reflective and semi-transparent layer, and is reflected by the plane reflection layer to form a reflected light beam, and an acute angle θ is formed between the collimated parallel light beam and the normal of the plane reflection layer; the reflected light beam is divided into two parts according to the reflection-transmission ratio of the reflection-transmission position of the semi-reflective and semi-transparent layer, one part is reflected by the semi-reflective and semi-transparent layer and continues to propagate between the plane reflection layer and the semi-reflective and semi-transparent layer, and the other part is transmitted through the semi-reflective and semi-transparent layer to form an exit light beam; by controlling the reflection-transmission ratio of each reflection-transmission position of the semi-reflective and semi-transparent layer, multiple internal reflections and partial exit of the collimated parallel light beam in the exit pupil expansion optical display device are realized, thereby realizing the exit pupil expansion function and controlling the energy uniformity of the exit light beam at the same time.
[0007] Furthermore, the acute angle θ is 5° to 80°.
[0008] Furthermore, the distance that the collimated parallel light beam propagates twice in the same layer is d=2*h*tan(θ), where h is the relative distance between the plane reflective layer and the semi-reflective and semi-transmissive layer, and h is set to be less than a constant value to ensure that the propagation distance d of the light beam incident at the maximum angle θ is less than the exit pupil of the collimating lens group.
[0009] Furthermore, the plane reflection layer and the semi-reflective and semi-transmissive layer are optically transparent, and the filling material between the two layers is vacuum, or air, or an inert gas for protection, or a transparent medium for support.
[0010] Furthermore, the plane reflection layer is a metal film reflection mirror or a dielectric film reflection mirror, and its base material is optical glass, optical plastic or metal material.
[0011] Furthermore, the planar reflective layer is a metal coating or a polished surface of a metal substrate.
[0012] Furthermore, the semi-reflective and semi-transmissive layer substrate is optical glass or optical plastic, coated with a semi-transmissive and semi-reflective film; the reflection and transmission ratio of each reflection and transmission position of the semi-reflective and semi-transmissive layer is controlled by changing the thickness and number of layers of the dielectric film layer or the metal film layer.
[0013] Furthermore, the collimating lens group is composed of a plurality of lenses, the lens material is optical glass or optical plastic, and the distortion in the whole field of view is less than 1%.
[0014] A pupil expansion optical display composite structure of the present invention includes two of the above-mentioned pupil expansion optical display devices. One pupil expansion optical display device is used to achieve pupil expansion of a collimated parallel light beam in one direction, and the other pupil expansion optical display device is used to achieve pupil expansion in a direction perpendicular to the one direction, thereby realizing a two-dimensional pupil expansion function.
[0015] Optionally, a pupil expansion optical display composite structure of the present invention includes an exit pupil expansion optical display device as described above, and an exit pupil expansion optical display device is used to achieve pupil expansion of a collimated parallel light beam in one direction, and is combined with a semi-reflective and semi-transparent film array, or a one-dimensional exit pupil expansion grating, or a one-dimensional exit pupil expansion metasurface to achieve pupil expansion in a direction perpendicular to the one direction, thereby realizing a two-dimensional exit pupil expansion function.
[0016] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:
[0017] The pupil expansion optical display device provided by the present invention adopts a plane reflection layer and a semi-reflective and semi-transparent layer. Compared with the pupil expansion method of a flat waveguide structure, the structure and principle are simpler, the preparation process of the constituent components is mature, the processing difficulty is low, and the process cost is low. In addition, the present invention can maintain a small device volume while expanding the field of view angle and the exit pupil size of the device, overcoming the disadvantage that the field of view angle size, exit pupil size and optical system volume and other indicators in the optical system are mutually restricted. The present invention can conveniently and accurately control and amplify the projected projection light, and has the advantage of high imaging quality. The present invention can be widely used in head-up display systems of vehicles such as automobiles and airplanes and other display systems that require pupil expansion. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 is a schematic structural diagram of an exit pupil expansion optical display device provided by an embodiment of the present invention;
[0019] Figure 2 is a top view of a two-dimensional exit pupil expansion optical display composite structure in an embodiment of the present invention;
[0020] Figure 3 It is a top view of another two-dimensional exit pupil expansion optical display composite structure in an embodiment of the present invention. DETAILED DESCRIPTION
[0021] The present invention will be further described below in conjunction with the accompanying drawings.
[0022] Attached Figures 1 to 3 The reference numerals in the figures are as follows:
[0023] 1. Display screen; 2. Collimating lens group; 3. Plane reflective layer; 4. Semi-reflective and semi-transparent layer; 5. Outgoing light beam; 6. Human eye pupil.
[0024] like Figure 1 As shown, an embodiment of the present invention provides an exit pupil expansion optical display device, comprising a collimating lens group 2, and a planar reflective layer 3 and a semi-reflective and semi-transmissive layer 4 arranged in parallel.
[0025] The display screen 1 is arranged on the focal plane of the collimating lens group 2. The collimating lens group 2 is used to collimate the light beam emitted by the display screen 1 into a parallel light beam and emit it. The plane reflective layer 3 and the semi-reflective and semi-transmissive layer 4 are arranged on the exit light path of the collimating lens group 2. The collimated parallel light beam is incident through the incident window reserved on the semi-reflective and semi-transmissive layer 4, and is reflected by the plane reflective layer 3 to form a reflected light beam. An acute angle θ is formed between the collimated parallel light beam and the normal line of the plane reflective layer 3, and the acute angle θ is 5° to 80°.
[0026] The reflected light beam is divided into two parts according to the reflection-transmission ratio of the reflection-transmission position of the semi-reflective and semi-transmissive layer 4. One part is reflected by the semi-reflective and semi-transmissive layer 4 and continues to propagate between the plane reflection layer 3 and the semi-reflective and semi-transmissive layer 4, and the other part is transmitted through the semi-reflective and semi-transmissive layer 4 to form an outgoing light beam 5.
[0027] By controlling the reflection-transmission ratio of each reflection-transmission position of the semi-reflective and semi-transmissive layer 4, multiple internal reflections and partial emission of the collimated parallel light beam in the pupil expansion optical display device can be achieved, the pupil expansion of the light beam can be achieved and emitted to the pupil 6 of the human eye, while achieving uniform energy of the emitted light beam 5.
[0028] The collimating lens group 2 is composed of multiple lenses, the lens material is optical glass or optical plastic, and the distortion in the whole field of view is less than 1%.
[0029] The plane reflective layer 3 is a metal film reflector or a dielectric film reflector, and its substrate is optical glass, optical plastic or metal material, and its reflectivity reaches more than 95% in the visible light wavelength range of 400nm to 700nm. The plane reflective layer 3 is preferably a front surface reflector.
[0030] The plane reflective layer 3 can also be selected as a metal plating layer or a polished surface of a metal substrate. The metal substrate can be integrated with the structural parts of the device to provide higher mechanical strength; the metal substrate can also be used as a component of the device to achieve the heat dissipation function of the display screen.
[0031] The substrate of the semi-reflective and semi-transmissive layer 4 is optical glass or optical plastic, coated with a semi-transmissive and semi-reflective film; the reflection and transmission ratio of each reflection and transmission position of the semi-reflective and semi-transmissive layer 4 is controlled by changing the thickness and number of dielectric film layers or metal film layers to achieve local changes at different positions. In this embodiment, the lower surface of the semi-reflective and semi-transmissive layer 4 is coated with dielectric film layers or metal film layers with different reflectivities, and its reflectivity to visible light is 50% to 95% according to different plane positions.
[0032] The parallel error between the plane reflective layer 3 and the semi-reflective and semi-transmissive layer 4 is less than 0.5 arc minutes, the surface optical flatness error is less than 1 um, and the relative distance h between the plane reflective layer 3 and the semi-reflective and semi-transmissive layer 4 is 0.5 cm to 8 cm. The plane reflective layer 3 and the semi-reflective and semi-transmissive layer 4 are optically transparent, and the filling material between the two layers is vacuum, or air, or an inert gas for protection, or a transparent medium for support, such as optical glass or optical plastic.
[0033] The parallel light beam incident at an angle of θ is reflected and propagated between the plane reflective layer 3 and the semi-reflective and semi-transmissive layer 4. The distance that the collimated parallel light beam propagates twice in the same layer is d=2*h*tan(θ), and h is set to be less than a constant value to ensure that the propagation spacing d of the light beam incident at the maximum angle θ is less than the exit pupil of the collimating lens group 2, thereby ensuring the continuity of the pupil after the exit pupil expansion device expands the pupil.
[0034] The embodiment of the present invention further provides a pupil expansion optical display composite structure, comprising two pupil expansion optical display devices according to the embodiment of the present invention, one pupil expansion optical display device is used to realize pupil expansion of a collimated parallel light beam in one direction, and another pupil expansion optical display device is used to realize pupil expansion in a direction perpendicular to the one direction, thereby realizing a two-dimensional pupil expansion function. The sizes of the two pupil expansion optical display devices, the sizes of the incident windows, and the spatial angle relationship are adjusted accordingly according to the propagation direction of the light beam to realize input and output coupling of the two-dimensional pupil expansion light beam. Figure 2 and Figure 3 Two two-dimensional exit pupil expansion optical display composite structures are given as examples.
[0035] In some embodiments, the other pupil expansion optical display device mentioned above can be replaced by a semi-reflective and semi-transparent film array, or a one-dimensional pupil expansion grating, or a one-dimensional pupil expansion metasurface, which can also achieve the two-dimensional pupil expansion function.
[0036] In summary, the pupil expansion optical display device provided by the present invention can realize the replication and expansion of the incident collimated light beam pupil in the vertical or horizontal direction, and equivalently replicate and enlarge the pupil of the exit light path, and emit it to the pupil of the human eye. The pupil expansion optical display composite structure provided by the present invention can realize two-dimensional exit pupil expansion.
Claims
1. An exit pupil expansion optical display device, characterized in that: The invention comprises a collimating lens group (2), and a plane reflection layer (3) and a semi-reflective and semi-transmissive layer (4) arranged in parallel; the collimating lens group (2) is used to collimate the light beam emitted by the display screen (1) into a parallel light beam, the collimated parallel light beam is incident through an incident window reserved on the semi-reflective and semi-transmissive layer (4), and is reflected by the plane reflection layer (3) to form a reflected light beam, and an acute angle θ is formed between the collimated parallel light beam and the normal of the plane reflection layer (3); the reflected light beam is divided into two parts according to the reflection-transmission ratio of the reflection-transmission position of the semi-reflective and semi-transmissive layer (4), one part is reflected by the semi-reflective and semi-transmissive layer (4) and continues to propagate between the plane reflection layer (3) and the semi-reflective and semi-transmissive layer (4), and the other part is transmitted through the semi-reflective and semi-transmissive layer (4) to form an exit light beam (5); by controlling the reflection-transmission ratio of each reflection-transmission position of the semi-reflective and semi-transmissive layer (4), multiple internal reflections and partial exit of the collimated parallel light beam in the exit pupil expansion optical display device are realized, the exit pupil expansion function is realized, and the energy uniformity of the exit light beam (5) is controlled at the same time.
2. The pupil expansion optical display device according to claim 1, characterized in that: The acute angle θ is 5° to 80°.
3. The exit pupil expansion optical display device according to claim 2, characterized in that: The distance that the collimated parallel light beam propagates twice in the same layer is d=2*h*tan(θ), wherein h is the relative distance between the plane reflection layer (3) and the semi-reflective and semi-transmissive layer (4), and h is set to be less than a fixed value to ensure that the propagation distance d of the light beam incident at the maximum angle θ is less than the exit pupil of the collimating lens group (2).
4. The pupil expansion optical display device according to claim 1, characterized in that: The plane reflection layer (3) and the semi-reflective and semi-transmissive layer (4) are optically transparent, and the filling material between the two layers is vacuum, or air, or an inert gas that plays a protective role, or a transparent medium that plays a supporting role.
5. The pupil expansion optical display device according to claim 1, characterized in that: The plane reflection layer (3) is a metal film reflection mirror or a dielectric film reflection mirror, and its base material is optical glass, optical plastic or metal material.
6. The pupil expansion optical display device according to claim 1, characterized in that: The plane reflection layer (3) is a metal coating or a polished surface of a metal substrate.
7. The pupil expansion optical display device according to claim 1, characterized in that: The substrate of the semi-reflective and semi-transmissive layer (4) is optical glass or optical plastic, coated with a semi-transmissive and semi-reflective film; the reflection and transmission ratio of each reflection and transmission position of the semi-reflective and semi-transmissive layer (4) is controlled by changing the thickness and number of dielectric film layers or metal film layers.
8. The pupil expansion optical display device according to claim 1, characterized in that: The collimating lens group (2) is composed of a plurality of lenses, the lens material is optical glass or optical plastic, and the distortion in the whole field of view is less than 1%.
9. An exit pupil expansion optical display composite structure, characterized in that: The method comprises two pupil expansion optical display devices according to any one of claims 1 to 8, wherein one pupil expansion optical display device is used to realize pupil expansion of a collimated parallel light beam in one direction, and another pupil expansion optical display device is used to realize pupil expansion in a direction perpendicular to the one direction, thereby realizing a two-dimensional pupil expansion function.
10. An exit pupil expansion optical display composite structure, characterized in that: The invention comprises an exit pupil expansion optical display device as claimed in any one of claims 1 to 8, wherein an exit pupil expansion optical display device is used to realize the exit pupil expansion of a collimated parallel light beam in one direction, and a semi-reflective and semi-transparent film array, or a one-dimensional exit pupil expansion grating, or a one-dimensional exit pupil expansion metasurface is used to realize the exit pupil expansion in a direction perpendicular to the one direction, thereby realizing a two-dimensional exit pupil expansion function.