TW201947279A - Light synthesizer structure of virtual image display for allowing an automobile driver to view the front scenery through the light scenery and to view the front virtual image by reflection - Google Patents

Abstract

Provided is a light synthesizer structure of a virtual image display, which is composed of a light-transmission substrate and a compensation sheet. Each of the substrate and the compensation sheet has a thick side and a thin side, and is formed with a spherical curvature on the surface thereof. When the thick side of the substrate is mated to the thin side of the compensation sheet, and the thin side of the substrate is mated to the thick side of the compensation sheet, a convex surface of the substrate is placed on a concave surface of the compensation sheet and therefore a gap is defined between the substrate and the compensation sheet so as to form a light synthesizer structure. When the light of an image is projected by the image projection system of the virtual image display according to the invention, there is a reflection formed on the spherical convex surface of the substrate and the concave surface of the compensation sheet, that is, on the joint surfaces of the substrate and the compensation sheet respectively adjacent to the gap. Through the design of the reflection angle of the optical system, the light is emitted into the eye box of the user, and a virtual image is formed at the other end through the curvature magnification effect of the joint surface between the substrate and the compensation sheet.

Description

   Light synthesizer structure of virtual image display   

The invention relates to a light synthesizer used in a virtual image system application, such as a head up display (HUD), an augmented reality (AR), and other systems.

Virtual image system applications such as: Head Up Display (hereinafter referred to as HUD), Augmented Reality (AR) and other virtual image systems have gradually become widely used in recent years; optical synthesizers are important for such virtual image optical systems Parts, which are partially reflective and partially transparent components. Users can see the front real scene through the light synthesizer, and they can also see the front virtual image through reflection at the same time. The present invention uses a vehicle head-up display (HUD) as an example. The structural differences and advantages and disadvantages between the conventional technology and the present invention are explained in detail.

The head-up display (referred to as HUD for short) is composed of an image projection system and a light synthesizer. When in use, the driver can simultaneously view the front scene through the light synthesizer and the virtual image information projected by the device without having to look down at the instrument panel below to increase Driving safety; and for the technical content of the conventional light synthesizer, please refer to Fig. 6, which uses a curved panel body 70 of the same thickness as the light synthesizer of the virtual image display. The curved panel body 70 is made of transparent material and has a uniform thickness. Therefore, the light does not shift when passing through, so the real scene in front can be seen through the curved panel body 70 without deformation. At the same time, in order to make the user see the reflected image clearly, conventional techniques are used on the curved surface 71 in front of the curved panel body 70 A "partially reflective, partially penetrated" semi-reflective film 710 is plated, and an anti-reflection coating 720 (AR coating) is plated on the rear curved surface 72, so that the semi-reflective film 710 can be used for higher reflection Rate (generally the reflectivity specification is set between 10% and 30%) to see the reflected image 712; and the anti-reflection film 720 function is used to suppress the reflection generated by the rear curved surface 72 The image 722 is used to solve the problem of double image (Double image) caused by the reflection of the front curved surface 71 and the rear curved surface 72 of the curved panel body 70; therefore, a conventional structure is in front of the curved panel body 70 Both the curved surface 71 and the rear curved surface 72 need to be coated, and the optical coating uses a vacuum evaporation technology, which is time-consuming to produce and expensive equipment, which results in increased costs and is a conventional disadvantage.

In addition, the virtual image display of the conventional technology is an asymmetric off-axis optical system. When the light B of the image projection system 30 is emitted, it passes through a single curved surface of the curved surface 71 in front of the curved panel body 70. The reflected light 711 forms the imaging 712, and the reflected light 721 on the rear curved surface 72 forms an unwanted noise image 722 on the other side, that is, ghosting; therefore, the quality of the imaging depends entirely on the reflection surface 71 of the light combiner 70 Aberration. Please refer to Figure 6. The system is asymmetrical up and down, resulting in different optical paths (such as the different lengths L1 and L2 in the figure), so the aberration is very large. If only the spherical surface is used to make the reflection of the optical combiner It is not enough to effectively reduce aberrations, so it can only be used for virtual image optical system design with a narrow field of view (FOV) and a short imaging distance L (<2 meters); if you want to reach the practical specifications of a head-up display (Horizontal FOV> 4 °, imaging distance L> 2 meters), the reflective curved surface 71 must use an aspheric surface or a free-form surface to effectively control the aberrations within an allowable range. However, it is very difficult to manufacture an aspherical or free-form optical synthesizer, and it is difficult to test. It is disadvantageous for the quantity of product tubes and the price is very high. This is another disadvantage of conventional technology.

Please refer to Figures 6 and 7. As the conventional imaging structure is used, the reflected image 712 and noise image 722 are close to each other. Although the anti-reflection film 720 can reduce the visibility of the noise image, it is used in darker applications In occasions (such as dark nights and dark tunnels), users can still see that the two images interfere with each other, so the sharpness is poor, which is another disadvantage of conventional usage.

The main object of the present invention is to design a light synthesizer that is easy to manufacture, convenient for quality control, and is independently installed in the inner space of the windshield of the car. The driver can pass through the light synthesizer and look out through the windshield of the car. At the same time, the virtual image in front is seen through reflection. In order to achieve this purpose, the present invention can be achieved by providing a substrate, a plate body made of a transparent material, and forming thick sides and thin sides on two opposite sides respectively. Side, but the substrate is formed as a spherical curvature on the plate surface, so it is formed as a spherical concave surface on one side and a spherical convex surface on the other side; and a compensation piece is set as a transparent plate body opposite to the substrate, and The two opposite sides are respectively formed as a thick side and a thin side. The plate surface of the compensation piece is formed with a spherical curvature. Therefore, a spherical concave surface is formed on one side and a spherical convex surface is formed on the other side. The radius of curvature is the same as the radius of curvature of the convex surface of the substrate; the above-mentioned substrate is mated to the thin side of the compensation sheet with the thick side, and the thickness of the compensation sheet is mated to the thin side of the substrate. The substrate is placed on the concave surface of the compensation plate with a convex surface, and a uniform gap is left between the substrate and the compensation plate. When the light of the image is projected by the image projection system of the virtual image display in the present invention, the substrate is spherical. The convex surface and the concave surface of the compensation sheet, that is, reflections are formed on the joint surfaces of the substrate and the compensation sheet adjacent to the gap. The reflection angle design of the optical system allows the light to reach the user's eye-box and pass through. The curved effect of the joint between the substrate and the compensation sheet forms a virtual image at the other end for the user to view various image information. In addition, for viewing the front real scene through the light synthesizer, the compensation sheet is located behind the substrate. The curvature is the same as that of the substrate. When the light passes through the substrate and the compensation sheet, it will pass through the same thickness of glass without distortion, so that the user can see the clear real scene in front.

Another object of the present invention is that in the wedge-shaped structure of the present invention, the thickness of the material on which the reflecting surface is located varies, and this asymmetry can just correct the optical path of such asymmetric off-axis optical systems. The aberration is reduced to a tolerable range; according to the optical simulation results, although the present invention uses a spherical surface, its ability to eliminate aberrations is no less than that of complex aspheric surfaces and free-form surfaces, which can be used for wide viewing angles and long imaging distances. Design of virtual image optical system; In addition, appropriate wedge angle can allow useless noise images to be reflected outside the human eye-box (Eye-box), without relying on coating to solve the ghost problem; secondly, in terms of manufacturing, the design of the present invention It only needs spherical surface, so it is easy to manufacture, easy to control quality, and no coating is needed. This not only makes the manufacturing easier, shortens the manufacturing process, saves the time and cost of manufacturing.

〔Usually〕

70‧‧‧ curved panel body

71‧‧‧ Surface

711‧‧‧Reflected light

710‧‧‧Semi-reflective film

712‧‧‧ Imaging

72‧‧‧ Surface

720‧‧‧Anti-reflective film

721‧‧‧Reflected light

722‧‧‧noisy image

B‧‧‧light

L‧‧‧ imaging distance

L1‧‧‧ length

L2‧‧‧ length

〔this invention〕

10‧‧‧ substrate

11‧‧‧thick side

12‧‧‧ thin side

13‧‧‧ concave

131‧‧‧ reflected light

14‧‧‧ convex

141‧‧‧Reflected light

20‧‧‧Compensation film

21‧‧‧thick side

22‧‧‧ thin side

23‧‧‧ concave

231‧‧‧Reflected light

24‧‧‧ convex

241‧‧‧Reflected light

30‧‧‧Image projection system

50‧‧‧ human eye

51‧‧‧Visible range

52‧‧‧ like points

53‧‧‧Noise image

60‧‧‧ Clearance

A‧‧‧ incident light

C‧‧‧light

d‧‧‧imaging distance

t‧‧‧thickness

r13‧‧‧curvature radius

r24‧‧‧curvature radius

Fig. 1 is a structural external view of the present invention.

Fig. 2 is an exploded view (1) of the structure of the present invention.

Fig. 3 is an exploded view (2) of the structure of the present invention.

Fig. 4 is a diagram of an embodiment of the present invention.

Figure 4-1 is another schematic diagram illustrating the structure of the present invention.

FIG. 5 is a schematic diagram of a situation where the normal image is in the visible range when the present invention is used, but the ghost image is reflected outside the visible range.

FIG. 6 is a schematic diagram of a conventional light synthesizer of a virtual image display similar to the present invention.

Figure 7 is a schematic diagram of normal images and noise images in conventional use.

Please refer to Figs. 1, 2, and 3. The light combiner of the virtual image display of the present invention includes: a substrate 10, which is a plate body made of transparent material, and is formed on two opposite sides as thick sides 11 and thin, respectively. Side 12, but the substrate 10 is formed with a spherical curvature on the surface of the plate, so it is formed as a spherical concave surface 13 on one side and a spherical convex surface 14 on the other side.

A compensation piece 20 is a transparent plate body opposite to the substrate 10, and is formed as a thick side 21 and a thin side 22 on two opposite sides, respectively. The plate surface of the compensation piece 20 is formed with a spherical curvature, so it is formed on one side. The concave surface 23 is a spherical surface, and the convex surface 24 is a spherical surface on the other side. The curvature radius of the concave surface 23 of the compensation piece is equal to the curvature radius of the convex surface 14 of the substrate.

The above-mentioned substrate 10 is aligned with the thin side 22 of the compensation sheet 20 with the thick side 11, and the thin side 12 of the substrate 10 is aligned with the thick side 21 of the compensation sheet 20, and the substrate 10 is attached to the compensation sheet with the convex surface 14. As shown in FIG. 4, a uniform gap 60 is left between the concave surface 23 of the substrate 20 and the compensation sheet 20, and the gap 60 is 50 μm or less.

Please refer to FIG. 2, FIG. 3 and FIG. 4. When the present invention is in use, when the image projection system 30 of the virtual image display projects image light, the spherical convex surface 14 of the substrate 10 and the concave surface 23 of the compensation sheet, that is, Reflections are formed on the joint surfaces of the substrate 10 and the compensation sheet 20 adjacent to the gap 60. The reflection angle design of the optical system allows the light to reach the driver's visible range 51 and pass through the curved surface of the joint between the substrate 10 and the compensation sheet 20 The imaging and magnification effects of 14 and 23 form a virtual image 52 at the other end for the driver to view various image information. As the curved surfaces 14 and 23 reflect and image, they are affected by the asymmetry of the thick side 11 and the thin side 12 and can be corrected. The optical path and aberrations of the off-axis optical system, so the virtual image position can be designed to be far away (the imaging distance d> 2 m from the human eye 50 to the image point 52), to achieve practical results.

In addition, in order to ensure that the real scene viewed directly by the user through the light synthesizer will not be distorted, the substrate 10 and the compensation sheet 20 may be made of the same material (that is, the same optical refractive index), and the spherical concave surface 13 of the substrate 10 and the compensation sheet 20 are not adjacent to each other. The relationship between the curvature radius of the spherical convex surface 24 is set as follows: Please refer to Figures 4 and 4-1. The curvature radius r24 of the spherical convex surface 24 is equal to the sum of the curvature radius r13 of the spherical concave surface 13 and the thickness t of the optical combiner. The light synthesizer forms a translucent material of the same thickness, so that the light C does not shift when it passes out of the substrate 10 and the compensation sheet 20, so a clear real scene can be obtained without distortion. In addition, since the thickness t of the optical combiner is much lower than the curvature radius r13 of the concave surface 13 of the substrate 10, it can be ignored; therefore, the curvature radius r13 of the spherical concave surface 13 and the convex surface 24 which are not adjacent between the substrate 10 and the compensation plate 20, When r24 is equal, the visible light synthesizer is a translucent body of equal thickness. In addition, for the convenience of production, the material (refractive index) of the substrate 10 and the compensation sheet 20 and the curvature radius of all spherical concave surfaces 13, 23 and convex surfaces 14, 24 (such as: r13, r24, the rest are not shown in detail) can be set. In order to be equal, the substrate 10 and the compensation sheet 20 are exactly the same components, which can be replaced with each other, which is advantageous for production and assembly, and can also reduce costs.

Please refer to FIG. 4, when the incident light A is projected from the image projection system 30 to the light combiner, the spherical concave surface 13, convex surface 14 of the substrate 10, and spherical concave surface 23 and convex surface 24 of the compensation sheet 20 sequentially generate reflections respectively. Light rays 131, 141, 231, and 241, among which the reflected light rays 141, 231 from the spherical convex surface 14 of the substrate 10 and the spherical concave surface 23 of the compensation plate 20 can be directed toward the human eye 50 visible range 51 (Eye-box), while the other two reflected light rays 131, 241 are Due to the design of the wedge-shaped angle, the noise image 53 is deflected away from the visible range 51 of the human eye 50 and will not be seen by the user (as shown in Figures 4 and 5), so it will not be seen as usual Ghosting phenomenon occurs; the aforementioned two reflected light rays 141,231 incident into the visible range 51 of the human eye 50 are caused by the extremely small gap 60 between the substrate 10 and the compensation sheet 20 (for example, less than 50 microns), so that the two reflected light rays 141,231 almost overlap It cannot be distinguished by human eyes, thus solving the problem of ghosting. Therefore, the present invention cleverly uses the wedge-shaped design of the substrate 10 and the compensation sheet 20 without having to rely on expensive coating technology to solve the ghosting problem as is known in the art.

In addition, the light (virtual image) seen by the human eye is synthesized by the two reflected light rays 141, 231 from the spherical convex surface 14 of the substrate 10 and the spherical concave surface 23 of the compensation plate 20, and its intensity is also twice that of a single reflective surface. Design of the reflectivity and incident angle, the overall reflectance intensity can exceed 10%, which has reached the practical threshold, so coating can be completely eliminated; if you want to enhance the reflectivity a little, you can also consider attaching a semi-reflective film to the substrate 10 The spherical convex surface 14 or the compensation sheet 20 is spherical concave surface 23, and the gap 60 is filled and bonded with transparent optical adhesive, so as to increase the reliability of the system; the semi-reflective film can be made by coating, and it can also be used Cheap film layers (such as window foils for cars) are attached.

Due to the special design of the present invention, it has the following advantages when used:

1. Because the spherical wedge structure of the present invention can effectively correct aberrations, the imaging quality is good, and it can be used to design a virtual image optical system with a wide viewing angle and a long imaging distance, which is the main advantage of the present invention.

2. In terms of manufacturing, since the design of the present invention is not a free-form surface or an aspheric surface, only a spherical surface is required. Therefore, the manufacturing is easy, the quality is easy to control, and the price is relatively low, which is another advantage of the present invention.

3. Due to the wedge-shaped angle design of the present invention, the angle of the light can be shifted without ghosting; and the overall reflectance of the two adjacent spherical surfaces of the substrate and the compensation sheet can meet the application requirements; therefore, neither the substrate nor the compensation sheet is required. Coating can save manufacturing costs.

The structural demonstration disclosed in the present invention is only a preferred embodiment of the present invention, and is not intended to limit the scope of implementation of the present invention; therefore, those who are familiar with the equivalent or easy changes made by this technique will not depart from the present invention. Equal changes and modifications made within the spirit and scope, such as adding other accessories, or simple replacement changes in materials, should still be within the scope of the features of the present invention.

Claims (9)

    A light synthesizer structure for a virtual image display includes: a substrate, which is a plate body made of a transparent material, and is formed on two opposite sides as a thick side and a thin side, respectively, and the substrate is formed into a spherical curvature on the plate surface. Therefore, a spherical concave surface is formed on one side and a spherical convex surface is formed on the other side; a compensation piece is a transparent plate body opposite to the substrate, and is formed as a thick side and a thin side on the two opposite sides respectively, and the compensation The plate surface of the sheet is also formed as a spherical curvature, so it is formed as a spherical concave surface on one side and a spherical convex surface on the other side; wherein the curvature radius of the concave surface of the compensation sheet is equal to the curvature radius of the convex surface of the substrate; The thick side of the substrate is aligned with the thin side of the compensation sheet, and the thin side of the substrate is aligned with the thick side of the compensation sheet, and the substrate is placed on the concave surface of the compensation sheet with a convex surface, and between the substrate and the compensation sheet, Leave a uniform gap.         According to the light synthesizer structure of the virtual image display device described in item 1 of the patent application scope, the optical refractive index of the substrate and the material of the compensation sheet are the same.         According to the light synthesizer structure of the virtual image display device described in item 1 of the scope of patent application, the gap between the substrate and the compensation sheet is less than 50 microns.         According to the light synthesizer structure of the virtual image display device described in item 1 of the patent application scope, a semi-reflective film is provided on one of the spherical convex surface of the substrate and the spherical concave surface of the compensation plate at the gap between the substrate and the compensation plate.         According to the light synthesizer structure of the virtual image display described in item 4 of the scope of patent application, the gap between the substrate and the compensation sheet is filled with glue.         According to the light synthesizer structure of the virtual image display described in item 4 of the scope of patent application, the reflectivity of the semi-reflective film is between 20% and 40%.         According to the light synthesizer structure of the virtual image display device described in item 1 of the scope of patent application, the curvature radius of the concave surface of the substrate and the convex surface of the compensation sheet are equal.         According to the light synthesizer structure of the virtual image display device described in item 1 of the scope of patent application, the relationship between the curvature radius of the concave surface of the substrate and the convex surface of the compensation plate is the sum of the curvature radius of the convex surface and the radius of curvature of the concave surface and the center thickness of the light combiner. .         According to the light synthesizer structure of the virtual image display device described in item 1 of the scope of patent application, the curvature radii of all the spherical surfaces of the substrate and the compensation sheet are equal.