CN106291940B - A kind of design of virtual reality goggles and manufacturing method - Google Patents

Abstract

The invention relates to a design and manufacturing method of a virtual reality eyepiece, comprising: an eyepiece with a double-convex aspheric surface that meets the requirements of optical performance according to the designed field of view angle of about 90°; changing one surface into a plane base Fresnel surface, and The parameters of the plane base Fresnel surface and another surface parameter are simultaneously optimized to obtain an eyepiece with a plane base Fresnel surface; the plane base of the eyepiece is changed to an aspheric base, and the surface parameters of the aspheric base, Fresnel on it The tooth parameters and another surface parameter are optimized at the same time to obtain an eyepiece with an aspheric base Fresnel surface; all tooth tips of the aspherical base Fresnel surface in the designed eyepiece with an aspherical base Fresnel surface The connection becomes the basic curved surface, and the eyepiece with the basic curved surface is mass-produced by injection molding; the basic curved surface in the injected eyepiece with the basic curved surface is subjected to single-point diamond cutting, and the filling part of the basic curved surface due to the connection tooth tip is removed.

Description

Design and manufacturing method of a virtual reality eyepiece

technical field

The invention belongs to the technical fields of virtual reality, augmented reality, eyepiece imaging and the like.

Background technique

Virtual Reality (VR, Virtual Reality) is a three-dimensional virtual world generated by computer or mobile phone simulation, providing users with simulations of vision, hearing and other senses, so that users can observe in a timely and unlimited manner as if they were on the scene. objects in three-dimensional space. VR glasses are a key tool to realize virtual reality technology. Whether a VR glasses can make users feel immersive mainly depends on the design and manufacture of VR eyepieces. The shorter the focal length of the eyepiece, the greater the visual magnification, and the stronger the visual graininess; the larger the focal length, the smaller the magnification, and the worse the immersion. The existing eyepiece products mainly include two forms, one is a double-sided aspheric eyepiece, and the other is a flat base Fresnel eyepiece.

As the field of view increases, the thickness of the center and the edge of the double aspheric eyepiece differ greatly, so the processing difficulty increases sharply. Therefore, the field of view of the double aspheric eyepiece can generally only reach about 90°. The appearance of the plane-based Fresnel eyepiece solves the problem of the thickness ratio between the center and the edge, and the field of view can reach 110°, but with the increase of the field of view, the field curvature and coma will also increase. Imaging inconsistencies in the center and edges can make users feel dizzy. Therefore, designing and manufacturing a high-performance Fresnel eyepiece plays an important role in the application of VR field.

Contents of the invention

The object of the present invention is to provide a new VR eyepiece design and manufacturing method, so that the eyepiece can have a large field of view, avoid the problem of center and edge thickness ratio, and reduce field curvature and coma aberration when the large field of view is large , to meet the needs of strong immersion in the VR field. Technical scheme of the present invention is as follows:

A method for designing and manufacturing a virtual reality eyepiece, comprising the following steps:

1) According to the design requirements, design an eyepiece with a biconvex aspheric surface with a field of view of about 90° that meets the optical performance requirements;

2) Change one surface of the eyepiece designed in step 1) to a flat base Fresnel surface to increase the field of view of the system to meet the design requirements, and simultaneously modify the parameters of the flat base Fresnel surface and another surface parameter Optimized to obtain an eyepiece with a flat base Fresnel surface that meets the design requirements;

3) According to the parameters of the eyepiece with biconvex aspheric surface designed in step 1, change the plane base of the eyepiece with plane base Fresnel surface designed in step 2) into an aspheric base, for the aspheric base surface parameters, other The upper Fresnel tooth parameters and another surface parameter are optimized at the same time to obtain an eyepiece with an aspheric base Fresnel surface that meets the design requirements, so that the field curvature and coma of the system are reduced;

4) Connect all tooth tips of the aspheric base Fresnel surface in the designed eyepiece with the aspheric base Fresnel surface to form the base curved surface, and mass-produce the eyepiece with the base curved surface by injection molding;

5) Carry out single-point diamond cutting on the basic curved surface in the injection-molded eyepiece with basic curved surface, remove the filling part of the basic curved surface due to the connection of the tooth tip, and obtain the final aspherical base Fresnel surface, that is, the final aspherical surface Basal Fresnel facets for eyepieces.

2. The design and manufacturing method according to claim 1, characterized in that the tooth width of the Fresnel tooth is preferably in the range of 20 μm to 60 μm according to the imaging performance, and the method of equal tooth width or equal tooth height can be adopted.

3. The design and manufacturing method according to claim 1, characterized in that, in order to further thin the eyepiece thickness and reduce the field curvature and coma aberration when the large field of view is reduced, the other surface is also changed into a plane base Fresnel surface or an aspheric base Fresnel surface.

The present invention adds a Fresnel structure to the aspheric surface base of the VR eyepiece, effectively thins the center thickness of the VR eyepiece, and reduces the field curvature and coma of the large field of view system, and the imaging quality is obviously improved. It makes the wearer have a better sense of immersion. At the same time, a processing method combining injection molding and single-point diamond turning is proposed, which not only ensures the low-cost and large-scale production of devices, but also ensures the processing of high-efficiency and high-precision Fresnel structures.

Description of drawings

Figure 1 Structural diagram of aspheric base Fresnel VR eyepiece

Figure 2(a) and (b) are the base surface and the aspheric base Fresnel surface after cutting respectively

Figure 3 Structural diagram of biconvex aspheric VR eyepiece (Scheme 1)

Figure 4 Biconvex aspherical VR eyepiece diffuse spot (Scheme 1)

Figure 5 Field curvature distortion diagram of biconvex aspheric VR eyepiece (Scheme 1)

Figure 6 Plane Fresnel VR eyepiece structure diagram (Scheme 2)

Figure 7 Diffusion pattern of plane Fresnel VR eyepiece (Scheme 2)

Figure 8 Field curvature distortion diagram of the plane Fresnel VR eyepiece (Scheme 2)

Figure 9 Diffusion pattern of aspherical base Fresnel VR eyepiece (Scheme 3)

Figure 10 Field curvature distortion diagram of Fresnel VR eyepiece with aspherical base (Scheme 3)

Figure 11 Structural diagram of double-sided Fresnel VR eyepiece (Scheme 4)

Figure 12 Diffusion pattern of double-sided Fresnel VR eyepiece (Scheme 4)

Figure 13 Mi field curvature distortion diagram of double-sided Fresnel VR eyepiece (Scheme 4)

Detailed ways

The imaging principle of the VR eyepiece is that the light emitted by the pixels on the screen passes through the eyepiece and enters the human eye in parallel. When the human eye observes at the exit pupil position, it is equivalent to imaging the image on the screen at infinity. The images observed by the left and right eyes come to two screens respectively, thereby producing a 3D visual effect. If the field curvature and coma aberration at the edge of the system are too large, the sharpness of the edge image and the center image will be inconsistent, which will cause the user to feel dizzy during the use of VR glasses, thus losing the meaning of a large field of view. The present invention proposes a design scheme of the aspherical base Fresnel eyepiece, which can greatly reduce field curvature and coma aberration caused by a large viewing angle.

The specific structure of the present invention is shown in Figure 1. Fresnel teeth are superimposed on one aspheric surface or two aspheric surfaces of the VR lens with aspheric design, that is, a series of sawtooth structures are distributed in the circular diameter direction of the device. One side is a vertical side of a vertical aspheric surface, the other is a curved surface side with a certain curvature, and the distance between each tooth is the tooth pitch. The Fresnel teeth rotate in a circular circumferential direction to form a ring structure. There are two distribution forms of Fresnel teeth: one is equal tooth width, generally the tooth height of Fresnel teeth will become smaller and smaller as the edge of the curved surface goes to the center; the other is constant tooth height, this structure starts from the curved surface The pitch of the Fresnel teeth increases progressively from the edge to the center. From the perspective of design and processing, it is more common to choose Fresnel teeth with equal tooth width.

In the design, based on the optimally designed biconvex aspheric eyepiece, firstly change one of the surfaces to a plane base Fresnel surface to increase the system field of view, and then change the Fresnel plane base to an aspheric base , and finally optimized into an aspheric base Fresnel eyepiece to reduce system field curvature and coma. In order to further thin the thickness of the eyepiece and reduce the field curvature and coma aberration when the field of view is large, the scheme can be further expanded, and another surface can be changed to a flat base Fresnel surface or an aspheric base Fresnel surface. In the design, special attention should be paid to the Fresnel tooth width. Too small tooth width will cause visual diffraction, resulting in blurred imaging and many difficulties in processing; while too large tooth width will have no effect on imaging performance. Much improvement. Considering comprehensively, the Fresnel tooth width can be in the range of 20 μm to 60 μm. In specific implementation, the optical design part can be easily completed by design engineers with certain experience.

There are two main forms of Fresnel tooth machining: injection molding and single point diamond turning. Injection molding can meet the needs of mass production, and devices can be mass-produced at low cost. However, due to the small Fresnel tooth pitch and the structural characteristics of vertical truncated teeth, the structure after injection molding is difficult to deform due to shrinkage. Ensure the high-precision molding of Fresnel teeth, and the smaller the Fresnel tooth width, the more serious the surface shrinkage after injection molding, and the more difficult it is to guarantee the surface accuracy. For the Fresnel curved surface of the aspheric base proposed by the present invention, in the case of ensuring the processing efficiency, the processing surface shape accuracy should be improved as much as possible. The present invention proposes a processing method combining injection molding and single-point diamond turning, that is, firstly, the base curved surface is injection-molded, Only the Fresnel teeth are then machined using single point diamond turning. The basic curved surface is a surface formed by connecting Fresnel tooth tips in the aspheric base Fresnel surface, as shown in Figure 2. The injection-molded basic surface is filled with Fresnel teeth. Therefore, only the filling part needs to be removed during single-point diamond turning to form the final required aspheric base Fresnel surface. This processing method not only takes into account the low cost and mass production requirements of injection molding, but also ensures the processing of high-efficiency and high-precision Fresnel structures.

In the specific implementation case, the technical indicators of the proposed VR eyepiece are: screen size: 5.5 inches, focal length: 38mm, field of view: 105°, working distance: 15mm, exit pupil diameter: 10mm. The biconvex aspheric structure design scheme (Scheme 1) is shown in Figure 3. Due to the limitation of the biconvex aspheric structure, the field of view angle can only be 90°. If the angle is larger, the thickness ratio between the center and edge of the lens will Too large makes injection molding very difficult. Change a surface in Scheme 1 to a flat base Fresnel for optimization, and increase the field of view angle to 105° to obtain the structure diagram shown in Figure 6 (Scheme 2). In order to reduce field curvature and coma aberration caused by the large field of view, the Fresnel base was further optimized, and finally an aspheric base Fresnel eyepiece (Scheme 3) was obtained, as shown in Figure 1. In order to further reduce the thickness ratio between the center and the edge of the device, the other surface is changed to a plane substrate Fresnel, as shown in Figure 11 (Scheme 4).

The imaging diagrams of the diffuse spots of the four schemes are shown in Figure 4, Figure 7, Figure 9 and Figure 12 respectively; the field curvature diagrams are shown in Figure 5, Figure 8, Figure 10 and Figure 13 respectively. The main structural parameters, maximum/minimum speckle and field curvature of the four schemes are summarized in Table 1. It can be seen that the scheme of adding an aspheric base Fresnel surface can effectively increase the field of view and reduce the field of view at the same time. The thickness ratio of the center and edge of the small lens reduces optical errors such as blurring spots and field curvature.

Attached Table 1 Comparison Table of Structural Parameters and Optical Performance Parameters of Each Scheme

Program Field of view Edge thickness center thickness maximum diffuse spot least diffuse spot field curvature Option One 90° 2.0mm 16.3mm 305.0um 107.0um <5.0mm Option II 105° 1.8mm 4.0mm 227.0um 88.0um <5.0mm third solution 105° 1.8mm 7.0mm 183.0um 69.0um <2.0mm Option four 105° 1.8mm 4.0mm 184.0um 62.0um <2.0mm

Claims (3)

1. a kind of virtual reality goggles design and manufacturing method, include the following steps：

1) according to design requirement, design field angle meets the eyepiece aspherical with biconvex of optical performance requirements at 90 °；

2) surface in the eyepiece designed by step 1) is changed to planar substrates Fresnel surface, to increase system field angle to symbol Design requirement is closed, and parameter to planar substrates Fresnel surface and another surface parameter optimize simultaneously, obtains meeting design and want The eyepiece with planar substrates Fresnel surface asked；

3) step 2) design is had planar substrates by the parameter with the aspherical eyepiece of biconvex designed by step 1) The planar substrates of the eyepiece of Fresnel surface are changed to aspheric substrate, to aspheric substrate Surface Parameters, Fresnel tooth parameter thereon And another surface parameter is carried out at the same time optimization, obtains the eyepiece with aspheric substrate Fresnel surface for meeting design requirement, So that the system curvature of field and coma are reduced；

4) all crowns of aspheric substrate Fresnel surface in the designed eyepiece with aspheric substrate Fresnel surface are connected It is connected into as basic curved surface, and uses eyepiece of the injection molding manner batch production with base curve；

5) single point diamond cutting processing is carried out to the base curve in the eyepiece with base curve of injection formed, removed because even The base curve fill part for connecing crown obtains final aspheric substrate Fresnel surface to get to finally with aspheric base The eyepiece of bottom Fresnel surface.

2. design according to claim 1 and manufacturing method, which is characterized in that the facewidth of Fresnel tooth is according to imaging performance Selected in 20 μm~60 μ ms, using etc. the facewidth or wait the high mode of teeth.

3. design according to claim 1 and manufacturing method, which is characterized in that for eyepiece thickness and reduction is further thinned Another surface is also changed to planar substrates Fresnel surface or aspheric substrate Fresnel surface by curvature of field when big visual field and coma.