CN210776039U - Miniaturized Short-Range Optical System - Google Patents

Abstract

The utility model provides a miniaturized short distance optical system, it includes a display screen, a reflective polarization component, a first phase delay piece, a part according to the preface pierces through partial reflection component, an at least optical element and locates a lens of above-mentioned component arbitrary side. The optical element may be a circular polarizer or a combination of a second phase retarder and a line polarizer. Display screen output image and after sending light, light penetrates between partial reflection component twice at reflective polarization component and part, makes light pass through first phase delay piece cubic, after light process cubic phase delay, light that phase delay passes through this part of penetration partial reflection component through the third time to carry out fourth time phase delay through optical element, light that phase delay passes through at last in a lens leading-in at least one people's eye, and only set up single lens and can let the utility model discloses an optical system whole thickness is littleer, reaches miniaturized purpose.

Description

Miniaturized Short-Range Optical System

technical field

The utility model relates to an optical system, in particular to a miniaturized short-distance optical system which can be applied to a head-mounted display.

Background technique

Head-mounted display (Head-mounted display) is a device used to display images and colors, usually in the form of goggles or helmets. It produces the effect of virtual reality and increases the sense of presence of the wearer.

1 is a schematic diagram of an optical system of a virtual reality head-mounted display. The display screen 10 projects an image, which is incident on an optical module 23 after an optical path with an optical path d. The optical module 23 is a single lens or a plurality of lenses. The combination is used to import the image into the user's human eye 24, assuming that the optical path d is 40mm, and the length of the head-mounted display is the optical path d plus the thickness of the optical module, eye relief, housing, etc. The eye mask and helmet on the head are a little bulky, which will cause a burden on the bridge of the nose, the top of the head, and the neck of the user and cannot be worn for a long time. The thickness of the display is reduced, which is convenient for users to wear and use.

Therefore, the present invention proposes a miniaturized short-distance optical system, which can not only shorten the distance of the optical system, but also expand the field of view and effectively solve the above problems. The specific structure and its implementation will be described in detail later. .

Utility model content

The main purpose of the present utility model is to provide a miniaturized short-distance optical system, in which optical elements such as a reflective polarizing element, a phase retarder, a partially penetrating and partially reflective element are arranged in front of the display screen and between the optical modules, and the Phase retardation and multiple reflections achieve approximately or the same length of optical path, thereby reducing the distance between the display and the optical module, which can ultimately be used to miniaturize head-mounted displays.

Another object of the present invention is to provide a miniaturized short-distance optical system, which can be used in any one of the reflective polarizer, the first phase retarder, the partially penetrating and partially reflective element, the second phase retarder, and the linear polarizer. A single lens is arranged on either side of the element, which can achieve the purpose of miniaturization under the premise of adjusting the focal length.

Another object of the present invention is to provide a miniaturized short-distance optical system, which can be applied to wide-angle lenses or wide-angle eyepieces on products such as head-mounted displays and game consoles. The thickness is shortened to achieve the advantages of short distance, large field of view, and good aberration correction.

In order to achieve the above-mentioned purpose, the present invention provides a miniaturized short-distance optical system, comprising: a display screen, which outputs images and emits polarized or non-polarized light; Partially penetrating and partially reflecting; a first phase retardation plate, disposed corresponding to the reflective polarizing element, receives the light partially penetrating the reflective polarizing element, and performs the first phase retardation; part of it penetrates part of the reflective element, Corresponding to the setting of the first phase retardation plate, part of the light after the first phase delay penetrates the part through the partially reflecting element, and part is reflected back to the first phase retardation plate for the second and third phase delays ; At least one optical element, set corresponding to the partially penetrating part of the reflective element, receives the light that partially penetrates the partially penetrating part of the reflective element and passes through the second and third phase delays, and performs a fourth phase delay, Then let the light passing through the fourth phase retardation pass through and the light passing through only two phase delays cannot pass through; and a lens, which is arranged on the reflective polarizing element, the first phase retardation plate, the partially penetrating and partially reflective element and the Either side of any of the optical elements to adjust focus and direct the image into at least one human eye.

According to the embodiment of the present invention, one or more pieces of flat glass may be further included between the display screen and the lens and between the lens and the human eye.

According to an embodiment of the present invention, the optical element includes: a second phase retardation plate, which is arranged corresponding to the partially penetrating and partially reflective element, and the receiving part penetrates the partially penetrating and partially reflective element and passes through the second and third times The phase-delayed light is subjected to the fourth phase retardation; and a linear polarizer is set corresponding to the second phase retardation plate. Four times the phase-delayed light passes through.

According to the embodiment of the present invention, the optical element is a circular polarizer.

According to the embodiment of the present invention, the light reflected by the partially penetrating and partially reflecting element back to the first phase retarder passes through the first phase retarder to reach the first phase retarder after the second phase delay of the first phase retarder. A reflective polarizing element, and the reflection is completed on the reflective polarizing element, so that the light is reflected back to the first phase retarder and a third phase retardation is performed, and then the light passes through the first phase retarder and the part of the The partially reflective element reaches the second retardation plate, and the lens can be disposed on either side of either the second retardation plate or the linear polarizer.

According to the embodiment of the present invention, the first, second, third and fourth phase delays are all increased by an odd multiple of 1/4 wavelength, so that the light reaching the human eye is delayed by an integer multiple of one wavelength in total .

According to the embodiment of the present invention, when the light emitted by the display screen and entering the reflective polarizing element is polarized light, it can be linearly polarized light, circularly polarized light or other polarization states, and the display screen and the reflective polarizing element are polarized light. According to the polarization of the display screen, at least a linear polarizer, a circular polarizer or a phase retarder can be added between the polarizing elements to adjust the polarization state of the display screen. The new material can be a film material or an optical coating, etc. The form of coating, coating or bonding is arranged on the display screen or the reflective polarizing element. The linearly polarized light can be converted into left circularly polarized light or right circularly polarized light after passing through the first phase retardation plate.

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According to the embodiment of the present invention, the visible range radius of the display screen is H, the total length of the optical system is TTL, the distance from the eye to the center of the surface of the nearest element of the optical system is E, and the half field of view of the optical system is The angle is ω, then

and

and

According to the embodiment of the present invention, the effective focal length of the optical system is F, the radius of curvature of the side of the lens close to the eye is R ₁ , and the radius of curvature of the side close to the display screen is R ₂ ,

Description of drawings

FIG. 1 is a schematic diagram of an optical path between a display screen of a head mounted display and a human eye in the prior art.

FIG. 2 is a schematic diagram of an embodiment of the miniaturized short-distance optical system of the present invention.

3 is an exploded view of an embodiment of the miniaturized short-distance optical system of the present invention

4A to 4C are flow charts of steps of the miniaturized short-distance optical system of the present invention.

5A to 5C are schematic views of embodiments of different configurations of a single lens in the miniaturized short-distance optical system of the present invention.

Explanation of reference numerals: 10-display screen; 12-reflective polarizing element; 14-first phase retardation plate; 16-partly penetrating part-reflecting element; 18-second phase retardation plate; 20-linear polarizer; 22-lens ; 23- optical module; 24- human eye; 26- flat glass.

Detailed ways

The utility model provides a miniaturized short-distance optical system, which is applied to a head-mounted display, especially a virtual reality system of the head-mounted display. Since it is worn on the user's head, if the volume is too large or too long, it is difficult to fix It will fall under the influence of gravity on the user's head, which will also cause a burden on the user's head and neck. Therefore, the smaller the size of the head-mounted display, the better, especially the length must be shortened, and the purpose of the present invention is That is to say, multiple optical elements are used to reflect the light multiple times, and only a single lens is arranged between these optical elements to adjust the focal length, and the overall optical system is shortened under the same length of optical path, so as to achieve the miniaturization of the head-mounted display. Purpose.

Please refer to FIG. 2 and FIG. 3 at the same time, which are a schematic diagram and an exploded view of an embodiment of the miniaturized short-range optical system of the present invention, respectively. In the miniaturized short-range optical system of the present invention, a display screen 10 and at least a The human eye 24 includes a reflective polarizer 12, a first phase retarder 14, a part of the penetrating part of the reflective element 16, a second phase retarder 18, a linear polarizer 20 and a lens 22 in sequence, wherein, The display screen 10 outputs images and emits light. The light is polarized light or non-polarized light. When the light is polarized light, the polarized light can be linearly polarized light, circularly polarized light or other polarization states. In this embodiment, The light is linearly polarized light. Further, the polarization direction of the linearly polarized light in this embodiment is perpendicular to the optical path; the reflective polarizing element 12 is arranged corresponding to the display screen 10, receives the polarized light emitted by the display screen 10, and polarizes the polarized light. The light is partially penetrated and partially reflected, especially the reflective polarizing element 12 used in the present invention includes two polarization directions that are perpendicular to the optical path and parallel to the optical path, so that the vertical polarized light can be penetrated and the horizontal polarized light can be reflected; the first phase retardation The sheet 14 is arranged corresponding to the reflective polarizing element 12 to receive the polarized light partially penetrated from the reflective polarizing element 12, and perform the first, second and third phase delays, wherein the first and third phase delays are The phase-delayed polarized light is directed toward the human eye 24, while the second phase-delayed polarized light is directed toward the display screen 10; the partially penetrating and partially reflecting element 16 is set corresponding to the first phase retardation plate 14, and is received through the first phase retardation plate 14. The light of a phase retardation plate 14 will partially reflect and partially penetrate the light passing through; the second phase retardation plate 18 is arranged corresponding to the partially penetrating part of the reflective element 16, and receives the light that partially penetrates the partially penetrating part of the reflective element 16, And carry out the fourth phase delay; the linear polarizer 20 is set corresponding to the second phase retardation plate 18, and the linear polarizer 20 is used to let the polarized light that has only undergone two phase delays not pass through and only let the polarized light that has undergone four phase delays pass through. Through, the lens 22 is arranged on either side of any element in the above-mentioned optical system, and the image is introduced into the human eye 24 .

The single lens 22 provided in the present invention can be a convex lens. As shown in FIG. 3 , the lens 22 can be provided on the reflective polarizing element 12 , the first phase retardation plate 14 , the partially penetrating and partially reflecting element 16 , the second Either side of the two-phase retardation plate 18 and the linear polarizer 20 is used to adjust the focal length, regardless of whether it is arranged between any two optical elements, the effect of shortening the optical system can finally be achieved. In the embodiment of FIG. 2 , The lens 22 is disposed on the left side of the linear polarizer 20 , close to the human eye 24 .

In particular, in the present invention, the fast and slow axes of the first phase retardation plate 14 and the penetration axis of the reflective polarizing element 12 form an angle of 45 degrees, which can increase the phase retardation of 1/4 wavelength.

In addition, the lens 22 in the present invention can be an aspherical lens, a Fresnel lens or a combination of multiple lenses.

4A to 4C for the specific steps in the present invention. First, in FIG. 4A , the display screen 10 outputs an image and emits polarized light to the reflective polarizing element 12 , and the reflective polarizing element 12 allows the polarized light to pass through the portion of the polarized light. After passing through the first phase retardation plate 14 , part of it is reflected back to the display screen 10 , while the partially transmitted polarized light passing through the reflective polarizing element 12 will undergo a first phase retardation after passing through the first phase retardation plate 14 , and then Reaching the partially penetrating and partially reflective element 16; then, please refer to FIG. 4B, the polarized light after the first phase delay partially penetrates at the partially penetrating and partially reflective element 16, and part is reflected back to the first phase retarder 14 for the second phase delay. The second phase retardation, the polarized light that partially penetrates the partial reflective element 16 is energy loss, and the polarized light that has undergone the first phase delay penetrates the first phase retardation plate 14 and reaches the reflective polarizing element 12; Referring to FIG. 4C, the reflective polarizer 12 reflects the polarized light that has undergone the second phase delay, reflects it back to the first phase retarder 14, performs a third phase delay, and then partially penetrates the partially reflective element 16, partially The penetrated polarized light (after the third phase delay) reaches the second phase retardation plate 18, and undergoes a fourth phase delay; The polarizer 20 is screened, and only the polarized light that has undergone four phase delays passes through the linear polarizer 20 and is guided into at least one eye 24 by the lens 22 .

Since the first phase retardation plate 14 and the second phase retardation plate 18 in the present invention are both odd-numbered multiples of the phase retardation of 1/4 wavelength, the retardation is an integer multiple of a wavelength after four phase retardations.

After passing through the first phase retardation plate 14, the linearly polarized light will be converted into circularly polarized light, including left circularly polarized light or right circularly polarized light. However, when part of the circularly polarized light is reflected back to the first phase retarder 14 by the partially penetrating and partially reflective element 16, it will become linearly polarized light, and then it will pass through the first phase retarder 14 and be converted into circularly polarized light. , however, after passing through the second phase retardation plate 18, it will still be converted into return-polarized light.

Between the display screen 10 and the reflective polarizing element 12 , at least a linear polarizer, a circular polarizer, or a phase retarder can be added according to the polarization of the display screen 10 to adjust the polarization state of the display screen 10 . It can be a thin film material or an optical coating, etc., which is disposed on the display screen 10 or the reflective polarizing element 12 in the form of coating, coating or bonding.

The utility model can achieve the effects of larger viewing angle, shortened system distance and good aberration correction. Please refer to FIG. 2, wherein the lens 22 is L, its effective focal length is f, the effective focal length of the optical system is F, and the half-view of the optical system is The field angle is ω, the visible range radius of the display screen 10 is H, R ₁ ˜ R ₂ are the curvature radii of the left and right sides of the lens 22 respectively, the distance from the eye (aperture) to the center of the surface of the nearest element of the optical system is E, and the The total length is TTL, and the following formula can be obtained:

The above formula (3) can achieve good aberration correction, while the formulas (1), (2), (4) can achieve the advantages of a larger viewing angle and a shortened system distance (thinning).

The specific experimental data can be obtained from the implementation of Fig. 2 as shown in Table 1:

Table I

其中C＝1/R，R为曲率半径。此外，表中f为光学系统的有效焦距，ω为光学系统的半视场角，H为显示屏的可视范围半径，f1为透镜的有效焦距，Nd为折射率(Refractive index)，Vd为阿贝数(Abbe number)或色散系数(V-number)。A, B, C, D, E, etc. in the above table are the parameters in the aspheric formula, and the aspheric formula is

where C=1/R, where R is the radius of curvature. In addition, f in the table is the effective focal length of the optical system, ω is the half angle of view of the optical system, H is the radius of the visible range of the display screen, f1 is the effective focal length of the lens, Nd is the refractive index (Refractive index), and Vd is Abbe number or dispersion coefficient (V-number).

In the present invention, the reflective polarizing element 12 and the partially penetrating and partially reflective element 16 may be coated on the lens 22 with a layer of coating with reflective polarizing function, or a lens with reflective polarizing function itself or in the form of a thin film Therefore, the present invention can attach the reflective polarizing element 12 to the first phase retardation plate 14, attach the reflective polarizing element 12 to the lens 22, and partially penetrate the The reflective element 16 is attached to the first phase retarder 14, the partially penetrating and partially reflective element 16 is attached to the second phase retarder 18, the partially penetrating and partially reflective element 16 is attached to the lens 22, etc., This results in a variety of different implementations.

In addition to the embodiment shown in FIG. 2 , various other embodiments of the configuration of the lens 22 are described in FIGS. 5A to 5C , but these embodiments do not limit the configuration method of the lens 22 in the present invention. , as long as the lens 22 is arranged on either side of at least one of the reflective polarizer 12 , the first phase retarder 14 , the partially penetrating and partially reflective element 16 , the second phase retarder 18 and the linear polarizer 20 Included in the scope of the present invention.

In the embodiment shown in FIG. 5A, the lens 22 is provided between the first phase retardation plate 14 and the partially penetrating and partially reflective element 16, and the partially penetrating and partially reflective element 16 is provided on the lens 22. In addition, the present utility model The second phase retardation plate 18 and the linear polarizer 20 can be set as one body. For example, as shown in FIG. 5A , the second phase retardation plate 18 and the linear polarizer 20 are on the same side of the same lens 22, which can be equivalent to For the function of the circular polarizer, the second phase retarder 18 and the linear polarizer 20 can be replaced by a circular polarizer. In this embodiment, a flat glass 26 is added before the polarized light enters the human eye 24 to play a protective role. The specific data of this embodiment are as follows in Table 2:

Table II

FIG. 5B shows another embodiment, the reflective polarizing element 12 is provided on the first phase retardation plate 14, and the lens 22 is provided between the first phase retardation plate 14 and the partially penetrating and partially reflective element 16, which is the same as the one shown in FIG. 5A. Similar to the embodiment, the second phase retardation plate 18 and the linear polarizer 20 can be replaced by a circular polarizer, and a flat glass 26 is added before the polarized light enters the human eye 24 . The specific data of this embodiment are as follows in Table 3:

Table 3

In the embodiment of FIG. 5C , the lens 22 is disposed between the reflective polarizing element 12 and the first phase retardation plate 14 , the reflective polarizing element 12 in this embodiment is disposed on the right side of the lens 22 , and the partially penetrating and partially reflective element 16 is It can be arranged on the left side of the first phase retardation plate 14 or the right side of the second phase retardation plate 18. Similar to the embodiment of FIG. 5A, the second phase retardation plate 18 and the linear polarizer 20 can use a circular polarizer. Instead, a flat glass 26 is added before the polarized light enters the human eye 24 . The specific data of this embodiment are as follows in Table 4:

Table 4

The present invention utilizes the polarization principle to refract the optical path internally in the optical system to achieve the effect of shortening the length of the optical system. As shown in the embodiments of FIG. 2 and FIG. 5A to FIG. The optical path to the optical module (not shown in the figure) in front of the human eye 24 undergoes multiple reflections. It is assumed that the length of each reflection of the light from the display screen 10 to the optical module adds up to the optical path d. In the prior art, the optical path d from the display screen 10 to the optical module 23 is almost the same, but because in the embodiments of FIG. 2 and FIG. 5A to FIG. This section of the optical path of the optical module is obtained by summing up multiple reflections, so in fact, the length from the display screen 10 to the optical module will be much smaller than the length from the display screen 10 to the optical module 23 in FIG. the purpose of the length of the system.

Table 5 below shows the calculation results of the embodiments of FIG. 2 and FIG. 5A to FIG. 5C incorporating the above formulas (1) to (4).

Table 5

To sum up, in the miniaturized short-distance optical system provided by the present invention, a plurality of optical elements are placed in sequence behind the display screen and in front of the optical module, and the length of the optical system is shortened by the use of multiple reflections of light. The phase retarder performs four phase delays, so that when the polarization state of the polarized light finally reaches the optical module and the polarization state emitted from the display screen at the beginning, the phase delay is an integer multiple of the wavelength. The utility model further utilizes the design of a single lens to achieve the purpose of short-distance miniaturization, and still maintains good aberration correction, and is suitable for wide-angle lenses or wide-angle eyepieces, and the viewing angle can reach more than 50 degrees.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the scope of implementation of the present invention. Therefore, all equivalent changes or modifications according to the features and spirit described in the scope of the claims of the present invention should be included in the protection scope of the present invention.

Claims (13)

1. A miniaturized short-range optical system, comprising:

a display screen for outputting images and emitting polarized or unpolarized light;

a reflective polarizing element arranged corresponding to the display screen for partially transmitting and partially reflecting the light;

a first phase retarder disposed corresponding to the reflective polarizer for receiving the light partially transmitted through the reflective polarizer and performing a first phase retardation;

a partial transmission partial reflection element corresponding to the first phase retardation plate, so that the light beam after the first time phase retardation partially penetrates the partial transmission partial reflection element, and partially reflects back to the first phase retardation plate for the second time and third time phase retardation;

at least one optical element, which is arranged corresponding to the partial penetration partial reflection element, receives the light which penetrates the partial penetration partial reflection element and passes through the second and third phase delays, performs the fourth phase delay, and allows the light which passes through the fourth phase delay to pass through but the light which passes through the two phase delays cannot pass through; and

and the lens is arranged on any side of any one of the reflective polarizing element, the first phase retarder, the partially-transmitting partially-reflecting element and the optical element and guides the image output by the display screen into at least one human eye.

2. The miniaturized short-distance optical system of claim 1, wherein one to many sheets of plate glass are disposed between the human eye and the lens, and one to many sheets of plate glass are disposed between the lens and the display screen, and one to many optical elements are disposed on the plate glass, and the optical elements are made of thin film material or optical coating and are disposed on the plate glass in a coating, coating or bonding manner.

3. A miniaturized short-range optical system as claimed in claim 1, characterized in that the optical element comprises:

a second phase delay plate, which is arranged corresponding to the partial transmission partial reflection element, receives the light which partially penetrates the partial transmission partial reflection element and passes through the second and third time phase delays, and carries out the fourth time phase delay; and

and a linear polarizer disposed corresponding to the second phase retarder, the linear polarizer being configured to let the light delayed by the second phase retarder not pass through, and let the light delayed by the fourth phase retarder pass through.

4. A miniaturized short-range optical system as claimed in claim 1, characterized in that the optical element is a circular polarizer.

5. A miniaturized short-distance optical system as claimed in claim 3, wherein the light reflected back to the first phase retarder by the partially transmissive partially reflective element passes through the first phase retarder after the second phase retardation by the first phase retarder to reach the reflective polarizer and is reflected by the reflective polarizer to be reflected back to the first phase retarder again for the third phase retardation, and then passes through the first phase retarder and the partially transmissive partially reflective element to reach the second phase retarder, and the lens is disposed on either side of the second phase retarder and the linear polarizer.

6. A miniaturized short-range optical system as in claim 3 wherein the first, second, third and fourth retardations are each increased by a phase retardation which is an odd multiple of 1/4 wavelengths such that the light reaching the human eye is retarded by an integer multiple of one wavelength.

7. The miniaturized short-distance optical system of claim 1, wherein the light transmitted from the display panel and entering the reflective polarizer is linearly polarized light or circularly polarized light, and one or more linear polarizers, circular polarizers or phase retarders are added between the display panel and the reflective polarizer according to the polarization of the display panel to adjust the polarization state of the display panel, and the linear polarizers, circular polarizers or phase retarders are thin film materials or optically coated films and are disposed on the display panel or the reflective polarizer in a coating, film coating or bonding manner.

8. A miniaturized short-distance optical system according to claim 7, wherein the linearly polarized light is converted into left circularly polarized light or right circularly polarized light after passing through the first phase retarder.

9. A miniaturized short-range optical system as claimed in claim 1, characterized in that the radius of the visible range of the display screen is H, the total length of the optical system is TTL,

10. the miniaturized short-distance optical system of claim 1 or 9, wherein the display screen has a radius of a visible range of H, the optical system has an overall length of TTL, the distance from the eye to the center of the surface of the nearest element of the optical system is E,

11. a miniaturized short-range optical system as claimed in claim 1, characterized in that the effective focal length of the optical system is F and the radius of curvature of the side of the lens which is closer to the eye is R₁The radius of curvature of the side near the display screen is R₂，

12. The miniaturized short-range optical system of claim 1, wherein the effective focal length of the optical system is F, the half field angle of the optical system is ω, the total length of the optical system is TTL,

13. a miniaturized short-range optical system as claimed in claim 1, characterized in that the lens is an aspherical lens, a fresnel lens or a combination of multiple lenses.

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