TWM596874U - Short-distance optical system - Google Patents

Abstract

A short-distance optical system applied to a miniature head-mounted display, which is provided with a partially penetrating partial reflection element, a first phase retarder, a second phase retarder and a reflective polarizing element in order in front of the display screen The emitted light is derived through multiple phase delays and reflections, so that the light can obtain the shortest distance between the display screen and the optical system under the approximate optical path to achieve the miniaturization of the head-mounted display. The creative system uses a combination of a half-wavelength phase retarder and a quarter-wavelength phase retarder as the first phase retarder and the second phase retarder, thereby improving the efficiency of the phase delay conversion of the phase retarder to different wavelengths, thereby Improve image clarity.

Description

Short range optical system

This creation relates to an optical system, especially a short-distance optical system that can be applied to miniature head-mounted displays.

Head-mounted display (Head-mounted display) is a very popular virtual reality (VR) product recently, usually in the form of an eye mask or helmet, close the display to the user's eyes, and adjust the focus through the optical path to Projecting images to the eyes at close range produces a virtual image magnification effect, increasing the sense of presence.

Fig. 1 is a schematic diagram of an optical system of a virtual reality head-mounted display. The display screen 10 projects an image and enters the optical module 20 after a period of the optical path with an optical path of d. The optical module 20 is a single lens Or a combination of multiple lenses to import images into the user's eye 22, 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 and the appropriate eye distance , The shell, etc., the sum of which is slightly bulky for the eye mask and helmet worn on the head, which will cause a burden on the nose bridge, the top of the head, and the neck of the user and cannot be worn for a long time, so the current technology is committed to the optical The length of the system is shortened, so that the thickness of the head-mounted display is reduced, which is convenient for users to wear.

In addition, in order for the virtual images provided by the head-mounted display to be visually reproduced, high-quality display quality must be obtained. Therefore, this creation proposes a short-distance optical system. In addition to shortening the distance of the optical system, it can also improve the clarity of the displayed image and effectively solve these problems. The specific architecture and implementation will be described in detail later.

The main purpose of this creation is to provide a short-distance optical system that uses the first and second phase retarders composed of a half-wave phase retarder and a quarter-wave phase retarder to extend the phase of the phase retarder Delay the effective band, and improve the conversion efficiency of the phase retarder for different wavelengths to eliminate image chromatic aberration and improve image clarity.

Another purpose of this creation is to provide a short-distance optical system, which is provided with optical elements such as a partially reflective partial penetrating element, first and second phase retarders, reflective polarizing element, etc. in front of the display screen of the head-mounted display. The head-mounted display is miniaturized by using multiple phase delays and reflections of light to achieve an approximate optical path length, thereby shortening the distance between the display screen and the optical system.

To achieve the above purpose, the present invention provides a short-distance optical system, which is applied to a miniature head-mounted display with a display screen, and the display screen is used to output images and light. The short-distance optical system includes: a part of the reflective part penetrating the element, Corresponding to the setting of the display screen, receiving the light from the display screen, and allowing the light to partially penetrate and partially reflect; a first phase retarder, corresponding to the partial reflection part penetrating element setting, receiving the partial penetrating part reflection part penetrating element light , Phase delay to form the first polarized light; a second phase retarder, corresponding to the first phase retarder set, receives the first polarized light, and performs phase delay to form the second polarized light; and a reflective polarizing element , Corresponding to the setting of the second phase retarder, receiving the second polarized light, partially reflecting the second polarized light, so that the second polarized light reflected by the reflective polarizing element passes through the first phase retarder, the second phase retarder and partial reflection After partially penetrating the element, it is reflected back to the reflective polarizing element and penetrates out; where, when the first phase retarder is a half-wavelength retarder, the second phase retarder corresponds to a quarter-wavelength retarder When the first phase retarder is a quarter-wave retarder, the second phase retarder corresponds to a half-wave retarder.

According to the embodiment of the present invention, it further includes a lens, which is disposed on any side of any one of the partially reflective partially penetrating element, the first phase retarder, the second phase retarder, and the reflective polarizing element to The output image is imported into the eyes of at least one person.

Further, the lens may be selected from spherical lenses, aspheric lenses, Fresnel lenses, and multi-piece lenses of combinations thereof.

Further, one or more pieces of flat glass may be included between the human eye and the lens, and one or more pieces of flat glass may be included between the lens and the display screen.

Still further, the partially reflecting and partially penetrating element, the first phase retarder, the second phase retarder and the reflective polarizing element may be thin film materials or optical coatings, and are provided on the plate glass in the form of coating, coating or bonding .

According to the embodiment of the present invention, the light emitted from the display screen and entering the partially reflecting part of the penetrating element is circularly polarized light.

According to the embodiment of the present invention, it further includes at least one linear polarizer, circular polarizer or phase retarder for adjusting the polarization state of the display screen, and the linear polarizer, circular polarizer and phase retarder are thin film materials or optical coatings, And in the form of coating, coating or bonding on the display screen or part of the reflective part of the penetrating element.

According to the embodiment of the present invention, the light emitted by the display screen is linearly polarized light, and a third phase retarder is further provided between the display screen and the partially reflective part penetrating element, so that the linearly polarized light is phased through the third phase retarder After the delay, it is converted into circularly polarized light.

According to the embodiment of the present invention, the light emitted by the display screen is unpolarized light, and a linear polarizer and a third phase retarder are further provided between the display screen and the partially reflective partial transmission element. The linear polarizer is provided on the display screen and Between the third phase retarders, the unpolarized light is linearly polarized after passing through the linear polarizer. The linearly polarized light is then phase-delayed through the third phase retarder and then converted into circularly polarized light.

Further, the third phase retarder may be a quarter-wave retarder.

According to the embodiment of the present invention, the light emitted from the display screen is unpolarized light, and a circular polarizer is further provided between the display screen and the partially reflective part penetrating element, so that the unpolarized light is converted into circular polarized light after passing through the circular polarizer .

According to the embodiment of the present invention, the second polarized light reflected by the reflective polarizing element undergoes phase delay through the first phase retarder and the second phase retarder to form third polarized light, and the third polarized light passes through the part After the partial reflection of the reflecting part penetrates through the element, the first phase retarder and the second phase retarder perform phase delay to form fourth polarized light, and the fourth polarized light penetrates the reflective polarizing element; wherein, the first polarized light , The second polarized light and the fourth polarized light are linearly polarized light, and the third polarized light is circularly polarized light.

The detailed description will be given below through specific embodiments, so that it is easier to understand the purpose, technical content, characteristics and effects of the creation.

This creation provides a short-distance optical system for miniature head-mounted displays. It uses multiple optical elements to reflect light multiple times. In addition, these optical elements are equipped with phase retarders at different angles, which can effectively improve the image. Clarity, eliminate image chromatic aberration, and can utilize multiple phase delays and reflections of light to achieve an optical path of approximate length, thereby shortening the distance between the display device and the optical system, miniaturizing the head-mounted display.

Please refer to FIG. 2 and FIG. 3, which are respectively a schematic diagram and an exploded view of the short-distance optical system provided by the first embodiment of creation. As shown in FIG. 2, the short-distance optical system of this embodiment is disposed in a miniature head-mounted display, and is located at the front end of the display screen 10, and a part of the reflective part penetrating element 11 is sequentially arranged corresponding to each other from the side adjacent to the display screen 10 1. A first phase retarder 12, a second phase retarder 13, a reflective polarizing element 14, and a lens 15. In this creation, the first phase retarder 12 and the second phase retarder 13 are a combination of a half-wave phase retarder and a quarter-wave phase retarder; specifically, when the first phase retarder 12 is set It is a half-wave phase retarder, the second phase retarder 13 is correspondingly set as a quarter-wave phase retarder, and when the first phase retarder 12 is set as a quarter-wave phase retarder, the second phase The retarder 13 is correspondingly set as a half-wave phase retarder.

As shown in FIG. 3, in this embodiment, the display screen 10 outputs an image and emits light 1, which can be polarized light or unpolarized light. When light 1 is polarized light, the polarized light can be linearly polarized Light, circularly polarized light or other polarization states. Partially reflecting partial penetrating element 11 is provided corresponding to display screen 10, receives incident light 1 and partially reflects light 1 passing back to display screen 10, and the remaining part penetrates partially reflecting partial penetrating element 11; in a preferred embodiment In the case, the partially reflective and partially penetrating element 11 is half reflective and half transparent. The first phase retarder 12 is disposed corresponding to the partially reflective partial penetrating element 11, receives the light 1 penetrating the partially reflective partial penetrating element 11, and performs the first phase retardation to form the first polarized light 2. The second phase retarder 13 is disposed corresponding to the first phase retarder 12, receives the first polarized light 2 of the first phase retarder 12, and then performs the second phase delay to form the second polarized light 3. The reflective polarizing element 14 is provided corresponding to the second phase retarder 13, receives the second polarized light 3 of the second phase retarder 13, and totally reflects the second polarized light 3. The second polarized light 3 reflected by the reflective polarizing element 14 passes through the second phase retarder 13 and the first phase retarder 12 for the third and fourth phase delays to form the third polarized light 4. After the third polarized light 4 is partially reflected by the partially reflecting and partially penetrating element 11, it passes through the first phase retarder 12 and the second phase retarder 13 in sequence for the fifth and sixth phase delays to form the fourth For the polarized light 5, the phase difference of the fourth polarized light 5 meets the penetration condition of the reflective polarizing element 14. Therefore, the reflective polarizing element 14 can pass the fourth polarized light 5 after six phase delays. The lens 15 can be disposed on either side of any element in the above-mentioned optical system to introduce the image output from the display screen 10 into the human eye 22.

The partially penetrating partial reflection element 11, the first phase retarder 12, the second phase retarder 13, and the reflective polarizing element 14 provided in this creation can each be independent elements, as shown in FIG. 2, these optical The element may also be a thin film material or optical coating, and is provided on one or more sheets of flat glass 16 in the form of coating, coating, or bonding, and one or more sheets of flat glass 16 may be correspondingly disposed between the human eye 22 and the lens 15, or It is between the lens 15 and the display screen 10. In the first embodiment, the partially penetrating partial reflection element 11 is an independent partially penetrating partial reflection element, and the first phase retarder 12, the second phase retarder 13 and the reflective polarizing element 14 are bonded or The coating method is set on the same flat glass 16.

The single lens 15 provided in this creation may be a convex lens. As shown in FIG. 2, the lens 15 may be provided in the partially penetrating and partially reflecting element 11, the first phase retarder 12, the second phase retarder 13 and Either side of the reflective polarizing element 14 is used to adjust the focal length, regardless of whether it is placed between any two of the above-mentioned optical elements, in the end, the effect of shortening the optical system can be achieved, and in the first embodiment, the lens 15 is provided on the reflection The left side of the polarizing element 14 is close to the human eye 22. In addition, the lens 15 in the present creation may be a spherical lens, an aspheric lens, a Fresnel lens or a multi-piece lens of the foregoing combination.

Since the first phase retarder 12 and the second phase retarder 13 are a combination of a quarter-wave retarder and a half-wave retarder in this creation, the light is reflected twice by going back on the transmission optical path As a result, there will be six phase delays, a total of two and one-quarter wavelength delays.

Taking the first phase retarder 12 and the second phase retarder 13 as quarter-wave retarder and half-wave retarder respectively as an example, the light 1 emitted by the display screen 10 in the above embodiment will be described in detail For the transfer process when entering the optical system, please refer to Figure 4A to Figure 4C. First, in FIG. 4A, the display screen 10 of this embodiment outputs an image, and the emitted light 1 is operated in the polarization state of circularly polarized light. When the circularly polarized light is received by the partially reflecting and partially penetrating element 11, it is partially reflected The partially-transmissive element 11 partially transmits the circularly polarized light to the first phase retarder 12 and partially reflects back to the display screen 10, and the circularly polarized light penetrating the partially-reflected partially penetrating element 1 passes through the first phase retarder 12, It will increase the quarter-wavelength phase delay and turn into linearly polarized light (first polarized light 2). After the linearly polarized light passes through the second phase retarder 13, the linearly polarized light will be delayed by one phase difference, and its phase will be delayed to four. At the third wavelength, the linearly polarized light (second polarized light 3) is totally reflected at the reflective polarizing element 14.

Next, in FIG. 4B, the linearly polarized light (second polarized light 3) reflected by the reflective polarizing element 14 returns to the second phase retarder 13 and the first phase retarder 12 again, increasing the quarter-wave retardation Then, circularly polarized light (third polarized light 4) is formed, and then the circularly polarized light is partially penetrated and partially reflected at the partially penetrating partial reflection element 11.

Then, in FIG. 4C, the circularly polarized light (third polarized light 4) partially reflected by the partially penetrating partial reflection element 11 passes through the first phase retarder 12 and the second phase retarder 13 in sequence, increasing by four points After the phase of one wavelength is delayed, it is converted into linearly polarized light (fourth polarized light 5). Then, the linearly polarized light reaches the reflective polarizing element 14, the reflective polarizing element 14 penetrates the linearly polarized light after multiple phase delays and enters the lens 15, and finally, the lens 15 guides the transmitted light into at least one human eye 22 .

In one embodiment of the above embodiment, the light 1 emitted by the display screen 10 is circularly polarized light with a phase difference of 45 degrees, and the first phase retarder 12 is a quarter-wavelength retarder, which can make circularly polarized light The polarization state of is delayed by a phase difference of 45 degrees, therefore, the first polarized light 2 is linearly polarized light with a phase difference of 90 degrees. The second phase retarder 13 is a half-wave phase retarder, which can delay the polarization state of linearly polarized light by another 90 degree phase difference, then the second polarized light 3 is linearly polarized light with a 180 degree phase difference, and the third The polarized light 4 is circularly polarized light with a phase difference of 315 degrees, and the fourth polarized light 5 is linearly polarized light with a phase difference of 90 degrees. In this embodiment, the reflective polarizing element 14 only provides 90° or 270° phase difference polarized light transmission, so the fourth polarized light 5 can penetrate the reflective polarizing element 14.

In another embodiment of the above embodiment, the light 1 emitted by the display screen 10 is circularly polarized light with a phase difference of 135 degrees, and the first phase retarder 12 is a quarter-wave retarder, which can make circular polarization The polarization state of the light is delayed by a phase difference of 45 degrees, so the first polarized light 2 is linearly polarized light with a phase difference of 180 degrees. The second phase retarder 13 is a half-wave phase retarder, which can delay the polarization state of linearly polarized light by another 90 degree phase difference, then the second polarized light 3 is linearly polarized light with a phase difference of 270 degrees, and the third The polarized light 4 is circularly polarized light with a phase difference of 45 degrees, and the fourth polarized light 5 is linearly polarized light with a phase difference of 180 degrees. In this embodiment, the reflective polarizing element 14 also only provides 180° phase difference polarized light transmission, so the fourth polarized light 5 can penetrate the reflective polarizing element 14.

In addition, between the display screen 10 and the partially reflective partial penetrating element 11, one or more linear polarizers, circular polarizers or phase retarders can be added according to the polarization of the display screen 10 to adjust the display screen 10 The polarization state, and the material of the linear polarizer, circular polarizer and phase retarder can be thin-film materials or optical coatings, which can be applied to the display screen 10 or part of the reflective part penetrating element 11 by coating, coating or bonding on.

Please refer to FIG. 5, which is an exploded view of the short-distance optical system provided in the second embodiment of the present invention. In this embodiment, the first phase retarder 12 and the third phase retarder 17 are quarter-wave phase retarders, and the second phase retarder 13 is half-wave retarder. . If the light 1 emitted by the display screen 10 is not circularly polarized light but linearly polarized light, a third phase retarder 17 needs to be added after the display screen 10 to cause the linearly polarized light emitted by the display screen 10 to undergo the first phase delay, The quarter-wave phase delay is increased, and it is converted into circularly polarized light 1'. Next, the transfer state after the circularly polarized light 1'enters the partially reflective partially penetrating element 11 is the same as in the first embodiment described above. The partially reflective partially penetrating element 11 partially reflects and partially penetrates the circularly polarized 1'light. The transmitted circularly polarized light is successively passed through the first phase retarder 12 for a second phase delay, adding a quarter-wavelength phase delay, and converted into linearly polarized light (first polarized light 2). The linearly polarized light then passes through the second The phase retarder 13 performs the third phase delay, and its phase is delayed to a wavelength. Then, the linearly polarized light (second polarized light 3) is totally reflected by the reflective polarizing element 14 and returned to the second phase retarder 13 and the first phase retarder 12, and after the fourth and fifth phase delays, the transition It is circularly polarized light (third polarized light 4). The circularly polarized light penetrates the first phase retarder 12 and reaches the partially reflecting partially penetrating element 11, and then is partially reflected back by the partially reflecting partially penetrating element 11 back to the first phase retarder 12 and the second phase retarder 13, for the sixth After the second and seventh phase delays, it is converted into linearly polarized light (fourth polarized light 5). At this time, the phase difference of the linearly polarized light meets the penetration condition of the reflective polarizing element 14, and can penetrate the reflective polarizing element 14 and enter the lens, and then be introduced into at least one human eye 22.

In an implementation form in the second embodiment, the light 1 emitted by the display screen 10 is linearly polarized light with a phase difference of 0 degrees, and the third phase retarder 17 is a quarter-wave retarder. Therefore, After the first phase delay, the polarization state of the linearly polarized light can be delayed by a phase difference of 45 degrees, and circularly polarized light with a phase difference of 45 degrees can be formed. The first phase retarder 12 is a quarter-wave phase retarder. Therefore, after the second phase retardation, the polarization state of the circularly polarized light can be delayed by 45 degrees out of phase and converted into linear polarization with a phase difference of 90 degrees. Light (first polarized light 2). The second phase retarder 13 is a half-wave phase retarder. Therefore, after the third phase retardation, the polarization state of the linearly polarized light can be delayed by another 90-degree phase difference and converted into a line with a 180-degree phase difference. Polarized light (second polarized light 3), and after the fourth and fifth phase delays, it can be converted into circularly polarized light with a phase difference of 315 degrees (third polarized light 4). After the seventh phase delay, it is converted into linearly polarized light with a phase difference of 90 degrees (fourth polarized light 5). In this embodiment, the reflective polarizing element 14 only provides 90° or 270° phase difference polarized light transmission, so the fourth polarized light 5 can penetrate the reflective polarizing element 14.

In another embodiment of the second embodiment, the light 1 emitted by the display screen 10 is linearly polarized light with a phase difference of 90 degrees, and the third phase retarder 17 is a quarter-wave retarder. Therefore, After the first phase delay, the polarization state of the linearly polarized light can be delayed by a phase difference of 45 degrees, and circularly polarized light with a phase difference of 135 degrees can be formed. The first phase retarder 12 is a quarter-wave phase retarder. Therefore, after the second phase retardation, the polarization state of the circularly polarized light can be delayed by 45 degrees out of phase and converted into linear polarization with 180 degrees out of phase. Light (first polarized light 2). The second phase retarder 13 is a half-wave phase retarder. Therefore, after the third phase retardation, the polarization state of the linearly polarized light can be delayed by another 90-degree phase difference and converted into a line with a 270-degree phase difference Polarized light (second polarized light 3), and after the fourth and fifth phase delays, it can be converted into circularly polarized light with a phase difference of 45 degrees (third polarized light 4). After the seventh phase delay, it is converted into linearly polarized light with a phase difference of 90 degrees (fourth polarized light 5). In this embodiment, the reflective polarizing element 14 only provides polarized light transmission with a phase difference of 0 degrees or 180 degrees, so the fourth polarized light 5 can penetrate the reflective polarizing element 14.

Please refer to FIG. 6, which is an exploded view of the short-distance optical system provided in the second embodiment of the present invention. In this embodiment, the first phase retarder 12 and the third phase retarder 17 are quarter-wave retarders, and the second phase retarder 13 is a half-wave retarder. Instructions. If the light 1 emitted by the display screen 10 is unpolarized light without a specific polarization state, a linear polarizer 18 and a third phase retarder 17 need to be added in sequence after the display screen 10. The polarized light passes through the linear polarizer 18 and is converted into linearly polarized light 1". Then, the linearly polarized light 1" undergoes the first phase delay through the third phase retarder 17 to increase the quarter-wave phase delay to Converted into circularly polarized light 1'. Next, the transmission state after the circularly polarized light 1'enters the partially reflecting and partially penetrating element 11 is the same as in the first and second embodiments described above. The circularly polarized light 1'is partially reflected and partially transmitted through the partially reflective and partially transmissive element 11. The transmitted circularly polarized light is successively passed through the first phase retarder 12 for a second phase delay, adding a quarter-wavelength phase delay, and converted into linearly polarized light (first polarized light 2). The linearly polarized light then passes through the second The phase retarder 13 performs the third phase delay, and its phase is delayed to a wavelength. Then, the linearly polarized light (second polarized light 3) is totally reflected by the reflective polarizing element 14 and returned to the second phase retarder 13 and the first phase retarder 12, and after the fourth and fifth phase delays, the transition It is circularly polarized light (third polarized light 4). The circularly polarized light penetrates the first phase retarder 12 and reaches the partially reflecting partially penetrating element 11, and then is partially reflected back by the partially reflecting partially penetrating element 11 back to the first phase retarder 12 and the second phase retarder 13, for the sixth After the second and seventh phase delays, it is converted into linearly polarized light (fourth polarized light 5). At this time, the phase difference of the linearly polarized light meets the penetration condition of the reflective polarizing element 14, and can penetrate the reflective polarizing element 14 and enter the lens, and then be introduced into at least one human eye 22.

In an implementation aspect of the third embodiment, the first phase retarder 12 and the third phase retarder 17 are quarter-wave retarders, and the second phase retarder 13 is a half-wave retarder , The linear polarizer 18 only provides 0-degree polarized light penetration, the partially reflective partial-transmissive element 11 is half-reflected and half-transmitted, and the reflective polarized element 14 only provides 90-degree or 270-degree phase difference polarized light penetration. In the state where the display screen 10 does not have a specific polarization state, the unpolarized light first passes through the linear polarizer 11 and then becomes linearly polarized light, and then undergoes the first phase delay through the third phase retarder 17 to convert the linearly polarized light into Circularly polarized light with a phase difference of 45 degrees. Then, as described above, after the second phase delay, the circularly polarized light is converted into linearly polarized light with a phase difference of 90 degrees (first polarized light 2). After the third phase delay, it is converted into linearly polarized light (second polarized light 3) with a phase difference of 180 degrees, and after the fourth and fifth phase delays, it is converted into a phase difference with a 315 degree phase difference Circularly polarized light (third polarized light 4), after the sixth and seventh phase delays, is converted into linearly polarized light (fourth polarized light 5) with a phase difference of 90 degrees, and can pass through the reflective type Polarizing element 14.

In another embodiment of the third embodiment, the first phase retarder 12 and the third phase retarder 17 are quarter-wave retarders, and the second phase retarder 13 is half-wave retarders The film and the linear polarizer 18 only provide 90-degree polarized light transmission, the partially-reflective and partially-transmissive element 11 is half-reflected and half-transmissive, and the reflective polarizer 14 only provides 0-degree or 180-degree phase difference polarized light transmission. Then, in the state where the display screen 10 does not have a specific polarization state, the unpolarized light first passes through the linear polarizer 18 and then becomes linearly polarized light, and then undergoes the first phase delay through the third phase retarder 17 to make the linearly polarized light It is converted into circularly polarized light with a phase difference of 135 degrees. Then, as described above, after the second phase delay, the circularly polarized light can be converted into linearly polarized light with a phase difference of 180 degrees (first polarized light 2). After the third phase delay, it can be converted into linearly polarized light (second polarized light 3) with a phase difference of 270 degrees, and after the fourth and fifth phase delays, it can be converted into a 45 degree position. The circularly polarized light (third polarized light 4), which undergoes the sixth and seventh phase delays, is converted into linearly polarized light (fourth polarized light 5) with a phase difference of 180 degrees and can penetrate Reflective polarizer 14.

All the elements in this creation are coaxial, and according to the polarization status of the display 10 of the head-mounted display, the third phase retarder 17 and the linear polarizer 18 of FIGS. 4 and 5 are used to increase or decrease the adjustment. In short, if the display screen 10 emits circularly polarized light, there is no need to provide the linear polarizer 18 and the third phase retarder 17; if the display screen 10 emits linearly polarized light, the third phase retarder 17 is required; If the display screen 10 emits unpolarized light without a specific polarization state, the linear polarizer 18 and the third phase retarder 17 need to be provided at the same time; or, the linear polarizer 18 and the third phase retarder 17 can also use a circular polarization To replace.

In summary, the short-distance optical system provided by this work uses a combination of quarter-wave phase retarders and half-wave phase retarders to extend the effective phase band of the phase retarder and improve the difference The phase delay conversion efficiency of the wavelength can reduce stray light, eliminate image chromatic aberration, and improve contrast to achieve the effect of improving image clarity. At the same time, by creating a partially penetrating partial reflection element, a first phase retarder, a second phase retarder, and a reflective polarizing element in front of the display screen, this invention uses multiple phase delays and reflections of light to achieve an optical path of approximate length, In this way, the distance between the display screen and the optical system is shortened to miniaturize the head-mounted display. And all the above-mentioned frameworks of this creation can be used for the function of myopia adjustment.

The above are only preferred embodiments of this creation, and are not intended to limit the scope of this creation. Therefore, any changes or modifications based on the characteristics and spirit described in the scope of this creative application should be included in the scope of the patent application for this creative.

1: light

1’: Circular polarization

1’’: Linearly polarized light

2: the first polarized light

3: second polarized light

4: third polarized light

5: fourth polarized light

10: Display

11: Partial reflection and partial penetration

12: First phase retarder

13: Second phase retarder

14: Reflective polarizing element

15: lens

16: Flat glass

17: Third phase retarder

18: linear polarizer

20: Optical module

22: Human eye

FIG. 1 is a schematic diagram of the optical path between the display screen of the head-mounted display and the human eye in the prior art. FIG. 2 is a schematic diagram of the short-distance optical system of the first embodiment. FIG. 3 is an exploded view of the short-distance optical system of the first embodiment of the creation. FIGS. 4A to 4C illustrate the optical path transmission process of the short-distance optical system of the first embodiment. FIG. 5 is an exploded view of the short-distance optical system of the second embodiment of the creation. Fig. 6 is an exploded view of the short-distance optical system of the third embodiment.

1: light

2: the first polarized light

3: second polarized light

4: third polarized light

5: fourth polarized light

10: Display

11: Partial reflection and partial penetration

12: First phase retarder

13: Second phase retarder

14: Reflective polarizing element

15: lens

22: Human eye

Claims (11)

A short-distance optical system is applied to a miniature head-mounted display with a display screen that outputs images and its light. The short-distance optical system includes: a part of the reflective part penetrating the element, which is set corresponding to the display screen, Receiving the light from the display screen and causing the light to partially penetrate and partially reflect; a first phase retarder is provided corresponding to the partially reflecting part penetrating element, and the receiving part penetrates the partially reflecting part penetrating element The light is phase-delayed to form a first polarized light; a second phase retarder is provided corresponding to the first phase retarder, receives the first polarized light, and performs phase delay to form a second polarized light; and A reflective polarizing element, corresponding to the second phase retarder, receives the second polarized light and performs total reflection, so that the second polarized light passes through the first phase retarder, the second phase retarder and the partial reflection After partially penetrating the element, it is reflected back to the reflective polarizing element and penetrates; wherein, when the first phase retarder is a half-wavelength phase retarder, the second phase retarder corresponds to a quarter-wavelength When the phase retarder is a quarter-wave retarder, the second phase retarder is a half-wave retarder. The short-distance optical system according to claim 1, further comprising a lens, which is disposed in any of the partially reflective partially penetrating element, the first phase retarder, the second phase retarder and the reflective polarizing element Either side of the one, the image output from the display screen into the eyes of at least one person. The short-distance optical system according to claim 2, wherein the lens is selected from a spherical lens, a non- Spherical lens, Fresnel lens, or multi-piece lens in any combination of the above. The short-distance optical system according to claim 3, wherein one or more sheets of flat glass may be included between the human eye and the lens, and one or more sheets of flat glass may be further included between the lens and the display screen. The short-distance optical system as described in claim 4, wherein the partially reflective partially penetrating element, the first phase retarder, the second phase retarder and the reflective polarizing element are thin-film materials or optically coated and coated with The form of cloth, coating or bonding is arranged on the flat glass. The short-distance optical system according to claim 1, wherein the light emitted from the display screen and entering the partially reflecting part penetrating element is circularly polarized light. The short-distance optical system as described in claim 1, wherein the light emitted from the display screen is linearly polarized light, and a third phase retarder is further provided between the display screen and the partially reflecting part penetrating element, so that the The linearly polarized light is phase-delayed via the third phase retarder, and then converted into circularly polarized light. The short-distance optical system as described in claim 1, wherein the light emitted from the display screen is unpolarized light, and a linear polarizer and a third phase are further provided between the display screen and the partially reflecting part penetrating element Retarder, the linear polarizer is arranged between the display screen and the third phase retarder, so that the non-polarized light passes through the linear polarizer to become linear polarized light, and the linear polarized light is then passed through the third phase retarder After the phase delay, it is converted into circularly polarized light. The short-distance optical system according to claim 7 or 8, wherein the third phase retarder is a quarter-wave retarder. The short-distance optical system according to claim 1, wherein the light emitted from the display screen is unpolarized light, and a circular polarizer is further provided between the display screen and the partially reflective part penetrating element to make the unpolarized light After passing through the circular polarizer, it is converted into circularly polarized light. The short-distance optical system according to claim 1, wherein the second polarized light reflected by the reflective polarizing element undergoes phase delay through the first phase retarder and the second phase retarder to form a third polarization Light, the third polarized light is partially reflected by the partial reflection part penetrating element, and then undergoes phase delay through the first phase retarder and the second phase retarder to form a fourth polarized light, the fourth polarized light The reflective polarizing element is penetrated, and the first polarized light, the second polarized light, and the fourth polarized light are linearly polarized light, and the third polarized light is circularly polarized light.

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