CN211603727U - Short-distance optical system - Google Patents
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- CN211603727U CN211603727U CN202020173172.XU CN202020173172U CN211603727U CN 211603727 U CN211603727 U CN 211603727U CN 202020173172 U CN202020173172 U CN 202020173172U CN 211603727 U CN211603727 U CN 211603727U
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Abstract
A short-distance optical system is applied to a micro head-mounted display, wherein a partial penetration partial reflection element, a first phase retarder, a second phase retarder and a reflection polarization element are sequentially arranged in front of a display screen to lead out light emitted by the display screen through multiple phase delays and reflections, so that the shortest distance between the display screen and the optical system is obtained under the condition of approximate optical path of the light, and the micro-shaping of the head-mounted display is achieved.
Description
Technical Field
The present invention relates to an optical system, and more particularly to a short-distance optical system applicable to a micro head-mounted display.
Background
Head-mounted displays (Head-mounted displays) are popular Virtual Reality (VR) products in recent years, and generally, in the form of an eye mask or a helmet, a display screen is close to eyes of a user, and a focal length is adjusted through an optical path to project a picture to the eyes in a short distance, so that a virtual image amplification effect is generated, and the experience of the scene is enhanced.
Fig. 1 is a schematic diagram of an optical system of a head-mounted display in a virtual reality, in which a display screen 10 projects an image, and the image passes through an optical path with an optical path length d and then enters an optical module 20, the optical module 20 is a single lens or a combination of a plurality of lenses for guiding the image into human eyes 22 of a user, assuming that the optical path length d is 40mm, and the length of the head-mounted display is the optical path length d plus the thickness, eye-fitting distance, and a shell of the optical module, which sum up to be slightly heavy for an eye mask and a helmet worn on the head, and causes a burden on the nose bridge, the top of the head, and the neck of the user, and therefore, the current technology aims to shorten the length of the optical system in the head-mounted display, so as to reduce the thickness of the head-mounted display, and facilitate wearing and use by the user.
In addition, in order to make the virtual image provided by the head-mounted display capable of being visually reproduced, a high-specification display quality must be obtained. Therefore, the present invention provides a short-distance optical system, which can shorten the distance of the optical system and further improve the definition of the displayed image, so as to effectively solve the above problems, and the specific structure and the implementation thereof will be described in detail later.
SUMMERY OF THE UTILITY MODEL
The primary objective of the present invention is to provide a short-distance optical system, which utilizes a first and a second phase retardation plates composed of a half-wavelength phase retardation plate and a quarter-wavelength phase retardation plate to expand the effective phase retardation band of the phase retardation plate, and improve the conversion efficiency of the phase retardation plate with respect to different wavelengths, so as to eliminate the image chromatic aberration and improve the image definition.
Another objective of the present invention is to provide a short-distance optical system, which is disposed with optical elements such as a partially reflective transmissive element, a first and a second phase retarders, and a reflective polarizer in front of a display screen of a head-mounted display, and uses multiple phase delays and reflections of light to achieve an optical path with an approximate length, so as to shorten the distance between the display screen and the optical system, thereby miniaturizing the head-mounted display.
To achieve the above object, the present invention provides a short-distance optical system for a micro head-mounted display having a display screen for outputting an image and light thereof, the short-distance optical system comprising: a partial reflection part transmission element which is arranged corresponding to the display screen and receives the light from the display screen and makes the light partially transmit and partially reflect; a first phase retardation plate disposed corresponding to the partially reflective partially transmissive element for receiving the light partially transmitted through the partially reflective partially transmissive element to perform phase retardation to form a first polarized light; the second phase retarder is arranged corresponding to the first phase retarder, receives the first polarized light and carries out phase retardation to form second polarized light; the reflective polarizing element is arranged corresponding to the second phase retarder, receives the second polarized light, partially reflects the second polarized light, and reflects the second polarized light reflected by the reflective polarizing element back to the reflective polarizing element and penetrates out after passing through the first phase retarder, the second phase retarder and the partially-reflected part penetrating element; when the first phase retarder is a half-wavelength phase retarder, the second phase retarder corresponds to a quarter-wavelength phase retarder, and when the first phase retarder is a quarter-wavelength phase retarder, the second phase retarder corresponds to a half-wavelength phase retarder.
According to the present invention, the display device further comprises a lens disposed on any one side of the partially reflective partially transmissive element, the first phase retarder, the second phase retarder and the reflective polarizer, for guiding the image outputted from the display screen to at least one human eye.
Further, the lens may be selected from a multi-piece lens including a spherical lens, an aspherical lens, a Fresnel lens, and combinations thereof.
Further, one to many sheets of flat glass may be included between the human eye and the lens, and one to many sheets of flat glass may be further included between the lens and the display screen.
Still further, the partially reflective partially transmissive element, the first phase retarder, the second phase retarder and the reflective polarizing element may be thin film materials or optically coated, and disposed on the plate glass in a 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 reflective partially transmissive element is circularly polarized light.
According to the present invention, the display device further comprises at least one linear polarizer, circular polarizer or phase retarder for adjusting the polarization state of the display panel, and the linear polarizer, the circular polarizer or the phase retarder is a film material or an optical coating and is disposed on the display panel or the partially reflective partially transmissive element in a coating, plating or bonding manner.
According to the embodiment of the present invention, the light emitted from the display panel is linearly polarized light, and a third phase retardation plate is further disposed between the display panel and the partially reflective transmissive element, so that the linearly polarized light is phase-delayed by the third phase retardation plate and then converted into circularly polarized light.
According to the embodiment of the present disclosure, the light emitted from the display panel is unpolarized light, a linear polarizer and a third phase retarder are further disposed between the display panel and the partially reflective transmissive element, the linear polarizer is disposed between the display panel and the third phase retarder, so that the unpolarized light is linearly polarized light after passing through the linear polarizer, and the linearly polarized light is phase-delayed by 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 present embodiment, the light emitted from the display panel is unpolarized light, and a circular polarizer is further disposed between the display panel and the partially reflective transmissive element, so that the unpolarized light is converted into circularly polarized light by the circular polarizer.
According to the embodiment of the present disclosure, the second polarized light reflected by the reflective polarizer is phase-delayed by the first phase retarder and the second phase retarder to form a third polarized light, and the third polarized light is partially reflected by the partially reflective transmissive element and then phase-delayed by the first phase retarder and the second phase retarder to form a fourth polarized light, and the fourth polarized light passes through the transflective polarizer; 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 purpose, technical content, features and effects achieved by the present invention will be more easily understood through the detailed description of the embodiments below.
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 a short-distance optical system according to a first embodiment of the present invention.
FIG. 3 is an exploded view of a short-range optical system according to a first embodiment of the present invention.
Fig. 4A to 4C show the optical path transmission process of the short-distance optical system according to the first embodiment of the present invention.
Fig. 5 is an exploded view of a short-distance optical system according to a second embodiment of the present invention.
FIG. 6 is an exploded view of a short-range optical system according to a third embodiment of the present invention.
List of reference numerals: 1-light; 1' -circularly polarized light; 1 "-linearly polarized light; 2-first polarized light; 3-second polarized light; 4-third polarized light; 5-fourth polarized light; 10-a display screen; 11-partially reflective partially transmissive element; 12-a first phase retarder; 13-a second phase retarder; 14-a reflective polarizing element; 15-a lens; 16-plate glass; 17-a third phase delay plate; 18-linear polarizer; 20-an optical module; 22-human eye.
Detailed Description
The creation provides a short-distance optical system, which is applied to a micro head-mounted display, and utilizes a plurality of optical elements to reflect light for multiple times, and phase delay sheets with different angles are matched in the optical elements, so that the definition of an image can be effectively improved, the chromatic aberration of the image can be eliminated, and the optical path with approximate length can be achieved by utilizing the phase delay and reflection of light for multiple times, thereby shortening the distance between a display device and the optical system and miniaturizing the head-mounted display.
Please refer to fig. 2 and fig. 3, which are a schematic diagram and an exploded view of a short-distance optical system according to a first embodiment of the present disclosure. As shown in fig. 2, the short-distance optical system of the present embodiment is disposed in the micro head-mounted display, and is located at the front end of the display screen 10, and a part of the reflective part transmission element 11, a first phase retardation plate 12, a second phase retardation plate 13, a reflective polarization element 14 and a lens 15 are disposed in sequence from the side adjacent to the display screen 10. In the present invention, the first phase retarder 12 and the second phase retarder 13 are a combination of a half-wavelength phase retarder and a quarter-wavelength phase retarder; specifically, when the first phase retarder 12 is set as a half-wave retarder, the second phase retarder 13 is correspondingly set as a quarter-wave retarder, and when the first phase retarder 12 is set as a quarter-wave retarder, the second phase retarder 13 is correspondingly set as a half-wave retarder.
In this embodiment, as shown in fig. 3, the display screen 10 outputs an image and emits a light 1, where the light 1 may be polarized light or unpolarized light, and when the light 1 is polarized light, the polarized light may be linearly polarized light, circularly polarized light, or other polarization states. The partial reflection partial transmission element 11 is arranged corresponding to the display screen 10, receives the incident light 1 and reflects part of the passed light 1 back to the display screen 10, and the rest penetrates the partial reflection partial transmission element 11; in a preferred embodiment, the partially reflective and partially transmissive element 11 is semi-reflective and semi-transmissive. The first phase retarder 12 is disposed corresponding to the partially reflective partially transmissive element 11, receives the light 1 transmitted through the partially reflective partially transmissive element 11, and performs a first phase retardation to form a 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 performs a second phase retardation to form a second polarized light 3. The reflective polarizing element 14 is disposed 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 polarizer 14 is subjected to third and fourth phase retardation by the second phase retarder 13 and the first phase retarder 12 to form third polarized light 4. After the third polarized light 4 is partially reflected by the partially reflective partially transmissive element 11, it sequentially passes through the first phase retarder 12 and the second phase retarder 13 to perform fifth and sixth phase retardation, so as to form the fourth polarized light 5, and at this time, the phase difference of the fourth polarized light 5 meets the transmission condition of the reflective polarizer 14, so that the reflective polarizer 14 can pass the fourth polarized light 5 after the sixth phase retardation. The lens 15 can be disposed on any side of any one of the above-mentioned optical systems to guide the image outputted from the display screen 10 into the human eye 22.
The partially transmissive partially reflective element 11, the first phase retarder 12, the second phase retarder 13 and the reflective polarizing element 14 provided in the present invention may be independent elements, as shown in fig. 2, and these optical elements may be thin film materials or optical coatings and disposed on one or more pieces of flat glass 16 in a coating, coating or bonding manner, and one or more pieces of flat glass 16 may be disposed between the human eye 22 and the lens 15 or between the lens 15 and the display screen 10. In the first embodiment, the partially transmissive partially reflective element 11 is a separate partially transmissive partially reflective element, and the first phase retarder 12, the second phase retarder 13 and the reflective polarizer 14 are disposed on the same plate glass 16 by means of pasting or coating.
The single lens 15 provided in the present invention can be a convex lens, as shown in fig. 2, the lens 15 can be disposed on any one side of the partially transmissive partially reflective element 11, the first phase retarder 12, the second phase retarder 13 and the reflective polarizing element 14, and is used for adjusting the focal length, regardless of being disposed between any two optical elements, to finally achieve the effect of shortening the optical system, while in the first embodiment, the lens 15 is disposed on the left side of the reflective polarizing element 14, close to the human eye 22. In addition, the lens 15 in the present invention can be a spherical lens, an aspherical lens, a Fresnel lens (Fresnel lens) or a multi-lens combination of the foregoing.
Since the first phase retarder 12 and the second phase retarder 13 are the combination of the quarter-wave phase retarder and the half-wave phase retarder, the light is reflected twice on the transmission path, and the light is phase-delayed six times, which is two and one quarter of the wavelength.
Further, taking the first phase retardation plate 12 and the second phase retardation plate 13 as a quarter-wave phase retardation plate and a half-wave phase retardation plate, respectively, as an example, the transmission process of the light 1 emitted from the display screen 10 in the above embodiment when entering the optical system is described in detail, please refer to fig. 4A to 4C. First, in fig. 4A, the display panel 10 of this embodiment outputs an image, and the emitted light 1 is operated in a polarization state of circularly polarized light, when the circularly polarized light is received by the partially reflective transmissive element 11, the partially reflective transmissive element 11 partially transmits the circularly polarized light to the first retardation plate 12, and partially reflects the circularly polarized light back to the display panel 10, and the circularly polarized light transmitted through the partially reflective transmissive element 1 is converted into linearly polarized light (the first polarized light 2) by increasing a quarter-wavelength retardation after passing through the first retardation plate 12, and the linearly polarized light is delayed by a phase difference to three-quarter-wavelength after passing through the second retardation plate 13, and then the linearly polarized light (the second polarized light 3) is totally reflected at the reflective polarizer 14.
Next, in fig. 4B, the linearly polarized light (second polarized light 3) reflected by the reflective polarizer 14 returns to the second phase retarder 13 and the first phase retarder 12 again, the quarter-wave phase retardation is added to form circularly polarized light (third polarized light 4), and then the circularly polarized light is partially transmitted and partially reflected by the partially transmissive partially reflective element 11.
Then, in fig. 4C, the circularly polarized light (third polarized light 4) partially reflected by the partially transmissive partially reflective element 11 passes through the first phase retarder 12 and the second phase retarder 13 in sequence, and is converted into linearly polarized light (fourth polarized light 5) after adding quarter-wave phase retardation. Then, the linearly polarized light reaches the reflective polarizer 14, the reflective polarizer 14 transmits 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 implementation of the above embodiment, the light 1 emitted from the display panel 10 is circularly polarized light with a phase difference of 45 degrees, and the first retardation film 12 is a quarter-wave retardation film, which can delay the polarization state of the circularly polarized light by 45 degrees, so that the first polarized light 2 is linearly polarized light with a phase difference of 90 degrees. The second phase retarder 13 is a half-wavelength phase retarder, which can re-delay the polarization state of the linearly polarized light by 90 degrees, such that the second polarized light 3 is linearly polarized light with 180 degrees phase difference, the third polarized light 4 is circularly polarized light with 315 degrees phase difference, and the fourth polarized light 5 is linearly polarized light with 90 degrees phase difference. In this embodiment, the reflective polarizer 14 only transmits polarized light with a phase difference of 90 degrees or 270 degrees, so the fourth polarized light 5 can pass through the reflective polarizer 14.
In another implementation of the above embodiment, the light 1 emitted from the display panel 10 is circularly polarized light with a phase difference of 135 degrees, and the first retardation film 12 is a quarter-wave retardation film, which can retard the polarization state of the circularly polarized light by 45 degrees, so that the first polarized light 2 is linearly polarized light with a phase difference of 180 degrees. The second phase retarder 13 is a half-wavelength phase retarder, which can re-delay the polarization state of the linearly polarized light by 90 degrees, such that the second polarized light 3 is the linearly polarized light with 270 degrees phase difference, the third polarized light 4 is the circularly polarized light with 45 degrees phase difference, and the fourth polarized light 5 is the linearly polarized light with 180 degrees phase difference. In this embodiment, the reflective polarizer 14 also only provides 180 ° out of phase polarized light transmission, so the fourth polarized light 5 can pass through the reflective polarizer 14.
In addition, the present invention can add one or more linear polarizers, circular polarizers or phase retarders between the display screen 10 and the partially reflective partially transmissive element 11 to adjust the polarization state of the display screen 10 according to the polarization condition of the display screen 10, and the linear polarizers, circular polarizers or phase retarders can be made of thin film material or optical coating, and can be disposed on the display screen 10 or the partially reflective partially transmissive element 11 by coating, coating or adhesion.
Fig. 5 is an exploded view of a short-distance optical system according to a second embodiment of the present disclosure. 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, for example. If the light 1 emitted from the display screen 10 is not circularly polarized light but linearly polarized light, a third phase retardation plate 17 needs to be added behind the display screen 10 to perform a first phase retardation on the linearly polarized light emitted from the display screen 10, and a quarter-wave phase retardation is added to convert the linearly polarized light into circularly polarized light 1'. Next, the transmission state of the circularly polarized light 1 'after entering the partially reflective partially transmissive element 11 is the same as that of the first embodiment described above, and the partially reflective partially transmissive element 11 partially reflects and partially transmits the circularly polarized light 1'. The transmitted circularly polarized light is subjected to secondary phase retardation by the first phase retardation plate 12, the quarter-wave phase retardation is added, and the circularly polarized light is converted into linearly polarized light (the first polarized light 2), and the linearly polarized light is subjected to third phase retardation by the second phase retardation plate 13, and the phase of the linearly polarized light is delayed to a wavelength. The linearly polarized light (second polarized light 3) is totally reflected by the reflective polarizer 14 again, returns to the second phase retarder 13 and the first phase retarder 12, is further subjected to fourth and fifth phase delays, and is converted into circularly polarized light (third polarized light 4). The circularly polarized light reaches the partially reflective partially transmissive element 11 after passing through the first phase retarder 12, and is partially reflected back to the first phase retarder 12 and the second phase retarder 13 by the partially reflective partially transmissive element 11, and is converted into linearly polarized light (fourth polarized light 5) after being phase-delayed for the sixth time and the seventh time. At this time, the phase difference of the linearly polarized light meets the penetrating condition of the reflective polarizer 14, and the linearly polarized light can penetrate through the reflective polarizer 14 and enter the lens, and then be guided into at least one human eye 22.
In an implementation manner of the second embodiment, the light 1 emitted from the display panel 10 is linearly polarized light with a phase difference of 0 degree, and the third phase retardation plate 17 is a quarter-wave phase retardation plate, so that after the first phase retardation, the polarization state of the linearly polarized light can be retarded by a phase difference of 45 degrees to form circularly polarized light with a phase difference of 45 degrees. The first retardation film 12 is a quarter-wave retardation film, and therefore, after the second phase retardation, the polarization state of the circularly polarized light is delayed by 45 degrees, and is converted into linearly polarized light (first polarized light 2) having a phase difference of 90 degrees. The second phase retarder 13 is a half-wave phase retarder, and therefore, after the third phase retardation, the polarization state of the linearly polarized light is again delayed by 90 degrees, and converted into the linearly polarized light having a phase difference of 180 degrees (the second polarized light 3), and after the fourth and fifth phase retardations, the polarization state of the linearly polarized light is converted into the circularly polarized light having a phase difference of 315 degrees (the third polarized light 4), and after the sixth and seventh phase retardations, the polarization state of the linearly polarized light is again converted into the linearly polarized light having a phase difference of 90 degrees (the fourth polarized light 5). In this embodiment, the reflective polarizer 14 only transmits polarized light with a phase difference of 90 degrees or 270 degrees, so the fourth polarized light 5 can pass through the reflective polarizer 14.
In another implementation manner of the second embodiment, the light 1 emitted from the display panel 10 is linearly polarized light with a phase difference of 90 degrees, and the third phase retardation plate 17 is a quarter-wave phase retardation plate, so that after the first phase retardation, the polarization state of the linearly polarized light can be retarded by 45 degrees to form circularly polarized light with a phase difference of 135 degrees. The first retardation film 12 is a quarter-wave retardation film, so that the polarization state of the circularly polarized light is delayed by 45 degrees after the second phase retardation, and is converted into linearly polarized light (first polarized light 2) having a phase difference of 180 degrees. The second phase retarder 13 is a half-wave phase retarder, and therefore, after the third phase retardation, the polarization state of the linearly polarized light is again delayed by 90 degrees, and converted into the linearly polarized light having a phase difference of 270 degrees (the second polarized light 3), and after the fourth and fifth phase retardations, the polarization state of the linearly polarized light is converted into the circularly polarized light having a phase difference of 45 degrees (the third polarized light 4), and after the sixth and seventh phase retardations, the polarization state of the linearly polarized light is again converted into the linearly polarized light having a phase difference of 90 degrees (the fourth polarized light 5). In this embodiment, the reflective polarizer 14 only transmits polarized light with a phase difference of 0 degree or 180 degrees, so the fourth polarized light 5 can transmit through the reflective polarizer 14.
Referring to fig. 6, an exploded view of a short-distance optical system according to a second embodiment of the present invention is shown. 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, for example. If the light 1 emitted from the display 10 is unpolarized light without specific polarization state, a linear polarizer 18 and a third phase retarder 17 are sequentially added behind the display 10, the unpolarized light emitted from the display 10 is first converted into linearly polarized light 1 "after passing through the linear polarizer 18, and then the linearly polarized light 1" is first phase-delayed by the third phase retarder 17 to be converted into circularly polarized light 1' by adding a quarter-wave phase delay. Next, the transmission state of the circularly polarized light 1' after entering the partially reflective partially transmissive element 11 is the same as that of the first and second embodiments described above. The circularly polarized light 1' is partially reflected and partially transmitted through the partially reflective partially transmissive element 11. The transmitted circularly polarized light is subjected to secondary phase retardation by the first phase retardation plate 12, the quarter-wave phase retardation is added, and the circularly polarized light is converted into linearly polarized light (the first polarized light 2), and the linearly polarized light is subjected to third phase retardation by the second phase retardation plate 13, and the phase of the linearly polarized light is delayed to a wavelength. The linearly polarized light (second polarized light 3) is totally reflected by the reflective polarizer 14 again, returns to the second phase retarder 13 and the first phase retarder 12, is further subjected to fourth and fifth phase delays, and is converted into circularly polarized light (third polarized light 4). The circularly polarized light reaches the partially reflective partially transmissive element 11 after passing through the first phase retarder 12, and is partially reflected back to the first phase retarder 12 and the second phase retarder 13 by the partially reflective partially transmissive element 11, and is converted into linearly polarized light (fourth polarized light 5) after being phase-delayed for the sixth time and the seventh time. At this time, the phase difference of the linearly polarized light meets the penetrating condition of the reflective polarizer 14, and the linearly polarized light can penetrate through the reflective polarizer 14 and enter the lens, and then be guided into at least one human eye 22.
In one implementation of the third embodiment, the first phase retarder 12 and the third phase retarder 17 are quarter-wave phase retarders, the second phase retarder 13 is a half-wave phase retarder, the linear polarizer 18 only provides 0-degree polarized light for transmission, the partially reflective transmissive element 11 only provides half-reflective half-transmissive light, and the reflective polarizer 14 only provides 90-degree or 270-degree polarized light for transmission, so that in a state where the display panel 10 has no specific polarization state, the non-polarized light first passes through the linear polarizer 11 and then becomes linearly polarized light, and then the first phase retardation is performed through the third phase retarder 17, so that the linearly polarized light is converted into circularly polarized light with a phase difference of 45 degrees. Then, after the second phase delay, the circularly polarized light is converted into linearly polarized light (first polarized light 2) having a phase difference of 90 degrees. After the third time phase delay, the light is converted into linearly polarized light with a phase difference of 180 degrees (the second polarized light 3), after the fourth time phase delay and the fifth time phase delay, the light is converted into circularly polarized light with a phase difference of 315 degrees (the third polarized light 4), after the sixth time phase delay and the seventh time phase delay, the light is converted into linearly polarized light with a phase difference of 90 degrees (the fourth polarized light 5), and the light can pass through the reflective polarizer 14.
In another implementation manner of the third embodiment, the first phase retarder 12 and the third phase retarder 17 are quarter-wave phase retarders, the second phase retarder 13 is a half-wave phase retarder, the linear polarizer 18 only provides 90-degree polarized light for transmission, the partially reflective transmissive element 11 only provides half-reflective half-transmissive, and the reflective polarizer 14 only provides 0-degree or 180-degree polarized light for transmission, so that in a state where the display panel 10 has no specific polarization state, the non-polarized light first passes through the linear polarizer 18 and then becomes linearly polarized light, and then the first phase retardation is performed through the third phase retarder 17, so that the linearly polarized light is converted into circularly polarized light with 135-degree phase difference. Then, after the second phase delay, the circularly polarized light can be converted into linearly polarized light (first polarized light 2) with a phase difference of 180 degrees. After the third time phase delay, the light can be converted into linearly polarized light with a phase difference of 270 degrees (the second polarized light 3), after the fourth time phase delay and the fifth time phase delay, the light can be converted into circularly polarized light with a phase difference of 45 degrees (the third polarized light 4), after the sixth time phase delay and the seventh time phase delay, the light can be converted into linearly polarized light with a phase difference of 180 degrees (the fourth polarized light 5), and the light can penetrate through the reflective polarizer 14.
All the components in the present invention are coaxial, and are adjusted by increasing or decreasing the third phase retarder 17 and the linear polarizer 18 in fig. 4 and fig. 5 according to the polarization state of the display panel 10 of the head-mounted display, in short, if the display panel 10 emits circularly polarized light, the linear polarizer 18 and the third phase retarder 17 are not needed; if the display screen 10 emits linearly polarized light, a third phase delay sheet 17 needs to be arranged; if the display panel 10 emits unpolarized light with no specific polarization state, the linear polarizer 18 and the third phase retarder 17 are required to be arranged at the same time; alternatively, the linear polarizer 18 and the third phase retarder 17 may be replaced by a circular polarizer.
In summary, the short-distance optical system provided by the present invention utilizes the combination of the quarter-wave phase retardation plate and the half-wave phase retardation plate to expand the effective phase retardation band of the phase retardation plate, thereby improving the phase retardation conversion efficiency of different wavelengths, thereby reducing stray light, eliminating image chromatic aberration, improving contrast, and achieving the effect of improving image definition. Meanwhile, the optical path with approximate length is achieved by arranging a partial transmission partial reflection element, a first phase delay sheet, a second phase delay sheet and a reflection type polarization element in front of the display screen and utilizing multiple phase delay and reflection of light rays, so that the distance between the display screen and the optical system is shortened, and the head-mounted display is miniaturized. Moreover, all the above-mentioned structures of the present creation can be used for the function of adjusting myopia.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Therefore, all the equivalent changes or modifications of the features and spirit described in the scope of the present application should be included in the scope of the claims of the present application.
Claims (11)
1. A short-distance optical system for use in a miniature head-mounted display having a display screen that outputs images and light therefrom, the short-distance optical system comprising:
a partial reflection partial transmission element, which is arranged corresponding to the display screen, receives the light from the display screen and makes the light partially transmit and partially reflect;
a first phase retardation plate disposed corresponding to the partially reflective partially transmissive element for receiving the light partially transmitted through the partially reflective partially transmissive element to perform phase retardation to form a first polarized light;
a second phase retarder, corresponding to the first phase retarder, for receiving the first polarized light and performing phase retardation to form a second polarized light; and
a reflective polarization element, which is arranged corresponding to the second phase retarder, receives the second polarized light and totally reflects the second polarized light, so that the second polarized light passes through the first phase retarder, the second phase retarder and the partially-reflected penetrating element, and then is reflected back to the reflective polarization element and penetrates through the reflective polarization element;
when the first phase retarder is a half-wavelength phase retarder, the second phase retarder corresponds to a quarter-wavelength phase retarder, and when the first phase retarder is a quarter-wavelength phase retarder, the second phase retarder corresponds to a half-wavelength phase retarder.
2. A short-range optical system as claimed in claim 1, further comprising a lens disposed on any one side of the partially reflective partially transmissive element, the first phase retarder, the second phase retarder and the reflective polarizing element to direct the image output by the display screen to at least one human eye.
3. A short-range optical system as claimed in claim 2 wherein the lens is selected from a spherical lens, an aspherical lens, a fresnel lens or a multi-lens combination thereof.
4. A short-range optical system as claimed in claim 3, wherein the space between the human eye and the lens comprises one to many sheets of flat glass, and the space between the lens and the display screen comprises one to many sheets of flat glass.
5. A short-range optical system as claimed in claim 4, wherein the partially reflective partially transmissive element, the first phase retarder, the second phase retarder and the reflective polarizing element are thin-film materials or optically coatings and are disposed on the plate glass in the form of coating, coating or adhesion.
6. A short-range optical system as claimed in claim 1, wherein the light transmitted from the display screen into the partially reflective partially transmissive element is circularly polarized light.
7. A short-distance optical system as claimed in claim 1, wherein the light emitted from the display panel is linearly polarized light, and a third phase retardation plate is disposed between the display panel and the partially reflective partially transmissive element, so that the linearly polarized light is phase-delayed by the third phase retardation plate and then converted into circularly polarized light.
8. A short-distance optical system as claimed in claim 1, wherein the light emitted from the display panel is unpolarized light, a linear polarizer and a third phase retarder are disposed between the display panel and the partially reflective partially transmissive element, the linear polarizer is disposed between the display panel and the third phase retarder, so that the unpolarized light is converted into linearly polarized light after passing through the linear polarizer, and the linearly polarized light is phase-delayed by the third phase retarder and then converted into circularly polarized light.
9. A short-range optical system as claimed in claim 7 or 8, wherein the third phase retarder is a quarter-wave retarder.
10. A short-range optical system as claimed in claim 1, wherein the light from the display screen is unpolarized light, and a circularly polarizing plate is disposed between the display screen and the partially reflective partially transmissive element to convert the unpolarized light into circularly polarized light.
11. A short-distance optical system as claimed in claim 1, wherein the second polarized light reflected by the reflective polarizer is phase-delayed by the first and second phase retarders to form a third polarized light, the third polarized light is partially reflected by the partially reflective partially transmissive element and is phase-delayed by the first and second phase retarders to form a fourth polarized light, the fourth polarized light is transmitted through the reflective polarizer, and the first, second and fourth polarized lights are linearly polarized lights and the third polarized light is circularly polarized light.
Priority Applications (1)
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| CN113267890A (en) * | 2020-02-14 | 2021-08-17 | 双莹科技股份有限公司 | Short-distance optical system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113267890A (en) * | 2020-02-14 | 2021-08-17 | 双莹科技股份有限公司 | Short-distance optical system |
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