CN115220224A - Optical system of miniaturized head-mounted display - Google Patents

Optical system of miniaturized head-mounted display Download PDF

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Publication number
CN115220224A
CN115220224A CN202110418320.9A CN202110418320A CN115220224A CN 115220224 A CN115220224 A CN 115220224A CN 202110418320 A CN202110418320 A CN 202110418320A CN 115220224 A CN115220224 A CN 115220224A
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polarized light
optical
reflective
partially
optical system
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林柔慧
黄文昭
施富斌
游鸿文
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Dongguan Shuangying Optoelectronic Technology Co ltd
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Shuangying Technology Co ltd
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/017—Head mounted
    • G02B27/0172—Head mounted characterised by optical features
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/017—Head mounted
    • G02B2027/0178—Eyeglass type

Abstract

The invention provides an optical system of a miniaturized head-mounted display, which is characterized in that at least one phase delay element, a partial penetration partial reflection element and a reflection type polarization element are arranged behind an optical module and in front of a display screen, so that light rays emitted by the display screen are subjected to polarization, reflection and re-polarization for multiple times after incidence to obtain polarized light capable of penetrating through a last layer of reflection type polarization element, the polarized light is introduced into human eyes after passing through the reflection type polarization element and then enters the optical module, when at least one optical lens in the optical module is N,
Figure DDA0003026801610000011
wherein V dj And n j J is more than or equal to 1 and less than or equal to 3. All the optical elements are coaxial, and the shortest distance between the display screen and the final optical module is obtained under the condition of approximate optical path of light rays through multiple polarization and reflection, so that the purpose of miniaturization of the head-mounted display is achieved.

Description

Optical system of miniaturized head-mounted display
Technical Field
The present invention relates to a head-mounted display technology, and more particularly, to an optical system for a miniaturized head-mounted display.
Background
A Head-mounted display (Head-mounted display) is a device for displaying images and colors, 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 shows a virtual reality head-mounted display, an image projected by a display screen 10 enters an optical module 20 after passing through a light path with an optical path length d, and the optical module 20 guides the image into a human eye 22 of a user, and assuming that the optical path length d is 40mm, the length of the head-mounted display is inevitably greater than 40mm after the optical path length d is added with the optical module, an eye distance and a shell, which is slightly heavy for an eye mask and a helmet worn on the head, so that it is an important subject to reduce the thickness of the head-mounted display and facilitate the wearing and use of the user.
Therefore, the present invention provides an optical system of a miniaturized head-mounted display, which effectively solves the above problems, and the specific structure and the implementation thereof are described in detail below:
disclosure of Invention
The invention mainly aims to provide an optical system of a miniaturized head-mounted display, which is characterized in that optical elements such as a polarization element, a phase delay element, a partial reflection partial penetration element and the like are arranged between a display screen and an optical module of the head-mounted display, and the optical path with approximate length is achieved by utilizing the phase delay and multiple reflection of light rays so as to shorten the distance between the display screen and the optical module and miniaturize the head-mounted display.
Another objective of the present invention is to provide an optical system of a miniaturized head-mounted display, which is to arrange all optical elements on a same axis, and adjust the optical elements according to the polarization of the display, so as to increase the variability and flexibility of the optical system configuration while shortening the distance between the display and the optical module.
To achieve the above object, the present invention provides an optical system for miniaturized head-mounted display, comprising: a display screen for outputting images and emitting polarized light; a partially reflective partially transmissive element disposed in correspondence with the display screen to partially reflect the polarized light and partially transmit the partially reflective partially transmissive element; a second phase delay element corresponding to the partially reflective partially transmissive element for partially transmitting the polarization of the partially reflective partially transmissive elementThe light is subjected to phase retardation to become polarized light with a second polarization angle; a reflective polarization element, which is arranged corresponding to the second phase delay element, receives the polarized light of the second polarization angle, totally reflects the polarized light to the second phase delay element, and reflects the polarized light of the second polarization angle to the second phase delay element, after the polarized light of the second polarization angle passes through the second phase delay element and the partial reflection part transmission element, the polarized light of the second polarization angle is reflected to the second phase delay element and the reflective polarization element by the partial reflection part transmission element and is transmitted; and an optical module corresponding to the reflective polarizer and including at least one optical lens for receiving the polarized light penetrating through the reflective polarizer and guiding the polarized light to at least one eye, wherein when there are N optical lenses in the optical module,
Figure BDA0003026801590000021
wherein V dj Is Abbe number, n, of the optical lens j J is more than or equal to 1 and less than or equal to 3
According to an embodiment of the present invention, a curvature radius of an optical surface of the at least one optical lens of the optical module closest to the human eye is R eye ，
Figure BDA0003026801590000022
According to an embodiment of the present invention, a first lens is disposed closest to the human eye of the at least one optical lens, the first lens does not include a planar light-transmitting element and a polarizing film, and a curvature radius of an optical surface of the first lens facing the human eye is R 1 The radius of curvature of the other side is R 2 The maximum visible radius of the optical system is H,
Figure BDA0003026801590000023
according to an embodiment of the present invention, an optical surface of the at least one optical lens of the optical module closest to the human eye is a plane, a sphere, an aspheric surface, a fresnel surface, a free pattern or a partially concave portion convex.
According to an embodiment of the present invention, the optical module includes a linear polarizer disposed on a planar light-transmitting element or the optical lens.
According to an embodiment of the present invention, the linear polarizer is disposed on a last surface of the optical module, and the second phase retarder and the reflective polarizer are disposed on the linear polarizer.
According to an embodiment of the present invention, the second phase retarder and the reflective polarizer are disposed on a final surface of the optical lens in the optical module.
According to the embodiment of the invention, the thickness of the optical module is TTL, and 1 ≦ TTL ≦ 11.
According to the embodiment of the present invention, the focal length of the reflection surface of the partially reflective partially transmissive element is fs,122 ≦ fs ≦ infinity, and
Figure BDA0003026801590000031
f is the effective focal length of the optical system.
According to an embodiment of the present invention, when the at least one optical lens in the optical module satisfies
Figure BDA0003026801590000032
In this case, the at least one optical lens does not include a plate glass element and a polarizer.
According to an embodiment of the present invention, the reflective polarizing element is a polarizer and the second phase retardation element is a phase retardation plate.
According to an embodiment of the present invention, the reflective polarizing element is an element having a reflective polarizing function disposed in the optical module, or a mirror having a reflective polarizing function disposed in the optical module, and the second phase retardation element is a phase retardation plate.
According to an embodiment of the present invention, the reflective polarizing element is an element with reflective polarization function disposed in the optical module, or a mirror with reflective polarization function in the optical module, and the second phase retardation element is also disposed in the optical module, and is an element with phase retardation function before the reflective polarizing element, or a mirror with phase retardation function in the optical module.
According to an embodiment of the invention, the polarized light that is sent out of the display screen and enters the partially reflective partially transmissive element is circularly polarized light.
According to an embodiment of the present invention, the polarized light sent out by the display screen is linearly polarized light, and a first phase retardation element is further disposed between the display screen and the partially reflective transmissive element for performing a first phase retardation on the polarized light to obtain polarized light with a first polarization angle, and the linearly polarized light is converted into circularly polarized light after passing through the first phase retardation element.
According to an embodiment of the present invention, the reflective polarizer totally reflects the polarized light of the second polarization angle back to the second phase retardation element, so that the polarized light of the second polarization angle penetrates through the second phase retardation element and becomes polarized light of a third polarization angle, the polarized light of the third polarization angle penetrates through the second phase retardation element and becomes polarized light of a fourth polarization angle after being partially reflected back to the second phase retardation element by the partially reflective partially transmissive element, and the polarized light of the fourth polarization angle penetrates through the reflective polarizer.
In this case, the polarized light with the second polarization angle partially penetrates the second phase retardation element to be linearly polarized light, and the polarized light after being reflected by the reflective polarization element to penetrate the second phase retardation element to be circularly polarized light.
According to an embodiment of the present invention, the polarized light of the second polarization angle reflected by the reflective polarizer is linearly polarized light, and the polarized light of the fourth polarization angle transmitted by the reflective polarizer is linearly polarized light.
According to an embodiment of the present invention, the polarized light sent by the display panel is in an unspecified polarization state, a linear polarizer and a first phase retardation element are further disposed between the display panel and the partially reflective transmissive element, the linear polarizer is disposed between the display panel and the first phase retardation element, the polarized light provided by the display panel becomes linearly polarized light after passing through the linear polarizer, the first phase retardation element performs a first phase retardation on the linearly polarized light again to become polarized light of a first polarization angle, and the polarized light of the first polarization angle is converted into circularly polarized light.
According to an embodiment of the present invention, the optical module is a lens that is planar, spherical, aspherical, fresnel-surface, free-form or partially concave, and is a combination of one or more sheets of lenses.
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. 2A and fig. 2B are schematic diagrams illustrating an optical system of a miniaturized head-mounted display according to an embodiment of the present invention.
FIG. 3A is a schematic diagram of an optical system of a miniaturized head-mounted display according to another embodiment of the present invention.
Fig. 3B and 3C are schematic diagrams illustrating a conventional head-mounted display and an optical system of the head-mounted display in fig. 3A according to an embodiment of the invention.
FIG. 4 is a schematic diagram of an optical system of a miniaturized head-mounted display according to another embodiment of the present invention.
FIG. 5 is a schematic diagram of an optical system of a miniaturized head-mounted display according to another embodiment of the present invention.
Fig. 6 to 12 are schematic views illustrating an optical system of a miniaturized head-mounted display according to another embodiment of the present invention.
Description of reference numerals: 10-a display screen; 11-linear polarizer; 12-a first phase delay element; 14-partially reflective partially transmissive element; 16-a second phase delay element; 18-reflective polarizing element; 19-optic, first lens; 20-an optical module; 202-a planar light transmissive element; 204-linear polarizer; 205-a first lens; 206-a second lens; 208-a third lens; 22-human eye.
Detailed Description
The invention provides an optical system of a miniaturized head-mounted display, which is applied to the head-mounted display, in particular to a virtual reality system of the head-mounted display.
Referring to fig. 2A and 2B, which are schematic diagrams of an embodiment of an optical system of a miniaturized head-mounted display according to the present invention, including a display screen 10, a partially reflective transmissive element 14, a second phase retardation element 16, a reflective polarizer 18 and an optical module 20, referring to fig. 2A, in this embodiment, the display screen 10 outputs an image and emits polarized light, such as the polarized light 1 shown in the figure; the partially reflective and partially transmissive element 14 is disposed corresponding to the display screen 10, and reflects part of the incident polarized light 1 back to the display screen 10, and the rest penetrates through the partially reflective and partially transmissive element 14, in a preferred embodiment, the partially reflective and partially transmissive element 14 is half reflective and half transmissive; in addition, in this embodiment, the second phase retardation element 16 is an independent phase retardation plate, the reflective polarization element 18 is an independent polarizer, and the second phase retardation element 16 is disposed corresponding to the partially reflective partially transmissive element 14, and performs a second phase retardation on the polarized light 1 that has passed through the partially reflective partially transmissive element 14 to obtain a polarized light 2 with a second polarization angle; the reflective polarizer 18 is disposed corresponding to the second retardation element 16, and totally reflects the polarized light 2 back to the second retardation element 16, and the polarized light 2 is polarized once again after penetrating through the second retardation element 16 to become the polarized light 3 with a third polarization angle.
Referring to fig. 2B, the polarized light 3 with the third polarization angle penetrates the second phase retardation element 16 and reaches the partially reflective partially transmissive element 14, and then is partially reflected by the partially reflective partially transmissive element 14 back to the second phase retardation element 16 (the partially transmissive portion is energy loss), and is polarized after penetrating the second phase retardation element 16 to become the polarized light 4 with the fourth polarization angle, at this time, the fourth polarization angle of the polarized light 4 meets the transmission condition of the reflective polarizer 18, so the polarized light 4 can penetrate the reflective polarizer 18 and irradiate the corresponding optical module 20, and the optical module 20 guides the polarized light 4 into at least one human eye 22.
In a first embodiment, the light emitted from the display panel 10 is circularly polarized light with 45 degree polarization, so the first polarization angle is 45 degrees (i.e. the polarized light 1 is 45 degree polarized light), the second phase retardation element 16 is a 45 degree polarization element, the second polarization angle is 90 degrees (i.e. the polarized light 2 is 90 degree polarized light), the third polarization angle is 135 degrees (i.e. the polarized light 3 is 135 degree polarized light), and the fourth polarization angle is 180 degrees (i.e. the polarized light 4 is 180 degree polarized light). In this embodiment, the reflective polarizer 18 provides only 180 degree polarized light transmission, and thus the polarized light 4 may pass through the reflective polarizer 18.
In a second embodiment, the display panel 10 has different polarization states, the first polarization angle is 135 degrees (i.e. the polarized light 1 is 135 degrees polarized light), but the same is circularly polarized light, the second phase retardation element 16 is a 45-degree polarization element, the second polarization angle is 0 or 180 degrees (i.e. the polarized light 2 is 0 or 180 degrees polarized light), the third polarization angle is 45 degrees (i.e. the polarized light 3 is 45 degrees polarized light), and the fourth polarization angle is 90 degrees (i.e. the polarized light 4 is 90 degrees polarized light). In this embodiment, the reflective polarizer 18 provides only 90-degree polarized light transmission, and thus the polarized light 4 may pass through the reflective polarizer 18.
In the embodiment of fig. 2A and 2B, the polarized light 1 emitted by the display screen 10 is circularly polarized light; the polarized light 2 partially transmitted through the second phase retardation element 16 is linearly polarized light, while the polarized light 2 reflected by the reflective polarization element 18 is also linearly polarized light, but the polarized light 3 after passing through the second phase retardation element 16 becomes circularly polarized light. This polarized light 3 is originally circularly polarized light, but after being partially reflected by the second phase retardation element 16 and passing through the second phase retardation element 16 again, the polarized light 4 becomes linearly polarized light until the polarized light 4 passing through the reflective polarizer 18 remains linearly polarized light.
In the present invention, the focal length of the reflection surface of the partially reflective transmissive element 14 is fs,122 ≦ fs ≦ infinity, and
Figure BDA0003026801590000071
f is the effective focal length of the optical system.
In the present invention, the optical module 20 is a lens with a plane surface, a spherical surface, an aspherical surface, a fresnel surface, a free form or a partially concave convex surface, and is a combination of one or more pieces of lenses.
FIG. 3A is a schematic diagram of an optical system of a miniaturized head-mounted display according to another embodiment of the present invention. If the display screen 10 emits not circularly polarized light but linearly polarized light, as shown in fig. 3A, a first phase retardation element 12 needs to be added behind the display screen 10 to convert the polarized light emitted by the display screen 10 into circularly polarized light, and perform a first phase retardation to convert the circularly polarized light into polarized light 1 with a first polarization angle. After passing through the partially reflective partially transmissive element 14, the polarized light 1 is partially reflected back to the first phase retardation element 12, and the rest passes through the partially reflective partially transmissive element 14; the polarized light 1 partially transmitted through the partially reflective partially transmissive element 14 then passes through the second phase retardation element 16 and becomes polarized light 2 of the second polarization angle after the second phase retardation; the polarized light 2 is totally reflected by the reflective polarizing element 18 back to the second phase retardation element 16, and is polarized again to be the polarized light 3 of the third polarization angle after passing through the second phase retardation element 16. The polarized light 3 penetrates the second phase retardation element 16 and reaches the partially reflective partially transmissive element 14, and then is partially reflected by the partially reflective partially transmissive element 14 back to the second phase retardation element 16 (the partially transmitted portion is energy loss), and is polarized after penetrating the second phase retardation element 16, so as to become the polarized light 4 with a fourth polarization angle, at this time, the fourth polarization angle of the polarized light 4 conforms to the penetration condition of the reflective polarization element 18, so that the polarized light 4 can penetrate the reflective polarization element 18 and irradiate the corresponding optical module 20, and the optical module 20 guides the polarized light 4 into at least one human eye 22.
In a third embodiment, the polarized light emitted from the display screen 10 is linearly polarized at 0 degree, the first phase retardation element 12 is a 45-degree polarization element, so that the first polarization angle is 45 degrees (i.e. the polarized light 1 is 45-degree polarized light), the second phase retardation element 16 is a 45-degree polarization element, the second polarization angle is 90 degrees (i.e. the polarized light 2 is 90-degree polarized light), the third polarization angle is 135 degrees (i.e. the polarized light 3 is 135-degree polarized light), and the fourth polarization angle is 180 degrees (i.e. the polarized light 4 is 180-degree polarized light). In this embodiment, the reflective polarizer 18 provides only 180 degree polarized light transmission, and thus the polarized light 4 may pass through the reflective polarizer 18.
In a fourth embodiment, the display screen is 90-degree linearly polarized, the first retarder 12 is a 45-degree polarizer, the first polarization angle is 135 degrees (i.e., the polarized light 1 is 135 degrees), the second retarder 16 is also a 45-degree polarizer, the second polarization angle is 0 or 180 degrees (i.e., the polarized light 2 is 0 or 180 degrees), the third polarization angle is 45 degrees (i.e., the polarized light 3 is 45 degrees), and the fourth polarization angle is 90 degrees (i.e., the polarized light 4 is 90 degrees). In this embodiment, the reflective polarizer 18 provides only 90-degree polarized light transmission, and thus the polarized light 4 may pass through the reflective polarizer 18.
Fig. 3B and fig. 3C are schematic comparison diagrams of the optical systems of the conventional head-mounted display in fig. 1 and the head-mounted display in fig. 3A according to the present invention. The present invention can set the first phase retardation element 12 and the partially reflective and partially transmissive element 14 as a set, and the second phase retardation element 16 and the reflective and polarizing element 18 as a set, for example, the second phase retardation element 16 and the reflective and polarizing element 18 can be the same lens, for example, the reflective and polarizing element is disposed on the side of the second phase retardation element 16 close to the optical module 20 and is used as the reflective and polarizing element 18, or the same lens has the phase retardation and the reflective and polarizing functions by using special materials, and similarly, the first phase retardation element 12 and the partially reflective and partially transmissive element 14 can also be made on the same lens by selecting materials. As is well known, the thickness of the lens affects the refractive index and the optical path, and as the thickness of the lens is thicker, the refractive index is higher, and therefore the difference between the optical paths is higher, but the error is very small and still within the allowable range, so that fig. 3B and 3C can be said to have almost the same optical path d (total length of the dotted line in the figure), but the optical system of the present invention has a shorter back focal distance, and can shorten the back focal distance of the conventional head-mounted display to 0.3 to 0.7 times, so as to achieve the same clear image effect as the conventional head-mounted display.
FIG. 4 is a schematic diagram of an optical system of a miniaturized head-mounted display according to still another embodiment of the present invention. If the display panel 10 has no specific polarization state, as shown in fig. 4, a linear polarizer 11 needs to be added behind the display panel 10 and before the first phase retardation element 12 to convert the polarized light emitted from the display panel 10 into linear polarized light, the linear polarized light passes through the first phase retardation element 12 to become the polarized light 1 with the first polarization angle, and the polarized light 1 becomes circular polarized light. After passing through the partially reflective partially transmissive element 14, the polarized light 1 is partially reflected back to the first phase retardation element 12, and the rest passes through the partially reflective partially transmissive element 14; the polarized light 1 partially transmitted through the partially reflective partially transmissive element 14 then passes through the second phase retardation element 16 and becomes polarized light 2 of the second polarization angle after the second phase retardation; the polarized light 2 is totally reflected by the reflective polarizing element 18 back to the second phase retardation element 16, and is polarized again to be the polarized light 3 of the third polarization angle after passing through the second phase retardation element 16. The polarized light 3 penetrates the second phase retardation element 16 and reaches the partially reflective partially transmissive element 14, and then is partially reflected by the partially reflective partially transmissive element 14 back to the second phase retardation element 16 (the partially transmitted portion is energy loss), and is polarized after penetrating the second phase retardation element 16, so as to become the polarized light 4 with a fourth polarization angle, at this time, the fourth polarization angle of the polarized light 4 conforms to the penetration condition of the reflective polarization element 18, so that the polarized light 4 can penetrate the reflective polarization element 18 and irradiate the corresponding optical module 20, and the optical module 20 guides the polarized light 4 into at least one human eye 22.
In a fifth embodiment, if the first phase retardation element 12 and the second phase retardation element 16 are 45-degree polarization elements, the partially reflective partially transmissive element 14 is half-reflective and half-transmissive, and the reflective polarization element 18 only provides 180-degree polarization for transmission, in a state where the display panel 10 has no specific polarization state, the light is first changed into linearly polarized light after passing through the linear polarizer 11, then the 45-degree phase retardation is increased after passing through the first phase retardation element 12, so that the 45-degree polarized light 1 passing through the first phase retardation element 12 is changed into 45-degree polarized light 1, then the 45-degree polarized light 1 partially passes through the partially transmissive partially reflective element 14, and after passing through the second phase retardation element 16, the 90-degree phase-delayed polarized light 2 is polarized and is totally reflected on the reflective polarization element 18, the reflected light passes through the second phase retardation element 16 again, the phase of the polarized light 3 is adjusted from 90-degree retardation to 135-degree retardation, and then the light is partially transmitted through the partially reflective element 14 and reflected back to the second phase retardation element 16, and the light 3 is adjusted from 135-degree to 180-degree polarization state, and then enters the optical module 20.
In a sixth embodiment, the display panel 10 has no specific polarization state, but the linear polarizer 11 emits 90-degree linearly polarized light, the first phase retardation element 12 is a 45-degree polarization element, so that the first polarization angle is 135 degrees (i.e. the polarized light 1 is 135-degree polarized light), the second phase retardation element 16 is a 45-degree polarization element, the second polarization angle is 0 or 180 degrees (i.e. the polarized light 2 is 0 or 180-degree polarized light), the third polarization angle is 45 degrees (i.e. the polarized light 3 is 45-degree polarized light), and the fourth polarization angle is 90 degrees (i.e. the polarized light 4 is 90-degree polarized light). In this embodiment, the reflective polarizer 18 provides only 90 degree polarized light transmission, and thus the polarized light 4 may pass through the reflective polarizer 18.
All the elements of the present invention are coaxial, and are adjusted by increasing or decreasing the display screen 10 and the linear polarizer 11 of fig. 3A and fig. 4 according to the polarization state of the display screen of the head-mounted display, in short, if the display screen 10 emits circularly polarized light, the linear polarizer 11 and the first phase retardation element 12 are not required to be disposed; if the display screen 10 emits linearly polarized light, a first phase delay element 12 needs to be arranged; if the display panel 10 emits polarized light having no specific polarization state, the linear polarizer 11 and the first phase retarder 12 need to be provided at the same time.
For example, if the optical path from the display 10 to the optical module 20 in the embodiment of fig. 3A is a total optical path length d after the length of each reflection from the display 10 to the optical module 20 is approximately the same as the optical path length d from the display 10 to the optical module 20 in the prior art of fig. 1, but since the optical path from the display 10 to the optical module 20 in the embodiment of fig. 3A is a total of multiple reflections, the actual length from the display 10 to the optical module 20 is much shorter than the length from the display 10 to the optical module 20 in fig. 1, thereby achieving the purpose of shortening the length of the head mounted display.
The optical module 20 may further include at least one optical lens, for example, the reflective polarizer 18, or both the reflective polarizer 18 and the second phase retardation element 16 are disposed in the optical module, and if only the reflective polarizer is disposed in the optical module, it may be an element with reflective polarization function; if both are disposed in the optical module, as shown in fig. 5, the reflective polarizer 18 is a reflective polarizer, and the second phase retardation element 16 is a phase retardation element before the reflective polarizer 18. In this way, the back focal length can also be made shorter. In summary, the radius of curvature of the optical surface closest to the human eye 22 (e.g. the surface of the lens 19 close to the human eye 22 in fig. 5) of at least one optical lens of the optical module 20 is R eye ，
Figure BDA0003026801590000101
Furthermore, the optical surface of this lens 19 closest to the human eye 22 is planar, spherical, aspherical, fresnel-shaped, free-form or partially concave and convex.
In an embodiment of the present invention, a first lens (e.g. the lens 19 of fig. 5) is disposed in the optical module closest to the human eye 22, the first lens 19 does not include a planar light-transmitting element and a polarizing film, and a curvature radius of an optical surface of the first lens 19 facing the human eye is R 1 (equal to R of the upper section) eye ) And the radius of curvature of the other side is R 2 The maximum visible radius of the optical system of the present invention is H,
Figure BDA0003026801590000111
in addition, in another embodiment of the present invention, the optical module 20 includes a linear polarizer disposed on a planar transparent component or an optical lens. Referring to fig. 6, it is assumed that the optical module 20 includes a planar transparent element 202, and the linear polarizer 204 is disposed on the planar transparent element 202 by way of a lens or a coating. In addition, the linear polarizer may be further disposed on the rear-most side of the optical module 20, such as the linear polarizer 204 disposed on the rear-most lens in fig. 6, i.e. on the left side of the planar light-transmitting element 202, which is the rear-most side of the optical module 20.
In another embodiment, the second phase retarder 16 and the reflective polarizer 18 are disposed on the last side of the last optic of the optical module 20, or on the linear polarizer 204 on the last side of the optical module 20. Taking fig. 6 as an example, the positions of the second phase retarder 16 and the reflective polarizer 18 are changed to be on the linear polarizer 204.
FIG. 7 shows another embodiment of the present invention, in which N optical lenses are provided in the optical module 20
Figure BDA0003026801590000112
Wherein V dj Is Abbe number, n, of an optical lens j Is the refractive index of the optical lens. At this time, the optical lens in the optical module 20 does not include a plate glass and a polarizer. Taking fig. 7 as an example, the optical lens of the optical module 20 includes three lenses, from the position near the human eye 22 to the display screen 10, a first lens 205, a second lens 206 and a third lens 208 with refractive indexes n 1 、n 2 、n 3 Abbe number is V d1 、V d2 、V d3 The first, second and third lenses 205, 206 and 208 do not include a plane light-transmitting element and a polarizer, and
Figure BDA0003026801590000113
for example, although the first lens 205 in fig. 7 is planar, it may be a planar lens or a linear polarizer, rather than a planar transparent element or a polarizer.
Fig. 8 to 12 are schematic diagrams of optical systems of miniaturized head-mounted displays according to other embodiments of the present invention. The embodiment of fig. 8 sequentially includes a display screen 10, a partially reflective partially transmissive element 14, a second phase retardation element 16, a reflective polarization element 18, a planar light-transmitting element 202, a linear polarizer 204, and a first lens 205, where the first lens 205 is an optical module and is a fresnel lens. The embodiment of fig. 9 sequentially includes the display panel 10, the partially reflective partially transmissive element 14, the second phase retardation element 16, the reflective polarizing element 18, the planar light-transmissive element 202, the first lens 205, the planar light-transmissive element 202 and the linear polarizer 204, in which the first lens 205, the planar light-transmissive element 202 and the linear polarizer 204 are optical modules, and the first lens 205 is a fresnel lens. The embodiment of fig. 10 sequentially includes the display panel 10, the partially reflective partially transmissive element 14, the second phase retardation element 16, the reflective polarizer 18, the planar light transmissive element 202, the second lens 206, the linear polarizer 204, and the first lens 205, wherein the reflective polarizer 18 and the first lens 205 are all included in the optical module, and the first lens 205 is a spherical or aspheric lens, and the second lens 206 is a fresnel lens. The embodiment of fig. 11 sequentially includes the display screen 10, the partially reflective partially transmissive element 14, the second phase retardation element 16, the reflective polarizing element 18, the planar light transmissive element 202, the second lens 206, the first lens 205, the linear polarizer 204 and the planar light transmissive element 202, wherein the reflective polarizing element 18 and the planar light transmissive element 202 from the front of the human eye are all included in the optical module, and the first lens 205 is a spherical or aspheric lens, and the second lens 206 is a fresnel lens. The embodiment of fig. 12 sequentially includes a display 10, a partially reflective partially transmissive element 14, a second phase retardation element 16, a reflective polarizing element 18, a planar light transmissive element 202, a linear polarizer 204, a second lens 206, and a first lens 205, and the optical module of this embodiment includes the second lens 206 and the first lens 205, and the first lens 205 is a spherical lens or an aspheric lens, and the second lens 206 is a spherical lens or an aspheric lens. As can be seen from the embodiments of fig. 8 to 12, the optical module 20 of the present disclosure may include one or more optical lenses, and may be a combination of a plurality of lenses, such as a planar lens, a concave lens, a biconvex lens, and the like. If the first lens 205 closest to the human eye in the optical module 20 is a planar lens, a linear polarizer 204 may be further disposed thereon to further remove stray light.
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 the spirit described in the scope of the application of the present invention should be included in the protection scope of the present invention.

Claims (19)

1. An optical system for miniaturized head-mounted displays, comprising:
a display screen for outputting images and emitting polarized light;
a partially reflective partially transmissive element disposed in correspondence with the display screen to partially reflect the polarized light and partially transmit the partially reflective partially transmissive element;
a second phase delay element disposed corresponding to the partially reflective partially transmissive element, for receiving the polarized light partially transmitted through the partially reflective partially transmissive element, and performing phase delay to obtain polarized light of a second polarization angle;
a reflective polarization element, which is arranged corresponding to the second phase delay element, receives the polarized light of the second polarization angle, totally reflects the polarized light to the second phase delay element, and reflects the polarized light of the second polarization angle to the second phase delay element, after the polarized light of the second polarization angle passes through the second phase delay element and the partial reflection part transmission element, the polarized light of the second polarization angle is reflected to the second phase delay element and the reflective polarization element by the partial reflection part transmission element and is transmitted; and
a set of optical modules corresponding to the reflective polarizer, the optical modules including at least one optical lens for receiving the polarized light transmitted through the reflective polarizer and guiding the polarized light to at least one human eye,
wherein, when the number of the at least one optical lens in the optical module is N,
Figure FDA0003026801580000011
wherein V dj Is the Abbe number, n, of the at least one optical lens j J is more than or equal to 1 and less than or equal to 3 and is the refractive index of the at least one optical lens.
2. The optical system of claim 1, wherein a first of the at least one optical lens is closest to the human eyeA lens, wherein the first lens does not comprise a plane light-transmitting element and a membrane with a polarization function, and the curvature radius of the optical surface of the first lens facing the human eye is R 1 And the radius of curvature of the other side is R 2 The maximum visible radius of the optical system is H,
Figure FDA0003026801580000012
3. the optical system of claim 1, wherein the focal length of the reflective surface of the partially reflective transmissive element is fs,122 ≦ fs ≦ infinity, and
Figure FDA0003026801580000021
f is the effective focal length of the optical system.
4. The optical system of claim 1, wherein a radius of curvature of an optical surface of the at least one optical lens of the optical module closest to the human eye is R eye ，
Figure FDA0003026801580000022
5. The optical system of claim 1 or 4, wherein an optical surface of the at least one optical lens of the optical module closest to the human eye is a plane, a sphere, an aspheric surface, a Fresnel surface, a free pattern or a partially concave convex portion.
6. The optical system of claim 1, wherein the optical module comprises a linear polarizer disposed on a planar transparent element or the optical lens.
7. The optical system of claim 6, wherein the linear polarizer is disposed on the last side of the optical module, and the second phase retarder and the reflective polarizer are disposed on the linear polarizer.
8. The optical system of claim 1, wherein the second phase retarder and the reflective polarizer are disposed on a rear-most surface of the optical lens in the optical module.
9. The optical system of claim 1, wherein the thickness of the optical module is TTL,1 ≦ TTL ≦ 11.
10. The optical system of claim 1, wherein the at least one optical lens of the optical module satisfies the requirements
Figure FDA0003026801580000023
In this case, the at least one optical lens does not include a plate glass and a polarizer.
11. The optical system of claim 1, wherein the reflective polarizer is a polarizer and the second retarder is a phase retarder.
12. The optical system of claim 1, wherein the reflective polarizer is a reflective polarizer or a reflective mirror in the optical module, and the second phase retarder is a phase retarder.
13. The optical system of claim 1, wherein the reflective polarizer is a reflective polarizer or a reflective polarizer in the optical module, and the second retardation element is a phase retardation element before the reflective polarizer or a phase retardation mirror in the optical module.
14. The optical system of claim 1, wherein the polarized light emitted from the display screen and entering the partially reflective partially transmissive element is circularly polarized light.
15. The optical system of claim 1, wherein the polarized light emitted from the display panel is linearly polarized light, and a first phase retardation element is disposed between the display panel and the partially reflective transmissive element for performing a first phase retardation on the polarized light to obtain a polarized light with a first polarization angle, and the linearly polarized light is converted into circularly polarized light after passing through the first phase retardation element.
16. The optical system of claim 1, wherein a portion of the polarized light with the second polarization angle that penetrates the second phase retardation element is linearly polarized light, and a portion of the polarized light that penetrates the second phase retardation element after being reflected by the reflective polarizer element is circularly polarized light.
17. The optical system of claim 1, wherein the reflective polarizer totally reflects the polarized light of the second polarization angle back to the second phase retardation element, so that the polarized light of the second polarization angle penetrates through the second phase retardation element and becomes polarized light of a third polarization angle, the polarized light of the third polarization angle penetrates through the second phase retardation element and becomes polarized light of a fourth polarization angle after being partially reflected back to the second phase retardation element by the partially reflective partially transmissive element, and the polarized light of the fourth polarization angle penetrates through the reflective polarizer, wherein the polarized light of the second polarization angle reflected by the reflective polarizer is linearly polarized light, and the polarized light of the fourth polarization angle penetrated by the reflective polarizer is linearly polarized light.
18. The optical system of claim 1, wherein the polarized light emitted from the display panel is in an unspecified polarization state, a linear polarizer and a first retardation element are disposed between the display panel and the partially reflective partially transmissive element, the linear polarizer is disposed between the display panel and the first retardation element, the polarized light provided from the display panel is linearly polarized after passing through the linear polarizer, the first retardation element performs a first retardation on the linearly polarized light to obtain a polarized light with a first polarization angle, and the polarized light with the first polarization angle is converted into a circularly polarized light.
19. The optical system of claim 1, wherein the optical module is a lens with a flat surface, a spherical surface, an aspherical surface, a Fresnel surface, a free-form or a partially concave convex surface, and is a combination of one or more lenses.
CN202110418320.9A 2021-04-19 2021-04-19 Optical system of miniaturized head-mounted display Pending CN115220224A (en)

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