CN110515208A - short distance optics - Google Patents

Abstract

The present invention provides a kind of short-range optical system, it sequentially includes a display screen, optical module and at least two lens groups comprising a reflective polarizer, first phase delay piece, a part of penetrating component reflecting element and an at least optical element, this at least two lens group is individually positioned in the either side for waiting elements in optical module.Display screen image output and after emitting beam, penetrate light portion through reflective polarizer, part is reflected, the light penetrated is after first phase delay piece carries out first time phase delay, pass through the reflecting element partial penetration of partial penetration part, part is then reflected back first phase delay piece and reflective polarizer carries out second and third time phase delay, then, light by third time phase delay carries out the 4th phase delay by optical element, then imports image in an at least human eye via lens group.

Description

short distance optics

technical field

The present invention relates to an optical system, in particular to a short-distance optical system applicable to a head-mounted display.

Background technique

Head-mounted display (Head-mounted display) is a device used to display images and colors, usually in the form of goggles or helmets, the display is close to the user's eyes, and the focus is adjusted through the optical path to project images to the eyes at close range , to produce the effect of virtual reality and increase the sense of presence of the wearer.

FIG. 1 is a schematic diagram of the optical system of a head-mounted display in virtual reality. The image projected from the display screen 10 enters the lens group 22 after passing through a section of optical path with an optical path of d. The lens group 22 is a single lens or multiple lenses. , used to guide the image into the user's eyes 24, assuming that the optical path d is 40mm, and the length of the head-mounted display is the sum of the optical path d plus the thickness of the lens group, eye distance, housing, etc. For the goggles and helmets worn on the head, it is a bit bulky, and it will cause a burden on the bridge of the nose, top of the head, and neck of the user and cannot be worn for a long time. Therefore, the current technology is devoted to shortening the length of the optical system in the head-mounted display. The thickness of the head-mounted display is reduced, which is convenient for the user to wear and use.

Therefore, the present invention proposes a short-distance optical system. In addition to shortening the distance of the optical system, it can also expand the field of view and effectively solve the above-mentioned problems. The specific structure and implementation methods will be described in detail later.

Contents of the invention

The main purpose of the present invention is to provide a short-distance optical system, which is provided with optical elements such as reflective polarizers, phase retarders, and partially penetrating partial reflective elements between the display screen and the lens group. Multiple reflections achieve similar or equal optical paths, thereby shortening the distance between the display screen and the lens group, which can eventually be used to miniaturize head-mounted displays.

Another object of the present invention is to provide a short-distance optical system, which arranges all optical elements on the same axis and adjusts them according to the polarization of the display screen, so as to shorten the distance between the display screen and the lens group. Increase the variability and flexibility of the optical system configuration.

Another object of the present invention is to provide a short-distance optical system, which can be applied to wide-angle lenses or wide-angle eyepieces on products such as head-mounted displays and game machines. Two lens groups are used to adjust the focal length, and the distance is short and the field of view is large. Good aberration correction can be achieved.

To achieve the above object, the present invention provides a short-distance optical system, including: a display screen, which outputs images and emits light; an optical module, including: a reflective polarizer, which is set corresponding to the display screen, so that the light in the light Penetration of vertically polarized light, reflection of horizontally polarized light; a first phase retarder, set corresponding to the reflective polarizer, receiving the light that penetrates the reflective polarizer, and performing phase delay for the first time; a part of the penetrating The partial reflective element is set corresponding to the first phase retarder, so that the first phase retarded light partially passes through the partial reflective element, and part of it is reflected back to the first phase retarder for the second and second phase delay. The third phase delay; at least one optical element is set corresponding to the part of the penetrating part of the reflection element, and the receiving part penetrates the part of the part of the penetrating part of the reflection element and passes through the second and third phase delays, and performs The fourth phase retardation; and at least two lens groups, which are respectively arranged on either side of at least two of the optical modules, to adjust the focal length and guide the image into at least one human eye.

According to an embodiment of the present invention, the optical element includes: a second phase retarder, which is set corresponding to the partly penetrating partly reflecting element, and the receiving part penetrates the partly penetrating partly reflecting element and passes through the second and third phase Delayed polarized light, and carry out the fourth phase delay; and a linear polarizer, corresponding to the second phase retarder setting, the linear polarizer is used to prevent the polarized light that has only undergone two phase delays from passing through and only allows it to pass through four The second phase retarded polarized light passes through.

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

According to an embodiment of the present invention, the light rays reflected back to the first phase retarder after passing through the partial reflective element pass through the first phase retarder to reach the reflection after the second phase delay of the first phase retarder. type polarizer, and complete the total reflection on the reflective polarizer, so that the light is reflected back to the first phase retarder and undergoes a third phase retardation, and then the light passes through the first phase retarder and the partially penetrated A partially reflective element reaches the second phase retarder.

According to the embodiment of the present invention, the first, second, third, and fourth phase delays are all increased by odd multiples of 1/4 wavelength, so that the light rays reaching the lens group are delayed by an integer multiple of 1 wavelength. .

According to an embodiment of the present invention, the light emitted from the display screen and entering the reflective polarizer is linearly polarized light. The linearly polarized light is transformed into left circularly polarized light or right circularly polarized light after passing through the first phase retarder.

According to an embodiment of the present invention, a linear polarizer is further included between the second phase retardation film and the human eye to prevent the light that has undergone only two phase delays from passing through and only allow the light that has undergone four phase delays to pass.

According to an embodiment of the present invention, at least one flat glass can be placed between the human eye and the lens group, at least one flat glass can also be placed between the lens group and the display screen, and the corresponding At least one of the optical modules can be made of a film material or an optical coating and placed on the flat glass in the form of coating, coating or bonding.

Description of drawings

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

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

3A to 3C are flowcharts of the steps of the short-distance optical system of the present invention.

4A to 4E are schematic diagrams of different configurations of two lens groups in the short-distance optical system of the present invention.

List of reference numerals: 10—display screen; 12—reflective polarizer; 14—first phase retarder; 16—partially transmissive and partially reflective element; 18—second phase retarder; 20—linear polarizer; 22— Lens group; 24-human eye; 26-flat glass; 30-first lens group; 32-second lens group.

Detailed ways

The present invention provides a short-distance optical system, which is applied to a head-mounted display, especially a virtual reality system of a head-mounted display. Since it is worn on the user's head, it is difficult to fix it if the volume is too large and too long The user's head will fall under the influence of gravity, which will cause a burden on the user's head and neck. Therefore, the smaller the size of the head-mounted display, the better, especially the length must be shortened. The purpose of the present invention is to Multiple lenses are used to reflect light multiple times, and the overall optical system is shortened under the same optical path length, so as to achieve the purpose of miniaturizing the head-mounted display.

Please refer to FIG. 2 , which is a schematic diagram of an embodiment of the short-distance optical system of the present invention, including a reflective polarizer 12 and a first phase retarder in sequence between a display screen 10 and at least the human eye 24 14. A part of the penetrating partial reflection element 16, a second phase retarder 18, a linear polarizer 20 and two lens groups 22, wherein the display screen 10 outputs images and emits light, which is polarized light or non-polarized light. In this embodiment, the polarized light is linearly polarized light. Further, the polarization direction of the linearly polarized light in this embodiment is perpendicular to the optical path; light, and partly transmit and partly reflect the polarized light, especially the reflective polarizer 12 adopted in the present invention includes two kinds of polarization directions, vertical and parallel to the optical path, the vertical axis is the transmission axis, and the horizontal axis is the reflection axis; the first The phase retarder 14 is set corresponding to the reflective polarizer 12, to receive the polarized light partially penetrating from the reflective polarizer 12, and to perform the first phase retardation; the partially penetrating partial reflective element 16 corresponds to the first phase retarder 14 is set to receive the light passing through the first phase retardation film 14 and partly reflect and partially penetrate the passed light; the second phase retardation film 18 is set corresponding to the partially penetrating partial reflection element 16, and receives the light partially penetrating the partial reflection element 16 light, and carry out phase retardation; linear polarizer 20 is arranged corresponding to the second phase retarder 18, and linear polarizer 20 is used for not passing through the polarized light of only two phase delays and only allowing the polarized light through four phase delays to pass through , the image is guided into the human eye 24 through the lens group 22 .

In particular, in the present invention, the fast and slow axes of the first phase retarder 14 and the transmission axis of the reflective polarizer 12 form an angle of 45 degrees, which can increase the phase delay of 1/4 wavelength.

In addition, at least two lens groups in the present invention are arranged on either side of at least two elements in the optical module. Taking the embodiment of FIG. 2 as an example, the two lens groups 22 are respectively arranged on the first phase retarder 14 sides. Each lens group can be a single lens or multiple lenses, and the lenses can be aspheric lenses, Fresnel lenses or a combination of multiple lenses.

Please refer to FIG. 3A to FIG. 3C for the specific steps in the present invention. First, in FIG. 3A, the display screen 10 outputs an image, and sends polarized light to the reflective polarizer 12, and the reflective polarizer 12 makes the polarized light partly penetrate. Part of the polarized light that reaches the first phase retarder 14 is reflected back to the display screen 10, and the partially transmitted polarized light that passes through the reflective polarizer 12 will undergo a phase delay for the first time after passing through the first phase retarder 14, and then reach the Partially penetrates the partial reflective element 16; then please refer to FIG. 3B, the polarized light through the first phase retardation is partially penetrated at the partially penetrated partial reflective element 16, and part is reflected back to the first phase retarder 14 for the second time Phase retardation, the polarized light that partially penetrates the partial reflection element 16 here is energy loss, and the polarized light that has undergone the first phase delay penetrates the first phase retardation film 14 and reaches the reflective polarizer 12; then please refer to 3C, the reflective polarizer 12 reflects the polarized light that has undergone the second phase retardation, reflects back to the first phase retarder 14, performs the third phase retardation, and then passes through the partially penetrating part reflective element 16, and partly passes through The transmitted polarized light (through the third phase retardation) reaches the second phase retarder 18, and undergoes the fourth phase retardation; then, the polarized light through the fourth phase retardation penetrates the second phase retarder 18, and is linearly polarized The linear polarizing film 20 is used for screening, and only the polarized light that has been retarded four times passes through the linear polarizing film 20 and is guided into at least one human eye 24 by the lens group 22 .

Since the first phase retardation film 14 and the second phase retardation film 18 in the present invention are both odd multiples of 1/4 wavelength, they are retarded by an integer multiple of 1 wavelength after four phase delays.

The linearly polarized light will be transformed into circularly polarized light after passing through the first phase retarder 14 , including left circularly polarized light and right circularly polarized light. However, when part of the circularly polarized light is reflected back to the first phase retarder 14 by partly penetrating the partial reflection element 16, it will become linearly polarized light again, although it will pass through the first phase retarder 14 and be converted into circularly polarized light , however, after passing through the second phase retarder 18, it will still be converted into linearly polarized light.

Figure 4A to Figure 4E are embodiments of multiple different configuration methods of two lens groups, these two lens groups are respectively the first lens group 30 and the second lens group 32, but this embodiment does not limit the lens group in the present invention The configuration method is as long as a lens group is arranged on any side of at least one of the reflective polarizer 12, the first phase retarder 14, the partially penetrating partial reflection element 16, the second phase retarder 18 and the linear polarizer 20, A total of at least two sets of lens groups for focusing are included in the scope of this application.

To further illustrate, the materials of optical components such as the reflective polarizer 12, the first phase retarder 14, the partially transmissive partial reflection element 16, the second phase retarder 18 and the linear polarizer 20 can be thin film materials or optical coatings, etc. Place on at least one flat glass or lens in the form of coating, coating or bonding. The spectacle lens of reflective polarizing function or the optical material that is the film form is pasted on the lens, therefore, the present invention can set reflective polarizer 12 and first retarder 14 as a whole, partly penetrates part reflective element 16 and the second The phase retarder 18 is set as one. For example, as shown in FIG. 4A, the reflective polarizer 12 and the first phase retarder 14 are the same lens group 32 (the second lens group 32 is a single lens in this embodiment) For example, a reflective polarizing film is provided on the side of the first phase retarder 14 close to the display screen 10 or a special material is used to achieve the functions of phase retardation and reflective polarization on the same lens, while on the left side of the first lens group 30, according to A partially transmitting and partially reflecting element 16 (in this embodiment, a partially transmitting and partially reflecting film), a second phase retarder 18 , a linear polarizing plate 20 and a flat glass 26 are provided in sequence. In other words, in the embodiment of FIG. 4A , the first lens group 30 is arranged between the first phase retarder 14 and the partially penetrating part-reflective element 16, and the second lens group is arranged between the reflective polarizer 12 and the first phase retarder 16. Between retarder 14. The concrete data of this embodiment is as follows table one:

Table I

A, B, C, D, E, etc. in the above table are parameters in the aspheric formula, and the aspheric formula is

Wherein C=1/R, R is the radius of curvature. In addition, f in the table is the effective focal length of the optical system, ω is the half field angle of the optical system, H is the radius of the visible range of the display screen, f1 and f2 are the effective focal lengths of the first and second lens groups respectively, and Nd is Refractive index (Refractive index), Vd is Abbe number (Abbe number) or dispersion coefficient (V-number).

Figure 4B shows another embodiment, the reflective polarizer 12 is arranged on the display screen 10, the first phase retarder 14 is arranged on the left side of the reflective polarizer 12, and the part of the penetrating part of the reflective element 16 can also pass through the coating Or the material is chosen to be made on the second lens group 32 , and the second phase retarder 18 and the linear polarizer 20 are respectively on the right side of the first lens group 30 . The concrete data of this embodiment are as following table two:

Table II

Fig. 4C, Fig. 4D and Fig. 4E are other three configurations of the first lens group 30 and the second lens group 32, because the first lens group 30 and the second lens group 32 can be a single lens or a combination of multiple lenses , and can be concave lens, convex lens, etc., and the concave-convex direction can also be changed, so there will be many different combinations.

In the embodiment of FIG. 4C , the second lens group 32 is disposed between the first phase retarder 14 and the partially transmissive partial reflective element 16, and the partially transmissive partial reflective element 16 of this embodiment is disposed on the second lens group 32 The coating on the left side, while the reflective polarizer 12 is arranged on the right side of the second lens group 32 and the right side of the first phase retarder; Between sheet 18, the concrete data of this embodiment is as following table three:

Table three

In the embodiment of FIG. 4D , the first lens group 30 and the second lens group 32 are all arranged between the first phase retarder 14 and the partially penetrating partial reflection element 16, wherein the reflective polarizer 12 and the first phase retarder 14 are all arranged on the right side of the second lens group 32, the reflective polarizer 12 is arranged on the right side of the first phase retarder 14, and partly penetrates the partial reflection element 16, the second phase retarder 18, the linear polarizer 20 And the plate glass 26 are all arranged on the left side of the first lens group 30 , wherein the partially penetrating partial reflection element 16 is a coating film arranged on the first lens group 30 . The concrete data of this embodiment are as following table four:

Table four

In the embodiment of Fig. 4E, it can be seen from the position of total reflection that this configuration sets the reflective polarizer 12 on the left side of the display screen 10, and the first lens group 30 and the second lens group 32 are both arranged at the first phase Between the retarder 14 and the partially transmissive partial reflective element 16 , on the left side of the first lens group 30 are the partially transparent partial reflective element 16 , the second phase retarder 18 , the linear polarizer 20 and the plate glass 26 . The specific data of this embodiment are as follows table five:

Table five

To further illustrate, in the present invention, the second phase retarder 18 and the linear polarizer 20 can be integrated. For example, as shown in FIG. 4D, the phase retarder 18 and the linear polarizer 20 are on the same side of the same lens 30. Equivalent to the function of circular polarizer.

The present invention can achieve the effects of larger viewing angle, shorter system distance and good aberration correction. Please refer to FIG. 4A, wherein the first lens group 30 is L1, its effective focal length is f1, and the second lens group 32 is L2, its effective focal length is f2, F is the effective focal length of the optical system, ω is the half-field angle of the optical system, H is the radius of the visible range of the display screen, R1~R4 are the curvature radii of the positions shown in the figure, and E is the eye (aperture) The distance to the center of the nearest optical element surface, TTL is the total length of the optical system, the following formula can be obtained:

The above formulas (1), (4), and (5) can achieve good aberration correction, while the formulas (2), (3), and (6) can achieve the advantages of larger viewing angle and shorter system distance (thinner and thinner) .

The present invention utilizes the principle of polarization to perform internal refraction and reflection of the optical path in the optical system to shorten the distance between the display screen and the human eye. Taking Figures 4A to 4E as examples, the polarized light in the figure is sent from the display screen 10 to the human eye. The optical path of the optical element in front of the human eye 24 has undergone multiple reflections. Assuming that in the embodiment of FIG. 4A to FIG. The optical path is d, which is almost the same as the optical path d from the display screen 10 to the lens group 22 in the prior art of FIG. The sum of multiple reflections is obtained, so the length from the display screen 10 to the human eye will actually be much smaller than the length from the display screen 10 to the human eye 24 in FIG. 1 , so as to achieve the purpose of shortening the length of the optical system.

To sum up, in the short-distance optical system provided by the present invention, an optical module including a plurality of optical elements is sequentially placed behind the display screen and in front of the human eye, and the length of the optical system is shortened by using multiple reflections of light. And use the phase delay film to carry out four phase delays, so that when the polarization state of the polarized light finally reaches the human eye, it is delayed by an integer multiple of a wavelength from the polarization state emitted from the display screen at the beginning. The present invention utilizes the design of the double-lens group to achieve a good aberration correction effect. It is suitable for wide-angle lenses or wide-angle eyepieces. display) can achieve the purpose of thinness and miniaturization.

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

Claims (16)

1. A short-distance optical system, characterized in that, comprising: A display screen that outputs images and emits light; An optical module, comprising: A reflective polarizer, set corresponding to the display screen, so that the light partly penetrates and partly reflects; A first phase retarder, set corresponding to the reflective polarizer, receiving part of the light that penetrates the reflective polarizer, and performing the first phase retardation; A part of the penetrating part of the reflective element is set corresponding to the first phase retarder, so that the first phase retarded light partially penetrates the part of the penetrating part of the reflective element, and part of it is reflected back to the first phase retarder for further processing. Second and third phase delays; At least one optical element is arranged corresponding to the partially penetrating partial reflective element, receiving the light that partially penetrates the partially penetrating partial reflective element and undergoes the second and third phase delays, and performs a fourth phase delay, and not passing light that has been phase-delayed only twice but only passing light that has been delayed four times; and At least two lens groups are respectively arranged on either side of at least one of the optical modules to adjust the focal length and guide the image into at least one human eye. 2. The short-distance optical system according to claim 1, characterized in that at least one plate glass can be placed between the human eye and the lens group, and at least one flat plate can also be placed between the lens group and the display screen Glass, and at least one of the corresponding optical modules is arranged on the flat glass, and its material can be a thin film material or an optical coating, which is placed on the flat glass in the form of coating, coating or bonding. 3. The short-distance optical system according to claim 1, wherein the optical element comprises: A second phase retarder, set corresponding to the partially penetrating partial reflective element, receiving the polarized light that partially penetrates the partially penetrating partial reflective element and undergoes the second and third phase delays, and performs the fourth phase delay phase delay; and A linear polarizer is set corresponding to the second phase retarder, and the linear polarizer is used to prevent the polarized light that has undergone only two phase delays from passing through and only allow the polarized light that has undergone four phase delays to pass through. 4. The short-distance optical system according to claim 1, wherein the optical element is a circular polarizer. 5. The short-distance optical system according to claim 3, characterized in that, the light rays reflected back to the first phase retarder by the part of the penetrating part of the reflective element pass through the second phase delay of the first phase retarder After that, it reaches the reflective polarizer through the first phase retarder, and completes the reflection on the reflective polarizer, so that the light is reflected back to the first phase retarder and undergoes a third phase retardation, and then the light passes through The first phase retarder and the part of the penetrating partially reflective element reach the second phase retarder. 6. The short-distance optical system according to claim 1, characterized in that, the first, second, third, and fourth phase delays all increase the phase delay of an odd multiple of 1/4 wavelength, so that the The light rays of the human eye are delayed by an integer multiple of one wavelength. 7. The short-distance optical system according to claim 1, wherein the light emitted from the display screen and entering the reflective polarizer can be linearly polarized light, circularly polarized light or other polarization states, and the Between the display screen and the reflective polarizer, a linear polarizer, a circular polarizer or a phase retarder can be added to adjust the polarization state of the display screen according to the polarization of the display screen. The number is not limited to one and the material can be The thin film material or optical coating is placed on the display screen or the reflective polarizer in the form of coating, coating or bonding. 8. The short-distance optical system according to claim 7, wherein the linearly polarized light is converted into left circularly polarized light or right circularly polarized light after passing through the first phase retarder. 9. The short-distance optical system according to claim 1, wherein the at least two lens groups comprise a first lens group and a second lens group, the effective focal length of the first lens group is f1, the The effective focal length of the second lens group is f2, and the effective focal length of the optical system is F, 10. The short-distance optical system according to claim 1, wherein the at least two lens groups comprise a first lens group and a second lens group, the viewing range radius of the display screen is H, the The total length of the optical system is TTL, 11. The short-distance optical system according to claim 1, wherein the at least two lens groups comprise a first lens group and a second lens group, the viewing range radius of the display screen is H, the The total length of the optical system is TTL, the distance from the eye to the center of the surface of the closest of the optical modules is E, 12. The short-distance optical system according to claim 1, wherein the at least two lens groups comprise a first lens group and a second lens group, the effective focal length of the optical system is F, and the part passes through The radius of curvature of the partially reflective element is R1, the radius of curvature of the second phase retarder is R2, 13. The short-distance optical system according to claim 1, wherein the at least two lens groups comprise a first lens group and a second lens group, the effective focal length of the optical system is F, and the first The radius of curvature of the phase retarder is R3, and the radius of curvature of the reflective polarizer is R4, 14. The short-distance optical system according to claim 1, wherein the at least two lens groups comprise a first lens group and a second lens group, the effective focal length of the optical system is F, and the optical system The half field angle is ω, the total length of the optical system is TTL, 15. The short-distance optical system according to claim 1, wherein the lens group comprises a single lens or multiple lenses. 16. The short-distance optical system according to claim 1, wherein the lens group can be an aspherical lens, a Fresnel lens or a combination of multiple lenses.