TWM591624U - Short distance optical system - Google Patents

Abstract

This creation provides a short-distance optical system, which in turn includes a display screen, an optical module including a reflective polarizer, a first phase retarder, a part of a partially reflective element and at least one optical element, and at least two For the lens group, the at least two lens groups are placed on either side of the elements in the optical module. After the screen outputs the image and emits light, the light is partially penetrated and partially reflected by the reflective polarizer. After the first phase delay by the first phase retarder, the transmitted light is partially penetrated by the partially penetrating partial reflection element Partially reflected back to the first phase retarder and reflective polarizer for the second and third phase retardation, and then, the light after the third phase retardation passes through the optical element for the fourth phase retardation, and then passes through the lens The group imports the image into the eyes of at least one person.

Description

Short-distance optical system

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

Head-mounted display (Head-mounted display) is a device used to display images and colors, usually in the form of an eye mask or helmet, close the display to the user's eyes, and adjust the focal length through the optical path to project the eyes at close range The picture produces a virtual reality effect and increases the wearer's sense of presence.

Fig. 1 is a schematic diagram of an optical system of a virtual reality head-mounted display. The display screen 10 projects an image, and enters the lens group 22 after passing through an optical path with an optical path of d. The lens group 22 is a single lens or multiple lenses The combination of lenses is used to introduce the image into the human eye 24, assuming the optical path d is 40mm, and the length of the head-mounted display is the optical path d plus the thickness of the lens group, suitable eye distance, housing, etc. The sum is slightly bulky for the eye masks and helmets worn on the head, and it will cause a burden on the bridge of the nose, the top of the head, and the neck of the user and cannot be worn for a long time. Therefore, the current technical department is committed to shortening the length of the optical system in the head-mounted display to The thickness of the head-mounted display is reduced, which is convenient for users to wear and use.

Therefore, this creation 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 these problems. The specific architecture and implementation will be described in detail later.

The main purpose of this creation is to provide a short-distance optical system, which is equipped with optical elements such as reflective polarizers, phase retarders, partially penetrating partial reflection elements, etc. between the display screen and the lens group. The secondary reflection reaches an optical path of approximately or the same length, so as to shorten the distance between the display screen and the lens group, and finally can be used to miniaturize the head-mounted display.

Another purpose of this creation is to provide a short-distance optical system, which is to set all the optical elements on the coaxial and adjust according to the polarization of the display screen, in order to shorten the distance between the display screen and the lens group Increase the variability and flexibility of the optical system configuration.

Another purpose of this creation 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, game consoles, etc., using two lens groups for focal length adjustment, short distance, large field of view, can Achieve good aberration correction.

To achieve the above purpose, the author provides a short-distance optical system, including: a display screen to output images and emit light; an optical module, including: a reflective polarizer, corresponding to the display screen set, so that the light Vertical polarized light penetration, horizontal polarized light reflection; a first phase retarder, corresponding to the reflective polarizer, receives the light penetrating the reflective polarizer, and performs the first phase delay; part of the transmissive part The reflecting element is set corresponding to the first phase retarder, so that the light beam delayed by the first phase partially penetrates the partial reflecting element, and partially reflects back to the first phase retarder for the second and third times Sub-phase delay; at least one optical element, corresponding to the partially penetrating partial reflecting element, the receiving part penetrating the partially penetrating partial reflecting element and passing through the second and third phase retarded rays, and the fourth Phase delay; and at least two lens groups, which are respectively disposed on at least either side of the optical module to adjust the focal length and direct the image into at least one person's eyes.

According to an embodiment of the present invention, the optical element includes: a second phase retarder, corresponding to the partially penetrating partial reflective element, and the receiving part penetrating the partially penetrating partial reflective element and passing through the second and third phases Delay the polarized light and perform the fourth phase delay; and a linear polarizer, corresponding to the second phase retarder, the linear polarizer is used to prevent polarized light that has undergone only two phase delays from passing through and only passing through four The polarized light of the second phase delay passes.

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

According to an embodiment of the present invention, the light partially reflected by the partial reflection element and returned to the first phase retarder passes the second phase delay of the first phase retarder, and then reaches the reflection through the first phase retarder Type polarizer and complete total reflection on the reflective polarizer to allow the light to be reflected back to the first phase retarder and perform a third phase delay, then the light passes through the first phase retarder and the part penetrates The partially reflective element reaches the second phase retarder.

According to the embodiment of the present invention, the first, second, third, and fourth phase delays all increase the phase delay by an odd multiple of 1/4 wavelength, so that the light reaching the lens group is delayed by a whole number of wavelengths. Times.

According to the 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 can be converted into left circularly polarized light or right circularly polarized light after passing through the first phase retarder.

According to the embodiment of the present invention, a linear polarizer is further included between the second phase retarder and the human eye to prevent light passing through only two phase delays from passing and only passing light passing through four phase delays .

According to the 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 a corresponding For at least one of the optical modules, the material may be a thin film material or an optical coating, etc., which is placed on the flat glass in the form of coating, coating, or bonding.

This creation provides a short-distance optical system, which is applied to the head-mounted display, especially the virtual reality system of the head-mounted display. Because it is worn on the user's head, if it is too large and too long, it is difficult to fix it to the user The head will fall under the influence of gravity, and it will also burden the user's head and neck. Therefore, the smaller the size of the head-mounted display, the better, especially the length must be shortened, and the purpose of this creation is to use the plural The lens reflects the light multiple times and shortens the overall optical system under the same length of light path to achieve the purpose of miniaturizing the head-mounted display.

Please refer to FIG. 2, which is a schematic diagram of an embodiment of creating a short-distance optical system, including a reflective polarizer 12 and a first phase delay in sequence between a display screen 10 and at least the human eye 24 Sheet 14, a part of 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 an image and emits light, which is polarized light or unpolarized 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; the reflective polarizer 12 is provided corresponding to the display screen 10, and the receiving display screen 10 The emitted polarized light partially transmits and reflects the polarized light. In particular, the reflective polarizer 12 used in this work contains two polarization directions perpendicular and parallel to the optical path. The vertical axis is the transmission axis and the horizontal axis is the reflection. Axis; the first phase retarder 14 is corresponding to the reflective polarizer 12 is provided to receive the polarized light partially reflected from the reflective polarizer 12, and the first phase delay; partially penetrated part of the reflective element 16 is The first phase retarder 14 should be arranged to receive the light passing through the first phase retarder 14 and partially reflect and partially penetrate the light passing through; the second phase retarder 18 is arranged corresponding to the partially penetrating partial reflection element 16 and the receiving part The light passing through the partial reflection element 16 is phase-delayed; the linear polarizer 20 is arranged corresponding to the second phase retarder 18, and the linear polarizer 20 is used to prevent polarized light that has undergone only two phase delays from passing and only passing through The polarized light with four phase delays passes through, and the image is introduced into the human eye 24 through the lens group 22.

In particular, in this composition, the fast and slow axes of the first phase retarder 14 and the transmission axis of the reflective polarizer 12 are at a 45 degree angle, which can increase the phase retardation of 1/4 wavelength.

In addition, at least two lens groups in this creation are not provided 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 provided on the first phase retarder 14 On both sides. Each lens group can be a single lens or multiple lenses, and the lens can be an aspheric lens, a Fresnel lens or a combination of multiple lenses.

Please refer to Figures 3A to 3C for the specific steps in this creation. First, in Figure 3A, the display screen 10 outputs images and emits polarized light to the reflective polarizer 12, which reflects the polarized light. Partially penetrates to the first phase retarder 14 and partly reflects back to the display screen 10, and the partially transmitted polarized light penetrating the reflective polarizer 12 passes the first phase retarder 14 and undergoes the first phase delay , And then to the partially penetrating partial reflection element 16; then please refer to FIG. 3B, the polarized light after the first phase delay partially penetrates at the partially penetrating partial reflection element 16, and partially reflects back to the first phase retarder 14 Perform the second phase delay, where the polarized light partially penetrating the reflective element 16 is an energy loss, and the polarized light after the first phase delay penetrates the first phase retarder 14 and reaches the reflective polarizer 12; Next, referring again to FIG. 3C, the reflective polarizer 12 reflects the polarized light after the second phase delay, reflects it back to the first phase retarder 14, performs the third phase delay, and then passes through the partially reflective component 16. The partially polarized light (after the third phase delay) reaches the second phase retarder 18 and undergoes the fourth phase delay; then, the polarized light after the fourth phase delay penetrates the second phase delay The film 18 is screened by the linear polarizer 20, and only the polarized light after four phase delays passes through the linear polarizer 20 and is guided by the lens group 22 into at least one human eye 24.

Since the first phase retarder 14 and the second phase retarder 18 are both odd-numbered phase delays of 1/4 wavelength in this creation, after a total of four phase delays, a total of 1 wavelength is delayed.

After passing through the first phase retarder 14, the linearly polarized light will be converted into circularly polarized light, including left circularly polarized light or right circularly polarized light. However, when part of the circularly polarized light is reflected back to the first phase retarder 14 by the partially penetrating reflective 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 again. However, after passing through the second phase retarder 18, it will still be converted into linearly polarized light.

FIGS. 4A to 4E are examples of different configurations of the two lens groups. The two lens groups are the first lens group 30 and the second lens group 32, respectively, but this embodiment does not limit the lens group in this creation. The configuration method is as long as the lens group is provided on any side of at least one of the reflective polarizer 12, the first phase retarder 14, the partially penetrating partial reflective element 16, the second phase retarder 18, and the linear polarizer 20 A total of at least two lens groups for focusing are included in the scope of this case.

表一 To further explain, the material of the optical elements such as the reflective polarizer 12, the first phase retarder 14, the partially penetrating partial reflective element 16, the second phase retarder 18, and the linear polarizer 20 may be a thin film material or an optical coating, etc. It is placed on at least one flat glass or lens in the form of coating, coating, bonding, etc. For example, the reflective polarizer 12 and the partially penetrating partial reflective element 16 may be coated on the lens, or may have reflection on their own The polarized lens or optical material in the form of a film is attached to the lens. Therefore, in this creation, the reflective polarizer 12 and the first phase retarder 14 can be integrated into one body, partially penetrating the partially reflective element 16 and the second phase The retarder 18 is integrated, 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 in this embodiment is a single lens) For example, a reflective polarizing film is provided on the side of the first phase retarder 14 near the display screen 10 or a special material is used to achieve the function of phase retardation and reflective polarizing of the same lens, and on the left side of the first lens group 30, in order Partially penetrating partial reflection elements 16 (partially penetrating partial reflection films in this embodiment), a second phase retarder 18, a linear polarizer 20, and a flat glass 26 are provided. In other words, in the embodiment of FIG. 4A, the first lens group 30 is disposed between the first phase retarder 14 and the partially penetrating partial reflection element 16, and the second lens group is disposed between the reflective polarizer 12 and the first Between the phase retarders 14. The specific data of this embodiment is as follows in Table 1:

Table I

，其中C=1/R，R為曲率半徑。此外，表中f為光學系統之有效焦距，𝜔為光學系統之半視場角，H為顯示屏的可視範圍半徑，f1及f2分別為第一、第二透鏡組的有效焦距，Nd為折射率(Refractive index)，Vd為阿貝數(Abbe number)或色散係數(V-number)。 A, B, C, D, E, etc. in the above table are the parameters in the aspheric formula, and the aspheric formula is

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

表二 FIG. 4B shows another embodiment. The reflective polarizer 12 is provided on the display screen 10, and the first phase retarder 14 is provided on the left side of the reflective polarizer 12. Partially penetrating and partially reflecting elements 16 can also pass through the coating Or the material selection is 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 specific data of this embodiment is shown in Table 2 below:

Table II

FIGS. 4C, 4D and 4E are three other arrangements of the first lens group 30 and the second lens group 32. Since the first lens group 30 and the second lens group 32 can be a single lens or multiple lenses The combination can be a concave lens, a convex lens, etc., and the direction of the concave and convex can also be changed, so a variety of different combinations will occur.

表三 In the embodiment of FIG. 4C, the second lens group 32 is disposed between the first phase retarder 14 and the partially penetrating partial reflective element 16, and the partially penetrating partially reflective element 16 of this embodiment is provided in the second lens group 32 is coated on the left side, and the reflective polarizer 12 is provided on the right side of the second lens group 32 and on the right side of the first phase retarder; the first lens group 30 is provided on the partially penetrating partial reflection element 16 and the second phase retarder 18 Between, the specific data of this embodiment is as follows in Table 3:

Table 3

表四 In the embodiment of FIG. 4D, the first lens group 30 and the second lens group 32 are both disposed between the first phase retarder 14 and the partially penetrating partial reflection element 16, wherein the reflective polarizer 12 and the first phase retarder The plates 14 are all provided on the right side of the second lens group 32, the reflective polarizer 12 is provided on the right side of the first phase retarder 14, and the partial reflection element 16, the second phase retarder 18, the linear polarizer 20 and The plate glasses 26 are all disposed on the left side of the first lens group 30, and the partially-transmissive partial reflection element 16 is a coating film disposed on the first lens group 30. The specific data of this embodiment is shown in Table 4 below:

Table 4

表五 In the embodiment shown in FIG. 4E, it can be seen from the position of total reflection that this configuration is that the reflective polarizer 12 is disposed on the left side of the display screen 10, and the first lens group 30 and the second lens group 32 are both disposed on the first Between the phase retarder 14 and the partially penetrating partial reflection element 16, on the left side of the first lens group 30 are partially penetrating partially reflecting element 16, second phase retarder 18, linear polarizer 20 and plate glass 26 in sequence. The specific data of this embodiment is shown in Table 5 below:

Table 5

To further explain, in this creation, 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. Can be equivalent to the function of a circular polarizer.

(1)

(2)

(3)

(4)

(5)

(6) 上述公式(1)、(4)、(5)可達到良好的像差校正，而公式(2)、(3)、(6)則可達到較大視角、系統距離縮短(輕薄化)之優點。 This creation can achieve the effects of larger viewing angle, shortened system distance and good aberration correction, please refer to Figure 4A, where the first lens group 30 is L ₁ , its effective focal length is f ₁ , and the second lens group 32 is L ₂ , The effective focal length is f ₂ , F is the effective focal length of the optical system, 𝜔 is the half angle of view of the optical system, H is the radius of the visible range of the display screen, R ₁ ~ R ₄ are the radius of curvature of the position shown in the figure, E is the distance from the eye (aperture) to the center of the closest optical element surface, TTL is the total length of the optical system, and the following formula can be obtained:

(1)

(2)

(3)

(4)

(5)

(6) The above formulas (1), (4), and (5) can achieve good aberration correction, while formulas (2), (3), and (6) can achieve a larger viewing angle and shorten the system distance (thin and thin) ) Advantages.

This creation uses the principle of polarization to internally reflect the optical path in the optical system to achieve the effect of shortening the distance between the display screen and the human eye. Taking FIGS. 4A to 4E as examples, the polarized light is emitted from the display screen 10 The optical path of the optical element back to the front of the human eye 24 undergoes multiple reflections, assuming the length of each reflection of light from the display screen 10 to the optical element in front of the human eye 24 in the embodiments of FIGS. 4A to 4E The optical path after summing 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. 1, but since in the embodiments of FIGS. 4A to 4E, the display screen 10 to The optical path of the human eye is obtained by summing up multiple reflections, so the length from the display screen 10 to the human eye is actually much shorter than the length from the display screen 10 to the human eye 24 in FIG. The purpose of the length.

To sum up, the short-distance optical system provided by this creation is to place an optical module containing a plurality of optical elements in sequence behind the display screen and in front of the human eye, using multiple reflections of light to achieve the purpose of shortening the length of the optical system And, the phase retarder is used for phase delay four times, so that the polarization state of the polarized light is delayed by an integer multiple of one wavelength from the polarization state emitted from the display screen when it finally reaches the human eye. This design uses the design of the double lens group to achieve good aberration correction. It is suitable for wide-angle lenses or wide-angle eyepieces. The angle of view can reach more than 50 degrees. And because the length of the optical system is shortened, products that use optical systems (such as head-mounted (Display) can achieve the purpose of thin, light and miniaturized.

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

10: Display 12: reflective polarizer 14: First phase retarder 16: Partially penetrating and partially reflecting elements 18: Second phase retarder 20: linear polarizer 22: lens group 24: human eye 26: Flat glass 30: First lens group 32: Second lens group

FIG. 1 is a schematic diagram of the optical path between the display screen of the head-mounted display and the human eye in the prior art. . FIG. 2 is a schematic diagram of an embodiment of creating a short-distance optical system. Figures 3A to 3C are flowcharts of the steps for creating a short-distance optical system. Figures 4A to 4E are schematic diagrams of different configurations of two lens groups in a short-distance optical system.

10: Display

12: reflective polarizer

14: First phase retarder

16: Partially penetrating and partially reflecting elements

18: Second phase retarder

20: linear polarizer

22: lens group

24: human eye

Claims (16)

A short-distance optical system, including: A display screen, output images and emit light; An optical module, including: A reflective polarizer, corresponding to the display screen, so that the light partially penetrates and partially reflects; A first phase retardation plate, corresponding to the reflective polarizer, receiving the light passing through the reflective polarizer, and performing the first phase delay; Part of the penetrating partial reflection element is set corresponding to the first phase retarder, so that the light beam delayed by the first phase partially penetrates the partial penetrating partial reflection element, and partly reflects back to the first phase retarder for the first Second and third phase delay; At least one optical element, corresponding to the partially penetrating partial reflecting element, the receiving part penetrating the partially penetrating partial reflecting element and passing through the light rays of the second and third phase delays, and performing the fourth phase delay, and Let light that has undergone only two phase delays not pass through but only light that has undergone four phase delays; and At least two lens groups are respectively disposed on either side of at least one of the optical modules to adjust the focal length and introduce images into at least one person's eyes. The short-distance optical system according to claim 1, wherein at least one flat glass can be placed between the human eye and the lens group, and at least one flat glass can be placed between the lens group and the display screen, and the At least one of the corresponding optical modules is provided on the plate glass, and its material may be a thin film material or an optical coating film, etc., which is placed on the plate glass in the form of coating, coating, or bonding. The short-distance optical system according to claim 1, wherein the optical element includes: A second phase retarder, corresponding to the partially penetrating partial reflection element, the receiving part penetrating the partially penetrating partial reflection element and passing through the polarized light of the second and third phase delays, and performing the fourth phase Delay; and A linear polarizer corresponds to the setting of the second phase retarder. The linear polarizer is used to prevent polarized light that has undergone only two phase delays from passing and only allows polarized light that has undergone four phase delays to pass. The short-distance optical system according to claim 1, wherein the optical element is a circular polarizer. The short-distance optical system according to claim 3, wherein the light partially reflected by the partial reflection element and returned to the first phase retarder passes through the first phase retarder after the second phase delay A phase retarder reaches the reflective polarizer and completes the reflection on the reflective polarizer, allowing the light to reflect back to the first phase retarder and perform a third phase delay, then the light passes through the first phase delay The plate and the part penetrate the partial reflection element to reach the second phase retarder. The short-distance optical system according to claim 1, wherein the first, second, third, and fourth phase delays all increase the phase delay by an odd multiple of 1/4 wavelength, so that the light reaching the human eye A total of multiples of one wavelength are delayed. The short-distance optical system according to claim 1, wherein the light emitted from the display screen and entering the reflective polarizer may be linearly polarized light, circularly polarized light or other polarization states, and the display screen and the reflective type Linear polarizers, circular polarizers or phase retarders can be added to adjust the polarization state of the display according to the polarization situation of the display between polarizers. The number of polarizers is not limited to one and the material can be thin film material or optical coating, etc. It is placed on the display screen or the reflective polarizer in the form of coating, coating or bonding. 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. The short-distance optical system according to claim 1, wherein the at least two lens groups include a first lens group and a second lens group, the effective focal length of the first lens group is f ₁ , and the second lens group The effective focal length is f ₂ , the effective focal length of the optical system is F,

. The short-distance optical system according to claim 1, wherein the at least two lens groups include a first lens group and a second lens group, the visible range radius of the display screen is H, and the total length of the optical system is TTL,

. The short-distance optical system according to claim 1, wherein the at least two lens groups include a first lens group and a second lens group, the radius of the visible range of the display screen is H, and the total length of the optical system is TTL, The distance from the eye to the center of the nearest surface of the optical module is E,

. The short-distance optical system according to claim 1, wherein the at least two lens groups include a first lens group and a second lens group, the effective focal length of the optical system is F, and the curvature of the partially penetrating partial reflection element The radius is R ₁ , and the radius of curvature of the second phase retarder is R ₂ ,

. The short-distance optical system according to claim 1, wherein the at least two lens groups include a first lens group and a second lens group, the effective focal length of the optical system is F, and the radius of curvature of the first phase retarder Is R ₃ , the radius of curvature of the reflective polarizer is R ₄ ,

. The short-distance optical system according to claim 1, wherein the at least two lens groups include a first lens group and a second lens group, the effective focal length of the optical system is F, and the half angle of view of the optical system is 𝜔 , The total length of the optical system is TTL,

. The short-distance optical system according to claim 1, wherein the lens group includes a single lens or a complex lens. The short-distance optical system according to claim 1, wherein the lens group may be an aspheric lens, a Fresnel lens, or a combination of multiple lenses.

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