CN213934432U

CN213934432U - Optical module and VR equipment

Info

Publication number: CN213934432U
Application number: CN202120269119.4U
Authority: CN
Inventors: 王豪
Original assignee: Nanchang Virtual Reality Institute Co Ltd
Current assignee: Nanchang Virtual Reality Institute Co Ltd
Priority date: 2021-01-29
Filing date: 2021-01-29
Publication date: 2021-08-10
Anticipated expiration: 2031-01-29

Abstract

The optical module sequentially comprises a first polaroid, a first lens, a first phase retarder, a second lens and a display unit, wherein the first polaroid is a curved surface, the surface between the adjacent surfaces of the first polaroid and the first lens can be attached, a partial transmission partial reflector is arranged on the optical surface between the second lens and the display unit, and the display unit is used for providing an incident polarized light source of the optical module. This optical module compares in traditional design and has improved the design degree of freedom, for reducing the aberration provides the optics basis, under the prerequisite of guaranteeing the image quality, has further optimized thickness, the weight of VR module, realizes ultra-thin folding light path.

Description

Optical module and VR equipment

Technical Field

The utility model relates to a VR technical field especially relates to an optical module and VR equipment.

Background

In VR (Virtual Reality) products, the optical module is the most core display component thereof, including a VR display screen (display) and a VR lens. The Display is used as an imaging element of the optical module, and a virtual image is presented in human eyes through the VR lens.

In order to provide a good user experience, the current optical module is developed toward a light and thin direction. However, in order to achieve a better field angle, a better eye movement range, a high-quality imaging effect, a small-sized ultra-thin structure, and the like, the current optical module needs to be further optimized.

The current ultra-thin VR optical module mostly uses a folded optical path technology, and as shown in fig. 1, a polarizer 10 and a phase retarder (not shown) are generally attached to a plano-convex lens 20 on a side close to the eye, so as to implement a reflection and transmission function in the optical path. In the prior art, the polarizer 10 is generally plated on the lens surface by a plating process during the manufacturing process, while the plating of the polarizer on the plano-convex lens has one less degree of freedom in design, and if the degree of freedom is increased, a flat plate must be introduced to plate the polarizer thereon or add the lens, resulting in an increase in the overall volume.

SUMMERY OF THE UTILITY MODEL

In view of the above, it is necessary to provide an optical module and VR equipment to increase the degree of freedom of the module structure design on the premise of ensuring the image quality, which is beneficial to further optimizing the thickness and weight of the VR module, so as to realize an ultra-thin folded optical path module with better effect.

An optical module is characterized by sequentially comprising a first polaroid, a first lens, a first phase retarder, a second lens and a display unit, wherein the first polaroid is a curved surface, the adjacent surfaces of the first polaroid and the first lens can be jointed in a surface mode, a partial transmission partial reflector is arranged on the optical surface of the second lens adjacent to the display unit, and the display unit is used for providing an incident polarized light source of the optical module.

Further, in the optical module, the first polarizer is a curved reflective polarizing film, and is disposed on an optical surface of the first lens close to the first polarizer.

Further, in the optical module, an optical surface of the first lens, which is close to the first polarizer, is a concave surface.

Further, in the optical module, the first phase retarder may be respectively surface-mounted to adjacent surfaces of the first lens and the second lens.

The utility model discloses in, the battery of lens is the core component who influences the enlarged effect of optical image, and this first lens and second lens form the battery of lens can be the laminating together also can be the separation. The first lens and the second lens can be made of glass materials or glass-plastic mixed materials.

Further, above-mentioned optical module, wherein, optical module satisfies the conditional expression:

5.9F≤|f1|≤53F；

4.6F≤|fs1|≤53F；

|fs2|≥2.6F；

-38mm≤R1≤-15mm；

wherein F1 is a focal length of the first lens, fs1 is a focal length of the optical surface of the first lens close to the first polarizer, fs2 is a focal length of the optical surface of the first lens far from the first polarizer, F is an effective focal length of an optical module system, and R1 is a radius of curvature of the first lens.

If the focal length of the first lens is too small, i.e., | F1| <5.9F, the lens profile will be more curved, the lens thickness will be increased accordingly, which is not good for the module to be thin and light, and will also introduce larger aberration; if | F1| >53F, the optical power is small, which is not favorable for optimization of aberration.

The focal length of the optical surface of the first lens, which is close to the first polaroid, is more than or equal to 4.6F and less than or equal to | fs1| and less than or equal to 53F, the focal length of the optical surface of the first lens, which is far away from the first polaroid, is more than or equal to | fs2|, more than or equal to 2.6F, and the curvature radius of the corresponding first lens is more than or equal to-38 mm and less than or equal to R1 and less than or equal to-15 mm. The R1 is too large, such as R1< -15mm, which is not beneficial to the optimization of aberration, and the R1 is too small, such as R1< -40mm, which makes the optical path structure become complicated and increases the module thickness.

Further, in order to achieve a larger field angle, a light and thin effect, and a high-quality imaging effect, the optical module satisfies the following conditional expression:

0.4F≤f2≤0.6F；

|fs3|≥5F；

0.4F≤|fs4|≤0.54F；

wherein F2 is the focal length of the second lens, fs3 is the focal length of the optical surface of the second lens close to the first phase retarder, fs4 is the focal length of the optical surface of the second lens far away from the first phase retarder, and F is the effective focal length of the optical module system.

The second lens is the main source of the system focal power, if the focal length of the second lens is too large (F2>0.6F), i.e. the focal power is small, the other lenses will bear larger focal power, and extra lenses are needed to correct the aberration, which is not good for the module to be light and thin; if the focal length of the second lens is too small (F2 < 0.4F), i.e. the focal power is larger, the lens surface is too curved, which not only increases the difficulty of aberration correction, but also is not easy to process.

Further, the optical module set is characterized in that the total thickness of the optical module set is less than or equal to 11 mm.

In order to realize the light and thin of the VR module and provide better experience for a user, the thickness H of the optical system is less than or equal to 11mm, the VR wearing comfort degree is considered, meanwhile, better imaging quality can be obtained, and the eye distance (the axial distance between a human eye and a first optical surface) of the short-distance optical amplification module is set to be 8-20 mm.

The utility model also discloses a VR equipment, including above-mentioned arbitrary one the optical module.

The utility model provides a new optical module, with first polaroid design become can with the curved surface of first lens laminating, this optical module has compared in traditional design and has improved the design degree of freedom, provides the optics basis for reducing the aberration, under the prerequisite of guaranteeing the image quality, has further optimized thickness, the weight of VR module, realizes ultra-thin folding light path.

Drawings

FIG. 1 is a schematic diagram of an optical module according to the prior art;

fig. 2 is a schematic diagram of an optical path principle of an optical module according to a first embodiment of the present invention;

fig. 3 is a schematic structural diagram of an optical module according to a first embodiment of the present invention;

fig. 4 is a MTF graph of an optical module according to a first embodiment of the present invention;

fig. 5 is a field curvature graph of the optical module according to the first embodiment of the present invention;

fig. 6 is a distortion curve diagram of the optical module according to the first embodiment of the present invention;

fig. 7 is a MTF graph of an optical module according to a first embodiment of the present invention;

fig. 8 is a schematic structural diagram of an optical module according to a second embodiment of the present invention;

fig. 9 is a MTF graph of an optical module according to a second embodiment of the present invention;

fig. 10 is a field curvature graph of an optical module according to a second embodiment of the present invention;

fig. 11 is a distortion curve diagram of an optical module according to a second embodiment of the present invention;

fig. 12 is a MTF graph of an optical module according to a second embodiment of the present invention;

fig. 13 is a schematic structural diagram of an optical module according to a third embodiment of the present invention;

fig. 14 is a MTF graph of an optical module according to a third embodiment of the present invention;

fig. 15 is a field curvature graph of an optical module according to a third embodiment of the present invention;

fig. 16 is a distortion curve diagram of an optical module according to a third embodiment of the present invention;

fig. 17 is a MTF graph of an optical module according to a third embodiment of the present invention.

Description of the main elements

First lens	1
		Second lens	2
First polarizing plate	3
		First phase retarder	4
Display unit	5

Detailed Description

In order to facilitate understanding of the present invention, the present invention will be described more fully hereinafter with reference to the accompanying drawings. The embodiment of the invention is given in the attached drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, this embodiment is provided so that this disclosure will be thorough and complete.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

For convenience of explanation, the structural arrangement of the optical module is specifically described in each embodiment assuming that the indirect or direct pupil entrance side of the optical module is the image side and the incident side of the optical module is the object side.

Example 1

Referring to fig. 2 and 3, in order from an image side to an object side along a central optical axis, the optical modules in the first embodiment of the present invention include: a first polarizer 3, a first lens 1, a first phase retarder 4, a second lens 2 and a display cell 5.

The first polarizer 3 has a function of transmitting specific polarized light, and in particular, the first polarizer 3 may be a polarizing film. The first polarizer 3 has a concave image side and a convex object side.

The first lens 1 has a transmission magnifying function to magnify an image displayed by the display unit. The image side surface of the first lens 1 is concave, and the curvature radius of the first lens is matched with that of the first polaroid 3, namely, the first polaroid 3 can be attached to the image side surface of the first lens 1, or a reflective polarizing film can be directly plated on the image side surface of the first lens. The object-side surface of the first lens element 1 may be a plane or a convex surface, and in this embodiment, the object-side surface is a plane.

The second lens element 2 has a convex object-side surface and a convex image-side surface, and has a transmission and magnification function. The object side of the first lens is provided with a partial transmission partial reflector, such as a transflective film, so as to realize the functions of partial transmission and reflection of light.

The first phase retardation plate 4 may be, for example, 1/4 phase retardation plate to realize phase retardation of light. The object side surface and the image side surface of the first phase delay plate 4 are both flat plates, and two sides of the first phase delay plate 4 can be respectively attached to the adjacent optical surfaces of the first lens 1 and the second lens 2.

The display unit 5 is used for generating polarized light and providing an incident circularly polarized light or elliptically polarized light source for the optical module. In practical implementation, the display unit 5 may provide a display screen of a polarized imaging source, for example, the display screen may be a display screen coated with a second phase retarder having the same polarization direction as the first polarizer, and the display screen and the second phase retarder may be integrated together or may be independently disposed. The second phase retardation plate may be, for example, 1/4 phase retardation plate to realize the phase retardation of the light. The display screen is used for emitting linear polarized light beams, and the linear polarized light beams are changed into circularly polarized light or elliptically polarized light after passing through the second phase delay piece.

In the using process, an optical image emitted by the display unit 5 passes through the second lens 2, the first phase retarder 4 and the first lens 1, then reaches the first polarizer 3, is reflected, is secondarily amplified by the first lens 1, then passes through the first phase retarder 4 and the second lens 2, is partially reflected by the transmission part reflector on the second lens 2, and finally enters the sight line of human eyes through the first polarizer 3.

As shown in the figure, the specific working principle is as follows:

the circularly polarized light or elliptically polarized light E1 emitted by the display unit partially transmits through the partial transmission partial reflector, then is changed into a linearly polarized light beam E2 through the second lens 2 and the first phase retarder 4, the linearly polarized light beam E2 is incident to the first polarizer 3, the polarization direction of the first polarizer 3 is orthogonal to the polarization direction of the linearly polarized light beam E2, the linearly polarized light beam E2 is reflected by the first polarizer 3, is changed into circularly polarized light or elliptically polarized light E3 through the first lens 1 and the first phase retarder 4 again, the circularly polarized light or elliptically polarized light E4 is partially reflected through the second lens 3 and the partial transmission partial reflector again, the circularly polarized light beam E8683 passes through the first lens 1 and the first polarizer 3 after being changed into the linearly polarized light beam E5 for the third time, the polarization direction of the linearly polarized light beam E5 is in the same direction as that of the first polarizer 3, so that the linearly polarized light beam E5 can enter the, is incident on the eye pupil.

Specifically, the module parameter design in this embodiment is shown in table 1-1.

TABLE 1-1

The optical module shown in fig. 2 is from left to right, the module parameter data is shown in table 1-1, the first row OBJ represents the relevant parameter of the object plane, the second row paraxial plane, and the third row STO represents the diaphragm in the optical system, and the aperture is 4 mm. The fourth row represents the first polarizer in the optical module, which is of type STANDARD (Standard surface), made of H-K9L, 19.2mm in diameter, and 0 in aspheric coefficient; the fifth row and the sixth row respectively represent data corresponding to a first optical plane M1 and a second optical plane M2 of the first lens 1 (defining that the optical plane of the first lens 1 close to the first polarizer 3 is a first optical plane M1, and the optical plane far from the first polarizer 3 is a second optical plane M2), the radius of curvature of the first optical plane M1 is-16.275 mm, the radius of curvature of the second optical plane M2 is Infinity, the thickness of the first lens 1 is 1.297mm (i.e. the distance from the first optical plane M1 to the second optical plane M2, the thickness value in the data of the fifth row, the material is H-k12, the sixth row and the seventh row respectively represent data corresponding to the wave plate, the thickness is 0.5mm, the seventh row and the eighth row are a 3 optical plane M3 and a fourth optical plane M4 of the second lens 2 (here defining: the optical plane M3 close to the first optical plane is a third optical retardation plane M3, the optical surface of the second lens 2 away from the first phase retarder is a fourth optical surface S4), the radius of curvature of the third optical surface is Infinity (flat plate), the radius of curvature of the fourth optical surface is-21.952 mm, the thickness is 7.072mm (data corresponding to row 7), and the material is H-K2. The data of the reflection of the light between the lens 1 and the lens 2 in the lines 8 to 16 are not described in detail herein. The glass film of the seventeenth behavior display screen is made of H-K9L and has a thickness of 0.4 mm. The eighteenth action, IMAG, represents the final imaging of the light.

The values of the optical characteristic parameters of the optical module in this embodiment are shown in tables 1-2.

Tables 1 to 2

Display screen size (inch)	2.1
		Angle of vision (°)	100
Focal length of system (mm)	18.34
		Eye movement range (mm)	4
Screen resolution	2000*2000
		Thickness of optical system (mm)	10.8
Eye distance (mm)	8
		Aperture	5
Optical outside diameter (mm)	28
		Distortion of system	12.9
Lens weight (g)	45.3
		Total length (mm)	18.9

According to the design parameters, the focal length F1 of the first lens 1 is-969.243 mm (-53F), the focal length F2 of the second lens 2 is 7.3mm (0.4F), the thickness of the optical system is 10.8mm, and the optical system with the system focal length of 18.34mm and the field angle of 100 degrees can be obtained. The aperture is designed to be 5, and the corresponding aperture diaphragm is 3.7mm, so that the eye movement range of 4mm can be obtained.

Meanwhile, the screen size of the display screen is designed to be 2.1 inches, the contact distance is 8mm, the MTF curve shown in figure 4 is combined, the abscissa value of the MTF of the average ordinate of each field of view, which is greater than 0.05, is taken as the cut-off frequency, and then the supported resolving power is 2000 x 2000, the distortion rate is controlled to be (-12.9%, 0), and the field curvature is controlled to be (-2mm,2 mm).

Fig. 5 and fig. 6 show the field curvature curve graph and the distortion curve graph of the optical module, respectively, and it can be seen from fig. 5 that the field curvature of the optical imaging module is well corrected. As can be seen from the distortion curve of FIG. 6, the optical imaging module has a better imaging effect. The distortion is well corrected.

From the MTF graph shown in fig. 7, at 25 ° of half field, the T-direction MTF is 0.68; the T-direction MTF was 0.76 at 20 ° and 0.75 at 10 °. It can be seen that the imaging effect of the central field of view region is better, and the high-definition effect can be realized.

Example 2

Please refer to fig. 8, which is a difference between the optical module of the second embodiment of the present invention and the first embodiment, in which the second optical surface M2 of the first lens 1 away from the first polarizer 3 is convex, the third optical surface M3 of the second lens 2 close to the first retarder 4 is concave, and the first lens 1, the first retarder 4 and the second lens 2 are separately disposed. Can reduce the system field curvature through this setting, strengthen the formation of image quality to can further reduce optical system total length and alleviate module weight, bring more comfortable experience for the user.

Specifically, the lens design parameters in this embodiment are shown in table 2-1.

TABLE 2-1

The values of the optical characteristic parameters of the optical module in this embodiment are shown in table 2-2.

Tables 2 to 2

Display screen size (inch)	2.1
		Angle of vision (°)	100
Focal length of system (mm)	19.73
		Eye movement range (mm)	4
Screen resolution	2700*2700
		Thickness of optical system (mm)	9.2
Eye distance (mm)	8
		Aperture	4
Optical outside diameter (mm)	33
		Distortion of system	17.3
Lens weight (g)	28.94
		Total length (mm)	18.1

According to the above design parameters, the focal length of the first lens 1 is 141.815mm (7.18F), wherein the focal length of the second optical surface M2 of the first lens is-1033.054 mm (-52F), and the focal length of the first optical surface M1 of the first lens is 124.767mm (6.3F); the focal length of the second lens is 9.538mm (0.48F), wherein the focal length of the third optical surface M3 of the second lens is-128.515 mm (-6.5F), the focal length of the fourth optical surface M4 of the first lens is 9.085mm (0.46F) and the optical thickness of the system is 9.2mm, and an optical system with the effective focal length of the system being 19.73mm and the large field angle being 100 degrees can be obtained.

Meanwhile, the screen size is designed to be 2.1 inches, the contact distance is 8mm, and the MTF curve shown in FIG. 9 is combined, the abscissa value of MTF larger than 0.05 of the average ordinate of each field is taken as the cut-off frequency, so that the supported resolving power is 2700 x 2700, the distortion rate is controlled to be (-17.3%, 0), and the field curvature is controlled to be (-0.5mm,0.5 mm).

Fig. 10 and 11 show the field curvature graph and the distortion graph of the optical module, respectively, and it can be seen from fig. 10 that the field curvature of the optical module is well corrected. As can be seen from the distortion curve of fig. 11, the optical module has a better imaging effect. The distortion is well corrected.

From the MTF graph shown in fig. 12, at 30 ° of half field of view, the T-direction MTF is 0.4; the T-direction MTF was 0.68 at 20 ° and 0.84 at 10 °. It can be seen that high definition effect can be achieved in the full view field.

Example 3

On the basis of the embodiment 2, because the distortion is 17.3% when the visual field is 100 degrees, the distortion of the VR optical system can be slightly larger, the visual field is continuously increased to 120 degrees, and the optimal design is carried out.

Specifically, the design parameters of the lens in the optical module in this embodiment are shown in table 3-1.

TABLE 3-1

The values of the optical characteristic parameters of the optical module in this embodiment are shown in table 3-2.

TABLE 3-2

Display screen size (inch)	2.1
		Angle of vision (°)	120
Focal length of system (mm)	18.64
		Eye movement range (mm)	4
Screen resolution	4000*4000
		Thickness of optical system (mm)	9.7
Eye distance (mm)	8
		Aperture	4
Optical outside diameter (mm)	40
		Distortion of system	39.6
Lens weight (g)	54.9
		Total length (mm)	18.6

According to the design parameters, the focal length F1 of the first lens 1 is 111.377mm (5.97F), wherein the focal length of the first optical surface M1 of the first lens close to the first polarizer side is-87.202 mm (-4.67F), and the focal length of the second optical surface M2 far away from the first polarizer side is 49.199mm (2.64F). The focal length of the second lens 2 is 10.979mm (0.59F), wherein the focal length of M3 of the third optical surface of the second lens close to the first phase retarder side is-97.044 mm (-5.2F), the focal length of M4 of the fourth optical surface far away from the first phase retarder side is 10.135mm (0.54F) and the system optical thickness is 9.7mm, and an optical system with the system effective focal length of 18.64mm and a large field angle of 120 degrees can be obtained.

Meanwhile, the screen size is designed to be 2.1 inches, the contact distance is 8mm, and the abscissa value of MTF (mean ordinate MTF) larger than 0.05 of each field of view is taken as a cut-off frequency in combination with the MTF curve shown in FIG. 14, so that the supported resolving power is 4000 x 4000, the distortion rate is controlled to be (-39.6%, 0), and the field curvature is controlled to be (-0.5mm,0.5 mm).

Fig. 15 and 16 show the field curvature curve graph and the distortion curve graph of the optical module, respectively, and it can be seen from fig. 15 that the field curvature of the optical imaging module is well corrected. As can be seen from the distortion curve of fig. 16, the optical module has a better imaging effect. The distortion is well corrected.

From the MTF graph shown in fig. 17, at half field of view 30 °, the T-direction MTF is 0.4; the T-direction MTF was 0.68 at 20 ° and 0.84 at 10 °. It can be seen that high-definition effect can be obtained in the whole visual field.

Example 4

A fourth embodiment of the present invention provides a VR device, where the VR device at least includes the optical module in any of the above embodiments, and the virtual reality device is, for example, a VR helmet or VR glasses.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above-mentioned embodiments only express the embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. An optical module is characterized by sequentially comprising a first polaroid, a first lens, a first phase retarder, a second lens and a display unit, wherein the first polaroid is a curved surface, the adjacent surfaces of the first polaroid and the first lens can be jointed in a surface mode, a partial transmission partial reflector is arranged on the optical surface of the second lens adjacent to the display unit, and the display unit is used for providing an incident polarized light source of the optical module.

2. The optical module of claim 1 wherein the first polarizer is a curved reflective polarizing film overlying the optical surface of the first lens adjacent the first polarizer.

3. The optical module of claim 1 wherein the optical surface of the first lens adjacent the first polarizer is concave.

4. The optical module of claim 1 wherein the first retarder is conformable to the adjacent surfaces of the first lens and the second lens.

5. The optical module of claim 1 wherein the optical module satisfies the conditional expression:

5.9F≤|f1|≤53F；

4.6F≤|fs1|≤53F；

|fs2|≥2.6F；

-38mm≤R1≤-15mm；

wherein F1 is a focal length of the first lens, fs1 is a focal length of an optical surface of the first lens close to the first polarizer, fs2 is a focal length of an optical surface of the first lens far from the first polarizer, F is an effective focal length of an optical module system, and R1 is a curvature radius of the first lens.

6. The optical module of claim 1 wherein the optical module satisfies the conditional expression:

0.4F≤f2≤0.6F；

|fs3|≥5F；

0.4F≤|fs4|≤0.54F；

7. The optical module of claim 1, wherein the display unit includes a display screen and a second phase retarder, the second phase retarder being adjacent to the second lens.

8. The optical module of claim 1, wherein the display unit is disposed coaxially or non-coaxially with the optical module.

9. A VR device comprising an optical module according to any one of claims 1 to 8.