CN116430654B

CN116430654B - Projection optical modules, projection display systems, and wearable devices

Info

Publication number: CN116430654B
Application number: CN202310266012.8A
Authority: CN
Inventors: 郭恒琳
Original assignee: Goertek Optical Technology Co Ltd
Current assignee: Goertek Optical Technology Co Ltd
Priority date: 2023-03-15
Filing date: 2023-03-15
Publication date: 2025-10-10
Anticipated expiration: 2043-03-15
Also published as: CN116430654A; WO2024187756A1

Abstract

The present application discloses a projection optical module, a projection display system, and a wearable device. The projection optical module includes a beam splitter prism, comprising a light incident surface, an emission surface, a first light-transmitting surface, and a second light-transmitting surface. The projection optical module also includes a projection lens assembly, wherein the beam splitter prism is disposed in the projection light path of the projection lens assembly, and at least two surfaces of the beam splitter prism are disposed adjacent to the projection lens assembly. The effective focal length (EFFL) of the projection optical module is 6 mm < EFFL < 10 mm. The projection optical module provided in the present application achieves high-resolution projection while maintaining a compact design.

Description

Projection optical module, projection display system and wearable equipment

Technical Field

The application belongs to the technical field of optical projection, and particularly relates to a projection optical module, a projection display system and wearable equipment.

Background

Nowadays, with the development of electronic technology, various intelligent wearable devices have been developed. For example, augmented reality devices (AR, augmented ReaHity), virtual reality devices (VR, virtual h ReaHity), and mediated reality devices (MR, mediated ReaHity) and XR devices, among others, are becoming increasingly interesting and favored by consumers. Taking the AR device as an example, the main form of AR device currently includes AR glasses or AR helmets, which all belong to the head-mounted device. Currently, AR devices are generally heavy in weight, which is contrary to the first performance requirement of AR devices that are wearable comfort, including miniaturization and lightweight. In order to improve the use experience of users, the lightweight design of AR is an important development direction of AR glasses.

Disclosure of Invention

The application aims to provide a novel technical scheme of a projection optical module, a projection display system and a wearable device, and solves the problem that the projection optical module in the existing wearable device cannot give attention to high-resolution projection under the conditions of small volume and light weight.

According to a first aspect of the present application, there is provided a projection optical module including:

the light-splitting prism comprises a light-in surface, an emergent surface, a first light-transmitting surface and a second light-transmitting surface;

The beam splitting prism is arranged in a projection light path of the projection lens group, and at least two surfaces of the beam splitting prism are arranged adjacent to the projection lens group;

The effective focal length EFFL of the projection optical module is 6mm < EFFL <10mm.

Optionally, a polarizing element is disposed on the light incident path of the light splitting prism, and the polarizing element and the light incident surface are disposed adjacently;

the projection lens group comprises a lens group positioned on one side of the emergent surface, a fourth lens positioned on one side of the first light-transmitting surface and a fifth lens positioned on one side of the second light-transmitting surface;

a phase retarder is arranged between the first light-transmitting surface and the fourth lens, and projection light rays can pass through the phase retarder twice.

Optionally, the fourth lens has an effective focal length EFFL ₄ of 5mm < EFFL ₄ <9mm.

Optionally, the effective focal length EFFL ₅ of the fifth lens is 16mm < EFFL ₅ <23mm.

Optionally, the lens group includes a first lens, a second lens and a third lens sequentially arranged along the same optical axis;

the first lens and the second lens are mutually glued to form a glued lens group, and the glued lens group is positioned between the beam splitting prism and the third lens.

Optionally, the effective focal length EFFL ₁ of the first lens is-8 mm < EFFL ₁ < -6mm;

the effective focal length EFFL ₂ of the second lens is 8mm < EFFL ₂ <13mm.

Optionally, the effective focal length EFFL ₃ of the third lens is 12mm < EFFL ₃ <19mm.

Optionally, the beam splitting prism includes a first prism and a second prism connected to each other, and a beam splitting film is disposed between the first prism and the second prism.

Optionally, the light incident surface and the light emergent surface are arranged opposite to each other, and the first light transmitting surface and the second light transmitting surface are arranged opposite to each other, or

The light incident surface and the emergent surface are adjacently arranged, and the first light transmitting surface and the second light transmitting surface are adjacently arranged.

Optionally, the projection light is incident to a polarizing element, the polarizing element can transmit S light to the beam splitting prism, a beam splitting film in the beam splitting prism reflects S light to transmit P light, the P light is transmitted to the retarder through the beam splitting film, is transmitted to the fourth lens through the retarder, is reflected to the retarder through the fourth lens, and is further transmitted to the beam splitting film, the P light is modulated into S light, the S light is reflected to the exit surface through the beam splitting film, and reaches the exit pupil through the lens group.

According to a second aspect of the present application, there is also provided a projection display system. The projection display system includes:

The light source module is used for generating projection light rays, and the projection light rays comprise light rays with different wave bands;

the projection optical module of the first aspect, which is located on the optical path transmission path of the light source module, and

And the projection chip is positioned at one side of the fifth lens, which is away from the beam-splitting prism.

Optionally, the projection display system further includes a field lens located between the light source module and the projection optical module;

The field lens is a lens with positive focal power, two surfaces of the field lens are convex surfaces, and the field lens is used for collecting the projection light rays to the projection optical module;

the polarizing element is positioned between the field lens and the beam splitting prism, and the polarizing element is arranged on the light incident surface.

Optionally, the projection display system further comprises a light homogenizing element, wherein the light homogenizing element is located between the light source module and the field lens, and the light homogenizing element is a compound spectacle lens made of plastic materials.

Optionally, the light source module comprises a light source and a collimating lens group, and the collimating lens group is positioned on a light path transmission path of the light source;

the light source comprises a plurality of light emitting chips with different colors, the light emitting chips are arranged to form a target array, and the center of the target array is positioned on the optical axis of the collimating lens group;

the projection light rays emitted by the collimating lens group can be directly subjected to light homogenizing treatment.

Optionally, the collimating lens group comprises a first collimating lens and a second collimating lens which are arranged along the same optical axis at intervals, wherein the second collimating lens comprises at least one aspheric surface;

The focal power of the first collimating lens and the second collimating lens is positive;

the first collimating lens and the second collimating lens are used for collimating the projection light into parallel light and then emitting the parallel light.

According to a third aspect of the present application, there is also provided a wearable device. The wearable device includes:

A housing, and

The projection display system of the second aspect.

The application has the beneficial effects that:

The projection optical module provided by the embodiment of the application is a miniaturized and light LCOS projection optical framework, has better projection quality in small-volume design, is simpler in design of the whole light path, and can be matched with a single multicolor light source in application, so that the use number of optical devices on the light incident side is reduced, the miniaturization and light weight of wearable equipment are realized, and the cost is saved.

Other features of the present application and its advantages will become apparent from the following detailed description of exemplary embodiments of the application, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description, serve to explain the principles of the application.

FIG. 1 is a schematic diagram of a projection optical module according to an embodiment of the present application;

FIG. 2 is a second schematic diagram of a projection optical module according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a projection display system according to an embodiment of the present application;

FIG. 4 is a schematic diagram of a light source according to an embodiment of the present application;

FIG. 5 is a graph of MTF at various fields of view for a projection display system according to an embodiment of the present application;

Fig. 6 is a distortion chart of a projection display system according to an embodiment of the present application under each view field.

Reference numerals illustrate:

1. The light-emitting diode comprises a light-splitting prism, 101, a light-incident surface, 102, an emergent surface, 103, a first light-transmitting surface, 104, a second light-transmitting surface, 2, a polarizing element, 3, a first lens, 4, a second lens, 5, a third lens, 6, a fourth lens, 61, a first surface, 62, a second surface, 7, a fifth lens, 8, a phase retarder, 9, a light-splitting film, 10, a projection chip, 11, a field lens, 12, a light-homogenizing element, 13, a light source, 131, a light-emitting chip, 14, a first collimating lens, 15 and a second collimating lens.

Detailed Description

Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application unless it is specifically stated otherwise.

The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the application, its application, or uses.

Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of exemplary embodiments may have different values.

It should be noted that like reference numerals and letters refer to like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.

The projection optical module, the projection display system and the wearable device according to the embodiments of the present application are described in detail below with reference to fig. 1 to 6.

The projection optical module provided by the embodiment of the application can be applied to a projection display system. The projection optical module and the light source module are matched to form the projection display system. The projection display system may be applied in, for example, an AR device. The projection optical module is used as a projection light path part of the projection display module, and projection light rays emitted by the light source module (used as an illumination light path part) can be used.

Referring to fig. 1 and 2, the projection optical module provided in the embodiment of the application includes a beam splitting prism 1 and a projection lens set. The light splitting prism 1 includes a light incident surface 101, an exit surface 102, a first light transmitting surface 103, and a second light transmitting surface 104. The beam splitting prism 1 is arranged in a projection light path of the projection lens group, and the beam splitting prism 1 is provided with at least two surfaces which are adjacently arranged with the projection lens group. The effective focal length EFFL of the projection optical module is 6mm < EFFL <10mm.

According to the embodiment of the application, the effective focal length of the projection optical module can be 6 mm-10 mm, and the projection optical module has the characteristic of small effective focal length.

In a preferred embodiment of the present application, the effective focal length of the projection optical module is, for example, 6mm to 9.7mm. At which a clear image can be obtained.

The beam splitting prism 1 is located between the projection light paths of the projection lens group. For example, referring to fig. 1 and 2, the lenses in the projection lens group are enclosed outside the first light-transmitting surface 103, the second light-transmitting surface 104 and the light-emitting surface 102 of the light-splitting prism 1, and the arrangement is compact. The whole projection optical module realizes the design of volume miniaturization and simultaneously can give consideration to the projection quality of high resolution.

According to the projection optical module provided by the embodiment of the application, the exit pupil size of the projection optical module is 3.3 mm-4 mm, the F number is 1.8-2.4, and the field angle FOV is less than or equal to 30 degrees. This allows a good projection effect compared to an optical frame of the same volume.

In some examples of the present application, referring to fig. 1 and 2, a polarizing element 2 is disposed on the light incident path of the beam splitter prism 1, the polarizing element 2 is disposed adjacent to the light incident surface 101, the projection lens group includes a lens group located on the outgoing surface 102 side, a fourth lens 6 located on the first light transmitting surface 103 side, and a fifth lens 7 located on the second light transmitting surface 104 side, a phase retarder 8 is disposed between the first light transmitting surface 103 and the fourth lens 6, and the projection light can pass through the phase retarder 8 twice.

According to the above example of the present application, the projection lens group may include one lens group located on the light exit path of the light splitting prism 1, and further include a fourth lens 6 located on the first light transmission surface 103 side of the light splitting prism 1, and a fifth lens 7 located on the second light transmission surface 104 side of the light splitting prism 1. The beam splitting prism 1 is located between the projection light paths of the projection lens group.

Optionally, each lens included in the projection lens set may be made of glass, which may make the temperature resistance of the entire projection optical module better.

The fifth lens 7 is disposed adjacent to the second light-transmitting surface 104 of the light-splitting prism 1.

Specifically, the fifth lens 7 may be disposed between the beam splitter prism 1 and an LCOS image plane (such as the projection chip 10 shown in fig. 1 to 3), and the fifth lens 7 may function to correct distortion and spherical aberration. This facilitates the improvement of the final projection quality.

According to the projection optical module provided by the embodiment of the application, the MTF value of each view field is higher, namely the definition of the image projected by the projection optical module under each view field is very good. In addition, the TV distortion after being projected by the projection optical module under each view field is smaller, and the requirement of human eyes on the distortion can be completely met.

The fourth lens 6 includes two surfaces, which are defined as a first surface 61 and a second surface 62, respectively, referring to fig. 3, the first surface 61 is close to the first light-transmitting surface 103 of the light-splitting prism 1, and the second surface 62 is far from the first light-transmitting surface 103 of the light-splitting prism 1. A phase retarder 8 is provided between the first surface 61 and the first light-transmitting surface 103. On the basis of this, the first surface 61 may form a transmissive surface and the second surface 62 may form a reflective surface.

For example, the projection light entering the beam splitter prism 1 may be transmitted through the retarder 8 (first passing through the retarder 8), then transmitted through the first surface 61 of the fourth lens 6, and then reflected to the retarder 8 (second passing through the retarder 8 at this time) through the second surface 62, and after passing through the retarder 8 twice, the polarization direction of the projection light is rotated by 90 °, and then the projection light is reflected by the beam splitter prism 1 and then emitted through the exit surface 102, and reaches the exit pupil position after passing through the lens group, so that the end user can see the high-definition projection image.

Optionally, the phase retarder 8 is a quarter wave plate.

Of course, the phase retarder 8 may be other forms such as a half wave plate, which is not limited in the embodiment of the present application.

The phase retarder 8 may be disposed on the first light-transmitting surface 103 of the beam-splitting prism 1, for example.

The surface of the fourth lens 6 facing away from the first light-transmitting surface 103 is a second surface 62, and a reflective film may be disposed on the second surface 62, so that the second surface 62 is a reflective surface.

The projection optical module provided by the implementation of the application has the advantages that the folded optical path is designed, so that the formed optical framework can realize the projection design of a larger FOV. Furthermore, the optical efficiency of the module can be improved based on the design of the folded optical path.

Optionally, the effective focal length EFFL ₄ of the fourth lens 6 is 5mm < EFFL ₄ <9mm.

For example, the thickness H ₄ of the fourth lens 6 may be designed to be 0.6mm < H ₄ <2mm.

For example, the fourth lens 6 comprises at least one convex surface.

Further, the fourth lens 6 includes a first surface 61 and a second surface 62, the first surface 61 and the first light-transmitting surface 103 of the beam-splitting prism 1 are disposed adjacently, a phase retarder 8 is disposed therebetween, and the phase retarder 8 is disposed on the first surface 61, wherein the second surface 62 may be disposed as a convex surface.

Optionally, the effective focal length EFFL ₅ of the fifth lens 7 is 16mm < EFFL ₅ <23mm.

For example, the thickness H ₅ of the fifth lens 7 may be designed to be 0.5mm < H ₄ <1mm.

For example, a surface of the fifth lens 7 near the first light-transmitting surface 103 is convex, and a surface of the fifth lens 7 far from the first light-transmitting surface 103 is concave.

As a preferable mode of the present application, the effective focal length EFFL ₅ of the fifth lens 7 is 16mm < effl ₅ <22.4mm, and the thickness H ₅ of the fifth lens 7 is 0.53mm < H ₄ <0.95mm.

The fifth lens 7 is located at one side of the second light-transmitting surface 104 of the beam-splitting prism 1, and the fifth lens 7 is used for correcting distortion and spherical aberration. For example, the distortion value of the projection optical module under each view field is smaller than 1.1%, which indicates that the projection quality is good.

In some examples of the application, the lens group comprises a first lens 3, a second lens 4 and a third lens 5 which are sequentially arranged along the same optical axis, wherein the first lens 3 and the second lens 4 are mutually glued to form a gluing lens group, and the gluing lens group is positioned between the beam splitting prism 1 and the third lens 5.

According to the projection optical module provided in the embodiment of the present application, a lens group is disposed at one side of the exit surface 102 of the beam splitter prism 1, and the lens group may include three lenses, which are the first lens 3, the second lens 4, and the third lens 5. The three lenses are matched with each other to improve projection quality. On this basis, the projection lens group may include five lenses in combination with the fourth lens 6 and the fifth lens 7 described above.

As a preferable implementation mode of the application, the projection optical module comprises five lenses made of glass materials, and the effective focal length of the projection optical module is 6 mm-9.7 mm.

The two lenses close to the exit surface 102 of the beam splitter prism 1, that is, the first lens 3 and the second lens 4 are double-glued pieces, and the two are glued together, so that the design can reduce the chromatic aberration of the whole projection optical module, and is beneficial to improving the projection quality.

The third lens 5 and the gluing lens group are adjacent and are arranged at intervals, and the third lens 5 can collect projection light to reduce the aperture of the lens, so that the short-focus projection design of the whole projection optical module is facilitated. For example, the effective focal length of the projection optical module is 6 mm-9.7 mm.

Optionally, the effective focal length EFFL ₁ of the first lens 3 is-8 mm < EFFL ₁ < -6mm, and the effective focal length EFFL ₂ of the second lens 4 is 8mm < EFFL ₂ <13mm.

For example, the first lens 3 and the second lens 4 form a cemented lens group, and the cemented lens group has a thickness H ₁₂ of 1mm < H ₁₂ <2mm.

As a preferable mode of the application, the effective focal length EFFL ₁ of the first lens 3 is-8 mm < EFFL ₁ < -6.4mm, the effective focal length EFFL ₂ of the second lens 4 is 8mm < EFFL ₂ <12.1mm, the thickness of a bonding lens group formed by the first lens 3 and the fourth lens 6 is 1.2mm < H ₁₂ <2.0mm, and the bonding lens formed by the bonding lens has the characteristics of short focal length and smaller thickness dimension, thereby being beneficial to realizing the short focal design of the whole projection optical module, being capable of realizing the miniaturization and light weight of the projection optical module and being capable of considering the projection quality on the basis.

For example, the first lens 3 comprises at least one concave surface.

For example, the surface of the second lens 4 facing away from the first lens 3 is convex.

By reasonably designing the surface shapes of the first lens 3 and the second lens 4, the bonding of the two is facilitated, and the lateral size of the formed bonding lens can be reduced.

The abbe number of the first lens 3 is v ₁, the abbe number of the second lens 4 is v ₂, and the abbe numbers of the first lens 3 and the second lens 4 satisfy v ₂≥2v₁. By reasonable collocation of abbe numbers of the two cemented lenses, dispersion can be reduced.

Optionally, the effective focal length EFFL ₃ of the third lens 5 is 12mm < EFFL ₃ <19mm.

As a preferable mode of the present application, the effective focal length EFFL ₃ of the third lens 5 is 12mm < effl ₃ <18.3mm.

By reasonably matching the effective focal lengths of the lenses positioned on the emergent surface 102 of the beam splitter prism 1, the short-focus design of the whole projection optical module can be realized, and the quality requirement of projection is considered.

For example, the thickness H ₃ of the third lens 5 may be designed to be 0.4mm < H ₃ <0.8mm.

For example, both surfaces of the third lens 5 are convex.

The third lens 5 can be designed to be thin, which is advantageous in achieving a reduction in the lateral dimension of the entire projection optical module while also reducing the weight.

In some examples of the present application, referring to fig. 1 and 2, the beam-splitting prism 1 includes a first prism and a second prism connected to each other, and a beam-splitting film 9 is disposed between the first prism and the second prism.

That is, the beam splitter prism 1 may be formed as a whole by combining two prisms. The junction of the two prisms forms a bevel, see fig. 1 and 2, between which for example a light-splitting film 9 is attached.

The light-splitting film 9 may transmit a part of the projection light and may reflect a part of the projection light. The light transmittance of the spectroscopic film 9 (PBS film) can be adjusted as needed.

Specifically, the projection optical module is provided with the beam splitting film 9, the phase retarder 8 and the polarizing element 2 to form a folded optical path. The light splitting film 9 (PBS film) is interposed between the first prism and the second prism, the polarizing element 2, for example, a polarizing film (POL film), is disposed on the light incident surface 101 of the light splitting prism 1, and the phase retarder 8, for example, a quarter wave plate (QWP film), is attached to the first light transmitting surface 103 of the light splitting prism 1. The polarization direction of the polarizer 2 is, for example, S-light transmission.

Of course, the polarization direction of the polarizer 2 may be P-light transmission, which is not limited in the present application.

Wherein the phase retarder 8 comprises a quarter wave plate. The fast axis of the phase retarder 8 is arranged at 45 degrees to the edge of the splitting prism 1.

According to the projection optical module provided by the embodiment of the application, the beam splitter prism 1 includes a light incident surface 101, an exit surface 102, a first light transmitting surface 103 and a second light transmitting surface 104, and the arrangement positions and directions of the light incident surface 101, the exit surface 102, the first light transmitting surface 103 and the second light transmitting surface 104 are different according to the different positions of the incident light source.

For example, referring to fig. 1, the light incident surface 101 is disposed opposite to the light emergent surface 102, and the first light transmitting surface 103 is disposed opposite to the second light transmitting surface 104.

For another example, referring to fig. 2, the light incident surface 101 is disposed adjacent to the light emitting surface 102, and the first light transmitting surface 103 is disposed adjacent to the second light transmitting surface 104.

Referring to fig. 1 and 2, fig. 2 is a modification of the optical architecture of the projection optical module shown in fig. 1. In a specific application, the relative positions of the first lens 3, the second lens 4, the third lens 5, the fourth lens 6 and the fifth lens 7 may be adjusted and changed according to the different positions and directions of the light incident surface 101 and the light emergent surface 102 of the light splitting prism 1, and the first light transmitting surface 103 and the light emergent surface 102.

Referring to fig. 2, the first lens 3 and the second lens 4 still form a cemented lens, the third lens 5 is disposed adjacent to and spaced apart from the cemented lens, the first lens 3, the second lens 4 and the third lens 5 form a lens group and then are located at one side of the exit surface 102 of the light splitting prism 1, the fourth lens 6 is located at one side of the first light transmitting surface 103 of the light splitting prism 1, and the fifth lens 7 is located at one side of the second light transmitting surface 104 of the light splitting prism 1. The difference from the optical architecture shown in fig. 1 and fig. 2 is that the light incident surface 101 and the light emergent surface 102 of the light splitting prism 1, and the first light transmitting surface 103 and the second light transmitting surface 104 are not disposed opposite to each other but disposed adjacently.

Referring to the projection optical modules shown in fig. 1 and 2, the optical paths are almost identical to the projection optical paths, and the optical performances of the two optical architectures are almost identical, although the optical structures are different in design. The meaning of the optical conversion architecture is that the optical conversion can be flexibly converted according to the assembly requirement of the rear end, but at this time, it is noted that the illumination efficiency of the illumination light path part is slightly different due to the different transmittance and reflectance of the polarization light by the beam splitter prism 1 when passing through the architecture twice.

According to the projection optical module provided by the embodiment of the application, the light path propagation path is as follows:

the projection light is incident to the polarizing element 2, the polarizing element 2 can transmit the S light to the light splitting prism 1, the light splitting film 9 in the light splitting prism 1 reflects the S light to transmit the P light, the P light is transmitted to the retarder 8 through the light splitting film 9, is transmitted to the fourth lens 6 through the retarder 8, is reflected to the retarder 8 through the fourth lens 6 and is further reflected to the light splitting film 9, the P light is modulated into the S light, the S light is reflected to the emergent surface 102 through the light splitting film 9, and is transmitted to the exit pupil through the lens group.

According to another embodiment of the present application, there is provided a projection display system, referring to fig. 3, including a light source module, a projection optical module as described above, and a projection chip 10. The light source module is used for generating projection light, the projection light comprises light rays with various different wave bands, and the projection optical module is located on a light path transmission path of the light source module. The projection chip 10 is located on the side of the fifth lens 7 facing away from the beam splitter prism 1.

The projection display system provided in the above embodiment of the present application includes a light source module, as shown in fig. 3, which is an illumination light path design, and belongs to an illumination light path portion of the projection display system.

The light source module is, for example, a multicolor light source. The light source module can emit projection light for projection, and the projection light can comprise light rays with various different wave bands, such as green light, red light, blue light and the like.

Of course, the light source module in the embodiment of the application includes, but is not limited to, light capable of emitting light of three colors, and light of other colors can be emitted, so long as visible light can be emitted.

In some examples of the application, referring to fig. 3, the projection display system further comprises a field lens 11 located between the light source module and the projection optical module. The field lens 11 is a lens with positive focal power, two surfaces of the field lens 11 are convex surfaces, and the field lens 11 is used for converging the projection light to the projection optical module. The polarizing element 2 is located between the field lens 11 and the beam splitter prism 1, and the polarizing element 2 is disposed on the light incident surface 101.

In the projection display system provided by the embodiment of the application, the field lens 11 is introduced and the field lens 11 is arranged at the light incident side of the projection optical module, namely, at a proper position between the light source module and the projection optical module, the focal power of the field lens 11 is positive, and the field lens 11 can be used for converging the projection light to the projection optical module, which is beneficial to improving the light efficiency.

In some examples of the present application, referring to fig. 2, the projection display system further includes a light homogenizing element 12, where the light homogenizing element 12 is located between the light source module and the field lens 11. Wherein, the light homogenizing element 12 is a compound spectacle lens made of plastic material.

The light homogenizing element 12 can perform light homogenizing treatment on the projection light emitted by the light source module, which is beneficial to improving the final projection quality.

Wherein, the dodging component 12 can select a compound spectacle lens.

The material of the compound spectacle lens can be designed into plastic materials, for example. The weight is lighter, the weight of the whole equipment is reduced, and the comfort of wearing by a user can be improved.

In some examples of the present application, the light source module includes a light source 13 and a collimating lens group, and the collimating lens group is located on a light path transmission path of the light source 13, where, referring to fig. 4, the light source 13 includes a plurality of light emitting chips 131, and the plurality of light emitting chips 131 are arranged to form a target array, and a center of the target array is located on an optical axis of the collimating lens group. The projection light rays emitted by the collimating lens group can be directly subjected to light homogenizing treatment.

According to the above example of the present application, for example, by arranging a plurality of different light emitting chips 131, a target array may be formed, which may form a multi-color light source, that is, the above-mentioned light source 13. This design makes it possible to emit projection light comprising, for example, at least three different wavelength bands using only one light source 13. And, the projection light emitted by the light source 13 can be collimated by a single collimating lens set arranged on a single optical channel, and after being collimated by the collimating lens set, the light spots of the light rays with various colors have better uniformity, so that the requirement of watching by eyes of people can be completely met.

Moreover, the projection light rays emitted by the collimating lens group can be directly subjected to light homogenizing treatment without light combination, so that the structural design of the whole light source module is greatly simplified.

That is, the above-described light source 13 employs an all-in-one light source. For example, the RGB light source is integrated on one LED, and in the illumination light path part, the collimation dodging light path only needs to be provided with a single channel, so that the sizes of the other two directions are greatly reduced. Thereby greatly reducing the thickness and volume of the whole light source module. When the light source module is applied to a projection display system, the light source module is favorable for realizing the light weight and the miniaturization of related equipment.

Referring to fig. 4, in forming the light source 13, the center of the target array formed by arranging the plurality of light emitting chips 131 is designed to be located on the optical axis of the collimating lens group, that is, the center of the target array is coaxial with the center of the collimating lens group. Under the design, after the collimating lens group collimates the light rays with the corresponding wavelengths emitted by each light emitting chip 131, the uniformity of the light rays with various colors is better.

The light source module set provided in the above embodiment of the present application can be applied to a projection display system as an illumination light path, a single light source 13 can integrate a plurality of light emitting chips 131, only one collimating lens set can be used to collimate light rays with different colors, and the collimating effect is better, the whole light path design does not need to be provided with a light splitting element to combine light, and the light source module set can directly enter even light, so that the light source module set can realize small-volume illumination. Furthermore, the single light source 13 can also realize high-luminance illumination due to the plurality of light emitting chips (light emitting surfaces).

In the above-described example of the present application, when forming the single light source 13, the plurality of light emitting chips 131 are symmetrically arranged on the peripheral side thereof with the optical axis of the collimator lens group as the central axis, and the center of the target array of the formed light source 13 is located on the optical axis of the collimator lens group. On this basis, the corresponding light rays emitted by each light emitting chip 131 can be collimated by a collimating lens set close to the optical axis, and the plurality of light emitting chips 131 are symmetrically arranged, so that uniformity can be mutually compensated during collimation, uniformity of the collimated light rays of all colors is good, and viewing requirements of human eyes can be completely met.

For example, referring to fig. 4, the green light chips G are arranged in two, two green light chips G form one set of diagonally symmetrical arrangement, the red light chips R and the blue light chips B are respectively arranged in one set, and the red light chips R and the blue light chips B form another set of diagonally symmetrical arrangement.

The arrangement mode of the light emitting chips is simple and easy to realize, and the light rays with the three colors of red, green and blue emitted by the three light emitting chips can be collimated by the collimating lens group, so that the uniformity of each light ray after collimation is good, and the light combination is not needed. Meanwhile, since the single light source 13 has a design of a plurality of light emitting chips, high brightness illumination can also be achieved.

It should be emphasized that when the requirement of the projection image on a certain color is high, the light emitting chips corresponding to the color light can be added appropriately, and the light emitting chips are arranged in a diagonally symmetrical manner.

For example, referring to fig. 4, the green light chips G in the above example are provided in two. On the basis, two green light chips G, a single blue light chip B and a single red light chip R can form two groups of diagonally symmetrical distribution (or centrosymmetric arrangement) around the optical axis of one collimating lens group, so that the uniformity of light rays of each color is better after collimation.

Specifically, the two green light chips G are symmetrically arranged and can mutually compensate opposite angles, so that the uniformity of the green light chips G after being collimated by the collimating lens group is better, and the uniformity of the green light chips G can reach more than 90%. The red light chip R and the blue light chip B are in off-axis collimation, but are in diagonally symmetrical distribution, and the uniformity after collimation is not as good as that of green light emitted by the green light chip, but can reach 75% -85%, so that the requirement of human eyes on viewing can be completely met.

In some examples of the present application, referring to fig. 3, the collimating lens set includes a first collimating lens 14 and a second collimating lens 15 disposed along the same optical axis at intervals, wherein the second collimating lens 15 includes at least one aspheric surface, optical powers of the first collimating lens 14 and the second collimating lens 15 are positive, and the first collimating lens 14 and the second collimating lens 15 are used for collimating the projection light into parallel light and then emitting the parallel light.

The projection light emitted by the light source module is collimated by the collimating lens group and then passes through the light homogenizing element 12, the light homogenizing element 12 homogenizes the collimated light, the projection light is emitted into the polarizing element 2 after passing through the field lens 11, the polarizing element 2 transmits S light to the beam splitting prism 1, the beam splitting film 9 converts incident light into P light and transmits the P light to the phase retarder 8, and then the P light is transmitted through the first surface 61 of the fourth lens 6 and then reflected to the phase retarder 8 and then to the beam splitting prism 1 by the second surface 62 of the fourth lens 6. In the above process, the light passes through the retarder 8 twice, the light becomes S-light, and then is reflected by the beam splitting prism 1 and passes through the first lens 3, the second lens 4 and the third lens 5 in sequence to reach the exit pupil.

The incident angle of the projection light beam entering the first collimating lens 14 is 60-80 degrees, and the incident angle of the projection light beam entering the second collimating lens 15 after being collimated and emitted by the first collimating lens 14 is 30-60 degrees.

In the above example, the collimating lens group may include two collimating lenses, that is, the first collimating lens 14 and the second collimating lens 15. On this basis, the projection light emitted by the light source 13 can sequentially pass through the first collimating lens 14 and the second collimating lens 15, so that 0-degree parallel light can be emitted, and the collimating effect on the projection light is realized. The projection light collimated by the collimating lens group contains light rays with various wave bands, and the light rays can directly enter the light homogenizing element 12 for homogenizing treatment without light combination.

The two collimating lenses are arranged in the light source module to perform collimation, so that the curvature of each collimating lens is smaller, and the thickness of the collimating lens is smaller. Compared with a single collimating lens, the combined design of the two collimating lenses is smaller than the thickness of the single collimating lens, so that the size of the whole light source module along the thickness direction is reduced, and meanwhile, the manufacturing difficulty of the lens can be reduced.

Optionally, the distance between the light source and the collimating lens group is more than or equal to 0.1mm.

The closer the distance between the light source and the collimating lens group is, the better the light homogenizing effect is.

When the distance between the light source and the collimating lens group is larger than or equal to 0.1mm, the light homogenizing effect is good under the condition of ensuring small volume. And when the distance between the light source and the collimating lens group is smaller than 0.1mm, structural interference may exist, which affects the quality of the final projection picture, thereby causing the viewing experience of the user to be reduced.

In one specific example, referring to fig. 3, the projection display system includes a light source module, a projection optical module, and a projection chip 10. The projection optical module comprises a beam splitting prism 1 and a projection lens group, the projection lens group comprises a first lens 3, a second lens 4, a third lens 5, a fourth lens 6 and a fifth lens 7, the first lens 3, the second lens 4 and the third lens 5 form a lens group and are positioned on one side of an emergent surface 102 of the beam splitting prism 1, the fourth lens 6 is positioned on one side of a first light transmitting surface 103 of the beam splitting prism 1, a phase retarder 8 is arranged between the fourth lens 6 and the first light transmitting surface 103, and the fifth lens 7 and the projection chip 10 are positioned on one side of a second light transmitting surface 104 of the beam splitting prism 1. The light source module comprises a light source 13, and the light source 13 is a four-in-one light source. The light source module and the polarizing element 2 are sequentially positioned on the light incident path of the beam splitter prism 1. The beam-splitting prism 1 comprises a first prism and a second prism which are connected with each other, and a beam-splitting film 9 is arranged between the first prism and the second prism.

Referring to Table 1 below, table 1 shows the optical parameters of the projection display system provided by the above example.

Table 1 optical parameters of projection display system

Performance of	Parameters (parameters)
		Entrance pupil diameter	3.3mm
EFFL	7.0mm
		LCOS size	2.462*2.462mm
Wavelength of	RGB
		TV distortion	<1.1%
Full field of view MTF	>0.5@132lp/mm
		Telecentric	<1.5°
FOV	28°

In order to effectively enhance the optical performance of the projection display system, the optical structure shown in fig. 1 and 3 is utilized, and specific parameters of the projection display system are as follows:

The effective focal length EFFL =7.03 mm of the projection display system, the total length of the system being 8mm x 8mm.

The projection light path portion of the projection display system comprises five spherical lenses of glass material.

Wherein, the surface S6 of the first lens 3 near the beam-splitting prism 1 is a concave surface.

The surface S3 of the second lens 4 near the third lens 5 is a plane, and the surface S4 of the second lens 4 far from the third lens 5 is a convex surface.

Wherein, the two surfaces S1 and S2 of the third lens 5 are convex.

Wherein, the surface S8 of the fourth lens 6 away from the beam splitting prism 1 is convex.

The surface S11 of the fifth lens 7, which is close to the beam-splitting prism 1, is a convex surface, and the surface S10, which is far from the beam-splitting prism 1, is a concave surface.

Further, specific optical parameters of the first lens 3, the second lens 4, the third lens 5, the fourth lens 6 and the fifth lens 7 can be seen in table 2 below.

The performance achieved by the above example is as follows:

Referring to fig. 5, the MTF value of the projection optical system in each view field is higher than 0.55, and the image definition after being projected by the system in each view field is very good. In addition, the whole system has good temperature resistance due to the use of the all-glass material.

Referring to fig. 6, the distortion value of the projection optical system in each view field is smaller than 1.1%, and the distortion of the TV projected by the system in each view field is smaller, so that the requirement of human eyes on distortion can be completely met.

In yet another aspect, the embodiment of the application further provides a wearable device. The wearable device includes a housing and a projection display system as described above.

The wearable device is, for example, AR smart glasses or AR smart helmets.

The specific implementation of the projection display system and the wearable device according to the embodiments of the present application may refer to the embodiments of the light source module, so that the projection display system and the wearable device at least have all the beneficial effects brought by the technical solutions of the embodiments, which are not described in detail herein.

While certain specific embodiments of the application have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the application. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the application. The scope of the application is defined by the appended claims.

Claims

1. A projection optical module, comprising:

The light-emitting device comprises a PBS (phosphate buffered saline) light-splitting prism (1), wherein the PBS light-splitting prism (1) comprises a light-in surface (101), an emergent surface (102), a first light-transmitting surface (103) and a second light-transmitting surface (104);

the PBS beam splitting prism (1) is arranged in a projection light path of the projection lens group, and the PBS beam splitting prism (1) is provided with at least two surfaces which are adjacently arranged with the projection lens group;

the effective focal length EFFL of the projection optical module is 6mm < EFFL <10mm;

a polarizing element (2) is arranged on the light incident path of the PBS beam splitter prism (1), and the polarizing element (2) and the light incident surface (101) are adjacently arranged;

The projection lens group consists of a lens group positioned on one side of the emergent surface (102), a fourth lens (6) positioned on one side of the first light-transmitting surface (103) and a fifth lens (7) positioned on one side of the second light-transmitting surface (104);

a phase retarder (8) is arranged between the first light-transmitting surface (103) and the fourth lens (6), and projection light rays can pass through the phase retarder (8) twice;

The lens group consists of a first lens (3), a second lens (4) and a third lens (5) which are sequentially arranged along the same optical axis, wherein the first lens (3) and the second lens (4) are mutually glued to form a glued lens group, and the glued lens group is positioned between the PBS (polarization beam splitter) prism (1) and the third lens (5);

The effective focal length EFFL ₁ of the first lens (3) is-8 mm < EFFL ₁ < -6mm;

the effective focal length EFFL ₂ of the second lens (4) is 8mm < EFFL ₂ <13mm;

The effective focal length EFFL ₃ of the third lens (5) is 12mm < EFFL ₃ <19mm;

The effective focal length EFFL ₄ of the fourth lens (6) is 5mm < EFFL ₄ <9mm;

The effective focal length EFFL ₅ of the fifth lens (7) is 16mm < EFFL ₅ <23mm.

2. Projection optical module according to claim 1, characterized in that the PBS splitting prism (1) comprises a first prism and a second prism connected to each other, and a splitting film (9) is arranged between the first prism and the second prism.

3. The projection optical module according to claim 1 or 2, wherein the light incident surface (101) is disposed opposite to the light emergent surface (102), the first light transmitting surface (103) is disposed opposite to the second light transmitting surface (104), or

The light incident surface (101) and the light emergent surface (102) are adjacently arranged, and the first light transmitting surface (103) and the second light transmitting surface (104) are adjacently arranged.

4. A projection display system, comprising:

A projection optical module according to any one of claims 1 to 3, which is located on an optical path transmission path of the light source module, and

And the projection chip (10) is positioned on one side of the fifth lens (7) away from the PBS beam splitter prism (1).

5. The projection display system of claim 4, further comprising a field lens (11) between the light source module and the projection optics module;

The field lens (11) is a lens with positive focal power, two surfaces of the field lens (11) are convex surfaces, and the field lens (11) is used for converging the projection light rays to the projection optical module;

the polarizing element (2) is located between the field lens (11) and the PBS (1), and the polarizing element (2) is arranged on the light incident surface (101).

6. The projection display system according to claim 5, further comprising a light homogenizing element (12), wherein the light homogenizing element (12) is located between the light source module and the field lens (11), and wherein the light homogenizing element (12) is a compound lens made of plastic material.

7. The projection display system according to claim 4, wherein the light source module comprises a light source (13) and a collimating lens group, and the collimating lens group is located on an optical path transmission path of the light source (13);

The light source (13) comprises a plurality of light emitting chips (131), the plurality of light emitting chips (131) are arranged to form a target array, the center of the target array is located on the optical axis of the collimating lens group, and the projection light rays emitted by the collimating lens group can be subjected to light homogenizing treatment directly.

8. The projection display system of claim 7, wherein the collimating lens group comprises a first collimating lens (14) and a second collimating lens (15) arranged along the same optical axis and at intervals, wherein the second collimating lens (15) comprises at least one aspheric surface;

the focal power of the first collimating lens (14) and the second collimating lens (15) is positive;

The first collimating lens (14) and the second collimating lens (15) are used for collimating the projection light into parallel light and then emitting the parallel light.

9. A wearable device, comprising:

A housing, and

The projection display system of any of claims 4-8.