Patent Description:
This disclosure relates to an optical module and an optical device, and in particular to an optical engine module and a projection device.

With the advancement of display technology and demand for high technology by consumers, near-eye display (NED) and head-mounted display (HMD) are products with great development potential currently. Applications related to near-eye display technology can be divided into augmented reality (AR) technology and virtual reality (VR) technology currently. As a light field near-eye display (LFNED) has immediate light field information, it can achieve an effect of focusing afterwards, thereby providing image information that has a depth, which can be used in the augmented reality technology and the virtual reality technology of the near-eye display technology.

In general, optical elements such as a polarizing beam splitting element, a micro lens array, and a focusing lens are used in an optical design of an optical engine module of the near-eye display technology, to enable an image beam entering an imaging system to conform to a pupil of the imaging system. However, as spectroscopic characteristics of the polarizing beam splitting element cause beams of different wavebands with a large incident angle to have different penetration rates, therefore, a color shift is likely to occur for the light beams with a large incident angle. Therefore, a decrease in light collection efficiency of the polarizing beam splitting element incident at a large angle or uneven off-axis color may occur when the imaging system requires a field of view above a certain angle, thereby affecting the image quality.

The information disclosed in this background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Furthermore, the information disclosed in the background section does not mean that one or more problems to be resolved by one or more embodiments of the disclosure were acknowledged by a person of ordinary skill in the art. <CIT> relates to reflective fly-eye arrays, compact illuminators for projecting an image, and in particular illuminators that use a reflective fly-eye array (FEA) to enable the uniform illumination of a spatial light modulator such as a Liquid Crystal on Silicon (LCoS) reflective imager. The illuminators use collimation optics, a polarizing beam splitter, and the reflective FEA to convert small aperture unpolarized Light Emitting Diode (LED) input light to polarized light that can uniformly illuminate the spatial light modulator. <CIT> relates to a projection apparatus including an illumination system and a projection imaging system. The illumination system is adapted to emit an illumination beam, and the illumination system includes a light source module and a light shaping module. The light source module is adapted to emit at least one beam. The light shaping module is disposed on the transmission path of the at least one beam. The at least one beam forms an illumination beam after passing through the light shaping module, and the illumination beam has a light imaging matching angle. The light shaping module includes at least one first lens element. The at least one first lens element is disposed on the transmission path of the at least one beam. The projection imaging system is disposed on a transmission path of the illumination beam.

The disclosure provides a projection device with good image quality and resolution.

Other objectives and advantages of the disclosure can be further understood from technical features disclosed in the disclosure.

An optical engine module includes a light source unit, a first diffusion element, a polarizing beam splitting element, a second diffusion element, and a light valve. The light source unit is configured to emit a light beam. The first diffusion element is disposed on a transmission path of the light beam. The polarizing beam splitting element is disposed on the transmission path of the light beam. The first diffusion element is disposed between the polarizing beam splitting element and the light source unit. The second diffusion element has at least one optical surface. The at least one optical surface is configured to reflect and diffuse the light beam, the light beam forms an illumination beam after passing through the second diffusion element, and the illumination beam has an optical image matching angle. The light valve is disposed on a transmission path of the illumination beam. The light valve is configured to convert the illumination beam to an image beam.

The projection device includes the foregoing optical engine module and a projection lens. The projection lens is disposed on a transmission path of the image beam and is configured to project the image beam out of the projection device.

In the following optional features will be provided, which could be combined singularly or in combination with the the projection device as described above.

In one or more embodiments, the first diffusion element may be a first micro lens array or a first diffiiser.

In one or more embodiments, the second diffusion element may comprise a second micro lens array or a second diffuser.

In one or more embodiments, the second diffusion element may further comprise an optical reflective mirror.

In one or more embodiments, the second micro lens array or the second diffuser may be disposed between the optical reflective mirror and the polarizing beam splitting element.

In one or more embodiments, a reflective surface of the optical reflective mirror back may face the polarizing beam splitting element.

In one or more embodiments, the second diffusion element may comprise a microstructure optical film.

In one or more embodiments, one of surfaces of the microstructure optical film may be a curved surface.

In one or more embodiments, the curved surface may have a plurality of micro structures.

In one or more embodiments, the microstructures may be configured to diffuse the light beam.

In one or more embodiments, the microstructure optical film may have a first optical surface and a second optical surface.

In one or more embodiments, the first optical surface may be disposed between the polarizing beam splitting element and the second optical surface.

In one or more embodiments, the first optical surface may be a surface formed with a plurality of micro lens elements.

In one or more embodiments, the second optical surface may be a reflective surface.

In one or more embodiments, the second optical surface may be a curved surface.

In one or more embodiments, the second optical surface may be a flat surface.

In one or more embodiments, the second diffusion element may further comprise an optical lens, preferably disposed between the microstructure optical film and the polarizing beam splitting element.

In one or more embodiments, the microstructure optical film may have a first optical surface.

In one or more embodiments, the first optical surface may be a surface of a micro-mirror array.

In one or more embodiments, the optical engine module may further comprise a quarter wave plate, preferably disposed between the second diffusion element and the polarizing beam splitting element.

The optical image matching angle of the illumination beam matches a viewing angle of the pupil.

Based on the above, the embodiments of the disclosure have at least one of the following advantages. In the embodiment of the disclosure, the projection device and the optical engine module enable the unit optical divergence angle of the multiple sub-beams of the light beam to expand one after another through the configuration of the first diffusion element and the second diffusion element, and may form the multiple sub-illumination beams satisfying the requirements of the optical path in the projection lens. In this way, the projection device can satisfy the requirements of the optical path in the projection lens through the illumination beam formed by the optical engine module, and has good image quality and resolution. In this way, the diffusion angle of the multiple sub-beams of the light beam facing the polarized optical surface of the first surface can be reduced while maintaining the optical image matching angle of the illumination beam. In this way, in view of the characteristics of the coating film on the polarized optical surface of the polarizing beam splitting element facing the first surface, it can be designed to be suitable for beams with a small light diffusion angle, thereby reducing product costs and maintaining the image quality.

Other objectives, features and advantages of the present invention can be further understood from the further technological features disclosed by the embodiments of the present invention wherein there are shown and described preferred embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention.

The drawings illustrate embodiments of the invention and, together with the descriptions, serve to explain the principles of the invention.

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as "top", "bottom", "front", "back" etc., is used with reference to the orientation of the figure(s) being described. The components of the present invention can be positioned in a number of different orientations. As such, the directional terminology is used for purposes of illustration and is in no way limiting. On the other hand, the drawings are only schematic and the size of the components may be exaggerated for clarity. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of "including", "comprising", or "having" and variations thereof herein is meant to encompass the items listed thereafter as well as additional items. Unless limited otherwise, the terms "connected", "coupled", and "mounted" and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. Similarly, the terms "facing", "faces" and variations thereof herein are used broadly and encompass direct and indirect facing, and "adjacent to" and variations thereof herein are used broadly and encompass directly and indirectly "adjacent to". Therefore, the description of "A" component facing "B" component herein may contain the situations that "A" component directly faces "B" component or one or more additional components are between "A" component and "B" component. Also, the description of "A" component "adjacent to" "B" component herein may contain the situations that "A" component is directly "adjacent to" "B" component or one or more additional components are between "A" component and "B" component. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.

<FIG> is a schematic diagram of an optical architecture of a projection device according to an embodiment of the disclosure. <FIG> is a schematic structural diagram of a microstructure in <FIG>. With reference to <FIG>, in the embodiment, a projection device <NUM> is, for example, a near-eye display device, and is configured to be disposed in front of at least one eye of a user. Specifically, as shown in <FIG>, the projection device <NUM> includes an optical engine module <NUM> and projection lenses <NUM>. Specifically, the optical engine module <NUM> includes a light source unit <NUM>, a first diffusion element <NUM>, a polarizing beam splitting element <NUM>, a second diffusion element <NUM>, and a light valve <NUM>. The number of projection lenses <NUM> is illustrated as more than one to exemplarily indicate that multiple lenses for imaging may be included, but the disclosure is not limited thereto, and the number of the projection lenses <NUM> may also be one. In the embodiment, the light source unit <NUM> includes a laser diode (LD), configured to provide a light beam <NUM>. That is, the light beam <NUM> is a laser beam. The laser light-emitting element is, for example, a blue light source, a red light source, and a green light source, but the disclosure is not limited thereto. The light source unit <NUM> also includes a dichroic mirror for penetrating or reflecting colored lights emitted from the blue light source, the red light source, and the green light source.

In addition, in the embodiment, the light valve <NUM> is, for example, a reflective light valve, which may be configured to convert an illumination beam <NUM> to an image beam <NUM>.

More specifically, as shown in <FIG>, in the embodiment, the first diffusion element <NUM>, the polarizing beam splitting element <NUM>, and the second diffusion element <NUM> are disposed on a transmission path of the light beam <NUM>. The first diffusion element <NUM> is disposed between the polarizing beam splitting element <NUM> and the light source unit <NUM>, and is configured to diffuse the light beam <NUM>. The second diffusion element <NUM> has at least one optical surface, and may be configured to reflect and diffuse the light beam <NUM>. For example, the first diffusion element <NUM> includes a first micro lens array <NUM>, and the second diffusion element <NUM> includes a second micro lens array <NUM> and an optical reflective mirror <NUM>. In the embodiment, the at least one optical surface includes a surface of the second micro lens array <NUM> and a surface of the optical reflective mirror <NUM>. In addition, the second micro lens array <NUM> of the second diffusion element <NUM> is disposed between the optical reflective mirror <NUM> and the polarizing beam splitting element <NUM>, and a reflective surface of the optical reflective mirror <NUM> back faces the polarizing beam splitting element <NUM>.

In the embodiment, the polarizing beam splitting element <NUM> has a first surface S1, a second surface S2, a third surface S3, a fourth surface S4, and a polarized optical surface PBS. The first surface S1 and the second surface S2 are opposite to each other, the third surface S3 and the fourth surface S4 are opposite to each other, and the third surface S3 and the fourth surface S4 are connected to the first surface S1 and the second surface S2. As shown in <FIG>, the light beam <NUM> enters the polarizing beam splitting element <NUM> from the first surface S1 after passing through the first diffusion element <NUM>. After that, the light beam <NUM> leaves the polarizing beam splitting element <NUM> via the second surface S2, and is being transmitted to the second diffusion element <NUM>. In addition, a unit optical divergence angle of a sub-beam of the light beam <NUM> underwent diffusion twice via the second micro lens array <NUM> of the second diffusion element <NUM>. Furthermore, the light beam <NUM> may be reflected back to the polarizing beam splitting element <NUM> via the optical reflective mirror <NUM> of the second diffusion element <NUM>. Moreover, the optical engine module <NUM> further includes a quarter wave plate <NUM> disposed between the second diffusion element <NUM> and the polarizing beam splitting element <NUM>. Therefore, a polarization state of the sub-beam of the light beam <NUM> is changed when the sub-beam of the light beam <NUM> is reflected back to the polarizing beam splitting element <NUM>, and it may be transmitted to the light valve <NUM> via reflection by the polarized optical surface PBS of the polarizing beam splitting element <NUM> and after passing through the third surface S3.

Next, as shown in <FIG>, in the embodiment, the light valve <NUM> is configured to transform the illumination beam <NUM> into an image beam <NUM> having multiple sub-image beams. The image beam <NUM> is transmitted to a pupil PL after sequentially passing through the third surface S3, the polarized optical surface PBS, and the fourth surface S4 the polarizing beam splitting element <NUM> and leaving the polarizing beam splitting element <NUM>. For example, in the embodiment, the pupil PL may be an exit pupil of the projection lens <NUM> or a pupil of the eye of the user. The projection device <NUM> may be applied to virtual reality (VR) technology when the pupil PL is the pupil of the eye of the user.

In general, an overall optical shape of the illumination beam <NUM> has to satisfy a specific light-emitting angle range to enable the illumination beam <NUM> formed by the light beam <NUM> after leaving the optical engine module <NUM> to satisfy a required viewing angle range of an optical path in the projection lens <NUM> and to provide a divergence angle range that has to be satisfied when the sub-image beams formed by the projection lens <NUM> are transmitted to the pupil PL. That is, an optical image matching angle of the illumination beam <NUM> matches a viewing angle of the pupil PL.

Furthermore, in the embodiment, the first diffusion element <NUM> and the second diffusion element <NUM> may be configured to adjust uniformity and optical shape of multiple sub-beams of the light beam <NUM>. An etendue of a sub beam of at least one beam <NUM> becomes larger and has a uniformed optical shape after the at least one beam <NUM> passes through the first diffusion element <NUM> and the second diffusion element <NUM>. In this way, the multiple sub-beams of the at least one beam <NUM> may form an illumination beam <NUM> having the optical image matching angle via the first diffusion element <NUM> and the second diffusion element <NUM>.

In the embodiment, for example, the first micro lens array <NUM> has multiple microstructures MS or the second micro lens array <NUM> has multiple microstructures MS, as shown in <FIG>. The microstructures MS correspond to the sub-beams, and may diffuse the unit optical divergence angle of the sub-beams to form multiple sub-illumination beams of the illumination beam <NUM>. In the embodiment, an average width of the multiple microstructures MS is <NUM> micrometers (µm), but the disclosure is not limited thereto, and may be set to <NUM> micrometers (µm) or other values.

In addition, in addition to the micro lens array, the first diffusion element <NUM> and the second diffusion element <NUM> may also include any one of a surface scattering diffuser, a volume scattering diffuser, and a diffraction element to diffuse the unit optical divergence angle of the sub-beams of the light beam <NUM>, so as to form the multiple sub-illumination beams of the illumination beam <NUM>.

For example, the first diffusion element <NUM> and the second diffusion element <NUM> may also use a first diffuser and a second diffuser of the surface scattering diffuser to replace the configuration of the first micro lens array <NUM> and the second micro lens array <NUM>. Surfaces of the first diffuser and the second diffuser has multiple uneven structures, and may diffuse the unit optical divergence angle of the sub-beams, and provide a same function as the microstructures MS of the first micro lens array <NUM> and the second micro lens array <NUM> shown in <FIG>, which are not repeated here.

In this way, the unit optical divergence angle of the multiple sub-beams of the light beam <NUM> may expand one after another after the multiple sub-beams of the light beam <NUM> pass through the first diffusion element <NUM> and the second diffusion element <NUM>, and may form the multiple sub-illumination beams satisfying the requirements of the optical path in the projection lens <NUM>. In addition, since the multiple sub-beams of beam <NUM> sequentially adjust the optical shape via the first diffusion element <NUM> and the second diffusion element <NUM>, a diffusion angle may be adjusted in sections. The first diffusion element <NUM> first performs light diffusion on the multiple sub-beams of the light beam <NUM>, and then the second diffusion element <NUM> performs light diffusion twice on the multiple sub-beams of the light beam <NUM> that are passing back and forth. In this way, the diffusion angle of the multiple sub-beams of the light beam <NUM> on the polarized optical surface PBS facing the first surface S1 may be reduced while maintaining the optical image matching angle of the illumination beam <NUM>. In this way, in view of characteristics of a coating film on the polarized optical surface PBS of the polarizing beam splitting element <NUM> facing the first surface S1, it can be designed to be suitable for the light beam <NUM> with a small light diffusion angle, thereby reducing product costs, and maintaining image quality.

In this way, the illumination beam <NUM> formed by the at least one beam <NUM> via the first diffusion element <NUM> has the optical image matching angle, and the multiple sub-illumination beams configured to provide each of sub-image rays in the illumination beam <NUM> also have a larger field angle, which can satisfy the requirements of the optical path in the projection lens <NUM>, and can satisfy the divergence angle range required by the pupil PL. In this way, the projection device <NUM> can satisfy the requirements of the optical path in the projection lens <NUM> through the illumination beam <NUM> formed by the optical engine module <NUM>, while having good image quality and resolution.

<FIG> is a schematic diagram of an optical architecture of another projection device according to an embodiment of the disclosure. With reference to <FIG>, a projection device 200A of the embodiment in <FIG> is similar to the projection device <NUM> in <FIG>, and differences therebetween are as follows. In the embodiment, a second diffusion element 140A of the projection device 200A includes a microstructure optical film 141A. The microstructure optical film 141A has a first optical surface OS1 and a second optical surface OS2, and at least one optical surface of the second diffusion element 140A includes the first optical surface OS1 and the second optical surface OS2 of the microstructure optical film 141A. The first optical surface OS1 is disposed between the polarizing beam splitting element <NUM> and the second optical surface OS2. The first optical surface OS1 is a surface formed with multiple micro lens elements ML, and the second optical surface OS2 is a reflective surface. Moreover, in the embodiment, the second optical surface OS2 may be a flat surface. The second diffusion element 140A may also include an optical lens LE disposed between the microstructure optical film 141A and the polarizing beam splitting element <NUM> when the second optical surface OS2 is a flat surface. Moreover, in the embodiment, the micro lens elements ML disposed on the first optical surface OS1 may also diffuse the unit optical divergence angle of the sub-beams, and provide the same function as the microstructures MS shown in <FIG>, which are not repeated here. In another embodiment, the first optical surface OS1 is a surface of a micro-mirror array, and the light beam is reflected after reaching the first optical surface OS1, and in this embodiment, the second optical surface OS2 may not be disposed.

In this way, the projection device 200A may also enable the unit optical divergence angle of the multiple sub-beams of the light beam <NUM> to expand one after another through the configuration of the first diffusion element <NUM> and the second diffusion element 140A, and may form the multiple sub-illumination beams satisfying the requirements of the optical path in the projection lens <NUM>, thereby providing similar advantages of the foregoing projection device <NUM>, which are not repeated here.

<FIG> is a schematic diagram of an optical architecture of yet another projection device according to an embodiment of the disclosure. With reference to <FIG>, a second diffusion element 140B of the projection device 200B according to the embodiment in <FIG> is similar to the second diffusion element 140A of the projection device 200A in <FIG>, and differences therebetween are as follows. The second diffusion element 140B includes a microstructure optical film 141B, and a second optical surface OS2 of the microstructure optical film 141B is a curved surface. In addition, the second diffusion element 140B has multiple microstructures, and the microstructures are configured to diffuse the light beam <NUM>. The microstructures may be disposed on the second optical surface OS2 of the microstructure optical film 141B, or be disposed on a first optical surface OS1, and in this embodiment, the first optical surface OS1 is a flat surface. In addition, in the embodiment, the microstructures of the second diffusion element 140B may also diffuse the unit optical divergence angle of the sub-beams, and provide the same function as the microstructures MS shown in <FIG>, which are not repeated here.

In this way, the projection device 200B may also enable the unit optical divergence angle of the multiple sub-beams of the light beam <NUM> to expand one after another through the configuration of the first diffusion element <NUM> and the second diffusion element 140B, and may form the multiple sub-illumination beams satisfying the requirements of the optical path in the projection lens <NUM>, thereby providing similar advantages of the foregoing projection device 200A, which are not repeated here.

In summary, the embodiments of the disclosure have at least one of the following advantages. In the embodiment of the disclosure, the projection device and the optical engine module enable the unit optical divergence angle of the multiple sub-beams of the light beam to expand one after another through the configuration of the first diffusion element and the second diffusion element, and may form the multiple sub-illumination beams satisfying the requirements of the optical path in the projection lens. In this way, the projection device can satisfy the requirements of the optical path in the projection lens through the illumination beam formed by the optical engine module, and has good image quality and resolution. In this way, the diffusion angle of the multiple sub-beams of the light beam facing the polarized optical surface of the first surface can be reduced while maintaining the optical image matching angle of the illumination beam. In this way, in view of the characteristics of the coating film on the polarized optical surface of the polarizing beam splitting element facing the first surface, it can be designed to be suitable for beams with a small light diffusion angle, thereby reducing product costs and maintaining the image quality.

Claim 1:
A projection device, comprising an optical engine module (<NUM>) and a projection lens (<NUM>), the optical engine module (<NUM>), comprising:
a light source unit (<NUM>) configured to emit a light beam (<NUM>);
a first diffusion element (<NUM>) disposed on a transmission path of the light beam (<NUM>);
a polarizing beam splitting element (<NUM>) disposed on the transmission path of the light beam (<NUM>), wherein the first diffusion element (<NUM>) is disposed between the polarizing beam splitting element (<NUM>) and the light source unit (<NUM>);
a second diffusion element (<NUM>) having at least one optical surface (OS1, OS2), wherein the at least one optical surface (OS1, OS2) is configured to reflect and diffuse the light beam (<NUM>), the light beam (<NUM>) passes through the second diffusion element (<NUM>) to form an illumination beam (<NUM>), and the illumination beam (<NUM>) has an optical image matching angle; and
a light valve (<NUM>), disposed on the transmission path of the illumination beam (<NUM>), wherein the light valve (<NUM>) is configured to convert the illumination beam (<NUM>) to an image beam (<NUM>),
wherein the projection lens (<NUM>) is disposed on a transmission path of the image beam (<NUM>) to project the image beam (<NUM>) out of the projection device (<NUM>),
wherein the projection lens (<NUM>) has a pupil (PL), and
wherein the optical image matching angle of the illumination beam (<NUM>) matches a viewing angle of the pupil (PL).