TWI852166B - Micro-projection display device for wearable devices - Google Patents

Abstract

A micro-projection display device for wearable equipment includes a carrier, a light combining unit that integrates three split beams into a combined light, an optical unit for focusing the combined light passing through to form an image, a light emitting unit, and a light output unit. The light emitting unit includes three light emitting elements for emitting the split beams. Each of the light emitting elements and the light combining unit defines a working distance. The light output unit is used to determine the direction of travel of the combined light, scan a visible image point, and project the image point to an eye box of the human eye. In this way, the overall volume is greatly reduced through the function of integrating light beams by the optical unit, and a larger visual range is achieved through the imaging function of the optical unit and the light output unit, thereby improving the comfort when wearing.

Description

Micro-projection display device for wearable devices

The present invention relates to a projection display device, in particular to a micro-projection display device for wearable devices.

Near Eye Display (NED) or Head-Mounted Display (HMD) is a common wearable device on the market. Since wearable devices are worn on the human body, the size and weight become the key to whether they are ergonomic and comfortable. In addition, NED or HMD is a visual display device based on human eye viewing. In a limited space, it has become a major technical challenge to achieve a larger field of view (FOV) and a small size and light weight at the same time.

Referring to FIG. 1 , a head-mounted display device 1 using projection technology is taken as an example. It mainly projects a light beam generating an image onto a reflector 12 through a display 11, and then presents the image to an eye box of the human eye through the reflector 12.

The eye box refers to a region between the reflector 12 and the eyeball. Since the viewing angle is large, the eyeball is allowed to move without affecting the viewing experience. However, the head-mounted display device 1 using projection technology is equipped with the display 11, which is not only more expensive, but also heavier.

Referring to Figure 2, there is another head-mounted display device 2 that uses laser beam scanning technology. It mainly integrates three beams of different colors emitted by three laser diodes 22 into a combined light through a combined mirror 21, and then projects the combined light onto a free-form reflector 24 in a scanning manner through a micro-vibration mirror 23 (MEMS mirror). In this way, a compact light beam passes through the pupil of the human eye from the reflector 24 and forms an image on the retina of the human eye.

The head-mounted display device 2 using laser beam scanning technology is not only low-cost, but also can reduce the size and weight. However, since the laser beam scanning technology forms an image on the retina of the human eye, the position of the pupil will change as long as the eyeball moves, so that the beam cannot pass through the pupil, resulting in a technical problem of being unable to form an image or unclear image formation.

Therefore, patents such as Chinese Patent Publication No. CN111665622, US Patent Publication No. US2016/0166146, and US Patent Publication No. US2017/0276934 all propose a technology that can track the position of the pupil through a detection element so that the light beam can accurately pass through the pupil.

However, since the eyeball reflects light, the accuracy of the detection is affected. Even if the light beam can pass through the pupil, it is still limited by the pupil's aperture and position, and there is a technical problem of extremely small viewing angle.

Therefore, the purpose of the present invention is to provide a micro-projection display device for wearable devices that can significantly reduce the size and expand the viewing angle.

Therefore, the micro-projection display device of the wearable device of the present invention includes a first reflector, which is used to project at least one visible image point to an eye box of the human eye. The micro-projection display device includes a carrier, a light combining unit, an optical unit, a light emitting unit, and a light emitting unit.

The light combining unit is mounted on the carrier and has at least one light input surface and a light output surface. The light combining unit is used to integrate three beams of light of different colors entering from the at least one light input surface into a beam of combined light that passes through the light output surface and travels along a combined light path.

The optical unit includes a first optical lens, which is disposed on the light-combining path and is used to focus the combined light on the light-combining path and generate an image point.

The light-emitting unit is mounted on the carrier and includes three light-emitting elements, each of which is used to emit a separate split light toward the at least one light incident surface and define a working distance with the optical unit along a split light path.

The light output unit is mounted on the carrier and includes a movable micro-vibration mirror, which is arranged on the light combining path and used to determine the direction of travel of the focused light combining and scan the image point that can be reflected by the first reflecting mirror.

The effect of the present invention is that the overall volume is greatly reduced through the function of integrating light beams by the optical unit, and a larger visual range is achieved through the imaging function of the optical unit and the light output unit, thereby improving the comfort when wearing.

3: Wearable devices

31:Mirror frame

32: First reflector

4: Carrier

5: Optical unit

51: Combined light prism

511: Light-entering surface

512: Bright surface

52: Combined light mirror

521: Light-entering surface

522: Bright surface

6: Optical unit

61: First optical lens

62: Second optical lens

63: First optical lens

7: Light-emitting unit

71: Light-emitting element

8: Light emitting unit

81: Micro-mirror

82: Second reflector

X: axis

P: Light spot

P’: Image point

F: Focus

E: Eye-friendly area

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: FIG. 1 is a schematic diagram illustrating a known head-mounted display device; FIG. 2 is a schematic diagram illustrating another known head-mounted display device; FIG. 3 is a schematic diagram illustrating a first embodiment of the micro-projection display device of the present invention installed on a wearable device; FIG. 4 is a schematic diagram of the first embodiment integrating three split beams into a combined light; FIG. 5 is a schematic diagram of the first embodiment focusing imaging; FIG. 6 is a schematic diagram illustrating the first embodiment integrating a visible The image point is projected into the visible range of the human eye; FIG. 7 is a schematic diagram similar to FIG. 4, but the light combination moves from a second reflector to a micro-vibration mirror; FIG. 8 is a schematic diagram illustrating the change of a light combination unit in the first embodiment; FIG. 9 is a schematic diagram similar to FIG. 8, but the light combination unit is different; FIG. 10 is a schematic diagram similar to FIG. 4, but an optical unit is different; FIG. 11 is a schematic diagram illustrating a second embodiment of the micro-projection display device of the present invention; and FIG. 12 is a schematic diagram illustrating a third embodiment of the micro-projection display device of the present invention.

Referring to Figures 3, 4 and 5, an embodiment of the micro-projection display device of the present invention is provided with a wearable device 3. In this embodiment, the wearable device 3 is a head-mounted display device (HMD), comprising a lens frame 31 and a first free-form reflector 32.

The micro-projection display device includes a carrier 4, a light combining unit 5, an optical unit 6, a light emitting unit 7, and a light emitting unit 8.

The carrier 4 is mounted on the lens frame 31.

The light combining unit 5 is mounted on the carrier 4. In the present embodiment, the light combining unit 5 and the first reflector 32 are arranged along an axis X direction, and include a light combining prism 51 (X-CUBE). The light combining prism 51 is a cube, and has three light incident surfaces 511 and a light emitting surface 512 at a 90-degree angle. One of the light incident surfaces 511 is opposite to the light emitting surface 512, and is arranged along the axis X direction with the light emitting surface 512. The remaining two light incident surfaces 511 are respectively connected to one of the light incident surfaces 511. The light combining prism 51 is used to integrate three beams of split light _Ls of different colors entering from the light incident surfaces 511 into a beam of combined light _Lh passing through the light emitting surface 512.

It is worth mentioning that the light-combining prism 51 achieves the purpose of integrating light beams by reflecting light beams of specific wavelengths or allowing light beams of specific wavelengths to pass through two X-shaped coating surfaces.

The optical unit 6 includes a first optical lens 61. In this embodiment, the first optical lens 61 is a focusing lens directly connected to the light emitting surface 512, and is used to focus the combined light _Lh passing through on a combined light path to form an image.

It is worth noting that the light-combining path refers to the path along which the combined light L _h travels, and is not limited to being parallel to the axis X. Furthermore, the first optical lens 61 is not limited to being directly connected to the light-exiting surface 512 , and in other variations of this embodiment, it may also be disposed on the light-combining path, so that the combined light L _h first passes through the light-exiting surface 512 and then passes through the first optical lens 61 .

The light-emitting unit 7 is mounted on the carrier 4 and includes three light-emitting elements 71. Each of the light-emitting elements 71 can be a laser diode (LD) or a light-emitting diode (LED). In the present embodiment, each of the light-emitting elements 71 is a laser diode, which is used to emit respective split light _Ls along a split light path toward respective light incident surfaces 511. The split light _Ls are respectively a red light beam, a blue light beam and a green light beam. Each of the light-emitting elements 71 is spaced apart from the light-combining unit 5 along the split light path.

It is worth noting that the spacing between each light-emitting element 71 and the light-combining unit 5 will vary according to a preset focal point F position, and the thickness and related parameters of the light-combining unit 5 and the optical unit 6.

The light output unit 8 is mounted on the carrier 4 and includes a micro-vibration mirror 81 (MEMS mirror). The micro-vibration mirror 81 is a tiny reflective mirror made based on the micro-electro-mechanical system (MEMS) technology. The movement mode includes two mechanical movements, translation and torsion, which can determine the direction of the light beam and realize image scanning.

In this embodiment, the micro-vibration mirror 81 is used to guide the combined light L _h toward the first reflective mirror 32 and determine the direction of the combined light L _h . The micro-vibration mirror 81 is disposed on the combined light path and between the first reflective mirror 32 and the first optical lens 61 .

It is worth noting that the micro-vibration mirror 81 is a known structure and is not a technical feature of the present invention. Since those with ordinary knowledge in this field can infer the expanded details based on the above description, no further explanation is given.

After the light emitting elements 71 emit the split lights L _s toward the light incident surfaces 511 , the split lights L _s are combined in the light combining prism 51 and integrated into the combined light L _h . At this time, the combined light L _h travels along the axis X direction and passes through the first optical lens 61 from the light emitting surface 512 .

Refer to Figure 5. For the sake of convenience, the imaging principle of the present invention is explained below using only one of the light-emitting elements 71 and the light beam traveling along the axis X direction.

，可以知道，當已知焦距，且變化物距時，可以得到實像。因此，只需調整每一該發光元件71相對於該合光單元5的間距，理論上，就可以如圖5所示， 使一光點P(物)，在一焦點F上聚焦成像，而生成一像點P’。藉此，當該微振鏡81攔阻該合光L_h，並導引該合光L_h朝該第一反射鏡32行進時，同樣可以在行進的過程中，聚焦成像，生成能夠投影至該第一反射鏡32的像點P’。 According to the Gaussian imaging formula:

It can be known that when the focal length is known and the object distance is changed, a real image can be obtained. Therefore, by simply adjusting the distance between each light-emitting element 71 and the light-combining unit 5, in theory, a light point P (object) can be focused and imaged at a focal point F as shown in FIG. 5 to generate an image point P'. Thus, when the micro-vibration mirror 81 blocks the combined light L _h and guides the combined light L _h toward the first reflector 32, it can also be focused and imaged during the process of moving to generate an image point P' that can be projected onto the first reflector 32.

Referring to FIG. 5 and FIG. 6 , when the combined light L _h that can generate the image point P' hits the micro-vibration mirror 81, the direction of the combined light L _h can be controlled by the translation or rotation of the micro-vibration mirror 81, so that the combined light L _h moves toward the first reflector 32. After the combined light L _h is reflected by the first reflector 32, it moves toward the direction of the human eye. In this way, as shown by the single arrow solid line and the double arrow solid line, an eye box E (eye box) is constructed between the first reflector 32 and the human eye and can clearly present the image point P'.

When the micro-vibration mirror 81 guides the combined light L _h to different positions in a time-series scanning manner, the image points P' can be clearly presented in the eye-friendly area E as shown by the single-arrow imaginary line and the double-arrow imaginary line, and a visible image is generated through the image points P' and the phenomenon of visual retention of the human eye.

It is worth noting that, in order to avoid overly complex lines, FIG. 6 only illustrates the optical path related to the eye-pleasing area E through single-arrow imaginary lines and double-arrow imaginary lines, omitting the optical path from the light combining unit 5 to the first reflector 32.

It should be noted that the combined light L _h is not limited to directly moving from the first optical lens 61 toward the direction of the micro-vibration mirror 81. In other variations of the present embodiment, as shown in FIG7 , the combined light L _h can also move toward the direction of the micro-vibration mirror 81 after passing through a second reflector 82. In this way, the light emitting direction of the combined light L _h relative to the carrier 4 is changed, and the installation positions of the micro-vibration mirror 81 and the light combining prism 51 can be changed according to actual practice.

In addition, the first reflector 32 is not limited to being a free-form optical element. In other variations of the present embodiment, it can also be an optical element that has undergone meta-structure treatment. Since those with ordinary knowledge in this field can infer the expanded details based on the above description, no further explanation is given.

It is worth noting that the number of the light-combining prism 51 is not limited to only one. In other variations of this embodiment, it can also be 2 or 3 as shown in FIG. 8 or FIG. 9.

Referring to FIG. 8 , when the light combining unit 5 includes two light combining prisms 51 connected to each other, the light emitting surface 512 and one of the light incident surfaces 511 opposite to the light emitting surface 512 are formed on one of the light combining prisms 51, and the remaining two light incident surfaces 511 are formed on the other light combining prism 51, and are connected to each other at a 90-degree angle.

Referring to FIG. 9 , when the light combining unit 5 includes three light combining prisms 51 connected to each other and arranged in an L-shape, the light incident surface 511 is formed on one of the light combining prisms 51, one of the light emitting surfaces 512 is formed on another light combining prism 51 opposite to the light incident surface 511, and the remaining two light incident surfaces 511 are formed on the remaining other light combining prism 51, and are connected to each other at a 90-degree angle.

Thus, the light beams can be integrated by only one coating surface inside the light-combining prisms 51, which can simplify the manufacturing process of each light-combining prism 51 and improve the yield rate.

It is worth mentioning that in order to avoid overly complex lines, Figures 7 to 10 only use single lines to represent the light path.

In addition, the split light _Ls are not limited to directly passing through the light incident surfaces 511. In other variations of the present embodiment, as shown in FIG10, the optical unit 6 may further include three second optical lenses 62. Each of the second optical lenses 62 is a collimating lens connected to a respective light incident surface 511 for collimating the passing split light _Ls . Thus, the split light _Ls first passes through the second optical lenses 62 and is collimated before passing through the light incident surfaces 511.

Referring to FIG. 11 , a second embodiment of the present invention is substantially the same as the first embodiment, and also includes the carrier 4 (not shown), the light combining unit 5, the optical unit 6, the light emitting unit 7, and the light emitting unit 8. The difference is that: The light combining unit 5 includes a light combining lens 52. The light combining lens 52 has a light incident surface 521 and a light emitting surface 522 that is at a 90-degree angle to the light incident surface 521. The first optical lens 61 is a focusing lens that can be connected to the light emitting surface 521, or spaced from the light emitting surface 521 along the light combining path.

Thus, after the light emitting elements 71 emit the split lights _Ls toward the light incident surface 521, the split lights _Ls will also converge in the light combining lens 52 and be integrated into the combined light _Lh . The combined light _Lh passing through the first optical lens 61 from the light emitting surface 512 will also be focused on the combined light path to form the image point P'.

When the micro-vibration mirror 81 blocks the combined light L _h and guides the combined light L _h toward the first reflector 32, it can also focus and form an image during the process of traveling, generate an image point P' that can be projected onto the first reflector 32, and construct an eye box E (eye box) between the first reflector 32 and the human eye that can clearly present the image point P'.

Referring to FIG. 12 , a third embodiment of the present invention is substantially the same as the first embodiment, and also includes the carrier 4 (not shown), the light combining unit 5 (not shown), the optical unit 6, the light emitting unit 7 (not shown), and the light emitting unit 8. The difference is that: the optical unit 6 includes a first optical lens 63. In this embodiment, the first optical lens 63 is a focusing reflector. Thus, when the combined light L _h is reflected by the first optical lens 63, it will also be focused on the combined light path to form an image, thereby generating the image point P'.

When the micro-vibration mirror 81 blocks the combined light L _h and guides the combined light L _h toward the first reflector 32, it can also focus and form an image during the process of traveling, generate an image point P' that can be projected onto the first reflector 32, and construct an eye box E (eye box) between the first reflector 32 and the human eye that can clearly present the image point P'.

Through the above description, the advantages of the aforementioned embodiments can be summarized as follows:

1. The present invention can construct an eye box E between the first reflector 32 and the human eye through the light combining unit 5 and the light emitting unit 8, which can not only form a clear image in the eye box E, but also achieve a larger visual range.

2. The present invention can integrate the light beam through the light combining unit 5, simplify and shorten the light transmission path, and greatly reduce the overall volume, so that the overall miniaturization is achieved and the space efficiency is improved.

However, the above is only an example of the implementation of the present invention, and it cannot be used to limit the scope of the implementation of the present invention. All simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the patent specification are still within the scope of the patent of the present invention.

32: First reflector

51: Combined light prism

61: First optical lens

71: Light-emitting element

81: Micro-mirror

P’: Image point

E: Eye-friendly area

Claims (9)

A micro-projection display device for a wearable device, the wearable device comprising a first reflector, the first reflector being used to project at least one visible image point onto an eye box of a human eye, the micro-projection display device comprising: a carrier; a light combining unit, mounted on the carrier and having at least one light entrance surface and a light exit surface, the light combining unit being used to integrate three beams of split light of different colors entering from the at least one light entrance surface into a beam of combined light passing through the light exit surface and traveling along a combined light path; an optical unit, comprising a first optical lens, the first optical lens being a focusing reflector and being arranged on the combined light path, the first optical lens being able to reflect the combined light passing through the light exit surface and traveling along the combined light path; light, so that the combined light is focused on the combined light path and generates an image point; a light emitting unit, mounted on the carrier, and including three light emitting elements, each of which is used to emit a separate split light toward the at least one light incident surface, and defines a working distance with the optical unit along a split light path; and a light emitting unit, mounted on the carrier, and including a movable micro-vibration mirror, which is arranged on the combined light path and is used to determine the direction of travel of the combined light after focusing, and scan the image point that can be reflected by the first reflector. The micro-projection display device of the wearable device as described in claim 1, wherein the light combining unit includes at least one light combining prism, the at least one light combining prism has three light incident surfaces and the light emitting surface, and the first optical lens is a focusing lens that can be connected to the light emitting surface. A micro-projection display device for a wearable device as described in claim 2, wherein the light combining unit includes a light combining prism, the light combining prism is a cube, the light emitting surface is opposite to one of the light incident surfaces, and the light incident surfaces form a 90-degree angle. A micro-projection display device for a wearable device as described in claim 2, wherein the light combining unit includes two light combining prisms connected to each other, each of the light combining prisms is a cube, the light emitting surface and one of the light incident surfaces opposite to the light emitting surface are formed on one of the light combining prisms, and the remaining two light incident surfaces are formed on the other light combining prism, and are connected to each other at a 90-degree angle. A micro-projection display device for a wearable device as described in claim 2, wherein the optical unit includes three light-combining prisms connected to each other, each of the light-combining prisms is a cube, the light-emitting surface is formed on one of the light-combining prisms, one of the light-entering surfaces is formed on another light-combining prism opposite to the light-emitting surface, and the remaining two light-entering surfaces are formed on the remaining other light-combining prisms, and are connected to each other at a 90-degree angle. The micro-projection display device of the wearable device as described in claim 2, wherein the optical unit further includes three second optical lenses, each of which is a collimating lens connected to the at least one light incident surface for collimating the split light passing through. The micro-projection display device of the wearable device as described in claim 1, wherein the light combining unit includes a light combining mirror having a light incident surface that is at a 90-degree angle to the light emitting surface, and the first optical lens is a focusing lens that can be connected to the light emitting surface. A micro-projection display device for a wearable device as described in claim 1, wherein each of the light-emitting elements is a laser diode. The micro-projection display device of the wearable device as described in claim 1, wherein the light emitting unit further includes a second reflector, and the second reflector is used to guide the combined light passing through the light emitting surface and the first optical lens toward the micro-vibration mirror.

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