CN112946895B

CN112946895B - Head-mounted display device

Info

Publication number: CN112946895B
Application number: CN202110141682.8A
Authority: CN
Inventors: 郭柏均
Original assignee: Interface Optoelectronics Shenzhen Co Ltd; Interface Technology Chengdu Co Ltd; Yecheng Optoelectronics Wuxi Co Ltd; General Interface Solution Ltd
Current assignee: Interface Optoelectronics Shenzhen Co Ltd; Interface Technology Chengdu Co Ltd; General Interface Solution Ltd
Priority date: 2021-02-02
Filing date: 2021-02-02
Publication date: 2022-09-20
Anticipated expiration: 2041-02-02
Also published as: CN112946895A; TWI770812B; TW202232189A

Abstract

The present invention provides a head-mounted display device, comprising an eye movement tracking module, an adjustable focus imaging module and an image generation module. The eye movement tracking module is used for detecting eye movement of a user to obtain eye movement tracking information. The adjustable focus imaging module includes a plurality of imaging layers in an overlapping configuration. Each of these imaging layers includes a liquid crystal layer and a linear reflective polarizer. The image generating module is used for receiving the image signal and generating a polarized image beam to the adjustable focus imaging module. The image generating module determines that one of the imaging layers is in a reflective state and the other imaging layers are in a transmissive state according to the eye tracking information, so as to reflect the polarized image beam to the viewing position through the imaging layer in the reflective state.

Description

Head-mounted display device

Technical Field

The present invention relates to a Display device, and more particularly, to a Head-Mounted Display (Head-Mounted Display) applied to Virtual Reality (VR).

Background

With the advancement of technology, the conventional flat display device has not been satisfactory for general consumers. In order to provide visual entertainment with more realistic and three-dimensional sense for users, virtual reality becomes a new trend of the current display technology. The principle of virtual reality is to create a virtual space, and each virtual object in the virtual space has a specific distance set to the user.

Currently, a head-mounted virtual reality display device, such as virtual reality glasses, is widely used. The virtual reality glasses can respectively display different images with the visual angle difference to the left eye and the right eye of the user. By making the two eye sight lines intersect to watch a single object, the user can generate stereoscopic impression.

Generally, when an object is watched, human eyes automatically determine the object distance according to head movement and the included angle between two eyes sight lines. Then, the eye further uses the eye muscle to adjust the focal length of the lens, and this action is performed continuously at any time. However, when using virtual reality glasses, the eye muscles are quite fatigued due to the different focal lengths of the optical elements and the virtual objects. Therefore, the user will feel uncomfortable and cannot obtain a good user experience.

Disclosure of Invention

The invention provides a head-mounted display device which can relieve the problem of eye muscle fatigue when a user watches the head-mounted display device.

The invention provides a head-mounted display device which is suitable for being connected with an external electronic device so as to receive an image signal from the external electronic device and display the image signal. The head-mounted display device comprises an Eye Tracking (Eye Tracking) module, a focus-adjustable imaging module and an image generating module. The eye tracking module is used for detecting the eyeball movement of a user so as to acquire eye tracking information. The adjustable focus imaging module includes a plurality of imaging layers in an overlapping configuration. Each of the imaging layers includes a liquid crystal layer and a linear reflective polarizer that is spaced apart from the liquid crystal layer by a viewing distance. The image generation module is electrically connected with the eye movement tracking module and the focusing imaging module. The image generating module is used for receiving the image signal and generating a polarized image light beam to the focus-adjustable imaging module. The image generation module determines one of the imaging layers to be in a reflective state and the other imaging layers to be in a transmissive state according to the eye tracking information, so as to reflect the polarized image beam to the viewing position through the imaging layer in the reflective state.

In an embodiment of the invention, the focus-adjustable imaging module adjusts the imaging layers to be in a reflective state or a transmissive state according to whether the liquid crystal layer of the imaging layers is energized.

In an embodiment of the invention, the liquid crystal layers are Twisted Nematic (TN) type, and a plurality of electrodes corresponding to the liquid crystal layers are sandwiched between adjacent liquid crystal layers of the imaging layers. In the reflective state, the liquid crystal layer of the imaging layer is not energized; and in the transmission state, the liquid crystal layer of the imaging layer is electrified by applying voltages to the corresponding electrodes.

In an embodiment of the invention, the liquid crystal layers are respectively a Vertical Alignment (VA) type or a Horizontal Alignment (HA) type, and a plurality of electrodes corresponding to the liquid crystal layers are sandwiched between the adjacent liquid crystal layers of the imaging layers. In the reflecting state, the liquid crystal layer of the imaging layer is electrified by applying voltages to the corresponding electrodes; and in the transmissive state, the liquid crystal layer of the imaging layer is not energized.

In an embodiment of the invention, the liquid crystal layer of each of the imaging layers is divided into a plurality of blocks, and a plurality of electrodes corresponding to each of the blocks are sandwiched between adjacent liquid crystal layers of the imaging layers, so that a voltage is applied to each of the blocks to be powered on or off, and one of the blocks is determined to be in a reflective state according to the eye tracking information.

In an embodiment of the present invention, in the reflective state, the liquid crystal alignment direction of the liquid crystal layer of the imaging layer is changed to deflect the optical axis of the polarized image beam, and the polarized image beam after the optical axis deflection is reflected by the linear reflective polarizer.

In an embodiment of the invention, the head-mounted display device further includes a beam splitter disposed between the image generating module and the adjustable-focus imaging module, wherein the beam splitter reflects the polarized image beam to the adjustable-focus imaging module and allows the polarized image beam reflected by the adjustable-focus imaging module to pass through.

In an embodiment of the invention, the eye tracking module is an infrared eye tracking module, and the head-mounted display device further includes a hot mirror disposed between the eye tracking module and the viewing position, the hot mirror reflecting an infrared ray generated by the eye tracking module to the viewing position.

In an embodiment of the invention, the head-mounted display device further includes a linear polarizer disposed between the image generating module and the adjustable-focus imaging module, wherein the image generating module generates a natural light image beam, and the natural light image beam passes through the linear polarizer to output a polarized image beam.

In an embodiment of the invention, each of the plurality of imaging layers has a different curvature, and the curvature of each of the plurality of imaging layers is set corresponding to a different focal length from the viewing position.

Based on the above, each imaging layer of the head-mounted display device of the above-described embodiment has a different curvature, and is capable of switching between the reflective state and the transmissive state. Therefore, the head-mounted display device can obtain different focal length values to achieve the purpose of zooming, and further relieve the fatigue of the eye muscles of the user.

The purpose, technical content, features and effects of the present invention will be more readily understood by the following detailed description of the embodiments taken in conjunction with the accompanying drawings.

Drawings

FIG. 1 is a block diagram of a head mounted display device according to an embodiment of the invention;

FIG. 2 is a schematic diagram showing an optical configuration of the head mounted display device of FIG. 1;

FIG. 3 is a schematic optical path diagram illustrating eye tracking performed by the head-mounted display device of FIG. 2;

FIG. 4 is a schematic optical path diagram illustrating image imaging performed by the head-mounted display apparatus of FIG. 2;

FIG. 5 is a schematic diagram illustrating an optical configuration of a head mounted display device according to another embodiment of the invention; and

fig. 6 is a schematic diagram illustrating an optical configuration of a head-mounted display device according to another embodiment of the invention.

Reference numerals:

50 external electronic device

60 eyeball

100. 200, 300 head-mounted display device

110 eye tracking module

120. 320 adjustable focus imaging module

122. 322 imaging layer

122A, 322A liquid crystal layer

122B Linear reflective polarizer

130. 230 image generation module

140 hot mirror

150 spectroscope

B1, B2, B3 Block

E eye movement tracking information

I image

Ir 1-Ir 4 infrared ray

L1-L5 polarized image light beam

L1' Natural light image Beam

Detailed Description

The following embodiments are provided in conjunction with the drawings for detailed description, and the embodiments are only for illustrative purposes and are not intended to limit the scope of the claims of the present invention. For convenience of understanding, the following embodiments are described with the same or similar reference numerals indicating the same or similar elements. One skilled in the art may selectively implement some or all of the features of any of the embodiments, or selectively combine some or all of the features of the embodiments, as may be implemented. It is to be understood that, unless defined otherwise, all technical terms used have the same meaning as understood by those skilled in the art. However, when some terms are described or defined in the embodiments, the description or the definition of the terms is applied to the description or the definition of each embodiment. In addition, directional terms mentioned in the embodiments, for example: "front" or "rear", "left", "right", "upper", "lower", etc., refer only to the orientation of the attached figures. Accordingly, the directional terminology is used for purposes of illustration and is in no way limiting. It should be understood that throughout the description of the embodiments and all claims that follow, "and/or" includes any and all combinations of one or more of the associated listed items.

Fig. 1 is a block diagram of a head-mounted display device according to an embodiment of the invention. Referring to fig. 1, the head-mounted display device 100 is suitable for being connected to an external electronic device 50 to receive an image signal from the external electronic device 50 and display the image signal. For example, the head-mounted display device 100 may be provided with a connector (not shown) or a wireless transmission module (not shown) to connect with the external electronic device 50. Specifically, the connector may support a Universal Serial Bus (USB) or a High Definition Multimedia Interface (HDMI) specification, but not limited thereto. The wireless transmission module may support a wireless network (Wi-Fi) or a Bluetooth (Bluetooth) communication protocol, but not limited thereto. In the present embodiment, the external electronic device 50 is, for example, a mobile phone, a tablet, or a tablet. The head-mounted display device 100 can be a virtual reality glasses for a user to wear, such that an eyeball 60 of the user is located at a viewing position.

The head-mounted display device 100 includes an eye tracking module 110, a focus-adjustable imaging module 120, and an image generating module 130. The eye tracking module 110 is configured to detect an eye movement of the eyeball 60 to obtain an eye tracking information E. For example, the eye-tracking module 110 can measure the position of the fixation point of the eye 60 or the movement of the eye 60 relative to the head (not shown) of the user to realize the eye movement tracking. Accordingly, the eye tracking module 110 can detect whether the eyeball 60 sees a clear image according to the eye tracking information E.

The image generating module 130 is electrically connected between the external electronic device 50, the eye tracking module 110 and the adjustable focus imaging module 120. The image generating module 130 generates a polarized image beam to the adjustable-focus imaging module 120 according to the image signal, and the adjustable-focus imaging module 120 outputs an image I to the eyeball 60.

Fig. 2 is a schematic diagram showing an optical configuration of the head-mounted display device of fig. 1. Referring to fig. 1 and fig. 2 together, an optical configuration of the head mounted display apparatus 100 will be described below. Focus-adjustable imaging module 120 includes a plurality of imaging layers 122 in an overlapping configuration. Five imaging layers 122 are shown, but the number of layers can be increased or decreased as required for focal length adjustment. Each of the imaging layers 122 has a different curvature and can be set to correspond to a different focal length from the viewing position, respectively, to adjust the different focal lengths. Each of the imaging layers 122 includes a liquid crystal layer 122A and a linear reflective polarizer 122B, and the linear reflective polarizer 122B is far away from the viewing position of the eyeball 60 relative to the liquid crystal layer 122A. In the present embodiment, the focus-adjustable imaging module 120 adjusts the imaging layers 122 to a reflective state or a transmissive state according to whether the liquid crystal layer 122A of the imaging layers is powered on. For example, the liquid crystal layers 122A are twisted nematic liquid crystal layers. In the reflective state, the liquid crystal layer 122A of the imaging layer 122 is not energized. In the transmissive state, the liquid crystal layer 122A of the imaging layer 122 is energized.

It is noted that the imaging layer 122 has liquid crystal as the interlayer (liquid crystal layer 122A) and the linear reflective polarizer 122B as the reflective layer. The imaging layer 122 may also sandwich a plurality of transparent electrodes (not shown) corresponding to the liquid crystal layers between the adjacent liquid crystal layers 122A, so as to apply a voltage to the liquid crystal layers 122A. By applying a voltage to the liquid crystal layer 122A, the liquid crystal alignment direction of the liquid crystal layer 122A can be changed to switch between a normal dielectric state (i.e., a transmissive state) and a half-wave plate state (i.e., a reflective state). In another embodiment, the liquid crystal layers 122A may be a vertical alignment type or a horizontal alignment type. In the reflective state, the liquid crystal layer 122A of the imaging layer 122 is energized. In the transmissive state, the liquid crystal layer 122A of the imaging layer 122 is not energized.

In addition to the eye tracking module 110, the adjustable focus imaging module 120 and the image generating module 130, the head-mounted display device 100 may further include a hot mirror 140 and a spectroscope 150. The hot mirror 140 is disposed between the eye tracking module 110 and the viewing position (where the eyeball 60 is located in the figure). The beam splitter 150 is disposed between the image generating module 130 and the adjustable-focus imaging module 120. Although the optical configuration of the head-mounted display apparatus 100 is illustrated as above, the optical configuration can be adjusted by a person skilled in the art according to the requirement, and the invention is not limited thereto.

Fig. 3 is a schematic optical path diagram illustrating eye tracking performed by the head-mounted display device of fig. 2. Referring to fig. 3, in the present embodiment, the eye tracking module 110 may be an infrared eye tracking module, but may also be implemented by other optical or non-optical methods. It can be understood by those skilled in the art that the eye tracking module 110 of the present embodiment may be formed by an infrared light source (not shown) and an infrared image sensor (not shown) and other prior art elements, and will not be described herein again. First, the infrared light source of the eye tracking module 110 emits an infrared Ir1 to the hot mirror 140. Then, the hot mirror 140 reflects the infrared ray Ir2 to the eyeball 60 at the viewing position. Thereafter, the eyeball 60 reflects the infrared ray Ir3 to the hot mirror 140. The hot mirror 140 further reflects the infrared Ir4 to the infrared image sensor of the eye tracking module 110 to obtain eye tracking information E (as shown in fig. 2). In this way, the eye tracking module 110 can track the movement of the eyeball 60.

Fig. 4 is a schematic optical path diagram illustrating image imaging performed by the head-mounted display device of fig. 2. Referring to fig. 4, after the image generating module 130 receives the image signal of the external electronic device 50 (shown in fig. 1), a polarized image light beam L1 is generated to the beam splitter 150. The beam splitter 150 is a half-transmissive half-mirror. Meanwhile, a controller (not shown) of the image generating module 130 determines a focal length suitable for the eyeball 60 according to the eye tracking information E (as shown in fig. 2), and then determines that one of the imaging layers 122 is in a reflective state and the other imaging layers 122 are in a transmissive state. In fig. 4, it is assumed that the imaging layer 122 located in the middle (third layer from top to bottom) is in a reflective state, and the liquid crystal layer 122A of this imaging layer 122 is not energized and is in a half-wave plate state. The liquid crystal layer 122A of the other image forming layer 122 is energized to be in a normal medium state.

The polarized image beam L2 may then pass directly through the liquid crystal layer 122A that is not in the half-wave plate state and the linear reflective polarizer 122B (the two lower image-forming layers 122), and enter the liquid crystal layer 122A that is in the half-wave plate state. When the polarized image light beam L2 passes through the liquid crystal layer 122A in the half-wave plate state, the optical axis of the polarized image light beam L2 is deflected. The polarized image beam L3 after the optical axis deflection is reflected by the linear reflective polarizer 122B and enters the liquid crystal layer 122A in the half-wave plate state. Accordingly, the polarized image beam L3 passes twice through the half-wave plate, and thus enters the beam splitter 150 through the remaining liquid crystal layer 122A that is not half-wave plate and the linear reflective polarizer 122B (the lower two imaging layers 122). Then, the polarized image light beam L4 passing through the beam splitter 150 enters the hot mirror 140. Since the hot mirror 140 may allow visible light to pass through, but reflect infrared rays. Therefore, the polarized image light beam L4 passes through the hot mirror 140, and the polarized image light beam L5 is output from the hot mirror 140 to the eyeball 60 at the viewing position.

It is worth mentioning that each imaging layer 122 has a different curvature and is capable of switching between a reflective state and a transmissive state. Therefore, the focus-adjustable imaging module 120 can apply a voltage to the liquid crystal layer 122A, that is, the reflective layers with different curvatures can be selected to reflect, so as to obtain different focal length values, thereby achieving the purpose of zooming. That is, the head-mounted display device 100 can determine the object focused by the user through the eye tracking module 110, and adjust the optical path focal length correction through the focusing imaging module 120, so as to alleviate the eye muscle fatigue of the user.

Fig. 5 is a block diagram of a head-mounted display device according to another embodiment of the invention. Referring to fig. 4 and fig. 5, compared to the head-mounted display apparatus 100, the head-mounted display apparatus 200 further includes a linear polarizer 260 disposed between the image generating module 230 and the adjustable focus imaging module 120. The image generating module 130 directly outputs the polarized image beam L1 in the polarization state, and the image generating module 230 of the present embodiment generates a natural light image beam L1'. The natural-light image beam L1' passes through the linear polarizer 260 and outputs a polarized image beam L1. For the sake of brevity, only the differences between the embodiment and fig. 4 are described above, and similar elements are denoted by the same or similar reference numerals, and the functions and actions thereof are not repeated herein.

Fig. 6 is a schematic diagram illustrating an optical configuration of a head-mounted display device according to another embodiment of the invention. Referring to fig. 4 and fig. 6, in the head-mounted display device 100, each of the image-forming layers 122 of the focus-adjustable image-forming module 120 is adjusted to be in the reflective state or the transmissive state by turning on or off the entire liquid crystal layer 122A. In the head-mounted display device 300, the liquid crystal layer 322A of each of the imaging layers 322 of the focus-adjustable imaging module 320 can be divided into a plurality of blocks B1, B2, B3, so as to respectively energize or de-energize each of the blocks B1, B2, B3. That is, the head-mounted display device 300 can divide the transparent electrode (not shown) and the liquid crystal layer 322A into a plurality of regions. Therefore, different electric signals can be input into different areas according to requirements to divide the focal length range of the picture when the image is displayed, so that the application can be more flexible, and the speed can be further reduced. So as to determine one of the blocks as the eye muscle fatigue of the user in the reflective state according to the eye tracking information.

For example, the focal length of the different blocks can be adjusted by setting the block B2 in the middle of the liquid crystal layer 322A to be half-wave plate state (reflective state) and the other two blocks B1, B3 to be normal medium state (transmissive state). Although only three blocks are schematically shown in the figure, the number of blocks is not limited. In addition, different regions of different liquid crystal layers 322A that do not overlap at the projection position can also be simultaneously in the reflective state, and different focal ranges are generated for different positions in the image, which is not limited to this.

In summary, each imaging layer of the head-mounted display device of the above embodiments has a different curvature and is capable of switching between a reflective state and a transmissive state. Therefore, the head-mounted display device can select the reflecting layers with different curvatures to reflect, so as to obtain different focal length values, achieve the purpose of zooming, and further relieve the eye muscle fatigue of a user.

The above-described embodiments are merely illustrative of the technical spirit and features of the present invention, and the object of the present invention is to enable those skilled in the art to understand the content of the present invention and to implement the same, while the claims of the present invention are not limited thereto, i.e. all equivalent changes and modifications made in the spirit of the present invention should be covered in the scope of the claims of the present invention.

Claims

1. A head-mounted display device adapted to be connected to an external electronic device for receiving an image signal from the external electronic device and displaying the image signal, the head-mounted display device comprising:

the eye tracking module is used for detecting the eyeball movement of a user to acquire eye tracking information;

a focus adjustable imaging module comprising a plurality of imaging layers in an overlapping configuration, each imaging layer having a different curvature, the curvature of each imaging layer being set corresponding to a different focal length from a viewing position of the user, each imaging layer comprising a liquid crystal layer and a linear reflective polarizer, the linear reflective polarizer being remote from the viewing position relative to the liquid crystal layer; and

and an image generation module electrically connected to the eye tracking module and the focus-adjustable imaging module, for receiving the image signal and generating a polarized image beam to the focus-adjustable imaging module, wherein the image generation module determines one of the imaging layers to be in a reflective state and the other imaging layers to be in a transmissive state according to the eye tracking information, so as to reflect the polarized image beam to the viewing position via the imaging layer in the reflective state.

2. The head-mounted display device of claim 1, wherein the focus-adjustable imaging module adjusts the imaging layer to the reflective state or the transmissive state based on whether a liquid crystal layer of the imaging layer is energized.

3. The head-mounted display device of claim 2, wherein the liquid crystal layer is twisted nematic and the adjacent liquid crystal layers of the imaging layer sandwich a plurality of electrodes corresponding to each liquid crystal layer, wherein in the reflective state, the liquid crystal layers of the imaging layer are not energized; and in the transmission state, the liquid crystal layer of the imaging layer is electrified by applying voltage to the corresponding electrode.

4. The head-mounted display device according to claim 2, wherein the liquid crystal layer is a vertical alignment type or a horizontal alignment type, and a plurality of electrodes corresponding to the respective liquid crystal layers are sandwiched between adjacent liquid crystal layers of the imaging layer, wherein in the reflective state, the liquid crystal layers of the imaging layer are energized by applying a voltage to the corresponding electrodes; and in the transmissive state, the liquid crystal layer of the imaging layer is not energized.

5. The head-mounted display device according to claim 1, wherein the liquid crystal layer of each of the imaging layers is divided into a plurality of blocks, and a plurality of electrodes corresponding to each of the blocks are interposed between adjacent liquid crystal layers of the imaging layers to apply a voltage to each of the blocks to energize the same, so that one of the blocks is determined to be the reflective state based on the eye-tracking information.

6. The head-mounted display apparatus according to claim 1, wherein in the reflective state, a liquid crystal alignment direction of the liquid crystal layer of the imaging layer is changed to deflect an optical axis of the polarized image beam, and the polarized image beam after the optical axis deflection is reflected by the linear reflective polarizer.

7. The head-mounted display apparatus according to claim 1, further comprising a beam splitter disposed between the image generating module and the adjustable-focus imaging module, the beam splitter reflecting the polarized image beam to the adjustable-focus imaging module and passing the polarized image beam reflected by the adjustable-focus imaging module.

8. The head-mounted display device according to claim 1, wherein the eye tracking module is an infrared eye tracking module, and the head-mounted display device further comprises a hot mirror disposed between the eye tracking module and a viewing position, the hot mirror reflecting infrared rays generated by the eye tracking module to the viewing position.

9. The head-mounted display apparatus according to claim 1, further comprising a linear polarizer disposed between the image generation module and the adjustable-focus imaging module, wherein the image generation module generates a natural light image beam, and the natural light image beam passes through the linear polarizer to output the polarized image beam.