CN113406804B

CN113406804B - Head-mounted display

Info

Publication number: CN113406804B
Application number: CN202110801033.6A
Authority: CN
Inventors: 王世育
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: 2021-07-15
Filing date: 2021-07-15
Publication date: 2022-10-18
Anticipated expiration: 2041-07-15
Also published as: CN113406804A; TWI775539B; TW202305450A

Abstract

The present application provides a head mounted display, comprising: a display system for emitting image light; a liquid crystal coupler for receiving the image light and adjusting an exit angle of the image light; the input coupling grating is positioned on one side of the liquid crystal coupler, which is far away from the display system, and is used for receiving the image light emitted from the liquid crystal coupler and diffracting the image light to emit the image light; the waveguide is arranged between the input coupling grating and the liquid crystal coupler and used for receiving and transmitting the image light emitted by the input coupling grating; and the output coupling grating is used for receiving the image light transmitted by the waveguide and emitting the image light after diffracting the image light, and the image light emitted by the output coupling grating is used for forming an image displayed by near eyes.

Description

Head-mounted display

Technical Field

The application relates to the technical field of display, in particular to a head-mounted display.

Background

Current Augmented Reality (AR) displays typically include four parts, a display system, an input coupling system, a waveguide, and an output coupling system. Image light emitted by the display system is incident to the input coupling system, is output from the output coupling system after being propagated through the waveguide, and accordingly, an augmented reality image is presented to a user. Two parameters, namely Field of view (FOV) and eye box (eye box), are usually used to evaluate the display effect of the AR display. The FOV refers to the angle that the two edges of the maximum range an image can assume make with the eye. eye box refers to the maximum range of eye movement when the image is kept clear, i.e. beyond the eye box, the image seen by the eye will be distorted. In the conventional structure, because the near-eye display limits the area of the waveguide and the output coupling system, the FOV and eye box of the AR display are mutually constrained, that is, when the area of the AR display is fixed, increasing the FOV reduces the eye box. In order to increase the eye box, one solution is to use a pupil replication (pupil replication) method to replicate the output image light, but this solution causes image light efficiency dispersion or distribution unevenness and a small FOV.

Disclosure of Invention

The present application provides a head mounted display, comprising:

a display system for emitting image light;

a liquid crystal coupler for receiving the image light and adjusting an exit angle of the image light;

the input coupling grating is positioned on the optical path of the image light, is used for receiving the image light emitted from the liquid crystal coupler and is used for diffracting the image light and then emitting the image light;

the waveguide is arranged between the input coupling grating and the liquid crystal coupler and used for receiving and transmitting the image light emitted by the input coupling grating;

and the output coupling grating is used for receiving the image light transmitted by the waveguide and emitting the image light after diffracting the image light, and the image light emitted by the output coupling grating is used for forming an augmented reality image.

According to the head-mounted display, the liquid crystal coupler is arranged between the input coupling grating and the display system, the angle of image light entering the input coupling grating can be changed, and the angle of the image light exiting from the output coupling grating is changed, so that the eye box is increased under the condition that the FOV is not changed, and the display effect of the head-mounted display is improved.

In one embodiment, the liquid crystal coupler includes:

the first electrode layer is used for receiving a common voltage;

a second electrode layer, wherein the second electrode layer comprises a plurality of electrode groups insulated from each other, each electrode group comprises a plurality of electrode pairs insulated from each other, each electrode pair comprises two electrode blocks, and the two electrode blocks in each electrode pair are used for receiving deflection voltages with the same voltage; and

and the liquid crystal layer is positioned between the first electrode layer and the second electrode layer and comprises a plurality of liquid crystal molecules, the liquid crystal layer is used for receiving the image light, and the plurality of liquid crystal molecules are used for deflecting according to the common voltage and the deflection voltage so as to control the exit angle of the image light.

The liquid crystal coupler controls the emergent angle of image light by arranging a plurality of electrode pairs in an electrode group and controlling the deflection voltage of each electrode pair so as to further control the deflection of liquid crystal molecules in a liquid crystal layer corresponding to the electrode group.

In one embodiment, the electrode blocks in each of the electrode pairs are centered symmetrically about the geometric center of the electrode set.

In one embodiment, each of the electrode sets includes at least two of the electrode pairs.

In one embodiment, in one of the electrode sets, at least one of the electrode pairs receives a different deflection voltage than the other electrode pairs.

In an embodiment, the display system includes a plurality of pixels, each of the pixels individually emits a sub-light, each of the sub-lights is incident on one of the electrode sets of the lc coupler, and a plurality of the sub-lights emitted by the pixels collectively form the image light.

In an embodiment, the head-mounted display further includes a controller electrically connected to the display system and the liquid crystal coupler, and configured to control the display system to emit the image light and control the liquid crystal coupler to adjust an exit angle of the image light.

In an embodiment, the controller is electrically connected to the first electrode layer for outputting the common voltage, and the controller is electrically connected to each of the electrode blocks for outputting the deflection voltage to each of the electrode blocks, respectively.

In one embodiment, the liquid crystal coupler changes the exit angle of the image light exiting the out-coupling grating by adjusting the exit angle of the image light exiting the liquid crystal coupler.

In one embodiment, the liquid crystal coupler is spaced from the waveguide.

Drawings

Fig. 1 is a schematic diagram of an optical path structure in a head-mounted display according to an embodiment of the present disclosure.

Fig. 2 is a cross-sectional view of a liquid crystal coupler according to an embodiment of the present application.

Fig. 3 is a schematic diagram of an embodiment of a liquid crystal coupler.

FIG. 4 is a partial top view of a liquid crystal coupler according to an embodiment of the present application.

FIG. 5 is a schematic cross-sectional view of a liquid crystal coupler according to an embodiment of the present application.

Description of the main elements

Head mounted display 100

Display system 10

Pixel 11

Controller 20

Liquid crystal coupler 30

First electrode layer 31

Second electrode layer 33

Electrode group 331

Electrode

pair

333, 333a

Electrode

blocks

335, 335a

Substrate 337

Liquid crystal layer 35

Liquid crystal molecules

351, 351a

In-coupling grating 50

Waveguide 70

Out-coupling grating 90

Angle of departure theta

Eye a

The following detailed description will further illustrate the present application in conjunction with the above-described figures.

Detailed Description

The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, of the embodiments of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

To further explain the technical means and effects of the present application for achieving the intended purpose, the following detailed description is given to the present application in conjunction with the accompanying drawings and preferred embodiments.

The embodiment of the application provides a head-mounted display which can be used for a virtual reality system and an augmented reality system. The head mounted display may include glasses or other wearable devices for providing computer-generated content overlaid on real world content to the user, such as images or video overlaid on the user's field of view, etc., for augmented reality effects.

In one embodiment, referring to fig. 1, the head mounted display 100 includes a display system 10, a liquid crystal coupler 30, an in-coupling grating 50, a waveguide 70, and an out-coupling grating 90. The display system 10 is adapted to emit an image light. The liquid crystal coupler 30 is used to adjust an exit angle θ at which the image light exits the liquid crystal coupler 30 after receiving the image light, and to transmit the image light to the input coupling grating 50. The in-coupling grating 50 is used to diffract the image light to exit into the waveguide 70. The waveguide 70 is used to transmit the diffracted image light to the out-coupling grating 90. The output coupling grating 90 is used to diffract the diffracted image light again to form an augmented reality image, and output the augmented reality image to the eye a.

In one embodiment, the head mounted display 100 further includes a controller 20, the controller 20 is electrically connected to the display system 10 and the liquid crystal coupler 30, and is used for controlling the display system 10 to emit the image light and controlling the liquid crystal coupler 30 to adjust the exit angle θ of the image light. In other embodiments, the controller 20 may also be electrically connected to the in-coupling grating 50 and the out-coupling grating 90 for controlling the in-coupling and out-coupling of image light. The controller 20 may include a memory device (e.g., a hard drive memory device), one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, graphics processing units, application specific integrated circuits, or other integrated circuits to implement various control operations of the head-mounted display 100, such as data transmission operations, operations involving the use of control signal conditioning components, and so forth.

In one embodiment, the display system 10 may be one or more displays, and may be self-luminous active devices, such as a micro-organic light emitting diode display panel and a micro-light emitting diode display panel, a liquid crystal display panel requiring an external light source for illumination, a digital micromirror array based on mems technology, or a laser beam scanner. The one or more displays may emit an image light according to an image signal transmitted from the controller 20 or emit a continuously varying image light according to a video signal transmitted from the controller 20. The image light emitted from the display system 10 is parallel light and is vertically incident into the liquid crystal coupler 30.

In an embodiment, referring to fig. 2 and fig. 5, the liquid crystal coupler 30 includes a first electrode layer 31, a second electrode layer 33, and a liquid crystal layer 35. The first electrode layer 31 is a continuous, transparent conductive plate for receiving a common voltage. The second electrode layer 33 comprises a plurality of mutually insulated electrode sets 331, each electrode set 331 being adapted to receive a deflection voltage. The second electrode layer 33 further includes a substrate 337 for carrying the plurality of electrode sets 331, the substrate 337 being made of a transparent insulating material.

In one embodiment, the liquid crystal layer 35 is located between the first electrode layer 31 and the second electrode layer 33. The liquid crystal layer 35 includes a plurality of liquid crystal molecules 351, each liquid crystal molecule 351 being deflected according to the common voltage received by the first electrode layer 31 and the deflection voltage received by the electrode group 331, and since the common voltage received by the first electrode layer 31 is the same everywhere, the deflection degree of the liquid crystal molecules 351 in different regions can be adjusted by adjusting the deflection voltage received by each electrode group 331 in the second electrode layer 33. When image light is irradiated into the liquid crystal layer 35, different degrees of deflection occur according to the difference in the degree of deflection of the plurality of liquid crystal molecules 351 in the liquid crystal layer 35. Therefore, the degree of deflection of the image light can be controlled by controlling the deflection voltage, thereby adjusting the exit angle θ at which the image light exits the liquid crystal coupler 30.

In an embodiment, referring to fig. 3, the display system 10 includes a plurality of pixels 11, each pixel 11 individually emits a sub-light, and the sub-lights emitted by the pixels 11 together form image light. Each sub-light is incident into an electrode group 331, and passes through the plurality of liquid crystal molecules 351 deflected between the electrode group 331 and the first electrode layer 31, so as to exit from the liquid crystal coupler 30 at an exit angle.

In one embodiment, each pixel 11 may include one or more active light emitting devices, such as organic light emitting diodes or micro light emitting diodes, or a combination of a laser source or a filter and a backlight. Each pixel 11 may further include a control circuit for controlling the light emitting state of the light emitting element, so as to control the intensity of the sub-light emitted by the pixel 11.

In one embodiment, referring to fig. 4, each electrode set 331 includes a plurality of electrode pairs 333 insulated from each other, and each electrode pair 333 includes two electrode blocks 335. Each electrode block 335 includes a plurality of liquid crystal molecules 351 between the first electrode layer 31. The two electrode blocks 335 in each electrode pair 333 are for receiving the same magnitude of deflection voltage.

In one embodiment, the number of electrode pairs 333 in each electrode set 331 is the same, and the structure of the electrode block 335 in each electrode pair 333 is the same. The structure of one of the electrode sets 331 is exemplified below.

In one embodiment, with continued reference to fig. 4, the electrode set 331 includes four electrode pairs 333, and the electrode blocks 335 in each electrode pair 333 are centered symmetrically with respect to the geometric center of the electrode set 331. In other embodiments, the electrode set 331 may further include at least two electrode pairs 333, and the electrode blocks 335 in each electrode pair 333 are centered symmetrically with respect to a geometric center of the electrode set 331.

In an embodiment, referring to fig. 4 and fig. 5, different deflection voltages are applied to the electrode pairs 333 in the electrode group 331, specifically, no voltage is applied to two electrode blocks 335a of one electrode pair 333a in the electrode group 331, the same deflection voltage is applied to the electrode blocks 335 of the other three electrode pairs 333, under the influence of the deflection voltage and the common voltage, the liquid crystal molecules 351 located between the electrode group 331 and the first electrode layer 31 are deflected, wherein the liquid crystal molecules 351a corresponding to the electrode pairs 333a are not deflected, the liquid crystal molecules corresponding to the other three electrode pairs 333 are deflected, and when the sub-light passes through the part of the liquid crystal layer 35 corresponding to the electrode group 331, the transmission direction of the sub-light is deflected under the influence of the liquid crystal molecules 351 with different deflection states.

In the embodiment of the present application, by providing an electrode group 331 including four electrode pairs 333, applying the same deflection voltage to three electrode pairs 333, and applying no voltage to one electrode pair 333a, the electric field distribution between the electrode group 331 and the first electrode layer 31 can be changed, so that the liquid crystal molecules 351 in the liquid crystal layer 35 corresponding to the electrode group 331 are deflected to different degrees, and when light passes through the liquid crystal layer 35, the light is deflected under the action of the liquid crystal molecules 351, thereby achieving the effect of changing the emission angle.

In other embodiments, the deflection voltage of each electrode pair 333 may be adjusted to change the electric field distribution of the electrode set 331 as a whole, and further change the deflection state of the liquid crystal molecules 351 in the liquid crystal layer 35, so that the sub-light passing through the liquid crystal layer 35 is deflected to different degrees, and in order to deflect the sub-light, the deflection voltage of at least one electrode pair 333 in one electrode set 331 needs to be different from the deflection voltage of the other electrode pairs 333. That is, by providing a voltage difference between the electrode pairs 333, the electric field of the electrode group 331 as a whole can be changed, and the sub-beams can be deflected.

In an embodiment, each electrode set 331 can deflect each sub-light beam to different degrees, thereby achieving a lens effect, such that when the image light is output from the lc coupler 30 as a whole, the cross section of the image light can be enlarged or reduced as a whole, and the image light is incident into the in-coupling grating 50 at a certain angle.

In one embodiment, the image light exits the lc coupler 30, passes through the waveguide 70, and is incident on the in-coupling grating 50, and the in-coupling grating 50 may be an adjustable lc bragg grating, an adjustable mems grating, a tunable bragg grating, or other type of grating. The in-coupling grating 50 is used to diffract and exit the image light into the waveguide 70.

In one embodiment, an air gap is provided between the lc coupler 30 and the waveguide 70, so that the image light can be deflected to a greater extent by exiting the lc coupler 30 and then passing through a longer optical path to the waveguide 70.

In one embodiment, the in-coupling grating 50 is disposed on a side of the waveguide 70 away from the lc coupler 30, and is attached to the waveguide 70, and the in-coupling grating 50 receives the image light and then outputs the diffracted image light in a reflective manner. In other embodiments, the in-coupling grating 50 may be disposed on a side of the waveguide 70 adjacent to the lc coupler 30 to transmit the diffracted image light after receiving the image light.

In one embodiment, the waveguide 70 may be made of a transparent material such as glass or plastic, the image light is transmitted in the waveguide 70 by total reflection into the output coupling grating 90, and the output coupling grating 90 may be an adjustable liquid crystal bragg grating, an adjustable MEMS grating, a tunable bragg grating, or other type of grating. The out-coupling grating 90 couples the image light out of the waveguide 70 and forms an augmented reality image so that the eye a can see the image emerging from the display system 10.

In one embodiment, the output coupling grating 90 is disposed on a side of the waveguide 70 away from the lc coupler 30, and attached to the waveguide 70, and the output coupling grating 90 receives the image light and then outputs the image light in a reflective manner. Meanwhile, the out-coupling grating 90 may also transmit natural light at a side away from the waveguide 70, so that the eye a may simultaneously receive image light and natural light transmitted from the out-coupling grating 90.

In one embodiment, the image light exiting via the lc coupler 30 is incident on the in-coupling grating 50 at different angles, such that the in-coupling grating 50 outputs the image light at different angles, and exits the out-coupling grating 90 at different angles after being transmitted through the waveguide 70. That is, the transmitted image light can be coupled into and out of the eye a from the output coupling grating 90 at different angles by changing the exit angle θ through the liquid crystal coupler 30 without changing the FOV of the displayed image, so as to expand the range of the eye box, so that the image displayed by the head-mounted display 100 has a wide range of eye boxes, thereby improving the display effect and being beneficial to avoiding the technical problem of reducing the eye boxes when the FOV is increased.

In one embodiment, the image light emitted from the display system 10 includes three primary lights, and the three primary lights have different wavelengths, so that the final emission angles are different after the image light propagates through the lc coupler 30, the in-coupling grating 50, the waveguide 70 and the out-coupling grating 90. The primary colors outputted to the eye a at each period can be adjusted to the same exit angle for outcoupling by a method of outputting three primary colors by period respectively. In other embodiments, the exit angle of each primary color light from the liquid crystal coupler 30 can be directly adjusted, so that the three primary color lights output to the eye a are coupled out at the same exit angle.

In an embodiment, the head mounted display 100 further comprises a bracket (not shown) for carrying the display system 10, the liquid crystal coupler 30, the in-coupling grating 50, the waveguide 70 and the out-coupling grating 90, and for fixing the head mounted display 100 to the head of a user in a position where the image light coupled out by the out-coupling grating 90 can be received by the eye a.

It should be understood by those skilled in the art that the above embodiments are only for illustrating the present application and are not used as limitations of the present application, and that suitable modifications and changes of the above embodiments are within the scope of the claims of the present application as long as they are within the spirit and scope of the present application.

Claims

1. A head-mounted display, comprising:

a display system for emitting image light;

the liquid crystal coupler is used for receiving the image light and adjusting the emergent angle of the image light; the liquid crystal coupler includes:

the first electrode layer is used for receiving a common voltage;

a liquid crystal layer between the first electrode layer and the second electrode layer, the liquid crystal layer including a plurality of liquid crystal molecules, the liquid crystal layer receiving the image light, the plurality of liquid crystal molecules deflecting according to the common voltage and the deflection voltage to control an exit angle of the image light;

2. The head-mounted display of claim 1, wherein the two electrode blocks in each of the electrode pairs are centered symmetrically about a geometric center of the electrode group.

3. The head-mounted display of claim 1, wherein at least two of the electrode pairs are included in each of the electrode sets.

4. The head-mounted display of claim 1, wherein at least one of the electrode pairs in an electrode group receives a different deflection voltage than the other electrode pairs.

5. The head-mounted display of claim 1, wherein the display system comprises a plurality of pixels, each of the pixels individually emitting a sub-light, each of the sub-lights being incident on one of the electrode sets of the lc couplers, the plurality of sub-lights emitted by the plurality of pixels collectively constituting the image light.

6. The head-mounted display of claim 5, wherein the head-mounted display further comprises a controller electrically connected to the display system and the liquid crystal coupler for controlling the display system to emit the image light and controlling the liquid crystal coupler to adjust the exit angle of the image light.

7. The head-mounted display of claim 6, wherein the controller is electrically connected to the first electrode layer for outputting the common voltage, and the controller is electrically connected to each of the electrode blocks for outputting the deflection voltage to each of the electrode blocks, respectively.

8. The head-mounted display of claim 1, wherein the liquid crystal coupler changes an exit angle of the image light exiting the out-coupling grating by adjusting the exit angle of the image light exiting the liquid crystal coupler.

9. The head-mounted display of claim 1, wherein the liquid crystal coupler has a spacing from the waveguide.