TW202305450A - Head mounted display - Google Patents

Abstract

The present disclosure provides a head mounted display including: a display device for emitting image light; a liquid crystal coupler for receiving the image light and adjusting an emitting angle of the image light; an input coupling grating on a side of the liquid crystal coupler away from the display device, the input coupling grating being used for receiving the image light from the liquid crystal coupler, diffracting the image light, and emitting image light diffracted; a waveguide between the input coupling grating and the liquid crystal coupler, the waveguide being used for receiving and transmitting the image light from the input coupling grating; and an output coupling grating for receiving the image light from the waveguide, diffracting the image light, and emitting the image light diffracted. The image light from the output coupling grating is used to form an augmented reality image.

Description

head mounted display

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

A known augmented reality (Augmented Reality, AR) display usually includes four parts: a display system, an input coupling system, a waveguide, and an output coupling system. The image light emitted by the display system is incident into the input coupling system, propagated by the waveguide, and then output from the output coupling system, thereby presenting augmented reality images to the user. When evaluating the display effect of an AR display, two parameters are usually used: field of view (Field of view, FOV) and eye box (eye box). FOV refers to the angle formed by the two edges of the maximum range that an image can present and the eyes. The eye box refers to the maximum range in which the eyeball can move when the image remains clear, that is, if it exceeds the range of the eye box, the image seen by the eyeball will be distorted. Under the conventional architecture, since the near-eye display limits the area of the waveguide and the output coupling system, the FOV and eye box of the AR display will restrain each other, that is, when the area of the AR display is fixed, increasing the FOV will reduce the eye box. In order to increase the eye box, one solution is to use pupil replication (pupil replication) to replicate the output image light, but this solution will lead to scattered or uneven distribution of image light efficiency and a small FOV.

The application provides a head-mounted display, which includes: a display system for emitting image light; a liquid crystal coupler, used to receive the image light and adjust the exit angle of the image light; an input coupling grating, located on the optical path of the image light, for receiving the image light emitted from the liquid crystal coupler, and for diffracting the image light before emitting; a waveguide, the waveguide is arranged between the input coupling grating and the liquid crystal coupler, and is used to receive and transmit the image light emitted by the input coupling grating; an output coupling grating, the output coupling grating is used to receive the image light transmitted by the waveguide, and is used to diffract the image light and emit it, and the image light emitted by the output coupling grating is used to form An augmented reality image.

In the aforementioned head-mounted display, by setting a liquid crystal coupler between the input coupling grating and the display system, the angle at which the image light enters the input coupling grating can be adjusted, thereby changing the angle at which the image light exits from the output coupling grating, Therefore, the eye box is added while keeping the FOV unchanged, 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 to receive a common voltage; The second electrode layer, the second electrode layer includes a plurality of electrode groups insulated from each other, each electrode group includes a plurality of electrode pairs insulated from each other, each electrode pair includes two electrode blocks, each electrode said two electrode blocks in a pair are adapted to receive a deflection voltage of equal magnitude; and A liquid crystal layer, located between the first electrode layer and the second electrode layer, the liquid crystal layer includes a plurality of liquid crystal molecules, the liquid crystal layer is used to receive the image light, and the plurality of liquid crystal molecules are used deflection according to the common voltage and the deflection voltage to control the exit angle of the image light.

The above-mentioned liquid crystal coupler arranges a plurality of electrode pairs in an electrode group, and controls the deflection voltage of each electrode pair, and then controls the deflection of the liquid crystal molecules in the liquid crystal layer corresponding to the electrode group, thereby controlling the exit angle of the image light .

In one embodiment, the electrode blocks in each electrode pair are centrosymmetric with respect to the geometric center of the electrode set.

In one embodiment, each electrode group includes at least two electrode pairs.

In one embodiment, in one of the electrode groups, at least one of the electrode pairs receives the deflection voltage different from the other electrode pairs.

In one embodiment, the display system includes a plurality of pixels, and each pixel emits a sub-ray independently, and each sub-ray is incident on an electrode group of the liquid crystal coupler, so The plurality of sub-rays emitted by the plurality of pixels jointly constitute the image light.

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

In one 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 respectively supplying The electrode block outputs the deflection voltage.

In one embodiment, the liquid crystal coupler changes the exit angle of the image light when it exits the output coupling grating by adjusting the exit angle when the image light exits from the liquid crystal coupler.

In one embodiment, there is a space between the liquid crystal coupler and the waveguide.

The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of them.

Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the description of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application.

In order to further explain the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description of the present application will be given in conjunction with the accompanying drawings and preferred implementation modes.

An embodiment of the present application provides a head-mounted display, which can be used in virtual reality and augmented reality systems. Head-mounted displays may include glasses or other wearable devices that provide users with computer-generated content overlaid on real-world content, such as images or video overlaid on the user's field of view, to achieve an augmented reality effect.

In an embodiment, please refer to FIG. 1 , a head mounted display 100 includes a display system 10 , a liquid crystal coupler 30 , an input coupling grating 50 , a waveguide 70 and an output coupling grating 90 . The display system 10 is used for emitting an image light. The liquid crystal coupler 30 is used to adjust the exit angle θ when the image light exits from the liquid crystal coupler 30 after receiving the image light, and is used to transmit the image light to the input coupling grating 50 . The input coupling grating 50 is used to diffract the image light and output it into the waveguide 70 . The waveguide 70 is used to transmit the diffracted image light to the output 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 it 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 to control the display system 10 to emit image light and control 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 input coupling grating 50 and the output coupling grating 90 for controlling the incoupling and outcoupling of image light. Controller 20 may include storage devices such as hard drive storage, 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 realize various control operations of the head-mounted display 100, such as data transmission operations, operations involving adjustment of components using control signals, and the like.

In an embodiment, the display system 10 can be one or more displays, specifically self-illuminating active devices, such as micro-organic light-emitting diode display panels and micro-light-emitting diode display panels, or liquid crystals that require external light source illumination. Displays, digital micromirror arrays based on MEMS technology or laser beam scanners. The one or more displays can emit an image light according to the image signal transmitted by the controller 20 , or emit continuously changing image light according to the video signal transmitted by the controller 20 . The image light emitted by the display system 10 is parallel light and is vertically incident into the liquid crystal coupler 30 .

In an embodiment, please refer to FIG. 2 and FIG. 5 together, 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 includes a plurality of electrode groups 331 insulated from each other, and each electrode group 331 is used for receiving a deflection voltage. The second electrode layer 33 also includes a substrate 337 for carrying a plurality of electrode groups 331 , and the substrate 337 is 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, and each liquid crystal molecule 351 is deflected according to the common voltage received by the first electrode layer 31 and the deflection voltage received by the electrode group 331. Since the common voltage received by the first electrode layer 31 is the same everywhere, therefore The degree of deflection 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 the image light is irradiated into the liquid crystal layer 35 , the liquid crystal molecules 351 in the liquid crystal layer 35 will be deflected to different degrees according to the degree of deflection. Therefore, the deflection degree of the image light can be controlled by controlling the deflection voltage, thereby adjusting the outgoing angle θ of the image light when it exits the liquid crystal coupler 30 .

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

In an embodiment, each pixel 11 may include one or more active light emitting elements, 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 also include a control circuit for controlling the light-emitting state of the light-emitting element, which can control the intensity of the sub-light emitted by the pixel 11 .

In one embodiment, please refer to FIG. 4 , each electrode group 331 includes a plurality of mutually insulated electrode pairs 333 , and each electrode pair 333 includes two electrode blocks 335 . A plurality of liquid crystal molecules 351 are included between each electrode block 335 and the first electrode layer 31 . The two electrode blocks 335 in each electrode pair 333 are used to receive the same deflection voltage.

In one embodiment, the number of electrode pairs 333 in each electrode group 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 groups 331 will be described as an example below.

In an embodiment, please continue to refer to FIG. 4 , the electrode set 331 includes four electrode pairs 333 , and the electrode block 335 in each electrode pair 333 is centrosymmetric 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 centrosymmetric with respect to the geometric center of the electrode set 331 .

In one embodiment, please refer to FIG. 4 and FIG. 5 together, different deflection voltages are applied to the electrode pairs 333 in the electrode group 331, specifically, no voltage is applied to the two electrode blocks 335a of an electrode pair 333a in the electrode group 331 , apply the same deflection voltage to the electrode block 335 of the other three electrode pairs 333, under the influence of the deflection voltage and the common voltage, the part of the liquid crystal molecules 351 located between the electrode group 331 and the first electrode layer 31 is deflected, wherein the electrode The liquid crystal molecules 351a corresponding to the pair 333a are not deflected, and the liquid crystal molecules corresponding to the remaining three electrode pairs 333 are deflected. When the sub-rays pass through the part of the liquid crystal layer 35 corresponding to the electrode group 331, the transmission directions of the sub-lights are in multiple deflection states The deflection takes place under the influence of different liquid crystal molecules 351 .

In the embodiment of the present application, an electrode group 331 including four electrode pairs 333 is provided, and the same deflection voltage is applied to three electrode pairs 333, and no voltage is applied to one electrode pair 333a, so that the electrode group 331 and the first electrode can be changed. The electric field distribution between the layers 31 causes the multiple liquid crystal molecules 351 in the part of the liquid crystal layer 35 corresponding to the electrode group 331 to deflect to different degrees. Deflection, so as to achieve the effect of changing the exit angle.

In other embodiments, by adjusting the deflection voltage on each electrode pair 333, the overall electric field distribution of the electrode group 331 can be changed, and then the deflection state of the plurality of liquid crystal molecules 351 in the liquid crystal layer 35 can be changed, so that the liquid crystal passing through The sub-beams of layer 35 are deflected in different degrees. In order to deflect sub-beams, at least one electrode pair 333 in an electrode group 331 needs to have a deflection voltage different from that of other electrode pairs 333 . That is, by making a voltage difference between the plurality of electrode pairs 333 , the electric field of the entire electrode group 331 can be changed, thereby deflecting the sub-rays.

In one embodiment, each electrode group 331 can deflect each sub-ray to a different degree, thereby realizing the effect of a lens, so that when the entire image light is output from the liquid crystal coupler 30, the cross section of the image light can be Enlarged or reduced as a whole, and incident into the input coupling grating 50 at a certain angle.

In one embodiment, the image light exits from the liquid crystal coupler 30, passes through the waveguide 70, and then enters the input coupling grating 50. The input coupling grating 50 can be an adjustable liquid crystal Bragg grating, an adjustable micro-electromechanical system grating, an adjustable Bragg gratings or other types of gratings. The in-coupling grating 50 is used to diffract and exit the image light into the waveguide 70 .

In one embodiment, there is an air gap between the liquid crystal coupler 30 and the waveguide 70, so that the image light can reach the waveguide 70 through a longer optical path after exiting the liquid crystal coupler 30, and the image light can have a greater degree of deflection. .

In one embodiment, the input coupling grating 50 is arranged on the side of the waveguide 70 away from the liquid crystal coupler 30, and is attached to the waveguide 70. After receiving the image light, the input coupling grating 50 outputs a diffracted image in a reflective manner. Light. In other embodiments, the input coupling grating 50 may also be disposed on a side of the waveguide 70 close to the liquid crystal coupler 30 , and emit the diffracted image light in a transmission manner after receiving the image light.

In one embodiment, the waveguide 70 can be made of a transparent material such as glass or plastic, and the image light is transmitted to the out-coupling grating 90 by total reflection in the waveguide 70, and the out-coupling grating 90 can be an adjustable liquid crystal Bragg grating, Adjustable MEMS gratings, tunable Bragg gratings, or other types of gratings. The output 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 emitted by the display system 10 .

In one embodiment, the output coupling grating 90 is disposed on the side of the waveguide 70 away from the liquid crystal coupler 30 , and is bonded to the waveguide 70 . The output coupling grating 90 receives the image light and outputs the image light in a reflective manner. At the same time, the output coupling grating 90 can also transmit the natural light on the side away from the waveguide 70 , so that the eye a can simultaneously receive the image light and the natural light transmitted from the output coupling grating 90 .

In one embodiment, the image light emitted by the liquid crystal coupler 30 is incident on the input coupling grating 50 at different angles, so that the input coupling grating 50 outputs the image light at different angles, and after being transmitted by the waveguide 70, exit the output coupling grating 90 at different angles. That is, the transmitted image light can be coupled out from the output coupling grating 90 at different angles by changing the exit angle θ through the liquid crystal coupler 30 under the condition that the FOV of the displayed image remains unchanged. Incident to the eye a, the range of the eye box is expanded, so that the image displayed by the head-mounted display 100 has a wide range of eye boxes, which improves the display effect and is beneficial to avoid the technology that reduces the eye box when the FOV is increased question.

In one embodiment, the image light emitted by the display system 10 includes three primary color lights, and the wavelengths of the three primary color lights are different. , and the final exit angles are also different. The primary color light output to the eye a in each time period can be adjusted to be coupled out at the same exit angle by the method of outputting the three primary color lights according to time intervals. In other embodiments, the output angle of each primary color light from the liquid crystal coupler 30 can also be directly adjusted, so that the three primary color lights output to the eye a are coupled out at the same output angle.

In one embodiment, the head-mounted display 100 further includes a bracket (not shown) for carrying the display system 10, the liquid crystal coupler 30, the input coupling grating 50, the waveguide 70, and the output coupling grating 90. The head-mounted display 100 is fixed to the user's head so that the eye a can receive the image light coupled out by the output coupling grating 90 .

Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, rather than to limit the present invention, as long as within the scope of the spirit of the present invention, appropriate changes made to the above embodiments and changes all fall within the scope of protection of the present invention.

100:Head Mounted Display 10: Display system 11: Pixel 20: Controller 30: LCD coupler 31: The first electrode layer 33: Second electrode layer 331: electrode group 333, 333a: electrode pair 335, 335a: electrode block 337: Substrate 35: Liquid crystal layer 351, 351a: liquid crystal molecules 50: Input coupling grating 70: Waveguide 90: Output coupling grating θ: exit angle a: eyes

FIG. 1 is a schematic diagram of an optical path structure in a head-mounted display in an embodiment of the present application.

FIG. 2 is a cross-sectional view of a liquid crystal coupler in an embodiment of the present application.

FIG. 3 is a working principle diagram of a liquid crystal coupler in an embodiment of the present application.

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

FIG. 5 is a schematic V-V sectional view of the liquid crystal coupler in FIG. 4 .

100:Head Mounted Display

10: Display system

20: Controller

30: LCD coupler

50: Input coupling grating

70: Waveguide

90: Output coupling grating

a: eyes

θ: exit angle

Claims (10)

A head-mounted display, the improvement of which includes: a display system for emitting image light; a liquid crystal coupler, used to receive the image light and adjust the exit angle of the image light; an input coupling grating, located on the optical path of the image light, used to receive the image light emitted from the liquid crystal coupler, and used to diffract the image light and emit it; a waveguide, which is arranged between the input coupling grating and the liquid crystal coupler, for receiving and transmitting the image light emitted by the input coupling grating; An output coupling grating, the output coupling grating is used to receive the image light transmitted by the waveguide, and is used to diffract the image light and emit it, and the image light emitted by the output coupling grating is used to form an augmented reality image . The head-mounted display as described in claim 1, wherein the liquid crystal coupler includes: The first electrode layer is used to receive a common voltage; The second electrode layer, the second electrode layer includes a plurality of electrode groups insulated from each other, each electrode group includes a plurality of electrode pairs insulated from each other, each electrode pair includes two electrode blocks, and the two electrodes in each electrode pair The electrode blocks are used to receive the same deflection voltage; and A liquid crystal layer, located between the first electrode layer and the second electrode layer, the liquid crystal layer includes a plurality of liquid crystal molecules, the liquid crystal layer is used to receive the image light, and the liquid crystal molecules are used to deflect according to the common voltage and the deflection The voltage is deflected to control the exit angle of the image light. The head-mounted display according to claim 2, wherein the two electrode blocks in each electrode pair are center-symmetrical about the geometric center of the electrode group. In the head-mounted display according to claim 2, each electrode group includes at least two electrode pairs. The head-mounted display as claimed in claim 2, wherein, in one of the electrode groups, the deflection voltage received by at least one electrode pair is different from the deflection voltage received by the other electrode pairs. The head-mounted display as described in claim 2, wherein the display system includes a plurality of pixels, and each pixel emits a sub-ray separately, and each sub-ray is incident on an electrode group of the liquid crystal coupler , the plurality of sub-rays emitted by the pixels together constitute the image light. The head-mounted display as described in claim 6, wherein the head-mounted display further includes a controller, the controller is electrically connected to the display system and the liquid crystal coupler, and is used to control the display system to send out the image light, and control the liquid crystal coupler to adjust the exit angle of the image light. The head-mounted display as described in claim 7, 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 respectively supplying - The electrode block outputs the deflection voltage. The head-mounted display as described in Claim 1, wherein the liquid crystal coupler changes the exit angle of the image light when it exits from the output coupling grating by adjusting the exit angle of the image light when exiting from the liquid crystal coupler horn. The head-mounted display as claimed in claim 1, wherein there is an interval between the liquid crystal coupler and the waveguide.

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