TWI775539B - 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 conventional 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 on the input-coupling system, and after propagating through the waveguide, it is output from the output-coupling system, thereby presenting an augmented reality image to the user. Two parameters, Field of View (FOV) and eye box, are usually used when evaluating the display effect of AR displays. FOV refers to the angle formed by the two edges of the largest range of the image and the eye. The eye box refers to the maximum range that the eyeball can move when the image remains clear, that is, when 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 of the AR display and the eye box 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 the method of pupil replication to replicate the output image light, but this solution will cause the image light efficiency to be scattered or unevenly distributed, and the FOV is small.

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 the exit angle of the image light; an input coupling grating, is located on the optical path of the image light, and is used for receiving the image light emitted from the liquid crystal coupler, diffracting the image light and then outputting; a waveguide, the waveguide is arranged on the input coupling between the grating and the liquid crystal coupler, for receiving and transmitting the image light emitted by the in-coupling grating; an out-coupling grating, the out-coupling grating is used for receiving the image light transmitted by the waveguide, and is used for diffracting the image light and then exiting, and the image light output from the out-coupling grating is used for forming An augmented reality image.

In the aforementioned head-mounted display, by arranging a liquid crystal coupler between the input-coupling grating and the display system, the angle of the image light entering the input-coupling grating can be adjusted, thereby changing the angle of the image light exiting from the output-coupling grating, Therefore, the eye box is increased while the FOV is kept unchanged, and the display effect of the head-mounted display is improved.

In one embodiment, the liquid crystal coupler includes: a first electrode layer for receiving a common voltage; a second electrode layer, the second electrode layer includes a plurality of mutually insulated electrode groups, each of the electrodes The group includes a plurality of mutually insulated electrode pairs, each electrode pair includes two electrode blocks, and the two electrode blocks in each of the electrode pairs are used for receiving deflection voltages with the same voltage magnitude; and a liquid crystal layer, located on the 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 for receiving the image light, and the plurality of liquid crystal molecules are used for according to the common The voltage and the deflection voltage are deflected to control the exit angle of the image light.

In the above-mentioned liquid crystal coupler, a plurality of electrode pairs are arranged in an electrode group, and the deflection voltage of each electrode pair is controlled, thereby controlling the deflection of liquid crystal molecules in the liquid crystal layer corresponding to the electrode group, thereby controlling the outgoing angle of the image light .

In one embodiment, the electrode blocks in each of the electrode pairs are centrosymmetric about the geometric center of the electrode group.

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

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

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

In one embodiment, the head-mounted display further includes a controller, which is 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 outgoing 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 sending the voltage to each of the electrode blocks respectively. 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 of the image light exiting the liquid crystal coupler.

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

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 set

333, 333a: electrode pair

335, 335a: Electrode block

337: Substrate

35: Liquid crystal layer

351, 351a: Liquid crystal molecules

50: Input coupled 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 according to 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 cross-sectional view along V-V of the liquid crystal coupler in FIG. 4 .

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

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 specification of the present application are for the purpose of describing specific embodiments only, and are not intended to limit the present application.

In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose, the following detailed description of the present application is made with reference to the accompanying drawings and preferred embodiments.

Embodiments of the present application provide a head-mounted display, which can be used in virtual reality and augmented reality systems. The head-mounted display may include glasses or other wearable devices for providing the user with computer-generated content overlaid on the real-world content, such as images or videos overlaid on the user's field of view, to achieve an augmented reality effect.

In one embodiment, referring to FIG. 1 , a 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 . Display system 10 is used for Emits an image of light. The liquid crystal coupler 30 is used to adjust the outgoing angle θ when the image light exits from 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 for diffracting the image light and outputting it into the waveguide 70 . The waveguide 70 is used to transmit the diffracted image light to the outcoupling grating 90 . The output coupling grating 90 is used to re-diffract the diffracted image light to form an augmented reality image, which is output to the eye a.

In one embodiment, the head-mounted display 100 further includes a controller 20, the controller 20 is electrically connected with the display system 10 and the liquid crystal coupler 30, and is used for controlling the display system 10 to emit image light and controlling the adjustment of the liquid crystal coupler 30. 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 coupling in and out of the image light. Controller 20 may include storage devices (eg, hard disk drive storage devices), 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 the like.

In one embodiment, the display system 10 may be one or more displays, and may specifically be self-luminous active devices, such as miniature organic light emitting diode display panels and miniature light emitting diode display panels, or may be liquid crystals that require external light source illumination. Display screens, digital micromirror arrays or laser beam scanners based on MEMS technology. The one or more displays can emit an image light according to the image signal transmitted by the controller 20 , or emit a 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 vertically incident on the liquid crystal coupler 30 .

In one 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 and transparent conductive plate for receiving a common voltage. The second electrode layer 33 includes a plurality of mutually insulated electrode groups 331, and each electrode group 331 is used for receiving a deflection voltage. The second electrode layer 33 further 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 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 the image light is irradiated into the liquid crystal layer 35 , different degrees of deflection will occur according to different degrees of deflection of the plurality of liquid crystal molecules 351 in the liquid crystal layer 35 . because This can control the deflection degree of the image light by controlling the deflection voltage, so as to adjust the exit angle θ of the image light when it exits from the liquid crystal coupler 30 .

In one embodiment, please refer to FIG. 3 , the display system 10 includes a plurality of pixels 11 , each pixel 11 individually emits a sub-ray, and the plurality of sub-rays emitted by the plurality of pixels 11 together constitute image light. Each sub-ray is incident on an electrode group 331 and exits from the liquid crystal coupler 30 at an exit angle through a plurality of liquid crystal molecules 351 deflected between the electrode group 331 and the first electrode layer 31 .

In one 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 may be a laser source or a combination of 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-rays 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 deflection voltages of the same magnitude.

In one embodiment, the number of electrode pairs 333 in each electrode group 331 is the same, and the structure of the electrode blocks 335 in each electrode pair 333 is the same. The structure of one of the electrode groups 331 is exemplified below.

In one embodiment, please continue to refer to FIG. 4 , the electrode group 331 includes four electrode pairs 333 , and the electrode block 335 in each electrode pair 333 is center-symmetrical about the geometric center of the electrode group 331 . In other embodiments, the electrode group 331 may further include at least two electrode pairs 333 , and the electrode blocks 335 in each electrode pair 333 are center-symmetrical about the geometric center of the electrode group 331 .

In an 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 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 between the electrode group 331 and the first electrode layer 31 are partially deflected. The part of the liquid crystal molecules 351a corresponding to 333a is not deflected, and the liquid crystal molecules corresponding to the remaining three electrode pairs 333 are deflected. When the sub-ray passes through the part of the liquid crystal layer 35 corresponding to the electrode group 331, the transmission direction of the sub-ray is in a plurality of deflection states. The deflection occurs under the influence of different liquid crystal molecules 351 .

In the embodiment of the present application, by setting an electrode group 331 including four electrode pairs 333, and applying the same deflection voltage to three electrode pairs 333, and applying no voltage to one electrode pair 333a, the electrode group 331 and the first electrode can be changed. The electric field distribution between the layers 31 causes the plurality of liquid crystal molecules 351 in the part of the liquid crystal layer 35 corresponding to the electrode group 331 to be deflected 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 electric field distribution of the electrode group 331 as a whole can be changed, thereby changing the deflection state of the plurality of liquid crystal molecules 351 in the liquid crystal layer 35, so that the liquid crystal molecules 351 pass through the liquid crystal layer 35. The sub-beams of the layer 35 are deflected to different degrees. In order to deflect the 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 causing a voltage difference between the plurality of electrode pairs 333, the electric field of the electrode group 331 as a whole can be changed, so that the sub-beams can be deflected.

In one embodiment, each electrode group 331 can deflect each sub-ray to different degrees, so as to achieve the effect of a lens, so that when the image light is output from the liquid crystal coupler 30 as a whole, the cross-section of the image light can be changed. The whole is enlarged or reduced, and is incident into the incoupling grating 50 at a certain angle.

In one embodiment, the image light is emitted from the liquid crystal coupler 30, and then enters the input coupling grating 50 after passing through the waveguide 70. The input coupling grating 50 may be an adjustable liquid crystal Bragg grating, an adjustable micro-electromechanical system Bragg gratings or other types of gratings. The incoupling 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 exits the liquid crystal coupler 30 through a longer optical path to reach the waveguide 70, and the image light can have a greater degree of deflection .

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

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 outcoupling grating 90 in a total reflection manner in the waveguide 70. The outcoupling grating 90 can be an adjustable liquid crystal Bragg grating, Adjustable micro-electromechanical system gratings, tunable Bragg gratings or other types of gratings. 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 output from the display system 10 .

In one embodiment, the out-coupling grating 90 is disposed on the side of the waveguide 70 away from the liquid crystal coupler 30 and is attached to the waveguide 70 . The out-coupling grating 90 receives the image light and outputs the image light by reflection. At the same time, the out-coupling grating 90 can also transmit natural light on the side away from the waveguide 70 , so that the eye a can receive the image light and the natural light transmitted from the out-coupling grating 90 at the same time.

In one embodiment, the image light emitted through 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 transmission through the waveguide 70, emerge from the outcoupling 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 outgoing angle θ by 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 box, which improves the display effect, and is beneficial to avoid the technology of reducing 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. , the final exit angle is 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 output angle by outputting the three primary color lights according to the time period. In other embodiments, the exit angle of each primary color light output 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 exit 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 in-coupling grating 50, the waveguide 70 and the out-coupling grating 90, and the bracket is also used for The position where 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 with ordinary knowledge in the art should realize that the above embodiments are only used to illustrate the present invention, not to limit the present invention, as long as the above embodiments are appropriately changed within the scope of the essential spirit of the present invention and variations all fall within the scope of protection of the present invention.

100: Head Mounted Display

10: Display system

20: Controller

30: LCD coupler

50: Input coupled grating

70: Waveguide

90: Output coupling grating

a: eyes

θ: exit angle

Claims (9)

A head-mounted display is improved by comprising: a display system for emitting image light; a liquid crystal coupler for receiving the image light and adjusting the exit angle of the image light; an input coupling grating located in the The optical path of the image light is used for receiving the image light emitted from the liquid crystal coupler, and for diffracting the image light and then exiting; a waveguide, the waveguide is arranged between the input coupling grating and the liquid crystal coupler , used to receive and transmit the image light emitted by the input coupling grating; 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 then exit, the output The image light emitted by the coupling grating is used to form an augmented reality image; wherein, the liquid crystal coupler includes: a first electrode layer for receiving a common voltage; a second electrode layer, the second electrode layer includes a plurality of Mutually insulated electrode groups, each electrode group includes a plurality of mutually insulated electrode pairs, each electrode pair includes two electrode blocks, and the two electrode blocks in each electrode pair are used for receiving deflection voltages with the same voltage 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 for receiving the image light, and the liquid crystal molecules are used for receiving the image light according to the common voltage and The deflection voltage is deflected to control the exit angle of the image light. The head-mounted display of claim 1, wherein the two electrode blocks in each electrode pair are center-symmetrical about the geometric center of the electrode group. The head-mounted display of claim 1, wherein each electrode group includes at least two electrode pairs. The head-mounted display of claim 1, wherein, in the electrode group, the deflection voltage received by at least one of the electrode pairs is different from the deflection voltage received by the other electrode pairs. The head-mounted display of claim 1, wherein the display system comprises a plurality of pixels, each of the pixels individually emits a sub-ray, and each of the sub-rays is incident on an electrode group of the liquid crystal coupler , a plurality of the sub-rays emitted by the pixels together constitute the image light. The head-mounted display according to claim 5, wherein the head-mounted display further comprises a controller, the controller is electrically connected with the display system and the liquid crystal coupler, and is used for controlling the display system to emit the image light, and control the liquid crystal coupler to adjust the outgoing angle of the image light. The head-mounted display as claimed in 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 respectively sending each an electrode block outputting the deflection voltage. The head-mounted display of claim 1, wherein the liquid crystal coupler changes the exit of the image light from the outcoupling grating by adjusting the exit angle of the image light from the liquid crystal coupler. horn. The head mounted display of claim 1, wherein there is a space between the liquid crystal coupler and the waveguide.

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