CN109471258B

CN109471258B - Near-to-eye display device

Info

Publication number: CN109471258B
Application number: CN201710803568.0A
Authority: CN
Inventors: 施智维; 魏仲廷; 郑权得
Original assignee: Coretronic Corp
Current assignee: Coretronic Corp
Priority date: 2017-09-08
Filing date: 2017-09-08
Publication date: 2021-06-22
Anticipated expiration: 2037-09-08
Also published as: CN109471258A

Abstract

A near-to-eye display device comprises a display and a first waveguide element, wherein the first waveguide element comprises a light incident surface, a light emergent surface, a reflection inclined surface and a plurality of light splitting elements. The image light beam provided by the display enters the first waveguide element through the light inlet surface, is reflected by the reflection inclined surface in the first waveguide element and is transmitted to the light splitting elements, and the light splitting elements split the image light beam and leave the first waveguide element through the light outlet surface. The reflection inclined surface has a first reflectance distribution in a first incident angle range and a second reflectance distribution in a second incident angle range. The second incident angle range is higher than the first incident angle range, and the average reflectivity value of the first reflectivity distribution is larger than that of the second reflectivity distribution. The near-eye display device can effectively solve the ghost problem caused by secondary reflection stray light and provide good display quality.

Description

Near-to-eye display device

Technical Field

The present invention relates to a head-mounted display device, and more particularly, to a near-eye display device.

Background

Near Eye Display (NED) can be applied to a Display system of a Head-mounted Display (HMD), and is a next-generation killer-grade product with great development potential. In the related application of the near-eye display technology, the technology can be divided into Augmented Reality (AR) technology and Virtual Reality (VR) technology. For augmented reality technology, related developers are currently dedicated to providing optimal image quality on the premise of light weight and volume of the near-eye display.

In the optical architecture for realizing augmented reality by using a near-eye display, an image beam for display is emitted by a projection device and then reflected by an optical element with semi-reflection and semi-penetration to enter eyes of a user. The light beam for displaying the image and the external environmental light beam can enter the eyes of the user, thereby achieving the display effect of the augmented reality. However, the user often encounters the ghost image of the displayed image during the process of using the conventional near-eye display. That is, the user can view not only the originally intended image but also an unintended image. Therefore, it is one of the important issues to avoid the Ghost image (Ghost image) on the display screen provided by the near-eye display, and to provide the near-eye display with a better viewing range and visual quality so that the near-eye display can provide a good user experience.

The background section is only used to help the understanding of the present invention, and therefore the disclosure in the background section may include some known techniques which do not constitute the knowledge of those skilled in the art. The statements contained in the "background" section do not represent a statement or a problem to be solved by one or more embodiments of the present invention, but are to be understood or appreciated by those skilled in the art prior to the present application.

Disclosure of Invention

Embodiments of the present invention provide a near-eye display device, which can effectively solve the problem of ghosting caused by secondary reflection stray light and provide good display quality.

Other objects and advantages of the present invention will be further understood from the technical features disclosed in the present invention.

To achieve one or a part of or all of the above or other objects, an embodiment of the present invention provides a near-eye display device. A near-eye display device comprising: a display and a first waveguide element. The display is used for providing the image light beam. The first waveguide element comprises a first light incident surface, a first light emergent surface, a reflection inclined surface and a plurality of first light splitting elements, wherein the image light beam enters the first waveguide device through the first light incident surface, and the image light beam is reflected by the reflection inclined surface in the first waveguide device and transmitted to the first light splitting devices, the first light splitting elements split the image beam and leave the first waveguide element through the first light-emitting surface, wherein the reflection inclined plane has a first reflectance distribution in a first incident angle range and a second reflectance distribution in a second incident angle range, wherein the angle of the second incident angle range is higher than the angle of the first incident angle range, and the average value of the reflectance of the first reflectance distribution is larger than the average value of the reflectance of the second reflectance distribution, wherein the first incident angle range and the second incident angle range are each a continuous range of angles.

Another embodiment of the present invention provides a near-eye display device. A near-eye display device comprising: a display and a first waveguide element. The display is used for providing the image light beam. The first waveguide element comprises a first light incident surface, a first light emergent surface, a reflection inclined surface and a plurality of first light splitting elements, wherein the image light beam enters the first waveguide device through the first light incident surface, and the image light beam is reflected by the reflection inclined surface in the first waveguide device and transmitted to the first light splitting devices, the first light splitting elements split the image light beam and leave the first waveguide element through the first light-emitting surface to be transmitted to human eyes, wherein the reflection inclined plane has a first reflectance distribution in a first incident angle range and a second reflectance distribution in a second incident angle range, wherein the surface of each first light splitting element is provided with a first penetration and reflection type coating film which is in a third incidence angle range, the difference between their reflectivities corresponding to the red, blue and green wavelengths is in the range of 5%, wherein the magnitude of the third incident angle range is in the range of 19 degrees to 41 degrees.

Based on the above, the near-eye display device according to the embodiment of the invention has the reflective inclined plane, and the average value of the reflectivity of the reflective inclined plane in the first incident angle range of the lower angle is greater than the average value of the reflectivity in the second incident angle range of the higher angle, so that the situation that the image beam incident on the first waveguide element is reflected twice on the reflective inclined plane can be suppressed, and further, the unexpected light ray enters the projection target can be avoided.

In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

Fig. 1 is a schematic perspective view illustrating a near-eye display device according to an embodiment of the invention.

Fig. 2 is a side view of the near-eye display device of fig. 1.

FIG. 3 is a schematic diagram illustrating polarization directions of an image beam and different waveguide devices according to an embodiment of the invention.

Fig. 4 is a schematic diagram illustrating a prior art image beam incident waveguide device generating ghost light.

Fig. 5 is a schematic diagram illustrating an incident and reflective inclined plane of an image beam according to an embodiment of the invention.

Fig. 6A shows the reflectivity distribution of the reflection slope according to an embodiment of the invention.

Fig. 6B shows the reflectivity distribution of the reflection slope according to another embodiment of the present invention.

Fig. 7 is a schematic view illustrating a reflection condition of a near-eye display device according to an embodiment of the invention on a reflection inclined plane.

Fig. 8 is a schematic diagram illustrating a near-eye display device according to an embodiment of the invention.

Fig. 9A shows a reflectivity distribution diagram of the first light splitting element according to an embodiment of the invention.

Fig. 9B shows a reflectivity distribution diagram of the first light splitting element according to an embodiment of the invention.

Fig. 9C is a diagram illustrating a reflectivity distribution of the first light splitting element according to an embodiment of the invention.

Fig. 10 is a diagram illustrating a reflectivity distribution of the second light splitting element according to an embodiment of the invention.

Detailed Description

The foregoing and other technical matters, features and effects of the present invention will be apparent from the following detailed description of a preferred embodiment, which is to be read in connection with the accompanying drawings. Directional terms as referred to in the following examples, for example: up, down, left, right, front or rear, etc., are simply directions with reference to the drawings. Accordingly, the directional terminology is used for purposes of illustration and is in no way limiting.

Fig. 1 is a schematic perspective view illustrating a near-eye display device according to an embodiment of the invention. Fig. 2 is a side view of the near-eye display device of fig. 1. Referring to fig. 1 and fig. 2, a near-eye display device 100 of the present embodiment includes a first waveguide element 110, a second waveguide element 120, a display 130, and a lens module 140. The display 130 is used to provide the image beam ML. The second waveguide device 120 is disposed on the transmission path PA of the image beam ML and located between the display 130 and the first waveguide device 110. The lens module 140 is disposed between the display 130 and the second waveguide element 120.

In the present embodiment, the first waveguide element 110 is disposed on the transmission path PA of the image light beam ML, and includes a first light incident surface S11, a first light emitting surface S12, and a plurality of first light splitting elements X1, X2, X3, X4, X5, X6, and a reflection inclined surface S13. The inclined reflecting surface S13 is connected to the first incident surface S11, so that a connection region having an included angle α is formed at one end of the first waveguide element 110. The first waveguide element 110 extends along the first direction X, and the first light splitting elements X1, X2, X3, X4, X5, and X6 are arranged along the first direction X, but the number of the light splitting elements is not limited in the present invention. In the embodiment, the first light incident surface S11 and the first light emitting surface S12 are different portions located on the same surface of the first waveguide element 110, but in other embodiments, the first light incident surface S11 and the first light emitting surface S12 may be different surfaces according to practical requirements, which is not limited in the invention.

The second waveguide element 120 includes a second light incident surface S21, a second light emitting surface S22, and a plurality of second light splitting elements Y1, Y2, Y3, and Y4. The second waveguide element 120 extends in the second direction Y, and the second light splitting elements Y1, Y2, Y3, Y4 are aligned in the second direction Y. In the embodiment, the second light incident surface S21 and the second light emitting surface S22 are disposed opposite to each other, but in other embodiments, the second light incident surface S21 may be adjacent to the second light emitting surface S22 according to different disposition positions of the display 130, which is not limited in the disclosure.

In the present embodiment, the first light splitting elements X1, X2, X3, X4, X5, and X6 and the second light splitting elements Y1, Y2, Y3, and Y4 respectively have a half-transmissive half-reflective coating film, and therefore the image light beam ML has an optical effect of being partially transmitted and partially reflected at the positions of the first light splitting elements X1, X2, X3, X4, X5, and X6 and the second light splitting elements Y1, Y2, Y3, and Y4.

The waveguide elements are made of transparent material, transparent plastic or glass, for example. The number of the light splitting elements included in each waveguide element and the distance between adjacent light splitting elements may be designed according to different product requirements, and are not intended to limit the present invention. The number of the first light splitting elements and the number of the second light splitting elements can be the same or different, and the spacing between the adjacent light splitting elements can be the same or different. In this embodiment, an included angle between each light splitting element and the corresponding light incident surface is substantially equal to 30 degrees or within a range of 30 degrees plus or minus 15 degrees, or equal to 45 degrees or within a range of 45 degrees plus or minus 15 degrees, which can be designed according to different product requirements and is not limited by the invention. In an embodiment, the included angles of the light splitting elements may be equal or unequal. In addition, in an embodiment, the reflectivity of each light splitting element can be adjusted according to the incident angle or the wavelength.

In the present embodiment, the display 130 provides the image beam ML, and the display 130 includes, for example, a Digital Light Processing (DLP)^TMDLP for short^TM) The present invention is not limited to image projection systems such as projection systems, Liquid Crystal Display (LCD) projection systems, or Liquid Crystal On Silicon (LCoS) projection systems. In addition, lens module 140 may include one or more lenses or other beam passing elements.

In the present embodiment, the image beam ML may have only a single polarization direction. Referring to fig. 3, fig. 3 is a schematic view illustrating polarization directions of an image beam and different waveguide devices according to an embodiment of the invention. The anti-reflection structure is not shown here for convenience of illustration. For example, the image light beam ML entering the second waveguide element 120 may be light in a P-polarization direction (like the direction of the third direction Z) for the second light splitting elements Y1, Y2, Y3, Y4. In the present embodiment, the extending direction of the first waveguide element 110 is the first direction X, the extending direction of the second waveguide element 120 is the second direction Y, and when the image light beam ML having the P polarization direction exits the second waveguide element 120 and is reflected by the reflection inclined surface S13 to be transmitted in the first waveguide element 110, the polarization direction of the image light beam ML is the S polarization direction (the direction of the second direction Y) with respect to the first light splitting elements X1, X2, X3, X4, X5, and X6 in the first waveguide element 110. Therefore, the respective coatings of the first light splitting elements and the second light splitting elements can be designed corresponding to the image beam ML having a single polarization direction.

Referring to fig. 1 and fig. 2 again, in the present embodiment, the image light beam ML from the image system 130 passes through the lens module 140 along the third direction Z, passes through the lens module 140, enters the second waveguide element 120 through the second light incident surface S21 along the pass path PA, and passes through the second light splitting elements Y1, Y2, Y3, and Y4. In the present embodiment, a part of the image light beam ML is reflected by the second light splitting element Y1 and a part of the image light beam ML passes through the second light splitting element Y1 to propagate along the second direction Y within the second waveguide 120, and the image light beam ML exits the second waveguide 120 along the third direction Z via the second light exit surface S22 after being reflected by the second light splitting elements Y1, Y2, Y3, and Y4.

Referring to fig. 2, in the present embodiment, the first waveguide element 110 and the second waveguide element 120 have a distance d in the third direction Z, and more specifically, the first light incident surface S11 of the first waveguide element 110 and the second light emitting surface S22 of the second waveguide element 120 have a distance d in the third direction Z. The image light beam ML exits the second waveguide element 120 from the second light exiting surface S22, continues to propagate along the third direction Z, enters the first waveguide element 110 from the first light incident surface S11 through the distance d, and is transmitted to the inclined reflective surface S13. The image light beam ML is reflected by the reflection inclined surface S13 and transmitted to the first light splitting elements X1, X2, X3, X4, X5, and X6. The reflection inclined surface S13 has a reflection coating film on its upper surface, for example, and reflects light.

In the present embodiment, the image light beam ML passes through the first waveguide element 110 along the first direction X, and the image light beam ML exits the first waveguide element 110 from the first light exit surface S12 after passing through and reflecting the first light splitting elements X1, X2, X3, X4, X5, and X6, and is projected to the projection target P, such as a pupil or an eye of a user. In one embodiment, the projection target P is an image sensing Device, such as a Charge-coupled Device (CCD) or a Complementary Metal-Oxide-Semiconductor (CMOS) image sensor, for example, which receives the image beam ML.

In the present embodiment, the image beam ML has a corresponding viewing angle at the position where the target P is projected. The viewing angles include, for example, a first viewing angle in a first direction X and a second viewing angle in a second direction Y. In the present embodiment, the size of the first viewing angle is determined according to the number of the first light splitting elements in the first waveguide element 110, the distance from the first light splitting element to the last light splitting element in the first light splitting element, or the distance between two adjacent light splitting elements, for example. Similarly, the size of the second viewing angle is determined by the number of the second light splitting elements in the second waveguide element 120, the distance from the first light splitting element to the last light splitting element in the second light splitting element, or the distance between two adjacent light splitting elements, for example. In the present embodiment, the viewing angle in the diagonal direction of the projection target P may be determined according to a first viewing angle in the first direction X and a second viewing angle in the second direction Y, and may range from about 20 degrees to about 60 degrees. The diagonal viewing angle can be designed according to different product requirements, and is not intended to limit the invention.

Based on the above, the image light beam ML enters the first waveguide element 110 and the second waveguide element 120, but when the image light beam ML is incident on the reflection inclined surface S13 at a small angle, an unexpected reflected light beam is easily generated, for example, the reflection inclined surface S13 is incident at a small angle in the first waveguide element 110, and thus more than one reflection light beam occurs on the reflection inclined surface S13.

Referring to fig. 4, fig. 4 is a schematic diagram illustrating a background image beam incident on a waveguide device to generate ghost light. In the present embodiment, the waveguide element 410 is taken as an example. In this embodiment, the waveguide element 410 is exemplified by the structure of the first waveguide element 110. The waveguide device 410 includes an incident surface S41 and an exit surface S42, and the incident surface S41 and the exit surface S42 are located on the same surface of the waveguide device 410 but at different positions. The waveguide element 410 further includes a slanted surface S43. After the image beam ML1 and the image beam GL enter the waveguide device 410 through the light incident surface S41, the inclined surface S43 has a reflective coating for reflecting the image beam ML1 and the image beam GL such that the image beams ML1 and GL travel in the waveguide device 410. The waveguide element 410 further includes a plurality of first light splitting elements X1, X2, X3, X4, X5, X6, so that the image light beams ML1 and the image light beams GL exit the waveguide element 410 through the light exit surface S42. The image light beam ML1 is a light beam incident on the inclined surface S43 at a large angle, and is reflected once only on the inclined surface S43, and then travels through the waveguide device 410 and is reflected by the first light splitting devices X1, X2, X3, X4, X5, and X6 to leave the waveguide device 410, so as to generate the display light beams I1, I2, and so on, for example, the display light beams I1 and I2 are transmitted to the user' S eyes, and the user sees a virtual image. Here, the larger angle is, for example, greater than 30 degrees or greater than 45 degrees, the present invention is not limited thereto, and those skilled in the art can determine the incident angle range suitable for the inclined surface S43 not to generate more than one reflection according to the actual situation.

On the other hand, the image light beam GL is incident on the region close to the light incident surface S41 and the inclined surface S43, and therefore is reflected more than once on the inclined surface S43, as shown in fig. 4, the image light beam GL is transmitted through the waveguide 410 after being reflected twice on the inclined surface S43, and then reflected by the first light splitting elements X1, X2, X3, X4, X5, and X6 to leave the waveguide 410 to generate a ghost light beam, for example, G1. The ghost beam G1 is referred to herein as ghost beam because the image beam GL having the secondary reflection generates light rays with unexpected viewing angles, and these unexpected light rays continuously travel in the waveguide 410 and are reflected by the first light splitting elements X1, X2, X3, X4, X5, and X6 to enter the eyes of the user. In this case, the user can view not only the originally intended image but also an unintended image. Therefore, the secondary reflected light can make the user feel the ghost image in the image picture in the process of using the near-eye display.

In contrast, in order to reduce the occurrence of ghost in the image, in an embodiment of the present invention, the reflectivity of the inclined reflective surface S13 of the first waveguide element 110 has a first reflectivity distribution in the first incident angle range and a second reflectivity distribution in the second incident angle range. In this embodiment, the angle of the second incident angle range is higher than that of the first incident angle range, and the average reflectivity value of the first reflectivity distribution is larger than that of the second reflectivity distribution. Here, the first incident angle range and the second incident angle range are each a continuous angle range.

First, referring to fig. 6A and 6B in conjunction with fig. 5, fig. 5 is a schematic diagram illustrating an incident and reflective inclined plane of an image beam according to an embodiment of the present invention. Fig. 6A shows the reflectivity distribution of the reflection slope according to an embodiment of the invention. Fig. 6B shows the reflectivity distribution of the reflection slope according to another embodiment of the present invention. In the present embodiment, the reflectance of the reflection inclined surface S13 varies with the change in reflectance for light beams of different wavelengths. The

curves

610, 620, 630 in fig. 6A are the change of the reflectance of the reflection inclined plane S13 with respect to the incident angle for blue (e.g., 465nm wavelength), green (e.g., 525nm wavelength) and red (e.g., 616nm wavelength) light, respectively. Fig. 6B shows that the reflection inclined plane S13 has a different reflectivity from the embodiment of fig. 6A, and the

curves

610, 620, and 630 in fig. 6B are respectively the variation of the reflectivity of the reflection inclined plane S13 with respect to the incident angle of blue (e.g., 465nm wavelength), green (e.g., 525nm wavelength) and red (e.g., 616nm wavelength) light. The incident angle is an angle at which the image beam is incident on the reflection inclined surface S13.

In fig. 6A, the reflectance distribution in the first incident angle range IA1 is referred to as a first reflectance distribution, and the reflectance distribution in the second incident angle range IA2 is referred to as a second reflectance distribution. And the first incident angle range IA1 and the second incident angle range IA2 are continuous angle ranges. The range of the first reflectance distribution is, for example, in the range of 20% to 50%. The range of the second reflectance distribution is, for example, in the range of 0% to 10%. In fig. 6B, the range of the first reflectance distribution is, for example, in the range of 40% to 70%. The range of the second reflectance distribution is, for example, in the range of 0% to 5% or in the range of 0% to 10%. In other embodiments, the first reflectance distribution may fall within a range of 20% to 70% and the second reflectance distribution may fall within a range of 0% to 10% depending on the different reflectances of the reflection slope S13, for example.

Referring back to fig. 5, the image beam ML enters the first waveguide 110 through the second waveguide 120 along the optical axis OA, which is the same direction as the third direction Z in the present embodiment. The image light beam ML is a diffused light beam having a field of view (FOV), and in fig. 5, the light rays MLB1 and MLB2 are used to show that the angle between the optical axis and the edge light rays of the field of view of the image light beam ML in the first waveguide element 110 is β, and the included angle formed by the inclined reflective surface S13 and the first light incident surface S11 is α, so that the incident angle of the inclined reflective surface S13 is within the range of α plus or minus β for the light rays that mainly affect the viewing experience. In the present specification, the incidence angle of the image beam ML is an angle of incidence of the reflection inclined surface S13, that is, an angle between the optical axis OA and a normal line of the reflection inclined surface S13.

For example, the included angle α is 30 degrees and the included angle β is 13 degrees, so that it is expected that the incident angle of the light rays mainly entering the eyes of the user at the reflective inclined surface S13 falls within a range of 17 degrees to 43 degrees. On the other hand, if the light ray is reflected for the second time by the inclined reflective surface S13, the incident angle of the second reflection is usually larger, for example, larger than 70 degrees (see fig. 4). Therefore, in the present embodiment, the range of the first incident angle range IA1 is, for example, greater than or equal to 17 degrees and less than or equal to 43 degrees, and the range of the second incident angle range IA2 is, for example, greater than or equal to 70 degrees and less than or equal to 85 degrees. In the practice of the present invention, since the light is reflected by almost one hundred percent at a 90 degree incident angle, the reflectance of the inclined reflective surface S13 in actual manufacturing is only 5% at a maximum angle of substantially 85 degrees.

Returning to fig. 6A, in the first incident angle range IA1, the reflectance of the first reflectance distribution corresponding to the green wavelength 620 is smaller than the reflectance thereof corresponding to the blue wavelength 610, and the reflectance of the first reflectance distribution corresponding to the red wavelength 630 is smaller than the reflectance thereof corresponding to the green wavelength 620. In addition, the reflectances corresponding to the blue wavelength 610, the green wavelength 620, and the red wavelength 630 tend to increase with increasing angle values in the first incident angle range IA 1.

In the present embodiment, the range of the first reflectance distribution, which is the reflectance of each of the blue, green and

red wavelengths

610, 620 and 630, falls within the range of 20% to 50%. Here, the average reflectance of the reflectance for the blue wavelength 610 in the first incident angle range IA1 is about 36%, the average reflectance of the reflectance for the green wavelength 620 in the first incident angle range IA1 is about 30%, and the average reflectance of the reflectance for the red wavelength 630 in the first incident angle range IA1 is about 23%.

In addition, the reflectance in the second incident angle range IA2 is designed to be less than 10% regardless of the reflectance corresponding to the blue, green, and

red wavelengths

610, 620, and 630, and in the present embodiment, the second reflectance distribution falls within a range of 0% to 5%. Specifically, the average reflectance of the reflectance corresponding to the blue wavelength 610 in the second incident angle range IA2 is about 3%, the average reflectance of the reflectance corresponding to the green wavelength 620 in the second incident angle range IA2 is only about 1%, and the average reflectance of the reflectance corresponding to the red wavelength 630 in the second incident angle range IA2 is also about 1%. Therefore, the reflectance and the average reflectance in the first incident angle range IA1 are greater than those in the second incident angle range IA2 for any color. In this embodiment, the range of the second reflectance distribution may even fall within the range of 0% to 5%.

Fig. 6B is similar to the embodiment of fig. 6A, with the difference that the average value of the reflectance within the first incident angle range IA1 of the reflection inclined plane of the embodiment of fig. 6B is designed to be higher than that of the embodiment of fig. 6A. The range of the second reflectivity distribution can be selected to fall within a range of 0% to 10%, or 0% to 5%, but the invention is not limited thereto. In the present embodiment, the range of the first incident angle range IA1 is equal to or greater than 17 degrees and equal to or less than 43 degrees, and the range of the second incident angle range IA2 is also equal to or greater than 70 degrees and equal to or less than 85 degrees. In the present embodiment, the range of the first reflectance distribution, which is the reflectance of each of the blue, green and red wavelengths 610 ', 620 ', 630 ', falls within the range of 40% to 90%. Here, the average reflectance of the reflectance corresponding to the blue wavelength 610 ' in the first incident angle range IA1 is about 66.5%, the average reflectance of the reflectance corresponding to the green wavelength 620 ' in the first incident angle range IA1 is about 61%, and the average reflectance of the reflectance corresponding to the red wavelength 630 ' in the first incident angle range IA1 is about 44.5%. On the other hand, the reflectivity of the second incidence angle range IA2 is much smaller than that of the first incidence angle range IA1, and may even be in the range of 0% to 5% in the present embodiment, regardless of the reflectivity of the corresponding blue, green and red wavelengths 610 ', 620 ', 630 '. Specifically, the average reflectance in the second incident angle range IA2 for the reflectance of the blue wavelength 610 ' is about 3%, the average reflectance in the second incident angle range IA2 for the reflectance of the green wavelength 620 ' is about 1.8%, and the average reflectance in the second incident angle range IA2 for the reflectance of the red wavelength 630 ' is about 1.6%. Therefore, the reflectance and the average reflectance in the first incident angle range IA1 are greater than those in the second incident angle range IA2 for any color.

In the present embodiment, similar to the trend of the variation of the reflectance of the embodiment of fig. 6A, in the first incident angle range IA1, the reflectance of the first reflectance distribution corresponding to the green wavelength 620 'is smaller than the reflectance thereof corresponding to the blue wavelength 610', and the reflectance of the first reflectance distribution corresponding to the red wavelength 630 'is smaller than the reflectance thereof corresponding to the green wavelength 620'. In addition, in fig. 6B, the reflectivities corresponding to the blue, green, and red wavelengths 610 ', 620 ', and 630 ' respectively tend to increase with increasing angle values in the first incident angle range IA 1. However, the first incident angle range, the second incident angle range, the range of the first reflectivity distribution and the range of the second reflectivity distribution are not limited in the present invention, and those skilled in the art can design and appropriately select them according to actual requirements.

In the embodiments of fig. 6A and 6B, the reflective coating on the reflective inclined plane is formed by stacking a plurality of thin films, for example, so that the reflectivity of the first incident angle range with a lower angle is greater than the reflectivity of the second incident angle range with a higher angle by using the principle of thin film interference. The films may be made of different materials, have different refractive indexes, or have different thicknesses, and those skilled in the art can design and appropriately select the films according to general knowledge, which will not be described herein. In addition, the formation of the reflective coating film is not limited in the present invention.

Next, referring to fig. 7, fig. 7 is a schematic view illustrating a reflection condition of a near-eye display device according to an embodiment of the invention on a reflection inclined plane. The near-eye display device illustrated in fig. 7 is, for example, the near-eye display device 100 in fig. 1, and the reflective coating film of the reflective inclined surface S13 may be any one of the embodiments in fig. 6A and 6B. And the right drawing AD is a distribution graph of the reflectance of the reflection inclined surface S13 with respect to different incident angles. Here, the first incident angle range IA1 'and the second incident angle range IA 2' are both continuous angle ranges, the first incident angle range IA1 'is equal to or greater than 17 degrees and equal to or less than 43 degrees, and the second incident angle range IA 2' is also equal to or greater than 70 degrees and equal to or less than 85 degrees.

The image light beam ML1 and the image light beam GL provided by the display (not shown) exit from the second light-emitting surface S22 of the second waveguide device 120, pass through the distance d between the second light-emitting surface S22 and the first light-incident surface S11, and enter the first waveguide device 110 from the first light-incident surface S11. After entering the first waveguide element 110, the image light beam ML1 is reflected once at the point B of the reflecting inclined surface S13, and then reflected to the first light splitting elements X1, X2, X3, X4, X5, and X6. The incident angle of the image beam ML1 at point B falls within the first incident angle range IA 1', and the encountered reflectivity is, for example, in the range of 40% to 90%, or 20% to 50%, or 20% to 70%. The other image beam GL is reflected for the first time at point a of the inclined reflection surface S13, and the incident angle is also within the first incident angle range IA 1', and the encountered reflectivity is, for example, within a range of 40% to 90%, or within a range of 20% to 50%, or within a range of 20% to 70%. However, the image light beam GL will be reflected for the second time at the point C of the inclined reflection surface S13, and the incident angle of this time falls within the second incident angle range IA 2', and the encountered reflectivity is less than 5%, and the reflected light beam cannot be effectively transmitted to the first light splitting elements X1, X2, X3, X4, X5, and X6, and enters the projection target, such as human eye. Therefore, the reflection inclined surface S13 of the present embodiment can suppress the undesired light generated by the secondary reflection to avoid the generation of the ghost image.

In addition, in an embodiment of the present invention, the surface of each light splitting element in each waveguide element has a transflective coating, i.e. a semi-transmissive and semi-reflective coating, so that the optical effect of partial transmission and partial reflection occurs. The embodiments of fig. 8 to 10 will explain the reflectance characteristics of the reflective coating film on the surface of the spectroscopic element of the present invention in detail.

Referring to fig. 8, fig. 8 is a schematic diagram illustrating a near-eye display device according to an embodiment of the invention. The near-eye display device 800 includes a first waveguide element 710 having a plurality of first light splitting elements X1, X2, X3, X4, X5, and X6 arranged in a first direction X, and a second waveguide element 720 having a plurality of second light splitting elements (not shown here) arranged in a second direction Y, respectively. The surfaces of the first light splitting elements X1, X2, X3, X4, X5 and X6 are provided with first transflective coating films, but the reflectivity characteristics of the first transflective coating films of the first light splitting elements can be the same or different. For example, the first light splitting elements X1, X2, X3, X4, X5 and X6 can be divided into three groups C1, C2 and C3 corresponding to three different reflectivity variations, and the reflectivity characteristics of the light splitting elements of the three groups C1, C2 and C3 can be referred to fig. 9A, 9B and 9C, respectively.

The present invention is not limited to the group classification method or the classification number of the first light splitting elements, and the reflectivity characteristics of each group may be the same or different, and those skilled in the art can make appropriate adjustments according to the actual situation.

Fig. 9A shows a reflectivity distribution diagram of the first light splitting element according to an embodiment of the invention. In this embodiment, FIG. 9A shows the reflectivity variation of group C1. In the third incident angle range IA3, the first transflective film belonging to the group C1 has a small difference in reflectivity from the incident light of different wavelengths. In the present embodiment, the third incident angle range IA3 and the fourth incident angle range IA4 are each continuous angle ranges, and the size of the third incident angle range IA3 falls within the range of 19 degrees to 41 degrees, for example. The angle of the third incident angle range IA3 is lower than that of the fourth incident angle range IA4, for example, the third incident angle range IA3 is 19 degrees or more and 41 degrees or less, and the fourth incident angle range IA4 is 75 degrees or more and 85 degrees or less.

FIG. 9A shows a reflectance curve 910A for blue light (e.g., corresponding to a wavelength of 449nm), reflectance curves 920A, 930A, and 940A for three different green lights (e.g., corresponding to wavelengths of 520nm, 530nm, and 550nm, respectively), and a reflectance curve 950A for red light (e.g., corresponding to a wavelength of 632 nm). The reflectance distribution in the third incident angle range IA3 is in the range of 7% to 16%, and has a tendency to rise as the angle value becomes larger in the third incident angle range IA 3.

The first transflective coating of group C1 is within a third incident angle range IA3, which has no large difference between the reflectivities corresponding to red wavelength 950A, blue wavelength 910A,

green wavelength

920A, 930A, 940A, the difference of the wavelengths falling within the range of 0 to 5%. And the reflectivity of the first transflective film of group C1 in the fourth incident angle range IA4 corresponding to red wavelength 950A, blue wavelength 910A,

green wavelength

920A, 930A, 940A is less than 5%. Further, the reflectance in the third incident angle range IA3 is larger than that in the fourth incident angle range IA4 on average. The measured values take into account the generation of errors.

Fig. 9B shows a reflectivity distribution diagram of the first light splitting element according to an embodiment of the invention. Shown in fig. 9B is the reflectivity variation of group C2, which has reflectivity variation characteristics similar to the embodiment of fig. 9A, except that the third incidence angle range IA3 is 19 degrees or more and 38 degrees or less, and the fourth incidence angle range IA4 is 75 degrees or more and 85 degrees or less.

FIG. 9B shows a reflectance curve 910B for blue light (e.g., corresponding to a wavelength of 449nm), reflectance curves 920B, 930B, and 940B for three different green lights (e.g., corresponding to wavelengths of 520nm, 530nm, and 550nm, respectively), and a reflectance curve 950B for red light (e.g., corresponding to a wavelength of 632 nm). The reflectance distribution in the third incident angle range IA3 is in the range of 17% to 25%, and has a tendency to rise as the angle value becomes larger in the third incident angle range IA 3.

The first transflective coating of group C2 is within a third incident angle range IA3, which has no large difference between the reflectivities corresponding to red wavelength 950B, blue wavelength 910B,

green wavelength

920B, 930B, 940B, the difference of the wavelengths falling within the range of 0 to 5%. And the reflectivity of the first transflective film of group C2 in the fourth incident angle range IA4 corresponding to red wavelength 950B, blue wavelength 910B,

green wavelength

920B, 930B, 940B is less than 5%.

Fig. 9C is a diagram illustrating a reflectivity distribution of the first light splitting element according to an embodiment of the invention. FIG. 9C shows the reflectivity variation of group C3, which has reflectivity variation characteristics similar to those of the embodiments of FIGS. 9A and 9B, except that the third incident angle range IA3 is 19 degrees or more and 28 degrees or less. The fourth incident angle range IA4 is 75 degrees or more and 85 degrees or less.

FIG. 9C shows a reflectance curve 910C for blue light (e.g., corresponding to a wavelength of 449nm), reflectance curves 920C, 930C, and 940C for three different green lights (e.g., corresponding to wavelengths of 520nm, 530nm, and 550nm, respectively), and a reflectance curve 950C for red light (e.g., corresponding to a wavelength of 632 nm). The reflectance distribution in the third incident angle range IA3 is in the range of 28 to 34%, and has a tendency to rise as the angle value becomes larger in the third incident angle range IA 3.

The first transflective coating of group C3 is within a third incident angle range IA3, which has a small difference between the reflectivities corresponding to red wavelength 950C, blue wavelength 910C,

green wavelength

920C, 930C, 940C, the difference of the wavelengths falling within the range of 0 to 5%. And the reflectivity of the first transflective film of the group C3 in the fourth incident angle range IA4 corresponding to the red wavelength 950C, the blue wavelength 910C, the

green wavelength

920C, 930C, 940C is less than 5%.

Referring to fig. 10, fig. 10 shows a reflectivity distribution diagram of the second light splitting element according to an embodiment of the invention. And the surface of each second light splitting element of the second waveguide element is provided with a second penetration and reflection coating film. A second transreflective coating having the reflectivity characteristics shown in fig. 10 may be used for any of the second light splitting elements in the second waveguide element. In this embodiment, all the second light splitting elements in the second waveguide element have the same reflectivity characteristics, and all the second light splitting elements have the reflectivity characteristics shown in fig. 10.

Fig. 10 shows the reflectance variation for each wavelength for four different angles of incidence. The curve 1010 is the change in reflectance at an incident angle of 30 degrees for each wavelength, the curve 1020 is the change in reflectance at an incident angle of 40 degrees for each wavelength, the curve 1030 is the change in reflectance at an incident angle of 50 degrees for each wavelength, and the curve 1040 is the change in reflectance at an incident angle of 60 degrees for each wavelength. In this embodiment, the reflectance of the second transflective film at the wavelength corresponding to the different colors is very close to each other in the fifth incident angle range. The fifth incidence angle range is 30 degrees or more and 60 degrees or less. In particular, the difference between the reflectances corresponding to red, blue, and green is in the range of 3%.

In some embodiments of the present invention, the first light splitting element has a first transflective coating, the second light splitting element has a second transflective coating, the first transflective coating is in a third incident angle range, and a difference between reflectances of the first light splitting element corresponding to red, blue and green wavelengths is in a range of 5%, wherein a size of the third incident angle range is in a range of 19 degrees to 41 degrees. The second transflective film has a difference between reflectances corresponding to red, blue, and green wavelengths within a fifth incident angle range of 30 degrees or more and 60 degrees or less, which falls within a range of 3%. Therefore, the light splitting element of the near-eye display device of the embodiment of the invention can properly control the change of the image light beams with different angles when the image light beams enter and penetrate the light splitting element, and the reflectivity is insensitive to the change of the wavelength, so that the image picture can be kept uniform, and excellent display quality is provided.

The transflective coating film of the embodiment of the invention is formed by stacking a plurality of films in a multilayer manner, and the reflectivity change of each wavelength to different incidence angles is adjusted by utilizing the principle of film interference. The films may be made of different materials, have different refractive indexes, or have different thicknesses, and those skilled in the art can design and appropriately select the films according to general knowledge, which will not be described herein. In addition, the formation of the trans-plating film is not limited in the present invention.

In summary, the exemplary embodiments of the present invention provide a near-eye display device, in which the first waveguide device has a plurality of light splitting elements and a reflective inclined plane, and the reflective inclined plane enables an image beam entering the first waveguide device to be reflected and transmitted to the plurality of light splitting elements, so as to be split by the light splitting elements to exit the first waveguide device and be transmitted to a projection target, such as a human eye. The reflection inclined surface has a first reflectance distribution in a first incident angle range and a second reflectance distribution in a second incident angle range, wherein an angle of the second incident angle range is higher than an angle of the first incident angle range, and a reflectance average value of the first reflectance distribution is larger than a reflectance average value of the second reflectance distribution, wherein the first incident angle range and the second incident angle range are each a continuous angle range. Therefore, the reflection inclined plane can inhibit secondary reflection stray light generated by the image light beam incident near the joint of the reflection inclined plane and the light incident plane, thereby improving ghost in an image picture and providing good display quality. In another embodiment of the present invention, a near-eye display device is provided, in which the first waveguide has a plurality of light splitting elements and a reflection inclined plane, and the reflection inclined plane reflects and transmits an image beam entering the first waveguide to the plurality of light splitting elements, so that the image beam is split by the light splitting elements and exits the first waveguide to be transmitted to human eyes. The surface of the light splitting element is provided with a transflective coating film, the transflective coating film is in a specific continuous incidence angle range, the difference between the reflectances corresponding to the red, blue and green wavelengths is in the range of 5%, and the size of the specific continuous incidence angle range is in the range of 19-41 degrees. Therefore, the beam splitting element can be determined according to different reflectivity requirements, the change of the image beams with different angles when the image beams enter and penetrate the beam splitting element is properly controlled, and the reflectivity is insensitive to the change of the wavelength, so that the image picture can be kept uniform, and excellent display quality is provided.

The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the scope of the invention, which is intended to cover all the modifications and equivalents of the claims and the specification, which are included in the invention. Furthermore, it is not necessary for any embodiment or claim of the invention to address all of the objects, advantages, or features disclosed herein. In addition, the abstract and the title of the invention are provided for assisting the retrieval of patent documents and are not intended to limit the scope of the invention. Furthermore, the terms "first", "second", and the like in the description or the claims are used only for naming elements (elements) or distinguishing different embodiments or ranges, and are not used for limiting the upper limit or the lower limit on the number of elements.

Description of the reference numerals

100. 800: near-to-eye display device

110. 510, 710, 810: first waveguide element

120. 520, 720, 820: second waveguide element

130: display device

140: lens module

410: waveguide element

610. 610', 910A, 910B, 910C: blue wavelength

620. 620', 920A, 920B, 920C, 930A, 930B, 930C, 940A, 940B, 940C: wavelength of green

630. 630', 950A, 950B, 950C: red wavelength

1010: reflectivity change of 30 degree incident angle for each wavelength

1020: reflectivity change of 40 degree incident angle for each wavelength

1030: reflectivity change of 50 degree incident angle corresponding to each wavelength

1040: reflection change of incidence angle 60 degree corresponding to each wavelength

A. B, C: position of

C1, C2, C3: group of groups

d: distance between each other

ML: image light beam

ML 1: image beam with primary reflection generated on the reflection inclined plane

GL: image beam generating secondary reflection on reflection inclined plane

PA: transfer path

P: projecting an object

OA: optical axis

MLB1, MLB 2: light ray

IA1, IA 1': first incident angle range

IA2, IA 2': second incident angle range

IA 3: third incident angle range

IA 4: fourth incident angle range

IA 5: fifth incident angle range

S11: first light incident surface

S12: the first light emitting surface

S21: second light incident surface

S22: the second light emitting surface

S13, S713: reflecting inclined plane

S41: light incident surface

S42: light emitting surface

S43: inclined surface

I1, I2: display light beam

G1: ghost beam

X1, X2, X3, X4, X5, X6: first light splitting element

Y1, Y2, Y3, Y4: multiple second light splitting elements

X: a first direction

Y: second direction

Z: third direction

α, β: included angle

Claims

1. A near-eye display device comprising a display and a first waveguide element,

the display is used for providing an image light beam;

the first waveguide element comprises a first light incident surface, a first light emitting surface, a reflection inclined surface and a plurality of first light splitting elements, wherein the image beam is incident on the first waveguide element through the first light incident surface, and the image beam is reflected by the reflection inclined surface in the first waveguide element and transmitted to the plurality of first light splitting elements, and the plurality of first light splitting elements split the image beam and leave the first waveguide element through the first light emitting surface,

the reflection inclined plane has a first reflectance distribution in a first incident angle range and a second reflectance distribution in a second incident angle range, wherein angles of the second incident angle range are higher than those of the first incident angle range, and a reflectance average value of the first reflectance distribution is larger than that of the second reflectance distribution, wherein the first incident angle range and the second incident angle range are continuous angle ranges, and the first reflectance distribution has a tendency of rising as an angle value in the first incident angle range becomes larger.

2. The near-eye display device of claim 1, wherein, in the first range of incidence angles, the reflectance of the first reflectance distribution for green wavelengths is less than its reflectance for blue wavelengths, and the reflectance of the first reflectance distribution for red wavelengths is less than its reflectance for green wavelengths.

3. The near-eye display device of claim 1, wherein the first reflectivity profile has a reflectivity in the first range of angles of incidence that is greater than a reflectivity of the second reflectivity profile in the second range of angles of incidence.

4. The near-eye display device of claim 1, wherein each of the first light splitting elements has a first transflective coating on a surface thereof, the first transflective coating having a difference between reflectances corresponding to red, blue, and green wavelengths within a third incident angle range falling within a range of 5%, wherein a size of the third incident angle range falls within a range of 19 degrees to 41 degrees.

5. The near-eye display device of claim 4, wherein the first transflective film has a reflectivity of less than 5% for each of red, blue, and green wavelengths in a fourth incident angle range, wherein an angle of the third incident angle range is lower than an angle of the fourth incident angle range, and the fourth incident angle range is equal to or greater than 75 degrees and equal to or less than 85 degrees, wherein the third incident angle range and the fourth incident angle range are each a continuous range of angles.

6. The near-eye display device of claim 1, wherein the range of the second reflectance distribution is in a range of 0% to 10%, and the range of the first reflectance distribution is in a range of 40% to 90%.

7. The near-eye display device of claim 1, wherein the range of the second reflectance distribution is in a range of 0% to 10%, and the range of the first reflectance distribution is in a range of 20% to 70%.

8. The near-eye display device of claim 1, wherein the first incident angle range is 17 degrees or more and 43 degrees or less, and the second incident angle range is 70 degrees or more and 85 degrees or less.

9. The near-eye display device of claim 1, further comprising:

a second waveguide element disposed between the display and the first waveguide element, the second waveguide element including a second light incident surface, a second light emitting surface, and a plurality of second light splitting elements,

the image light beam from the display enters the second waveguide element through the second light incident surface, is transmitted to the plurality of second light splitting elements, exits the second waveguide element through the second light emitting surface, and enters the first waveguide element through the first light incident surface.

10. The near-eye display device according to claim 9, wherein each of the second light splitting elements has a second transflective film on a surface thereof, the second transflective film having a difference between reflectances corresponding to red, blue, and green wavelengths within a fifth incident angle range falling within a range of 3%, wherein the fifth incident angle range is 30 degrees or more and 60 degrees or less.

11. A near-eye display device comprising a display and a first waveguide element,

the display is used for providing an image light beam;

the first waveguide element comprises a first light incident surface, a first light emergent surface, a reflection inclined surface and a plurality of first light splitting elements, wherein the image light beam is incident on the first waveguide element through the first light incident surface, and is reflected by the reflection inclined surface in the first waveguide element and transmitted to the plurality of first light splitting elements, the plurality of first light splitting elements split the image light beam and leave the first waveguide element through the first light emergent surface to be transmitted to a projection target,

wherein the reflective inclined plane has a first reflectance distribution in a first incident angle range and a second reflectance distribution in a second incident angle range,

wherein each of the first light splitting elements has a first transflective coating film on a surface thereof, the first transflective coating film having a difference between reflectances corresponding to red, blue, and green wavelengths falling within a range of 5% within a third incident angle range, a size of which falls within a range of 19 degrees to 48 degrees.

12. The near-eye display device of claim 11, wherein the first transflective film has a reflectivity of less than 5% for each of red, blue, and green wavelengths in a fourth range of angles of incidence, wherein the third range of angles of incidence is lower than the fourth range of angles of incidence, and the fourth range of angles of incidence is greater than or equal to 75 degrees and less than or equal to 85 degrees, wherein the third range of angles of incidence and the fourth range of angles of incidence are each a continuous range of angles.

13. The near-eye display device of claim 11, further comprising:

a second waveguide element disposed between the display and the first waveguide element and including a second light incident surface, a second light emitting surface and a plurality of second light splitting elements,

wherein the image light beam from the display enters the second waveguide element through the second light incident surface, is transmitted to the plurality of second light splitting elements, exits the second waveguide element through the second light emitting surface, and enters the first waveguide element through the first light incident surface,

and a second transflective film on the surface of each of the second light splitting elements, wherein the second transflective film has a difference between reflectances corresponding to red, blue and green wavelengths within a range of 3% within a fifth incident angle range, wherein the fifth incident angle range is 30 degrees or more and 60 degrees or less.

14. The near-eye display device of claim 11, wherein the second range of incident angles is higher in angle than the first range of incident angles, and the average of the reflectivities of the first reflectance distribution is greater than the average of the reflectivities of the second reflectance distribution, wherein the first range of incident angles and the second range of incident angles are each a continuous range of angles.

15. The near-eye display device of claim 14, wherein, in the first range of incidence angles, the reflectance of the first reflectance distribution for green wavelengths is less than its reflectance for blue wavelengths, and the reflectance of the first reflectance distribution for red wavelengths is less than its reflectance for green wavelengths.

16. The near-eye display device of claim 14, wherein the first reflectance distribution has a tendency to increase as angle values in the first incident angle range become larger in the first incident angle range.

17. The near-eye display device of claim 14, wherein the first reflectivity profile has a reflectivity in the first range of angles of incidence that is greater than a reflectivity of the second reflectivity profile in the second range of angles of incidence.

18. The near-eye display device of claim 14, wherein the range of the second reflectance distribution is in a range of 0% to 10%, and the range of the first reflectance distribution is in a range of 40% to 90%.

19. The near-eye display device of claim 14, wherein the range of the second reflectance distribution is in a range of 0% to 10%, and the range of the first reflectance distribution is in a range of 20% to 70%.

20. The near-eye display device of claim 11, wherein the first incident angle range is 17 degrees or more and 43 degrees or less, and the second incident angle range is 70 degrees or more and 85 degrees or less.

21. A near-eye display device comprising a display and a first waveguide element,

the display is used for providing an image light beam;

wherein the reflection slope has a first reflectance distribution in a first incident angle range and a second reflectance distribution in a second incident angle range, wherein angles of the second incident angle range are higher than angles of the first incident angle range, and a reflectance average of the first reflectance distribution is larger than a reflectance average of the second reflectance distribution, wherein the first incident angle range and the second incident angle range are each a continuous angle range,

each of the first light splitting elements has a first transflective coating film on a surface thereof, the first transflective coating film having a difference between reflectances corresponding to red, blue, and green wavelengths falling within a range of 5% in a third incident angle range, wherein a size of the third incident angle range falls within a range of 19 degrees to 41 degrees.

22. The near-eye display device of claim 21, wherein the first transflective film has a reflectivity of less than 5% for each of red, blue, and green wavelengths in a fourth range of angles of incidence, wherein the third range of angles of incidence is lower than the fourth range of angles of incidence, and the fourth range of angles of incidence is 75 degrees or greater and 85 degrees or less, wherein the third range of angles of incidence and the fourth range of angles of incidence are each a continuous range of angles.

23. A near-eye display device comprising a display, a first waveguide element, and a second waveguide element disposed between the display and the first waveguide element,

the display is used for providing an image light beam;

the second waveguide element comprises a second light incident surface, a second light emitting surface and a plurality of second light splitting elements, wherein the image light beam from the display enters the second waveguide element through the second light incident surface and is transmitted to the plurality of second light splitting elements, and exits the second waveguide element through the second light emitting surface and enters the first waveguide element through the first light incident surface,

each of the second light splitting elements has a second transflective film on a surface thereof, the second transflective film having a difference between reflectances corresponding to red, blue, and green wavelengths within a range of 3% within a fifth incident angle range, wherein the fifth incident angle range is 30 degrees or more and 60 degrees or less.