Image display device

Abstract

To provide an image display device capable of realizing both of enlargement of a visual field angle and enlargement of Eyebox.SOLUTION: A mart glass 100 includes: a transmission hologram 102a for transmitting each pixel of incident image light at multiple different angles and generating multiple pieces of image light; and a reflection hologram 102b for performing Bragg diffraction of image light at a predetermined angle from among the pieces of image light. More specifically, the reflection hologram 102b is configured such that multiple reflection holograms having different incident angles capable of reflecting image light are disposed side by side. The reflection hologram 102b may be disposed overlappingly.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an image display device for displaying an image.

Background Art

[0002] In order to achieve a wider viewing angle and a larger eyebox of smart glasses, a method has been proposed in which light of display video is replicated into a plurality of parallel lights by a transmission hologram and reflected in the direction of the eyes by a reflection hologram.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the diffraction angle of video light is limited by the transmission hologram, although the viewing angle can be expanded, there is a limit to the expansion of the eyebox.

[0005] Therefore, an object of the present invention is to provide an image display device capable of achieving both an expanded viewing angle and an expanded eyebox.

Means for Solving the Problems

[0006] The image display device of the present invention includes a diffractive optical element that transmits each pixel of incident video light at a plurality of different angles to generate a plurality of video lights, and a reflective optical element that Bragg diffracts the video light at a predetermined angle among the video lights.

Effects of the Invention

[0007] According to the present invention, it is possible to achieve both an expanded viewing angle and an expanded eyebox.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0009] Embodiments of the present disclosure will be described with reference to the accompanying drawings. If possible, the same parts will be denoted by the same reference numerals and redundant descriptions will be omitted.

[0010] FIG. 1 shows an external view of the smart glasses of the present disclosure. As shown in the figure, the smart glasses 100 of the present disclosure are an image display device capable of visually recognizing an image by propagating the video light output from the scan display 101 inside the lens 102 and reflecting it to the user's eye M. In the present disclosure, the scan display 101 is an irradiation device capable of outputting video light in a beam shape.

[0011] FIG. 2 is a schematic diagram showing the transmission and reflection processing of video in the smart glasses 100 of the present disclosure.

[0012] As shown in the figure, the scan display 101 is arranged facing the incident surface of the image light of the lens 102 of the smart glass 100. That is, the lens 102 is arranged so as to be substantially perpendicular to the beam direction at the center of the image output from the scan display 101. A transmissive hologram 102a is attached to the incident surface from the scan display in the lens 102, and the image is diffracted (replicated) and separated into a plurality of angles by the transmissive hologram 102a and is incident on the reflective hologram 102b.

[0013] In FIG. 2, the transmissive hologram 102a diffracts the image light for each pixel from the scan display 101 at a predetermined angle. Although not described in FIG. 2, several hundred image lights (beams) for forming an image are output, diffracted, and reflected.

[0014] Also, the reflective hologram 102b Bragg diffracts the image light incident from a predetermined angle. In the present disclosure, Bragg diffraction may be simply expressed as reflection.

[0015] In FIG. 2, a plurality of reflective holograms 102b are provided. The image light propagating in the lens 102 is reflected a plurality of times within the lens 102, and the reflective hologram 102b reflects the image light incident at a determined angle for each.

[0016] In FIG. 2, a plurality of reflective holograms 102b are arranged side by side, and the Eyebox can be enlarged. The image light incident from the transmissive hologram 102a is reflected by the reflective hologram 102b1, but not 100% of the image light is reflected. A part of the image (for example, about 20% etc.) is not diffracted by the reflective hologram b1 and propagates while being reflected as it is in the glass. The reflective hologram 102b2 reflects the remaining image light to the user.

[0017] In the present disclosure, a critical angle at which video light propagates within the lens 102 is defined, and the diffraction angle of the transmission hologram 102a and the reflection angle of the reflection hologram 102b are defined so as to fall within that critical angle.

[0018] In FIG. 3(a), the transmission hologram 102a shows that it transmits the video light incident from the scan display 101. In FIG. 3, for simplicity of explanation, only the video lights G1 to G3 are shown.

[0019] As shown in the figure, the video light G corresponding to one pixel is transmitted through the transmission hologram 102a toward the reflection hologram 102b at different angles for each pixel. For example, in FIG. 3(a), the video lights G1 to G3 transmitted for each pixel are diffracted and transmitted at different angles by the action of the transmission hologram 102a. Although three video lights G1 to G3 are shown in the figure, of course, there are other video lights.

[0020] In this way, the video light for each pixel is transmitted at different angles and propagates within the lens respectively. Although omitted in FIG. 3(a), the transmission hologram 102a may separate (duplicate) the video light corresponding to one pixel and diffract it at a plurality of angles. Even in that case, it is necessary to make the angles different for each pixel.

[0021] FIG. 3(b) is a diagram showing the separation of the video of a generally known transmission hologram. This transmission hologram transmits the video lights G1 to G3, but they are transmitted at the same angle. In the figure, the video lights corresponding to one pixel are separated from each other.

[0022] FIG. 4(a) shows the video lights G1 and G2 to be diffracted in the reflection hologram 102b. As shown in the figure, in the reflection hologram 102b, the video lights G1 and G2 with a predetermined incident angle are reflected toward the user's eye M.

[0023] On the one hand, Fig. 4(b) is a diagram showing propagation in the prior art. Here, the video light G1 propagating within the lens 102 may be reflected within the lens, and the separated video light Gx may be incident on the reflection hologram 102b again. This causes ghosting. In the present disclosure, a thick volume hologram is used for the reflection hologram 102b, and due to its angular selectivity, the incident video light G etc. is configured not to diffract when incident again.

[0024] Fig. 5 is a diagram showing reflection holograms 102b1 and 102b2 with different reflection angles arranged in the propagation direction of the lens, and showing the interval between their convergence points. The convergence points of the video light reflected by each of the reflection holograms 102b1 and 102b2 are different. The interval K between these convergence points is desired to be narrower than the pupil diameter of the eye, for example, preferably 2 mm or less.

[0025] Fig. 6(a) is a diagram showing the reflection states of a plurality of reflection holograms 102b. As shown in the figure, as described above, the reflection hologram 102b has a defined incident angle at which it can reflect video light. In Fig. 6(a), the reflection holograms 102b1 and 102b2 have the same defined incident angle at which they can reflect. As described above, for example, when reflected at different angles by the reflection hologram 102b1, the remaining video light is reflected by the reflection hologram 102b2.

[0026] In the present disclosure, reflection holograms 102b3 and 102b4 may be further provided. Fig. 6(b) is a diagram showing that figure. The reflection holograms 102b3 and 102b4 each have the same incident angle at which they can reflect video light, but are different from the reflection holograms 102b1 and 102b2.

[0027] In the present disclosure, when the transmissive hologram 102a is configured to be able to separate the image light of one pixel at different angles, the reflective holograms 102b1 and 102b2 reflect the image light diffracted at one angle, and the reflective holograms 102b3 and 102b4 reflect the image light explained at an angle different from the one angle.

[0028] As described above, the image light that could not be reflected by the reflective hologram 102b1 is reflected by the reflective hologram 102b2, and the image light that could not be reflected by the reflective hologram 102b3 is reflected by the reflective hologram b4.

[0029] In this way, by diffracting a plurality of image lights at different angles with the transmissive hologram 102a and preparing a plurality of corresponding reflective holograms 102b, the interval between the convergence points can be shortened.

[0030] That is, for example, by arranging the reflective holograms 102b3 and 102b4 between the reflective holograms 102b1 and 102b2, the interval between the convergence points can be shortened.

[0031] FIG. 6(c) is a diagram showing the arrangement when a plurality of reflective holograms (from the reflective hologram 102b1 to the reflective hologram 102b4) are multiplexed and exposed on a single hologram recording medium. As shown in the figure, between the reflective holograms having the same characteristics (reflection angle), the reflective holograms 102b having different characteristics are recorded in an alternating manner so as to overlap each other.

[0032] FIG. 7 is a diagram showing that the widths H of the reflection holograms 102b are different. That is, FIG. 7 shows that the widths H1 and H2 of the incident surfaces of the reflection holograms 102b1 and 102b2 are different. The image light diffracted from the transmission hologram 102a is diffracted at different angles for each pixel and is incident on the reflection hologram 102b. In the reflection hologram 102b, since image light with different angles is incident, the range for receiving the image light is different. The deeper the propagation direction in the lens, the wider the incident surface needs to be. Also, in FIG. 7, the position of the convergence point of the reflection hologram 102b is adjusted so that the viewing angles are the same. That is, for each of the plurality of reflection holograms 102b, the position (distance L) of the convergence point P of the reflection hologram 102b is adjusted so that the plurality of reflected image lights are parallel.

[0033] In this way, by adjusting the convergence point P while changing the width of the reflection hologram 102b, ghosting can be prevented.

[0034] In the present disclosure, in FIG. 2, the transmission hologram 102a is used, but the present disclosure is not limited to this. As shown in FIG. 8, a reflection hologram 102c may be arranged on the upper surface side (reflective surface) of the lens 102 so that it functions as a diffractive optical element in the same manner as the transmission hologram 102a. That is, the image may be diffracted (replicated) at a plurality of angles by the reflection hologram 102c and incident on the reflection hologram 102b.

[0035] Next, the operation and effect of the smart glasses 100 of the present disclosure will be described. In the smart glasses 100 of the present disclosure, a transmission hologram 102a that transmits each pixel of the incident image light at a plurality of different angles to generate a plurality of image lights, and a reflection hologram 102b that Bragg diffracts the image light at a predetermined angle among the image lights are provided. That is, this reflection hologram 102b is configured by arranging a plurality of reflection holograms with different incident angles capable of reflecting image light side by side. These reflection holograms 102b may be arranged in an overlapping manner. Note that instead of the transmission hologram 102a, a reflection hologram 102c may be used.

[0036] According to this disclosure, the image light with multiple angles changed by the transmission hologram 102a is diffracted and incident on the reflection hologram 102b, and is Bragg diffracted therein. Therefore, it is possible to achieve both a viewing angle and Eyebox magnification. In addition, ghosting due to the image light re-incident on the reflection hologram can be prevented.

[0037] In addition, in the smart glasses 100 of this disclosure, a plurality of reflection holograms 102b with different incident angles capable of reflecting image light are arranged side by side. For example, the reflection hologram 102b1 and the reflection hologram 102b3 have different characteristics (incident angles) of the reflected image light. When the transmission hologram 102a replicates and diffracts the image light of one pixel in multiple directions (changing the output angle), each of the reflection holograms 102b can receive and reflect it.

[0038] In addition, according to this disclosure, high-resolution image light can be obtained.

[0039] In addition, in this disclosure, a plurality of reflection holograms 102b1, 102b2, etc. are arranged overlapping each other. Thereby, the interval between the convergence points can be adjusted to be short.

[0040] In addition, according to this disclosure, in each of the plurality of reflection holograms 102b, a reflection surface corresponding to the angle diffracted by the transmission hologram 102a is formed. That is, a single reflection hologram 102b is multiply exposed a plurality of times, and the entire image light is exposed. In the transmission hologram 102a, the diffraction angle of the image light is changed for each pixel, and accordingly, the reflection hologram 102b also has a reflection surface (incident angle for reflection) corresponding to the diffraction angle of the image light for each pixel determined.

[0041] In addition, in this disclosure, each of the plurality of reflection holograms 102b is configured to have a size corresponding to the width of the incident image light.

[0042] Since the image light diffracted by the transmission hologram 102a spreads according to its angle, the reflection hologram 102b needs to have a size (width) sufficient to receive the image light.

[0043] Also, in the present disclosure, the interval between the convergence points from the plurality of reflection holograms 102b is adjusted to be smaller than the pupil diameter of the eye.

[0044] Further, the smart glasses 100 of the present disclosure include a scan display 101 which is an image light output unit for incident image light to the transmission hologram 102a. This scan display 101 is disposed at a position facing the transmission hologram 102a.

[0045] Thereby, the incident angle of the image light from the scan display 101 with respect to the transmission hologram 102a and the reflection hologram 102b can be widened, and high resolution can be realized.

[0046] The image display device of the present disclosure has the following configuration. [1] A diffractive optical element that diffracts each pixel of the incident image light at a plurality of different angles to generate a plurality of image lights, A reflective optical element that Bragg diffracts the image light incident at a predetermined angle among the image lights, An image display device comprising the same. [2] The reflective optical element is configured by arranging a plurality of reflection holograms having a defined incident angle capable of reflecting the image light side by side, The image display device according to [1]. [3] The reflective optical element is configured by arranging a plurality of reflection holograms having different incident angles capable of reflecting the image light side by side, The image display device according to [1] or [2]. [4] The plurality of reflection holograms are arranged in an overlapping manner, The image display device according to [2] or [3]. [5] In each of the plurality of reflection holograms, a reflecting surface corresponding to the angle diffracted by the diffractive optical element is formed. The image display device according to any one of [2] to [4]. [6] Each of the plurality of reflection holograms is configured to have a size corresponding to the width at which the video light is incident. The image display device according to any one of [2] to [5]. [7] The interval between the convergence points from the plurality of reflection holograms is adjusted to be smaller than the pupil diameter of the eye. The image display device according to any one of [2] to [6]. [8] The reflective optical element is configured by arranging a plurality of reflection holograms having the same incident angle capable of reflecting the video light side by side. The image display device according to any one of [1] to [7]. [9] The diffractive optical element is configured by arranging a plurality of reflection holograms having the same incident angle capable of reflecting the video light and a plurality of reflection holograms having different incident angles alternately. The image display device according to [7].

[10] The diffractive optical element is provided with a video light output unit for incident the video light. The video light output unit is disposed at a position facing the diffractive optical element. The image display device according to any one of [1] to [8].

[0047] Each aspect / embodiment described in the present disclosure may be used alone, in combination, or may be switched and used during execution. Further, the notification of predetermined information (for example, the notification of "being X") is not limited to being explicitly performed, and may be performed implicitly (for example, by not performing the notification of the predetermined information).

[0048] As described in detail above, it is obvious to those skilled in the art that the present disclosure is not limited to the embodiments described in the present disclosure. The present disclosure can be implemented as modifications and variations without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is for illustrative purposes only and does not have any limiting meaning for the present disclosure.

[0049] The terms "determining" and "determining" used in the present disclosure may include a variety of operations. "Determining" and "determining" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up (searching, inquiring) (e.g., searching in a table, database, or another data structure), and considering something as having "determined" or "determined" the ascertained thing. Also, "determining" and "determining" may include considering something as having "determined" or "determined" something received (e.g., receiving information), transmitted (e.g., transmitting information), input, output, accessed (e.g., accessing data in memory). Further, "determining" and "determining" may include considering something as having "determined" or "determined" something resolved, selected, chosen, established, compared, etc. That is, "determining" and "determining" may include considering something as having "determined" or "determined" some operation. Also, "determining (determining)" may be read as "assuming", "expecting", "considering", etc.

[0050] The terms "connected" and "coupled," or any variations thereof, mean any direct or indirect connection or coupling between two or more elements and can include the presence of one or more intermediate elements between two elements that are "connected" or "coupled" to each other. The coupling or connection between elements can be physical, logical, or a combination thereof. For example, "connected" may be read as "accessed." As used in this disclosure, two elements can be considered to be "connected" or "coupled" to each other using at least one of one or more wires, cables, and printed electrical connections, as well as, by way of some non-limiting and non-exhaustive examples, electromagnetic energy having wavelengths in the radio frequency region, microwave region, and optical (both visible and invisible) region.

[0051] As used in this disclosure, the recitation "based on" does not mean "based only on" unless otherwise specified. In other words, the recitation "based on" means both "based only on" and "based at least in part on."

[0052] Any reference to an element using designations such as "first," "second," etc. used in this disclosure does not generally limit the quantity or order of those elements. These designations can be used in this disclosure as a convenient way to distinguish between two or more elements. Thus, a reference to a first and a second element does not mean that only two elements can be employed, or that the first element must precede the second element in any way.

[0053] In this disclosure, when the terms "include," "including," and variations thereof are used, these terms are intended to be inclusive in the same manner as the term "comprising." Further, the term "or" used in this disclosure is not intended to be exclusive.

[0054] In the present disclosure, for example, when articles are added by translation, such as a, an, and the in English, the present disclosure may include that the nouns following these articles are in the plural form.

[0055] In the present disclosure, the term "A and B are different" may mean "A and B are different from each other". Note that the term may also mean "A and B are each different from C". Terms such as "separate", "coupled", etc. may also be interpreted in the same way as "different".

Description of Reference Numerals

[0056] 100... smart glasses, 101... scan display, 102... lens, 102a... transmissive hologram, 102b... reflective hologram.

Claims

1. A diffractive optical element that diffracts each pixel of incident video light at a plurality of different angles to generate a plurality of video lights, A reflective optical element that Bragg diffracts the video light incident at a predetermined angle among the video lights, An image display device comprising the above.

2. The reflective optical element is configured by arranging a plurality of reflection holograms having a defined incident angle capable of reflecting the video light side by side, The image display device according to Claim 1.

3. The reflective optical element is configured by arranging a plurality of reflection holograms having different incident angles capable of reflecting the video light side by side, The image display device according to Claim 1.

4. The plurality of reflection holograms are arranged so as to overlap each other, The image display device according to Claim 2.

5. In each of the plurality of reflection holograms, a reflection surface corresponding to the angle diffracted by the diffractive optical element is formed, The image display device according to Claim 2.

6. Each of the plurality of reflection holograms is configured to have a size corresponding to the width of incidence of the video light, The image display device according to Claim 2.

7. The interval between the convergence points from the plurality of reflection holograms is adjusted to be smaller than the pupil diameter of the eye, The image display device according to Claim 2.

8. The reflective optical element is configured by arranging a plurality of reflection holograms having the same incident angle capable of reflecting the video light side by side, The image display device according to Claim 1.

9. The reflective optical element is configured by arranging a plurality of reflection holograms having the same incident angle capable of reflecting the video light and a plurality of reflection holograms having different incident angles alternately side by side, The image display device according to Claim 7.

10. A video light output unit for incident video light to the diffractive optical element is provided, The video light output unit is arranged at a position facing the diffractive optical element, The image display device according to Claim 1.

Images