JP2021096284A - Image display device - Google Patents

Abstract

To provide an image display device that can increase the light amount of an image formed in a depth direction and also can increase the visibility.SOLUTION: An image display device (100) includes: a light source unit (CW) for emitting a laser beam; a first beam splitter (BS1) for reflecting a part of light emitted from the light source unit (CW) to a first direction and transmitting the other light to a second direction; a first image forming optical unit for forming the light that travelled in the first direction into an image in a space; and a second image forming optical unit for forming the light which travelled in the second direction into an image in a space.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image display device, and more particularly to an image display device that superimposes and forms an image of a plurality of images in the depth direction of space.

Conventionally, as a device for displaying various information in a vehicle, an instrument panel that lights and displays an icon has been used. Further, as the amount of information to be displayed increases, it is also proposed to embed an image display device in the instrument panel or to configure the entire instrument panel with the image display device.

However, since the instrument panel is located below the windshield of the vehicle, it is not preferable for the driver to visually recognize the information displayed on the instrument panel because it is necessary to move the line of sight downward during driving. Therefore, a head-up display (hereinafter referred to as HUD: Head Up Display) that projects an image on the windshield so that the driver can read the information when he / she visually recognizes the front of the vehicle has also been proposed (for example, Patent Document 1). See). In such a HUD, an optical device for projecting an image onto a wide range of the windshield is required, and it is desired to reduce the size and weight of the optical device.

On the other hand, as an image display device that projects light using a small optical device, a glasses-shaped head-mounted HUD is known (see, for example, Patent Document 2). In the head-mounted HUD, the light emitted from the light source is directly applied to the viewer's eyes, and the image is projected on the viewer's retina.

Japanese Unexamined Patent Publication No. 2018-118669 Special Table 2018-528446

However, in the conventional head-mounted HUD, a light emitting diode or an organic EL element is used as a light source for projecting an image, and a liquid crystal display device is also used for image display, so that an image (aerial image) formed in space is used. It was difficult to improve the amount of light. In particular, when aerial images are superimposed against a background of a real space, it becomes difficult to ensure the visibility of the images even in an environment illuminated by sunlight during the daytime.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an image display device capable of improving the visibility of an image formed in the depth direction by improving the amount of light. And.

In order to solve the above problems, the image display device of the present invention reflects a light source unit that irradiates laser light and a part of the light emitted by the light source unit in the first direction, and secondly reflects the remaining light. A first beam splitter that transmits in a direction, a first imaging optical unit that forms an image of light traveling in the first direction in space, and a second imaging optical unit that forms an image of light traveling in the second direction in space. It is characterized by including an imaging optical unit.

In such an image display device of the present invention, the laser beam emitted by the light source unit is split by the first beam splitter and imaged by the first imaging optical unit and the second imaging optical unit, so that the image is formed in the depth direction. It is possible to improve the visibility by improving the amount of light of the image to be imaged.

Further, in one aspect of the present invention, either the first imaging optical unit or the second imaging optical unit includes a head-mounted display.

Further, in one aspect of the present invention, the first imaging optical unit or the other of the second imaging optical unit reflects a part of the light from the first beam splitter and transmits the remaining light. It includes a two-beam splitter, a first retroreflective unit that retroreflects the light reflected by the second beam splitter, and a dichroic mirror that reflects the light reflected by the first retroreflective unit.

Further, in one aspect of the present invention, a second retroreflective unit that retroreflects the light transmitted through the second beam splitter is provided.

Further, in one aspect of the present invention, a first half mirror that branches the light emitted by the light source unit and a first half mirror that reflects the light transmitted through the first half mirror toward the first surface of the first beam splitter. It includes a mirror and a second mirror that reflects the light transmitted through the first half mirror toward the second surface of the first beam splitter.

INDUSTRIAL APPLICABILITY The present invention can provide an image display device capable of improving the visibility by improving the amount of light of an image to be imaged in the depth direction.

It is a schematic diagram which shows the structure of the image display device 100 which concerns on 1st Embodiment. It is a schematic diagram explaining the image formation and visual recognition of the 3rd image H using the 1st imaging optical part of the image display device 100. It is a schematic diagram explaining the image formation and visual recognition of the 1st image A1 and the 2nd image A2 using the 2nd imaging optical part of the image display apparatus 100. It is a photograph which shows the image formation of the aerial image using the image display device 100. It is a schematic diagram which shows the structure of the image display device 110 which concerns on 2nd Embodiment. It is a photograph which shows the image formation of the aerial image using the image display device 110.

(First Embodiment)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings shall be designated by the same reference numerals, and redundant description thereof will be omitted as appropriate. FIG. 1 is a schematic view showing a configuration of an image display device 100 according to the present embodiment. As shown in FIG. 1, the image display device 100 includes a light source unit CW, lenses L1, L2, half mirrors HM1, HM2, mirrors M1, M2, M3, an aperture AP, a prism Pr, and a beam splitter BS1. It includes BS2, retroreflective parts RR1 and RR2, a dichroic mirror DM, and a head mount display HMD.

In the image display device 100 shown in FIG. 1, the viewer visually recognizes the first image A1, the second image A2, and the third image H projected by the light emitted from the light source unit CW at different distances in the depth direction. .. In FIG. 1, the direction in which the first image A1, the second image A2, and the third image H are lined up is the depth direction, the vertical direction orthogonal to the depth direction is the vertical direction, and the direction orthogonal to the depth direction is horizontal. The direction.

The light source unit CW is a device that irradiates a laser beam having a predetermined wavelength, and for example, a semiconductor laser device including a semiconductor laser element and a control circuit can be used. The laser light emitted from the light source unit CW is not limited as long as it has a wavelength in the visible light range, but is preferably red, blue, or green. Further, the light emitted from the light source unit CW may be a single color or a mixture of a plurality of colors. Further, red, blue, and green light may be emitted in a time-division manner. Further, the light emitted by the light source unit CW may be continuous light or pulsed light. Further, the light source unit CW may include a collimator lens and other optical elements. The light emitted by the light source unit CW can be irradiated as light including a predetermined image by using a liquid crystal display element or a DMD (Digital Mirror Device).

The lenses L1 and L2 are optical elements arranged in the path of the laser light emitted from the light source unit CW to collect and magnify the laser light. In the example shown in FIG. 1, the lens L1 is arranged between the light source unit CW and the half mirror HM1, and the lens L2 is arranged between the mirror M3 and the prism Pr. Here, an example using two lenses L1 and L2 is shown, but as will be described later, in order to adjust the positions of the first image A1, the second image A2, and the third image H formed in the air. , Other lenses may be added in any of the optical paths as needed.

The half mirrors HM1 and HM2 are substantially flat optical elements that reflect a part of the light incident on one surface and transmit the remaining part, and have an angle of 45 degrees with respect to the vertical direction and the depth direction. It is arranged so as to be. The reflectance and transmittance of the half mirrors HM1 and HM2 are not limited, but for example, one that reflects 50% and transmits 50% can be used. The mirrors M1, M2, and M3 are substantially flat optical elements that reflect light incident on the reflecting surface, and are arranged at an angle of 45 degrees with respect to the vertical direction and the depth direction.

The aperture AP is an optical element for transmitting only the light that has reached the limited region and limiting the irradiation region of the light. In the example shown in FIG. 1, the aperture AP is arranged between the lens L2 and the prism Pr, and the diameter of the light transmitted through the lens L2 and collected is limited to be incident on the light incident surface of the prism Pr. .. The prism Pr is an optical element for introducing light into the light guide body of the head-mounted display HMD.

In the example shown in FIG. 1, the laser beam emitted from the light source unit CW enters the half mirror HM1 through the lens L1, part of the laser light is transmitted and travels in the direction of the mirror M1, and the rest is reflected and reflected in the mirror M2. Proceed in the direction. The light incident on the mirror M1 is reflected by the reflecting surface and incident on one surface of the beam splitter BS1. The light incident on the mirror M2 is reflected by the reflecting surface and incident on the other surface of the beam splitter BS1.

The beam splitter BS1 is a member that transmits a part of the incident light and reflects a part of the incident light, and a partial reflector having a film for adjusting the reflectance on the surface can be used. The beam splitter BS1 is arranged so as to have an angle of 45 degrees with respect to the vertical direction and the depth direction. Further, the mirrors M1 and M2 are arranged so as to be inclined by 45 degrees with respect to the optical axis of the light incident on one surface and the other surface. The beam splitter BS1 corresponds to the first beam splitter in the present invention.

The head-mounted display HMD is an image projection unit that forms an image of a third image H in space. The specific configuration of the head-mounted display HMD is not limited, and known configurations such as those using a light guide plate and a diffraction grating and those that scan a laser beam onto the retina can be used. In the example shown in FIG. 1, the head-mounted display HMD includes a flat plate-shaped light guide plate and a half mirror HM2 formed in the light guide plate, and the light incident from the prism Pr propagates inside the light guide plate. It is reflected in the viewer's viewpoint direction by the half mirror HM2. As will be described later, the light reflected by the half mirror HM2 of the head-mounted display HMD forms an image of the third image H in space. Therefore, the mirror M3, the lens L2, the aperture AP, the prism Pr, and the like. The head-mounted display HMD constitutes the first imaging optical unit in the present invention.

The beam splitter BS2 is a member that transmits a part of the incident light and reflects a part of the incident light, and a partial reflector having a film for adjusting the reflectance on the surface can be used. The beam splitter BS2 is arranged so as to be inclined at an angle of 45 degrees with respect to the vertical direction and the depth direction. Further, it is arranged so as to be inclined by 45 degrees with respect to the optical axis of the light incident from the beam splitter BS1. Further, the beam splitter BS2 and the beam splitter BS1 are inclined in opposite directions, and are arranged so as to intersect each other at an angle of 90 degrees. The beam splitter BS2 corresponds to the second beam splitter in the present invention.

Here, any balance can be selected between the light transmittance and the reflectance of the beam splitters BS1 and BS2. For example, the transmittance is 50% and the reflectance is 50%. Further, although an example in which the tilt angles of the beam splitters BS1 and BS2 are orthogonal to 45 degrees is shown, an appropriate angle can be used from the relationship between the traveling direction of the laser beam and the imaging position of the image.

The retroreflective portions RR1 and RR2 are optical members that reflect the incident light in the incident direction while maintaining the light-collecting property, and use a structure or a prism in which minute glass beads are spread on the surface side of the reflective film. A retroreflective part of the structure can be used. The retroreflective unit RR1 is arranged below the beam splitter BS2, and its main surface is in the horizontal direction. The retroreflective unit RR2 is arranged in the depth direction alongside the beam splitters BS1 and BS2, and the main surface is in the vertical direction.

The dichroic mirror DM is an optical member that reflects the wavelength of the laser beam emitted by the light source unit CW and transmits light of other wavelengths. The dichroic mirror DM is arranged above the retroreflective portion RR1 and the beam splitter BS2, and is arranged so as to be inclined at an angle of 45 degrees in the depth direction. As will be described later, since the first image A1 and the second image A2 are imaged in space by the light reflected by the dichroic mirror DM, the beam splitter BS2, the retroreflective parts RR1 and RR2, and the dichroic mirror DM Consists of the second imaging optical unit in the present invention.

Further, although omitted in FIG. 1, an imaging lens may be arranged between the beam splitter BS2 and the dichroic mirror DM as a part of the imaging optical system. The imaging lens is an optical member for forming an image of light transmitted through the beam splitter BS2 at a predetermined position in space, and a plurality of lens groups may be used. Further, the first image A1, the second image A2, and the third image H, which are imaged in space by the laser beam emitted by the light source unit CW, may be a still image or a moving image, and the projected images are the same. It may be different.

FIG. 2 is a schematic view illustrating the imaging and visual recognition of the third image H using the first imaging optical unit of the image display device 100. A part of the light incident on one surface of the beam splitter BS1 passes through the beam splitter BS1 and reaches the mirror M3. Further, a part of the light incident on the other surface of the beam splitter BS1 is reflected by the beam splitter BS1 and reaches the mirror M3. The light that reaches the mirror M3 is reflected by the reflecting surface and enters the prism Pr via the lens L2 and the aperture AP. The light incident on the prism Pr travels in the light guide plate of the prism Pr and the head-mounted display HMD, reaches the half mirror HM2, and is incident on the viewer's field of view reflected by the half mirror HM2.

Here, the light traveling from the half mirror HM2 in the viewer's field of view becomes an optical path that expands in the viewer direction as shown by the broken line in FIG. 2 by appropriately designing the shape of the half mirror HM2. .. Therefore, the viewer visually recognizes the third image H at the imaging position in space on the extension of the optical path. Further, since the head-mounted display HMD and the half mirror HM2 are made of a translucent material, the background in the extension line direction of the line of sight can also be visually recognized.

FIG. 3 is a schematic view illustrating imaging and visual recognition of the first image A1 and the second image A2 using the second imaging optical unit of the image display device 100. A part of the light incident on one surface of the beam splitter BS1 is reflected by the beam splitter BS1 and reaches the beam splitter BS2. Further, a part of the light incident on the other surface of the beam splitter BS1 passes through the beam splitter BS1 and reaches the beam splitter BS2.

A part of the light reaching the beam splitter BS2 is reflected and travels in the retroreflective portion RR1 direction, is rereflected by the retroreflective portion RR1, and reincidents on the beam splitter BS2. The light re-entering the beam splitter BS2 passes through the beam splitter BS2, is reflected by the dichroic mirror DM, and is imaged as the first image A1 and the second image A2. The light formed as the first image A1 and the second image A2 passes through the head-mounted display HMD and reaches the viewer's eyes. Therefore, the viewer visually recognizes the first image A1 and the second image A2 in the air in the depth direction.

The remaining part of the light that has reached the beam splitter BS2 is transmitted and travels in the retroreflective section RR2 direction, is rereflected by the retroreflective section RR2, and reincidents on the beam splitter BS2. The light re-entering the beam splitter BS2 is reflected by the beam splitter BS2, reflected by the dichroic mirror DM, and imaged as the first image A1 and the second image A2.

As shown in FIG. 3, by using the retroreflective unit RR1 and the retroreflective unit RR2, the light retroreflected by the retroreflective unit RR2 is also reflected by the beam splitter BS2 and reaches the dichroic mirror DM, and the first It is imaged as an image A1 and a second image A2. Therefore, since the light transmitted through the beam splitter BS2 and the reflected light are used for imaging the first image A1 and the second image A2, the decrease in the amount of light is suppressed.

At this time, the light retroreflected by the retroreflective unit RR1 and the light retroreflected by the retroreflective unit RR2 are images of the same content branched by the beam splitter BS2, and reach the dichroic mirror DM by superimposing them on each other. There is a need to. Therefore, when the optical characteristics of the retroreflective unit RR1 and the retroreflective unit RR2 are the same, it is preferable that the distances from the retroreflective unit RR1 and the retroreflective unit RR2 to the beam splitter BS2 are equal.

In FIG. 1, the path of the light reflected by the mirror M1 is indicated by a chain line, and the path of the light reflected by the mirror M2 is indicated by a broken line. If the magnification of one of the lights is changed by inserting a lens separately in the path of these lights, the imaging positions of the first image A1 and the second image A2 are different as shown in FIGS. 1 and 2. Can be made.

As described above, in the viewer, the light forming the first image A1, the second image A2, and the third image H is incident on the viewing range of the same viewer, and the first distance is different in the depth direction. , The first image A1, the second image A2, and the third image H can be visually recognized at the second distance and the third distance. At the same time, the viewer can see the background that reaches the eyes through the dichroic mirror DM and the head-mounted display HMD. Therefore, the viewer visually recognizes an aerial image in which the first image A1, the second image A2, and the third image H are superimposed on the background.

FIG. 4 is a photograph showing the imaging of an aerial image using the image display device 100. The photograph of FIG. 4 is taken from the viewpoint position of the viewer in FIG. 1 in the direction of the head-mounted display HMD and the dichroic mirror DM, and the viewing range of the viewer is shown as an image. The x-axis direction, the y-axis direction, and the z-axis direction in FIG. 4 indicate the horizontal direction, the vertical direction, and the depth direction in FIG.

In the example shown in FIG. 4, a circular image is irradiated from the light source unit CW, the first image A1 is imaged at the first distance in the depth direction from the viewer, and the second image A2 is imaged at the second distance. Then, a third image H was formed at a third distance. In the figure, the circle with a diameter of about 2 mm indicated by the triangular arrow A is an image of the second image A2, and the circle with a diameter of about 0.75 mm indicated by the triangular arrow B is an image of the first image A1. The circle with a diameter of 0.5 mm indicated by the arrow * is an image of the third image H. In the background in FIG. 4, each part of the measuring device used in the experiment is visible, and even if the first image A1, the second image A2, and the third image H, which are aerial images, are superimposed on the background. It was confirmed that both the background and the aerial image can be visually recognized.

As shown in FIG. 4, in the image display device 100 of the present embodiment, the laser beam emitted by one light source unit CW is branched by the first beam splitter BS1 to form a first imaging optical unit and a second imaging unit. Since the image is formed by the optical unit, it is possible to improve the visibility by improving the amount of light of the image to be imaged in the depth direction.

(Second Embodiment)
Next, the second embodiment of the present invention will be described with reference to FIGS. 5 and 6. The description of the contents overlapping with the first embodiment will be omitted. FIG. 5 is a schematic view showing the configuration of the image display device 110 according to the present embodiment. The image display device 110 of the present embodiment is different from the first embodiment in that the half mirror HM3 is arranged between the half mirror HM3 and the mirror M1 and the beam splitter BS3 is arranged between the mirror M2 and the beam splitter BS1. There is. As shown in FIG. 5, the image display device 110 includes a light source unit CW, lenses L1, L2, half mirrors HM1, HM2, HM3, mirrors M1, M2, M3, an aperture AP, a prism Pr, and a beam splitter. It includes BS1, BS2, BS3, retroreflective parts RR1, RR2, a dichroic mirror DM, and a head mount display HMD.

As shown in FIG. 5, the laser beam emitted from the light source unit CW is incident on the half mirror HM1 via the lens L1, part of the laser light is transmitted and travels in the direction of the half mirror HM3, and the rest is reflected and mirrored. Proceed in the M2 direction. Part of the light incident on the half mirror HM3 is transmitted and travels in the direction of the mirror M1, and the rest is reflected and incident on one surface of the beam splitter BS3. The light incident on the mirror M1 is reflected by the reflecting surface and incident on one surface of the beam splitter BS1.

The light incident on the mirror M2 is reflected by the reflecting surface, reaches the other surface of the beam splitter BS3, passes through the beam splitter BS3, and is incident on the other surface of the beam splitter BS1. Light incident on one surface of the beam splitter BS3 is also reflected by the beam splitter BS3 and incident on the other surface of the beam splitter BS1. The light incident on one surface and the other surface of the beam splitter BS1 is imaged as an aerial image by the first imaging optical unit and the second imaging optical unit as in the first embodiment.

In the image display device 110 of the present embodiment, the laser beam transmitted through the half mirror HM1 is further branched by the half mirror HM3 to reach the beam splitter BS2 via the beam splitter BS3, so that the laser beam is reflected by the dichroic mirror DM. A fourth image A4, which is different from the first image A1 and the second image A2, is imaged in space. Further, as in the first embodiment, an optical element such as a lens may be appropriately arranged between the half mirror HM3 and the beam splitter BS3 to adjust the imaging position of the fourth image A4.

As described above, in the viewer, the light for forming the first image A1, the second image A2, the third image H, and the fourth image A4 is incident on the viewing range of the same viewer and is at different positions in the depth direction. The first image A1, the second image A2, the third image H, and the fourth image A4 can be visually recognized at the first distance, the second distance, the third distance, and the fourth distance. At the same time, the viewer can see the background that reaches the eyes through the dichroic mirror DM and the head-mounted display HMD. Therefore, the viewer visually recognizes an aerial image in which the first image A1, the second image A2, the third image H, and the fourth image A4 are superimposed on the background.

FIG. 6 is a photograph showing the imaging of an aerial image using the image display device 110. The photograph of FIG. 6 is taken from the viewpoint position of the viewer in FIG. 5 in the direction of the head-mounted display HMD and the dichroic mirror DM, and the viewing range of the viewer is shown as an image.

In the example shown in FIG. 6, a circular image is irradiated from the light source unit CW, the first image A1 is imaged at the first distance in the depth direction from the viewer, and the second image A2 is imaged at the second distance. Then, the third image H was imaged at the third distance, and the fourth image A4 was imaged at the fourth distance. The circle with a diameter of about 1 mm indicated by the triangular arrow C in the figure is an image of the fourth image A4. In addition to the first image A1, the second image A2, and the third image H shown in FIG. 4, the fourth image A4 was imaged as an aerial image superimposed on the background, and it was confirmed that the images could be visually recognized.

In the examples shown in FIGS. 5 and 6, only one set of the half mirror HM3 and the beam splitter BS3 is added to the path of the laser beam to form the fourth image A4, but a larger number of half mirrors and the beam splitter are formed. May be arranged to increase the number of aerial images to be imaged. Further, the positions where the half mirror and the beam splitter are arranged are not limited to those shown in FIG. 5 as long as they are in the path of the laser beam.

As described above, also in the image display device 110 of the present embodiment, the laser light emitted by one light source unit CW is split by the first beam splitter BS1 and is divided into the first imaging optical unit and the second imaging optical unit. Since the image is formed, it is possible to improve the visibility by improving the amount of light of the image to be imaged in the depth direction.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

100, 110 ... Image display device L1, L2 ... Lens RR1, RR2 ... Retroreflective part HM1, HM2, HM3 ... Half mirror BS1, BS2, BS3 ... Beam splitter M1, M2, M3 ... Mirror A1 ... First image A2 ... First 2 image H ... 3rd image A4 ... 4th image

Claims (5)

The light source that irradiates the laser beam and
A first beam splitter that reflects a part of the light emitted by the light source unit in the first direction and transmits the remaining light in the second direction.
A first imaging optical unit that forms an image of light traveling in the first direction in space,
An image display device including a second imaging optical unit that forms an image of light traveling in the second direction in space. The image display device according to claim 1.
An image display device characterized in that one of the first imaging optical unit and the second imaging optical unit includes a head-mounted display. The image display device according to claim 2.
The first imaging optical unit or the other of the second imaging optical unit
A second beam splitter that reflects part of the light from the first beam splitter and transmits the rest of the light.
A first retroreflective unit that retroreflects the light reflected by the second beam splitter,
An image display device including a dichroic mirror that reflects light reflected by the first retroreflective unit. The image display device according to claim 3.
An image display device including a second retroreflective unit that retroreflects light transmitted through the second beam splitter. The image display device according to any one of claims 1 to 4.
A first half mirror that branches the light emitted by the light source unit, and
A first mirror that reflects light transmitted through the first half mirror toward the first surface of the first beam splitter, and
An image display device including a second mirror that reflects light transmitted through the first half mirror toward a second surface of the first beam splitter.

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