JP3313122B2 - Display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for forming an image displayed on a display device on a transparent screen by using an image forming optical system. It relates to a so-called head-up display type display device.

2. Description of the Related Art A head-up display capable of superimposing the display of various devices on a front view (background) has been conventionally used in aircraft, especially in fighters, and recently applied to automobiles and the like from the viewpoint of improving safety and the like. Is also thriving.

[0003] By the way, if such a head-up display type display device can be used in a window service of a bank or other service industry, a speech stand for speeches and lectures, or a commentary seat for a sports game, etc., it is possible to reduce fatigue and improve efficiency. It is useful and convenient from the viewpoint of, for example. That is, since the image (second information) on the display can be superimposed and displayed in the front view (first information), the counter, a lecturer, a commentator, etc. do not move their eyes one by one. Necessary second information (account information, lecture materials, personal data of athletes, etc.) can be viewed at the same time, while keeping one information (customer, audience, game site, etc.) in the field of view.

[0004] Although the present invention has been developed to meet such a demand, the present invention is not limited to the above-mentioned applications, and may be, for example, a personal computer, a word processor, or another OA.
The present invention can be applied to general display devices including displays such as devices.

[0005]

2. Description of the Related Art Conventionally, CRTs, liquid crystal displays, plasma displays, and the like have been used as display devices for personal computers and word processors. However, conventional display devices are all opaque objects in the shape of a plate or a box, and while using them, their eyes are gazing at the display surface, so that they cannot see anything else. Or, while looking at something, in order to refer to the information displayed on the display device, it is necessary to move the line of sight to the display device, and during that time, keep your eyes away from what you were looking at Must. Therefore, if there is a transparent display device in which the background can be seen through, both the background and the display can be seen without moving the line of sight.

As a method of superimposing a display on a background, there is a head-up display (HUD). This superimposes the image (virtual image) of the display in the field of view and displays the image at a distance, so that not only the movement of the line of sight but also the movement of the focal point of the eye is unnecessary (FIG. 29). In FIG. 29, the background image and the image from the display
The light is reflected by the image combiner 101 via 3 and superimposed.

As an image combiner, a reflection hologram is generally used. This is because the wavelength selectivity of the reflection hologram increases the light use efficiency for both display light and background light. Since the head-up display itself is a known technique, a detailed description is omitted.

[0008]

It goes without saying that the head-up display technology can be used for the transparent display device described above, but if it is applied as it is, the position of the virtual image (display) will be on the device surface (image combiner surface). Therefore, it cannot be used with the same feeling as a conventional display device (CRT, liquid crystal display, etc.), and there is a sense of incongruity, or when displaying at a clear viewing distance (about 30 cm), the There has been a problem that the combiner surface is too close to the eye.

This will be described in detail with reference to FIG. 29 described above.
The HUD includes a display 105, a transmission hologram 103, and a reflection hologram (image combiner) 101. The image displayed on the display 105 is composed of two holograms 103, 1
With 01, an image is formed as a virtual image _IV on the opposite side of the image combiner as viewed from the position of the eye. Thus, the background B and the display image (virtual image) _IV can be superimposed.

The direction of diffraction and reflection of light by a hologram depends on the wavelength of light (wavelength dispersion). When using light with a wide wavelength band instead of monochromatic light such as a laser,
The chromatic dispersion is compensated by two holograms. Originally, it is meaningful to use the hologram for the image combiner, but it is used as a pair (101, 103) to correct chromatic aberration. When an imaging system is composed of two holograms, it is difficult to obtain a system with a large screen and a short focal length (the distance between the virtual image and the image combiner is short) (the numerical aperture becomes large and chromatic aberration correction is difficult). .

Therefore, when a head-up display is used, the position of the device (display surface) cannot be aligned with the position of the display as in a conventional display device (light emitting type).
When viewing the display at a clear viewing distance (about 30 cm), the image combiner comes close to the face, and cannot be said to be a display device that can be used practically.

An object of the present invention is to realize a display device which is transparent and whose display surface substantially matches the device surface.

[0013]

In order to achieve the above object, according to the present invention, an image displayed on a small-sized display is displayed.
An image is formed on a hologram surface by an image forming system, and the hologram is formed so as to have a function of deflecting the spherical wave light diverging from the position of the image forming system toward the position of the eye of the user of the display device. A hologram in which holograms that deflect spherical wave light diverging from the pupil position of the imaging system in different directions near the eye position in order to expand the viewing field range in which the display can be viewed is superimposed on multiple layers or holograms recorded in multiple layers Can be used.

That is, according to the present invention, a display for projecting a predetermined image, an image forming optical system for forming a real image of the image on the display at a predetermined position, and an image forming position of the image forming optical system And a transparent hologram screen that is arranged at a distance from the hologram and diffracts the real image in a predetermined direction with directivity.

The hologram constituting the transparent hologram screen can be realized by either a reflection hologram or a transmission hologram.

The hologram transmits spherical wave light diverging and propagating from the position of the imaging optical system for one wavelength in the display light spectrum to an observer located in the same or opposite space as the imaging optical system with respect to the hologram surface. A plurality of holograms diffracted toward a plurality of points near the position of the eye are superposed in multiple layers, or are multiplexed and recorded in the same photosensitive medium.

The hologram transmits a spherical wave light diverging from the position of the imaging optical system with respect to one wavelength in the display light spectrum to the first hologram positioned in the space on the same side or the opposite side of the hologram surface as the imaging optical system. And a first hologram that converts into a spherical wave light that propagates while converging toward the point, and a spherical wave light that propagates while diverging from the position of the imaging optical system for a different wavelength in the display light spectrum. A second hologram that converts into a spherical wave light propagating while converging toward a second point located on the same side as the imaging optical system with respect to the hologram surface, or is superposed in a multilayer, or the same photosensitive medium This is a hologram recorded in multiple layers in the layer, and these first and second two points are selected at the positions of the left and right eyes of the observer.

A wavelength bandpass filter for selectively transmitting light within a selective reflection wavelength range of the reflection hologram or an optical path folding mirror having wavelength selectivity is inserted in an optical path between the reflection hologram and the display. It is also possible. A variable aperture stop may be added to the imaging optical system.

According to another embodiment, the transparent hologram screen is formed by a transparent curved substrate on which a hologram is formed. In this case, the imaging optical system forms a planar image of the display on the curved hologram screen. It has a curvature of field for imaging. Other features will be apparent from the following description of the embodiments. In the present invention, "one wavelength" means a wavelength band having a certain width.

[0020]

The transparency of the hologram allows the display to be superimposed on the background, and the image combiner surface acts as an image emitting surface like the display surface of a conventional display device. Can be realized.

The hologram is located at a space on the same side as or opposite to the imaging optical system with respect to the hologram surface. The observer sees the actual image of the image on the display surface of the image combiner (reflection type hologram or transmission type hologram) because it has the function of converting into spherical wave light that propagates while converging toward the eye position of the observer. I can do it.

By setting the hologram image forming position to a plurality of positions near the eye, even if the eye moves within a certain range, the eye can be reliably captured in the field of view. The imaging position is preferably selected for the left and right eyes of the observer.

A wavelength bandpass filter disposed in the optical path between the reflection hologram and the display, or an optical path folding mirror having wavelength selectivity selectively allows light within the selective reflection wavelength width of the reflection hologram. Since the light is transmitted, for example, the display light can be set to a desired color. Also,
By making the wavelength band of the light incident on the reflection hologram equal to or smaller than the wavelength selection width of the reflection hologram itself, the light transmitted through the reflection hologram is weakened, so that no leakage light can be seen from around the display device. You can do so.

By controlling the size of the variable aperture stop provided in the imaging optical system, the visible range of the display image can be easily controlled. In addition, the present invention can be applied to a curved hologram screen, in which case it is only necessary to provide an imaging optical system with a field curvature aberration for forming a planar image of a display on the curved hologram screen. .

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to one embodiment of the present invention, in a display device 5 shown in FIG.
Is imaged on a medium surface of a transparent reflection type hologram (image combiner) 4 by an imaging means (lens or the like) 3,
A transparent display device is formed by directing the reflected diffraction light 21 from the reflection hologram 4 toward the position 6 of the user's eye.

The reflection type hologram 4 converts spherical wave light diverging from the pupil (or substantially center position) position 22 of the imaging means 3 with respect to the center wavelength λ _c (FIG. 2) of the display light wavelength band to the position of the eye. 6 (a convergent ray is shown by a bold line 23 in FIG. 1). Since a method for producing a reflection hologram is known, the description is omitted.

Light emitted from one point P in the display surface 2 forms a real image Q on the medium surface of the reflection hologram 4 by the imaging means 3. Although Q behaves like a point light source, the light divergence solid angle Ω is substantially equal to the light convergence solid angle Ω ₀ when the point Q is formed by the imaging means 3. Therefore, when it is desired to widen the range of the eye position 6 where the display can be seen, the aperture of the imaging system is enlarged accordingly (described later).

Light emitted from all points on the display surface 2 overlaps at the eye position 6, so that the entire display can be seen.
Here, considering the case where the reflection hologram 4 is replaced with the half mirror 7, as shown in FIG. 28, the entire display (indicated by the arrow in FIG. 1) cannot be simultaneously viewed simply by specular reflection. That is, since the reflection direction at each point of the real image does not always coincide with the position 6 of the eye of the user of the display device, a display device having a wide field of view cannot be realized with a planar optical element (mirror or the like) having a regular reflection function.

FIG. 3 shows a variation of the relative positional relationship between the display surface 2, the image forming means 3, the reflection hologram 4, and the eye position 6 in the present invention. FIG. 2A shows a case where the display surface 2 and the reflection type hologram 4 are installed perpendicularly to a direction 24 connecting the display surface 2 and the center of the reflection type hologram 4. Reflection hologram 4
Oblique (angle θ _o ) to the normal of (image combiner)
).

In this configuration, the apparent size of the display in the vertical direction is cos θ _o times the real image, but 0.8 when θ _o = 37 degrees.
Since it is about twice, it can be used without any practical problems.

FIG. 3B shows that the reflection type hologram 4 is
Is theta _i inclined with respect to 24, a case where the reflection direction was theta _o. Although it is advantageous in that θ _o can be reduced as compared with the case of FIG. 3A, the direction of reflection and diffraction by the reflection hologram 4 and the direction of regular reflection on the surface may be overlapped.
It should be noted that when the spectrum of the display light is wider than the wavelength selection range of the reflection hologram 4, the display is partially changed in display color and brightness.

FIG. 3C shows a case where the user of the display device looks at the reflection type hologram 4 vertically. It is preferable that the display surface 2 is perpendicular to the line of sight. However, since the reflection hologram 4 is greatly inclined (angle θ _i ) with respect to the direction 24, a load is imposed on the imaging system. The three positional relationships described above are determined according to the shape condition, application, and the like of the display device.

FIG. 4 shows an example of the configuration of an imaging system according to the present invention. Figure (a) is the most common one,
The display surface 2 and the reflection type hologram 4 (image surface) are perpendicular to the optical axis 25 of the image forming means 3 and correspond to FIG. FIG.
(b) and (c) correspond to the configuration of FIGS. 3 (b) and (c).

FIG. 4 (b) shows a case where the display surface 2 and the reflection hologram 4 (image surface) are perpendicular to the optical axis 25 of the imaging means (lens system) 3, as in FIG. 4 (a). However, the configuration uses a portion having a large image height. In practice, a lens system with a wide field of view is required.

FIG. 4C shows a case where the reflection type hologram 4 (image plane) is inclined with respect to the optical axis 25 of the imaging means 3.
The display surface 2 also needs to be inclined. Accordingly, trapezoidal distortion occurs in the image. The above three configurations are selected according to the amount of distortion allowed for display, the cost of the display device, and the application.

FIG. 5 is an explanatory diagram of an embodiment in which the display can be viewed with both eyes or the position range of the eye in which the display can be viewed is extended. It is described in FIG. 1 that the point P on the display surface 2 forms an image on the point Q on the reflection hologram 4 and diverges toward the eye position 6 at the solid angle Ω. When viewing the display (when the distance between the eye and the image combiner is short, for example, 30 cm), the cone 26 formed by the divergent light
In order to allow both eyes to enter the inside of the camera, the aperture of the imaging means 3 must be made large, and an expensive imaging means is required in order to achieve compatibility with a wide field of view. In order to use a relatively simple and inexpensive lens system as the imaging means 3, it is necessary to allow display light to reach both eyes 6a and 6b even with a small aperture.

The reflection type hologram 4a for converging the spherical wave light diverging from the pupil position 22 of the imaging means 3 toward the position 6a of the right eye of the display device user, and the pupil position of the imaging means 3 This can be easily achieved by superimposing the reflection type hologram 4b, which converges the spherical wave light diverging from 22 toward the position 6b of the left eye of the display device user, or by using the hologram 4 'recorded in multiplex. The method of creating a multiplexed hologram is also well known. In the text, "multiplex" means a case where a plurality of holograms are formed in the same recording medium layer, and "multilayer" means a case where recording medium layers each forming a desired hologram are overlapped.

FIG. 6 shows another embodiment of the present invention. The image displayed on the display surface 2 of the display 1 is transmitted through the image forming means 3 (for example, a lens system), and is reflected by the regular reflection mirror 8.
An image is formed on the reflection type hologram 4 (image combiner) which is installed vertically, and is reflected and diffracted toward the display user's eye 6 in the normal direction of the reflection type hologram 4.

The reason why the optical path is folded by the regular reflection mirror 8 is as follows.
This is for disposing the display 1 and the imaging means 3 horizontally. The display surface 2 is inclined with respect to the optical axis 25 of the imaging means 3. The tilt causes a trapezoidal distortion in the real image on the image combiner, which can be offset by distorting the display in an inverted trapezoidal shape.

As the reflection hologram 4, an off-axis reflection hologram having a function of converging the spherical wave diverging from the virtual image 22 'at the pupil position 22 of the lens system 3 toward the eye position 6 is used. The method of producing the hologram 4 is as shown in FIG. That is, a coherent spherical wave diverging from the point 6 and a spherical wave converging at the point 22 'interfere with each other to form a hologram in the photosensitive material layer (recording medium) 51 formed on the substrate 50. The above is a preparation method when the hologram production wavelength is the same as the peak wavelength used for display. However, when the wavelength used for display is different from the hologram production wavelength, the two beams to be interfered are considered in consideration of the wavelength difference. It is necessary to design the wavefront, but since the method is publicly known, the description is omitted. Regarding the hologram processing, the conventional procedure for creating a volume hologram may be used as it is.

In FIG. 6, the light reflected and diffracted by the reflection hologram 4 behaves as if the hologram surface is a light-emitting surface. However, the point having strong directivity is largely different from that of the conventional light-emitting display. different. All the reflected light propagates toward the vicinity of the eye 6 of the user of the display device. Therefore, bright display is possible.

The specularly reflected light 27 on the surface of the reflection hologram 4
(Dotted line in FIG. 6) can be removed from the field of view by creating the hologram off-axis. Since the reflection hologram has wavelength selectivity, only the display 1 is used for actual display.
Is limited to the wavelength band selected by the hologram.

In general, since the emission spectrum of the display is wider than the wavelength selection range of the hologram, wavelengths other than the wavelength selection range are transmitted through the combiner (transmitted light 28). In a transparent display device, if the user does not want the display contents to be known to a third party on the opposite side of the combiner, the transmitted light 28 must be eliminated. As one means for achieving this, the mirror 8 for folding the optical path may be replaced with a mirror having the same wavelength selectivity as the combiner hologram, such as a regular reflection hologram, a multilayer mirror, etc., instead of a mere aluminum-deposited mirror. As a result, light in a wavelength band that is not reflected by the combiner is removed in advance.

Although FIG. 6 is a side view of the apparatus, only one eye is drawn. However, in order to guide display light to both the left and right eyes, as described above (FIG. 5), the hologram is formed into a multilayer or multiplex. Recording can be performed. Regarding the restriction on the eye position 6, the larger the aperture of the imaging means 3 is, the less the restriction is. Therefore, the imaging means 3
By providing the adjustable aperture stop 9 in the vicinity of the pupil position 22, the spatial restriction range of the eye position 6 can be slightly changed.

FIG. 8 shows an example of the appearance of a display device according to the present invention. The transparent plate 10 (image combiner) on which the reflection hologram 4 is formed is installed vertically to the unit 11 (FIG. 6) containing the display 1, the image forming means 3, and the mirror 8, but the display device is used. If not, the structure is such that it can be rotated 90 degrees by a rotating mechanism (for example, the image combiner may be rotatably supported by the pin 53) and stored in a position parallel to the unit surface. 56 is a projection window, and 57 is a power cord.

Although the embodiment shown in FIG. 8 is based on the configuration shown in FIG. 3C, it goes without saying that the configuration shown in FIGS. 3A and 3B can be adopted. .

FIG. 9 shows still another embodiment of the present invention. Image combiner 10 is not a flat plate but a curved surface
When it is preferably 10 ', the image forming means 3 is provided with a field curvature characteristic, that is, a field curvature aberration. Thereby, the real image of the display surface 2 can be made to substantially coincide with the surface of the reflection hologram 4 formed on the curved substrate 10 '.

FIG. 10 shows a case where a transmission hologram 4 'is used as the image combiner 10 instead of a reflection hologram. The real image on the display surface 2 is transformed into a transmission hologram 4 '.
1 is similar to that of FIG. 1 except that the real image is diffracted toward the display user's eye position 6 on the opposite side of the imaging system with respect to the image combiner. Since multiplex recording is also possible in the transmission hologram 4 ', images can be made incident on both the left and right eyes.

When it is desired to prevent the regular reflection light 27 on the surface of the image combiner, a transparent plate provided with an antireflection film may be bonded. Further, the light 28 not diffracted by the transmission hologram 4 'does not enter the eyes if the hologram has a large deflection angle β. Since the transmission hologram 4 'has weak wavelength selectivity, the color of display light changes depending on the position of the eye.

In FIG. 10, when the eye is moved from top to bottom, the display light changes in the order of blue → green → yellow → red (when the display displays white). As described above, the present invention can realize the configurations shown in FIGS. 1 to 9 in exactly the same manner even when a transmission hologram is used.

By the way, the reflection hologram selectively reflects light in a narrow wavelength band (20 to 30 nm). Therefore, when a single reflection hologram is used as an image combiner, one-color display is performed. Display of two or more colors is achieved by a structure in which reflection holograms that reflect light in different wavelength bands are recorded in multiple layers or multiple layers.

For example, in order to realize a transparent display device capable of displaying two colors of yellow and red with the configuration shown in FIG. 1, a multiple recording reflection type having a wavelength selective reflection characteristic as shown in FIG. A hologram may be used. However, the multiplex-recorded reflection holograms converge spherical wave light diverging from the pupil position 22 of the imaging means 3 toward the eye position 6 of the display device user for wavelengths of 585 nm and 660 nm, respectively. Create with the function to convert to. The same function can be realized by a structure in which the two reflection holograms are separately formed instead of being multiplex-recorded, and are bonded to face each other.

When three-color display is performed, the number of holograms to be multiplexed or multi-layered may be set to three.
A multiple recording reflection hologram having a wavelength selective reflection characteristic as shown in FIG. However, multiplexed recorded reflection holograms are 445 nm (blue), 530 nm (green), 68
For a wavelength of 0 nm (red), a spherical wave light diverging from the pupil position 22 of the imaging means 3 is converted into a spherical wave light converging toward the position 6 of the display user's eye.

Instead of multiplex recording all three reflection holograms, they may be separately prepared and bonded. For example, it is possible to integrate two holograms by multiplex recording and a hologram recorded singly by bonding the holograms with the medium surface aligned. However, when all three holograms are created separately and bonded together, at least one substrate is sandwiched between hologram layers, resulting in a large displacement (mm order) corresponding to the thickness of the substrate.
Is generated. It should be noted that this makes it impossible to form a real image of the display surface on the three-layer hologram surface at the same time, and the sharpness may be reduced.

In the display device described with reference to FIG. 5, the reflection type hologram 4 '(4a, 4b) has a narrow reflection wavelength band of generally about 20 to 30 nm as can be seen from FIGS. When combined with a normal display having a band of about 70 nm or more, the light use efficiency is reduced. In such a case, a display with a high luminance may be used, but a display with a high luminance and a narrow emission wavelength band using a special phosphor is expensive. Some of the following embodiments (FIGS. 13 to 19) use an existing display having a spectrum and luminance and increase the display brightness without using such a high-luminance special display. A display device is realized.

[0056] The display device is basically the one of the user of the display device with light in a wavelength band reflection hologram 13 corresponding to the reflection-type hologram 4 'shown in FIG. 5 is centered at the wavelength lambda ₁ reflected toward the eye position 6a, prepared as for reflecting light in a wavelength band centered at a different wavelength lambda ₂ to the position of the other eye 6b of the user of the display device and the wavelength lambda ₁ The user of the display device can view images in different wavelength bands with the left eye and the right eye.

By providing the reflection hologram 13 that reflects light of two or more different wavelength bands in a multiplexed manner or superposed in layers, the wavelength band reflected by the reflection hologram 13 is provided. Is expanded,
The utilization rate of the display light is improved, and a bright display becomes possible. This makes it easy to visually recognize the superimposed display image even in a situation where the background is bright. In addition, by making the two reflection wavelength bands largely different and performing display including parallax information in accordance with each wavelength band, stereoscopic display is also possible.

The present invention is directed to a display device for performing monochrome display.
In the embodiment shown in FIG. 13, 1 is a display, 3 is a lens, etc.
The imaging means 13 uses the image 14 displayed on the display 1
Provided at a position where a real image 15 is formed by the image forming means 3.
Reflection hologram with wavelength λ₁Peak
Reflection wavelength band (hereinafter simply referred to as λ₁Abbreviation)
Reflection hologram 13a and wavelength λ_TwoReflection with peak
Wavelength band (hereinafter simply λ _TwoAbbreviated)
Hologram 13b with the hologram surface facing each other
It is configured by wearing.

Then, as shown in FIG. 14, the wavelengths λ ₁ and λ ₂ are set so as to differ from each other in the emission spectrum (shown by the curve C) of the display device by approximately the half width of the reflection wavelength band of the reflection hologram. . For example, when the full width at half maximum is about 30 nm, λ ₁ = 515 nm and λ ₂ = 545 nm are set. Curves A and B show the spectra of the reflection holograms 13a and 13b, respectively. Then, as shown in FIG. 13, the first reflection type hologram 13a is formed so that the spherical wave light diverging from the pupil position 22 of the imaging means 3 is focused on the position of the left eye 6a. The reflection hologram 13b is formed so that spherical wave light diverging from the pupil position 22 of the imaging means 3 is focused on the position of the right eye 6b.

In this embodiment thus constructed, the image 14 displayed on the display 1 is formed as a real image 15 on the surface of the reflection hologram 13 by the imaging means 3. Of the display light reflected by the reflection hologram 13, λ ₁ is mainly reflected toward the position of the left eye 6a of the display device user, λ ₂ is mainly reflected toward the position of the right eye 6b,
Enables viewing of displayed images.

According to the above-described embodiment, light of one wavelength band is allocated to each of the left and right eyes, whereas light of one wavelength band is conventionally distributed to both the left and right eyes. , The brightness increases. Here, a difference occurs in the display color between the left and right eyes. For example, a wavelength difference of 30 nm can be identified as a color. For example, 515 nm (yellowish green) and 545 nm (yellowish greenish yellow) can be distinguished. However, in binocular vision, a slight difference in color between the left and right eyes poses substantially no problem in monochrome display. light having a wavelength near the middle of lambda ₁ and lambda _2, the reflection-type hologram 13a, is reflected by both 13b, because a real image is on the hologram surface, a double image is not generated.

In the first embodiment described above, for λ ₁ and λ
_{Although the} holograms were separately formed for the _two holograms and bonded, the first reflection hologram 13
It is needless to say that the same function can be achieved by multiplex-recording the second reflection type hologram 13b and the second reflection type hologram 13b. FIG. 15 is a diagram showing another embodiment of the present invention. 13, the same parts as those in FIG. 13 are denoted by the same reference numerals.

This embodiment is different from the previous embodiment in that the first and second reflection holograms 13a and 13b constituting the reflection hologram 13 are multiplexed recording holograms 13c and 13b, respectively.
d. That is, the multiple (double) recording / reflection type hologram 13c acting on the wavelength λ ₁ and the multiple (double) recording / reflection type hologram 13d acting on the wavelength λ ₂ are adhered so that the hologram surfaces face each other, and the reflection type is obtained. A hologram 13 was created. How to select λ ₁ and λ ₂ is the same as in the first embodiment described above.

In the case of this embodiment, since the mixed color of λ ₁ and λ ₂ is viewed with both the left and right eyes, no color difference occurs between the left and right eyes, and the brightness is different from that of the first embodiment. Also improves.
In this embodiment, the reflection type hologram 13 is composed of 13c and 13d.
Although it was composed of three reflection holograms, three or more
Direct the light of three or more wavelength bands to the left eye and the right eye of the user for each wavelength, or direct the light in a plurality of directions near the position of the eye so that images can be viewed in a mixed color of three or more wavelength bands. You can also.

FIG. 16 is a view showing still another embodiment. 13, the same parts as those in FIG. 13 are denoted by the same reference numerals. This embodiment differs from the first embodiment described with reference to FIG. 13 in that the first reflection hologram 13a and the second reflection hologram 13b constituting the reflection hologram 13 are changed as follows. . That is, the first and second reflection holograms 13e and 13 selectively reflect wavelengths λ ₁ and λ ₂ ′ that are significantly different from the reflection wavelength bandwidth of the reflection hologram 13.
f is adhered to two layers or multiplex-recorded in a single layer hologram medium to form a reflection hologram 13, and an image (λ ₁ ) reflected from the display 11 only by the first reflection hologram 13e
And an image (λ ₂ ′) reflected only by the second reflection type hologram 13f.

According to the present embodiment configured as described above, stereoscopic display using parallax can be performed. That is, when the images for the left eye and the right eye including the disparity information are displayed by λ ₁ and λ ₂ ′, respectively, only the λ ₁ can be seen by the left eye 6 a and only the λ ₂ ′ can be seen by the right eye 6 b, so that the disparity is reduced It can be generated and stereoscopically viewed. Figure
FIG. 17 shows an example of selection of λ ₁ and λ ₂ ′. If λ ₁ is a blue region and λ ₂ ′ is a red region as shown in the figure, it looks like a stereoscopic view wearing conventional red-blue glasses, but in this embodiment, no red-blue glasses are required, and The background can be seen through.

In each of the above embodiments, when a plurality of holograms are adhered in multiple layers, the smaller the interval between the holograms, the better. This is because if the interval between the holograms is large, a difference occurs in the position of the real image plane, which leads to the generation of a double image. The specific bonding method is as follows when the hologram has two layers.
As shown in FIG. 18A, two substrates 18 each having a hologram 17 formed thereon may be bonded with an optical adhesive 19 or the like as shown in FIG. 18B so that the hologram surfaces face each other. The thickness of the adhesive layer can usually be suppressed to several tens μm or less, and does not affect the occurrence of double images.

When the hologram has three or more layers, FIG.
The holograms at both ends are, for example, several mm thick as the substrate 18
A hologram 17 is formed on a glass plate of this type, and the hologram sandwiched between the holograms is formed by forming the hologram 17 on a thin and transparent sheet 20, and these are optically bonded as shown in FIG. 19 (b). What is necessary is just to adhere with the agent 19 etc. Thereby, the thickness of the entire hologram including the substrate can be kept small.

As described above, the viewing area can be extended by the method shown in FIG. 5, but if the display light reflected by the hologram 4 'is spatially separated, the head is viewed while viewing the display. Move to the left or right or back and forth (propagation direction of display light)
A situation arises where the display is only visible with one eye. In this case, by increasing the aperture of the imaging lens 3, the spatial separation of the display light flux toward the left and right eyes can be eliminated, and the degree of occurrence of a situation where the display can be seen only with one eye can be reduced.
However, in this case, the brightness of the display may change.

FIG. 27 (a) shows the range (viewing area) in which the display can be viewed. When the eye is positioned in the shaded portion S, the brightness of the display is almost twice that of the other portions. Increase. Therefore, when the head is moved left and right while viewing the display, the brightness of the display changes and the display flickers. A display in which the brightness of the display changes depending on the position of the eyes causes fatigue and is not easy to use. If a rectangular mask is provided in the imaging lens system and the viewing zones are connected as shown in FIG. 27 (b), the problem of the brightness unevenness can be solved, but the boundary L (discontinuous line) can be eliminated. Can not.

The embodiment described below (FIGS. 20 to 26) realizes expansion of the visual field without generating a discontinuous line. Holographic screen 61 for diffracting real images
A hologram element having a function of converting a diverging solid angle or a converging solid angle of an incident light wave is formed in a two-dimensional array, and the individual holograms satisfying the Bragg condition for light in a predetermined wavelength band. Light incident direction of the element,
The light emitting directions are formed so as to pass through two narrow sections each including the predetermined points A and B or each point.

According to this, when a point on the display image forms a real image by the imaging lens system, the solid angle of the focused beam determined by the focal length and the aperture of the lens system is increased by diffraction at the hologram element. be able to. As a result, the viewing zone can be extended without generating discontinuous boundaries.

FIGS. 20A and 20B show an example of the structure and function of the holographic screen of the present invention. FIG. 7A is an overall view of the holographic screen 61, showing a state in which hologram elements for converting a solid angle of a divergent wave or a convergent wave and reflecting the hologram are formed in a two-dimensional array. However, since it is a schematic diagram, grid lines are shown, but the hologram (screen 61) is actually transparent.

FIG. 20B is an enlarged view of one reflection type hologram element 63. This reflection hologram reflects divergent light having a solid angle Ω with respect to light in a predetermined wavelength band, and converts the solid angle into Ω ′. If Ω ′> Ω, the divergence angle of light increases. The optical axis l ₁ of the light incident on each hologram element 63 and the optical axis l ₂ of the outgoing light are respectively A as shown in FIG.
It is created so as to pass through the points B and B. For all the hologram elements 63, the incident optical axis and the output optical axis are point A and point B, respectively.
Create to pass through a point. Above, strictly speaking, A
Even if the vehicle does not pass through the point and the point B, there are many cases where there is substantially no problem even in the vicinity of the point A and the vicinity of the point B.

FIG. 20 (a) shows a case where a divergent wave is reflected. However, as shown in FIGS. 21 (a), (b) and (c), (a)
When the divergent wave converges after reflection, (b) When the convergent wave diverges after reflection, (c) When the convergent wave is reflected,
The configuration of FIG. 20 (a) holds. Although the hologram element 63 is shown as a rectangular area in FIG. 20 (a), the shape is not limited to a rectangle. Also, the boundaries between hologram elements need not always be clear.

FIGS. 22 (a) and 22 (b) show an optical system of a display device constituted by using the holographic screen 61 shown in FIG. 20 (a). (a) is an overall view, and (b) is an enlarged view of a holographic screen. However, each reflection hologram 63 has a small circular shape. In FIG. 22A, an image 14 displayed on the display 1 is formed on the holographic screen 61 by the imaging lens 3 to form a real image 15. Each point of the real image is the left and right eyes 6a, 6 of the person using the display device.
The light propagates while diverging toward the middle point of b.

Here, the points A and B shown in FIG. 20A are the center of the exit pupil of the imaging lens 3 and the left and right eyes 6a and 6b, respectively.
The holographic screen 61 is created so as to match the midpoints of. Focusing on the point P of the display image 14, the envelope surface of the light beam is as shown by the hatched portions in FIGS. 22 (a) and (b). The convergence solid angle Ω by the imaging lens 3 becomes Ω ′ (> Ω) after reflection by the holographic screen 61, and shows the viewing zone (shown by a dotted line 60 ′ in FIG. 22A) in FIG.
It is possible to extend to the area indicated by 60.

FIG. 23 shows an example of a method for producing the holographic screen 61 as shown in FIGS. 22 (a) and 22 (b). Transparent board
A dry plate 70 having a hologram recording medium 73 formed on one side of 71 is prepared, coherent light L ₁ and L ₂ are irradiated from both sides, and the dry plate is developed to form a reflection hologram. One of the coherent lights L ₁ irradiating the dry plate 70 is a divergent spherical wave and the other is a convergent spherical wave L ₂ , and these coherent lights L ₁ and L ₂ are distributed index type lens array plate 75 disposed near the dry plate. Irradiate through. It is preferable that a mask 77 for cutting unnecessary noise light be formed on the surface of the gradient index lens array plate 75. By controlling the relative positions of the two gradient index lens array plates 75, it is possible to form a reflection type hologram lens formed by irradiating divergent waves from both sides of the dry plate in a two-dimensional array. The size of the reflection hologram lens (hologram element) is designed to be, for example, about several hundred μm in order to correspond to the pixels for display.

FIG. 24 shows the holographic screen 61 in macro form. The position of the diverging point of the diverging wave is determined in consideration of the center of the exit pupil of the imaging lens 3 of the display device to be formed later. Further, the focal position of the converging wave L ₂ is determined in consideration of the position of the eye of a user of the display device.
The incident angles of the two light beams L ₁ and L ₂ with respect to the dry plate 70 are set in accordance with the projection direction on the holographic screen and the viewing direction of the display.

The wavelength of the coherent light is selected according to the sensitivity of the hologram recording medium, but does not always coincide with the display wavelength band. In such a case, the installation position of the gradient index lens array plate 75, the two coherent lights L ₁ ,
Determining the irradiation direction of L _2.

FIG. 25 shows an example of a gradient index lens array plate 75. A region 83 having a different refractive index is formed in a substantially spherical shape on the transparent substrate 81 by a proton exchange method or the like. Since this is a known technique, the description is omitted. When the incident direction of light to the gradient index lens changes, aberration occurs.
There is no problem as long as it is within the size of the pixel.

Although the above description has been made centering on the reflection type holographic screen 61, it goes without saying that the display device can be realized by a transmission type holographic screen. (FIG. 26) However, since it is difficult to form an array of minute transmission type hologram lenses using a gradient index lens array plate, it is necessary to use another method such as mask exposure or EB drawing.

The above description of the reflection type holographic screen presupposes a single selective reflection wavelength. However, a structure in which a plurality of holographic screens selectively reflecting light in different wavelength bands are laminated. Thereby, multi-color display becomes possible. Alternatively, the same multi-coloring can be achieved by a structure in which multiple recordings are performed in a single medium instead of a multilayer.

[0084]

As described above, the real image of the image of the display is formed on the hologram surface of the image combiner, and the hologram diffracts the real image toward the eyes of the user of the display device. In addition, a non-virtual image (real image) type display device similar to a conventional display device can be realized. By using the transparent display device according to the present invention, it is possible to see the display and the background at the same time.

Further, by performing multiplex recording or multi-layering of the hologram, it is possible to expand the range of the position of the eye where the display can be viewed and to perform multi-color display. Since the hologram element has wavelength dispersion, it is usually used in combination with a hologram for canceling chromatic aberration. In the configuration of the present invention, since the real image exists on the hologram surface, there is also an advantage that no aberration occurs even if the deflection direction differs due to the wavelength difference.

According to the embodiment shown in FIGS. 13 to 19, an image displayed on a display is formed on a reflection type hologram surface by using an image forming system, and the reflected light is used by a user of the display device. A structure in which a hologram that reflects light in two different wavelength bands is double-recorded or superimposed in layers in a display device in which a displayed image and a background can be viewed at the same time by focusing on an eye position. By creating the two reflection holograms so that light is focused at different positions of the left and right eyes of the user of the display device, the brightness of the display can be increased.

Also, by making the two reflection wavelength bands largely different and performing display including parallax information in accordance with each wavelength band, a three-dimensional display is also possible. In addition, the reflection type hologram that has different reflection wavelength bands and focuses the display light at a plurality of points near the position of the user's eye of the display device is multiplex-recorded or has a multi-layer structure to improve the brightness of the display. Can be done.

Further, according to the present invention, the viewing range of the display can be expanded, and the display can be stably viewed even if the position of the head of the user of the display device is slightly moved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of a display device of the present invention.

FIG. 2 is a diagram showing an emission spectrum shape of a display incorporated in the display device of the present invention.

FIG. 3 is a diagram showing three examples of the positional relationship of the imaging system of the present invention.

FIG. 4 is a diagram illustrating an example of a positional relationship of an imaging system according to the present invention.

FIG. 5 is a diagram for explaining means for enlarging the viewing area of the display device according to the present invention.

FIG. 6 is a diagram showing a structure of a display device according to the present invention.

FIG. 7 is a diagram showing a method for producing a reflection hologram used in the present invention.

FIG. 8 is a diagram showing an appearance of a display device according to the present invention.

FIG. 9 is a diagram showing a modification of the imaging system of the present invention.

FIG. 10 is a diagram showing a configuration using a transmission hologram in an embodiment of the present invention.

FIG. 11 is a characteristic diagram of a hologram used for performing two-color display in the example of the present invention.

FIG. 12 is a characteristic diagram of a hologram used when performing three-color display in the example of the present invention.

FIG. 13 is a diagram showing another embodiment of the present invention.

14 is a diagram illustrating a selection example of a reflection wavelength band of a reflection hologram in the embodiment of FIG. 13;

FIG. 15 is a diagram showing another embodiment of the present invention.

FIG. 16 is a diagram showing still another embodiment of the present invention.

17 is a diagram illustrating a selection example of a reflection wavelength band of a reflection hologram in the embodiment of FIG. 16;

FIG. 18 is a diagram illustrating a method of bonding two holograms according to the present invention.

FIG. 19 is a diagram illustrating a method of bonding three or more holograms according to the present invention.

FIG. 20 is a diagram showing still another embodiment of the present invention.

FIG. 21 is a diagram illustrating three examples of a reflection form of an incident light beam in the present invention.

22 is a diagram illustrating an example of a display device using the hologram screen illustrated in FIG. 20.

FIG. 23 is a diagram showing a method of producing the hologram screen shown in FIG. 20.

24 is a diagram illustrating an overall outline of a creation system in FIG. 20.

25 is a view showing a lens eye of the creation system shown in FIG. 24.

FIG. 26 is a diagram showing a transmission type hologram screen in the present invention.

FIG. 27 is a diagram illustrating a display area.

FIG. 28 is a diagram for describing a problem when a half mirror is used for an image combiner.

FIG. 29 is a diagram illustrating an example of a conventional head-up display.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Display device 2 ... Display surface 3 ... Imaging means 4 ... Hologram 5 ... Display device 6 ... Eye position 7 ... Half mirror 8 ... Mirror 9 ... Aperture stop 10 ... Image combiner (substrate) 11 ... Unit 21 ... To the eye Beam 22 converging toward the pupil position of the imaging means

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ Identification code FI G09F 9/00 359 G09F 9/00 359 (72) Inventor Go Tsuyoshi Matsumoto 1015 Kamidadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Fujitsu Limited ( 72) Inventor Junji Tomita 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Shin Eguchi 1015, Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited (56) References JP 2-109015 (JP, A) JP-A-2-72320 (JP, A) JP-A-2-113218 (JP, A)

Claims (7)

(57) [Claims] A display for projecting a predetermined image; an image forming optical system for forming a real image of the image on the display at a predetermined position; and a real image arranged at an image forming position of the image forming optical system. A hologram screen that diffracts the light with a directivity in a predetermined direction, wherein the hologram transmits spherical wave light propagating while diverging from the position of the imaging optical system for one wavelength in the display light spectrum, to the right of the observer. A first hologram that converts to spherical wave light that propagates while converging toward the first point corresponding to the eye, and also diverges from the position of the imaging optical system for one wavelength different from the above-mentioned-wavelength in the display light spectrum. A display device comprising a second hologram that converts spherical wave light propagating while converging to spherical wave light propagating while converging toward a second point corresponding to the left eye of an observer. 2. The transparent hologram screen comprises a reflection hologram, and a wavelength bandpass filter for selectively transmitting light within a selective reflection wavelength width of the reflection hologram in an optical path between the reflection hologram and a display. The display device according to claim 1, wherein the display device is interposed. 3. The transparent hologram screen is constituted by a reflection hologram, and has a wavelength selectivity for selectively reflecting light within a selective reflection wavelength width of the reflection hologram in an optical path between the reflection hologram and a display. The display device according to claim 1, wherein an optical path folding mirror is interposed. 4. The image forming optical system according to claim 1, wherein a variable aperture stop is attached to the imaging optical system, and a visible range of a display image is controlled by changing the aperture stop. Display device. 5. A holographic apparatus wherein a reflection type or transmission type hologram lens is formed in an array in the same medium layer, and the directions of the incident axis and the output axis of each hologram lens are gradually changed. screen. 6. A holographic screen, a display, and a projection lens system according to claim 5, wherein a real image of an image in which each of these elements is displayed on the display is projected on the holographic screen surface by the projection lens system. Or a display device formed in the vicinity of the display device. 7. The holographic screen according to claim 1, wherein the holographic lens has an incident axis and an exit axis which are set so as to pass through a principal point of the projection lens system and a position of an eye of a display device user, respectively. 7. The display device according to 6.