WO2010116831A1 - Video display device and head-mounted display - Google Patents

Abstract

Provided is a video display device which does not require an optical element for eliminating variations in color, and which increases the efficiency with which the light from the light source is used while also preventing decreases in video quality due to ghosting or flares. The video display device is configured so that the light source emits light in each of the blue, green and red (BGR) wavelength ranges from the same light emission surface, the light emitted from the light source includes the peak emission intensity wavelength and a wavelength range surrounding the peak emission intensity wavelength for each of the BGR wavelength ranges, and each of the BGR wavelength ranges includes the peak diffraction efficiency wavelength of a holographic optical element (HOE) in the screen center principal ray.

Description

Video display device and head mounted display

The present invention relates to a video display device capable of observing a virtual image of a video displayed on a display element by superimposing it with an external image, and a head mounted display (hereinafter also referred to as HMD) including the video display device. It is about.

As a conventional video display device, for example, there is a video display device disclosed in Patent Document 1. In this video display device, the light sources corresponding to each color of red (R), green (G), and blue (B) are shifted to disperse each color light with a diffusion plate, and RGB color unevenness is reduced. Only the light of the portion thus made is incident on the display element (for example, LCD). By guiding the emitted light (image light) from the display element to the observer's pupil through a hologram optical element (hereinafter also referred to as HOE), the observer observes the external image in a see-through manner while observing the virtual image of the display image. It is possible to do.

JP 2002-296536 A (see paragraph [0003], FIG. 7)

However, in the configuration in which the positions of the RGB light sources are shifted, it is necessary to dispose the diffusion plate as an optical element in the optical path in order to eliminate RGB color unevenness in the pupil. Even if a diffusion plate is provided, the outside light diffused by the diffusion plate is not sufficiently mixed, and it is difficult to eliminate color unevenness. Since the sufficiently mixed color region is only the center portion of the diffused light, the sufficiently mixed color center portion is used to eliminate color unevenness, and there is a problem that the light use efficiency is low.

On the other hand, FIG. 16 shows the light emission characteristics of a conventional light source that emits white light with one chip. For example, if the above-described light source that emits white light is used as the light source of the video display device, a diffusion plate for eliminating color unevenness can be eliminated. However, the following problems arise.

For example, when a color image is observed by an observer, the peak wavelength of the diffraction efficiency of HOE exists in each wavelength region of BGR, that is, in each wavelength region of 400 nm to 500 nm, 500 nm to 570 nm, and 570 nm to 700 nm. Assume. The HOE causes the observer to observe an image by making light of a diffraction efficiency peak wavelength satisfying the Bragg diffraction condition and light in a wavelength region before and after the light beam reaching the center of the pupil enter the pupil of the observer. The light passes through different optical paths and becomes ghost light reaching the observer's pupil or flare light reaching outside the observer's pupil. For this reason, as shown in FIG. 16, there is no wavelength in which the R emission (radiation) intensity peaks in the R wavelength region, and the emission characteristics are broad across the G and R wavelength regions. Not only is the light use efficiency from the light source bad, but there is a possibility that the image quality itself will be greatly degraded.

The present invention has been made in order to solve the above-described problems, and the object thereof is to eliminate the need for an optical element for eliminating color unevenness and to have high use efficiency of light from a light source. An object of the present invention is to provide a video display device capable of avoiding deterioration in quality and a head mounted display including the video display device.

An image display device of the present invention includes a light source, a display element that modulates incident light to display an image, an illumination optical system that guides light from the light source to the display element, and optical image light from the display element. An observation optical system that leads to a pupil, and the observation optical system includes a volume phase type reflection type hologram optical element that diffracts and reflects image light from the display element in an optical pupil direction, The light emitted from the light source emits one light in each of the first wavelength region of 400 nm to less than 500 nm, the second wavelength region of 500 nm to less than 570 nm, and the third wavelength region of 570 nm to less than 700 nm. An intensity peak wavelength and an emission wavelength region including the emission intensity peak wavelength, and all the light in the emission wavelength region is emitted from the same emission surface of the light source, When a light beam emitted from the center of the display element and incident on the center of the optical pupil via the hologram optical element is a screen center chief ray, all the emission wavelength regions are the hologram optics for the screen center chief ray. The diffraction efficiency peak wavelength of the element is included.

The image display device of the present invention, in the second wavelength region, when the diffraction efficiency peak wavelength is λmax, the emission intensity peak wavelength is λpeak, and the half-value wavelength width of the emission intensity peak wavelength is Δλ,
| Λmax−λpeak | / Δλ <0.4
It is desirable to satisfy.

In the video display device of the present invention, in all the first to third wavelength regions,
| Λmax−λpeak | / Δλ <0.4
It is desirable to satisfy.

In the video display device of the present invention, the emission intensity peak values of the first wavelength region, the second wavelength region, and the third wavelength region are E _B , E _G , and E _R , respectively. The emission intensity between the emission intensity peak wavelength and the emission intensity peak wavelength in the second wavelength region, and the emission intensity between the emission intensity peak wavelength in the second wavelength region and the emission intensity peak wavelength in the third wavelength region When the lowest emission intensity bottom values are E _BG and E _GR , respectively.
E _B / E _BG > 2
E _G / E _BG > 2
E _G / E _GR > 2
E _R / E _GR > 2
It is desirable to satisfy all of the above.

In the video display device of the present invention, it is desirable that the same light emitting surface of the light source and the optical pupil are in a substantially conjugate positional relationship.

The video display device of the present invention may include a plurality of the light sources.

The image display device of the present invention may further include a diffusion plate that diffuses light from the plurality of light sources.

In the video display device of the present invention, it is desirable that the diffuser diffuses incident light only in the arrangement direction of the plurality of light sources.

In the video display device of the present invention, it is desirable that the diffuser plate and the optical pupil have a substantially conjugate positional relationship.

In the image display device of the present invention, one of the exposure light sources for exposing the hologram photosensitive material used when the hologram optical element is manufactured may be disposed on a surface including the optical pupil of the observation optical system at the time of image observation. desirable.

In the image display device of the present invention, it is desirable that the diffraction efficiency of the hologram optical element in each wavelength region is set according to the emission intensity of each light source in each wavelength region.

In the video display device of the present invention, the diffraction efficiency of the hologram optical element in each wavelength region is highest in the wavelength region where the light emission intensity of the light source is the lowest and lowest in the wavelength region where the light emission intensity of the light source is highest. Is desirable.

In the image display device of the present invention, the diffraction efficiency in each wavelength region of the hologram optical element is such that the display element displays white when the display element displays white and the center of the display image is observed from the center of the optical pupil. Are XY chromaticity coordinates in the XYZ color system,
(X, Y) = (0.32 ± 0.05, 0.33 ± 0.05)
It is desirable that the color is set within the range of.

In the video display device of the present invention, the emission intensity peak wavelengths of the light sources in the first wavelength region, the second wavelength region, and the third wavelength region are λ _B , λ _G , and λ _R , respectively. When the half-value wavelength width of the emission intensity peak is ΔB, ΔG, ΔR, respectively,
0.05λ _B <ΔB <0.2λ _B
0.05λ _G <ΔG <0.2λ _G
0.05λ _R <ΔR <0.2λ _R
It is desirable to satisfy

The head-mounted display of the present invention includes the above-described video display device of the present invention and support means for supporting the video display device in front of the observer's eyes.

The first, second, and third wavelength regions correspond to the respective wavelength regions of BGR. Since all light in the emission wavelength regions of BGR included in the first to third wavelength regions is emitted from the same light emitting surface, uniform white light with no color unevenness can be obtained. Accordingly, for example, an optical element (for example, a diffusing plate) for eliminating the color unevenness without causing the color unevenness in the pupil that occurs when using the light source in which the light emitting portions emitting the respective colors of BGR are arranged is used. It becomes unnecessary to arrange.

(1) Since the light emitted from the light source has one emission intensity peak wavelength in each wavelength region of the BGR, the emission characteristics do not become broad across the adjacent wavelength regions in the BGR. Further, (2) each emission wavelength region including the emission intensity peak wavelength of BGR includes the diffraction efficiency peak wavelength of HOE with respect to the screen center chief ray. Close design is possible. By the above (1) and (2), the light use efficiency from the light source can be increased, and bright images can be observed, and the occurrence of ghosts and flares due to unnecessary light can be suppressed to avoid deterioration of the image quality. can do.

Therefore, according to the present invention, there is provided an image display device and a head-mounted display that eliminates the need for an optical element for eliminating color unevenness, increases the use efficiency of light from the light source, and avoids deterioration of image quality due to ghosts and flares. Can be provided.

It is sectional drawing which shows the schematic structure of the video display apparatus of one Embodiment of this invention. It is a top view of the light source of the said video display apparatus. It is sectional drawing which shows one structural example of the said light source. It is sectional drawing which shows the other structural example of the said light source. It is explanatory drawing which expands and shows the principal part of the manufacturing optical system of HOE of the said video display apparatus. It is explanatory drawing which shows the light emission characteristic of the said light source. It is explanatory drawing which shows the diffraction characteristic of the said HOE. It is explanatory drawing which shows the diffraction characteristic of HOE produced by arrange | positioning the reference light side light source in the center of an optical pupil for every arrival position of the up-down direction on an optical pupil surface. It is explanatory drawing which shows the XY chromaticity coordinate in an XYZ color system. It is a perspective view which shows the schematic structure of HMD provided with the said video display apparatus. It is sectional drawing which shows the schematic structure of the video display apparatus of other embodiment of this invention. It is a perspective view of the said video display apparatus. It is a top view of the light source unit of the said video display apparatus. It is a perspective view which shows the schematic structure of HMD provided with the said video display apparatus. It is sectional drawing which shows the other structure of a light source. It is explanatory drawing which shows the light emission characteristic of the conventional light source which light-emits white with 1 chip | tip.

<Embodiment 1>
An embodiment of the present invention will be described below with reference to the drawings.
[Video display device]
FIG. 1 is a cross-sectional view illustrating a schematic configuration of a video display device 1a according to the present embodiment. The video display device 1 a includes a light source 11, an illumination optical system 12, a display element 13, and an eyepiece optical system 14.

The light source 11 illuminates the display element 13, and in this embodiment, light in each wavelength region of blue (B), green (G), and red (R) is emitted from the same light emitting surface 11a shown in FIG. It is composed of a high color rendering white light source that emits light. Details of the light emission characteristics of the light source 11 will be described later. Such a light source 11 may be configured, for example, as illustrated in FIG. 3 or may be configured as illustrated in FIG.

The light source 11 in FIG. 3 includes an LED 22 that is a semiconductor light emitting element that emits B light, a green phosphor 23G that is excited by B light and emits G light, and is excited by B light. And a red phosphor 23R that emits R light. The LED 22 is mounted on a substrate 24 and connected to an electrode on the substrate 24 by a wire 25. In the housing 21, the LED 22, the green phosphor 23 </ b> G, and the red phosphor 23 </ b> R are sealed with a first sealing material 26 that is a molding material such as an epoxy resin, and further to the first sealing material 26. The side opposite to the substrate 24 is sealed with a second sealing material 27. As a result, the surface of the second sealing material 27 (the surface opposite to the substrate 24) is the same light emitting surface 11a.

The light source 11 of FIG. 4 replaces the LED 22 of the light source 11 of FIG. 3 with an LED 22 ′, newly provides a blue phosphor 23B, and replaces the green phosphor 23G and the red phosphor 23R with the green phosphor 23G ′ and the red phosphor 23R. It is replaced with '. The LED 22 ′ is a semiconductor light emitting element that emits near-ultraviolet light, and the blue phosphor 23B, the green phosphor 23G ′, and the red phosphor 23R ′ are excited by near-ultraviolet light, respectively, to emit B light, G light, R It is a phosphor that emits light.

The size of the light emitting surface 11a of the light source 11 is, for example, 1 mm in the vertical direction and 2 mm in the horizontal direction, and the magnification of the optical pupil P formed by the eyepiece optical system 14 with respect to the light source 11 is set to about 3 times. As a result, the size of the optical pupil P is, for example, 3 mm vertically and 6 mm horizontally. The light emitting surface 11a is disposed at a position substantially conjugate with the optical pupil P, and thereby, each light of BGR emitted from the same light emitting surface 11a can be efficiently guided to the optical pupil P. Therefore, when the observer's pupil is positioned at the position of the optical pupil P, the observer can observe a bright and high-quality image.

The illumination optical system 12 is an optical system that condenses light from the light source 11 and guides it to the display element 13, and includes, for example, an aperture stop 31 and a mirror 32 having a concave reflecting surface. The display element 13 modulates incident light according to image data and displays an image, and is composed of, for example, a transmissive LCD. The display element 13 is arranged so that the long side direction of the rectangular display screen is the horizontal direction (direction perpendicular to the paper surface of FIG. 1; the same as the left-right direction), and the short side direction is the direction perpendicular thereto.

The eyepiece optical system 14 is an observation optical system that guides the image light from the display element 13 to the optical pupil P (or the observer's pupil at the position of the optical pupil P). The eyepiece prism 41, the deflection prism 42, and the HOE 43 And is configured.

The eyepiece prism 41 totally reflects the image light from the display element 13 and guides it to the optical pupil P through the HOE 43, while transmitting the external light to the optical pupil P. Together with the deflecting prism 42, For example, it is made of an acrylic resin. The eyepiece prism 41 has a wedge-shaped shape at the lower end of the parallel plate. An upper end surface of the eyepiece prism 41 is a surface 41a as an incident surface for image light, and two surfaces positioned in the front-rear direction are surfaces 41b and 41c parallel to each other.

The deflection prism 42 is configured by a substantially U-shaped parallel plate in plan view (see FIG. 10), and when attached to the lower end portion and both side surface portions (left and right end surfaces) of the eyepiece prism 41, the eyepiece prism. 41 and a substantially parallel flat plate. The deflection prism 42 is provided adjacent to or adhered to the eyepiece prism 41 so as to sandwich the HOE 43. Thereby, the refraction when the external light passes through the wedge-shaped lower end of the eyepiece prism 41 can be canceled by the deflecting prism 42, and distortion of the external image observed through the see-through can be prevented.

The HOE 43 diffracts and reflects the image light (BGR light) from the display element 13 in the direction of the optical pupil P, while transmitting the external light and guiding it to the optical pupil P as a volume phase type reflection hologram. It is an optical element, and is provided on the joint surface of the eyepiece prism 41 with the deflection prism 42. The HOE 43 has an axially asymmetric positive optical power and has the same function as an aspherical concave mirror having a positive optical power. Thereby, the degree of freedom of arrangement of each optical member constituting the apparatus can be increased, and the apparatus can be easily reduced in size, and an image with good aberration correction can be provided to the observer. Details of the diffraction characteristics of the HOE 43 will be described later.

In the image display device 1a having the above configuration, the light emitted from the light source 11 passes through the aperture stop 31 of the illumination optical system 12, is reflected and condensed by the mirror 32, and is incident on the display element 13 as almost collimated light. Then, it is modulated and emitted as image light. The image light from the display element 13 enters the inside of the eyepiece prism 41 of the eyepiece optical system 14 from the surface 41a, and then is totally reflected by the surfaces 41b and 41c at least once and enters the HOE 43.

The HOE 43 has wavelength selectivity that functions as a diffraction element that diffracts light in each wavelength region of the BGR emitted from the light source 11 independently for each wavelength region. The HOE 43 is designed to function as a concave reflecting surface with respect to light in the emission wavelength region of the light source 11. Therefore, the light incident on the HOE 43 is diffracted and reflected there and reaches the optical pupil P. At the same time, external light passes through the HOE 43 and travels toward the optical pupil P. Therefore, by locating the observer's pupil at the position of the optical pupil P, the observer can observe the image displayed on the display element 11 as an enlarged virtual image, and at the same time, observe the outside world image with see-through. Can do. Note that various aberrations (coma aberration, curvature of field, astigmatism, distortion) are corrected in the eyepiece optical system 14 so that the viewer can observe the image displayed on the display element 13 satisfactorily.
[About manufacturing method of HOE]
Next, a method for manufacturing the above HOE 43 will be described. FIG. 5 is an explanatory view showing, in an enlarged manner, main parts of the manufacturing optical system of the HOE 43. As shown in FIG. The HOE 43, which is a reflection type color hologram, is manufactured by exposing the hologram photosensitive material 43a on the substrate (eyepiece prism 41) using two light beams for each BGR. At this time, one light beam is irradiated to the hologram photosensitive material 43a from the side opposite to the substrate, and this light beam is referred to as object light.

The other light beam is irradiated from the substrate side to the hologram photosensitive material 43a, and this light beam is referred to as reference light. If the exposure wavelengths (reference light and object light) of BGR are λ1 _B , λ1 _G , and λ1 _R , respectively, for example, λ1 _B = 476.5 nm, λ1 _G = 532 nm, and λ1 _R = 647 nm.

In the optical system on the object light generation side, RGB divergent light from the point light source 51 (object light side light source) is shaped into a predetermined wavefront by a free-form curved mirror 52 which is a reflection surface having optical power, and is reflected in a plane. After being reflected by the mirror 53, the hologram photosensitive material 43 a is irradiated through the color correction prism 54. Note that the surface 54a that is the incident surface of the object light in the color correction prism 54 is generated due to the refraction of the image light on the surface 41a of the eyepiece prism 41 of the eyepiece optical system 14 used during reproduction (image observation). The angle is determined so as to cancel the chromatic aberration. At this time, it is desirable that the color correction prism 54 is disposed in close contact with the hologram photosensitive material 43a in order to prevent a ghost due to surface reflection, or is disposed via emulsion oil or the like.

On the other hand, in the optical system on the reference light generation side, divergent light (for example, spherical waves) from the RGB point light sources 61R, 61G, and 61B, which are reference light side light sources, is used as reference light on the hologram photosensitive material 43a on the eyepiece prism 41 side. Irradiated from.

In this way, by exposing the hologram photosensitive material 43a with two light beams of object light and reference light for each of RGB, interference fringes are formed in the hologram photosensitive material 43a by interference of the two light beams, and the HOE 43 is manufactured. . At this time, the exposure with two light beams may be performed simultaneously for RGB or sequentially.

In the present embodiment, one of two exposure light sources (object light side light source, reference light side light source) that exposes the reference light side light source, that is, the hologram photosensitive material 43a used when manufacturing the HOE 43, is an eyepiece during image observation. The optical system 14 is disposed on a surface including the optical pupil P. Thereby, the image light from the display element 13 can be efficiently diffracted by the HOE 43 and guided to the optical pupil P during image observation. Therefore, by locating the observer's pupil at the position of the optical pupil P, the observer can observe a bright and high-quality image.

Here, the BGR exposure light source (reference light side light source) may all be at the same position on the surface of the optical pupil P, or the amount of deviation (exactly between the exposure wavelength and the used wavelength (emission intensity peak wavelength)). Alternatively, one of them may be shifted on the pupil surface in accordance with the amount of deviation of the ratio between the exposure wavelength and the used wavelength between different colors.

In the present embodiment, the point light sources 61R, 61G, and 61B are observed at the time of image observation so that the light having the emission intensity peak wavelength in each wavelength region of the BGR of the light source 11 is diffracted toward the center of the optical pupil P during image observation. On the surface of the optical pupil P. That is, as will be described later, with respect to B, since the deviation between the exposure wavelength and the emission intensity peak wavelength is large, only the point light source 61B is shifted from the other point light sources 61G and 61R on the surface of the optical pupil P. ing. On the other hand, for G and R, since the difference between the exposure wavelength and the emission intensity peak wavelength is small, the point light sources 61G and 61R are arranged at the center of the optical pupil P.

In this way, the point light sources 61R, 61G, and 61B are arranged in consideration of the amount of deviation between the exposure wavelength and the emission intensity peak wavelength, and the HOE 43 is manufactured, so that the center of the observer's pupil is located at the center of the optical pupil P during video observation. , The illumination light is reliably diffracted and reflected by the HOE 43 and reaches the observer's pupil at all angles of view. Therefore, the observer can observe a bright and high-definition image over the entire screen at the center position of the optical pupil P.
[Light emission characteristics of light source and diffraction characteristics of HOE]
Next, details of the light emission characteristics of the light source 11 and the diffraction characteristics of the HOE 43 will be described. FIG. 6 shows the light emission characteristics of the light source 11. The light emitted from the light source 11 emits one emission (radiation) in each of the first wavelength region of 400 nm or more and less than 500 nm, the second wavelength region of 500 nm or more and less than 570 nm, and the third wavelength region of 570 nm or more and less than 700 nm. ) It has an intensity peak wavelength and an emission wavelength region including the emission intensity peak wavelength. The first to third wavelength regions correspond to the respective wavelength regions of BGR. Moreover, as said light emission wavelength area | region, the area | region within each wavelength area | region of BGR and the half value wavelength width of a light emission intensity peak can be considered, for example. Accordingly, for each of the BGRs, there is a relationship of the lower limit wavelength of the wavelength region ≦ the lower limit wavelength of the emission wavelength region, the upper limit wavelength of the wavelength region ≧ the upper limit wavelength of the emission wavelength region. In the following, the terms wavelength region and emission wavelength region are used separately from each other. In the light source 11, light in at least the emission wavelength region of BGR is emitted from the same light emitting surface 11 a (see FIG. 2 and the like).

In the present embodiment, when the emission intensity peak wavelengths in each wavelength region of BGR are λ2 _B , λ2 _G , and λ2 _R , respectively, and the half-value wavelength widths of the emission intensity peaks are Δλ2 _B , Δλ2 _G , and Δλ2 _R , respectively, λ2 _B = 453 nm, λ2 _G = 531 nm, λ2 _R = 652 nm, Δλ2 _B = 26 nm, Δλ2 _G = 100 nm, and Δλ2 _R = 120 nm. Therefore, as each emission wavelength region of BGR, here, regions of 440 nm to 466 nm, 500 nm to 570 nm, and 592 nm to 700 nm can be considered.

On the other hand, FIG. 7 shows the wavelength characteristic of the diffraction efficiency of the HOE 43. Here, a light beam emitted from the center of the display element 13 and incident on the center of the optical pupil P through the HOE 43 is referred to as a screen center principal ray. In each wavelength region of BGR, suppose that the diffraction efficiency peak wavelengths of the HOE 43 for the screen center principal ray are λ3 _B , λ3 _G , and λ3 _R , respectively, and the half-value wavelength widths of the diffraction efficiency peaks are Δλ3 _B , Δλ3 _G , and Δλ3 _R , respectively. For example, λ3 _B = 453 nm, λ3 _G = 521 nm, λ3 _R = 634 nm, and Δλ3 _B = Δλ3 _G = Δλ3 _R = 10 nm.

In calculating λ3 _B , λ3 _G , and λ3 _R , the shrinkage rate of 2% of the hologram photosensitive material 43a is taken into consideration. For B, as described above, since the amount of deviation between the exposure wavelength λ1 _B and the emission intensity peak wavelength λ2 _B of the light source 11 is large, the position of the point light source 61B (see FIG. 5) at the time of exposure is shifted. Λ3 _B is corrected by exposure. Table 1 summarizes the characteristics of the light source 11 and the HOE 43.

In this embodiment, (1) the light emitted from the light source 11 has one emission intensity peak wavelength λ2 _B , λ2 _G , λ2 _R in each wavelength region of the BGR, so as shown in FIG. In addition, the emission characteristics do not become broad across wavelength regions adjacent to each other in BGR. Further, (2) each emission wavelength region of BGR (440 to 466 nm, 500 to 570 nm, 592 to 700 nm) includes the diffraction efficiency peak wavelengths (453 nm, 521 nm, and 634 nm) of HOE 43 with respect to the screen center principal ray, respectively. Therefore, as in the present embodiment, the BGR emission intensity peak wavelengths λ2 _B , λ2 _G , and λ2 _R of the light source 11 can be made closer to the diffraction efficiency peak wavelengths λ3 _B , λ3 _G , and λ3 _{R of} the HOE 43.

Therefore, according to the above (1) and (2), the light use efficiency of the light source 11 can be increased, and a bright image can be observed. In addition, light having wavelengths away from the diffraction efficiency peak wavelengths λ3 _B , λ3 _G , and λ3 _R can be prevented from being incident on the optical pupil P due to the low diffraction efficiency of the HOE 43, so that ghost and flare caused by unnecessary light can be prevented. It is possible to prevent the deterioration of the video quality by suppressing the occurrence.

In the light source 11, light in all emission wavelength regions of BGR is emitted from the same light emitting surface 11a, so that uniform white light without color unevenness can be obtained. Thus, for example, in a pupil that occurs when using a light source in which light emitting units emitting BGR colors are arranged (for example, a so-called 3 in 1 type LED in which chips emitting BGR light are arranged in one package) is used. Therefore, it is not necessary to dispose an optical element (for example, a diffusion plate) for eliminating the color unevenness. Therefore, in the case of the present embodiment, the configuration of the illumination optical system 12 can be simplified and the size of the apparatus can be avoided as compared with a configuration in which an optical element for eliminating color unevenness is provided.

By the way, the diffraction efficiency peak wavelength at the HOE 43 for the screen center chief ray is λmax (nm), the emission intensity peak wavelength of the light source 11 is λpeak (nm), and the half-value wavelength width of the emission intensity peak is Δλ (nm). When in the G wavelength region,
| Λmax−λpeak | / Δλ <0.4 (1)
It is desirable to satisfy.

By satisfying the conditional expression (1), the amount of deviation between the emission intensity peak wavelength λpeak of the light source 11 and the diffraction efficiency peak wavelength λmax of the HOE 43 becomes small in the G wavelength region where the relative visibility is high. The image light (G light) can be efficiently diffracted by the HOE 43 to allow the observer to observe a brighter and higher-quality image. In this embodiment, from Table 1, the value of | λmax−λpeak | / Δλ in the wavelength region of _G is 0.1 equivalent to | λ3 _G −λ2 _G | / Δλ2 _G, and conditional expression (1) is Satisfies.

Moreover, it is more desirable to satisfy the above conditional expression (1) in all the wavelength regions of BGR. In this case, since the amount of deviation between the emission intensity peak wavelength λpeak of the light source 11 and the diffraction efficiency peak wavelength λmax of the HOE 43 is small in all the wavelength regions of the BGR, the image light from the display element 13 is efficiently diffracted by the HOE 43. This makes it possible for the observer to observe a brighter color image with a wider color reproduction region. In this embodiment, from Table 1, the value of | λmax−λpeak | / Δλ is 0 equivalent to | λ3 _B −λ2 _B | / Δλ2 _{B in the B} wavelength region, and | λ3 _{R in the R} wavelength region. Since it is 0.15 equivalent to −λ2 _R | / Δλ2 _R , the conditional expression (1) is satisfied in all the wavelength regions of BGR.

Further, when the emission intensity peak wavelengths of the light source 11 in each wavelength region of BGR are λ _B , λ _G , and λ _R , respectively, and the half-value wavelength widths of the emission intensity peaks are ΔB, ΔG, and ΔR, respectively (unit is nm) )
0.05λ _B <ΔB <0.2λ _B (2a)
0.05λ _G <ΔG <0.2λ _G (2b)
0.05λ _R <ΔR <0.2λ _R (2c)
It is desirable to satisfy This is due to the following reason.

When the HOE 43 manufactured by arranging one of the two exposure light sources (reference light side light source) in the vicinity of the optical pupil P of the eyepiece optical system 14 at the time of image observation at the time of exposure is used, the position incident on the optical pupil P ( The wavelength at which the diffraction efficiency is maximized is shifted according to the distance from the pupil center.

For example, FIG. 8 shows the wavelength characteristics of the diffraction efficiency of the HOE 43 produced by setting the exposure wavelength to 532 nm and arranging the reference light side light source at the time of exposure at the center of the optical pupil P of the eyepiece optical system 14 on the optical pupil plane. Shown for each position reached in the vertical direction. Note that y = 0 corresponds to the point light source arrangement position (pupil center) at the time of exposure, and y = ± 1 and ± 2 correspond to positions shifted vertically from the position of y = 0. Yes. From the figure, it can be seen that the diffraction efficiency in the HOE 43 is maximized when the reproduction wavelength (use wavelength) is 532 nm, which is the same as the exposure wavelength, for the light beam reaching the position of y = 0. On the other hand, when reproduction is performed at a wavelength shifted from the exposure wavelength, the arrival position on the optical pupil plane of the light beam having the maximum diffraction efficiency is y = ± 1, ± 2,. To change. That is, in order to make the light beam having the maximum diffraction efficiency enter all positions in the plane of the optical pupil P, the half-value wavelength width of the emission intensity peak of the light source 11 is given a certain width (for example, 516 nm to 548 nm). It will be necessary.

In this embodiment, in each wavelength region of BGR, ΔB, ΔG, and ΔR are set to be equal to or higher than the lower limits of the conditional expressions (2a), (2b), and (2c), and by giving them a certain wavelength width, Light in each wavelength region of the BGR (especially, a light beam that maximizes the diffraction efficiency in the HOE 43) can reach any position in the plane. As a result, a bright image can be observed at any position within the plane of the optical pupil P. On the other hand, for each wavelength region of BGR, unnecessary flare reaching the outside of the optical pupil can be achieved by setting ΔB, ΔG, ΔR to be equal to or lower than the upper limit of conditional expressions (2a), (2b), and (2c) and limiting the half-value wavelength width to some extent. It is possible to realize a high-quality video display device 1a by reducing light. In this embodiment, from Table 1, λ _B , λ _G , and λ _R are 453 nm, 531 nm, and 652 nm equivalent to λ2 _B , λ2 _G , and λ2 _R , respectively, and ΔB, ΔG, and ΔR are Δλ2 _B , Δλ2 _G , respectively. 26 nm, 100 nm, and 120 nm equivalent to Δλ2 _R , the above conditional expressions (2a), (2b), and (2c) are all satisfied.

Each _E B the emission intensity peak value of the light source 11 in each wavelength region of _BGR, and E G, and _{E R,} between the emission intensity peak wavelength lambda _G of the emission intensity peak wavelength lambda _B and G of B, the emission intensity of the G When the emission intensity bottom values at which the emission intensity between the peak wavelength λ _G and the emission intensity peak wavelength λ _R is the lowest are E _BG and E _GR , respectively.
E _B / E _BG > 2 (3a)
E _G / E _BG > 2 (3b)
E _G / E _GR > 2 (3c)
E _R / E _GR > 2 (3d)
It is desirable to satisfy all of the above. This is due to the following reason.

By satisfying the above conditional expressions (3a) to (3d), the intensity of unnecessary light is lowered, the intensity of ghost light and flare light can be reduced, and the image quality can be improved. Taking the light emission characteristics of the light source 11 shown in FIG. 6 as an example, when the values corresponding to the conditional expressions (3a) to (3d) are obtained,
E _B / E _BG = 5.4
E _G / E _BG = 2.1
E _G / E _GR = 2.2
E _R / E _GR = 2.3
Thus, all the conditional expressions (3a) to (3d) are satisfied.
[Optimization of diffraction efficiency of HOE]
Next, optimization of the diffraction efficiency of the HOE 43 will be described.

In this embodiment, the diffraction efficiency in each wavelength region of the BGR of the HOE 43 is set according to the emission intensity in each wavelength region of the BGR of the light source 11. More specifically, the diffraction efficiency of the HOE 43 is set to be highest in the G wavelength region where the light emission intensity of the light source 11 is the lowest and lowest in the B wavelength region where the light emission intensity of the light source 11 is highest (FIG. 6). FIG. 7). As a result, the product of the diffraction efficiency of the HOE 43 and the emission intensity of the light source 11 is substantially constant in BGR.

When the light source 11 is formed of a fluorescent type LED as shown in FIGS. 3 and 4, for example, the emission intensity (BGR emission intensity ratio) of each wavelength region of the light source 11 is fixed. Accordingly, as described above, the HOE 43 is set according to the emission intensity in each wavelength region, such as setting the diffraction efficiency highest in the wavelength region where the emission intensity is lowest and setting the diffraction efficiency lowest in the wavelength region where the emission intensity is highest. By optimally setting the diffraction efficiency (BGR diffraction efficiency ratio) in each wavelength region of the light source, it is obtained through the HOE 43 while increasing the light use efficiency from the light source 11 (using the maximum amount of light). By adjusting the light to a desired color tone, an image with good color balance can be observed.

Further, the diffraction efficiency in each BGR wavelength region of the HOE 43 may be set as follows according to the emission intensity in each BGR wavelength region of the light source 11. That is, the diffraction efficiency of the HOE 43 is such that when the display element 13 displays white and the screen center of the display image is observed from the center of the optical pupil P, the color of the screen center is the XY chromaticity coordinate in the XYZ color system. ,
(X, Y) = (0.32 ± 0.05, 0.33 ± 0.05)
It may be set so that the color is within the range. FIG. 9 shows XY chromaticity coordinates in the XYZ color system, and W in the figure corresponds to the above range.

Screen that is observed when white is displayed on the display element 13 (the transmittance of each color in each pixel of the display element 13 is maximized) and the screen center of the display image (virtual image) is observed from the center of the optical pupil P If the diffraction efficiency of the HOE 43 is set according to the light emission intensity of the light source 11 so that the center color is white within the above range in the XY chromaticity coordinates, the light use efficiency is maximized for general images. In addition, it is possible to make the observer feel substantially white when observing an image displayed in white.

In addition, by adjusting the color of the image data according to the emission intensity in each wavelength region of the BGR of the light source 11 and the diffraction efficiency in each wavelength region of the BGR of the HOE 43, white in the above range is realized. Also good.
[About HMD]
The video display device 1a of the present embodiment can be applied to an HMD. Hereinafter, the HMD will be described.

FIG. 10 is a perspective view showing a schematic configuration of the HMD. The HMD includes a video display device 1 and support means 2. The video display device 1 corresponds to the video display device 1a described above.

The video display device 1 has a housing 3 that contains at least a light source 11 and a display element 13 (both see FIG. 1). The housing 3 holds a part of the eyepiece optical system 14. The eyepiece optical system 14 is formed by bonding an eyepiece prism 41 and a deflecting prism 42, and has a shape like one lens of a pair of glasses (lens for right eye in FIG. 10) as a whole. In addition, the video display device 1 has a circuit board (not shown) for supplying at least driving power and a video signal to the light source 11 and the display element 13 via a cable 4 provided through the housing 3. is doing.

The support unit 2 corresponds to a frame of glasses (including a bridge and a temple), and supports the video display device 1 in front of the observer's eyes (for example, in front of the right eye). Further, the support means 2 includes a nose pad 5 (right nose pad 5R / left nose pad 5L) that contacts the observer's nose, and a nose pad lock unit 6 that fixes the nose pad 5 at a predetermined position. Yes. The nose pad lock unit 6 holds the nose pad 5 with a spring shaft.

When the observer wears the HMD on the head and displays an image on the display element 13, the image light is guided to the optical pupil via the eyepiece optical system 14. Therefore, by aligning the observer's pupil with the position of the optical pupil, the observer can observe an enlarged virtual image of the display image of the image display device 1. At the same time, the observer can observe the outside world image through the eyepiece optical system 14 in a see-through manner.

Thus, by supporting the video display device 1 by the support means 2, the observer can observe the video provided from the video display device 1 in a hands-free and stable manner for a long time. In addition, you may enable it to observe an image | video with both eyes using two image display apparatuses 1. FIG. In this case, it is necessary to provide an adjustment mechanism (not shown) for adjusting the distance (eye width distance) between both eyepiece optical systems.

Further, by freely moving the above-described nose pad 5, the position of the image display device 1 can be adjusted relative to the observer in the front and rear, left and right, and up and down directions. The position of the optical pupil of the system 14 can be placed at the position of the observer's pupil. After the position adjustment, the optical pupil can be fixed at a good position by fixing the position of the nose pad 5 by the nose pad lock unit 6.

From the above, the nose pad 5 and the nose pad lock unit 6 at least have an adjustment mechanism (first adjustment) that adjusts the distance between the eyepiece optical system 14 (or optical pupil) of the video display device 1 and the pupil of the observer. The first adjustment mechanism may be configured independently of the second adjustment mechanism for adjusting the vertical and horizontal positions of the video display device 1. In this case, each position adjustment becomes easier.
<Embodiment 2>
Another embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, the same components as those in the first embodiment are denoted by the same member numbers, and the description thereof is omitted.
[Video display device]
FIG. 11 is a cross-sectional view showing a schematic configuration of the video display device 1b of the present embodiment, and FIG. 12 is a perspective view of the video display device 1b. The video display device 1b includes a light source unit 11 ′, an illumination optical system 12 ′, a display element 13 ′, an eyepiece optical system 14, and a polarizing plate 15. The display element 13 ′ is different from the display element 13 of the first embodiment, which is configured by a transmissive LCD, in that the display element 13 ′ is configured by a reflective LCD.

The light source unit 11 ′ is composed of a plurality of light sources 11, and in the present embodiment, the five light sources 11 are arranged in the horizontal direction (the eye width direction of the observer). Therefore, as shown in FIG. 13, the light emitting surfaces 11a of the individual light sources 11 are also arranged in the horizontal direction. Note that light in all emission wavelength regions of BGR is emitted from the same light emitting surface 11a, as in the first embodiment.

The size of the light source unit 11 ′, that is, the number of light sources 11 to be used may be determined by the size of the optical pupil P to be configured and the pupil magnification of the eyepiece optical system 14. Since the size of the light source 11 (the size of the LED chip) is generally almost determined, the optical pupil P having a bright optimal shape can be formed by arranging a plurality of light sources 11.

The illumination optical system 12 ′ includes a diffusion plate 33, a polarizing plate 34, a polarizing plate 35, and a mirror 36. The diffusing plate 33 and the polarizing plate 34 are disposed on the light source unit 11 ′ side with respect to the optical path of the image light from the display element 13 ′ toward the eyepiece optical system 14, and the polarizing plate 35 and the mirror 36 are disposed on the above optical path. On the other hand, it is arranged on the opposite side to the light source unit 11 ′.

The diffusing plate 33 is a unidirectional diffusing plate that diffuses incident light from the light source unit 11 ′ only in the horizontal direction, that is, in the arrangement direction of the plurality of light sources 11. Although the diffuser plate 33 (secondary light source) and the optical pupil P are in a substantially conjugate positional relationship, details will be described later. The polarizing plates 34 and 35 transmit, for example, P-polarized light in the incident light. The mirror 36 is constituted by, for example, a cylindrical concave mirror having power only in the vertical direction.

The polarizing plate 15 is disposed on the surface 41 a of the eyepiece prism 41, and transmits, for example, S-polarized light out of incident light (image light from the display element 13 ′) and enters the eyepiece prism 41. That is, the polarizing direction of the polarizing plate 15 and the polarizing plates 34 and 35 of the illumination optical system 12 ′ are orthogonal to each other.

According to the above configuration, the illumination light emitted from the light source unit 11 ′ is diffused in the horizontal direction by the diffusion plate 33 of the illumination optical system 12 ′. Then, only the P-polarized light is transmitted through the polarizing plate 34 and the polarizing plate 35 and is incident on the mirror 36, is reflected there, and is simultaneously collimated only in the vertical direction, is transmitted through the polarizing plate 35 again, and is incident on the display element 13 '. To do. In the display element 13 ′, incident light is modulated in accordance with image data. At this time, for example, in a pixel corresponding to white display, incident P-polarized light is converted into S-polarized light and emitted.

Image light (S-polarized light) emitted from the display element 13 ′ passes through the polarizing plate 15 and enters the eyepiece prism 41 of the eyepiece optical system 14 from the surface 41 a. The image light is guided while being totally reflected by the front and back surfaces 41 b and 41 c of the eyepiece prism 41, is diffracted and reflected by the HOE 43, and then enters the optical pupil P.

As in this embodiment, the optical pupil P can be expanded in the horizontal direction by using a light source unit 11 ′ composed of a plurality of light sources 11. Therefore, even when two video display devices 1b according to the present embodiment are used in front of both eyes of the observer, the video can be observed without adjusting the eye width for each observer. That is, by using the light source unit 11 ′, it is possible to form the optical pupil P that is long in the horizontal direction when observing the image. Therefore, the image display device 1 b according to the present embodiment is optimal for the binocular type HMD.

In the present embodiment, the illumination optical system 12 ′ includes the diffusion plate 33, and the incident light from the light source unit 11 ′, that is, the light from the plurality of light sources 11 is diffused by the diffusion plate 33. . When the plurality of light sources 11 are discretely arranged, luminance unevenness occurs in the optical pupil. However, the above-described luminance unevenness can be reduced by diffusing light from the plurality of light sources 11 with the diffusion plate 33. it can.

In particular, the diffusion plate 33 diffuses incident light only in the arrangement direction (horizontal direction) of the plurality of light sources 11, so that luminance unevenness generated in the arrangement direction of the plurality of light sources 11 can be reliably reduced. At the same time, since incident light is not diffused in directions other than the above, unnecessary diffusion can be reduced to improve the light utilization efficiency, and a bright image can be observed.

In the present embodiment, the diffusion plate 33 is disposed for the purpose of eliminating luminance unevenness when a plurality of light sources 11 are disposed. However, light in all emission wavelength regions of the BGR is emitted from the same light emitting surface 11a. This is the same as in the first embodiment, and is the same as in the first embodiment in that a diffusion plate for eliminating color unevenness caused by the difference in the BGR emission position is unnecessary.

Further, in the present embodiment, the diffusion plate 33 and the optical pupil P are in a substantially conjugate positional relationship. In addition, the positional relationship is substantially conjugate refers to a positional relationship in which a substantially optically conjugate relationship is established in at least one of the horizontal direction and the vertical direction. In the present embodiment, since the incident light is diffused by the diffusion plate 33 in the horizontal direction, it is not optically substantially conjugate, but in the vertical direction, it is optically substantially conjugate and is approximately positionally. A conjugate relationship is established. With such a substantially conjugate positional relationship, the light diffused by the diffusion plate 33 can be efficiently guided to the optical pupil P. Therefore, when the observer's pupil is positioned at the position of the optical pupil, the observer Can observe bright images without uneven brightness.

Further, since the eyepiece optical system 14 of the present embodiment is a non-axisymmetric optical system in the vertical direction (a symmetric plane is a plane perpendicular to the plane of the optical pupil P and includes the vertical direction), an image is generated by dispersion of the HOE 43. Degradation occurs. However, since the diffusing plate 33 and the optical pupil P are optically approximately conjugate in the vertical direction, it is possible to suppress the deterioration of the video in the vertical direction and to efficiently guide the illumination light to the observer's pupil.

Further, in the present embodiment, the light incident on the display element 13 ′ by the arrangement of the polarizing plates 34 and 35 is P-polarized light, so that the surface reflection at the display element 13 is made as compared with the case where incident light is S-polarized light. (Fresnel loss) can be suppressed. That is, in the case of P-polarized light, unlike S-polarized light, there is an incident angle (Brewster angle) at which the reflectance at the surface becomes zero, so that it is possible to suppress light amount loss. As a result, it is possible to avoid a reduction in video quality due to light loss.

In addition, since the polarizing directions of the polarizing plates 34 and 35 and the polarizing plate 15 are orthogonal to each other, the light transmitted through the polarizing plate 34 does not pass through the polarizing plate 15 even if it directly reaches the polarizing plate 15. Further, even if the light transmitted through the polarizing plate 34 is reflected on the surface of the polarizing plate 35 and reaches the polarizing plate 15, it does not pass through the polarizing plate 15. Therefore, it is possible to avoid the occurrence of ghosts and flares due to unnecessary light, and to reliably avoid the deterioration of the image quality.
[About HMD]
FIG. 14 is a perspective view showing a schematic configuration of the HMD of the present embodiment. The HMD of this embodiment is different from the HMD of Embodiment 1 in that it includes two video display devices 1b and 1b, and the support means 2 supports the two video display devices 1b and 1b. Yes. That is, the HMD of this embodiment is of a type that observes an image with both eyes.

Since the image display device 1b of the present embodiment has a long optical pupil in the horizontal direction, light in each emission wavelength region of BGR is emitted from the same light emitting surface 11a (see FIG. 13). There is no color unevenness in the pupil, and a bright image can be observed without uneven brightness due to the arrangement of the plurality of light sources 11 and the diffusion plate 33. Therefore, the video display device 1b according to the present embodiment is optimal for an HMD for binocular observation.

In addition, for example, when the optical pupil in the horizontal direction is small, or color unevenness occurs at a position shifted from the center in the horizontal direction even if the optical pupil is long, in order to observe a good image with both eyes The eye width adjustment between the left and right optical units (between the video display devices 1b and 1b) is necessary. For this reason, the structure of the nose pads 5 and 5 between the optical system holder, particularly the left and right optical units, is complicated and tends to be large. However, as in this embodiment, by generating a long optical pupil in the horizontal direction without color unevenness, it is possible to easily realize a configuration without eye width adjustment, which is a lightweight and highly wearable binocular type. HMD can be realized.

In the above, the fluorescent type shown in FIG. 3 or FIG. 4 is used as the light source 11 that emits light in all emission wavelength regions of BGR from the same light emitting surface 11a. However, the light source 11 is limited to this type. It is not done. For example, the light source 11 may be configured by stacking BGR semiconductor light emitting elements (LEDs), and may be configured by a stacked type that emits white (three colors of BGR) light from the same light emitting surface 11a. . When the stacked type light source 11 is used, since the half-value wavelength width of the emission intensity peak is narrower than that of the fluorescent type, there is an effect of reducing unnecessary flare light. The laminated light source 11 will be briefly described as follows.

FIG. 15 is a cross-sectional view showing a schematic configuration of a stacked type light source 11. The light source 11 includes a substrate 71, a GaN buffer layer 72, an undoped GaN layer 73, an n-type contact / cladding layer 74 made of Si-doped GaN, a superlattice layer 75, an active layer 76 made of a multiple quantum well structure, A p-type cladding layer 77 made of Mg-doped AlGaN and a p-type contact layer 78 made of Mg-doped GaN are sequentially stacked. The active layer 76 includes a plurality of barrier layers 76a and well layers 76B, 76G, and 76R made of InGaN. Of all the well layers 76B, 76G, and 76R, the well layer 76B has the smallest In content, and the well layer 76R has the largest In content. The well layers 76G, 76R, and 76B are stacked in this order from the n-type contact / cladding layer 74 side, and are sandwiched between the barrier layers 76a (each stacked via the barrier layer 76a). Have been). A p-side transparent electrode 79 and a p-side pad electrode 80 are formed in this order on the p-type contact layer 78, and an n-electrode 81 is formed on the n-type contact layer / cladding layer 74. In this configuration, light with wavelengths of 448 nm, 500 nm, and 570 nm, for example, is emitted from the well layers 76B, 76G, and 76R, and the surface of the p-side transparent electrode 79 (the surface opposite to the p-type contact layer 78) is BGR. It becomes the same light emission surface 11a which light-emits this light.

In each type of light source 11 described above, RGB light is uniformly emitted from the light emitting surface 11a on the surface (upper side) of the element.

In addition, although the example which applied the video display apparatus to HMD was demonstrated above, the video display apparatus of this invention is applicable also to other apparatuses, such as a head up display (HUD), for example. For example, when a vehicle information display system capable of displaying a large amount of information is realized by a HUD, the video display device of the present invention can be applied to such a HUD.

Of course, it is possible to appropriately combine the configurations described in the respective embodiments to configure the video display device and thus the HMD or HUD.

The video display device of the present invention can be used for, for example, an HMD or HUD using a HOE as a combiner.

DESCRIPTION OF SYMBOLS 1, 1a, 1b Image | video display apparatus 2 Support means 11 Light source 11a Light emission surface 11 'Light source unit 12, 12' Illumination optical system 13, 13 'Display element 14 Eyepiece optical system (observation optical system)
33 Diffusion plate 43 HOE (Hologram optical element)
43a Hologram photosensitive material 61B, 61G, 61R Point light source (exposure light source)
P Optical pupil

Claims (15)

A light source;
A display element that modulates incident light and displays an image;
An illumination optical system for guiding light from the light source to the display element;
An observation optical system for guiding the image light from the display element to an optical pupil,
The observation optical system is a video display device having a volume phase type reflection type hologram optical element for diffracting and reflecting video light from the display element in an optical pupil direction,
The light emitted from the light source emits one light in each of the first wavelength region of 400 nm to less than 500 nm, the second wavelength region of 500 nm to less than 570 nm, and the third wavelength region of 570 nm to less than 700 nm. It has an intensity peak wavelength and an emission wavelength region including the emission intensity peak wavelength,
All the light in the emission wavelength region is emitted from the same light emitting surface of the light source,
When a light beam emitted from the center of the display element and incident on the center of the optical pupil through the hologram optical element is a screen center chief ray,
All of the emission wavelength regions include a diffraction efficiency peak wavelength of the hologram optical element with respect to the central chief ray of the screen. When the diffraction efficiency peak wavelength is λmax, the emission intensity peak wavelength is λpeak, and the half-value wavelength width of the emission intensity peak wavelength is Δλ, in the second wavelength region,
| Λmax−λpeak | / Δλ <0.4
The video display device according to claim 1, wherein: In all the first to third wavelength regions,
| Λmax−λpeak | / Δλ <0.4
The video display device according to claim 2, wherein: The emission intensity peak values of the first wavelength region, the second wavelength region, and the third wavelength region are denoted as E _B , E _G , and E _R , respectively.
Between the emission intensity peak wavelength in the first wavelength range and the emission intensity peak wavelength in the second wavelength range, the emission intensity peak wavelength in the second wavelength range and the emission intensity peak wavelength in the third wavelength range When the emission intensity bottom values at which the emission intensity between and is the lowest are E _BG and E _GR , respectively.
E _B / E _BG > 2
E _G / E _BG > 2
E _G / E _GR > 2
E _R / E _GR > 2
The video display apparatus according to claim 1, wherein all of the above are satisfied. 5. The image display device according to claim 1, wherein the same light emitting surface of the light source and the optical pupil are in a substantially conjugate positional relationship. 5. The video display device according to claim 1, wherein a plurality of the light sources are provided. The image display device according to claim 6, further comprising a diffusion plate that diffuses light from the plurality of light sources. The image display device according to claim 7, wherein the diffusion plate diffuses incident light only in an arrangement direction of the plurality of light sources. The image display device according to claim 7 or 8, wherein the diffusion plate and the optical pupil are in a substantially conjugate positional relationship. 10. One exposure light source for exposing a hologram photosensitive material used for manufacturing the hologram optical element is disposed on a surface including an optical pupil of the observation optical system during image observation. The video display device according to any one of the above. 11. The image display device according to claim 1, wherein diffraction efficiency in each wavelength region of the hologram optical element is set according to emission intensity in each wavelength region of the light source. . The diffraction efficiency in each wavelength region of the hologram optical element is highest in a wavelength region where the light emission intensity of the light source is the lowest, and lowest in a wavelength region where the light emission intensity of the light source is highest. The video display device described. The diffraction efficiency in each wavelength region of the hologram optical element is such that when the display element displays white and the screen center of the display image is observed from the optical pupil center, the color of the screen center is in the XYZ color system. In XY chromaticity coordinates,
(X, Y) = (0.32 ± 0.05, 0.33 ± 0.05)
The video display device according to claim 11, wherein the video display device is set to have a color within a range of. The light emission intensity peak wavelengths of the light sources in the first wavelength region, the second wavelength region, and the third wavelength region are λ _B , λ _G , and λ _R , respectively, and the half-value wavelength width of the light emission intensity peak is When ΔB, ΔG, and ΔR, respectively,
0.05λ _B <ΔB <0.2λ _B
0.05λ _G <ΔG <0.2λ _G
0.05λ _R <ΔR <0.2λ _R
The video display device according to claim 1, wherein: The video display device according to any one of claims 1 to 14,
And a support means for supporting the video display device in front of the observer's eyes.

Images