WO2010134374A1 - Image display apparatus, head-mounted display, and head-up display - Google Patents

Abstract

Provided is an image display apparatus in which a change in a color tone of an image which is sensed by a viewer, depending on the position of a pupil is suppressed in consideration of a human's relative luminous efficiency. To this end, the image display apparatus is configured to shift the diffraction peak wavelength of image light incident upon a pupil of a viewer when the pupil of the viewer is deviated from the center of an optical pupil, wherein a change in the intensity of light emitted from a light source in B and R wavelength ranges is opposite a change in a human's relative luminous efficiency. Namely, the intensity of light emitted from the light source is set to be low on the long wavelength side in the B wavelength range, and is set to be high on the long wavelength side in the R wavelength range.

Description

Video display device, head-mounted display, and head-up display

The present invention relates to a video display device, and a head mounted display (hereinafter also referred to as HMD) and a head-up display (hereinafter also referred to as HUD) provided with the video display device.

2. Description of the Related Art Conventionally, an image display apparatus that uses a volume phase type reflection hologram optical element (hereinafter also referred to as HOE) having an optical power equivalent to that of an aspherical concave mirror as a combiner and can superimpose an image and the outside world for observation. Various proposals have been made including, for example, Patent Document 1.

FIG. 16 shows a schematic configuration of a conventional general video display device using HOE. In this video display device, red (R), green (G), and blue (B) light emitted from the light source 101 is collected by the condenser lens 102 and incident on the display element 103, where image data is obtained. Is modulated according to. RGB image light from the display element 103 is diffracted and reflected by the HOE 105 of the eyepiece optical system 104 and guided to 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. Further, the volume phase type reflection type HOE 105 has high wavelength selectivity and transmits almost all the external light, so that the observer can observe the external world see-through simultaneously with the above-mentioned image.

JP 2008-191527 A

By the way, the intensity of light felt when an observer observes an image is referred to as observation illuminance. This observation illuminance is determined by the image light intensity and the human specific visual sensitivity. The former image light intensity is substantially determined by the product of the radiated light intensity of the light source 101 and the diffraction efficiency of the HOE 105. On the other hand, as shown in FIG. 17, the latter specific luminous efficiency is the highest near the wavelength of 555 nm, and decreases from the wavelength toward the long wavelength side and the short wavelength side.

Since the observation illuminance is affected not only by the image light intensity but also by the relative visibility, in the video display device designed without considering the relative visibility, the color of the image that the viewer perceives depending on the pupil position of the viewer. There arises a problem that (tone, color tone, color balance) changes. Hereinafter, this point will be described in more detail.

FIG. 18 shows an example of a manufacturing optical system of the HOE 105 used in the video display device of FIG. The volume phase type reflective HOE 105 is emitted from one point light source 201 (spherical wave) disposed at the center of the optical pupil P of the eyepiece optical system 104 in use and emitted from the other point light source 301. It is manufactured by exposing the hologram photosensitive material 105a with a light beam shaped into a desired wavefront by the optical system 302 and recording the interference fringes of these two light beams as a refractive index distribution. At this time, the HOE 105 that diffracts the RGB image light can be produced by exposing the hologram photosensitive material 105a with the RGB light beams.

Here, in FIG. 16, the axis that optically connects the center of the display surface of the display element 103 and the center of the optical pupil P is an optical axis, and the surface includes the optical axis of incident light and the optical axis of reflected light in the HOE 105. Is the optical axis incident surface. In the plane of the optical pupil P, a direction perpendicular to the optical axis and parallel to the optical axis incidence surface is defined as a Y direction, and a direction in which the diffraction angle of the HOE 105 decreases in the Y direction is defined as a positive direction.

FIG. 19 shows the diffraction characteristics of the HOE 105 for each pupil position in the Y direction for each of RGB. When the exposure wavelength of the hologram photosensitive material 105a is, for example, 476.5 nm, 532 nm, and 647 nm, in the image display device using the HOE 105 described above, the diffraction peak of the image light reaching the center (Y = 0) of the optical pupil P The wavelengths are 467 nm, 521.4 nm, and 634.1 nm for RGB on the entire screen (at any angle of view) when the shrinkage of the hologram photosensitive material 105a during exposure is 2%.

On the other hand, the diffraction peak wavelength of the image light reaching the position shifted in the Y direction from the center in the plane of the optical pupil P changes according to the Bragg conditional expression. That is, the diffraction peak wavelength of the image light reaching the position shifted from the center of the optical pupil P to the Y direction positive side (for example, Y = 1, 2) is shifted to the long wavelength side, and from the center of the optical pupil P to the Y direction. The diffraction peak wavelength of the image light reaching the position shifted to the negative side (for example, Y = −1, −2) is shifted to the short wavelength side.

However, from FIG. 19, it can be said that the maximum diffraction efficiency in the HOE 105 of the image light reaching each pupil position is almost the same for any pupil position. FIG. 20 shows the relationship between the pupil position in the Y direction and the ratio of the maximum diffraction efficiency of RGB. Also from FIG. 20, the ratio of the maximum diffraction efficiency of RGB is almost the same regardless of the pupil position. (It is almost 1). That is, the ratio of the maximum diffraction efficiency of image light reaching other pupil positions to the maximum diffraction efficiency of image light reaching the pupil center is approximately 1 for both RGB.

Therefore, as shown in FIG. 21, when the ratio of the radiated light intensity of RGB of the light source 101 (light emission intensity ratio) is almost the same for any pupil position in the Y direction, as shown in FIG. Since the relationship between the pupil position and the ratio of the maximum diffraction efficiency of RGB is substantially constant, as shown in FIG. 22, the intensity ratio of RGB image light reaching the observer's pupil depends on the pupil position in the Y direction. Almost the same. That is, the intensity ratio of the image light reaching each pupil position to the light reaching the pupil center is substantially the same between RGB.

On the other hand, FIG. 23 shows the relationship between the pupil position in the Y direction and the relative visibility for each of RGB. That is, FIG. 23 shows a portion corresponding to the wavelength range of the image light reaching the negative side end from the positive side end in the Y direction of the optical pupil P for RGB in the relative visibility curve shown in FIG. The extracted pupils are aligned in the Y direction in RGB. Taking white balance at the center of the pupil (Y = 0) (determining the RGB radiated light intensity of the light source 101) and using the relative luminous sensitivity at the center of the pupil as a reference (the ratio of relative luminous sensitivity at the center of the pupil is R: G). : B = 1: 1: 1), the relationship between the pupil position in the Y direction and the ratio of RGB relative luminous sensitivities is as shown in FIG. FIG. 25 shows the relationship between the pupil position in the Y direction and the ratio of RGB observation illuminance when white balance is achieved at the center of the pupil. The ratio of RGB observation illuminance in FIG. This is shown in FIG.

As described above, when the intensity ratio of the image light reaching each pupil position to the image light reaching the pupil center is substantially the same for all RGB, the observer's pupil position is shifted in the Y direction from FIG. It can be seen that the color of the image perceived by the observer changes. That is, at the center of the pupil (Y = 0), white can be observed when white is displayed, but at the position of Y = −2, the observer can see the image red when displaying white. At the position of Y = 2, the observer feels the image blue-green when white is displayed.

The present invention has been made to solve the above-described problems, and its purpose is to minimize the change in the color of the image perceived by the observer depending on the pupil position in consideration of human specific visibility. It is an object to provide a video display device capable of performing the above and an HMD and HUD including the video display device.

The image display device of the present invention includes a light source, a display element that modulates light from the light source and displays an image, and a volume phase reflection type that diffracts and reflects the image light from the display element and guides it to an optical pupil. And an observation optical system having the hologram optical element, wherein the light source has an intensity peak of radiated light in each of the red, green, and blue wavelength ranges, and the red, green, blue ΛRlong and λGlong of the diffraction peak wavelengths of image light incident on the center of the optical pupil from the respective positions on the display surface of the display element through the hologram optical element in the respective wavelength regions , ΛBlong, and λRshort, λGshort, and λBshort on the shortest wavelength side,
λRlong / λRshort <1.05
λGlong / λGshort <1.05
λBlong / λBshort <1.05
Satisfied,
The direction in which the diffraction peak wavelength shifts in the plane of the optical pupil is the Y direction, the direction in which the diffraction peak wavelength shifts to the long wavelength side in the Y direction is positive, and the Y of the optical pupil is in each of the red and blue wavelength regions. The _radiated light intensity of the light source for the diffraction peak wavelength of the image light incident on the positive end of the direction is E _RY and E _BY , respectively, and the image light incident on the negative end of the optical pupil in the Y direction the emitted light intensity of the light source for the diffraction peak wavelengths E _R-Y, when the _{E B-Y,}
E _BY -E _BY <0
E _RY -E _RY> 0
It is characterized by satisfying.

The video display device of the present invention is
_{E RY / E RY> E BY} / E BY
It is desirable to satisfy

The video display device of the present invention is
_{(E RY / E RY) /} (E BY / E BY) <2
It is desirable to satisfy

In the image display device of the present invention, when the radiated light intensity of the light source with respect to the diffraction peak wavelength of the image light incident on the center of the optical pupil in each of the red and blue wavelength ranges is E _R0 and E _B0 ,
_{(E BY -E B0) × (} E B0 -E BY)> 0
_{(E RY -E R0) × (} E R0 -E RY)> 0
It is desirable to satisfy

In the image display device of the present invention, in the green wavelength range, the radiated light intensity of the light source for the diffraction peak wavelength of the image light incident on the positive end of the optical pupil in the Y direction is E _GY, and when the emitted light intensity of the light source for the diffraction peak wavelength of the image light incident was E _G-Y on the end of the negative side in the Y direction,
E _GY -E _GY <0
It is desirable to satisfy

The video display device of the present invention is
_{E RY / E RY> E GY} / E GY
It is desirable to satisfy

The video display device of the present invention is
_{(E RY / E RY) /} (E GY / E GY) <4
It is desirable to satisfy

In the image display device of the present invention, when the emitted light intensity of the light source for the diffraction peak wavelength of the image light incident on the center of the optical pupil in the green wavelength region is E _G0 ,
_{(E GY -E G0) × (} E G0 -E GY)> 0
It is desirable to satisfy

In the video display device of the present invention, it is desirable that the light source and the optical pupil are conjugate.

In the video display device of the present invention, it is desirable that light in each wavelength region of red, green, and blue is emitted from the same region of the light source.

The head-mounted display of the present invention may be configured to include 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 head-up display of the present invention includes the above-described video display device of the present invention, and the hologram optical element of the video display device may be held on a substrate arranged in the field of view of the observer. Good.

Observation in a configuration satisfying the conditional expressions of λRlong / λRshort <1.05, λGlong / λGshort <1.05, and λBlong / λBshort <1.05, that is, when the observer's pupil is shifted from the center of the optical pupil. in the structure the diffraction peak wavelength of the image light incident on the person of the pupil is _shifted, is satisfied _{E BY -E BY <0, E} RY -E RY> the conditional expressions 0, B and R A change in the emitted light intensity of the light source in the wavelength range is opposite to a change in human specific luminous efficiency. That is, the emitted light intensity of the light source is low on the long wavelength side in the B wavelength range and high on the long wavelength side in the R wavelength range.

In this way, by setting the radiated light intensity of the light source in consideration of the relative visibility in the B and R wavelength regions, the observer's pupil is shifted in either the positive or negative direction in the Y direction from the center of the optical pupil. However, it is possible to suppress a change in the RGB observation illuminance ratio in consideration of the relative visibility. As a result, it is possible to suppress a change in the color of the image perceived by the observer due to a difference in the pupil position in the Y direction.

Although the HOE diffraction efficiency also affects the observation illuminance, as described above, the maximum diffraction efficiency of the HOE for the light reaching each pupil position is substantially constant, so that the RGB observation is performed at any pupil position in the Y direction. There is no change in that the change in the illuminance ratio can be reduced, and the effect of the present invention that can reduce the change in the color of the observation image due to the pupil position is still obtained.

It is explanatory drawing which shows the emitted light intensity characteristic of the light source of the video display apparatus of one Embodiment of this invention. It is a perspective view which shows the structure of the outline of HMD to which the said video display apparatus is applied. It is sectional drawing which shows the schematic structure 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 sectional drawing which shows the schematic structure of the lamination | stacking type light source which is another 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 showed the relationship between the pupil position of a Y direction, and observation illumination intensity ratio on the basis of G observation illumination intensity. It is explanatory drawing which expands and shows the principal part of the manufacturing optical system of HOE applied to the video display apparatus of other embodiment of this invention. It is explanatory drawing which shows the emitted light intensity characteristic of the light source of the said video display apparatus. It is explanatory drawing which showed the relationship between the pupil position of a Y direction, and observation illumination intensity ratio on the basis of G observation illumination intensity. It is sectional drawing which shows the schematic structure of the video display apparatus of further another embodiment of this invention, and HUD provided with the same. 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 emitted light intensity characteristic of the light source of the said video display apparatus. It is explanatory drawing which showed the relationship between the pupil position of a Y direction, and observation illumination intensity ratio on the basis of G observation illumination intensity. It is sectional drawing which shows the structure of the outline of the conventional common video display apparatus using HOE. It is explanatory drawing which shows the relationship between a wavelength and specific luminous efficiency. It is explanatory drawing which shows an example of the manufacturing optical system of HOE used for the said video display apparatus. It is explanatory drawing which shows the diffraction characteristic of RGB of HOE. It is explanatory drawing which shows the relationship between the pupil position of a Y direction, and the ratio of RGB maximum diffraction efficiency. It is explanatory drawing which shows the relationship between the pupil position of a Y direction, and the radiated light intensity ratio of RGB of a light source. It is explanatory drawing which shows the relationship between the pupil position of a Y direction, and the pupil arrival light intensity ratio of RGB. It is explanatory drawing which shows the relationship between the pupil position of a Y direction, and relative luminous sensitivity about each of RGB. It is explanatory drawing which shows the relationship between the pupil position of a Y direction, and the ratio of the relative luminous sensitivity of RGB. It is explanatory drawing which shows the relationship between the pupil position of a Y direction, and the ratio of the observation illumination intensity of RGB. It is explanatory drawing which shows the relationship between the pupil position of a Y direction, and the ratio of RGB observation illumination intensity on the basis of G observation illumination intensity.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to the drawings.

(About HMD)
FIG. 2 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 has a housing 3 that contains at least a light source 11 and a display element 13 (both see FIG. 3). The housing 3 holds a part of the eyepiece optical system 14. The eyepiece optical system 14 is configured by bonding an eyepiece prism 31 and a deflection prism 32, and has a shape like one lens of a pair of glasses (lens for right eye in FIG. 2) 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 means 2 is a support mechanism corresponding to a spectacle frame (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 HMD is mounted on the observer's head and the nose pad 5 is fixed by the nose pad lock unit 6 and an image is displayed 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 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.

(About video display device)
Next, details of the video display device 1 will be described. FIG. 3 is a cross-sectional view showing a schematic configuration of the video display device 1 of the present embodiment. The video display device 1 includes a light source 11, an illumination optical system 12, a display element 13, and an eyepiece optical system 14. In the present embodiment, the observation angle in the horizontal direction is, for example, ± 13 °, and the observation angle in the vertical direction is, for example, ± 7.5 °, so that a so-called wide screen image can be observed. .

Here, for convenience of explanation below, an axis that optically connects the center of the display surface of the display element 13 and the center of the optical pupil P formed by the eyepiece optical system 14 is an optical axis, and the eyepiece optical system 14 A surface including an optical axis of incident light and an optical axis of reflected light in the HOE 33 described later is defined as an optical axis incident surface. In the plane of the optical pupil P, a direction perpendicular to the optical axis and parallel to the optical axis incidence surface is defined as a Y direction, and a direction in which the diffraction angle of the HOE 33 decreases in the Y direction is defined as a positive direction. Note that the Y direction in the optical pupil P also corresponds to the vertical direction perpendicular to the eye width direction (left-right direction) of the observer.

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 the same region 11a (FIGS. 4 and 5). , See FIG. 6). The configuration of the light source 11 and details of the light emission characteristics will be described later. The light source 11 (particularly the region 11a) is disposed at a position substantially conjugate with the optical pupil P.

The size of the region 11a of the light source 11 is, for example, 1 mm in the vertical direction × 2 mm in the horizontal direction, and the magnification of the optical pupil P 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 illumination optical system 12 is an optical system that condenses the light from the light source 11 and guides it to the display element 13, and includes, for example, a mirror 21 having a concave reflecting surface. The display element 13 displays an image by modulating light incident from the light source 11 via the illumination optical system 12 in accordance with image data, and is configured by, for example, a transmissive LCD. The display element 13 is arranged such that the long side direction of the rectangular display screen is the horizontal direction (direction perpendicular to the paper surface of FIG. 3; 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), and includes an eyepiece prism 31, a deflection prism 32, and a HOE 33. And is configured.

The eyepiece prism 31 totally reflects the image light from the display element 13 and guides it to the optical pupil P through the HOE 33, while transmitting the external light to the optical pupil P. Together with the deflection prism 32, For example, it is made of an acrylic resin. The eyepiece prism 31 is formed in a shape in which a lower end portion of a parallel plate is wedge-shaped. An upper end surface of the eyepiece prism 31 is a surface 31a as an incident surface for image light, and two surfaces positioned in the front-rear direction are surfaces 31b and 31c parallel to each other.

The deflection prism 32 is configured by a substantially U-shaped parallel plate in plan view (see FIG. 2), and when attached to the lower end portion and both side surface portions (left and right end surfaces) of the eyepiece prism 31, the eyepiece prism. 31 and a substantially parallel flat plate. The deflection prism 32 is provided adjacent to or adhering to the eyepiece prism 31 so as to sandwich the HOE 33 therebetween. Thereby, the refraction when the external light passes through the wedge-shaped lower end of the eyepiece prism 31 can be canceled by the deflecting prism 32, and distortion of the external image observed through the see-through can be prevented. .

The HOE 33 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, and a volume phase type reflection hologram. It is an optical element, and is formed on a surface 31 d that is a joint surface with the deflection prism 32 in the eyepiece prism 31. The HOE 33 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. In the present embodiment, the diffraction peak wavelength of the HOE 33 for light incident on the center of the optical pupil P is, for example, 467 nm, 521.4 nm, and 634.1 nm, as will be described later.

In the image display device 1 having the above-described configuration, the light emitted from the light source 11 is reflected and collected by the mirror 21 of the illumination optical system 12 and is substantially collimated and incident on the display element 13 where it is modulated and imaged. It is emitted as light. The image light from the display element 13 enters the inside of the eyepiece prism 31 of the eyepiece optical system 14 from the surface 31a, and then is totally reflected at least once by the surfaces 31b and 31c and enters the HOE 33.

The HOE 33 has wavelength selectivity that functions as a diffraction element that independently diffracts light in each wavelength region of BGR emitted from the light source 11 for each wavelength region. It is designed to function as a concave reflecting surface for light. Therefore, the light incident on the HOE 33 is diffracted and reflected there and reaches the optical pupil P. At the same time, external light passes through the HOE 33 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 13 as an enlarged virtual image, and at the same time, can observe the outside world in a see-through manner. it can. 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 the structure of the light source)
Next, the details of the configuration of the light source 11 will be described. FIG. 4 is a cross-sectional view illustrating a configuration example of the light source 11. The light source 11 includes an LED 42 that is a semiconductor light emitting element that emits B light, a green phosphor 43G that is excited by B light and emits G light, and an R light that is excited by B light. A red phosphor 43R that emits light. The LED 42 is mounted on a substrate 44 and is connected to an electrode on the substrate 44 by a wire 45. In the housing 41, the LED 42, the green phosphor 43G, and the red phosphor 43R are sealed with a first sealing material 46 that is a molding material such as an epoxy resin, and further, with respect to the first sealing material 46 The side opposite to the substrate 44 is sealed with a second sealing material 47. As a result, the surface of the second sealing material 47 (the surface opposite to the substrate 44) is the same region 11a that emits light in each of the RGB wavelength regions.

Further, the light source 11 may be configured as shown in FIG. FIG. 5 is a cross-sectional view showing another configuration example of the light source 11. The light source 11 of FIG. 5 replaces the LED 42 of the light source 11 of FIG. 4 with an LED 42 ′, newly provides a blue phosphor 43B, and replaces the green phosphor 43G and the red phosphor 43R with the green phosphor 43G ′ and the red phosphor, respectively. It is replaced with 43R ′. The LED 42 ′ is a semiconductor light emitting element that emits near-ultraviolet light, and the blue phosphor 43B, the green phosphor 43G ′, and the red phosphor 43R ′ are respectively excited by near-ultraviolet light to emit B light, G light, R It is a phosphor that emits light.

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 region 11a. When the laminated type light source 11 is used, since the half-value wavelength width of the radiation intensity peak is narrower than that of the fluorescent type shown in FIGS. 4 and 5, there is an effect that unnecessary flare light can be further reduced. The laminated light source 11 will be briefly described as follows.

FIG. 6 is a cross-sectional view showing a schematic configuration of a stacked type light source 11. The light source 11 includes a GaN buffer layer 52, an undoped GaN layer 53, an n-type contact / cladding layer 54 made of Si-doped GaN, a superlattice layer 55, an active layer 56 made of a multiple quantum well structure, A p-type cladding layer 57 made of Mg-doped AlGaN and a p-type contact layer 58 made of Mg-doped GaN are sequentially stacked. The active layer 56 includes a plurality of barrier layers 56a and well layers 56B, 56G, and 56R made of InGaN. Of all the well layers 56B, 56G, and 56R, the well layer 56B has the smallest In content and the well layer 56R has the largest In content. The well layers 56G, 56R, and 56B are stacked in this order from the n-type contact / cladding layer 54 side, and are sandwiched between the barrier layers 56a (each stacked via the barrier layer 56a). Have been). A p-side transparent electrode 59 and a p-side pad electrode 60 are sequentially formed on the p-type contact layer 58, and an n-electrode 61 is formed on the n-type contact layer / cladding layer 54. In this configuration, light having a wavelength of, for example, 448 nm, 500 nm, and 570 nm is emitted from the well layers 56B, 56G, and 56R, and the surface of the p-side transparent electrode 59 (the surface opposite to the p-type contact layer 58) is BGR. It becomes the same area | region 11a which radiates | emits light.

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

Since the light source 11 (particularly the region 11a) is disposed at a position substantially conjugate with the optical pupil P as described above, each light of BGR emitted from the same region 11a can be efficiently guided to the optical pupil P. it can. Therefore, no matter where the optical pupil P is located, the observer can observe a bright and high-quality image.

Further, by adopting a configuration in which light in each wavelength region of RGB is emitted from the same region 11a in the light source 11, the same distribution as in FIGS. 21 and 22 can be easily realized. That is, the distribution of the radiated light intensity of the light source 11 (the relationship between the pupil position and the radiated light intensity) is aligned in RGB, and the intensity distribution of the image light reaching the optical pupil P (the relationship between the pupil position and the image light intensity) is RGB. Can be almost aligned. As a result, the setting of the radiated light intensity of the present invention, which will be described later, in consideration of the relative visibility is more effective.

(About manufacturing method of HOE)
Next, a method for manufacturing the above HOE 33 will be described. FIG. 7 is an explanatory view showing, in an enlarged manner, main parts of the manufacturing optical system of the HOE 33. As shown in FIG. The HOE 33 which is a reflection type color hologram is produced by exposing the hologram photosensitive material 33a on the substrate (eyepiece prism 31) using two light beams for each BGR. Examples of the hologram photosensitive material include a photopolymer, a silver salt material, and dichromated gelatin. Among them, a photopolymer that can be manufactured by a dry process is preferable. One of the two light beams is irradiated from the opposite side of the substrate to the hologram photosensitive material 33a. This light beam will be referred to as object light. The other light beam is irradiated from the substrate side to the hologram photosensitive material 33a, and this light beam is referred to as reference light.

In the optical system on the object light generation side, RGB divergent light from the point light source 71 (object light side light source) is shaped into a predetermined wavefront by a free-form surface mirror 72, which is a reflection surface having optical power, and is planarly reflected. After being reflected by the mirror 73, the hologram photosensitive material 33 a is irradiated through the color correction prism 74. Note that the surface 74a that is the incident surface of the object light in the color correction prism 74 is generated due to refraction of the image light on the surface 31a of the eyepiece prism 31 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, the color correction prism 74 is desirably disposed in close contact with the hologram photosensitive material 33a or is disposed via emulsion oil or the like in order to prevent ghosts due to surface reflection.

On the other hand, in the optical system on the reference light generation side, RGB divergent light (for example, spherical wave) from the point light source 81 (reference light side light source) is irradiated from the eyepiece prism 31 side to the hologram photosensitive material 33a as reference light. At this time, the point light source 81 is arranged at the center of the optical pupil P for all of RGB.

In this way, by exposing the hologram photosensitive material 33a with two light beams of object light and reference light for each of RGB, interference fringes are formed in the hologram photosensitive material 33a by interference of the two light beams, and the HOE 33 is manufactured. . At this time, the exposure with two light beams may be performed simultaneously for RGB or sequentially.

As described above, the point light source 81 at the time of exposure is arranged at the center of the optical pupil P, and the HOE 33 is manufactured. Thus, in the eyepiece optical system 14 including the HOE 33, aberration is caused between the light source 11 and the optical pupil P. If corrected properly, when the observer's pupil is positioned at the center of the optical pupil P, the illumination light (image light) is reliably diffracted and reflected by the HOE 33 and reaches the observer's pupil at all angles of view. To do. Therefore, the observer can observe a bright and high-quality image over the entire screen.

Here, the exposure wavelengths of RGB are, for example, 647 nm, 532 nm, 476.5 nm, and the shrinkage rate in the thickness direction of the hologram photosensitive material 33a is, for example, 2%. In this case, the diffraction peak wavelength of the HOE 33 for light passing through the center of the optical pupil P during reproduction is as shown in Table 1. In each of the RGB wavelength ranges, the longest wavelength side of the diffraction peak wavelengths of the image light incident on the center of the optical pupil P via the HOE 33 from each position on the display surface of the display element 13 is λRlong ( nm), λGlong (nm), and λBlong (nm), and those on the shortest wavelength side are λRshort (nm), λGshort (nm), and λBshort (nm), respectively.

In this embodiment, the point light source 81 arranged on the optical pupil P side when the HOE 33 is manufactured is arranged at the center of the optical pupil P. Therefore, in Table 1, λRlong / λRshort = λGlong / λGshort = λBlong / λBshort = It is 1. However, even if the point light source 81 is arranged so as to deviate from the optical pupil P within a range that satisfies the following conditional expressions (1), (2), and (3), the effect of the present invention can be achieved by setting the radiated light intensity described later. Can be obtained. That is,
λRlong / λRshort <1.05 (1)
λGlong / λGshort <1.05 (2)
λBlong / λBshort <1.05 (3)
It is.

Table 2 shows diffraction peak wavelengths of image light that is diffracted and reflected by the HOE 33 during reproduction and reaches each position in the Y direction of the optical pupil P during reproduction. . Since the size of the optical pupil P in the Y direction (vertical direction) is 3 mm as described above, here, Y = −1.5 (mm corresponding to the pupil lower end, the pupil center, and the pupil upper end, respectively. ), Y = 0 (mm), and the diffraction peak wavelength of the image light reaching each position of Y = 1.5 (mm). In the Y direction, the direction in which the diffraction angle of the HOE 33 decreases, that is, the direction from the lower end of the pupil to the upper end of the pupil is positive.

From Table 2, the diffraction of the image light reaching the position (Y = 1.5) shifted from the center of the optical pupil P to the Y-direction positive side with respect to the diffraction peak wavelength of the image light reaching the center of the optical pupil P. The peak wavelength shifts to the long wavelength side, and the diffraction peak wavelength of the image light reaching the position (Y = −1.5) shifted from the center of the optical pupil P to the Y direction negative side shifts to the short wavelength side. I understand that. From this, the Y direction can be paraphrased as a direction in which the diffraction peak wavelength shifts in the plane of the optical pupil P, and the positive direction in the Y direction is a long diffraction peak wavelength in the Y direction. In other words, the direction is shifted to the wavelength side.

(About the setting of the emitted light intensity of the light source)
Next, the setting of the emitted light intensity of the light source 11 which is a feature of the present invention will be described. FIG. 1 shows spectral characteristics (radiated light intensity characteristics) of the light source 11 (for example, the configuration of FIG. 4). As shown in the figure, the light source 11 has an intensity peak of radiated light in each of the RGB wavelength ranges. In the figure, relative intensity characteristics when the maximum radiated light intensity of B is set to 1 are shown.

Here, in each of the RGB wavelength ranges, the radiated light intensity of the light source 11 with respect to the diffraction peak wavelength of the image light incident on the Y-direction positive end of the optical pupil P is respectively expressed as E _RY , E _GY , E _BY. and then, the emitted light intensity of the light source 11 for the diffraction peak wavelength of the image light to be incident on the end portion of the negative side in the Y direction of the optical pupil, respectively _{E R-Y, E G-} Y, and _{E B-Y,} optical Assume that the radiated light intensities of the light source 11 with respect to the diffraction peak wavelength of the image light incident on the center of the pupil P are E _R0 , E _G0 and E _B0 , respectively. Table 3 shows the values of the parameters related to the light source 11 of the present embodiment.

As shown in Table 3, in this embodiment, the following conditional expressions (4) and (5) are satisfied. That is,
_{E BY -E BY <0 ··· (} 4)
_{E RY -E RY> 0 ··· (} 5)
It is.

When the conditional expressions (1), (2), and (3) described above are satisfied, that is, the point light source 81 arranged on the optical pupil P side at the time of manufacturing the HOE 33 is arranged on the surface of the substantially optical pupil P. As described above, when the HOE 33 is manufactured, when the observer's pupil is shifted from the center of the optical pupil P, the diffraction peak wavelength of the image light incident on the observer's pupil is shifted.

On the other hand, the light intensity (observation illuminance) that the observer feels when observing an image is determined by the image light intensity and the relative visibility. The former image light intensity is substantially determined by the product of the radiated light intensity of the light source 11 and the diffraction efficiency of the HOE 33. On the other hand, as shown in FIG. 17, the specific luminous sensitivity of the latter is the highest in the vicinity of the wavelength 555 nm, and decreases from the wavelength toward the long wavelength side and the short wavelength side. That is, the relative visibility is higher in the B wavelength region as it is longer, and is lower in the R wavelength region as it is longer.

When the conditional expressions (4) and (5) are satisfied, the change in the emitted light intensity of the light source 11 in the B and R wavelength ranges is opposite to the change in the relative luminous sensitivity. That is, the emitted light intensity of the light source 11 is low on the long wavelength side in the B wavelength range and high on the long wavelength side in the R wavelength range. As a result, even if the observer's pupil deviates from the center of the optical pupil P in either the positive or negative direction in the Y direction, the change in the RGB observation illuminance ratio due to the difference in the pupil position in the Y direction is reduced in consideration of the relative visibility. Can be suppressed. As a result, it is possible to suppress a change in the color of the video perceived by the observer depending on the pupil position in the Y direction.

FIG. 8 shows the change in the RGB observation illuminance ratio due to the difference in the pupil position in the Y direction in the present embodiment, with the G observation illuminance as a reference. From the figure, it can be seen that, compared to the conventional example shown in FIG. 26, the change in the RGB observation illuminance ratio is suppressed to be small, particularly at the pupil end portion (upper pupil end, lower pupil end) in the Y direction.

In other words, by satisfying the conditional expressions (4) and (5), the positive and negative slopes of the straight line connecting the two points on the radiated light intensity curve and the two points on the relative luminous efficiency curve are obtained in the B and R wavelength regions. The polarity of the connecting straight line is reversed, and this relationship works in a direction to suppress the change in the RGB observation illumination ratio due to the difference in the pupil position in the Y direction, so that the color of the image perceived by the observer is in the Y direction. It is possible to suppress the change depending on the pupil position.

Note that although the diffraction efficiency of the HOE also affects the observation illuminance, the maximum diffraction efficiency of the HOE for the light reaching each pupil position is substantially constant as described above, so that the conditional expressions (4) and (5) are satisfied. By doing so, the change in RGB observation illuminance ratio can be reduced at any pupil position in the Y direction, and the change in the color of the observation image due to the pupil position can be reduced.

Further, from Table 3, it can be seen that the following conditional expressions (6) and (7) are further satisfied in this embodiment. That is,
_{(E BY -E B0) × (} E B0 -E BY)> 0 ··· (6)
_{(E RY -E R0) × (} E R0 -E RY)> 0 ··· (7)
It is.

Condition mentioned above (4), _i.e., is satisfied under the conditions that satisfy the E _{BY -E BY} <0, the conditional expression _(6), between _{E BY,} E _B0, E _{BY the,} it holds the relationship of _{E BY <E B0 <E BY} . This means that in the wavelength range of B, the emitted light intensity becomes lower (monotonically decreasing) toward the longer wavelength side. Further, the above-mentioned conditional expression (5), _i.e., it is satisfied under the conditions that satisfy the E _{RY -E RY>} 0, the conditional expression _{(7), E RY, E} R0, E RY _between, holds the relationship of _{E RY> E R0> E RY} . This means that in the wavelength region of R, the emitted light intensity becomes higher as the wavelength is longer (monotonically increasing).

On the other hand, as shown in FIG. 17, the specific visibility becomes higher in the B wavelength region on the shorter wavelength side than the wavelength 555 nm (monotonically increases), and on the longer wavelength side than the wavelength 555 nm. In the wavelength region of R, the longer the wavelength, the lower (monotonically decreasing).

In the present embodiment, in the B wavelength range, the change in the radiated light intensity of the light source 11 is a monotonous change in accordance with the monotonous change in the relative luminous efficiency, and is opposite to the change in the monochromatic sensitivity (monotonic increase). On the other hand, in the wavelength region of R, the change in the intensity of the radiated light of the light source 11 is changed to a monotonous change in accordance with the monotonous change in the relative luminous efficiency, and is opposite to the change in the luminous efficiency (monotonic decrease). The monotonic increase. In other words, in the B and R wavelength regions, the radiated light intensity characteristics are adapted to the monotonous change in specific visibility. Thereby, the effect of this invention which suppresses the change of the color of the observation image | video by the difference in the pupil position of a Y direction can be heightened.

[Embodiment 2]
The following will describe still another embodiment of the present invention 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.

The video display device 1 of the present embodiment has the same configuration as that of the first embodiment except that the diffraction characteristics of the HOE 33 and the emitted light intensity characteristics of the light source 11 are different.

FIG. 9 is an explanatory view showing, in an enlarged manner, main parts of the manufacturing optical system of the HOE 33 applied to the video display device 1 of the present embodiment. The HOE 33 of this embodiment is manufactured as follows. That is, among the point light sources 81R, 81G, and 81B arranged on the optical pupil P side at the time of exposure, the point light sources 81G and 81B are arranged at the center of the optical pupil P, while the point light source 81R is arranged with respect to the point light sources 81G and 81B. The HOE 33 is manufactured by shifting the optical pupil P on the surface and exposing the hologram photosensitive material 33a in this state. At this time, the incident angle of the R exposure light beam from the point light source 81R to the hologram photosensitive material 33a is 30 degrees, and the incident angle of the B and G exposure light beams from the point light sources 81B and 81G to the hologram photosensitive material 33a is It is 32 degrees.

In this embodiment, the diffraction peak wavelength of the HOE 33 for light passing through the center of the optical pupil P during reproduction is as shown in Table 4.

In the present embodiment, the RGB exposure wavelengths are, for example, 647 nm, 532 nm, and 476.5 nm, and the shrinkage rate in the thickness direction of the hologram photosensitive material 33a is, for example, 2%. On the other hand, the used wavelengths of RGB (wavelengths reaching the pupil center when the used wavelength region of the light source 11 is taken into consideration) are, for example, 627.4 nm, 526.9 nm, and 471.9 nm. In other words, the difference between the exposure wavelength and the use wavelength is larger in R than in G or B.

Therefore, in consideration of the deviation between the exposure wavelength and the used wavelength for R as described above, the point light source 81R is arranged away from the point light sources 81G and 81B, and the HOE 33 is manufactured, so that the optical signal can be obtained during image observation. When the observer's pupil center is made to coincide with the center of the pupil P, the illumination light is reliably diffracted and reflected by the HOE 33 at all angles of view and reaches the observer's pupil. Therefore, the observer can observe a bright and high-definition image over the entire screen at the center position of the optical pupil P.

Table 5 shows diffraction peak wavelengths of image light that is diffracted and reflected by the HOE 33 at the time of reproduction and reaches each position in the Y direction of the optical pupil P using the HOE 33 produced by the above-described manufacturing optical system. Note that the size of the optical pupil P in the Y direction (vertical direction) is 3 mm, as in the first embodiment, and here, corresponding to the pupil lower end, the pupil center, and the pupil upper end, respectively, Y = −1. The diffraction peak wavelength of the image light reaching each position of 5 (mm), Y = 0 (mm), and Y = 1.5 (mm) is shown.

From Table 5, also in this embodiment, with respect to the diffraction peak wavelength of the image light reaching the center of the optical pupil P, the position is shifted to the Y-direction positive side from the center of the optical pupil P (Y = 1.5). The diffraction peak wavelength of the image light that arrives shifts to the long wavelength side, and the diffraction peak wavelength of the image light that reaches the position shifted from the center of the optical pupil P to the Y direction negative side (Y = −1.5) is It turns out that it has shifted to the short wavelength side.

Next, the radiated light intensity characteristic of the light source 11 of this embodiment will be described. FIG. 10 shows the radiated light intensity characteristics of the light source 11 of the present embodiment. In this embodiment, the light source 11 is composed of an RGB-integrated white LED (3-chip in 1 package) in which chips emitting RGB individual light are packaged, and the RGB emitted light intensity is independent. Thus, the configuration can be controlled. Here, Table 6 shows the value of each parameter related to the light source 11 of the present embodiment.

From Table 6, in this embodiment, in addition to satisfying all of the conditional expressions (1) to (5) shown in the first embodiment, the following conditional expression (8) is further satisfied: I understand. That is,
_{E RY / E RY> E BY} / E BY ··· (8)
It is.

When satisfying the conditional expression _(8), the ratio of _{E RY} for _{E RY is} is greater than the ratio of _{E BY} for _{E BY,} towards the wavelength range of R than the wavelength region of B is, the light source 11 The change in the intensity of the emitted light increases. In general, the change in the relative visibility is larger in the R wavelength region than in the B wavelength region. Therefore, by setting the radiated light intensity of the light source 11 as described above, the change in R due to the difference in the pupil position in the Y direction is set. The change in observation illuminance can be effectively reduced. Therefore, the balance of the observation illuminance between B and R due to the difference in the pupil position in the Y direction (change in the observation illuminance ratio between B and R) can be reduced, and the color of the image felt by the observer is the pupil in the Y direction. The change depending on the position can be further reduced.

FIG. 11 shows the change in the RGB observation illuminance ratio due to the difference in the pupil position in the Y direction in the present embodiment, with the G observation illuminance as a reference. From the figure, it can be seen that the change in the observation illuminance ratio of R and B due to the difference in the pupil position in the Y direction is suppressed to be smaller than that in the first embodiment.

In the present embodiment, it is desirable that the following conditional expression (9) is further satisfied. That is,
_{(E RY / E RY) /} (E BY / E BY) <2 ··· (9)
It is.

By satisfying conditional expression (9), the change in the radiated light intensity of the light source 11 in the R wavelength range is set to an appropriate range with respect to the change in the radiated light intensity of the light source 11 in the B wavelength range. Therefore, since the change in the intensity of the emitted light does not become too large, it is possible to reliably suppress the change in the color of the image perceived by the observer depending on the pupil position in the Y direction.

In this embodiment, it is desirable that the following conditional expression (10) is further satisfied. That is,
_{E GY -E GY <0 ··· (} 10)
It is.

In order to realize a wide color reproduction range in a chromaticity diagram (for example, a diagram represented by XY chromaticity coordinates in the XYZ color system), it is desirable that the peak wavelength of the G image light is between 500 nm and 540 nm. The relative visibility in the above wavelength range becomes higher on the longer wavelength side (monotonically increasing) as in the B wavelength range.

Therefore, by satisfying the conditional expression (10), the radiated light intensity of the light source 11 is low on the long wavelength side in the G wavelength range, similarly to the B wavelength range, so that G due to the difference in the pupil position in the Y direction. The change in observation illuminance can be kept small. As a result, it is possible to suppress a change in the color of the image perceived by the observer depending on the pupil position in the Y direction while widening the color reproduction region of the observation image.

In the present embodiment, it is desirable that the following conditional expression (11) is further satisfied. That is,
_{E RY / E RY> E GY} / E GY ··· (11)
It is.

When satisfying the conditional expression _(11), the ratio of _{E RY} for _{E RY is} is greater than the ratio of _{E GY} for _{E GY,} towards the wavelength range of R than the wavelength band of G is, the light source 11 The change in the intensity of the emitted light increases. Since the change in the relative visibility is generally larger in the R wavelength range than in the G wavelength range, setting the radiated light intensity of the light source 11 as described above makes it possible to change the R value due to the difference in the pupil position in the Y direction. While effectively suppressing the change in the observation illuminance, it is possible to reduce the balance of the observation illuminance between G and R (change in the illuminance ratio between G and R) due to the difference in the pupil position in the Y direction.

In the present embodiment, it is desirable that the following conditional expression (12) is further satisfied. That is,
_{(E RY / E RY) /} (E GY / E GY) <4 ··· (12)
It is.

By satisfying conditional expression (12), the change in the radiated light intensity of the light source 11 in the R wavelength range is set to an appropriate range with respect to the change in the radiated light intensity of the light source 11 in the G wavelength range. Therefore, the change in the color of the observation image due to the difference in the pupil position in the Y direction can be reliably suppressed.

In the present embodiment, it is desirable that the following conditional expression (13) is further satisfied. That is,
_{(E GY -E G0) × (} E G0 -E GY)> 0 ··· (13)
It is.

Above conditional expression (10), _i.e., is satisfied under the conditions that satisfy the E _{GY -E GY} <0, the conditional expression _(13), between _{E GY,} E _G0, E _{GY the,} it holds the relationship of _{E GY <E G0 <E GY} . This means that in the G wavelength range, the emitted light intensity becomes lower (monotonically decreasing) toward the longer wavelength side. On the other hand, the relative visibility is generally higher in the G wavelength region shorter than the wavelength 555 nm as the longer wavelength side (monotonically increases).

By satisfying conditional expression (13), as in the B wavelength range, the change in the emitted light intensity of the light source 11 in the G wavelength range is changed to a monotonous change in accordance with the monotonous change in the relative luminous efficiency. It is a monotonic decrease opposite to the change in monoscopic sensitivity (monotonic increase), and the radiated light intensity characteristic is adapted to the monotonous change in specific visibility in the G wavelength range. Thereby, the effect of this invention which suppresses the change of the color of the observation image | video by the difference in the pupil position of a Y direction can further be heightened.

Table 6 shows that in this embodiment, all conditional expressions (9) to (13) are satisfied.

[Embodiment 3]
The following will describe still another embodiment of the present invention with reference to the drawings. For convenience of explanation, the same components as those in Embodiments 1 and 2 are denoted by the same member numbers, and the description thereof is omitted.

FIG. 12 is a cross-sectional view showing a schematic configuration of the video display device 1 of the present embodiment and the HUD including the same. The video display device 1 according to the present embodiment includes a light source 11, an illumination lens 22 as the illumination optical system 12, a display element 13, and an observation optical system 15.

The observation optical system 15 includes a volume phase type reflection type HOE 34 and a substrate 35 that holds the HOE 34. The substrate 35 can be composed of a transparent windshield corresponding to the windshield in front of the driver's seat in a vehicle, ship, railroad, aircraft, etc., for example, at least a part of which is within the observer's field of view. Placed in.

According to the above configuration, the light emitted from the light source 11 is collected by the illumination lens 22 and enters the display element 13. Light (video light) modulated in accordance with image data by the display element 13 enters the HOE 34, where it is diffracted and reflected and guided to the optical pupil P. At the position of the optical pupil P, the observer can observe the magnified virtual image of the image displayed on the display element 13 and can observe the outside world through the HOE 34 and the windshield 35.

It should be noted that the HUD may be configured by holding the HOE 34 on a substrate separate from the windshield and placing the substrate in the field of view of the observer. In this case, the HUD can function as a document display device such as a prompter. Therefore, it can be said that the HUD of the present embodiment only needs to be configured by holding the HOE 34 of the video display device 1 on the substrate disposed in the field of view of the observer.

By the way, HUD, like HMD, is a see-through display that can be observed with images superimposed on the background (outside). In the HUD, the above-described HOE 34 is used as a combiner that superimposes image light and external light. However, since the HOE 34 is often arranged substantially parallel to the substrate 35, it is necessary to consider the surface reflection of the substrate 35. is there. That is, when the optical system is set so that the light beam at the center of the screen is substantially regularly reflected by the HOE 34, the angle deviation between the light diffracted by the HOE 34 and the light reflected by the surface of the substrate 35 is small. The image due to the surface reflection is observed as a ghost.

In order to avoid the observation of such a ghost image, it is necessary to set the diffraction angle at the HOE 34 to deviate from the regular reflection angle with respect to all image heights. In this embodiment, the angle at which the screen center chief ray (ray on the optical axis) from the display element 13 enters the HOE 34 is 45.5 °, and the exit angle after the screen center chief ray is diffracted by the HOE 34 is 35. By setting the viewing angle in the vertical direction to 5.4 ° and the viewing angle in the horizontal direction to 7.2 °, the light reflected by the surface of the substrate 35 is reflected outside the observation region. In the present embodiment, the size of the optical pupil P is about 50 mm in diameter.

FIG. 13 is an explanatory view showing, in an enlarged manner, main parts of the manufacturing optical system of the HOE 34. As shown in FIG. In the manufacturing optical system, the light source 91 is disposed on the surface of the optical pupil P (for example, the center of the pupil). The light beam emitted from the light source 91 is irradiated to the hologram photosensitive material 34a as it is (from the side opposite to the substrate 35). On the other hand, a light source 92 and a wavefront generating optical system 93 are disposed on the opposite side (substrate 35 side) of the hologram photosensitive material 34a from the optical pupil P, and the light beam emitted from the light source 92 is wavefront generating optical. After being converted into a light beam having a desired wavefront by the system 93, the hologram photosensitive material 34a is irradiated. By recording these two light flux interference fringes on the hologram photosensitive material 34a as a refractive index distribution, the HOE 34 is manufactured. Note that light emitted from an RGB laser light source (not shown) is focused on one point at the positions of the light sources 91 and 92.

In this embodiment, the diffraction peak wavelength of the HOE 34 for the light passing through the center of the optical pupil P during reproduction is as shown in Table 7.

Table 8 shows diffraction peak wavelengths of image light that is diffracted and reflected by the HOE 34 at the time of reproduction and reaches each position in the Y direction of the optical pupil P at the time of reproduction using the HOE 34 manufactured by the above-described manufacturing optical system. . In the present embodiment, the direction in which the diffraction angle of the HOE 33 decreases in the plane of the optical pupil P in FIG. 12 is the direction from the upper end of the pupil to the lower end of the pupil, and therefore, this direction is defined as the positive direction of the Y direction. Yes. In the present embodiment, since the size of the optical pupil P in the Y direction (vertical direction) is 50 mm as described above, in Table 8, corresponding to the pupil upper end, the pupil center, and the pupil lower end, Y = −25 The diffraction peak wavelengths of the image light reaching the respective positions (mm), Y = 0 (mm), and Y = 25 (mm) are shown.

From Table 8, with respect to the diffraction peak wavelength of the image light reaching the center of the optical pupil P, the diffraction peak wavelength of the image light reaching the position shifted from the center of the optical pupil P to the Y direction positive side (Y = 25). Is shifted to the long wavelength side, and the diffraction peak wavelength of the image light reaching the position (Y = −25) shifted from the center of the optical pupil P to the Y direction negative side is shifted to the short wavelength side. Therefore, the Y direction is the direction in which the diffraction peak wavelength shifts in the plane of the optical pupil P, and the positive direction in the Y direction is the direction in which the diffraction peak wavelength shifts to the long wavelength side in the Y direction. It can be said that a certain point is the same as in the first and second embodiments.

Next, the radiated light intensity characteristic of the light source 11 of this embodiment will be described. FIG. 14 shows the radiated light intensity characteristics of the light source 11 of the present embodiment. In the present embodiment, as in the second embodiment, the light source 11 is configured by an RGB-integrated white LED (3-chip in one package) in which chips emitting RGB individual light are packaged in one package. The RGB radiation light intensity can be controlled independently. Here, Table 9 shows the value of each parameter related to the light source 11 of the present embodiment.

From Table 9, in this embodiment, in addition to satisfying all the conditional expressions (1) to (5) shown in the first embodiment, the conditional expressions (8) to (8) shown in the second embodiment are satisfied. It can be seen that 12) is further satisfied.

FIG. 15 shows the change in the RGB observation illuminance ratio due to the difference in the pupil position in the Y direction in this embodiment with reference to the G observation illuminance. From the figure, it can be seen that the change in the RGB observation illuminance ratio due to the difference in the pupil position in the Y direction is significantly improved as compared with the conventional case shown in FIG.

[Supplement]
When exposing the hologram photosensitive material with the light source position on the optical pupil side at the time of exposure away from the optical pupil (the limit value of the distance between the optical pupil and the light source is infinite), and using the produced HOE, Color unevenness due to pupil position shift does not occur, but color unevenness occurs in the screen. However, even in this case, as in the present invention, if the radiated light intensity characteristic of the light source is reversed from the relative visibility characteristic, that is, in the wavelength range of RGB image light incident on the optical pupil, If the slope of the straight line connecting the two points is reversed to the slope of the straight line connecting the two points on the relative visibility curve, the color balance shift due to the pupil position can be reduced. It is also possible to improve color balance deviation by performing color correction (image data correction) within the image screen.

The wavelength region of RGB image light incident on the optical pupil includes color reproduction out of the wavelength region determined by the combination of the wavelength of the laser light source available for exposure and the light source satisfying the above-described conditional expression of the present invention. It is desirable to select a wide wavelength region. For example, if the intensity peak wavelength of RGB image light incident on the optical pupil is in the range of B: 450 nm to 480 nm, G: 510 nm to 540 nm, and R: 610 nm to 650 nm, the RGB color purity in the observed image is increased. Thus, the color reproduction area can be expanded.

Of course, the video display device, the HMD, and the HUD can be configured by appropriately combining the configurations described in the embodiments. In addition, by appropriately setting the emitted light intensity of the light source, the image display satisfying the above-described conditional expressions (1) to (5) and satisfying at least one of the conditional expressions (6) to (13). An apparatus can be realized.

The video display device of the present invention can be used for HMD and HUD, for example.

DESCRIPTION OF SYMBOLS 1 Image display apparatus 2 Support means 11 Light source 11a Area | region 13 Display element 14 Eyepiece optical system (observation optical system)
15 Observation optical system 33 HOE
34 HOE
35 Substrate P Optical pupil

Claims (12)

1. A light source;
   A display element that displays light by modulating light from the light source;
   An observation optical system having a volume phase type reflection type hologram optical element that diffracts and reflects the image light from the display element and guides it to the optical pupil, and an image display device comprising:
   The light source has an intensity peak of radiated light in each wavelength region of red, green, and blue,
   In each of the red, green, and blue wavelength ranges, the longest wavelength among the diffraction peak wavelengths of image light that enters the center of the optical pupil from each position on the display surface of the display element via the hologram optical element Are λRlong, λGlong, and λBlong respectively, and those on the shortest wavelength side are respectively λRshort, λGshort, and λBshort,
   λRlong / λRshort <1.05
   λGlong / λGshort <1.05
   λBlong / λBshort <1.05
   Satisfied,
   The direction in which the diffraction peak wavelength shifts in the plane of the optical pupil is the Y direction, the direction in which the diffraction peak wavelength shifts to the long wavelength side in the Y direction is positive, and the Y of the optical pupil is in each of the red and blue wavelength regions. direction of the positive side of the radiation intensity of the light source for the diffraction peak wavelength of the image light to be incident on the end portion respectively E _RY, and E _bY, the image light incident on the end portion of the negative side in the Y direction of the optical pupil the emitted light intensity of the light source for the diffraction peak wavelengths E _R-Y, when the _{E B-Y,}
   E _BY -E _BY <0
   E _RY -E _RY> 0
   An image display device characterized by satisfying
2. _{E RY / E RY> E BY} / E BY
   The video display device according to claim 1, wherein:
3. _{(E RY / E RY) /} (E BY / E BY) <2
   The video display device according to claim 2, wherein:
4. In each of the red and blue wavelength regions, if the radiated light intensity of the light source for the diffraction peak wavelength of the image light incident on the center of the optical pupil is E _R0 and E _B0 , respectively,
   _{(E BY -E B0) × (} E B0 -E BY)> 0
   _{(E RY -E R0) × (} E R0 -E RY)> 0
   4. The video display device according to claim 1, wherein:
5. In the green wavelength range, the radiated light intensity of the light source for the diffraction peak wavelength of the image light incident on the Y-direction positive end of the optical pupil is E _GY, and the negative end of the optical pupil in the Y-direction when the emitted light intensity of the light source for the diffraction peak wavelength of the image light incident was E _G-Y, the
   E _GY -E _GY <0
   5. The video display device according to claim 1, wherein:
6. _{E RY / E RY> E GY} / E GY
   The video display device according to claim 5, wherein:
7. _{(E RY / E RY) /} (E GY / E GY) <4
   The video display device according to claim 6, wherein:
8. When the emitted light intensity of the light source for the diffraction peak wavelength of the image light incident on the center of the optical pupil in the green wavelength region is E _G0 ,
   _{(E GY -E G0) × (} E G0 -E GY)> 0
   The video display device according to claim 5, wherein:
9. The image display device according to any one of claims 1 to 8, wherein the light source and the optical pupil are conjugate.
10. 10. The video display device according to claim 1, wherein light in each wavelength region of red, green, and blue is emitted from the same region in the light source.
11. A video display device according to any one of claims 1 to 10,
    And a support means for supporting the video display device in front of the observer's eyes.
12. A head-up comprising the video display device according to claim 1, wherein the hologram optical element of the video display device is held on a substrate disposed in a field of view of an observer. display.

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