JP2008287049A - Image display apparatus and head-mounted display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display apparatus which allows an observer with different pupil distances to observe bright high-definition images with a simple constitution free from a pupil distance adjustment mechanism. <P>SOLUTION: When both right and left LCDs are made into a display state of white solid color images, observation pupils E<SB>R</SB>, E<SB>L</SB>have color distributions in the pupils with different image colors in accordance with the positions in the pupil distance directions. Then, when the right eye and left eye are located in the vicinities of the respective centers of the observation pupils E<SB>R</SB>, E<SB>L</SB>, the observation images R, L have the same color, and, when the right eye and left eye are located in the positions separated by equal distances from the respective centers of the observation pupils E<SB>R</SB>, E<SB>L</SB>to between the insides or between outsides in the pupil distance directions, respectively, the observation images R, L have different colors each other. In this way, images with colors different in the right eye and left eye are made to observe by each observer with different pupil distances, so that the satisfactory images having reduced color unevenness can be observed by both eyes observation. Thus, an effort of reducing color unevenness in individual pupils is reduced, and also, there is no need of increasing the diffusion degree of a diffusion board. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention comprises a video display unit R for the right eye and a video display unit L for the left eye, displays a video on each unit, and allows an observer to observe them with both eyes, The present invention relates to a head mounted display (hereinafter also referred to as HMD) provided with the video display device.

  In the HMD, in order to allow an observer with different eye widths to observe each display image of the image display element provided corresponding to both eyes, for example, as in Patent Document 1, an eye width adjustment mechanism is provided. There is a way. This eye width adjustment mechanism moves the left and right eyepieces separately in the direction approaching or separating from the nose pad so as to match the positions of the left and right eyes.

  However, the configuration in which the eye width adjustment mechanism is provided causes an increase in size and weight of the device, which is a factor that hinders the realization of a compact and lightweight video display device or HMD. In addition, since it is necessary to adjust the positions of the left and right eyepieces for each observer to be used, the usability is not very good.

  Therefore, there is also a technique for allowing observers with different eye widths to observe images well by enlarging the observation pupil in the eye width direction without providing an eye width adjusting mechanism. In general, the pupil can be enlarged in the lateral direction by largely diffusing the illumination light in the eye width direction using the diffusing means. For example, in Patent Document 2, the eye width is determined by diffraction by the diffractive optical element. By making a plurality of observation pupils in the direction, the pupil is expanded in the horizontal direction.

JP-A-5-276467 Japanese Patent No. 3623265

  However, if the diffusivity of the diffusing means is increased in order to widen the observation pupil in the eye width direction, the utilization efficiency of the light emitted from the light source is deteriorated, and the observed image becomes dark. In particular, when an observer observes a color image using an illumination light source having a plurality of wavelengths, color unevenness occurs in the observed image due to a difference in the position of the light emitting unit of the plurality of wavelengths, but such color unevenness is eliminated. In order to do so, it is necessary to diffuse all the light of each color to the same extent, and there is a concern that the observed image will become darker. On the other hand, if the diffusivity of the diffusing means is lowered, a bright image can be obtained, but the above color unevenness cannot be reduced. Further, in the method of Patent Document 2 in which a plurality of observation pupils are formed in the eye width direction, an image at each pupil becomes dark.

  That is, with the method of widening the observation pupil in the eye width direction, the observed image becomes dark and it is impossible to observe a high-quality image with reduced color unevenness for each observer with different eye widths.

  The present invention has been made in order to solve the above-described problems, and its object is to provide a simple structure without an eye width adjustment mechanism, which is bright and high in image quality for observers having different eye widths. An object of the present invention is to provide an image display device capable of observing an image and an HMD equipped with the image display device.

  The video display device of the present invention is a video display device including a video display unit R for the right eye and a video display unit L for the left eye. The video display unit R includes a light source R and a light source R. Image display element R for displaying an image by transmitting or reflecting the light of each pixel for each pixel, and an eyepiece optical system R for guiding the image light from the image display element R to the observation pupil R, and an image display unit L denotes a light source L, a video display element L that displays video by transmitting or reflecting light from the light source L for each pixel, and an eyepiece optical system that guides video light from the video display element L to the observation pupil L. L, and when the images observed by the right eye and the left eye are respectively an observation image R and an observation image L, all the pixels of both the image display element R and the image display element L are in a light transmission state or light. When in the reflective state, The pupil R and the observation pupil L have intra-pupil color distributions in which the image colors differ depending on the position in the eye width direction, and the right eye and the left eye are located in the vicinity of the centers of the observation pupil R and the observation pupil L. The observation image R and the observation image L at the same time are the same color, and the right eye and the left eye are located at positions equidistant from the centers of the observation pupil R and the observation pupil L to the inner side or the outer side, respectively. In this case, the observation image R and the observation image L have different colors.

  According to the above configuration, in the video display unit R, the light from the light source R is modulated for each pixel by the video display element R, and is emitted from there as video light, and through the eyepiece optical system R, the observation pupil R Led to. Similarly, in the video display unit L, light from the light source L is modulated for each pixel by the video display element L, is emitted therefrom as video light, and is guided to the observation pupil L through the eyepiece optical system L. Thus, if the observer's right eye and left eye are respectively positioned on the observation pupils R and L, the observer can view the virtual image of the video displayed on the video display elements R and L with both the right eye and the left eye. It becomes possible to observe.

  In addition, when all the pixels of both the image display elements R and the image display elements L are set to the light transmitting state or the light reflecting state, the observation pupils R and L each have an intra-pupil color distribution (in-pupil color unevenness). The observation images R and L when the right eye and the left eye are located in the vicinity of the centers of the observation pupils R and L are the same color, and the inner sides or the outer sides of the observation pupils R and L, respectively, The observation images R and L when the right eye and the left eye are located at positions equidistant from each other have different colors. As a result, the direction of change of the intra-pupil color distribution can be made the same on the left and right, that is, the way of changing the colors of the images in the observation pupils R and L can be made the same, and the design interpupillary distance (design) It is possible for an observer with different eye width distances to observe images of different colors on the left and right. For example, when the colors of the images in the observation pupils R and L change from left to right such as “bluish white”, “white”, and “reddish white”, the distance between the eyes The observer who has a small image will observe the “reddish white” image as the observed image L with the left eye and the “bluish white” image as the observed image R with the right eye.

  In this way, by allowing an observer with an eye distance different from the designed eye distance to observe images of different colors on the left and right with both eyes, the left and right images are added together, and the observation pupils R · L An image close to the color of the image at the center (“white” in the above example) can be observed. As a result, even if color unevenness is large in each of the observation pupils R and L, an observer with an eye width distance that is different from the designed eye width distance looks as if the image display device has a small color unevenness. The image can be observed well. Therefore, efforts to reduce color unevenness in individual pupils are reduced.

  In order to reduce color unevenness in individual pupils, for example, there is a method of increasing the diffusivity using a diffusing plate. However, in the present invention, it is not necessary to use a diffusing plate having a high diffusivity. In addition, since images of different colors are observed on the left and right by an observer having an eye width different from the designed eye width distance, a conventional eye width adjustment mechanism is provided, or the observation pupils R and L are each provided with a plurality of pupils. It is no longer necessary to expand the eye width direction. As a result, according to the present invention, a bright image with high image quality can be observed by an observer having a different eye width distance from the designed eye width distance with a simple configuration without an eye width adjusting mechanism.

  In the video display device of the present invention, when all the pixels of both the video display element R and the video display element L are in the light transmission state or the light reflection state, the center of the observation pupil R and the observation pupil L is measured. The observation image R and the observation image L can be added together rather than the observation image R and the observation image L when the right eye and the left eye are located at positions equidistant from each other inside the eye width direction or outside each other. It is desirable that the observation image B is closer to the color of the image at each center of the observation pupil R and the observation pupil L.

  In this case, at the time of binocular observation, the observer can visually recognize an image closer to the color of the image at the center of the observation pupil R and the observation pupil L than the color of the image observed at the time of one-eye observation.

  Further, in the video display device of the present invention, when all the pixels of both the video display element R and the video display element L are in the light transmission state or the light reflection state, the intra-pupil colors in the observation pupil R and the observation pupil L When the distribution is expressed by XY chromaticity coordinates in the XYZ color system, at least the difference between the chromaticity X coordinate values and the difference between the chromaticity Y coordinate values at both ends in the eye width direction in each of the observation pupil R and the observation pupil L. One is preferably 0.05 or more.

  In this case, color unevenness in which the color of the image varies depending on the position in the eye width direction surely occurs in the observation pupils R and L. This makes it possible for an observer with an eye width distance different from the designed eye width distance to observe images of different colors with the left and right eyes, and as an observation image with both eyes, An image closer to the color of the image at the center of the observation pupil R / L can be observed than the observed image.

  In the video display device of the present invention, when all the pixels of both the video display element R and the video display element L are in the light transmission state or the light reflection state, the observation image R and the observation image L are within the observation screen. When the right eye and the left eye are located at any position in the observation pupil R and the observation pupil L, the observation image R and the observation image L are expressed as XY chromaticity coordinates in the XYZ color system. It is desirable that both the chromaticity X coordinate value and the chromaticity Y coordinate value of the color distribution can be 0.03 or less.

  In this case, even if the right eye and the left eye are located at any position in the observation pupils R and L, the observation images R and L have no color unevenness of a level that can be recognized as a difference in color, and the observer can individually As the observed images R and L, it is possible to observe a good image without color unevenness.

  In the video display device according to the present invention, when all the pixels of both the video display element R and the video display element L are in the light transmission state or the light reflection state, the observation pupil R and the observation pupil L are the same as each other. It is desirable to line up in the eye width direction with intra-pupil color distribution.

  In this case, the observation images R and L when the right eye and the left eye are located in the vicinity of the centers of the observation pupils R and L have the same color, and the inner sides or the outer sides of the observation pupils R and L respectively The observation images R and L when the right eye and the left eye are located at positions equidistant from each other can have different colors. This allows an observer with an eye width distance different from the designed eye width distance to observe an image with different colors on the left and right with both eyes, and an image close to the color of the image at the center of the observation pupil R · L. Can be observed.

  In the video display device of the present invention, the light source R and the light source L are each composed of a plurality of light emitting units that emit light of different wavelengths. In the light source R and the light source L, each light emitting unit is an observer. The structure arrange | positioned along with the same order in the eye width direction may be sufficient.

  In this configuration, even when the image display elements R and L are driven in the same way (for example, when all the pixels of the image display elements R and L are in a light transmission state), the difference in position of each light emitting unit, It is possible to cause the same color unevenness in the observation pupils R and L due to a difference in intensity distribution of light emitted from the light emitting unit. This allows an observer with an eye width distance different from the designed eye width distance to observe an image with different colors on the left and right with both eyes, and an image close to the color of the image at the center of the observation pupil R · L. Can be observed.

  In the video display device of the present invention, the plurality of light emitting units may emit light having wavelengths corresponding to the three primary colors. In this case, a color image can be displayed on the image display elements R and L, and the observer can observe the color image during binocular observation.

  In the video display device of the present invention, in each of the video display unit R and the video display unit L, the light source and the observation pupil may be substantially conjugate in a direction perpendicular to the direction in which the light emitting units are arranged.

  In this case, in each of the left and right video display units R and L, light from the light source can be efficiently guided to the observation pupil in a direction perpendicular to the direction in which the light emitting units are arranged, and is bright at the position of the observation pupil. It is possible to make the observer observe the video.

  In the video display device of the present invention, in each of the video display unit R and the video display unit L, the eyepiece optical system includes a volume phase type reflection hologram optical element, and the video light from the video display element is received. A configuration in which the light is magnified and reflected by the hologram optical element and guided to the observer's eye as a virtual image, and the light of the external image transmitted through the hologram optical element may be guided to the observer's eye.

  In this case, since the image light from the image display element and the light of the external image are simultaneously guided to the observer's eyes by the hologram optical element (hereinafter also referred to as HOE), the see-through type can be observed with the image superimposed on the external image. The video display device is configured. At this time, since the HOE also serves as an eyepiece optical system, the apparatus can be reduced in size and weight. In addition, since the volume phase reflection type HOE has a narrow half-value wavelength width of diffraction efficiency, the light transmittance of the external image becomes high and the external image can be clearly observed.

In the video display device of the present invention, in each of the video display unit R and the video display unit L, the hologram optical element has a plurality of diffraction peak wavelengths at which the diffraction efficiency becomes a maximum value. On the other hand, the diffraction peak wavelength of the principal ray emitted from the center of the image display element and entering the center of the observation pupil is λ0, and the diffraction of the principal ray emitted from the periphery of the image display element and incident on the center of the observation pupil is performed. If the peak wavelength is λx,
0.98 ≦ (λx / λ0) ≦ 1.02
It is desirable that

  In this configuration, since the value of λx / λ0 is close to 1 and the difference between λx and λ0 is small, that is, the difference in diffraction peak wavelength between the center and the end of the viewing angle is small, the observer can observe The color unevenness in the images R and L can be observed very small.

  In the video display device of the present invention, in each of the video display unit R and the video display unit L, the eyepiece optical system includes a cemented optical member in which a hologram optical element is embedded, and the video light from the video display element May be made incident from the incident surface of the bonding optical member and totally reflected a plurality of times inside and guided to the hologram optical element.

  By adopting a configuration using total reflection inside the cemented optical member as described above, the cemented optical member can be reduced in size and weight. In addition, the image display element can be disposed around the visual field, and a wide external field viewing angle can be secured.

  In the video display device of the present invention, the hologram optical element may have a positive non-axisymmetric optical power for enlarging the video displayed on the video display element. In this case, the eyepiece optical system can be reduced in size, and an image with good aberration correction can be provided to the observer.

  In the video display device of the present invention, in each of the video display unit R and the video display unit L, it is desirable that the light source is composed of a light emitting diode. In this case, a bright image can be provided to the observer by matching the emission wavelength of the light source LED with the diffraction wavelength of the HOE.

  The video display device 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.

  According to the above configuration, since the video display device having the two video display units R and L is supported in front of the observer's eyes by the support means, the observer becomes hands-free, and the external image and the display on the video display element are displayed. While observing the image as a virtual image with both eyes, it is possible to perform a desired operation with a free hand. In addition, since the observation direction of the observer is determined in one direction, there is an advantage that the observer can easily search for a display image even in a dark environment.

  According to the present invention, by allowing observers with different eye widths to observe images of different colors on the left and right, high image quality can be achieved with a simple configuration that does not use a diffuser plate with high diffusivity or an eye width adjustment mechanism. A bright image can be observed by an observer.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to the drawings.
(1. About HMD)
2A is a plan view showing a schematic configuration of the HMD according to the present embodiment, FIG. 2B is a side view of the HMD, and FIG. 2C is a front view of the HMD. is there. The HMD has a video display device 1 and support means 2 for supporting it, and as a whole has an appearance like general glasses.

  The video display device 1 allows an observer to observe an external image through a see-through, displays an image, and provides the image as a virtual image to the observer. The video display unit 1R for the right eye and the left eye And a video display unit 1L. In the video display units 1R and 1L shown in FIG. 2C, portions corresponding to the right eye lens and the left eye lens of the glasses are bonded to an eyepiece prism 22 and a deflection prism 23 (both see FIG. 3) described later. It is constituted by. The detailed configuration of the video display units 1R and 1L will be described later.

  The support means 2 supports the video display units 1R and 1L in front of the right and left eyes of the observer, and includes a bridge 3, a frame 4, a temple 5, a nose pad 6, a cable 7, And an external light transmittance control means 8. The nose pad 6 and the external light transmittance control means 8 are supported by the bridge 3. The frame 4, the temple 5 and the nose pad 6 are provided as a pair on the left and right sides. However, when these are distinguished from each other, the right frame 4R, the left frame 4L, the right temple 5R, the left temple 5L, and the right nose pad 6R. The left nose pad 6L is expressed.

  The bridge 3 connects the video display units 1R and 1L. The right temple 5R is rotatably supported by the right frame 4R, and is connected to the video display unit 1R (on the side opposite to the connection side to the bridge 3) via the right frame 4R. Similarly, the left temple 5L is rotatably supported by the left frame 4L, and is connected to the video display unit 1L (on the side opposite to the connection side to the bridge 3) via the left frame 4L. .

  The cable 7 is a wiring for supplying external signals (for example, video signals and control signals) and power to the video display units 1R and 1L in parallel, and is provided along the right temple 5R, the right frame 4R, and the bridge 3. Yes. The external light transmittance control means 8 is provided to control the transmittance of external light (light of an external image), and is located in front of the video display devices 1R and 1L (on the side opposite to the observer). ing. The external light transmittance control means 8 may be provided as necessary.

  When the observer uses the HMD, the right temple 5R and the left temple 5L are brought into contact with the right and left heads of the observer, and the nose pad 6 is put on the nose of the observer so as to wear general glasses. The HMD is attached to the observer's head. In this state, when the video is displayed on the video display units 1R and 1L, the observer can observe each display video of the video display units 1R and 1L as a virtual image with the right eye and the left eye, respectively, and the video display unit 1R. -An external image can be observed with see-through through 1L.

  At this time, if the external light transmittance control unit 8 sets the external light transmittance to a low value of 50% or less, for example, the observer can easily observe the image on the image display units 1R and 1L. If the light transmittance is set to be high, for example, 50% or more, the observer can easily observe the external image. Therefore, the external light transmittance in the external light transmittance control means 8 may be set as appropriate in consideration of ease of observation of the video and external image of the video display units 1R and 1L.

(2. About the video display unit)
Next, details of the video display units 1R and 1L described above will be described. Since the basic configuration of the video display units 1R and 1L is the same, the configuration of the video display units 1R and 1L will be described below without distinguishing left and right. In particular, in the case of distinguishing between left and right, a symbol “R” indicating right or a symbol “L” indicating left is added (the same applies to the claims), and a member number is optionally added before the symbol. Shall be appended.

  FIG. 3 is a cross-sectional view showing a schematic configuration of the video display units 1R and 1L, and FIG. 4 is an explanatory diagram showing the optical path of light in the video display units 1R and 1L in an expanded manner. Each of the video display units 1R and 1L includes a video display unit 11 and an eyepiece optical system 21. The video display unit 11 includes a light source 12, a unidirectional diffuser plate 13, a condenser lens 14, and an LCD 15.

  The light source 12 is composed of an RGB-integrated LED that emits light in three wavelength bands with central wavelengths of, for example, 465 nm, 520 nm, and 635 nm, and is disposed near the object-side focal point of the condenser lens 14 described later. . Further, the RGB light emitting units of the light source 12 are arranged side by side in a horizontal direction (a direction perpendicular to the sheet of FIG. 3) corresponding to the eye width direction (left-right direction) when the observer wears the HMD, for example. ing. The details of the arrangement position of each light emitting unit will be described later.

  The unidirectional diffuser plate 13 diffuses illumination light from the light source 12, but the degree of diffusion differs depending on the direction. More specifically, the unidirectional diffuser plate 13 diffuses incident light by about 20 ° in the direction in which the RGB light-emitting portions of the light source 12 are arranged (the horizontal direction), and the direction perpendicular to the direction (HMD by the observer). Incident light is diffused by about 0.2 ° in the up-and-down direction (direction parallel to the paper surface of FIG. 3) when it is mounted. The condenser lens 14 is an illumination optical system that condenses the light diffused by the unidirectional diffusion plate 13. The condenser lens 14 is arranged so that the diffused light efficiently forms an observation pupil (optical pupil) E.

  The LCD 15 is a video display element that displays video by modulating light from the light source 12 for each pixel based on a video signal. In this embodiment, the LCD 15 is a transmissive type, but may be a reflective type. In this case, it is necessary to devise the arrangement position of other optical elements such as the light source 12. Further, a light modulation element other than the LCD (for example, DMD (Digital Micromirror Device; manufactured by Texas Instruments Incorporated, USA)) may be used as the image display element.

  On the other hand, the eyepiece optical system 21 includes a cemented prism (a cemented optical member), and configures a telecentric optical system. In this cemented prism, an eyepiece prism 22 and a deflecting prism 23 which are optical members are joined with an optical element 24 interposed therebetween.

  The eyepiece prism 22 and the deflection prism 23 are joined with an adhesive. The eyepiece prism 22 is formed in a shape in which the lower end portion of the parallel plate is wedge-shaped and the upper end portion is thickened, and has surfaces 22a, 22b, and 22c. The surface 22a is an incident surface on which image light from the image display unit 11 is incident, and the surfaces 22b and 22c are surfaces facing each other. Among these, the surface 22b is a total reflection surface and an emission surface.

  The deflection prism 23 is configured to be a substantially parallel flat plate integrally with the eyepiece prism 22 by forming the upper end portion of the parallel plate along the lower end portion of the eyepiece prism 22. When the deflecting prism 23 is not joined to the eyepiece prism 22, the light of the outside world image is refracted when passing through the wedge-shaped lower end of the eyepiece prism 22, so that the outside world image observed through the eyepiece prism 22 is distorted. However, the deflection prism 23 is joined to the eyepiece prism 22 to form an integral substantially parallel plate, so that the deflection when the light of the external image passes through the wedge-shaped lower end of the eyepiece prism 22 is canceled by the deflection prism 23. can do. As a result, it is possible to prevent distortion in the external image observed through the see-through.

  The eyepiece prism 22 and the deflection prism 23 are, for example, acrylic resins such as PMMA (polymethyl methacrylate) and MMA (methyl methacrylate), or cycloolefins such as ZEONEX (registered trademark) and Apel (registered trademark). It is made of resin. Since these organic materials have high transparency and low birefringence, good optical performance (for example, transmission characteristics) can be obtained by constituting the optical member with these materials.

  The adhesive used for joining the optical members is made of, for example, an acrylic or cycloolefin organic material that is the same series as the material of the optical member. This is because the same series of materials have high adhesion. In addition, these organic materials are “highly transparent”, “can be easily cured in a very short time by ultraviolet / visible light irradiation”, “because of the same series, the refractive index is similar to that of optical members, It has many advantages such as “the bonding line portion is less noticeable after bonding” and is extremely desirable as an adhesive used for bonding optical members. As such an adhesive, for example, LCR629B (manufactured by Toagosei Co., Ltd.), NOA76 (manufactured by Norland Products) or the like can be used.

  The optical element 24 may be configured by a half mirror, for example, but here, a volume phase that diffracts light in three wavelength bands, for example, 465 ± 10 nm, 520 ± 10 nm, and 635 ± 10 nm, which are incident at a specific incident angle. Type reflection hologram optical element (HOE). That is, this HOE has a plurality of diffraction peak wavelengths at which the diffraction efficiency becomes a maximum value. For each diffraction peak wavelength, the diffraction peak wavelength of the principal ray that is emitted from the center of the LCD 15 and incident on the center of the observation pupil E is λ0, and is emitted from the peripheral portion of the LCD 15 to the center of the observation pupil E. When the diffraction peak wavelength of the incident principal ray is λx, the HOE is manufactured so as to satisfy 0.98 ≦ (λx / λ0) ≦ 1.02. The optical element 24 made of such HOE is attached to the inclined surface at the lower end of the eyepiece prism 22, and as a result, is sandwiched between the eyepiece prism 22 and the deflection prism 23.

  With such a configuration of the video display units 1R and 1L, the light emitted from the light source 12 of the video display unit 11 is diffused by the unidirectional diffusion plate 13, condensed by the condenser lens 14, and incident on the LCD 15. To do. The light incident on the LCD 15 is modulated based on the video signal and emitted as video light. At this time, the image itself is displayed on the LCD 15.

  The image light from the LCD 15 enters the eyepiece prism 22 of the eyepiece optical system 21 from its upper end surface (surface 22a), is totally reflected a plurality of times by the two opposing surfaces 22b and 22c, and enters the optical element 24. To do. The light that has entered the optical element 24 is reflected there, exits through the surface 22b, and reaches the observation pupil E. At the position of the observation pupil E, the observer can observe an enlarged virtual image of the image displayed on the LCD 15. The distance from the observation pupil E to the virtual image is about several meters, and the size of the virtual image is 10 times or more that of the image displayed on the LCD 15.

  On the other hand, the eyepiece prism 22, the deflection prism 23, and the optical element 24 transmit almost all the light from the outside, so that the observer can observe the outside world image. Therefore, the virtual image of the image displayed on the LCD 15 is observed while overlapping with a part of the external image. From the above, it can be said that the optical element 24 functions as a combiner that simultaneously guides the video (video light) and the external image (external light) provided from the video display unit 11 to the eyes of the observer.

  As described above, in each of the video display units 1R and 1L, the optical element 24 of the eyepiece optical system 21 is composed of the volume phase type reflective HOE, and the video light from the LCD 15 is magnified and reflected by the HOE. In addition to guiding the observer's eyes as a virtual image, the light of the external image transmitted through the HOE is guided to the observer's eyes. Thus, since the HOE also serves as an eyepiece optical system, the video display units 1R and 1L can be reduced in size and weight. In addition, since the volume phase reflection type HOE has a narrow half-value wavelength width of diffraction efficiency, the light transmittance of the external image becomes high and the external image can be clearly observed. Further, since the HOE has a positive non-axisymmetric optical power for enlarging the image displayed on the LCD 15, it can observe a well-corrected aberration-corrected image while making the eyepiece optical system 21 compact. Can be provided.

  Further, as described above, the optical element 24 is composed of the volume phase type reflection type HOE that diffracts only the light having the specific incident angle and the specific wavelength, so that the image light from the LCD 15 is converted into the eyepiece prism 22 and the deflection prism. 23 and the light of the external image transmitted through the optical element 24 is not affected. That is, since the volume phase type reflection type HOE has both high wavelength selectivity and angle selectivity, it has a diffractive reflection effect only on light in a limited wavelength range. The HOE can function as a combiner element that synthesizes transmitted light of other wavelengths. Therefore, the observer can observe the external image clearly and normally through the eyepiece prism 22, the deflection prism 23, and the optical element 24 while observing the virtual image of the display image on the LCD 15 through the optical element 24. it can.

  Further, since the optical element 24 is a combiner that guides image light and external light simultaneously to the observer's pupil, the observer can observe the image provided from the LCD 15 via the eyepiece optical system 21. At the same time, an external image can be observed through the eyepiece optical system 21 with see-through. Further, since the optical element 24 is embedded between the joint surfaces of the eyepiece prism 22 and the deflecting prism 23, the optical element 24 does not come into contact with outside air, and the optical performance of the optical element 24 can be kept stable.

  Further, in the video display units 1R and 1L, the video light emitted from the LCD 15 is incident on the inside through the surface 22a of the eyepiece prism 22, and is internally internally reflected a plurality of times and guided to the optical element 24. As a result, the thickness of the eyepiece prism 22 and the deflection prism 23 can be reduced to about 3 mm as in the case of a normal spectacle lens, and the eyepiece optical system 21 and thus the video display unit 1R / 1L can be reduced in size and weight. . Furthermore, the video display unit 11 can be arranged at a position far away from immediately before the eyes of the observer, and a wide field of view of the observer with respect to the outside world can be secured. In addition, since the reflection in the eyepiece prism 22 is total reflection, the external light is transmitted through the both surfaces (surfaces 22b and 22c) of the eyepiece prism 22 without reducing the transmittance, and an external image is displayed to the observer. Can be observed.

  In addition, since an LED is used as the light source 12, a bright image can be provided to the observer by combining the emission wavelength of the LED and the diffraction wavelength of the HOE. In particular, since the light source 12 is composed of LEDs that emit RGB light, it is possible to display color images with the LEDs 15 and to allow the observer to observe color images even during binocular observation. Become.

  Further, since the light source 12 is disposed in the vicinity of the object side focal point of the condenser lens 14 and the eyepiece optical system 21 is a telecentric optical system, the light source 12 and the observation pupil E are in a substantially conjugate positional relationship. However, since the light from the light source 12 is diffused by the one-way diffusion plate 13, the light source 12 and the observation pupil E are in the diffusion direction of the one-way diffusion plate 13, that is, the direction in which the light emitting units of the light source 12 are arranged (for example, the horizontal direction). ) Is not actually conjugate, but is substantially conjugate in a direction perpendicular to the above direction. Thereby, in the said vertical direction, the light from the light source 12 can be efficiently guide | induced to the observation pupil E, and it becomes possible to make an observer observe a bright image | video at the position of the observation pupil E. Further, since the position with the strongest intensity in the observation pupil E substantially coincides with the position conjugate with the light source 12, the LCD 15 is illuminated with a substantially parallel light beam (Kohler illumination). Unevenness can be made relatively small in the display screen of the LCD 15.

  In each of the video display units R and L, the HOE constituting the optical element 24 is manufactured to satisfy 0.98 ≦ (λx / λ0) ≦ 1.02, as described above. Thus, when the value of λx / λ0 is close to 1, the difference between λx and λ0 is small (because the difference in diffraction peak wavelength between the center and the end of the viewing angle is small), the observer can observe The color unevenness in the image E can be observed very small.

  Since the three light emission points of RGB of the light source 12 (positions of the respective light emitting units) are different, color unevenness occurs on the observation pupil E when the diffusivity of the unidirectional diffusion plate 13 is small as in this embodiment. (See FIG. 1). However, in the present embodiment, conversely, this is utilized so that an individual with different eye widths can observe an image with reduced color unevenness as a binocular observation image. This point will be described later.

  The positional relationship between the unidirectional diffuser 13 and the condenser lens 14 may be reversed. That is, the light from the light source 12 may be collected by the condenser lens 14, diffused by the unidirectional diffusion plate 13, and incident on the LCD 15 (see FIG. 8).

(3. Method for manufacturing optical element)
Next, a method for manufacturing the above-described optical element 24 will be briefly described.
The HOE constituting the optical element 24 is produced, for example, by attaching a multilayer film, which is an optical film, onto the eyepiece prism 22 and exposing it with laser light. The multilayer film includes a base film, a barrier film, a photosensitive film, and a cover film that are overlapped in this order. The base film, the barrier film, the photosensitive film, and the cover film have thicknesses of, for example, 50 μm, 5 μm, 20 μm, and 50 μm, respectively.

  Photosensitive materials constituting the photosensitive film include photopolymers, silver salt materials, dichromated gelatin, etc. In this embodiment, HOE as the optical element 24 can be easily manufactured by a dry process. Photopolymer is used. In particular, the photosensitive film is composed of a single-layer or three-layer photopolymer having sensitivity to wavelengths corresponding to three primary colors of R (red), G (green), and B (blue).

  The manufacturing process of the optical element 24 using the above multilayer film is as follows. First, a multilayer film is cut out from the original film. At the same time, in the multilayer film, a cut is also made at the boundary between a region that needs to be attached to the eyepiece prism 22 and a region that is formed around the region and does not need to be attached. And after peeling a cover film from a multilayer film and positioning a multilayer film with respect to the eyepiece prism 22, a multilayer film is affixed on the joint surface of the eyepiece prism 22 by pressing with a rubber roller. At this time, the photosensitive film side of the multilayer film is set to the eyepiece prism 22 side. Then, the application unnecessary area is peeled off and the base film of the application required area is also peeled off so that only the application required area remains on the joint surface of the eyepiece prism 22.

  Finally, a coherent laser beam is irradiated onto the photosensitive film with two light beams, and an HOE is produced by the interference of the two light beams. At this time, by using a laser light source that emits light of three colors of RGB as laser light, an HOE that functions for the three colors of RGB, that is, an HOE that diffracts and reflects RGB light can be manufactured.

(4. Method for reducing color unevenness)
Next, a method for reducing color unevenness of an observation image in the present embodiment will be described. A specific configuration of the video display units 1R and 1L that realizes the reduction method will be described later.

For convenience of explanation below, it is assumed that the LCD 15 of the video display unit 1R is the video display element R, and the observation pupil E is the observation pupil E _R. Similarly, the LCD 15 of the video display unit 1L is the video display element L, and the observation pupil E is the observation pupil E _L. In addition, when an image is displayed on the image display element R, an observation image observed with the right eye of the observer is referred to as an observation image R. Similarly, when an image is displayed on the image display element L, an observation image observed with the left eye of the observer is referred to as an observation image L. Further, an observation image with both eyes, which is formed by adding the observation image R and the observation image L, is referred to as an observation image B.

  In the present embodiment, since the RGB integrated LED is used as the light source 12, all the RGB light emitting units are turned on, and all the pixels of the image display elements R and L are in the light transmitting state or the light reflecting state. Then, a white plain image is displayed on the image display elements R and L. For this reason, making all the pixels of the video display elements R and L light transmission state or light reflection state is also simply referred to as white display state, and particularly when emphasizing that both are white display states, Both are also referred to as white display states.

FIG. 1 is an explanatory diagram illustrating an example of a color distribution in the observation pupils E _R and E _L when both are in the white display state. In FIG. 1, the narrower the interval between the vertical lines in the observation pupils E _R and E _{L is} , the more white the color is reddish or bluish, and the wider the interval is, the closer the color is to white. In the both white display state, it is ideal that a white image having no color unevenness is observed in the entire region in the observation pupils E _R and E _L , but for example, three light emitting portions (LED or the like) of RGB are used as the light source 12. In reality, the observation pupils E _R and E _L are affected in the eye width direction by the influence of the difference in position of the light emitting portions of the three colors, the difference in the intensity distribution due to the radiation angle, the angle selectivity of the HOE, and the like. Intra-pupil color distribution (color unevenness) with different image colors depending on the position occurs. Here, as an example, in the observation pupils E _R and E _L , both “bluish white”, “white”, and “reddish white” are continuous in the direction from the left side to the right side in the eye width direction. There is a color distribution in which the color changes. That is, the observation pupils E _R and E _L are arranged in the eye width direction with the same intra-pupil color distribution.

Therefore, when the observer's right eye and left eye are positioned in the vicinity of the center of the observation pupils E _R and E _L (see eye width distance (1)), the observation images R and L have the same color (both “white” ]). Further, when the observer's right eye and left eye are located at positions equidistant from the center of each of the observation pupils E _R and E _L inward in the eye width direction (see eye width distance (2)), the observation image R and the observation image L have different colors (the observation image R is “blue white” and the observation image L is “red white”) (see FIG. 5). Further, even when the right and left eyes of the observer are located at positions equidistant from the center of each of the observation pupils E _R and E _{L in} the lateral direction of the eye width (see eye width distance (3)), the observation is performed. The image R and the observation image L have different colors (the observation image R is “reddish white” and the observation image L is “bluish white”).

That is, in this example, when observing with only one eye, the observation image L becomes a target white image in the vicinity of the center of the observation pupil E _L L in the eye width direction, but approaches the periphery in the left-right direction of the observation pupil E _L. As a result, the inside becomes a reddish white image and the outside becomes a bluish white image. That is, the observation image L observed by the observer with a narrow eye width with the left eye becomes a reddish white image, and the observation image L with the observer with a wide eye width observed by the left eye becomes a bluish white image. On the other hand, the opposite of the observation image R, the observation image R observed by the right eye by an observer with a narrow eye width becomes a bluish white image, and the observation image R observed by the right eye by a viewer with a wide eye width is red. It looks like a white statue.

It should be noted that although there are individual differences in the distance between the eyes of a human, it is generally said that about 90% or more of the people belong to an eye width range of 58 to 70 mm. In order to allow an observer in this range to observe the image satisfactorily, the difference of 12 mm can be compensated for by the observation pupil E _R · E _L (that is, the observation pupil E _R · E _L of about 6 mm in the left-right direction per eye). Is required. Therefore, in this embodiment, the observation pupil E when the lateral direction of the magnitude of the _R · E _L and 6 mm, the observation pupil E _R · E _L around the observation pupil range of about each 1.5mm to the right and left from E _R of · E and _L near the center of the area of a region outside the region near the center, observing the pupil E _R · region of about two ends approximately 1.5mm of E _L, observation pupil E _R · E in _L The area where the colors are observed differently on the left and right.

As described above, in the both white display state, the intra-pupil color described above for the observation pupils E _R and E _L so that the colors of the observation images R and L change according to the positions of the right and left eyes of the observer. By generating a distribution (color unevenness) and making the change in the color distribution in the pupil the same in the eye width direction in the observation pupils E _R and E _L , an observer with an eye width distance different from the designed eye width distance On the other hand, it is possible to observe images of different colors on the left and right.

Here, FIG. 5 is an observation image L observed with the left eye of an observer with a narrow eye width (an observer having the eye width distance (2) in FIG. 1) in both white display states, and is observed with the right eye. The observed image R and the observed image B observed with both eyes are schematically shown. As described above, an observer with a narrow eye width observes a reddish white image on the entire screen with the left eye, and a bluish white image on the entire screen with the right eye. An image having a color different from that of the desired image (in this case, white) is observed (an observer with a wide eye width observes an image having a color opposite to that described above with the left eye and the right eye). However, by viewing these images with both eyes, the observation image B with both eyes is recognized as a color obtained by superimposing the observation image R with the right eye and the observation image L with the left eye. An image close to the color (in this case, white) at the center of the design observation pupil that is desired to be observed can be observed. That is, although the color unevenness in the observation pupils E _R and E _L is large, it is as if the observer is observing an image with the video display device 1 with small color unevenness in the pupil by binocular observation. Can observe the video. Therefore, efforts to reduce color unevenness in individual pupils are reduced.

In order to reduce the color unevenness in each pupil, for example, there is a method of increasing the diffusivity of the unidirectional diffusion plate 13, but in this embodiment, an image with reduced color unevenness is observed by binocular observation. Therefore, it is not necessary to increase the diffusivity of the unidirectional diffusion plate 13 as described above. In addition, by allowing an observer with an eye width different from the designed eye width distance to observe images of different colors on the left and right, an image with reduced color unevenness is observed as an observation image B with both eyes. Therefore, it is not necessary to provide a conventional eye width adjustment mechanism or to form the observation pupils E _R and E _L by a plurality of pupils in order to cope with the difference in eye width. As a result, it is possible to allow a viewer having an eye width different from the designed eye width distance to observe a bright image with high image quality with a simple configuration without the eye width adjusting mechanism.

In particular, in the present embodiment, as shown in FIG. 1, in both white display states, the observation pupils E _R and E _L are aligned in the eye width direction with the same intra-pupil color distribution. The observation images R and L when the right eye and the left eye are located in the vicinity of the centers of _R and E _L have the same color, and the inner sides or the outsides of the eyes in the width direction from the centers of the observation pupils E _R and E _L , respectively. The observation images R and L when the right eye and the left eye are located at positions equidistant from each other can have different colors. This allows an observer with an eye width different from the designed eye width distance to observe images of different colors on the left and right, and as an observation image B with both eyes, at the center of the observation pupils E _R and E _L An image close to the color of the image can be observed.

As shown in FIG. 1 and FIG. 5, in both white display states, the right eye and the left eye are located at positions equidistant from the centers of the observation pupils E _R and E _{L in} the width direction of the eye or in the outside of the eye width direction, respectively. The observation image B formed by adding the observation image R and the observation image L is more colored than the observation image R and the observation image L at the center of the observation pupil R and the observation pupil L. (For example, white). Therefore, the observer can visually recognize an image closer to the color (white) of the image at the center of the observation pupil R and the observation pupil L than the color of the image observed during the one-eye observation.

In the above, the same pupil color unevenness is arranged next to each other to form the observation pupils E _R and E _L. Of course, the left and right observation pupils E _R and E _L are not exactly the same in the pupil color unevenness. However, the direction of occurrence of the color unevenness may be the same direction. In any case, the in-pupil color unevenness may be generated so that the in-pupil color unevenness of the observation pupils E _R and E _L is canceled by binocular vision (due to the difference in the colors of the observation images R and L).

FIG. 6 shows XY chromaticity coordinates in the XYZ color system. Note that R ₁ , L ₁ , and B ₁ in the figure are observed with the right eye, left eye, and both eyes of an observer having the same eye width as the designed eye width distance in (both) white display states, respectively. The chromaticity coordinates corresponding to the screen centers of the observation image R, the observation image L, and the observation image B are shown. R ₂ , L ₂ , and B ₂ in the figure are observation images R and observations that are observed with the right eye, left eye, and both eyes of an observer with a narrow eye width in the (both) white display state, respectively. The chromaticity coordinates corresponding to the screen centers of the image L and the observation image B are shown. Further, R ₃ , L ₃ , and B ₃ in the figure are observation images R and observations observed with the right eye, left eye, and both eyes of the observer with a wide eye width in the (both) white display state, respectively. The chromaticity coordinates corresponding to the screen centers of the image L and the observation image B are shown. Further, P in the figure indicates a range of chromaticity coordinates corresponding to all positions in the observation pupil at the time of observation with one eye (right eye or left eye) in the white display state, and Q is both white. In the display state, a range of chromaticity coordinates corresponding to all positions in the screen of an observation image observed with both eyes is shown.

The effects of the present invention described above can also be described as follows using FIG. That is, for example, for an observer with a narrow eye width, the chromaticity coordinate corresponding to the center of the screen of the observation image L observed with the left eye is L ₂ (reddish white), and the observation image observed with the right eye The chromaticity coordinate corresponding to the center of the R screen is R ₂ (bluish white). When observing them in both eyes, observation image B is recognized as an intermediate color between L ₂ and R _2, taken an intermediate color between L ₂ and R ₂ is as chromaticity coordinates. Note that when the left and right images are observed evenly, it becomes B ₂ which is approximately an intermediate value between L ₂ and R ₂ , but since there is actually a dominant eye, the color on the dominant eye side is recognized more strongly. . For this reason, the observed image B is observed as a color slightly closer to the dominant eye side than the intermediate value. However, in any case, the color of the observation image B is a color between L ₂ and R ₂ .

As a result, the color of the observation image B in binocular vision, than when one eye observation become possible approaches to the color of observer's observation image of the design eye width (B _1), substantially as if viewing pupil E _R · E It can be observed as if it was observed with an apparatus with little color unevenness in _L. Therefore, even in a configuration in which the intra-pupil color unevenness in the observation pupils E _R and E _L is large and there is no eye width adjustment mechanism, a plurality of observers with different eye widths are located at the center of the design observation pupils E _R and E _L. It is possible to observe an image with a color close to the color of the observation image R · L.

By the way, in both the white display states, in each of the observation pupils E _R and E _L , the difference in chromaticity X coordinate value and the difference in chromaticity Y coordinate value at both ends in the eye width direction, that is, R ₂ and R ₃ , It is desirable that at least one of the difference in chromaticity X coordinate value and the difference in chromaticity Y coordinate value between L ₂ and L ₃ is 0.05 or more. Incidentally, in this embodiment, as shown in FIG. 6, the difference between the chromaticity X coordinates in R ₂ and R ₃ and between L ₂ and L ₃ is about 0.15, and the chromaticity Y coordinate The differences are both about 0.1.

In such a state, in the observation pupils E _R and E _L , color unevenness in which the image color varies depending on the position in the eye width direction is surely generated. This makes it possible for an observer with an eye width different from the designed eye width distance to observe images of different colors with the left and right eyes, and as an observation image with both eyes, An image closer to the color of the image at the center of the observation pupils E _R and E _L can be observed than the observation image.

Further, in both the white display state, be positioned right and left eyes at any position in the observation pupil E _R · E _L, chromaticity X coordinate value of the color distribution of the observation image R · L and chromaticity It is desirable that both the Y coordinate values can be in a range of 0.03 or less. For example, FIG. 5 shows an observation image R · L observed by an observer with a narrow eye width. The right eye and the left eye of the observer at this time are respectively viewed from the centers of the observation pupils E _R · E _L. It is in a position equidistant from each other on the inner side in the eye width direction. The entire screen of the observation image R at this time is bluish white, and the chromaticity X coordinate value and the chromaticity Y coordinate value of the color distribution of the observation image R can be both 0.03 or less. I know that. Similarly, the entire screen of the observation image L is reddish white, and the chromaticity X coordinate value and chromaticity Y coordinate value of the color distribution of the observation image L can be both 0.03 or less. I know that.

As described above, the chromaticity X coordinate value and the chromaticity Y coordinate value of the color distribution of the observation image R · L are taken regardless of the position of the right eye and the left eye in the observation pupil E _R · E _L. If both of the obtained ranges are 0.03 or less, the observed images R and L have no color unevenness at a level that can be recognized as a difference in color, and the observer has no color unevenness as the individual observed images R and L. You can observe the video.

(5. Configuration for reducing color unevenness)
Next, a specific configuration of the video display units 1R and 1L that realize the above-described method for reducing color unevenness will be described.

FIG. 7 is a plan view showing an example of the arrangement of the light emitting units of the light sources 12R and 12L. As shown in the figure, the light source 12R is formed of a three-color 1-chip LED of the light emitting unit 12R _R · 12R _G · 12R _B arranged on one chip that emits light in the wavelength of the three primary colors of RGB Yes. Further, the light source 12L likewise, is composed of three-color 1-chip LED of the light emitting unit 12L _R · 12L _G · 12L _B arranged on one chip that emits light in the wavelength of the three primary colors of RGB.

In the present embodiment, the light emitting units of the light sources 12R and 12L are arranged in the same order in the eye width direction of the observer. More specifically, the light source 12R, from left to right in the horizontal direction is an eye width of the observer, the light emitting unit 12R _R · 12R _G · 12R _B are arranged in a row in this order . Also in the light source 12L, the left of the left-right direction toward the right side, the light emitting unit 12L _R · 12L _G · 12L _B are arranged in a row in this order.

FIG. 8 is an explanatory diagram showing an optical path of RGB light traveling from the light source 12L to the observation pupil E _L in the video display unit 1L, and FIG. 9 is an intensity distribution of RGB light reaching the observation pupil E _L. It is explanatory drawing which shows. Incidentally, the light intensity distribution on the optical path and the observation pupil E _R of light in the video display unit 1R is also a similar view to FIG.

As shown in FIG. 7, in the light source 12R and the light source 12L, the positions of the RGB light emitting portions are different. Therefore, as shown in FIGS. diffuser 13L, LCD15L, upon reaching the observation pupil E _L via the eyepiece optical system 21L, different intensity distribution by each location on the viewing pupil E _L, which appears as a color unevenness in the observation pupil E _L . In FIG. 9, at the left and right ends of the observation pupil E _L , the intensity ratio of B and R is about twice different, and the pupil center is recognized as a color difference. In particular, if the light source and the optical pupil are in a substantially conjugate positional relationship, the color unevenness in the display screen can be made relatively small. However, if the diffusivity on the diffusion plate is reduced for bright observation, the color unevenness in the pupil is appear.

  In order to allow observers with different eye widths to observe images well without providing an eye width adjustment mechanism, the diffusivity of the diffusing plate used in one-eye observation is to reduce the color unevenness in the pupil as described above. To reduce the light amount difference between the center and the periphery of the screen, and to make the RGB light amount ratios at each position substantially equal. However, with this method, the light use efficiency of the illumination light is reduced, so the image is dark.

  On the other hand, in the present embodiment, the light emitting units of the light sources 12R and 12L are arranged in the same order in the eye width direction, so that an observer with an eye width different from the designed eye distance can be obtained. In single-eye viewing, both the left and right eyes observe images that differ in color from the images that they originally want to observe. An image close to can be observed. Thereby, although the color unevenness in the observation pupils of the left and right eyes is large, the observer can observe as if observing with a video display device with small color unevenness in the pupils.

That is, as in the present embodiment, in the light sources 12R and 12L, the light emitting units are arranged in the same order in the observer's eye width direction, and the same color unevenness is generated in the left and right observation pupils E _R and E _L. By doing so, it is not necessary to individually reduce the left and right intra-pupil color unevenness, and it is not necessary to increase the diffusion degree of the diffusion plate (for example, 40 degrees in the horizontal direction). This makes it possible to observe the video more brightly. In addition, it is not necessary to make the intensity ratio of light of a plurality of wavelengths uniform at all positions in the pupil.

Note that the color unevenness reducing method described in the present embodiment is a level that does not feel as color unevenness when the intensity ratio of each color is about 1: 0.8 in the observation pupils E _R and E _L. It is considered more effective when the intensity ratio of each color differs by 20% or more from the ideal intensity ratio of each color (in this case, the intensity ratio of each color at the center of the screen).

  In the above description, the example in which the light sources 12R and 12L are configured by three-color light sources that emit light of three colors of RGB has been described. However, the light sources 12R and 12L may be configured by two-color light sources that emit light of two colors. You may be comprised with the light source which light-emits four or more colors of light. In any case, in the light sources R and L, the light emitting units may be arranged in the same order in the eye width direction of the observer. In addition, the RGB light emitting units do not have to be arranged completely in a line in the eye width direction. For example, the RGB light emitting units are arranged in a substantially line in the eye width direction, that is, the remaining light emitting units are slightly shifted in the vertical direction with respect to a straight line connecting the two light emitting units (matching the eye width direction). It may be.

(6. About specific examples of diffusion setting)
Next, a specific example relating to the setting of the lateral diffusion degree of the unidirectional diffusion plate 13 will be described.
As described above, there are individual differences in the distance between the eyes of humans, but even if the eye width range is estimated to be wide, almost all people are included in the range of 54 to 72 mm (63 ± 9 mm). Therefore, in order to enable observation of an image without the eye-width adjustment mechanism, it is considered that the left and right observation pupils E _R and E _L need only be about 9 mm in the lateral direction with 63 mm as the center.

Therefore, here, designed to the left and right lateral about 10mm with a margin of length of (interpupillary distance direction) of the observation pupil E _R · E _L, in order to realize such observation pupil E _R · E _L In addition, two pairs of RGB light emitting portions (LEDs) constituting the light sources 12R and 12L are used for each eye, and two sets of pupils are combined to form observation pupils E _R and E _L , respectively.

Further, here, it is assumed that the positional relationship between the light sources 12R and 12L and the observation pupils E _R and E _L is substantially conjugate, and the LEDs used as the light sources 12R and 12L are of one chip of three colors of RGB, and the chip outer shape Was 3 mm, and the RGB inter-chip distance was 0.5 mm. Furthermore, the focal length of the condenser lens 14 was about 7 mm, and the focal length of the eyepiece optical system 21 (HOE) was about 20 mm.

Since the positional relationship between the light sources 12R and 12L and the observation pupils E _R and E _L is substantially conjugate, luminance unevenness and color unevenness in the display screens of the LCDs 15R and 15L can be made relatively small. since the position of the light-emitting portion is different, the diffusion degree in one direction diffuser plate 13R-13L is small, brightness unevenness and color unevenness occurs on the observation pupil E _R - E _L. In the above case, since the ratio of the focal length of the illumination system and the eyepiece system is 20/7 ≒ 3, the distance between chips of the LED is increased by about three times over the observation pupil E _R · E _L.

Here, FIG. 10 is an explanatory view showing expand a schematic structure of one of the video display unit 1L along the optical path, FIG. 11, the light intensity on the observation pupil E _L in the video display unit 1L It is explanatory drawing which shows distribution. Incidentally, the same as in FIG. 10 and FIG. 11 also the light intensity distribution of the other video display unit 1R configuration and on the observation pupil E _R.

In FIG. 10, the RGB light emitting units of the light source 12 are arranged in the order of BGRRGB from the horizontal left to the right (GG distance 3 mm). In this configuration, on the observation pupil E _L , the maximum intensity positions of the two G are about 9 mm apart at about 3 times 3 mm (by the way, about 12 mm for B and about 6 mm for R). Since the intensity of G at the center of the pupil is low as it is, a unidirectional diffusion plate 13L that diffuses 40 degrees in the horizontal direction is used so that about 50% of the peak position is at the center of the pupil (vertical). The diffusivity in the direction is, for example, 0.2 degrees). The one-way diffusion plate 13L is disposed at a position separated from the light source 12L by about 4 mm in the optical axis direction.

Since the intensity of each of the two Gs at the center of the pupil is about 50% of the peak intensity, the intensity after the synthesis of the two Gs is about 100% at the center of the pupil, resulting in FIG. Thus, the intensity distribution is flat in the lateral direction. Note that the intensity of the two Rs after synthesis is higher than G at the center of the pupil because the R light emitting part is arranged on the inner side (optical axis side) than the G light emitting part, and the pupil peripheral part. Is lower than G. Conversely, the intensity of the two Bs after synthesis is lower than G at the center of the pupil because the B light emitting part is arranged outside the G light emitting part (opposite the optical axis). It is higher than G at the pupil periphery. However, when the intensity ratio is about 1: 0.8, it is a level that does not feel as color unevenness, and in the entire left and right 10 mm of the observation pupil E _L , there is almost no color unevenness in the pupil.

In contrast, FIG. 12 is an explanatory view showing expand another configuration of one of the video display unit 1L along the optical path, FIG. 13, the video display unit on the observation pupil E _L in 1L It is explanatory drawing which shows light intensity distribution. Incidentally, the same as in FIG. 12 and FIG. 13 also the light intensity distribution of the other video display unit 1R configuration and on the observation pupil E _R.

  In FIG. 12, the RGB light emitting units of the light source 12 are arranged in the order of RGBRGB from left to right in the horizontal direction. In this example, a one-way diffusion plate 13L having a lateral diffusivity of 20 degrees is used so that the intensity after the synthesis of two Gs at the center of the pupil is about 80% of the peak position. (The vertical diffusion is, for example, 0.2 degrees). However, the unidirectional diffuser plate 13L is disposed 6 mm away from the light source 12L in the optical axis direction by the amount that the lateral diffusion degree is reduced to 20 degrees.

The intensity distribution of each G in the observation pupil E _L is slightly steeper than in the case of FIG. 11 because the diffusivity of the unidirectional diffusion plate 13L is low. In the configuration of FIG. 12, the BB distance and the RR distance in the light source 12L are the same as the GG distance, so that the intensity distribution after the combination of two B and the combination of two R are combined. The subsequent intensity distribution is a distribution obtained by shifting the intensity distribution after the synthesis of the two Gs to the left and right. As a result, large color unevenness occurs in the pupils at both ends of the left and right observation pupils E _R and E _L (in FIG. 13, the left end is insufficient R and the right end is insufficient B). By generating such intra-pupil color unevenness in the same direction on the left and right, observers with different eye widths can observe images without color unevenness with both eyes.

  As described above, by reducing the lateral diffusivity of the unidirectional diffuser plate 13 from 40 degrees to 20 degrees, the disposition distance of the unidirectional diffuser plate 13 with respect to the light source 12 is slightly increased, but the brightness is reduced to 2 It was found that it was possible to observe an image that was increased by a factor of about two.

  In the above example, the LED chip outer shape is as large as 3 mm with respect to the pupil size of 10 mm in the horizontal direction. Therefore, the effect of increasing the brightness is at most twice, but the LED chip size is 2 mm. If a smaller LED is used as the light source 12, the LED intensity peak position interval on the pupil can be narrowed as 6 mm, and more light can be collected at the center. As a result, it is possible to use a diffusion plate having a lower diffusivity in the lateral direction, and it is possible to brighten the center of the pupil while generating more color unevenness at both ends of the pupil.

  In other words, as the LED chip size becomes smaller with respect to the pupil size, conventionally, it is necessary to increase the diffusivity of the diffusion plate in order to eliminate the color unevenness in the pupil. In the present invention in which observers with different eye widths are observed with no image, the diffusivity of the diffusion plate can be reduced, and the present invention becomes more effective.

  Note that the lateral diffusivity of the diffusing plate is, for example, the chip size of the LED used (distance between the chips of each color), the arrangement position of the diffusing plate, the focal length of the illumination lens (condensing lens 14), and the focal point of the eyepiece optical system 21. What is necessary is just to set suitably in consideration of distance etc.

  Of course, the video display units 1R and 1L and thus the HMD can be configured by appropriately combining the configurations and methods described above.

  INDUSTRIAL APPLICABILITY The present invention can be used for an image display apparatus and an HMD capable of binocular observation.

It is explanatory drawing which shows an example of the color distribution in the right and left observation pupil in the both white display state observed with the video display apparatus of HMD which concerns on one Embodiment of this invention. (A) is a top view which shows the outline structure of HMD, (b) is a side view of HMD, (c) is a front view of HMD. It is sectional drawing which shows the schematic structure of the video display unit of right and left of the said video display apparatus. It is explanatory drawing which expand | deploys and shows the optical path of the light in the said video display unit on either side. It is explanatory drawing which shows typically each observation image observed with the left eye of the observer with a narrow eye width, a right eye, and both eyes in both white display states. It is explanatory drawing which shows the XY chromaticity coordinate in an XYZ color system. It is a top view which shows an example of arrangement | positioning of each light emission part of a light source on either side. FIG. 6 is an explanatory diagram showing an optical path of RGB light from a light source toward an observation pupil in a left-eye video display unit. It is explanatory drawing which shows intensity distribution of the RGB light on the said observation pupil. It is explanatory drawing which expands and shows the structure of the video display unit in which each light emission part of RGB of a light source is arrange | positioned along with BGRRGB in order. It is explanatory drawing which shows the light intensity distribution on the observation pupil in the said video display unit. It is explanatory drawing which expand | deploys the schematic structure of the video display unit in which each light emission part of RGB of a light source is arrange | positioned in order of RGBRGB along the optical path. It is explanatory drawing which shows the light intensity distribution on the observation pupil in the said video display unit.

Explanation of symbols

1 video display device 1R video display unit (video display unit R)
1L video display unit (video display unit L)
2 Supporting means 12 Light source 12R Light source (light source R)
12R _R light emission part 12R _G light emission part 12R _B light emission part 12L Light source (light source L)
12L _R light emitting unit 12L _G light emitting unit 12L _B light emitting unit 15 LCD (video display element, video display element R, video display element L)
21 Eyepiece optical system (eyepiece optical system R, eyepiece optical system L)
22 Eyepiece prism (joint optical member)
22a surface (incident surface)
23 Deflection prism (bonding optical member)
24 Optical elements (hologram optical elements)
E Observation pupil (observation pupil R, observation pupil L)
E _R observation pupil (observation pupil R)
_EL observation pupil (observation pupil L)

Claims (14)

A video display device including a video display unit R for the right eye and a video display unit L for the left eye,
The video display unit R
A light source R, an image display element R that displays an image by transmitting or reflecting light from the light source R for each pixel, and an eyepiece optical system R that guides the image light from the image display element R to an observation pupil R Has
The video display unit L is
A light source L, a video display element L that displays video by transmitting or reflecting light from the light source L for each pixel, and an eyepiece optical system L that guides video light from the video display element L to the observation pupil L Has
When the images observed with the right eye and the left eye are an observation image R and an observation image L, respectively,
When all the pixels of both the image display elements R and the image display elements L are in a light transmission state or a light reflection state, the observation pupil R and the observation pupil L have pupils whose image colors differ depending on the position in the eye width direction. When the right eye and the left eye are located near the centers of the observation pupil R and the observation pupil L, the observation image R and the observation image L have the same color, and the observation pupil R and the observation pupil L are the same color. The observation image R and the observation image L when the right eye and the left eye are located at equal distances from the center of the pupil L to the inner side or the outer side in the eye width direction are different colors. Video display device.   When all the pixels of both the image display elements R and the image display elements L are set to the light transmitting state or the light reflecting state, from the centers of the observation pupil R and the observation pupil L to the inside or outside of the eye width direction, respectively. The observation image R and the observation image B formed by adding the observation image R and the observation image L to each other than the observation image R and the observation image L when the right eye and the left eye are located at a distance away from each other are observed. The video display device according to claim 1, wherein the video display device is close to the color of an image at each center of the pupil L.   When all the pixels of both the image display elements R and the image display elements L are in a light transmission state or a light reflection state, the intra-pupil color distribution in the observation pupil R and the observation pupil L is expressed in XY chromaticity coordinates in the XYZ color system. In each of the observation pupil R and the observation pupil L, at least one of the difference between the chromaticity X coordinate values and the difference between the chromaticity Y coordinate values at both ends in the eye width direction is 0.05 or more. The video display device according to claim 1, wherein the video display device is a video display device.   When all the pixels of both the image display elements R and the image display elements L are set to the light transmission state or the light reflection state, the color distribution in the observation screen of the observation image R and the observation image L is changed to the XY color in the XYZ color system. When expressed in degree coordinates, the chromaticity X coordinate value and color of the color distribution of the observation image R and the observation image L, regardless of whether the right eye or the left eye is located in the observation pupil R or the observation pupil L. The video display device according to any one of claims 1 to 3, wherein both of the possible range of the degree Y coordinate value are 0.03 or less.   When all the pixels of both the image display elements R and the image display elements L are in a light transmission state or a light reflection state, the observation pupil R and the observation pupil L have the same intra-pupil color distribution in the eye width direction. The video display device according to claim 1, wherein the video display devices are arranged side by side. The light source R and the light source L are each composed of a plurality of light emitting units that emit light of different wavelengths,
6. The video display device according to claim 1, wherein in the light source R and the light source L, the light emitting units are arranged in the same order in the eye width direction of the observer.   The video display device according to claim 6, wherein the plurality of light emitting units respectively emit light having wavelengths corresponding to the three primary colors.   8. The video display according to claim 6, wherein in each of the video display unit R and the video display unit L, the light source and the observation pupil are substantially conjugate in a direction perpendicular to a direction in which the light emitting units are arranged. apparatus.   In each of the image display unit R and the image display unit L, the eyepiece optical system includes a volume phase type reflection hologram optical element, and the image light from the image display element is magnified and reflected by the hologram optical element so that the observer's The video display device according to claim 1, wherein the video display device guides the light of an external field image transmitted through the hologram optical element to an eye of an observer while guiding the virtual image to the eye. In each of the video display unit R and the video display unit L, the hologram optical element has a plurality of diffraction peak wavelengths at which the diffraction efficiency has a maximum value, and is emitted from the center of the video display element with respect to each diffraction peak wavelength. The diffraction peak wavelength of the principal ray incident on the center of the observation pupil is λ0, and the diffraction peak wavelength of the principal ray emitted from the peripheral portion of the image display element and incident on the center of the observation pupil is λx.
0.98 ≦ (λx / λ0) ≦ 1.02
The video display device according to claim 9, wherein:   In each of the video display unit R and the video display unit L, the eyepiece optical system includes a cemented optical member in which a hologram optical element is embedded, and the video light from the video display element is incident from the incident surface of the cemented optical member. The image display device according to claim 9, wherein the image display device is internally reflected a plurality of times and guided to the hologram optical element.   12. The image display device according to claim 9, wherein the hologram optical element has a positive non-axisymmetric optical power for enlarging an image displayed on the image display element. .   The video display device according to any one of claims 9 to 12, wherein in each of the video display unit R and the video display unit L, the light source is formed of a light emitting diode. A video display device according to any one of claims 1 to 13,
A head-mounted display comprising: support means for supporting the video display device in front of an observer's eyes.

Images