JP4581587B2 - Video display device - Google Patents

Description

  The present invention relates to a video display device that provides a virtual image of a displayed video superimposed on the outside world viewed by a user, and more particularly to a video display device used in a dark place.

  Personal video display devices have been developed that allow the user to observe the outside world while observing the video. Such a video display device can be used in daily life, and by displaying information in characters, it can assist people with hearing impairments and provide explanations where quietness is required Expected to be useful.

  In order to use the above-described video display device in front of the eyes, it is generally configured to be worn on the head, such as glasses, and is required to be small and light. In addition, it is necessary that the display unit that displays the video does not block light from the outside world, and a large video is provided while the display unit is small, and further provided from the eyes of the observer (user). It is also necessary to secure a certain distance to the image.

  For this reason, the display unit is arranged at a position deviated from immediately before the eye, and a combiner that combines the light from the display unit and the light from the outside world and guides it to the eye is arranged just before the eye, and the display unit guided to the eye An eyepiece optical system is arranged in the optical path from the display unit to the combiner so that the light from the image represents an enlarged virtual image of the image displayed on the display unit.

As the display unit, for example, as disclosed in JP-A-2002-18158, a combination of a liquid crystal display element (LCD) that modulates illumination light and a light source that emits illumination light, or a plurality of light emitting diodes (LEDs) ) Can be used.
JP 2002-18158

  A conventional video display device that allows a virtual image of a video to be observed over the outside world is configured for use in a bright environment, and makes it easy to observe a video (virtual image) that overlaps the bright outside world as much as possible. Consideration has been made. However, the current situation is that little consideration is given to use in a dark environment.

  When providing video over a dark external environment, if the background part of the video, that is, the part other than the display content such as characters is completely dark, only the display content is observed, and the part of the external world that overlaps the video background Is observed in the same darkness as when no image is present. However, if the contrast of the image is low and the background is somewhat bright, a clear boundary is formed between the portion of the outside world that does not overlap the image and the image, and the user feels uncomfortable. Also, it is difficult to observe the part of the outside world that overlaps the background of the video.

  An example of use in which such a situation occurs is shown in FIG. FIG. 12 shows a case where the image display apparatus is used for explaining a celestial body using a planetarium. A dark night sky is represented as the outside world Ex, and an image (virtual image) D is displayed over the part. Video D includes display content Da and background Db. The external environment Ex when the video display device is not used is as shown in FIG. 12 and 13, the constellation and the display content Da are shown dark (in black) and the background Db is shown bright (in white), but actually the constellation and display content Da are bright. Displayed, background Db is dark.

  However, the contrast of the image D is not so high, and the background Db is not completely dark. For this reason, the outline of the image D is clear, and the portion of the external environment Ex that overlaps the background Db is difficult to see.

  As described above, as a display element that displays an image, a modulation display element that modulates illumination light to display light, such as an LCD, and a self-emission that emits light that displays an image, such as an LED. There is a display element. Among these, in the self-luminous display element, the luminance of the pixel in a state where no image is displayed is extremely low. On the other hand, in the modulation display element, pixels in a state where no video is displayed have a certain level of luminance. This is one of the causes that the background to be darkened does not completely darken.

  Human vision adapts to the brightness of the environment, and the relative visual sensitivity to light of the same wavelength differs between when light is adapting and when darkly adapting. Since conventional video display devices are premised on use in a bright environment, the wavelength of light representing the video is determined based on the light adaptation relative visibility, which also reduces the contrast of the video and reduces the background. Cause bright observation.

  Further, since the brightness of the display content is set so as to be suitable for use in a bright environment, there is also a problem that when used in a dark environment, the display content becomes too bright and the user feels dazzling.

  The present invention has been made in view of such problems, and is an image display device that provides an image superimposed on the outside world and is used in a dark environment, and the background portion of the provided image is sufficient. An object is to realize a dark thing and a thing whose display contents are bright enough not to make the user feel dazzling.

In order to achieve the above object, in the present invention, a display unit that displays an image, a combiner that superimposes light representing the image from the display unit on light from the outside world and guides the viewer's eyes, and an observer's eyes In a video display device that has an eyepiece optical system that allows light from a guided display section to represent a virtual image, and is used in a dark environment, the display section includes a self-luminous display element that emits light representing the video itself The luminance at the time of light emission of each pixel of the display unit is set to 10 Cd / m ² or less.

  Since this image display device displays an image by a self-luminous display element having a very low luminance when not emitting light, the background portion of the displayed image can be almost completely darkened. Further, the brightness of the display content can be suppressed to a range where the observer does not feel dazzling.

  In order to achieve the above object, the present invention also includes a display unit for displaying an image, a combiner that superimposes light representing the image from the display unit on the light from the outside, and guides the viewer's eyes. In an image display device used in a dark environment, the display unit displays an image with only red light, and has an eyepiece optical system that allows the light from the display unit guided to a virtual image to represent a virtual image. .

  The wavelength range of light that can be perceived by human vision is different between light adaptation and dark adaptation, and red light with high relative visibility when light adaptation is dark adaptation. When this occurs, the relative visibility is greatly reduced. In this video display device, video is displayed with red light, so even if there is some brightness in the background, it will not be perceived by the user's vision, thus preventing the background from being observed brightly can do.

  Here, the wavelength of the light of the image displayed on the display unit may be 590 nm or more. At such a wavelength, the dark adaptation specific luminous sensitivity is a fraction of the light adaptation specific luminous sensitivity, and it is easy to prevent the background from being observed brightly.

The luminance when each pixel of the display unit is not displayed is preferably 1 Cd / m ² or less. Since the image is displayed with red light having a low dark adaptation specific visibility, the brightness of the non-display pixels forming the background is suppressed to this level, so that the background is surely prevented from being observed brightly.

In addition, the luminance at the time of display of each pixel of the display unit is preferably 10 Cd / m ² or less. If the image is displayed with red light having low dark adaptation specific visibility and the luminance of the pixels constituting the display content is set in this way, it is possible to reliably prevent the viewer from feeling dazzled.

  The combiner is preferably a volume phase reflection hologram. The volume phase reflection hologram is thin and lightweight, and has high wavelength selectivity, so that almost all light from the outside can be transmitted. Therefore, the observer can clearly observe the dark outside world.

  Here, it is preferable that the combiner has a positive optical power and serves as a part of the eyepiece optical system so that the light from the display unit guided to the observer's eye represents a virtual image of the image. By using the combiner as a part of the eyepiece optical system, a simple configuration is obtained. In particular, since a volume phase hologram is used as a combiner, it is easy to provide optical power.

  The eyepiece optical system may include a transparent plate-like member that totally reflects light from the display unit and guides it to the combiner and transmits light from the outside. In this configuration, the eyepiece optical system can be made thin and light. In addition, it is possible to guide light from the outside world to the eyes even in the vicinity of the combiner, and it is possible to secure a wide field of view because the display unit can be arranged at a position far away from immediately before the eyes.

In the video display apparatus of the present invention, it is possible to prevent the background of the video to be provided from being observed brightly, and the observer does not feel uncomfortable. In addition, it is not difficult to observe the portion of the outside world that overlaps the background of the image. Furthermore, the brightness of the pixel at the time of display is 10 Cd / m ² or less, so that the user does not feel dazzling. Therefore, the video display device is suitable for use in a dark environment.

Hereinafter, embodiments of a video display device of the present invention will be described with reference to the drawings. An optical configuration of the video display device 1 of the first embodiment is schematically shown in FIG. The video display device 1 includes a display unit 12 and an eyepiece optical system 13. As the display unit 12, an electroluminescence (EL) element 12a, which is a self-luminous display element in which each pixel corresponding to one point of an image emits light, is used. The luminance of each pixel of the EL element when not emitting light is about 0.001 Cd / m ² .

  The eyepiece optical system 13 includes a transparent substrate 13a and a semi-transmissive film 13b provided on the surface thereof. In the transparent substrate 13a, two opposing surfaces are free curved surfaces, and a semi-transmissive film 13b is provided on one of them. The semi-transmissive film 13b is set to have a transmittance of 90% and a reflectance of 10%, for example.

  The light representing the image from the display unit 12 enters the inside from the end surface of the transparent substrate 13a, is totally reflected on one surface, is incident on the semi-transmissive film 13b provided on the other surface, and is partially reflected. The The light from the display unit 12 reflected by the semi-transmissive film 13b is emitted from the transparent substrate 13a and reaches the optical pupil E. The two free-form surfaces of the transparent substrate are set so as to have a positive optical power with respect to the light from the display unit 12 as a whole, and the image displayed on the display unit 12 at the position of the optical pupil E is set. An enlarged virtual image can be observed. The distance from the optical pupil E to the virtual image is about several meters, and the size of the virtual image is more than 10 times the image displayed on the display unit 12.

  The semi-transmissive film 13b transmits most of the light from the outside, and the transparent substrate 13a transmits almost all the light from the outside, so that the user can observe the outside. The virtual image of the image displayed on the display unit 12 is observed while overlapping a part of the outside world. The semi-transmissive film 13b forms a part of the eyepiece optical system 13, and also forms a combiner that combines light from the display unit 12 and light from the outside world and guides it to the optical pupil E.

  Light from the outside world is refracted when it passes through the free curved surface of the transparent substrate 13a. In order to prevent the outside world from being distorted and observed due to the refraction, the surface on which the semi-transmissive film 13b of the transparent substrate 13a is provided. Is joined with another transparent substrate 14. The surface facing the bonding surface of the transparent substrate 14 is a free curved surface corresponding to the free curved surface facing the bonding surface of the transparent substrate 13, and light from the outside after passing through these two free curved surfaces is transmitted. Go straight on the extension of the previous light path. These two surfaces may be planes parallel to each other, instead of being free-form surfaces.

  The total transmittance of the transparent substrate 13a and the semi-transmissive film 13b constituting the eyepiece optical system 13 and the distortion correcting transparent substrate 14 (transmittance for all wavelengths of visible light) is about 80%, and the outside world is an image. It is observed with the same brightness as when the display device 1 is not used. Therefore, the use of the video display device 1 does not make it difficult to observe a dark external environment.

  Since the luminance of each pixel of the display unit 12 when not displaying (when not emitting light) is extremely low as described above, the background portion constituted by the non-displaying pixels in the image is almost completely dark. For this reason, there is no difference in brightness between the portion of the outside world that does not overlap the portion that overlaps the image (virtual image), and the boundary between the image and the surrounding outside is not observed. In addition, it is not difficult to observe the portion of the outside world that overlaps the image due to the background of the image.

The luminance of each pixel of the display unit 12 during display (light emission) is set within a range of 1 to 10 Cd / m ² . Therefore, the display content constituted by the display pixels is not too bright and the user does not feel dazzled. Further, since the luminance when each pixel is not displayed is extremely low, the contrast of the image displayed on the display unit 12 is high and the display content can be easily observed even when the luminance when displaying is set in such a range. .

  An example of use of the video display device 1 is shown in FIG. This is the same as in the case of FIG. 12 described above when the video display device 1 is used for explaining a celestial body using a planetarium. A dark night sky is represented as the outside world Ex, and an image (virtual image) D is displayed over the part. Video D includes display content Da and background Db. The external environment Ex when the video display device 1 is not used is as shown in FIG. Here, the constellation and the display content Da are shown dark (in black) and the background Db is shown bright (in white). However, actually, the constellation and display content Da are displayed brightly, and the background Db is dark. Furthermore, although the outline of the image D is represented by a broken line, this outline is not observed.

  Note that FIG. 2 is a usage example of the video display device of each embodiment described below, and the above description also applies to a video provided by the video display device of each embodiment.

  FIG. 3 schematically shows an optical configuration of the video display device 2 according to the second embodiment. The video display device 2 includes a display unit 12 and an eyepiece optical system 13. As the display unit 12, an EL element 12a is used as in the video display device 1 of the first embodiment. The eyepiece optical system 13 is a volume phase reflection hologram 13c. The hologram 13c is attached to the transparent substrate 14 ′.

  Light representing an image from the display unit 12 enters the volume phase reflection hologram 13c, is reflected, and reaches the optical pupil E. The hologram 13c is set so as to have a positive optical power with respect to the light from the display unit 12, and an enlarged virtual image of the image displayed on the display unit 12 can be observed at the position of the optical pupil E. .

  FIG. 4 shows the relationship between the wavelength of light and the diffraction efficiency of the volume phase reflection hologram 13c. The hologram 13 selectively diffracts and reflects light in three wavelength bands of 465 ± 5 nm, 520 ± 5 nm, and 635 ± 5 nm. The display unit 12 is set to emit light at the center wavelengths of these wavelength bands, that is, 465 nm, 520 nm, and 635 nm, and the light representing the image from the display unit 12 is efficiently reflected by the hologram 13c. The video display device 2 provides a color video.

  In general, a hologram has such a high wavelength selectivity and also has a high incident angle dependency, and acts only on light of a specific wavelength incident from a specific direction, so almost all light from the outside is diffracted. The hologram 13c is transmitted without being transmitted. Therefore, the user can observe the outside world, and the virtual image of the video displayed on the display unit 12 is observed while overlapping a part of the outside world. The hologram 13c forms a part of the eyepiece optical system 13, and also forms a combiner that combines the light from the display unit 12 and the light from the outside world and guides it to the optical pupil E.

The combined transmittance of the hologram 13c and the transparent substrate 14 ′ (transmittance with respect to all wavelengths of visible light) is about 90%. In the image display device 2, the brightness of the observed external environment is reduced. More suppressed than. In addition, the luminance at the time of display of each pixel of the display unit 12 is set within a range of 1 to 10 Cd / m ² , similarly to the video display device 1.

  FIG. 5 schematically shows an optical configuration of the video display device 3 according to the third embodiment. The video display device 3 includes a display unit 12 and an eyepiece optical system 13. As the display unit 12, an EL element 12a is used as in the video display devices 1 and 2 of the first and second embodiments. The eyepiece optical system 13 includes a transparent substrate 13a and a volume phase reflection hologram 13c.

  The transparent substrate 13 is formed in a wedge shape such that the lower end of the parallel flat plate becomes thinner as it approaches the lower end, and the upper end becomes thicker as it approaches the upper end. The hologram 13 is attached to the inclined surface at the lower end of the transparent substrate 13a. The display unit 12 is accommodated in a housing 11, and the housing 11 is attached to the upper end portion of the transparent substrate 13a.

  The light representing the image from the display unit 12 enters the inside of the transparent substrate 13a from the end surface, is totally reflected a plurality of times by two opposing surfaces, and enters the volume phase reflection hologram 13c. The light incident on the hologram 13c is reflected and reaches the optical pupil E. The hologram 13c is set so as to have a positive optical power with respect to the light from the display unit 12, and an enlarged virtual image of the image displayed on the display unit 12 can be observed at the position of the optical pupil E. .

  The hologram 13c is set to selectively diffract and reflect light in three wavelength bands of 465 ± 5 nm, 520 ± 5 nm, and 635 ± 5 nm, similar to that of the video display device 2. 12 is set to emit light of 465 nm, 520 nm, and 635 nm, similar to that of the video display device 2. The video display device 3 also provides a color video.

  The hologram 13c and the transparent substrate 13a transmit almost all light from the outside. Therefore, the user can observe the outside world, and the virtual image of the video displayed on the display unit 12 is observed while overlapping a part of the outside world. The hologram 13c forms a part of the eyepiece optical system 13, and also forms a combiner that combines the light from the display unit 12 and the light from the outside world and guides it to the optical pupil E.

  In order to prevent distortion from occurring in the external world observed when light from the outside passes through the wedge-shaped lower end of the transparent substrate 13a, the inclined surface provided with the hologram 13c at the lower end of the transparent substrate 13a is used. The transparent substrate 14 is bonded. The transparent substrate 14 and the transparent substrate 13 are integrated to form a parallel plate, and no distortion occurs in the observed external environment.

The total transmittance of the transparent substrate 13a, the hologram 13c, and the distortion correcting transparent substrate 14 constituting the eyepiece optical system 13 is about 90%. In the image display device 3, a decrease in the brightness of the observed external environment is displayed on the image display. It is suppressed similarly to the apparatus 2. In addition, the brightness | luminance at the time of the display of each pixel of the display part 12 is set in the range of 1-10 Cd / m < ² >.

  In the video display device 3, light from the display unit 12 is guided to the hologram 13c by total reflection in the transparent substrate 13a. It can be arranged at a position far away. For this reason, a wide field of view with respect to the outside world can be secured. The thickness of the transparent substrate 13 can be about 3 mm, and the video display device 3 is small and light.

  The appearance of the video display device 4 of the fourth embodiment is schematically shown in FIG. 6A is a front view, FIG. 6B is a top view, and FIG. 6C is a side view. The video display device 4 is used while being worn on the user's head, and provides video to one eye (right eye). The video display device 4 includes an optical module 10 for providing video. The optical module 10 includes a housing 11 that houses a display unit, and an eyepiece optical system 13.

  The casing 11 is attached to a bridge 21, and a frame 22 is attached to each of the casing 11 and the bridge 21. A temple 23 is attached to each frame 22 via a hinge, and a pair of nose pads 24 are attached to the bridge 21. The video display device 4 as a whole has a form in which one lens is removed from general glasses, and when worn, the temple 23 is supported by the temporal region and the nose pad 24 is supported by the nose.

  Connected to the optical module 10 is a cable 15 for transmitting power, a video signal, and a control signal from a control unit (not shown) to the display unit. The cable 15 is provided along one temple 23.

  FIG. 7 shows a cross section of the optical module 10 taken along line AA ′ in FIG. The optical module 10 includes a display unit 12 and an eyepiece optical system 13. The display unit 12 includes a liquid crystal display element (LCD) 12b that is a modulation display element that modulates illumination light applied to each pixel corresponding to one point of an image, a light source 12c that supplies illumination light to the liquid crystal display element 12b, and a light source 12c. A diffusing plate 12d that diffuses illumination light from the light in an inhomogeneous manner, and a condensing lens 12e that condenses the light transmitted through the diffusing plate 12d.

  The diffusing plate 12d is set to diffuse light from the light source 12c by about 40 ° in the left-right direction (direction perpendicular to the paper surface of FIG. 7) and by about 0.5 ° in the direction perpendicular thereto. . The condensing lens 12e is arranged so that the light diffused by the diffusion plate 12d efficiently forms the optical pupil E.

  The eyepiece optical system 13 has the same configuration as that of the video display device 3 of the third embodiment, and includes a transparent substrate 13a and a volume phase reflection hologram 13c. As described above, the hologram 13c also serves as a combiner that combines light from the display unit 12 and light from the outside world. A transparent substrate 14 for distortion correction is bonded to the transparent substrate 13a. The user can observe an enlarged virtual image overlapping a part of the outside world at the position of the optical pupil E.

  A field of view at the position of the optical pupil E is shown in FIG. The housing 11 that accommodates the display unit 12 exists at a position that is far away from immediately before the optical pupil E, and the vertical angle of the visual field that is blocked by the housing 11 is about 30 °. The vertical angle of the visual field of the outside world is 70 °, but is larger on the left and right sides of the housing 11. The vertical angle of the visual field of the image (virtual image) is about 10 °.

  FIG. 9 shows the relationship between the wavelength of light and the diffraction efficiency of the volume phase reflection hologram 13c. The hologram 13c is set so as to selectively diffract and reflect light in a single wavelength band of 635 ± 5 nm, and the light source 12c of the display unit 12 reflects light at the center wavelength of the wavelength band, that is, 635 nm. It is set to emit. Therefore, the video display device 4 provides a red light video. For example, a light emitting diode (LED) can be used as the light source 12c.

  FIG. 10 shows the relationship between the wavelength of light and the specific visual sensitivity of human vision. This is published in page 634 of the Optical Technology Handbook (Asakura Shoten). As is clear from FIG. 10, the wavelength band with high relative visibility when darkly adapted is on the shorter wavelength side than the wavelength band with high relative visibility when brightly adapted. The relative luminous sensitivity of red light is low.

  Light leaks from each pixel of the liquid crystal display element, which is a modulation display element, even when non-display. This amount of light is about 1/100 of the display. The same applies to the liquid crystal display element 12b of the video display device 4, and the luminance of the non-display pixel is about 1/100 of the luminance of the display pixel. However, in the video display device 4, the light representing the video is red light, that is, light having a wavelength with low relative visibility at the time of dark adaptation, so that the light leaking from the non-display pixels is observed by the user. There is almost no background of the image formed by non-displayed pixels. Therefore, no boundary is observed between the provided video (virtual image) and the surrounding background, and it is easy to observe the portion of the external world that overlaps the video background.

It is desirable that the luminance of the pixel of the liquid crystal display element 12b during non-display is 1 Cd / m ² or less. In this way, the background of the video can be surely darkened. When the brightness of the emergency pixel is 1 Cd / m ² , the brightness of the display pixel is about 100 Cd / m ² . This value is 10 to 100 times the value in the video display devices 1 to 3 of the first to third embodiments. However, since the relative luminous sensitivity of red light during dark adaptation is low, the user feels dazzling. The display content is rarely observed brightly. However, since there are individual differences in the visual perception of the user, the luminance of the display pixels is 10 Cd / m ² or less, and therefore the luminance of the non-display pixels is 0.1 Cd / m ² in order to ensure that the user is not dazzled. m ² or less is preferable.

  If the wavelength of the light emitted from the light source 12c is wide, some of the light diffracted by the hologram 13c travels in a direction slightly different from the design. For example, light having a wavelength of 635 nm and light having a wavelength of 640 nm travel in different directions after diffraction. This causes a reduction in the resolution of the provided video (virtual image). However, the angle difference is smaller for red light having a relatively long wavelength than for light having a short wavelength (for example, blue light having a wavelength of 475 nm and 480 nm). Therefore, in the video display device 1 that displays video with red light, even if the wavelength of the light emitted from the light source 12c has a width, there is little decrease in resolution.

  Since the video display device 4 is configured to be mounted on the head, the position of the provided video (virtual image) is constant. Therefore, it is easy for the user to understand where the image is even in a dark environment, which is more suitable for use in a dark environment. Here, the wavelength of the light emitted from the light source 12c, that is, the light representing the image is set to 635 nm. However, as can be seen from FIG. 10, the dark adaptation relative luminous efficiency is within the range of the light wavelength of 590 to 700 nm. Since it is substantially constant, the wavelength of light representing an image may be any value within this range. The diffraction characteristics of the hologram 13c are determined in accordance with the wavelength of light representing an image.

  The appearance of the video display device 5 of the fifth embodiment is schematically shown in FIG. In FIG. 11, (a) is a front view, (b) is a top view, and (c) is a side view. This video display device 5 is obtained by adding another optical module 10 to the video display device 4 of the fourth embodiment to provide a video (virtual image) to both eyes. The video display device 5 is generally bilaterally symmetric as a whole. Note that the cable 15 extends to one housing 11 through the other housing 11.

  The video display devices 1 according to the first to fifth embodiments can adjust the display luminance of the display unit 12 so that the display luminance can be changed according to the brightness of the environment. In that case, the display luminance may be adjusted by changing the voltage applied to the EL element 12a or the light source 12c, or by changing the luminance signal applied to the EL element 12a or the liquid crystal display element 12b. The latter is simpler and can be realized at a lower cost.

If the display brightness can be adjusted, it can be used in a bright environment. For example, external luminance is the display brightness when the 100 Cd / m ² and 200 Cd / m ^2, as external luminance is lowered, lowering the display brightness, if eventually to be the above value, Can be used in any brightness environment.

  Adjusting the display brightness according to the brightness of the environment can be performed for a plurality of video display devices by including a control unit that collectively controls the plurality of video display devices. For example, in the case of a video display device used in a planetarium, a control unit that controls the entire planetarium adjusts the display brightness of all the video display devices according to the contents to be provided.

  It is also possible to individually adjust the display brightness for each video display device according to the brightness of the environment. In that case, each video display device may be provided with an operation unit and manually adjusted by the user, or each video display device may be provided with a sensor for detecting brightness, and automatically based on the detection result. You may make it adjust to. The brightness sensor preferably detects the brightness of a portion of the outside world that overlaps the video (virtual image) provided. At that time, the average brightness of the part overlapping the video may be detected, or the brightness of the brightest part of the part overlapping the video may be detected.

  When the display brightness is adjusted individually for each video display device, even when the brightness of the environment varies depending on the direction, it is possible to provide each user with an image with appropriate brightness according to the direction that the user observes. Is possible.

  In each of the above embodiments, the electroluminescence (EL) element 12a is used as an example of the self-luminous display element. However, a light emitting diode (LED) array or a cathode ray tube (CRT) can also be used. Further, although the transmissive liquid crystal display element 12b is given as an example of the modulation display element, a reflective liquid crystal display element can also be adopted.

1 is a cross-sectional view schematically showing an optical configuration of a video display device according to a first embodiment. The figure which shows the usage example in the dark environment of the video display apparatus of each embodiment. Sectional drawing which shows typically the optical structure of the video display apparatus of 2nd Embodiment. The figure which shows the relationship between the wavelength of light, and the diffraction efficiency of the volume phase type | mold reflection hologram with which the video display apparatus of 2nd Embodiment is provided. Sectional drawing which shows typically the optical structure of the video display apparatus of 3rd Embodiment. The front view (a) which shows typically the external appearance of the video display apparatus of 4th Embodiment, a top view (b), and a side view (c). Sectional drawing which shows typically the optical module of the video display apparatus of 4th Embodiment. Sectional drawing which shows the viewing angle of the video display apparatus of 4th Embodiment. The figure which shows the relationship between the wavelength of light, and the diffraction efficiency of the volume phase type | mold reflection hologram with which the video display apparatus of 4th Embodiment is provided. The figure which shows the relationship between the wavelength of light and specific visual sensitivity of human vision. The front view (a) which shows typically the external appearance of the video display apparatus of 5th Embodiment, a top view (b), and a side view (c). The figure which shows the usage example in the dark environment of the conventional video display apparatus. The figure which shows the example of the dark environment where a video display apparatus is used.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1-5 Video display apparatus 10 Optical module 11 Housing | casing 12 Display part 12a Electroluminescent element 12b Liquid crystal display element 13 Eyepiece optical system 13a Transparent substrate 13b Semi-transmissive film 13c Volume phase type reflection hologram 14 Distortion correction transparent substrate 14 'Transparent Board 15 Cable 21 Bridge 22 Frame 23 Temple 24 Nose pad E Optical pupil D Video Da Video display contents Db Video background Ex External

Claims (6)

A display unit that displays an image, a combiner that superimposes light representing the image from the display unit on light from the outside world and directs it to the viewer's eyes, and light from the display unit that is guided to the viewer's eyes creates a virtual image of the image In an image display device having an eyepiece optical system to represent,
The luminance at the time of display of each pixel of the display unit is 10 Cd / m ² An image display device, wherein the wavelength of light of an image displayed on the display unit is 590 nm or more when set as follows. The video display device according to claim 1, wherein the display unit displays the video only with red light. The luminance when each pixel of the display unit is not displayed is 1 Cd / m ² The video display device according to claim 1, wherein: 4. The video display device according to claim 1, wherein the combiner is a volume phase reflection hologram. 5. The combiner has positive optical power, and serves as a part of an eyepiece optical system so that light from a display unit guided to an observer's eye represents a virtual image of an image. The video display device described in 1. 6. The eyepiece optical system includes a transparent plate-like member that totally reflects light from the display unit and guides the light to the combiner while allowing light from the outside to pass therethrough. Video display device.

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