JP4835327B2 - Image display device and head-mounted image display device - Google Patents

Description

  The present invention relates to a video display device, and more particularly to a head-mounted video display device.

  Conventionally, an image (image) that is detachably mounted on the observer's head or face and obtained from an image display element such as a small CRT or a liquid crystal display element is directly projected onto the observer's eyeball by an observation optical system. On the other hand, a head-mounted image display device that enables observation of a virtual image as if the image is enlarged and projected in the air, that is, an HMD (Head Mount Display) is known.

  The HMD is used as a display device for viewing content videos such as DVDs and videos, and for remote operation of industrial equipment or medical equipment, and has a wide variety of uses.

  Conventionally, such HMDs include a so-called see-through type that displays content video and various information for operation by an operator superimposed on a natural image by external light incident through the video display unit of the HMD, and external light. It is known that it is a shield type that cannot block natural light and observe a natural image.

For example, by blurring the frame around the display screen, or by reducing the contrast between the display screen and its surroundings, even if the display screen is smaller than the field of view, the line of sight is concentrated near the center of the screen. Further, a shielding type HMD technique that does not impair the sense of reality is disclosed (see Patent Document 1). The see-through type is equipped with an electronic camera that captures the scene of the outside world, and by displaying a shooting image frame indicating the shooting range of the camera as a virtual image, etc., so that a shooting operation can be easily performed without feeling a burden. HMD technology is disclosed (see Patent Document 2).
JP-A-5-328258 JP 2005-303842 A

  The HMD disclosed in Patent Document 1 is a light-shielding type HMD that does not display an image superimposed on a natural image. Therefore, the position where the image displayed on the image display unit can be visually recognized is easy to understand, and the brightness of the outside world is also high. Even if it is high, the image can be easily seen. That is, since an image can be observed by looking into the apparatus, it is not possible to recognize whether the image can be observed or whether the image is displayed. In other words, there is no need to hide the image while it is attached, and since the image can always be confirmed while the image is displayed, there was no particular problem in confirming the observation state and whether or not the image is displayed. . However, on the other hand, since it is a light-shielding type HMD, there is a problem in that it cannot be used in a constantly worn state because an outside scene cannot be observed when an image is not displayed.

  On the other hand, since the HMD disclosed in Patent Document 2 is a see-through type HMD that displays a video superimposed on a natural image, the HMD can be used in a state where it is always attached regardless of whether or not video is displayed. However, when the image is dark, the image cannot be observed with the brightness of the outside world, and there is a problem that it is impossible to recognize whether the image can be observed or whether the image is displayed. In addition, in a small and light display device such as the HMD disclosed in Patent Document 2, since the optical pupil that can visually recognize the image is small, the optical pupil may deviate from the eye and cannot be observed when the image is not displayed. There is a problem that it is not possible to recognize whether or not the image can be observed and whether or not the image is displayed. Further, there is a problem that if the optical pupil is made sufficiently larger than 10 mm, the apparatus becomes large.

  Further, in the HMD disclosed in Patent Document 1 and Patent Document 2, since the light source that illuminates the image obtained from the image display element and the optical pupil are not conjugately arranged, the light use efficiency is low and the image is dark. was there.

  The present invention has been made in view of the above problems, and in a video display device capable of see-through, whether or not an image can be observed even when the image is dark or not displayed, and whether or not the image is displayed. It is an object of the present invention to provide a small and lightweight video display device that can be easily confirmed and can clearly observe an external scene with a wide field of view while being always worn.

  The above object is achieved by the invention described in any one of 1 to 19 below.

1. Display means for displaying video;
The image light from the display means is projected onto the observer's eyeball to form a first optical pupil that guides the image to the eyeball as a virtual image, and the image by the first optical pupil is superimposed on an external scene. An observation optical system that can be
Display area displaying means for displaying an index indicating a display area of an image displayed on the display means, and forming a second optical pupil that guides the index to the eyeball as a virtual image,
The first optical pupil is smaller than a range in which an external scene of the observation optical system can be observed, and the size and position of the second optical pupil substantially coincide with each other.

  2. 2. The image according to 1, wherein the first optical pupil and the second optical pupil are 1 mm or more and 10 mm or less, and a range in which an external scene of the observation optical system can be observed is 10 mm or more and 50 mm or less. Display device.

3. The display area presenting means comprises the display means and the observation optical system,
The display means includes a light source that displays the video and the index, and illuminates the video and the index,
The observation optical system forms the first optical pupil and the second optical pupil that guide the image and the index to the eyeball as virtual images,
3. The image display device according to 1 or 2, wherein the light source, the first optical pupil, and the second optical pupil are substantially conjugate.

  4). 4. The video display device according to any one of claims 1 to 3, wherein the display area presenting means displays an index indicating an end of the display area.

  5. 2. The video display device according to 1, wherein the display area presenting unit includes an index display unit that displays the index.

  6). 6. The video display device according to 5, wherein the index display unit displays the index outside the display area.

  7). The video display device according to 5 or 6, wherein the index display unit displays the index in green.

  8). The video display device according to any one of 5 to 7, wherein the index display unit displays the index having a luminance higher than a maximum luminance of the video.

  9. 9. The video display device according to any one of 5 to 8, wherein a distance between the virtual image of the index and the virtual image of the video is 1 diopter or less.

  10. 6. The video display device according to 1 or 5, wherein the display area presenting unit displays the index when the luminance of the video is equal to or lower than a predetermined level.

  11. 6. The video display device according to 1 or 5, wherein the display area presenting unit displays the index when the main power of the video display device is turned on.

  12 6. The video display apparatus according to 1 or 5, wherein the display area presenting unit displays the index having a luminance higher than half of the maximum luminance of the video.

13. The observation optical system includes a volume phase type reflection hologram optical element,
The image light from the display means is reflected by the reflection hologram optical element and projected onto an observer's eyeball to form a first optical pupil that guides the image as a virtual image to the eyeball, and the first optical 6. The video display device as described in 1 or 5 above, wherein the video image by a pupil is displayed so as to overlap an external scene.

  14 14. The video display device according to 13, wherein a half width of diffraction efficiency of the reflection hologram optical element is 5 nm or more and 10 nm or less in wavelength.

  15. 15. The video display device according to item 13 or 14, wherein the reflection hologram optical element has an axially asymmetric positive optical power.

  16. 6. The observation optical system according to 1 or 5, wherein the observation optical system includes a first transparent substrate capable of totally reflecting the image light and the index light and allowing observation through an external scene. Video display device.

17. An inclined surface that supports the reflection hologram optical element is formed at the lower end of the first transparent substrate,
17. The image display according to 16, wherein the observation optical system includes a second transparent substrate that cancels light refraction by the inclined surface and can be observed through an external scene. apparatus.

18. The light source is an LED;
14. The image display device according to 13, wherein the intensity peak wavelength of the LED is substantially equal to the diffraction peak wavelength of the reflection hologram optical element.

  19. A head-mounted video display device comprising the video display device according to 1 above.

  According to the present invention, the display area presenting means displays an index indicating the display area of the video displayed on the display means. Therefore, even when the image is dark or not displayed, it is possible to easily check whether the image can be observed and whether or not the image is displayed without the optical pupil being displaced from the eye by the index, and the image is displayed. Do not lose sight of the location. In addition, the operation of the apparatus can be confirmed. In addition, the first optical pupil is smaller than the range in which the external scene of the observation optical system can be observed, and the size and position of the second optical pupil are substantially matched. That is, the optical pupil can be reduced because the position where the image is displayed is not lost due to the index. Therefore, the apparatus can be reduced in size and weight, and a bright image can be observed, and at the same time, the outside scene can be clearly observed with a wide field of view through the observation optical system.

  The first optical pupil and the second optical pupil are 1 mm or more and 10 mm or less, and the range in which the outside scene of the observation optical system can be observed is 10 mm or more and 50 mm or less. That is, since the optical pupil is small, the apparatus can be reduced in size and weight, and the outside scene can be observed with a wide field of view since the outside scene can be observed. Thereby, for example, even when the apparatus is mounted on the head, it can be used for a long time without feeling a burden.

  Further, the display area presenting means is composed of display means and an observation optical system. That is, the image and the index are displayed using the same display means and observation optical system. Further, the light source for illuminating the image and the index, and the first optical pupil and the second optical pupil are substantially conjugate. Therefore, the first optical pupil and the second optical pupil can be matched, and it is confirmed whether or not the image can be observed and whether or not the image is displayed without the optical pupil being displaced from the eye by the index. it can. Moreover, a bright image can be observed, and whether or not the image can be observed and whether or not the image is displayed can be confirmed by a bright virtual image of the index.

  Further, the display area presenting means displays an index indicating the end of the display area. That is, since the edge of the screen is displayed, even if the screen center is set as the center of the observer's visual field, the visual field is hardly obstructed and the video can be easily observed.

  In addition, the display area presenting means can display the index by an index display unit different from the display means. Therefore, the display area of the video displayed on the display means is wide, and more information is displayed.

  Further, the indicator display unit displays the indicator outside the display area. Therefore, it is possible to confirm whether the video can be observed and whether the video is displayed without hindering the video observation.

  The indicator display unit displays the indicator in green. In other words, since the indicator is displayed in green with high visibility, visibility can be improved while reducing power consumption, and it is confirmed whether or not the image can be observed and whether or not the image is displayed. it can.

  Further, the index display unit displays an index having a luminance higher than the maximum luminance of the video. That is, since the display area presenting means can display the index by an index display unit different from the display means, it is possible to display an index with a brightness higher than the maximum brightness of the video displayed on the display means. Therefore, it is easy to find the display area by the high brightness index, and it is difficult to lose sight. Thereby, it can be confirmed reliably whether it is in the state which can observe an image | video, and the display presence or absence of an image.

  In addition, the distance between the virtual image of the image and the virtual image of the index was set to be 1 diopter or less. In other words, since the distance between the virtual images of the video and the index is reduced, the observer can easily observe the two virtual images without feeling a burden.

  Further, the display area presenting means displays the indicator when the luminance of the video is below a predetermined level. In other words, since the index is displayed when the video is dark, it is possible to check whether the video can be observed and whether or not the video is displayed even when the luminance of the outside world is higher than the luminance of the video. . In addition, the operation of the apparatus can be confirmed.

  The display area presenting means displays the indicator when the main power of the video display device is turned on. In other words, when the observer is using the device, the indicator is always displayed, so whether or not the image can be observed and whether or not the image is displayed even when the image is dark or not displayed. Can be confirmed. In addition, since the operation of the apparatus can be checked, it can be used in a state where it is always mounted.

  Further, the display area presenting means displays an indicator having a luminance higher than half of the maximum luminance of the video. Therefore, it is possible to reliably check whether or not the image can be observed and whether or not the image is displayed by using the high brightness index.

  The observation optical system uses a volume phase type reflection hologram optical element with a narrow diffraction efficiency half width. Therefore, it is possible to observe a bright external scene with high external light transmittance. Moreover, since the diffraction efficiency is high, a bright image can be observed.

  In addition, the half-value width of the diffraction efficiency of the reflection hologram optical element was set to be 5 nm or more and 10 nm or less in terms of wavelength. Therefore, it is possible to observe a bright external scene with high external light transmittance. Moreover, since the diffraction efficiency is high, a bright image can be observed.

  The reflection hologram optical element has positive optical power that is axisymmetric. Therefore, the degree of freedom of arrangement of the optical system is high, and the apparatus can be reduced in size and weight.

  In addition, the observation optical system has a first transparent substrate capable of totally reflecting the image light and the index light and transmitting through the outside scene. That is, since the first transparent substrate that totally reflects the image light and the index light is provided, the external light has a high transmittance, and a bright external scene can be observed with a wide field of view. In addition, the apparatus can be reduced in size and weight.

  Further, the observation optical system can cancel the refraction of light by the inclined surface supporting the reflection hologram optical element formed on the lower end portion of the first transparent substrate and can observe through the external scene. A second transparent substrate was provided. That is, since the light refraction by the inclined surface formed at the lower end portion of the first transparent substrate is canceled by the second transparent substrate, a bright external scene without distortion can be observed with a wide field of view.

  The light source for illuminating the image and the index is an LED, and the intensity peak wavelength of the LED is set to be substantially equal to the diffraction peak wavelength of the reflection hologram optical element. Therefore, it is easy to see and a bright image can be observed.

  In addition, since the video display device can be worn on the head, it is possible to observe a bright image while wearing it at all times without feeling the burden like glasses, and at the same time, the outside scene can be viewed with a wide field of view through the observation optical system. It can be observed beautifully.

  Embodiments of a video display apparatus according to the present invention will be described below with reference to the drawings. In addition, although this invention is demonstrated based on embodiment of illustration, this invention is not limited to this embodiment.

[Embodiment 1]
First, the configuration of the video display apparatus 10 according to the first embodiment will be described with reference to FIG. FIG. 1 is a side sectional view from the left side of the video display device 10 and mainly shows the internal configuration of the video display device 10.

  As shown in FIG. 1, the video display device 10 includes a housing 119, an LED (Light Emitting Diode) 112, a lens 113, a diffusion plate 114, and an LCD (Liquid Crystal Display) 111, and corresponds to the display means in the present invention. A display unit 110, transparent substrates 102 and 103, an observation optical system 100 including a holographic optical element (HOE) 104, and the like are included. The video display device 10 guides the video displayed on the display unit 110 to the eyeball M of the observer as a virtual image via the observation optical system 100. Furthermore, light incident from the front is guided to the eyeball M of the observer through the observation optical system 100. As a result, the observer can see-through the external scene (front subject), and observes the video superimposed on the external scene.

  With the LED 112, the lens 113, the diffuser plate 114, and the LCD 111 built in the housing 119 of the display unit 110, the housing 119 is diagonally upward and forward at the upper end of the transparent substrate 102 of the observation optical system 100. It is attached in such a manner as to protrude in the diagonally upward direction in FIG.

  The LED 112 corresponds to a light source in the present invention, and is a point light source in which three colors of R (red light), G (green light), and B (blue light) are integrated.

  The lens 113 collects the light from the LED 112 and projects it onto the LCD 111.

  The diffusing plate 114 is a unidirectional diffusing plate having different diffusivities depending on directions.

  The LCD 111 is a video generated based on a content video signal such as a DVD or a video captured from an external I / F (not shown), and modulates the light from the LED 112 to display the video. It is a transmissive liquid crystal display panel provided with a wavelength limiting filter.

  The transparent substrate 102 corresponds to the first transparent substrate in the present invention, is a substantially plate-like transparent member made of glass, transparent resin, or the like, and causes light from the LCD 111 to be reflected a plurality of times inside. . The upper end of the transparent substrate 102 has a wedge shape so that the front side (opposite side of the eyepiece surface) protrudes to be thicker upward so that most of the light from the LCD 111 can be collected inside. The formed thick part 102a is formed.

  In addition, an inclined surface 102d is formed at the lower end of the transparent substrate 102. The transparent substrate 102 has a HOE 104 attached to the inclined surface 103d formed on the transparent substrate 103 corresponding to the second transparent substrate in the present invention. Are joined (for example, bonded). Further, the front and back surfaces of the transparent substrate 102 are flush with the front and back surfaces of the transparent substrate 103. Thus, the transparent substrate 102 is integrated with the transparent substrate 103 in a single plate shape.

  The HOE 104 is a volume phase type holographic optical element having a positive power, which is configured by a so-called free-form surface which is optically asymmetric with respect to the axis, and is supported at a lower end portion of the transparent substrate 102 with a predetermined inclination angle. . The HOE 104 provides a hologram image to the eyeball M using the light interference phenomenon by being irradiated with the light guided by the transparent substrate 102.

  In the image display device 10 having the above-described configuration, the light emitted from the LED 112 illuminates the LCD 111 through the diffusion plate 114 and the lens 113, and the image light generated by the LCD 111 by this illumination is within the transparent substrate 102. After being subjected to total reflection several times on the front surface 102 c and the eyepiece surface 102 b, it is diffracted by the HOE 104 and guided to the optical pupil 109 as a virtual image by the positive power of the HOE 104. The image light guided to the optical pupil 109 enters the eyeball M, and the observer can observe the image.

  Further, the transparent substrate 102 guides light incident from the front to the eyeball M of the observer. As a result, the observer can see-through the external scene (front subject), and observes the video superimposed on the external scene.

  The inclined surface 103 d formed on the transparent substrate 103 cancels (cancels) light refraction at the inclined surface 102 d of the transparent substrate 102. That is, in order to prevent the light from the arrow W side from bending upward due to the prism effect on the inclined surface 102d, the observer observes the outside scene through the transparent substrate 102, the transparent substrate 103, and the HOE 104 without distortion. be able to.

  Further, since the HOE 104 is axially asymmetric, the degree of freedom of arrangement of the optical system is high, the observation optical system 100 can be miniaturized, and a high-quality image can be provided.

  Further, the observer can observe the external scene through the transparent substrates 102 and 103 and the HOE 104 within a range wider than the size of the optical pupil 109 that can observe the image light. That is, an external scene with a wide field of view can be observed through the transparent substrates 102 and 103 and the HOE 104 at the position of the optical pupil 109.

  In addition, since the image light from the LCD 111 is reflected in the transparent substrate 102 and guided to the eyeball M, the transparent substrate 102 can be configured to be as thin (for example, about 3 mm) as a normal eyeglass lens, and is small and lightweight. It becomes. Further, since the reflection in the transparent substrate 102 is total reflection, the observer observes a bright outside scene through the front surface 102c and the eyepiece surface 102d of the transparent substrate 102 with a wide field of view without reducing the transmittance of outside light. be able to.

  Next, details of the optical system of the video display device 10 will be described. The XYZ coordinate axes will be described as directions shown in FIG.

  The lens 113 and the HOE 104 are arranged so that the LED 112 and the optical pupil 109 are conjugated, and the diffusion plate 114 diffuses the light of the LED 112 collected by the lens 113 by 40 degrees in the X direction and in the Y direction. Diffuse 0.5 degrees. Therefore, the lens 113 condenses the light of the LED 112, and the light diffused by the diffusion plate 114 efficiently forms the optical pupil 109, and a bright image can be observed.

  The optical pupil 109 is set to have a half intensity value of 6 mm in the X direction and 2 mm in the Y direction.

  In the X direction, since the diffusion is performed by the diffusion plate 114, the conjugate relationship between the LED 112 and the optical pupil 109 is not established. However, the conjugate arrangement allows the light of the LED 112 to be used with high efficiency and enables bright display.

  In the video display device 10 according to the first embodiment, the LED 112 and the optical pupil 109 are arranged so as to be conjugated. In this case, the optical pupil 109 is limited by the size of the HOE 104, and an optical pupil 109 that is slightly smaller than the HOE 104 is formed.

  Next, the intensity characteristics of the LED 112 will be described with reference to FIG. FIG. 3 is a diagram illustrating the intensity characteristics of the LED 112.

  As shown in FIG. 3, the LED 112 uses R, G, B integrated LEDs (manufactured by Nichia Chemical Co., Ltd.) having center wavelengths of 462 nm ± 12 nm, 525 nm ± 17 nm, and 635 nm ± 10 nm, respectively. The LED 112 adjusts the intensity in consideration of the diffraction efficiency of the HOE 104 and the transmittance of the LCD 111 to enable white display.

  Next, the diffraction efficiency characteristics of the HOE 104 will be described with reference to FIG. FIG. 4 is a diagram showing the diffraction efficiency characteristics of the HOE 104.

  As shown in FIG. 4, the HOE 104 is fabricated so as to diffract image light having wavelengths of 465 nm ± 5 nm, 521 nm ± 5 nm, and 634 nm ± 5 nm at half the diffraction efficiency. Since the half width of diffraction efficiency is narrow, the external light has a high transmittance and a bright external scene can be observed. Moreover, since the diffraction efficiency is high, a bright image can be observed.

  Thus, since the diffraction peak wavelength of the HOE 104 and the intensity peak wavelength of the LED 112 are close, a bright image can be displayed.

  In addition, since the HOE 104 is manufactured so as to diffract only light having a specific incident angle and a specific wavelength, it can be transmitted with little influence on external light. Therefore, the observer can observe the outside scene as usual through the transparent substrate 102 and the HOE 104.

  In the video display device 10 having such a configuration, the present invention displays an index indicating the video display area, so that the optical pupil 109 is displaced from the eyeball M by the index even when the video is dark or not displayed. Therefore, it is possible to easily confirm whether or not the image can be observed and whether or not the image is displayed, and to prevent losing sight of the position where the image is displayed. In addition, since the position where the image is displayed by the index is not lost, the optical pupil 109 can be made small, a bright image can be observed while reducing the size and weight of the apparatus, and the outside scene can be widened through the observation optical system 100. It makes it possible to observe clearly in the field of view.

  Here, the index display indicating the video display area will be described with reference to FIG. FIG. 2A is a side sectional view from the left side surface of the video display device 10, and mainly shows the internal configuration of the video display device 10. FIG. 2B shows an image displayed on the LCD 111 and an index. FIG. 2C is a schematic diagram illustrating an example of an image guided to the optical pupil 109 and a virtual image of an index.

  As shown in FIG. 2B, the LCD 111 displays the video B and the index C indicating the area where the video is displayed in the display area A of the screen. The indicator C indicates the four corners of the display area A.

  As shown in FIG. 2C, the LCD 111 is guided to the optical pupil 109 through the observation optical system 100 as the virtual image G, and the video B and the index C displayed on the LCD 111 are respectively virtual images b and c. . The virtual images b and c guided to the optical pupil 109 enter the eyeball M and are observed by an observer. That is, the optical pupil 109 corresponds to the first optical pupil and the second optical pupil in the present invention. Further, the display unit 110 and the observation optical system 100 also function as display area presenting means in the present invention.

  In this way, the observer can visually recognize the four corners of the display area a on which the video is displayed as the index c (virtual image of the index C), and thus can observe the video b (virtual image of the video B). It is possible to observe an external scene while easily confirming whether or not the image b is displayed.

Note that the brightness of the index c is set to 200 Cd / m ² which is half of the maximum brightness (eg, 400 Cd / m ² ) of the video b. Therefore, even when the video b is dark or not displayed, it is possible to easily check whether or not the video b can be observed and whether or not the video b is displayed, and the video b is not lost. Also, the operation can be confirmed.

In addition, since the brightness of the index c (virtual image of the index C) is about 1/10 with respect to the background brightness, the brightness of the index c may be set to 100 Cd / m ² or more. As a result, the index c can be recognized outdoors even at about 1000 Cd / m ^{2 and} can be used in a wide range.

  Next, as shown in FIG. 2A, D indicates the size of the optical pupil 109, and E indicates the range in which the observer can observe the outside scene through the transparent substrates 102 and 103 and the HOE 104. F indicates the viewing angle of the outside world at the optical pupil 109, and the viewing angle F increases as E increases.

  By reducing the size D of the optical pupil 109 to 10 mm or less, a bright image b can be observed while miniaturizing the apparatus. Further, by setting the range E in which the outside scene can be observed to a wide range of 10 mm or more, the outside viewing angle F observed at the position of the optical pupil 109 can be increased. That is, the image b of the small optical pupil 109 is observed in a state where the external scene can be observed in a wide range. On the other hand, since the transparent substrates 102 and 103 and the HOE 104 have a high transmittance of 85% or more, the position of the optical pupil 109 is difficult to understand. However, the index c indicating the display area a allows the observer to easily confirm whether or not the video b can be observed and whether or not the video b is displayed, and the video b is not lost.

  In the video display device 10 according to the first embodiment, the index c indicating the display area a of the video b is always displayed when the main power of the video display device 10 is turned on. Therefore, for example, it is possible to prevent the optical pupil 109 from coming off the observer's eyeball M when the image b is not displayed. Thereby, even if the image b changes from the non-display state to the display state, the image b is not lost.

  Further, in the video display device 10 according to the first embodiment, the index c indicates the four corners of the display area a. For example, as shown in FIG. 5A, the video display area a can be confirmed. Similarly, it is good also as a form which shows the screen edge perimeter c of LCD111. Since the entire periphery of the display area a can be confirmed, it is possible to confirm whether or not the image can be observed and whether or not the image is displayed. Moreover, since there are few indications that obstruct the external field of view, it is easy to see the external scene.

  Further, as shown in FIG. 5B, only the screen center c of the LCD 111 may be shown so that the video display area a can be confirmed. By using a small index indicating only the screen center c, the number of displays that obstruct the external field of view is reduced, making it easier to see the external scene.

[Embodiment 2]
Next, the video display device 20 according to the second embodiment will be described. The configuration of the main part is substantially the same as that of the video display device 10 according to the first embodiment described above, and a detailed description thereof will be omitted. An index display unit having a configuration different from that of the video display device 10 will be described. In the video display device 10, the index is also displayed on the LCD 111 that displays the video. However, the video display device 20 includes an index display unit that is different from the LCD and displays the index.

  First, the configuration of the video display device 20 according to the second embodiment will be described with reference to FIG. FIG. 6A is a side sectional view from the left side of the video display device 20, and mainly shows the internal configuration of the video display device 20. FIG. 6B is a schematic diagram illustrating an example of a virtual image of an index guided to the optical pupil 209.

  As shown in FIG. 6A, the video display device 20 includes a housing 219, an LED 212, a lens 213, and an LCD 211, and an observation unit 210 that corresponds to the display means in the present invention, a transparent substrate 202, and an HOE 204. It has the optical system 200, LED215 etc. which correspond to the parameter | index display part in this invention. In the video display device 20 according to the second embodiment, the LED 215 and the observation optical system 200 function as display area presenting means in the present invention.

  In the video display device 20 having such a configuration, the light emitted from the LED 212 illuminates the LCD 211 through the lens 213, and the video light generated by the LCD 211 by this illumination is diffracted by the HOE 204, and the positive light of the HOE 204 It is guided to the optical pupil 209 as a virtual image by power. The image light guided to the optical pupil 209 enters the eyeball M, and the observer can observe the image.

  Further, the transparent substrate 202 guides light incident from the front to the eyeball M of the observer. As a result, the observer can see-through the external scene (front subject), and observes the video superimposed on the external scene.

  Further, the lens 213 and the HOE 204 are arranged so that the LED 212 and the optical pupil 209 are conjugated so that the light efficiently forms the optical pupil 209.

  The LED 212 corresponds to the light source in the present invention, and is a white LED that excites a phosphor with blue light or violet light. By using a white LED, it is not necessary to mix three colors of R (red light), G (green light), and B (blue light), so that the LED 112 and the optical pupil 209 can be conjugated and brightened.

  The LED 215 is a green LED having a wavelength of 520 nm for displaying an index indicating a display area of an image. Since the LED 215 is arranged outside the LCD 211 as shown in FIG. 6A, it is observed as a virtual image c outside the display area a as shown in FIG. 6B. Since the index c is observed outside the display area a, it is difficult to disturb the external field of view and does not disturb the image.

  In addition, the LED 215 is disposed outside the vicinity of the LCD 211 so that the distance between the virtual image c and the virtual image G of the video is reduced. For example, the virtual image G of the video is −1 diopter, and the virtual image c of the LED 215 is −1.5 diopter. That is, since the distance between the virtual image c of the LED 215 and the virtual image G of the video is set to 1 diopter or less, the observer can easily observe the two virtual images without getting tired.

  In addition, since the index is displayed on the index display unit (LED 215) different from the display unit 210 that displays the video, the index can be displayed with higher brightness than the video. Therefore, it is easy to find the display area by the high brightness index, and it is difficult to lose sight. Thereby, even when the video is dark or not displayed, it is possible to reliably check whether or not the video can be observed and whether or not the video is displayed.

  Further, since the LED 212 and the optical pupil 209 are arranged so as to have a substantially conjugate relationship, the optical pupil 209 has an LED 212 light emitting unit size x = 3 mm, y = 0.5 mm, and the image magnification of the optical system is 3 times. Furthermore, the size is set to be a little larger by diffusion of about 1 degree of the LCD 211, and the size is set to x = 10 mm and y = 2.5 mm. In this manner, the optical pupil 209 is set to 10 mm larger than the human pupil (about 3 mm) in the X direction, so that it is easy to observe with a large optical pupil and is almost the same as the human pupil in the Y direction. Since it is set to about 2.5 mm, it is possible to efficiently collect light and observe a bright image.

  In the video display device 20 according to the second embodiment, the index c indicating the video display area a is displayed only when the luminance of the video is below a predetermined level. When the video is bright, it is possible to check whether the video can be observed and whether the video is displayed. Therefore, by displaying and confirming the index c only when the image is dark or not displayed, it is possible to suppress power consumption and not to disturb the observation of the outside scene and the image. Further, the display of the index c may be selected by an observer's operation.

[Embodiment 3]
Next, the video display device 30 according to the third embodiment will be described. The configuration of the main part is substantially the same as that of the video display device 10 according to the first embodiment described above, and a detailed description thereof will be omitted. An LCD having a configuration different from that of the video display device 10 will be described. In the video display device 10, a transmissive LCD provided with a wavelength limiting filter is used, but in the video display device 30, a reflective LCD without a color filter is used.

  First, the configuration of the video display device 30 according to the third embodiment will be described with reference to FIG. FIG. 7 is a side sectional view from the left side of the video display device 30, and mainly shows the internal configuration of the video display device 30.

  As shown in FIG. 6A, the video display device 30 includes a housing 319, an LED 312, a cylindrical mirror 313, a diffusion plate 314, a polarizing plate 315, a polarizer 316, an analyzer 317, and a liquid crystal 311. A display unit 310 corresponding to a display unit, an observation optical system 300 including transparent substrates 302 and 303, and an HOE 304 are included.

  In the video display device 30 having such a configuration, the light emitted from the LED 312 is reflected by the cylindrical mirror 313 to illuminate the liquid crystal 311, and the video light generated by the liquid crystal 311 by this illumination is transmitted in the transparent substrate 302. After being subjected to total reflection several times on the front surface 302c and the eyepiece surface 302b, the light is diffracted by the HOE 304 and guided to the optical pupil 309 as a virtual image by the positive power of the HOE 304. The image light guided to the optical pupil 309 enters the eyeball M, and the observer can observe the image.

  Further, the transparent substrate 302 guides light incident from the front to the eyeball M of the observer. As a result, the observer can see-through the external scene (front subject), and observes the video superimposed on the external scene.

  The reflective LCD includes a liquid crystal 311 held between a polarizer 316 and a substrate, an analyzer 317, and the like, and is based on a content video signal such as a DVD or a video captured from an external I / F (not shown). With the generated video, the light from the LED 312 is modulated to display the video.

  The LED 312 corresponds to the light source in the present invention, and is a point light source in which three colors of R (red light), G (green light), and B (blue light) are integrated.

  The cylindrical mirror 313 collects the light from the LED 312 only in a direction parallel to the YZ plane.

  The diffusion plate 314 is a unidirectional diffusion plate having different diffusivities in the X direction and the Y direction.

  The polarizing plate 315 transmits polarized light in the same direction as the polarizer 316, and unnecessary light that is not modulated by the reflective LCD, such as direct light from the LED 312 or surface reflection by the polarizer 316, is absorbed by the analyzer 317. It is prevented from being guided to M.

  In the video display device 30 according to the third embodiment, the reflective LCD does not include a color filter, but the LED 312 is an image generated by the reflective LCD by driving the R, G, and B light sources of the LED 312 in a time-sharing manner. Color display is possible by modulating the light from Further, since no color filter is provided, the transmittance is high, R, G, and B are displayed in the same pixel, and an electric circuit for driving the pixel is disposed on the back surface of the display surface, so that a high aperture ratio and a bright image can be obtained. Can be displayed.

  Further, the LED 312 and the optical pupil 309 are arranged in a conjugate manner in the Y direction. On the other hand, as described above, the reflective LCD has a high aperture ratio and thus has a small diffusion. Therefore, the LED 312 and the optical pupil 309 are substantially conjugate in the Y direction. Since the cylindrical mirror 313 does not have power in the X direction, it is not conjugate.

  As described above, according to the video display device of the present invention, the display area presenting means displays the index indicating the display area of the video displayed on the display means. Therefore, even when the image is dark or not displayed, it is possible to easily check whether the image can be observed and whether or not the image is displayed without the optical pupil being displaced from the eye by the index, and the image is displayed. Do not lose sight of the location. In addition, the operation of the apparatus can be confirmed. In addition, the first optical pupil is smaller than the range in which the external scene of the observation optical system can be observed, and the size and position of the second optical pupil are substantially matched. That is, the optical pupil can be reduced because the position where the image is displayed is not lost due to the index. Therefore, the apparatus can be reduced in size and weight, and a bright image can be observed, and at the same time, the outside scene can be clearly observed with a wide field of view through the observation optical system.

  Next, an embodiment of a head mounted video display device (HMD) provided with the video display device according to the present invention will be described with reference to FIG. Fig.8 (a) is a top view of HMD1 which concerns on this invention, FIG.8 (b) is a front view.

  The HMD 1 is a head-mounted video display device that is used in the vicinity of an observer's eyeball. As shown in FIG. 1A, the HMD 1 includes frames 400R and 400L, a bridge 500, nose pads 500R and 500L, temples 600R and 600L, a cable 700, a video display device 10, and the like. As described above, the video display device 10 guides the video displayed on the display unit 110 to the eyeball M of the observer through the observation optical system 100 as a virtual image. Furthermore, light incident from the front is guided to the eyeball M of the observer through the observation optical system 100. As a result, the observer can see-through the external scene (front subject), and observes the video superimposed on the external scene.

  The temples 600R and 600L are provided as a pair on the left and right sides of the frames 400R and 400L, and are long members made of a flexible elastic material or the like. This is for holding the head of the HMD 1 on the observer and adjusting the mounting position. The temples 600R and 600L are configured to be rotatable in the directions of arrows P and Q in the rotating portions 600Ra and 600La. When the HMD 1 is not used, the temples 600R and 600L are rotated in the directions of the arrows P and Q. It can be made compact by moving it along the frames 400R and 400L.

  The bridge 500 includes nose pads 500R and 500L that hold the HMD 1 on the face of the observer, and is a short rod-like member that spans a predetermined position facing the transparent substrate 102 and the frame 400L. And the frame 400L are held in a relative positional relationship with a certain gap therebetween.

  The cable 700 supplies power, a video signal, a control signal, and the like to the video display device 10.

  As described above, according to the head image display device according to the present invention, the observer can hold the HMD 1 in front of the eyes like the normal glasses by the nose pads 500R and 500L and the temples 600R and 600L. Accordingly, it is possible to observe a bright image while wearing it at all times without feeling a burden as in the case of glasses, and at the same time, it is possible to clearly observe an external scene with a wide field of view through an observation optical system. Further, by providing the ND filter 800 on the front surface of the transparent substrate 102, it is possible to make the image easy to see by reducing the transmittance of the external light, or to make the external scene easy to see by setting the transmittance to 50% or more.

  Although one HMD 1 according to the present embodiment is provided corresponding to only one eyeball, one HMD 1 may be provided corresponding to both eyes as shown in FIG. At this time, even if the indicator is displayed only on one eyeball, it can be easily confirmed whether or not the image can be observed and whether or not the image is displayed. Therefore, only one display area presenting means is provided. May be.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be changed or improved as appropriate. For example, the transparent substrate according to the above-described embodiment uses a planar plate-like member, but may be formed in a shape having a curvature. Thereby, it can serve as a correction | amendment spectacles lens.

It is a sectional side view which shows the structure by Embodiment 1 of the video display apparatus based on this invention. 6 is a schematic diagram illustrating an example of index display according to Embodiment 1. FIG. It is a figure which shows the intensity | strength characteristic of LED in Embodiment 1. FIG. It is a figure which shows the diffraction efficiency characteristic of HOE in Embodiment 1. It is a schematic diagram by another example showing the indicator display in the first embodiment. It is a sectional side view which shows the structure by Embodiment 2 of the video display apparatus based on this invention. It is a sectional side view which shows the structure by Embodiment 3 of the video display apparatus based on this invention. It is an external view by an example of HMD which concerns on this invention. It is an external view by another example of HMD concerning the present invention.

Explanation of symbols

1 HMD
10, 20, 30 Video display device 100, 200, 300 Observation optical system 102, 103, 202, 302, 303 Transparent substrate 104, 204, 304 HOE
109, 209, 309 Optical pupil 110, 210, 310 Display unit 111, 211 LCD
112, 212, 312 LED (light source)
113, 213 Lens 114, 314 Diffusion plate 119, 219, 319 Case 206 Support member 215 LED (index display unit)
311 Liquid crystal 313 Cylindrical mirror 315 Polarizing plate 316 Polarizer 317 Analyzer 400R, 400L Frame 500 Bridge 500R, 500L Nose pad 600R, 600L Temple 700 Cable 800 ND filter

Claims (19)

Display means for displaying video;
The image light from the display means is projected onto the observer's eyeball to form a first optical pupil that guides the image to the eyeball as a virtual image, and the image by the first optical pupil is superimposed on an external scene. An observation optical system that can be
Display area displaying means for displaying an index indicating a display area of an image displayed on the display means, and forming a second optical pupil that guides the index to the eyeball as a virtual image,
The first optical pupil is smaller than a range in which an external scene of the observation optical system can be observed, and the size and position of the second optical pupil substantially coincide with each other. The first optical pupil and the second optical pupil are 1 mm or more and 10 mm or less, and a range in which an external scene of the observation optical system can be observed is 10 mm or more and 50 mm or less. Video display device. The display area presenting means comprises the display means and the observation optical system,
The display means includes a light source that displays the video and the index, and illuminates the video and the index,
The observation optical system forms the first optical pupil and the second optical pupil that guide the image and the index to the eyeball as virtual images,
The video display device according to claim 1, wherein the light source, the first optical pupil, and the second optical pupil are substantially conjugate. The video display device according to claim 1, wherein the display area presenting unit displays an index indicating an end of the display area. The video display apparatus according to claim 1, wherein the display area presenting unit includes an index display unit that displays the index. The video display apparatus according to claim 5, wherein the index display unit displays the index outside the display area. The video display device according to claim 5, wherein the index display unit displays the index in green. The video display device according to claim 5, wherein the index display unit displays the index having a luminance higher than a maximum luminance of the video. 9. The video display device according to claim 5, wherein a distance between the virtual image of the index and the virtual image of the video is 1 diopter or less. The video display apparatus according to claim 1, wherein the display area presenting unit displays the index when the luminance of the video is equal to or lower than a predetermined level. 6. The video display device according to claim 1, wherein the display area presenting means displays the index when the main power of the video display device is turned on. The video display device according to claim 1, wherein the display area presenting unit displays the index having a luminance higher than half of the maximum luminance of the video. The observation optical system includes a volume phase type reflection hologram optical element,
The image light from the display means is reflected by the reflection hologram optical element and projected onto an observer's eyeball to form a first optical pupil that guides the image as a virtual image to the eyeball, and the first optical The video display device according to claim 1, wherein the video by the pupil is displayed so as to be superimposed on an external scene. The video display device according to claim 13, wherein the half width of the diffraction efficiency of the reflection hologram optical element is 5 nm to 10 nm in wavelength. 15. The video display device according to claim 13, wherein the reflection hologram optical element has an axially asymmetric positive optical power. The said observation optical system has the 1st transparent substrate which can reflect and observe the external scene by totally reflecting the said image light and parameter | index light, It is characterized by the above-mentioned. Video display device. An inclined surface that supports the reflection hologram optical element is formed at the lower end of the first transparent substrate,
17. The image according to claim 16, wherein the observation optical system includes a second transparent substrate that cancels light refraction by the inclined surface and can be observed through an external scene. Display device. The light source is an LED;
14. The image display device according to claim 13, wherein the intensity peak wavelength of the LED is substantially equal to the diffraction peak wavelength of the reflection hologram optical element. A head-mounted image display device comprising the image display device according to claim 1.

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