JP2009145513A - Video display apparatus and head mount display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent, by a simple configuration, a wavefront of video light from being disturbed by external foreign matter P; and to avoid degradation in the quality of a video to be observed, caused by foreign matter P. <P>SOLUTION: The video display apparatus is provided with a protective substrate 32 for protecting the face 21b of an eyepiece prism 21, and a support member 33 for supporting the protective substrate 32. The protective substrate 32 is disposed via the face 21b of the eyepiece prism 21 and an air layer. This ensures the occurrence of a refractive index difference between two media sandwiching the face 21b. Thus, the protective substrate 32 prevents external foreign matter P from directly sticking to the surface 21b. Accordingly, video light guided inside the eyepiece prism 21 is surely and totally reflected by the face 21b, thereby preventing the wavefront of the video light from being disturbed by the foreign matter. Moreover, the support member 33 supports the protective substrate 32 in contact with the non-total reflection area 21b<SB>2</SB>of the face 21b. This prevents the support member 33 from interfering with the total reflection of video light in the total reflection area 21b<SB>1</SB>of the face 21b. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an image display device that provides an observer with an image displayed on a display element as a virtual image, and a head mounted display (hereinafter also referred to as an HMD) including the image display device.

  Various so-called see-through HMDs have been conventionally proposed in which image light from a display element and external image light (external light) are simultaneously guided to an observer's pupil through an eyepiece optical system. In particular, in the HMD of Patent Document 1, a light reducing film made of, for example, a multilayer film is provided on the surface of a substrate constituting an eyepiece optical system, and image light guided by total reflection inside the substrate by the light reducing film. The external light is diminished without increasing the light loss, and the visibility of the display image when the outside is bright is improved.

JP 2006-162767 A

  By the way, for example, when an HMD is used outdoors under bad weather such as rain, if water droplets (raindrops) adhere to the substrate surface of the eyepiece optical system, the image light guided through the substrate transmits through the substrate surface. Then, the light is incident on the water droplet, and then is reflected at the interface between the water droplet and the air layer and enters the inside of the substrate again, or passes through the water droplet and is emitted to the outside. In any case, the image light guided through the substrate deviates from the normal optical path at the time of total reflection at the interface between the substrate and the air layer due to the water droplets. For this reason, the quality of the image observed by the observer is lowered. Further, for example, even when a finger touches the substrate surface of the eyepiece optical system, the optical path of the image light is disturbed due to the oil content of the finger adhering to the substrate surface. Therefore, it is necessary to take some measures so that the wavefront of the image light guided through the inside of the substrate is not disturbed due to an external foreign material adhering to the substrate surface of the eyepiece optical system.

  In this regard, in Patent Document 1, since the light loss of the image light is reduced by the dimming film on the substrate surface, it is considered that the wave front of the image light can be prevented to some extent from the adhesion of external foreign matters. It is. However, in order to construct such a dimming film (multilayer film), the material constituting the multilayer film, the layer thickness of each layer, the refractive index of each layer, the number of layers, etc. must be appropriately controlled. It is difficult to construct a light reducing film having the above characteristics. Therefore, it is desired to prevent the disturbance of the wavefront of the image light caused by the external foreign matter with a simpler configuration.

  The present invention has been made to solve the above-described problems, and the object thereof is to prevent the wavefront of the image light from being disturbed due to an external foreign object with a simple configuration. Accordingly, the present invention is to provide a video display device capable of avoiding degradation of the quality of the observed video due to the foreign matter, and an HMD including the video display device.

  An image display apparatus according to the present invention is an image display apparatus including a display element that displays an image, and an eyepiece optical system that includes a light guide member that guides image light from the display element to an optical pupil. The light guide member has a total reflection surface including a region that totally reflects the image light from the display element, and a reflection surface that reflects the image light totally reflected by the total reflection surface and guides it to the optical pupil. The image display device further includes protection means for protecting the total reflection surface. The protection means includes a protection substrate disposed via the total reflection surface and the air layer, and image light on the total reflection surface. And a support member that supports the protective substrate in contact with a region where the light is not totally reflected.

  According to the above configuration, the image light from the display element is guided through the light guide member of the eyepiece optical system, totally reflected by the total reflection surface (particularly, the total reflection region), and then reflected by the reflection surface. To the optical pupil. Therefore, at the position of the optical pupil, the observer can observe the virtual image of the display image on the display element.

  In addition, since the protective substrate of the protective means for protecting the total reflection surface is disposed via the total reflection surface and the air layer, the refractive index difference between the two media sandwiching the total reflection surface is reliably generated, It is possible to prevent the foreign matter (for example, water droplets such as raindrops and oil droplets such as hand oil) from directly adhering to the total reflection surface with the protective substrate. Therefore, the image light guided inside the light guide member is reliably totally reflected by the total reflection surface, and the wave front of the image light is not disturbed due to the foreign matter. As a result, it is possible to avoid deterioration of the quality of the observed display image due to the foreign matter with a simple configuration in which the protective substrate is arranged via the total reflection surface and the air layer.

  In addition, since the protective substrate is supported by a support member that is in contact with the total reflection surface, the thickness of the air layer, that is, the total reflection is obtained while the air layer is reliably interposed between the total reflection surface and the protection substrate. It is easy to minimize the distance between the surface and the protective substrate. As a result, the above-described effects of the present invention can be obtained while easily downsizing the apparatus. In addition, since the support member is in contact with a region on the total reflection surface where the image light is not totally reflected, the support member does not prevent the total reflection of the image light on the total reflection surface, and reliably reflects the image light. be able to.

  In the video display device of the present invention, the light guide member may be configured to transmit external light. In this case, the observer can observe the outside world image see-through while observing the virtual image of the display image of the display element.

  In the video display device of the present invention, the protective substrate may be transparent. If the protective substrate is transparent in the configuration in which the light guide member transmits external light, observation of the external image is not hindered by the protective substrate.

  In the video display device of the present invention, it is desirable that the eyepiece optical system further includes a correction member that is joined via the reflection surface of the light guide member and cancels refraction of external light at the light guide member. . In this case, since the refraction of the external light at the light guide member is canceled by the correction member, it is possible to prevent distortion of the external image observed by the observer.

  In the video display device of the present invention, the support member is further in contact with the peripheral portion of the surface on the protective substrate side of the correction member such that the protective substrate faces both the light guide member and the correction member via the air layer. It is desirable to support the protective substrate. In this case, since the position of the ridgeline of the support member is away from the axis passing through the center of the optical pupil (because it is away from the center of the visual field), it is difficult for the observer to visually recognize the ridgeline even when observing the external field image. The image can be observed well.

  In the image display device of the present invention, the total reflection surface is configured by a first surface on the opposite side of the optical pupil in the light guide member and a second surface on the optical pupil side, and the protection means includes It may be provided corresponding to the first surface and the second surface.

  Since the protective means is provided corresponding to the first surface and the second surface constituting the total reflection surface of the light guide member, it is possible to prevent the external foreign matter from directly attaching to both surfaces of the light guide member. It is possible to reliably prevent the disturbance of the wave front of the image light.

  In the video display device of the present invention, the protective substrate may have optical power. In this case, the protection means can be provided with both the function of preventing the deterioration of the image quality caused by the external foreign matter and the function of correcting the diopter of the observer.

  In the video display device of the present invention, the protective substrate may be detachably supported by the support member. In this case, it is possible to use a protective substrate having an optical power corresponding to the observer to be used, and diopter correction corresponding to the observer to be used is possible.

  An image display apparatus according to the present invention is an image display apparatus including a display element that displays an image, and an eyepiece optical system that includes a light guide member that guides image light from the display element to an optical pupil. The light guide member has a total reflection surface that totally reflects the image light from the display element, and a reflection surface that reflects the image light totally reflected by the total reflection surface and guides it to the optical pupil. The video display device further includes a protection unit that protects the total reflection surface, and the protection unit includes a transparent water-repellent film having water repellency that is coated on the total reflection surface. It is said.

  According to the above configuration, the image light from the display element is guided inside the light guide member of the eyepiece optical system, totally reflected by the total reflection surface, then reflected by the reflection surface and guided to the optical pupil. . Therefore, at the position of the optical pupil, the observer can observe the virtual image of the display image on the display element.

  Further, since the protective means for protecting the total reflection surface has a water-repellent film coated on the total reflection surface, it is possible to prevent the disturbance of the wave front of the image light caused by external foreign matter. That is, if the external foreign matter is, for example, water droplets, the foreign matter can be prevented from directly adhering to the total reflection surface with the water-repellent film, and the water droplets can be made smaller and scattered by the water-repellent film. Therefore, the image light guided inside the light guide member is reliably totally reflected by the total reflection surface, and the wave front of the image light is not disturbed due to the water droplets. As a result, it is possible to avoid the deterioration of the quality of the display image to be observed due to the foreign matter with a simple configuration in which the water repellent film is coated on the total reflection surface. Further, since the water repellent film is transparent, for example, when the light guide member transmits external light, the observer can also observe the external image.

  In the video display device of the present invention, the light guide member may be configured to transmit external light. In this case, the observer can observe the outside world image see-through while observing the virtual image of the display image of the display element.

  In the video display device of the present invention, the protection means further includes a removable attachment member arranged via the light guide member and the air layer, and the surface of the attachment member on the light guide member side is hydrophilic. A hydrophilic film having properties may be coated.

  As the removable attachment member, for example, an attachment lens having optical power or a transflective plate for adjusting the transmittance of external light can be considered. Although an air layer is interposed between the light guide member and the attachment member, even if water drops such as raindrops enter the air layer, the foreign matter does not adhere to the light guide member side (water repellent). Because there is a film), it adheres to the attachment member side with the hydrophilic film. Therefore, it is possible to reliably prevent the wavefront of the image light from being disturbed due to the water droplets.

  In the video display device of the present invention, the protection means further includes a removable attachment member disposed via the light guide member and the air layer, and the surface of the attachment member on the light guide member side is repelled. A water-repellent water-repellent film may be coated.

  As the detachable attachment member, for example, an attachment lens having optical power or a transflective plate for adjusting the transmittance of external light can be considered as described above. Although an air layer is interposed between the light guide member and the attachment member, even if a water droplet such as raindrops enters the air layer, the water droplet does not adhere to both the light guide member and the attachment member. (Because each has a water-repellent film), it will fall. Therefore, it is possible to reliably prevent the wavefront of the image light from being disturbed due to the water droplets.

  In the video display device of the present invention, the eyepiece optical system may further include a correction member that is joined via the reflecting surface of the light guide member and cancels refraction of external light at the light guide member. In this case, since the refraction of the external light at the light guide member is canceled by the correction member, it is possible to prevent distortion of the external image observed by the observer.

  In the video display device of the present invention, the correction member has a surface located on the same plane as the total reflection surface of the light guide member, and the surface of the correction member is covered with a hydrophilic film. May be. In this case, since the water droplets repelled by the water repellent film on the total reflection surface of the light guide member are caught by the hydrophilic film coated on the surface of the correction member, the water droplet moves with the surface of the correction member. There is no such thing as a drop of water.

  In the video display device of the present invention, it is desirable that the light guide member includes a parallel plate. In this case, it is possible to reduce the size of the eyepiece optical system and thus the video display device by forming the light guide member thin.

  In the video display device of the present invention, the reflection surface of the light guide member is a surface on which a volume phase type reflection hologram optical element is formed. The hologram optical element diffracts and reflects the image light from the display element. A configuration may be adopted in which external light is transmitted to the optical pupil while being guided to the optical pupil. Since the volume phase type reflection type hologram optical element has a narrow reflection wavelength range and high external light transmittance, an observer can observe a bright external image through a see-through while observing a display image (virtual image). It becomes possible.

  In the video display device of the present invention, it is desirable that the hologram optical element has a positive optical power that is axially asymmetric. If the hologram optical element has axially asymmetric and positive optical power, the degree of freedom of arrangement of each optical member constituting the apparatus can be increased, and the apparatus can be easily downsized.

  The head-mounted display of the present invention includes the above-described video display device of the present invention and support means for supporting the video display device in front of an observer's eyes. In this configuration, since the video display device is supported by the support means, the observer can observe the video provided from the video display device stably in a hands-free manner for a long time.

  According to the present invention, the protective substrate and the support member are used to protect the total reflection surface, or the total reflection surface is protected by a water repellent film, thereby preventing external foreign matter from directly attaching to the total reflection surface. can do. Therefore, the image light guided inside the light guide member is reliably totally reflected by the total reflection surface, and the wave front of the image light is not disturbed due to the foreign matter. As a result, it is possible to avoid degradation of the quality of the observed display image due to the foreign matter with a simple configuration of the protection means.

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

(1. Configuration of HMD)
FIG. 2 is a perspective view showing a schematic configuration of the HMD according to the present embodiment. The HMD includes a video display device 1 and support means 2. In FIG. 2, for the sake of convenience, illustration of protection means described later is omitted.

  The video display device 1 has a housing 3 that includes at least a light source 11 and a display element 14 (both see FIG. 3). The housing 3 holds a part of the eyepiece optical system 4. The eyepiece optical system 4 is configured by bonding an eyepiece prism 21 and a deflection prism 22, which will be described later, and has a shape like one lens of a pair of glasses (lens for right eye in FIG. 2) as a whole. In addition, the video display device 1 is a circuit board (not shown) for supplying at least driving power and a video signal to the light source 11 and the display element 14 via a cable (not shown) provided through the housing 3. Z).

  The support means 2 corresponds to a frame of glasses, and supports the video display device 1 in front of the observer's eyes in a state of being in contact with the observer's temporal region. More specifically, the support unit 2 supports the eyepiece optical system 4 of the video display device 1 in front of one eye (for example, the right eye) of the observer, and supports the dummy lens 5 on the other eye (for example, the left side of the observer). Support in front of the eye). The support means 2 also includes left and right nose pads 6.

  When the observer wears the HMD on the head (the support means 2 is brought into contact with the observer's temporal head and the image display device 1 is positioned in front of the observer's eyes) and an image is displayed on the display element 14, The image light is guided to the optical pupil via the eyepiece optical system 4. Thereby, at the position of the optical pupil, the observer can observe the image of the image display device 1 as a virtual image. At the same time, the observer can observe the external image through the eyepiece optical system 4 in a see-through manner. In addition, you may enable it to observe an image | video with both eyes using two image display apparatuses 1. FIG.

  Further, since the video display device 1 is supported in front of the observer's eyes by the support means 2, the observer becomes hands-free and can perform a desired operation with his free hand while observing the video and the external image. Details of the video display device 1 will be described below.

(2. Configuration of video display device)
FIG. 3 is a cross-sectional view illustrating a schematic configuration of the video display device 1. The video display device 1 includes a light source 11, a unidirectional diffuser plate 12, a condenser lens 13, a display element 14, and the eyepiece optical system 4 described above. Also in FIG. 3, illustration of the protection means described later is omitted for convenience.

  The light source 11, the one-way diffuser plate 12, the condenser lens 13, and the display element 14 are accommodated in the housing 3 shown in FIG. 2, and a part of an eyepiece prism 21 described later is also located in the housing 3. ing. Moreover, although the illumination optical system is comprised by the light source 11, the one way diffuser plate 12, and the condensing lens 13, you may arrange | position DOE (diffractive optical element) in this illumination optical system as needed.

  For convenience of explanation below, directions are defined as follows. First, an axis that optically connects the center of the display area of the display element 14 and the center of the optical pupil E formed by the eyepiece optical system 4 is defined as an optical axis. The optical axis direction when the optical path from the light source 11 to the optical pupil E is developed is taken as the Z direction. In addition, a direction perpendicular to an optical axis incident surface of a hologram optical element 23 (to be described later) of the eyepiece optical system 4 is defined as an X direction, and a direction perpendicular to the ZX plane is defined as a Y direction. The optical axis incident surface of the hologram optical element 23 refers to a plane including the optical axis of incident light and the optical axis of reflected light in the hologram optical element 23, that is, the YZ plane. In each of the XYZ directions, positive or negative is not questioned.

  The light source 11 illuminates the display element 14. For example, the light source 11 is 462 ± 12 nm (B light), 525 ± 17 nm (G light), 635 ± 11 nm (R It is composed of RGB-integrated LEDs that emit light in three wavelength bands. As described above, the light source 11 emits light having a predetermined wavelength width, so that the image light obtained by illuminating the display element 14 can have a predetermined wavelength width. When the image light is diffracted, the image can be observed by the observer over the entire observation angle of view at the position of the optical pupil E. In addition, the peak wavelength for each color of the light source 11 is set in the vicinity of the peak wavelength of diffraction efficiency, which will be described later, of the hologram optical element 23, thereby improving the light utilization efficiency.

  In addition, since the light source 11 is composed of LEDs that emit RGB light, the light source 11 can be realized at low cost and a color image is displayed on the display element 14 when the display element 14 is illuminated. It becomes possible to provide the observer with the color image. Further, since each LED has a narrow emission wavelength width, the use of a plurality of such LEDs enables high color reproducibility and bright image display.

  The unidirectional diffuser plate 12 diffuses the light emitted from the light source 11, but the degree of diffusion differs depending on the direction. More specifically, the unidirectional diffuser 12 diffuses incident light in the X direction by about 40 ° and diffuses incident light in the Y direction by about 0.5 °.

  The condensing lens 13 is composed of a cylinder lens that condenses the light diffused by the unidirectional diffusing plate 12 in the Y direction, and is arranged so that the diffused light efficiently forms the optical pupil E. .

  The display element 14 displays an image by modulating the light emitted from the light source 11 in accordance with image data, and is configured by a transmissive liquid crystal display element having pixels in a matrix in which light is transmitted. Has been. The display element 14 is arranged such that the long side direction of the rectangular display region is the X direction and the short side direction is the Y direction. The display element 14 may be a reflective type. As the reflective display element 14, for example, a reflective liquid crystal display element or DMD (Digital Micromirror Device; manufactured by Texas Instruments Inc., USA) can be used.

  The eyepiece optical system 4 is an enlargement optical system that provides an observer with an enlarged virtual image of a display image of the display element 14, and includes an eyepiece prism 21, a deflection prism 22, and a hologram optical element 23. .

  The eyepiece prism 21 is a light guide member that guides the image light from the display element 14 inside and guides it to the optical pupil E, and transmits external light. The eyepiece prism 21 is made of, for example, an acrylic resin together with the deflection prism 22. Yes. The eyepiece prism 21 is formed in a shape in which the lower end portion of the parallel plate is wedge-shaped and the upper end portion is thickened. That is, the eyepiece prism 21 includes a parallel plate. Further, the eyepiece prism 21 is joined to the deflection prism 22 with an adhesive so as to sandwich the hologram optical element 23 disposed at the lower end thereof.

  The eyepiece prism 21 has surfaces 21a to 21d as optical surfaces. The surface 21a is an incident surface on which the image light from the display element 14 is incident. The surfaces 21b and 21c are arranged in parallel to each other, and are total reflection surfaces that totally reflect the image light incident on the prism via the surface 21a. The surface 21d is a surface on which the hologram optical element 23 is formed, and is a reflection surface that reflects the image light totally reflected by the surfaces 21b and 21c and guides it to the optical pupil E.

  The deflecting prism 22 is configured by a substantially U-shaped parallel plate in plan view (see FIG. 2), and when the deflecting prism 22 is bonded to the lower end portion and both side surface portions (left and right end surfaces) of the eyepiece prism 21, the eyepiece prism. 21 is a substantially parallel flat plate. The deflection prism 22 is a correction member that is joined via the surface 21 d of the eyepiece prism 21 to cancel out refraction of external light at the eyepiece prism 21. By using such a deflecting prism 22, it is possible to prevent distortion in the external image observed by the observer via the eyepiece optical system 4.

  That is, for example, when the deflecting prism 22 is not joined to the eyepiece prism 21, the external light is refracted when passing through the wedge-shaped lower end of the eyepiece prism 21, so that the external field image observed through the eyepiece prism 21 is distorted. Arise. However, the deflection prism 22 is joined to the eyepiece prism 21 to form an integral substantially parallel plate, so that the deflection when the external light passes through the wedge-shaped lower end of the eyepiece prism 21 is canceled by the deflection prism 22. Can do. As a result, it is possible to prevent distortion in the external image observed through the see-through.

  Note that the two surfaces of the eyepiece prism 21 and the deflection prism 22 facing each other may be flat surfaces or curved surfaces. If the two surfaces are curved surfaces, the eyepiece optical system 4 can have a function as a correcting spectacle lens.

  The hologram optical element 23 diffracts and reflects the image light (wavelength corresponding to the three primary colors) from the display element 14 and guides it to the optical pupil E. At the same time, the hologram optical element 23 transmits external light and guides it to the optical pupil E. Type reflection hologram. The hologram optical element 23 has, for example, three wavelength ranges of 465 ± 5 nm (B light), 521 ± 5 nm (G light), and 634 ± 5 nm (R light) with a peak wavelength of diffraction efficiency and a wavelength width of half value of diffraction efficiency. The light is diffracted (reflected). Here, the peak wavelength of diffraction efficiency is the wavelength at which the diffraction efficiency reaches a peak, and the wavelength width at half maximum of the diffraction efficiency is the wavelength width at which the diffraction efficiency is at half the peak of the diffraction efficiency. It is.

  The reflection-type hologram optical element 23 has high wavelength selectivity, and only diffracts and reflects light having a wavelength in the wavelength range (near the exposure wavelength). Through the hologram optical element 23, a high external light transmittance can be realized.

  Further, the hologram optical element 23 has an axially asymmetric positive optical power. That is, the hologram optical element 23 has the same function as an aspherical concave mirror having positive power. Thereby, the degree of freedom of arrangement of each optical member constituting the apparatus can be increased, and the apparatus can be easily reduced in size, and a well-corrected aberration corrected image can be provided to the observer as an enlarged virtual image.

(3. Operation of video display device)
Next, the operation of the video display device 1 having the above configuration will be described. The light emitted from the light source 11 is diffused by the unidirectional diffusion plate 12, condensed by the condenser lens 13, and enters the display element 14. The light incident on the display element 14 is modulated for each pixel based on the image data and is emitted as video light. That is, a color image is displayed on the display element 14.

  The image light from the display element 14 enters the eyepiece prism 21 of the eyepiece optical system 4 from its upper end surface (surface 21a), and is totally reflected a plurality of times by the two opposing surfaces 21b and 21c. 23 is incident. The light incident on the hologram optical element 23 is reflected there, passes through the surface 21c, and reaches the optical pupil E. Therefore, at the position of the optical pupil E, the observer can observe an enlarged virtual image of the video displayed on the display element 14.

  On the other hand, the eyepiece prism 21, the deflecting prism 22, and the hologram optical element 23 transmit almost all of the outside light, so that the observer can observe the outside world image through them. Therefore, the virtual image of the image displayed on the display element 14 is observed while being overlapped with a part of the external image.

  As described above, in the video display device 1, the video light emitted from the display element 14 is guided by total reflection in the eyepiece prism 21 and guided to the observer's pupil via the hologram optical element 23. Similar to the spectacle lens, the thickness of the eyepiece prism 21 and the deflecting prism 22 can be about 3 mm, and the video display device 1 can be reduced in size and weight. Further, by using the eyepiece prism 21 that totally reflects the image light from the display element 14, a high external light transmittance can be secured and a bright external image can be provided to the observer. Furthermore, since the eyepiece prism 21 is configured to include a parallel plate, the eyepiece prism 21 itself can be made thin, and the video display device 1 and thus the HMD can be downsized.

  Further, the volume phase type reflection type hologram optical element 23 has a narrow diffraction efficiency half-value wavelength width and a high diffraction efficiency. By using such a hologram optical element 23, a color image with high color purity and high brightness can be obtained. In addition to providing high external light transmittance, the observer can observe a bright external image. Moreover, since the conjugate relationship between the light source 11 and the optical pupil E is not changed, the wavelength of the image light does not change, and an image with high color reproducibility can be provided.

  Further, as can be seen from the above description, the hologram optical element 23 functions as a combiner that guides the image light and the external light from the display element 14 to the observer's pupil at the same time. As a result, the observer can simultaneously observe the image provided from the display element 14 and the external image via the hologram optical element 23.

(4. Protection measures)
Next, protection means will be described. FIG. 1 is a cross-sectional view schematically showing the main part of the video display device 1 of the present embodiment including the protection means 31. As shown in the figure, the video display device 1 has a protection means 31. The protection means 31 protects the total reflection surface (at least one of the surfaces 21b and 21c) of the eyepiece prism 21 of the eyepiece optical system 4. In the present embodiment, the protection means 31 includes a protection substrate 32 and a support member 33. Configured. The protective substrate 32 and the support member 33 may be configured separately and detachable (detachable) from each other, or may be configured integrally.

  The protective substrate 32 is configured by a transparent thin thin flat plate, and is disposed, for example, via the surfaces 21b and 22b of the eyepiece prism 21 and the deflection prism 22 facing the protective substrate 32 and an air layer. The surface 22b is located on the same surface as the surface 21b.

The support member 33 supports the protective substrate 32 in contact with a region where the image light is not totally reflected on the total reflection surface of the eyepiece prism 21. That is, the surface 21b which is the total reflection surface of the eyepiece prism 21 is not totally reflected (no image light is incident) and is not totally reflected (total image area is not incident), and the total reflection region 21b ₁ where the image light from the display element 14 is incident and totally reflected. When and a region 21b _2, the support member 33 supports the protective substrate 32 in contact with non-total reflection area 21b ₂ of the surface 21b. The support member 33 only needs to be in contact with at least the non-total reflection region 21b _2, and may further be in contact with the surface 22b of the deflection prism 22 as shown in FIG.

  Thus, since the protective substrate 32 is disposed via the surface 21b of the eyepiece prism 21 and the air layer, the refractive index difference between the eyepiece prism 21 and the air layer, which are the two media sandwiching the surface 21b. Surely occurs. In addition, the protective substrate 32 prevents direct adhesion of external foreign matter P such as raindrops and hand oil to the surface 21b. Therefore, for these two reasons, the image light from the display element 14 is reliably totally reflected by the surface 21b in the eyepiece prism 21 and guided inside. Therefore, the wave front of the image light is not disturbed due to the foreign matter P, and the image light is guided to the optical pupil E through a normal optical path. Therefore, it is possible to avoid the deterioration of the quality of the image observed at the position of the optical pupil E due to the foreign matter P with a simple configuration in which the protective substrate 32 is provided via the surface 21b and the air layer. .

Further, since the protective substrate 32 is supported by the support member 33 that comes into contact with the surface 21b, the thickness of the air layer, that is, the surface, while the air layer is reliably interposed between the surface 21b and the protective substrate 32, is the surface. It becomes easy to minimize the distance between 21b and the protective substrate 32. As a result, the above-described effects can be obtained while easily downsizing the apparatus. Moreover, since the support member 33 is in contact with the non-total reflection region 21b ₂ of the surface 21b, the support member 33 does not prevent total reflection of the image light on the surface 21b (particularly, the total reflection region 21b ₁ ). The image light can be reliably totally reflected and guided through the eyepiece prism 21.

  The space surrounded by the surface 21b, the protective substrate 32, and the support member 33 (the above air layer) is preferably sealed in terms of preventing the entry of water droplets as the foreign matter P, but the sealing is always necessary. It is not done. Since water droplets are unlikely to enter from below to above, for example, an opening may be formed in the lower portion of the support member 33 (the contact portion with the lower end portion of the surface 22b of the deflection prism 22).

  4A is a horizontal sectional view of the eyepiece optical system 4 of the video display device 1 of FIG. 1, and FIG. 4B is a view from the opposite side of the optical pupil E of the eyepiece optical system 4. A plan view is shown. 5A shows a horizontal sectional view of the eyepiece optical system 4 of another image display device 1, and FIG. 5B shows a plane from the opposite side of the eyepiece optical system 4 to the optical pupil E. The figure is shown. Here, it is assumed that the protective substrate 32 covers the entire surfaces 21b and 22b. 4B and 5B, for the sake of convenience, illustration of the protective substrate 32 is omitted and the support member 33 is indicated by hatching.

4 (a) and 4 (b), the support member 33 has a non-total reflection region 21b ₂ (see FIG. 4) on the surface 21b so that the protective substrate 32 faces both the eyepiece prism 21 and the deflection prism 22 through an air layer. 1) and further contacts the peripheral edge of the surface 22b to support the protective substrate 32. On the other hand, in FIGS. 5A and 5B, the support member 33 protects at least the entire surface 22b of the deflecting prism 22 so that an air layer is interposed only between the protective substrate 32 and the surface 21b. The substrate 32 is supported.

  5A and 5B, the ridge line L of the support member 33 appears corresponding to the joint line portion between the eyepiece prism 21 and the deflecting prism 22. Since the position where the ridge line L appears is close to the axis passing through the center of the optical pupil E and close to the center of the visual field, the observer can easily view the ridge line L. On the other hand, in the configuration of FIGS. 4A and 4B, the position of the ridge line L of the support member 33 is away from the axis passing through the center of the optical pupil E and away from the center of the field of view. Even when the image is observed, it is difficult to visually recognize the ridge line L, and it is possible to observe the external image satisfactorily.

  That is, in terms of protecting the surface 21b of the eyepiece prism 21, either of the configurations shown in FIGS. 4A and 4B and FIGS. 5A and 5B may be used, but in terms of making it easier to observe an external image, The configuration shown in FIGS. 4A and 4B is more desirable.

  FIG. 6 is a cross-sectional view schematically showing still another configuration of the video display device 1. As shown in the figure, the two protective means 31 may be provided on the optical pupil E side and the opposite side of the optical pupil E in the eyepiece optical system 4. That is, the two protection means 31 and 31 may be provided corresponding to the surface 21b (first surface) and the surface 21c (second surface) of the eyepiece prism 21.

  With this configuration, it is possible to prevent the foreign matter P from directly adhering to the surfaces 21 b and 21 c of the eyepiece prism 21. That is, for example, when the video display device 1 is carried or attached to an observer of the HMD, the observer may touch the eyepiece optical system 4 with fingers from both sides. However, even in that case, in the configuration of FIG. 6, the observer's finger comes into contact with each of the protective substrates 32 and 32 and does not come into direct contact with the surfaces 21b and 21c. Does not adhere directly. Therefore, it can be avoided that the wavefront of the image light totally reflected on both surfaces 21b and 21c due to the external foreign matter P is disturbed and the quality of the observed image is deteriorated.

  FIGS. 7A and 7B are cross-sectional views schematically showing still another configuration of the video display device 1. As shown in these drawings, the protection substrate 32 of the protection means 31 is composed of a member (for example, a lens) having optical power for diopter correction of the observer. In FIG. 7A, the protection substrate 32 of the protection means 31 on the side opposite to the optical pupil E (surface 21b side) with respect to the eyepiece prism 21 has optical power. On the other hand, in FIG. 7B, the protective substrate 32 of the protection means 31 on the optical pupil E side (surface 21c side) with respect to the eyepiece prism 21 has optical power.

  In this way, by providing the protective substrate 32 with optical power, the protection means 31 has both functions of preventing the deterioration of the image quality caused by the external foreign matter P and the function of correcting the diopter of the observer. You can have it. At this time, the protective substrate 32 and the support member 33 may be detachable or may be configured integrally. If the protective substrate 32 is detachably supported by the support member 33, the protective substrate 32 having optical power corresponding to the observer to be used can be used, and diopter correction corresponding to the observer to be used is possible. Become.

  Moreover, the protective substrate 32 can further have a function of adjusting the transmittance of external light. Adjustment of the transmittance at this time may be performed by a light-reducing coating such as general sunglasses, or may be performed by a liquid crystal shutter that can be electrically controlled.

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

  FIG. 8A is a cross-sectional view schematically showing a schematic configuration of the video display device 1 of the present embodiment. FIG. 8B is a horizontal sectional view of the eyepiece optical system 4 of the video display device 1, and FIG. 8C is a plan view from the side opposite to the optical pupil E of the eyepiece optical system 4. is there. In the present embodiment, the protection means 31 of the video display device 1 is configured to include a water repellent film 34 and a hydrophilic film 35. In FIG. 8B, the protection means 31 on the optical pupil E side with respect to the eyepiece optical system 4 is not shown.

  The water repellent film 34 is a film having water repellency, and is covered on the surfaces 21 b and 21 c of the eyepiece prism 21. The hydrophilic film 35 is a hydrophilic film and is covered on the surfaces 22 b and 22 c of the deflecting prism 22. The surfaces 22b and 22c are surfaces located on the same surface as the surfaces 21b and 21c, respectively.

  In this way, by covering the surfaces 21b and 21c of the eyepiece prism 21 with the water repellent film 34, if the external foreign matter P is a water droplet, the water droplets are prevented from directly adhering to the surfaces 21b and 21c. The water droplets can be reduced by the water repellent film 34 and scattered. Therefore, the image light guided through the eyepiece prism 21 is reliably totally reflected by the surfaces 21b and 21c, and the wavefront of the image light is not disturbed due to the water droplets. As a result, it is possible to prevent the quality of the observed display image from being deteriorated due to water droplets with a simple configuration in which the surfaces 21b and 21c are covered with the water repellent film 34.

  Further, since the water droplets repelled by the water repellent film 34 are caught by the hydrophilic film 35 coated on the surfaces 22b and 22c of the deflecting prism 22, the water droplets do not move with each other on the surfaces 22b and 22c. The water drops do not get in the way. When the hydrophilic film 35 is provided, it becomes difficult for the observer to observe the external image somewhat, but the degradation of the observed video quality can be avoided. Therefore, for example, when it is desired to use the video display device 1 as visual assistance (when it is necessary to observe the video more firmly than the outside), the video display device 1 of the present embodiment is very effective.

  In the present embodiment, the case where the protection means 31 has both the water repellent film 34 and the hydrophilic film 35 has been described. However, at least if the protective means 31 has the water repellent film 34, that is, the surface 21b. -If the water-repellent film 34 is covered on 21c, the deterioration of the quality of the observation image can be avoided. Of course, the water repellent film may be covered on the surfaces 21b and 21c and the surfaces 22b and 22c.

  In the present embodiment, the protection means 31 is provided on both surfaces of the eyepiece optical system 4. However, for example, the protection means 31 may be provided only on the side opposite to the optical pupil E with respect to the eyepiece optical system 4. I do not care. However, from the viewpoint of reliably preventing disturbance of the wavefront of the image light guided by total reflection on both surfaces 21b and 21c, it is desirable to provide the protection means 31 on both surfaces of the eyepiece optical system 4.

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

  FIG. 9A is a cross-sectional view schematically showing a schematic configuration of the video display device 1 of the present embodiment, and FIG. 9B is an enlarged cross-sectional view showing the main part of the video display device 1. FIG. In the video display device 1 of the present embodiment, the protection means 31 further includes an attachment member 36 in the configuration of the second embodiment.

  The attachment member 36 is an accessory that is detachably attached to the video display device 1, and here, is constituted by an attachment lens having optical power. The attachment member 36 may be external light transmittance control means such as a semi-transmissive plate for adjusting the transmittance of external light. The attachment member 36 is disposed, for example, via the eyepiece prism 21 and the air layer by being supported by the support means 2 (see FIG. 2). A surface of the attachment member 36 facing the eyepiece prism 21 (surface 36a) is covered with a hydrophilic film 37 having hydrophilicity.

  By disposing the attachment member 36 thus coated with the hydrophilic film 37 via the eyepiece prism 21 and the air layer, even if a foreign matter P such as a water droplet enters the air layer, the surface of the eyepiece prism 21 is provided. Since the water repellent film 34 is coated on 21b, the water droplet does not adhere to the eyepiece prism 21 side but adheres to the attachment member 36 side coated with the hydrophilic film 37. Therefore, the wavefront of the image light guided through the eyepiece prism 21 is not disturbed due to the water droplets, and the deterioration of the quality of the observation image can be avoided.

  FIG. 10A is a cross-sectional view schematically showing another configuration of the video display device 1, and FIG. 10B is a cross-sectional view showing an enlarged main part of the video display device 1. is there. This video display device 1 is the same as the video display device 1 shown in FIGS. 9A and 9B except that the surface 36a of the attachment member 36 is covered with a water-repellent water-repellent film 38 instead of the hydrophilic film 37. It is the composition.

  In this configuration, even if water droplets as foreign matter P enter the air layer between the eyepiece prism 21 and the attachment member 36, the surface 21b and the surface 36a are covered with the water-repellent films 34 and 38, respectively. The water droplet falls without adhering to both the eyepiece prism 21 and the attachment member 36. Therefore, even with this configuration, the wavefront of the image light guided through the eyepiece prism 21 is not disturbed due to the water droplets, and deterioration of the quality of the observed image can be avoided.

  Of course, the video display device 1 and the HMD can be configured by appropriately combining the configurations of the above-described embodiments.

  The present invention is applicable to HMD.

It is sectional drawing which shows typically the principal part of the video display apparatus concerning one Embodiment of this invention. It is a perspective view which shows the structure of the outline of HMD which has the said video display apparatus. It is sectional drawing which shows the schematic structure of the said video display apparatus. (A) is a horizontal sectional view of the eyepiece optical system of the video display device, and (b) is a plan view from the side opposite to the optical pupil of the eyepiece optical system. (A) is a horizontal sectional view of an eyepiece optical system of another video display device, and (b) is a plan view from the side opposite to the optical pupil of the eyepiece optical system. It is sectional drawing which shows typically another structure of a video display apparatus. (A) is sectional drawing which shows typically the structure of the video display apparatus which gave the optical power to the protective substrate of the protection means on the opposite side to an optical pupil with respect to an eyepiece prism, (b), It is sectional drawing which shows typically the structure of the video display apparatus which gave the optical power to the protective substrate of the protection means of the optical pupil side with respect to the eyepiece prism. (A) is sectional drawing which shows typically the outline structure of the video display apparatus which concerns on other embodiment of this invention, (b) is a horizontal sectional view of the eyepiece optical system of the said video display apparatus. (C) is a plan view from the opposite side of the optical pupil of the eyepiece optical system. (A) is sectional drawing which shows typically the structure of the outline of the video display apparatus concerning further another embodiment of this invention, (b) expands and shows the principal part of the said video display apparatus. It is sectional drawing. (A) is sectional drawing which shows typically the other structure of a video display apparatus, (b) is sectional drawing which expands and shows the principal part of the said video display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image display apparatus 2 Support means 4 Eyepiece optical system 14 Display element 21 Eyepiece prism (light guide member)
21b surface (total reflection surface, first surface)
21b ₁ total reflection area 21b ₂ non-total reflection area 21c surface (total reflection surface, second surface)
21d surface (reflection surface)
22 Deflection prism (correction member)
22b surface 22c surface 31 Protective means 32 Protective substrate 33 Support member 34 Water repellent film 35 Hydrophilic film 36 Attachment member 37 Hydrophilic film 38 Water repellent film E Optical pupil

Claims (18)

A display element for displaying an image;
An image display device comprising an eyepiece optical system having a light guide member that guides image light from a display element inside and guides it to an optical pupil,
The light guide member has a total reflection surface including a region that totally reflects the image light from the display element, and a reflection surface that reflects the image light totally reflected by the total reflection surface and guides it to the optical pupil. ,
The video display device further includes a protection means for protecting the total reflection surface,
Protective measures are
A protective substrate disposed through the total reflection surface and the air layer;
An image display device comprising: a support member that supports a protective substrate in contact with a region where image light is not totally reflected on the total reflection surface.   The video display device according to claim 1, wherein the light guide member transmits external light.   The video display device according to claim 2, wherein the protective substrate is transparent.   The eyepiece optical system further includes a correction member that is joined via a reflection surface of the light guide member and that cancels refraction of external light at the light guide member. The video display device described.   The support member supports the protective substrate in further contact with the peripheral portion of the surface of the correction member on the protective substrate side so that the protective substrate faces both the light guide member and the correction member via the air layer. The video display device according to claim 4. The total reflection surface is composed of a first surface opposite to the optical pupil in the light guide member, and a second surface on the optical pupil side,
6. The video display device according to claim 1, wherein the protection means is provided corresponding to the first surface and the second surface.   The video display device according to claim 1, wherein the protective substrate has optical power.   The video display device according to claim 7, wherein the protective substrate is detachably supported by the support member. A display element for displaying an image;
An image display device comprising an eyepiece optical system having a light guide member that guides image light from a display element inside and guides it to an optical pupil,
The light guide member has a total reflection surface that totally reflects image light from the display element, and a reflection surface that reflects the image light totally reflected by the total reflection surface and guides it to the optical pupil,
The video display device further includes a protection means for protecting the total reflection surface,
An image display device characterized in that the protection means has a transparent water-repellent film having water repellency, which is coated on the total reflection surface.   The video display device according to claim 9, wherein the light guide member transmits external light. The protection means further includes a removable attachment member disposed via the light guide member and the air layer,
The image display device according to claim 10, wherein a surface of the attachment member on the light guide member side is covered with a hydrophilic film having hydrophilicity. The protection means further includes a removable attachment member disposed via the light guide member and the air layer,
The video display device according to claim 10, wherein a surface of the attachment member on the light guide member side is coated with a water-repellent water-repellent film.   The eyepiece optical system further includes a correction member that is joined through a reflection surface of the light guide member and cancels refraction of external light at the light guide member. The video display apparatus in any one. The correction member has a surface located on the same surface as the total reflection surface of the light guide member,
14. The image display device according to claim 13, wherein the surface of the correction member is coated with a hydrophilic film.   The video display device according to claim 1, wherein the light guide member includes a parallel plate. The reflection surface of the light guide member is a surface on which a volume phase reflection hologram optical element is formed,
16. The hologram optical element according to claim 1, wherein image light from the display element is diffracted and reflected and guided to the optical pupil, and at the same time, external light is transmitted and guided to the optical pupil. Video display device.   The video display device according to claim 16, wherein the hologram optical element has an axially asymmetric positive optical power. A video display device according to any one of claims 1 to 17,
A head-mounted display comprising support means for supporting the video display device in front of an observer's eyes.

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