JP2010139589A - Video image display apparatus and head mounted display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate uncomfortable feeling by eliminating a problem that a gazing virtual image V is buried in a back ground B and observed when the position of the back ground B comes closer to an optical pupil E side than the position of the gazing virtual image. <P>SOLUTION: An video image display apparatus has a virtual image position changing part. The virtual image position changing part is constituted, for example, of a virtual image distance changing part. The virtual image distance changing part changes a distance from an optical pupil E to the virtual image V, for example, by changing the relative distance of an LCD and an eyepiece optical system. By such a virtual image position changing part, when the position of the back ground B comes closer to the optical pupil E side than the position of the virtual image V before changing position, the gazing virtual image position is forcibly changed so that the position of the virtual image V comes closer to the optical pupil E side than the back ground B. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a video display device and a head mounted display (hereinafter also referred to as HMD) including the video display device.

  2. Description of the Related Art Conventionally, various video display apparatuses that can observe a virtual image of a display video and a background superimposed on each other in a see-through manner have been proposed. Among them, the devices disclosed in Patent Documents 1 and 2 both detect the observer's line of sight to obtain the gazing point, and change the display position (virtual image distance) of the virtual image to the position of the gazing point. Yes. Thereby, it is possible to reduce fatigue of the eyes of the observer.

Japanese Patent Publication No. 6-85590 Japanese Patent No. 2994960

  By the way, depending on the usage environment and usage state of the video display device, the position of the background observed through see-through may be closer to the viewer side than the position of the virtual image to be watched. For example, when the wall of the room is originally located in front of the video display device or when the observer moves (rotates) in the left-right direction, the wall is located in front of the device. Happens. Observing a virtual image in such a state would result in a situation that cannot exist in reality because an image exists beyond the background, and as a result, the virtual image is embedded in the background and the observer feels uncomfortable. feel.

  The present invention has been made to solve the above-described problems, and its purpose is to embed a virtual image in the background when the position of the background is closer to the observer side than the position of the gaze virtual image. An object of the present invention is to provide a video display device capable of eliminating the feeling of discomfort by avoiding being observed, and an HMD including the video display device.

  An image display apparatus according to the present invention includes a display element for displaying an image and an eyepiece optical system that guides image light from the display element to an optical pupil, and at the position of the optical pupil, a background is displayed with a virtual image of the display image. A gaze virtual image position changing unit that changes the position of the gaze virtual image, and a background distance measurement unit that measures the distance from the background video display device that is observed to overlap the gaze virtual image. The gaze virtual image position changing means includes at least a part of the background more than the gaze virtual image position based on the distance of the gaze virtual image position from the optical pupil and the measurement result of the background distance measurement means. When it is determined that the position is close to the side, the gaze virtual image position is changed so as to be closer to the optical pupil side than at least a part of the background.

  In the video display device of the present invention, the gaze virtual image position changing unit may include a gaze virtual image distance changing unit that changes the gaze virtual image position by changing a distance of the gaze virtual image from the optical pupil. Good.

  The video display device of the present invention includes a left-eye display unit and a right-eye display unit corresponding to the left and right eyes of the observer, and both the display units include the display element and the eyepiece optical system. The gaze virtual image position changing unit may include a convergence angle changing unit that changes the gaze virtual image position by changing the convergence angle.

  In the video display device of the present invention, the gaze virtual image position changing unit further includes a gaze virtual image distance changing unit that changes the gaze virtual image position by changing a distance of the gaze virtual image from the optical pupil. Also good.

  In the video display device of the present invention, the gaze virtual image distance changing unit may change the distance of the gaze virtual image from the optical pupil by changing a relative distance between the display element and the eyepiece optical system. .

  In the video display device of the present invention, the convergence angle changing means may change the convergence angle by relatively rotating the display unit for the left eye and the display unit for the right eye.

  In the video display device of the present invention, the convergence angle changing means shifts at least one of the videos displayed on the display elements of the left-eye display unit and the right-eye display unit in a direction corresponding to the eye width of the observer. The convergence angle may be changed by displaying.

  In the video display device of the present invention, when the gaze virtual image position changing unit determines that a part of the background observed to overlap the gaze virtual image is closer to the optical pupil side than the gaze virtual image position, It is desirable to change the virtual image position so that it is closer to the optical pupil side than a part of the background.

  In the video display device of the present invention, it is preferable that the gaze virtual image position changing unit changes the gaze virtual image position stepwise.

  In the video display device of the present invention, the gaze virtual image position changing means has at least a part of a background overlapping the gaze virtual image closer to the optical pupil side than a reference virtual image position preset as a reference of the gaze virtual image position. The reference virtual image is within a range closer to the optical pupil side than at least a part of the background, when the gaze virtual image position is changed so as to approach the optical pupil side when the optical pupil moves away from the optical pupil. It is desirable to change so that it may approach a position.

  In the image display device according to the aspect of the invention, the eyepiece optical system includes an optical member that guides the image light from the display element by total reflection inside, and diffracted and reflects the image light guided in the optical member. It may be configured to include a volume phase type reflection type hologram optical element that is guided to the optical pupil.

  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.

  A head-mounted display according to the present invention includes the above-described video display device according to the present invention and support means for supporting the video display device in front of an observer's eyes.

  According to the present invention, at least a part of the background (which may be the whole background overlapping the display virtual image or a part of the background overlapping the display virtual image) may be the gaze virtual image by the gaze virtual image position changing unit. When it is determined that the position is closer to the optical pupil side than the position, the gaze virtual image position is forcibly changed so as to be closer to the optical pupil side than at least a part of the background. Accordingly, it is possible to avoid the observation virtual image from being embedded in the background when at least a part of the background is close to the optical pupil side, and to eliminate the uncomfortable feeling caused by the observation.

  An embodiment of the present invention will be described below with reference to the drawings.

(About HMD)
2A is a plan view showing a schematic configuration of the HMD according to the present embodiment, FIG. 2B is a front view of the HMD, and FIG. 2C is a side view of the HMD. is there. The HMD has a video display device 1 and support means 2 for supporting it, and as a whole has an appearance like general glasses. The HMD has a symmetrical shape in the left and right eye width directions.

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

  The support means 2 supports the video display units 1R and 1L in front of the right and left eyes of the observer, and includes a bridge 3, a frame 4, a temple 5, a nose pad 6, a cable 7, And a background distance measuring unit 8 and a convergence angle changing unit 9. The frame 4, the temple 5, the nose pad 6, and the cable 7 are provided as a pair on the left and right sides. However, in order to distinguish between the left and right, the right frame 4R, the left frame 4L, the right temple 5R, the left temple 5L, the right It is expressed as a nose pad 6R, a left nose pad 6L, a right cable 7R, and a left cable 7L.

  The bridge 3 connects the video display units 1R and 1L. The right temple 5R is rotatably supported by the right frame 4R, and is connected to the video display unit 1R (on the side opposite to the connection side to the bridge 3) via the right frame 4R. Similarly, the left temple 5L is rotatably supported by the left frame 4L, and is connected to the video display unit 1L (on the side opposite to the connection side to the bridge 3) via the left frame 4L. . The nose pad 6 is supported by the bridge 3.

  The cable 7 is a wiring for supplying an external signal (for example, a video signal, a control signal) and power to the video display units 1R and 1L. The right cable 7R is provided along the right temple 5R and the right frame 4R and connected to the video display unit 1R, and the left cable 7L is provided along the left temple 5L and the left frame 4L, and the video display unit. 1L is connected.

  The background distance measuring unit 8 is a background distance measuring unit that measures the distance from the optical pupil E of the background or the image display device 1 that is observed while overlapping the gaze virtual image, and is provided in the bridge 3. In the present embodiment, the gaze virtual image position is changed when at least part of the background is closer to the optical pupil E side than the gaze virtual image position based on the measurement result in the background distance measurement unit 8. The point will be described later. The optical pupil E is an exit pupil (observation pupil) formed by an eyepiece optical system 21 described later of the video display device 1.

  The background distance measurement unit 8 includes a measurement sensor and a calculation unit. Here, the distance from the optical pupil E in the background is represented by the sum of the distance from the optical pupil E to the bridge 3 (video display device 1) and the distance from the bridge 3 (video display device 1) to the background. However, the former distance is predetermined by the design of the apparatus. Therefore, the measurement sensor measures the distance from the bridge 3 to the background, and the calculation unit performs an operation of adding this distance and the distance from the optical pupil E to the bridge 3 to obtain the distance from the optical pupil E in the background. It can be measured (calculated).

  As the measurement sensor, a commonly used measurement means can be used. For example, an active autofocus (AF) that measures an object by irradiating an object with infrared rays or ultrasonic waves, and the reflected wave return time and angle, or a passive AF that measures a distance using an image captured by a lens Such means can be used.

  The convergence angle changing unit 9 changes the convergence angle by relatively rotating the video display units 1R and 1L with a vertical axis 9a provided in the bridge 3 as a rotation axis. It is comprised with the mechanical drive mechanism using. The convergence angle changing unit 9 is provided to change the gaze virtual image position, which will be described later. In the present embodiment, only one shaft 9a is provided at the center of the bridge 3, but two shafts 9a may be provided.

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

  Thus, since the video display apparatus 1 is supported in front of the observer's eyes by the support means 2, the observer can observe the video provided from the video display apparatus 1 in a hands-free manner. In addition, since the observation direction of the observer is determined in one direction, there is an advantage that the observer can easily search for a display image even in a dark environment.

(About the video display unit)
Next, details of the video display units 1R and 1L described above will be described. FIG. 3 is a cross-sectional view showing a schematic configuration of the video display units 1R and 1L. Each of the video display units 1R and 1L includes a video display unit 11 and an eyepiece optical system 21. The video display unit 11 includes a light source 12, a unidirectional diffuser plate 13, a condenser lens 14, and an LCD 15.

  The light source 12 is composed of an RGB-integrated LED that emits light in three wavelength bands whose central wavelengths are, for example, 465 nm, 520 nm, and 635 nm. For example, the RGB light emitting units of the light source 12 are arranged side by side in a horizontal direction (a direction perpendicular to the paper surface of FIG. 3) corresponding to the left and right direction when the observer wears the HMD.

  The unidirectional diffuser plate 13 diffuses illumination light from the light source 12, but the degree of diffusion differs depending on the direction. More specifically, the unidirectional diffuser plate 13 diffuses incident light by about 40 ° in the direction in which the RGB light emitting portions of the light source 12 are arranged (the horizontal direction), and a direction perpendicular to the diffused light (HMD by the observer). Incident light is diffused by about 0.2 ° in the up-and-down direction (direction parallel to the paper surface of FIG. 3) when it is mounted.

  The condenser lens 14 is an illumination optical system that condenses the light diffused by the unidirectional diffusion plate 13. The condenser lens 14 is disposed so that the diffused light efficiently forms the optical pupil E. The LCD 15 is a display element that displays an image by modulating light from the light source 12 for each pixel based on the image signal. In the present embodiment, the LCD 15 includes a transmissive liquid crystal display element.

  On the other hand, the eyepiece optical system 21 guides the image light from the LCD 15 to the optical pupil E, while transmitting the background light and guiding it to the optical pupil E, so that the background along with the virtual image of the display image is displayed at the position of the optical pupil. Let them see through. The eyepiece optical system 21 includes a cemented prism (a cemented optical member), and configures a telecentric optical system. Specifically, the eyepiece optical system 21 is formed by joining an eyepiece prism 22 and a deflection prism 23, which are optical members, with an optical element 24 interposed therebetween.

  The eyepiece prism 22 and the deflection prism 23 are joined with an adhesive. The eyepiece prism 22 is formed in a shape in which the lower end portion of the parallel plate is wedge-shaped and the upper end portion is thickened, and guides the image light from the LCD 15 by totally reflecting it internally. The eyepiece prism 22 has surfaces 22a, 22b, and 22c. The surface 22a is an incident surface on which image light from the image display unit 11 is incident, and the surfaces 22b and 22c are surfaces facing each other. Among these, the surface 22b is a total reflection surface and an emission surface.

  The deflection prism 23 is configured to be a substantially parallel flat plate integrally with the eyepiece prism 22 by forming the upper end portion of the parallel plate along the lower end portion of the eyepiece prism 22. When the deflecting prism 23 is not joined to the eyepiece prism 22, the background light is refracted when it passes through the wedge-shaped lower end of the eyepiece prism 22, so that the background observed through the eyepiece prism 22 is distorted. However, the deflection prism 23 is joined to the eyepiece prism 22 to form an integral substantially parallel plate, so that the deflection when the background light is transmitted through the wedge-shaped lower end of the eyepiece prism 22 is canceled by the deflection prism 23. be able to. As a result, it is possible to prevent the background observed with see-through from being distorted.

  The optical element 24 is a volume phase type reflection type hologram optical element (HOE) that diffracts and reflects the image light guided inside the eyepiece prism 22 and guides it to the optical pupil E, and is incident at a specific incident angle, for example. Diffract light in three wavelength bands of 465 ± 10 nm, 520 ± 10 nm, and 635 ± 10 nm. The optical element 24 is attached to the inclined surface at the lower end of the eyepiece prism 22, and as a result, is sandwiched between the eyepiece prism 22 and the deflection prism 23. By forming the HOE between the two transparent members (the eyepiece prism 22 and the deflection prism 23), the HOE does not come into contact with the outside air, so that the optical performance can be kept stable.

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

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

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

  As described above, the eyepiece optical system 21 includes the optical element 24 composed of a volume phase type and a reflection type HOE. Volume phase type reflection type HOE has high diffraction efficiency, and the half-value wavelength width of the diffraction efficiency peak is narrow. Therefore, a bright image can be observed by using such a HOE and adopting a configuration in which the image light from the LCD 15 is diffracted and reflected by the HOE and guided to the optical pupil E. Moreover, since the transmittance of external light is also increased, a bright external image (background) can be observed.

  In addition, since the video light is guided using total reflection in the eyepiece prism 22, the thickness can be reduced to the same level as that of a normal spectacle lens (for example, about 3 mm), and the eyepiece prism 22 can be made compact. In addition to being lightweight, the light transmittance of the background is increased, and the background can be observed well. Further, the LCD 15 can be arranged on one end side of the eyepiece optical system 21, that is, it can be arranged around the visual field, and a wide external field viewing angle can be secured.

  Further, since the HOE has positive optical power that is axially asymmetric to enlarge the image displayed on the LCD 15, the eyepiece optical system 21 can be made compact, and the arrangement of the optical members constituting the apparatus can be reduced. The degree of freedom can be increased, and the apparatus can be reduced in size and weight, and an image with good aberration correction can be observed.

  Further, as described above, since the optical element 24 is composed of a volume phase type reflection type HOE that diffracts only light having a specific wavelength at a specific incident angle, the image light from the LCD 15 is deflected by the eyepiece prism 22. The background light transmitted through the prism 23 and the optical element 24 is not affected. Therefore, the observer can observe the background clearly and normally through the eyepiece prism 22, the deflection prism 23 and the optical element 24 while observing the virtual image of the display image on the LCD 15 via the optical element 24. .

  The optical element 24 embedded in the reflection surface of the eyepiece optical system 21 may be a half mirror, a multilayer film, or the like, but it is more preferable to use the above-described volume phase type reflection type HOE. Since the volume phase type and reflection type HOE have both high wavelength selectivity and angle selectivity, they have a diffractive reflection effect only on light in a limited wavelength range. HOE can be effectively used as a combiner element that synthesizes transmitted light of other wavelengths.

  As a hologram photosensitive material for producing HOE, a photopolymer, a silver salt material, gelatin dichromate, or the like can be used. Among them, it is desirable to use a photopolymer that can be easily manufactured by a dry process.

(Change of gaze virtual image position (1))
Next, the change of the gaze virtual image position will be described. FIG. 4 is an explanatory diagram showing the configuration of the main part of the video display device 1 of the present embodiment. The video display device 1 includes a virtual image position changing unit 31, a virtual image distance storage unit 32, and the background distance measuring unit 8 (see FIGS. 2A and 2B). The virtual image position changing unit 31 is a gaze virtual image position changing unit that changes the position of the virtual image V that the observer gazes at. The virtual image distance storage unit 32 is a gazing virtual image distance storage unit that stores the distance from the optical pupil E of the virtual image V before and after the position change by the virtual image position change unit 31.

  Here, the virtual image position changing unit 31 is the distance from the optical pupil E of the gaze virtual image position, that is, the distance (diopter) of the virtual image V before the position change stored in the virtual image distance storage unit 32 and the background distance measuring unit. When it is determined that at least a part of the background observed by overlapping with the virtual image V is closer to the optical pupil E side than the position of the virtual image V before the position change based on the measurement result of FIG. It changes so that it may approach the optical pupil E side rather than at least one part of a background. In order to realize such a position change, the virtual image position changing unit 31 includes, for example, a virtual image distance changing unit 33.

  The virtual image distance changing unit 33 changes the position of the virtual image V by changing the distance of the virtual image V from the optical pupil E, and includes, for example, a drive unit 34 and a control unit 35. ing. The drive unit 34 is a mechanical drive mechanism that moves the LCD 15 in the optical axis direction, and includes a guide member (for example, a rail) and a motor. The control unit 35 controls driving of the driving unit 34. The optical axis mentioned above refers to an axis that optically connects the center of the display area of the LCD 15 and the center of the optical pupil E.

  Based on the control of the control unit 35, the drive unit 34 moves the LCD 15 in the optical axis direction, and changes the distance of the virtual image V from the optical pupil E by changing the relative distance between the LCD 15 and the eyepiece optical system 21. Is possible. For example, when the LCD 15 is brought closer to the eyepiece optical system 21, the virtual image V approaches the optical pupil E, and when the LCD 15 is moved away from the eyepiece optical system 21, the virtual image V is separated from the optical pupil E.

  FIG. 1 is a perspective view schematically showing a positional relationship among the optical pupil E, the virtual image V, and the background B. Here, a distance from the optical pupil E to the virtual image V before the position change is a gaze virtual image distance V1 (mm), and a distance from the optical pupil E to the background B is a background distance B1 (mm). The gaze virtual image distance V <b> 1 is determined according to the optical distance between the LCD 15 and the eyepiece optical system 21.

  Here, the gaze virtual image distance V1 is normally set in advance to a distance from the optical pupil E to the reference virtual image position D0 (see FIG. 6), and is stored in the virtual image distance storage unit 32 (see FIG. 4). Yes. The reference virtual image position D0 is a position that serves as a reference for the virtual image position, that is, the position of the virtual image V that allows the virtual image V to be observed well (with high resolution) without imposing a burden on the observer. Is set in advance at a position 1.5 m away from the virtual image distance and stored in the virtual image distance storage unit 32. That is, when the position of the background B is not taken into consideration, the virtual image V can be observed most satisfactorily by controlling the preset reference virtual image position D0 to be the gaze virtual image position. On the other hand, the background distance B1 is obtained by measurement in the background distance measurement unit 8 described above. The control unit 35 determines the magnitude relationship between the gaze virtual image distance V1 and the background distance B1.

  When it is determined from the relationship between the gaze virtual image distance V1 and the background distance B1 that the position of the background B is farther than the position of the virtual image V before the position change (V1 <B1), the observer views the virtual image V before the background B. Observation (gazing) does not cause a problem that the virtual image V is embedded in the background B and observed. On the other hand, if it is determined that the position of the background B is closer than the position of the virtual image V before the position change (V1> B1), there may exist an actual image that exists on the other side of the near background B. In this situation, since the virtual image V is embedded in the background B and observed, the observer feels uncomfortable. However, under the control of the control unit 35, the drive unit 34 changes the position of the virtual image V so that the LCD 15 approaches the eyepiece optical system 21 and approaches the optical pupil E side rather than the position of the background B. As a result, the gaze virtual image distance is changed from V1 to V2. However, V2 <B1 <V1. Note that the position of the virtual image V may be on the optical pupil E side with respect to the background B, but if it is too close to the optical pupil E, the burden on the observer is great and may give a feeling of fatigue. A position closer to the optical pupil E side and closer to the background B is desirable.

  In this way, when the background B is closer to the optical pupil E side than the gaze virtual image position (position of the gaze virtual image distance V1) by the virtual image position change unit 31 (virtual image distance change unit 33), it is more optical than the background B. Since the gaze virtual image position is forcibly changed so as to approach the pupil E side, the virtual image V is displayed in front of the background B, and the gaze virtual image V is embedded in the background B and observed. Can be avoided, and discomfort due to the observation can be eliminated. At this time, by changing the gaze virtual image distance from V1 to V2 by the virtual image distance changing unit 33, the gaze virtual image position can be easily changed.

  Further, since the virtual image distance changing unit 33 changes the distance of the virtual image V from the optical pupil E by changing the relative distance between the LCD 15 and the eyepiece optical system 21, the LCD 15 is changed to the eyepiece optical system 21 as described above. By approaching, the gaze virtual image distance can be easily shortened from V1 to V2. That is, it is possible to easily bring the gaze virtual image position closer to the optical pupil E side.

  Further, when the position of the virtual image V is changed so as to be closer to the optical pupil E side than the position of the background B, the changed position of the virtual image V (gaze virtual image distance V2) is stored in the virtual image distance storage unit 32. . Note that the position of the virtual image V at this time can be obtained based on the relative distance between the LCD 15 and the eyepiece optical system 21. In this way, by storing the position of the virtual image V after the position change, after that, even when the background B is closer to the optical pupil E side than the virtual image V, by repeating the same process as above, It can be avoided that the virtual image V is embedded in the background B and observed. That is, the gaze virtual image position can be changed based on the positional relationship between the position and the background B with the position of the virtual image V after the position change as a reference each time.

  In the above, when the entire background B overlapping the virtual image V is closer to the optical pupil E side than the position of the virtual image V, the position of the virtual image V is changed so as to be closer to the optical pupil E side than the background B. Although the example has been described, for example, the observer changes the observation direction of the background B to the left and right by moving (rotating) himself / herself while observing the virtual image V, so that a part of the background B overlapping the virtual image V is a virtual image. In some cases, it may be closer to the optical pupil E side than V. Even in such a case, it is desirable that the virtual image position changing unit 31 changes the position of the virtual image V so as to be closer to the optical pupil E side than a part of the background B, as shown in FIG. Since it is not realistic that even a part of the gazing virtual image V is embedded in the background B, the virtual image is changed by changing the gazing virtual image position when the background B is close to the optical pupil E side. Even if a part of V is embedded in the background B and observed, it is possible to eliminate the uncomfortable feeling caused by the observation.

  By the way, as shown in FIG. 4, when the virtual image position change part 31 (virtual image distance change part 33) changes a gaze virtual image position, it is desirable to change it in steps. That is, the virtual image distance changing unit 33 optically adjusts the position of the virtual image V like D0, D1, and D2 by moving the position of the LCD 15 relatively close to the eyepiece optical system 21 like L0, L1, and L2. It is desirable to bring it closer to the pupil E side. Note that “stepwise change” means that at least one gaze virtual image position (for example, D1) is provided between the initial gaze virtual image position (for example, D0) and the final gaze virtual image position (for example, D2) for a predetermined time. A change mode that only stops. The shift amount of the virtual image V can be adjusted by controlling the change amount of the relative distance between the LCD 15 and the eyepiece optical system 21.

  For example, when the distance difference between the background B and the virtual image V is originally large, when the background B approaches the optical pupil E side, the amount by which the virtual image V is shifted to the optical pupil E side increases. At this time, if the virtual image V is greatly shifted at a stretch, there is a possibility that the change in the actual gaze position of the observer cannot follow the shift of the virtual image V. For this reason, it is desirable to change the gaze virtual image position in a stepwise manner over time to induce the change of the gaze position of the observer. Specifically, it is desirable to change the position of the virtual image V stepwise over a period of 1 second or longer so that the observer can follow.

  In this way, the virtual image position changing unit 31 changes the gaze virtual image position in stages, so that the gaze virtual image position is gradually changed, so that the observer gazes (observes) the virtual image V at the position of the virtual image V. It is possible to cause the observer to observe the virtual image V after the position change by following the change well.

  FIG. 6 is an explanatory diagram schematically showing a state in which the background B once approaches the optical pupil E side and then leaves the optical pupil E. The virtual image position changing unit 31 temporarily stops the optical pupil E when at least a part of the background B overlapping the virtual image V approaches the optical pupil E side from the reference virtual image position D0 and then moves away from the optical pupil E side. It is desirable to change the gaze virtual image position changed so as to approach the reference side so that it approaches the reference virtual image position D0 within a range closer to the optical pupil E side than the background B. When the background is farther away from the optical pupil E than the reference virtual image position D0, the gaze virtual image position is changed to the reference virtual image position D0 at the maximum. Accordingly, in the example of FIG. 6, the gaze virtual image distance changes in the order of V1, V2, and V1.

  After the background B approaches the optical pupil E side once, the background B may move away from the optical pupil E, for example, when the observer changes the observation direction of the background B to the left or right direction. In such a case, the virtual image position changing unit 31 approaches the reference virtual image position D0 within the range closer to the optical pupil E than the background B by changing the gaze virtual image position once changed so as to approach the optical pupil E side. Since the gaze virtual image position moves away from the optical pupil E, it is possible to reduce the observer's fatigue and burden caused by continuing to gaze at the virtual image at a position close to the optical pupil E, and to observe the virtual image well. Further, by moving the virtual image away from the optical pupil E within a range not exceeding the reference virtual image position D0, the observer can observe a virtual image (however, the angle of view is constant) larger than the virtual image at a position close to the optical pupil E, The virtual image can be easily observed.

  In addition, measurement noise may be included in the measurement result of the measurement sensor of the background distance measurement unit 8 described above. If the gaze virtual image position is changed with respect to the measurement noise, such a change may occur frequently, and if this occurs too frequently, the observer feels tired. Therefore, in order to reduce the influence of measurement noise, it is desirable to change the gaze virtual image position (attention virtual image distance) based on the measurement distance result (for example, average value) for a certain period of time (for example, several seconds).

  The virtual image distance changing unit 33 described above has a higher refractive index than air in the optical path between the LCD 15 and the eyepiece optical system 21 instead of changing the relative distance between the LCD 15 and the eyepiece optical system 21. The gaze virtual image position may be changed by inserting / removing a medium (for example, a prism).

  Note that the change of the gaze virtual image position by changing the gaze virtual image distance is applied not only to the binocular display using the video display units 1R and 1L but also to the one-eye display using one of the video display units. be able to.

(Change of gaze virtual image position (2))
Next, another example of changing the gaze virtual image position will be described. The virtual image position changing unit 31 further includes a convergence angle changing mechanism 36 shown in FIG. 7 in addition to the virtual image distance changing unit 33 described above. Note that the virtual image position changing unit 31 may be configured by the convergence angle changing mechanism 36 alone.

  The convergence angle changing mechanism 36 is a convergence angle changing means for changing the position of the virtual image V by changing the convergence angle. The convergence angle changing unit 9, the LCD 15, and the control unit 35 for controlling them. It is configured. For example, as shown in FIG. 8, based on the control of the control unit 35, the convergence angle changing unit 9 rotates the video display units 1 </ b> R and 1 </ b> L relatively in the horizontal direction with the shaft 9 a (see FIG. 2) as the rotation axis. Thus, the convergence angle can be changed as shown in FIG. In addition, the convergence angle can be changed by changing the video displayed on the LCD 15, which will be described later.

  Here, when the convergence angle is as small as α (°), the position where the display virtual images observed by the left and right eyes overlap is far from the optical pupil E, and as a result, the observer's gaze virtual image position D11 is far. Conversely, when the convergence angle is β (°) larger than α, the position where the display virtual images observed by the left and right eyes overlap each other approaches the optical pupil E, and as a result, the observer's gaze virtual image position D12 becomes close. That is, when the control unit 35 determines that the position of the background B is closer than the gaze virtual image position before the position change from the relationship between the gaze virtual image distance V1 and the background distance B1 (V1> B1), the convergence angle change unit. By rotating the video display units 1R and 1L relatively by 9 and increasing the convergence angle from α to β, it is possible to shift the gaze virtual image position to the near side of the background B (to the optical pupil E side). . Thereby, it is possible to avoid the sense of incongruity by avoiding that the gaze virtual image is embedded in the background B and observed. On the contrary, if the image display units 1R and 1L are rotated by the convergence angle changing unit 9 so that the convergence angle becomes small, the gaze virtual image position can be moved away from the optical pupil E. Note that the shift amount of the virtual image position can be controlled by the change amount of the convergence angle.

  As described above, since the virtual image position changing unit 31 includes the convergence angle changing mechanism 36, the gaze virtual image position can be easily changed by changing the convergence angle in the video display device 1 capable of observation with both eyes. It becomes possible. In particular, for the observer, the change in the convergence angle has a greater influence (priority) on the observation than the change in the gaze virtual image distance (diopter), so the convergence angle is changed without changing the diopter. Thus, the gaze virtual image position can be easily changed. Further, since the convergence angle changing mechanism 36 changes the convergence angle by relatively rotating the video display units 1R and 1L, it is easy to change the convergence angle.

  In addition, the virtual image position changing unit 31 includes both the virtual image distance changing unit 33 and the convergence angle changing mechanism 36 described above, so that the gaze virtual image distance can be observed in the video display device 1 that can be observed with both eyes. Both the angle of convergence and the angle of convergence can be changed, and the gaze virtual image position can be changed reliably. Also, changing the gaze virtual image distance changes the focus, but changing the convergence angle does not change the focus. However, by changing both the gaze virtual image distance and the convergence angle by changing the convergence angle by rotating the video display units 1R and 1L simultaneously with the diopter change by the shift of the LCD 15, the position after the position change is changed. Since the virtual image is in focus, the eyestrain of the observer can be reduced.

  Incidentally, FIG. 10 schematically shows another example of changing the convergence angle. In the figure, the convergence angle changing mechanism 36 displays both the images to be displayed on the LCDs 15 of the image display units 1R and 1L by shifting them in the direction corresponding to the eye width (left and right direction, horizontal direction). The convergence angle is changed. Even with such a method, it is possible to easily change the convergence angle when observing a virtual image of each display image with both eyes.

  That is, the convergence angle can be easily changed by causing the video display units 1R and 1L to display an image obtained by shifting the original image in the left-right direction by image processing. For example, it is assumed that the same image (original image) IR / IL is displayed on each LCD 15 of the video display units 1R and 1L at the gaze virtual image position D11. By the image processing, left and right display images IR ′ and IL ′ shifted from the original image in the horizontal and horizontal directions toward the center of the pupil are generated and displayed on each LCD 15. In this case, the observer moves the gazing point to the position where the left and right images overlap, so that the gazing virtual image position can be changed to D12.

  In other words, when the control unit 35 determines that the position of the background B is closer than the gaze virtual image position before the position change from the relationship between the gaze virtual image distance V1 and the background distance B1 (V1> B1), the display is displayed on each LCD 15. The convergence angle can be increased from α to β by shifting and displaying both of the images to be displayed in a direction corresponding to the eye width in a direction toward the center of the pupil. As a result, even when the background B approaches, the gaze virtual image position is shifted to the front of the background B (to the optical pupil E side), so that it is avoided that the gaze virtual image is embedded in the background B and observed. And the discomfort caused by the observation can be resolved. Conversely, if the left and right display images are shifted in the direction away from the pupil, the gaze virtual image position can be moved away. Note that the shift amount of the gaze virtual image position can be controlled by the shift amount in the direction corresponding to the eye width direction of the original image.

  Although both the left and right display images are shifted here, the same effect as described above can be obtained by shifting only one of the display images.

(Warning when background approaches)
By the way, the video display device 1 described above may be configured to include a warning unit that issues a warning to the observer when the background position is closer to the optical pupil side than the gaze virtual image position. Such warning means can be constituted by, for example, the control unit 35 and the LCD 15. For example, if the control unit 35 determines that the background position is closer than the gaze virtual image position based on the relationship between the gaze virtual image distance and the background distance, as illustrated in FIG. 11, a display that prompts a warning on the LCD 15 (for example, “WARNING” Or display an image obtained by combining a display image and an image prompting a warning (for example, “WARNING!”), As shown in FIG.

  Further, as shown in FIG. 13A, a light emitting unit (for example, LED) 41 is disposed in the vicinity of the LCD 15, and the control unit 35 causes the light emitting unit 41 to emit light simultaneously with displaying an image on the LCD 15. As shown in FIG. 13B, the peripheral portion of the display virtual image may be brightened to prompt a warning. In this case, the control unit 35, the LCD 15, and the light emitting unit 41 constitute the warning means. Note that the driver circuit unit and the apparatus main body may be vibrated by a vibration member to prompt a warning.

  By such warning means, it is possible to warn the observer that there is a possibility that a sense of incongruity may occur if the virtual image is continuously observed while the background is close to the optical pupil side, and avoidance of this state can be promoted.

  Further, the video display device 1 described above may be configured to include a control unit that performs control for interrupting display of video on the LCD 15 when the background position is closer to the optical pupil side than the gaze virtual image position. Such control means can be configured by the control unit 35. By the above control, when the background position is close to the optical pupil side, it is possible to eliminate the possibility that the viewer may feel discomfort by interrupting the video display. In addition, this method can reproduce the actual situation where a distant image is blocked by a nearby image by using a virtual image as a distant image and interrupting the virtual image display.

(Supplement)
Of course, it is possible to configure the video display device 1 and thus the HMD by appropriately combining the above-described configurations. For example, even if the background is partly closer to the optical pupil side than the virtual image, or after that, when part of the background is further away from the optical pupil, the convergence angle can be changed or the display image can be shifted by rotating the display unit. It is also possible to change the convergence angle, and it is possible to change such a convergence angle in stages.

  The video display device 1 described above can be applied to, for example, a head-up display (HUD).

  The video display device of the present invention described above can also be expressed as follows. That is, the video display device of the present invention includes a display element that displays video, and an eyepiece optical system that guides video light from the display element to an optical pupil, and a background with a virtual image of the display video at the position of the optical pupil. Display-through image display device, and a gaze virtual image position changing unit that changes the position of the virtual image that the observer gazes at, and a gaze virtual image that stores a distance from the optical pupil of the virtual image before and after the position change A distance storage means; and a background distance measuring means for measuring a distance from the optical pupil of the background or the image display device that is observed overlapping with the virtual image, and the gaze virtual image position changing means is stored in the gaze virtual image distance storage means. Based on the stored distance of the virtual image before the position change and the measurement result of the background distance measuring means, at least a part of the background is closer to the optical pupil than the position of the virtual image before the position change. When it is determined that it is Ku, a position of the virtual image may be configured to change so as to approach the optical pupil side than at least a portion of the background.

  In the video display device of the present invention, the gaze virtual image distance storage unit stores a reference virtual image position serving as a reference for the position of the virtual image, and the gaze virtual image position change unit includes at least a part of a background overlapping the virtual image. After moving closer to the optical pupil side than the reference virtual image position and then moving away from the optical pupil side, the virtual image position that has been changed so as to approach the optical pupil side once is at least part of the background It may be changed so as to approach the reference virtual image position within a range closer to the optical pupil side.

  An image display apparatus according to the present invention includes a display element for displaying an image and an eyepiece optical system that guides image light from the display element to an optical pupil, and at the position of the optical pupil, a background is displayed with a virtual image of the display image. A background distance measuring means for measuring a distance from a background image display device that is observed by being overlapped with a virtual image observed by an observer, and a distance from the optical pupil at the position of the fixation virtual image And warning means for giving a warning to the observer based on the measurement result of the background distance measuring means, the warning means that at least a part of the background is closer to the optical pupil side than the gaze virtual image position A configuration may be used in which a warning is given to the observer when the determination is made.

  An image display apparatus according to the present invention includes a display element for displaying an image and an eyepiece optical system that guides image light from the display element to an optical pupil, and at the position of the optical pupil, a background is displayed with a virtual image of the display image. A background distance measuring means for measuring a distance from a background image display device that is observed by being overlapped with a virtual image observed by an observer, and a distance from the optical pupil at the position of the fixation virtual image And control means for controlling the display of the image on the display element based on the measurement result of the background distance measuring means, wherein the control means is such that at least a part of the background is closer to the optical pupil than the gaze virtual image position. The display may be interrupted when it is determined that the display element is close to.

  The present invention is applicable to HMD and HUD.

1 is a perspective view schematically showing a positional relationship among an optical pupil, a virtual image, and a background in a video display device according to an embodiment of the present invention. (A), (b), and (c) are respectively a plan view, a front view, and a side view showing a schematic configuration of an HMD to which the video display device is applied. It is sectional drawing which shows the schematic structure of the said video display apparatus. It is explanatory drawing which shows the structure of the principal part of the said video display apparatus. In the said video display apparatus, it is explanatory drawing which shows the change of the gaze virtual image position when a part of background which overlaps with a virtual image becomes near the optical pupil side rather than a virtual image. In the said video display apparatus, after a background approaches the optical pupil side once, it is explanatory drawing which shows a mode that it leaves | separates from an optical pupil. It is a block diagram which shows the schematic structure of the convergence angle change means which the gaze virtual image position change means of the said video display apparatus has. It is a top view of said HMD which changed the convergence angle. It is explanatory drawing which shows an example of a change of a convergence angle typically. It is explanatory drawing which shows typically the other example of the change of a convergence angle. It is explanatory drawing which shows an example of the warning display in LCD of the said video display apparatus. It is explanatory drawing which shows the other example of the warning display in LCD of the said video display apparatus. (A) is a top view which shows one structural example of a warning means, (b) is explanatory drawing which shows typically an example of the virtual image displayed.

Explanation of symbols

1 video display device 1R video display unit (right eye display unit)
1L video display unit (display unit for left eye)
2 Supporting means 8 Background distance measuring unit (background distance measuring means)
9 Convergence angle changing unit (convergence angle changing means)
15 LCD (display element)
21 Eyepiece optical system 22 Eyepiece prism (optical member)
24 Optical elements (hologram optical elements)
31 Virtual image position changing unit (gazing virtual image position changing means)
33 Virtual image distance changing unit (virtual image distance changing means)
34 Drive unit (gazing virtual image position changing means, virtual image distance changing means)
35 Control unit (gazing virtual image position changing means, virtual image distance changing means, convergence angle changing means)
36 Convergence angle changing mechanism (convergence angle changing means)
E Optical pupil

Claims (13)

A video display device that includes a display device for displaying video and an eyepiece optical system that guides video light from the display device to an optical pupil, and allows a background to be observed through a virtual image of the display video at the position of the optical pupil. And
Gaze virtual image position changing means for changing the position of the gaze virtual image;
A background distance measuring means for measuring the distance from the image display device of the background that is observed overlapping the gaze virtual image,
The gaze virtual image position changing means is configured such that at least a part of the background is closer to the optical pupil than the gaze virtual image position based on the distance of the gaze virtual image position from the optical pupil and the measurement result of the background distance measurement means. An image display device characterized by changing the gaze virtual image position so as to be closer to the optical pupil side than at least a part of the background when it is determined that the distance is close.   The gaze virtual image position changing means includes gaze virtual image distance changing means for changing the gaze virtual image position by changing the distance of the gaze virtual image from the optical pupil. The video display device described. A left-eye display unit and a right-eye display unit corresponding to the left and right eyes of the observer,
Both of the display units include the display element and the eyepiece optical system,
The video display device according to claim 1, wherein the gaze virtual image position changing unit includes a convergence angle changing unit that changes the gaze virtual image position by changing a convergence angle.   The gaze virtual image position changing unit further includes a gaze virtual image distance changing unit that changes the gaze virtual image position by changing a distance of the gaze virtual image from the optical pupil. The video display device described in 1.   The gaze virtual image distance changing unit changes a distance of the gaze virtual image from the optical pupil by changing a relative distance between the display element and the eyepiece optical system. The video display device described.   5. The video display device according to claim 3, wherein the convergence angle changing unit changes the convergence angle by relatively rotating the display unit for the left eye and the display unit for the right eye.   The convergence angle changing means is configured to display at least one of the images to be displayed on the display elements of the left-eye display unit and the right-eye display unit by shifting the image in a direction corresponding to the eye width of the observer. The video display device according to claim 3, wherein the video display device is changed.   The gaze virtual image position changing means determines that the gaze virtual image position is a part of the background when the gaze virtual image position is determined to be closer to the optical pupil side than the gaze virtual image position. The video display device according to claim 1, wherein the video display device is changed so as to be closer to the optical pupil side.   9. The video display device according to claim 1, wherein the gaze virtual image position changing unit changes the gaze virtual image position in a stepwise manner.   The gaze virtual image position changing means is configured such that at least a part of the background overlapping the gaze virtual image is closer to the optical pupil side than a reference virtual image position set in advance as a reference for the gaze virtual image position, and then opposite to the optical pupil. The position of the gaze virtual image that has been changed so as to approach the optical pupil side once away from the camera is changed so as to approach the reference virtual image position within a range closer to the optical pupil side than at least a part of the background. The video display device according to claim 1, wherein: The eyepiece optical system is
An optical member that guides the image light from the display element by totally reflecting the light inside;
11. A volume phase reflection type hologram optical element that diffracts and reflects the image light guided in the optical member and guides the image light to an optical pupil. The video display device described.   12. The image display device according to claim 11, wherein the hologram optical element has an axially asymmetric positive optical power. The video display device according to any one of claims 1 to 12,
A head-mounted display comprising: support means for supporting the video display device in front of an observer's eyes.

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