JP5017817B2 - Virtual image optical device - Google Patents

Description

The present invention relates to a virtual image display apparatus using the spatial light modulating optical equipment.

In an image display device such as a projection display device, a configuration using a tapered light pipe is proposed as an illumination optical device for a spatial light modulation unit that modulates an image (see, for example, Patent Documents 1 to 3).
With reference to FIG. 18, an example of an illumination optical device using a conventional tapered light pipe described in Patent Document 1 will be described. As shown in the schematic configuration diagram of FIG. 18, this illumination optical apparatus includes a light source 1506, a reflecting mirror 1508, and a tapered light pipe 1502, and a reflector 1512 that reflects light 1501 emitted from the light source 1506 forward. For example, a concave reflecting mirror 1508 that reflects 1501 and tapered light pipes 1502 and 1516 are formed.
In such a configuration, the light 1501 emitted from the light source 1506 is reflected by the reflecting mirror 1508, and an image of the light source 1506 is formed near the input end 1507 of the tapered light pipe 1502 by the reflecting mirror 1508. ing. The light beam incident on the tapered light pipe 1502 exits from the exit surface 1503 formed in a lens shape with a reduced numerical aperture (Numerical Aperture: NA), and then enters another light pipe 1516 that is arranged.
With this illumination optical device, the light beam emitted from the light source is converted into a desired divergence angle and area to improve efficiency and uniformity of illuminance.
Other conventional examples of illumination optical devices using a tapered light pipe are disclosed in the above-mentioned Patent Documents 2 and 3, etc., but in any case, an optical fiber is provided between the tapered light pipe and the spatial light modulator. And a polarization converter are arranged to further improve uniformity and illumination efficiency.

  The illumination optical devices according to these conventional examples are mainly used for projection type image display devices, and are configured to re-image the image of the spatial light modulator illuminated by the illumination optical device on the screen. Yes. Alternatively, after the light pipe is emitted, it is used as a configuration in which the spatial light modulator is not directly illuminated but is incident on the optical fiber or another light pipe again to further improve the uniformity.

US Patent Application Publication No. 2005/0047723 U.S. Pat.No. 6,739,726 US Patent Application Publication No. 2003/0021530

The conventional illumination optical device described above is suitable when used in a projection-type image device as described above, but has the following drawbacks as an illumination optical device for a virtual image display device.
(1) In particular, when applied to an image display device that is required to be small and light, such as a head mounted display (HMD), after the tapered light pipe, it is further necessary to improve the uniformity. If the light pipe or the optical fiber is used, the entire lighting device becomes large, which is not preferable.
(2) The illumination light emitted from the exit surface of the tapered light pipe has a relatively large luminance non-uniformity in the exit NA as it is. This non-uniformity is not a problem in the case of a projection-type image display device that re-images light emitted from an arbitrary pixel of the spatial light modulator on the screen, but in the case of a virtual image display device, This is not preferable because it causes a luminance change when the pupil position of the person moves.

  The reason for the above (2) will be described with reference to FIG. 19 and FIGS. First, as shown in FIG. 19, an optical system of a projection display device in which a tapered light pipe 20, a spatial light modulator 60, and a projection lens 170 are arranged on the optical axis of light emitted from the light source 10 will be described. To do. In this case, the light emitted from the light source 10 is emitted by adjusting the numerical aperture NA by the tapered light pipe 20 and is incident on the spatial light modulation unit 60 such as a transmissive liquid crystal panel. Modulated. The light emitted from the spatial light modulator 60 is projected onto the screen 180 by the projection lens 170. In this case, the variation in the luminous flux (or light energy) within the radiation angle of the image display light emitted from one point of the spatial light modulator 60 is re-imaged on the screen 180, and thus is not recognized by the observer. It doesn't matter.

On the other hand, when the light pipe is applied to the virtual image coupling optical system as described above, the following problems occur. That is, in this case, as shown in FIGS. 20A to 20C, the light source 10, the light pipe 20, the spatial light modulator 60, and the eyepiece lens 270 are arranged on the optical axis, and the image display light modulated by the spatial light modulator 60 is obtained. Let us consider an optical system that observes the image with the pupil 80 through the eyepiece 270.
At this time, as shown in FIG. 20A, the variation in the luminous flux (or light energy) within the radiation angle of the image display light emitted from one point of the spatial light modulation unit 60 is as follows. If it moves as shown by arrow a in FIG. 20 or rotates as shown by arrow b in FIG. 20C, it will be recognized as a variation in brightness.
For such a problem, for example, if the total length of the tapered light pipe is increased, this non-uniformity tends to be improved. In this case, however, the apparatus becomes larger and the above-mentioned head-mounted display or the like is used. If used, it is not desirable.
Therefore, in order to improve such non-uniformity, it is desirable to illuminate the spatial light modulator with a relatively large illumination numerical aperture by using, for example, a diffusion plate.

On the other hand, when using, for example, a liquid crystal panel as a spatial light modulation unit of a virtual image display device or a projection type image display device, a reflective liquid crystal panel that is superior in light use efficiency to a transmissive liquid crystal panel in order to increase the light use efficiency Is required to be used.
When using such a reflective spatial light modulator, it is necessary to interpose an optical component such as a polarization beam splitter between the exit surface of the illumination optical system and the spatial light modulator. It becomes relatively large. Therefore, when the reflective spatial light modulation unit is illuminated with a relatively large illumination numerical aperture in order to maintain the uniformity of luminance, such as when used in the virtual image coupling optical system as described above, this light is used. The problem is that the pipe becomes long.

This will be described with reference to FIG. FIG. 21 shows a case where the light pipe 20, the polarization beam splitter 50, and the reflective spatial light modulator 60 are arranged on the optical path of the light emitted from the light source 10. Then, the illumination condition is a telecentric state, that is, a state in which the central ray is perpendicularly incident on the spatial light modulator, and the illumination half-value angle is θd. Further, the width of the spatial light modulator 60 where the illumination light is incident is Wd, and the distance from the light pipe 20 is Ls. From this, the width W1h of the exit surface 22 of the light pipe 20 is
W1h = Wd + 2Ls × tan (θd)
It becomes.

  As described above, in the case of a reflective spatial light modulator that includes PBS or the like, the distance Ls between the exit surface 22 of the light pipe 20 and the spatial light modulator 60 must be longer than that of the transmissive spatial light modulator. In addition, it can be seen that when the illumination numerical aperture NA is large, the illumination half-value angle θd is also increased, and as a result, the width W1h of the exit surface 22 of the light pipe 20 is increased.

On the other hand, the length of the light pipe 20 itself cannot be reduced. A light source 10 such as an LED (light emitting diode) or a laser is disposed in the vicinity of the incident surface 21 of the light pipe 20, and illumination light is taken into the light pipe 2 from here. The illumination light taken into the light pipe 20 reaches the exit surface 22 while undergoing total internal reflection at the side surface 23 of the light pipe 20. In the light pipe, the uniformity of the luminance of the illumination light emitted from the exit surface 22 tends to improve as the amount of light and the number of times of total internal reflection increase.
The illumination light emitted from the light source 10 has a radiation angle of 90 degrees or more. Therefore, the smaller the inclination angle θh of the side surface of the light pipe 20, the greater the number of reflections. Now, since the width W2h of the incident surface 21 of the light pipe 20 is substantially the same as the width of the light source 10, it is assumed that the inclination angle θh of the side surface 22 is suppressed to a constant value (θh) in order to maintain the uniformity of luminance. As shown by the following equation, the length Lh of the light pipe 20 is determined by the width W1h of the exit surface.
Lh = (W1h−W2h) / (2 × tan (θh))

From this, it can be seen that the length Lh of the light pipe 20 increases as the emission surface width W1h increases, that is, when the illumination numerical aperture NA is increased.
In the example described above, the illumination condition is telecentric. However, when the chief ray of the illumination light incident on the periphery of the reflective spatial light modulator 60 is tilted, the length of the light pipe 20 depends on the tilt direction. Lh is affected.
Thus, in an optical device using a reflective spatial light modulation unit, if the light use efficiency is increased when illuminating the spatial light modulation unit with a large numerical aperture, the light pipe will be lengthened, and the entire device will be increased. It turns out that it becomes disadvantageous for miniaturization.

In view of the above problems, an object of the present invention is to maintain the efficiency of illumination and the uniformity of luminance without increasing the size of a light pipe, and to reduce the size of the entire spatial light modulation device. Further, by using a spatial light modulator device of the present invention, without lowering the Oite luminance unevenness and brightness virtual image display equipment, and an object thereof is to enable miniaturization.

A virtual image display device according to the present invention is a virtual image display device having a spatial light modulation optical device and a virtual image imaging optical system that guides a display image of the spatial light modulation optical device to a pupil of an observer, the spatial light modulation optical device Has a plurality of light sources, a plurality of light pipes, a spatial light modulation unit, and a diffuser plate, and the light sources are arranged in the vicinity of the incident surfaces of the plurality of light pipes, and the spatial light modulation unit has an illumination area thereof The number of light pipes corresponding to the direction in which the width of the illumination area is large is larger than the number of light pipes corresponding to the direction in which the width of the illumination area is small. Made up. The light beam emitted from the light source is incident on the inside of the light pipe from the incident surface, and at least a part of the light beam is totally internally reflected on the side surface and then emitted from the emission surface having a larger area than the incident surface. The light guided to the spatial light modulator and modulated by the spatial light modulator enters the virtual image imaging optical system. The virtual image forming optical system includes a collimating optical system that converts light beams emitted from each pixel of the spatial light modulation unit into parallel light beam groups having different traveling directions, and a parallel light beam group that is incident. The light guide plate is configured to be propagated by being totally reflected multiple times in the left-right direction with respect to the observer's pupil without being reflected in the vertical direction with respect to the pupil, and then emitted toward the observer's pupil. The light guide plate includes a first reflective volume hologram grating that diffracts and reflects the parallel light beam group in the incident region of the parallel light beam group so as to satisfy the internal total reflection condition in the light guide plate while the parallel light beam group remains, and the emission of the parallel light beam group A second reflective volume hologram grating that diffracts and reflects so that the parallel light beam group is emitted from the light guide plate as the parallel light beam group in the region is provided. The diffusion plate is provided between the plurality of light pipes and the spatial light modulator, and has a diffusivity in which the horizontal diffusion angle with respect to the observer's pupil is larger than the vertical diffusion angle with respect to the observer's pupil. The vertical diffusion angle is set to such a size that the parallel light flux incident on the virtual image forming optical system does not expand in the vertical direction.

According to the virtual image optical device of the present invention described above, a plurality of light sources and a plurality of light pipes of the spatial light modulation optical device are provided, and the number of arrangements is arranged in accordance with the size of the illumination area of the spatial light modulation unit. Therefore, the luminance unevenness can be suppressed, the luminance can be made uniform, and the decrease in light utilization efficiency can be suppressed regardless of the illumination numerical aperture. Even when the distance between the light pipe and the spatial light modulator is relatively large and the illumination numerical aperture needs to be large, uniform illumination can be achieved without increasing the length of the light pipe. Thus, the overall size of the apparatus can be reduced. Therefore, it is possible to realize a virtual image optical apparatus that is excellent in light use efficiency and uniformity in illumination luminance, while being small and light.

As described above, according to the present invention, by there use efficiency of illumination with respect to the spatial light modulator, the spatial light modulation optical device capable to miniaturize retaining the uniformity of brightness, less luminance unevenness it is possible to provide a relatively compact virtual image display equipment.

Examples of the best mode for carrying out the present invention will be described below, but the present invention is not limited to the following examples.
First, embodiments of the spatial light modulation optical device according to the present invention will be described.

[1] First Embodiment The first embodiment of the spatial light modulation optical device according to the present invention will be described with reference to FIG. FIG. 1A is a schematic plan configuration diagram viewed from the top surface of the spatial light modulation optical device, and FIG. 1B is a schematic side configuration diagram of the spatial light modulation optical device. As shown in FIGS. 1A and 1B, this spatial light modulation optical device includes a light source 10 composed of LEDs and the like, a multi-light pipe 20 composed of a plurality of tapered light pipes 20a, 20b and 20c, and an optical lens 30 such as a Fresnel lens. , A diffusion plate 40, a polarizing beam splitter 50, a reflective spatial light modulator 60 such as a reflective liquid crystal panel or DMD (Digital Micro-mirror Device).
In addition, the spatial light modulator 60 indicated by a broken line in FIG. 1A has different illumination areas in one direction (x direction) and the other direction (y direction). In this example, the multi light pipe 20 The number of arrays in the long side direction (x direction) where the width of the general illumination area is large is 3, and the number of arrays in the short side direction (y direction) is small where the width of the illumination area is small. In FIG. 1B, an arrow y0 indicates a direction corresponding to the short side direction (y direction) of the light beam before being reflected by the polarization beam splitter 50.

In such a configuration, the illumination light emitted from the light source 10 is incident from the incident surface 21 having a relatively small area of each of the light pipes 20a to 20c of the multi-light pipe 20, and some of the light beams have undergone total internal reflection. Thereafter, the light exits from the exit surface 22 having a larger area than the entrance surface 21.
In the present embodiment, the exit surface 22 is a cylindrical surface having a concave curvature in the short side direction (y direction) of the spatial light modulator 60.

Illumination light emitted from the exit surface 22 of the multi-light pipe 20 is a uniaxial Fresnel lens having positive power only in the x direction (corresponding to the long side direction of the spatial light modulator 60) in FIG. After being diffused by the diffusing plate 40 through the optical lens 30 composed of the optical lens 30, the light enters the optical surface 51 of the polarizing beam splitter 50. Subsequently, the illumination light Li is reflected by the polarization separation film 52 as its S-polarized component is indicated by an arrow S, and the P-polarized component is transmitted as indicated by an arrow Pt. The reflected S-polarized light component is emitted from the optical surface 53 of the polarization beam splitter 50 and illuminates the reflective spatial light modulator 60.
The illumination light mainly having the S-polarized light component incident on the reflective spatial light modulator 60 is modulated in polarization state for each pixel of the reflective spatial light modulator 60, and the ratio between the P-polarized component and the S-polarized light component is controlled. For example, it is reflected as display light corresponding to image information. The illumination light modulated and reflected by the reflective spatial light modulation unit 60 is incident on the polarization beam splitter 50 again, and the P-polarized light component is transmitted through the polarization separation film 52, as indicated by an arrow P. The light is emitted from the optical surface 54 to the outside. The S-polarized component is returned to the optical surface 51 side.

  As described above, the spatial light modulation optical device according to the present embodiment includes a plurality of light sources, a plurality of light pipes, and a spatial light modulation unit, and further arranges an optical lens and a diffusion plate between them as necessary. The illumination light having a large numerical aperture NA emitted from the light source is first converted into illumination light having a predetermined numerical aperture NA by equalizing the luminance with a plurality of light pipes arranged in one row, for example. By using a multi-light pipe, it is possible to avoid an increase in the size of the apparatus. In this example, the chief ray angle of the illumination light is controlled in an optical lens such as a Fresnel lens, and finally, readjustment including anamorphic diffusion angle and reduction of luminance unevenness within the radiation angle are performed by a diffusion plate. Is going.

In such a spatial light modulation optical device, a ray trace was simulated. The results are shown in FIGS. 2A and 2B. FIG. 2A shows a ray trace in the x direction and FIG. 2B shows a ray trace in the y direction. 2A and 2B, parts corresponding to those in FIGS. 1A and 1B are denoted by the same reference numerals, and redundant description is omitted.
In this simulation, the diffusion action by the diffusion plate 40 and the reflection by the polarization separation film 52 of the polarization beam splitter 50 are not reflected. In this embodiment, the light source 10 made of LEDs is optically adhered to the incident surface 21 of the multi-light pipe 20 in order to increase the light utilization efficiency.

Further, in the y direction, which is the short side direction of the spatial light modulator 60, the single light pipe of the multi-light pipe 20 is entirely illuminated, and the emission surface 22 is a concave cylindrical surface. Therefore, the angle at which the illumination light is incident on the reflective spatial light modulator 60 becomes more distant from the vertical state (telecentric state) as it goes to the peripheral region of the reflective spatial light modulator 60, and the reflective spatial light modulator It falls to the center side of 60.
On the other hand, with respect to the x direction, which is the long side direction of the spatial light modulator 60, the three light pipes of the multi-light pipe 20 are arranged in a line and are condensed by the optical lens 30 including a convex uniaxial Fresnel lens. Therefore, the illumination is closer to the telecentric illumination than in the y direction and has a larger numerical aperture NA. In this manner, the spatial light modulation optical device 100 according to the present embodiment has the spatial light modulation unit 60 in the x direction and the y direction with the illumination conditions shown in Table 1 and Table 2 below, respectively. It was set as the structure which illuminates.

In Tables 1 and 2 above, the display light beam is emitted from the reflective spatial light modulator 60, and the light beam passing through the center of each angle of view at the image height position from the optical axis. A principal ray angle that is an angle from the axis and an upper ray angle and a lower ray angle that are spread angles of the emitted light are respectively shown.
As can be seen from Table 1 above, the spread angle is about ± 20 degrees in the x direction, whereas the spread angle is about ± 5 degrees in the y direction. That is, the numerical aperture NA is large in the x direction, and the numerical aperture NA is small in the y direction.
That is, in this case, the numerical aperture of the emitted light and the emission angle of the principal ray are different from each other in one direction and the other direction, that is, the x direction and the y direction, respectively. The case where asymmetrical illumination is performed in the long side direction and the short side direction is shown.
This illumination condition is a suitable condition in the virtual image display device described in detail in the fifth embodiment example below.
Illumination under different conditions.

FIG. 3 shows the illuminance distribution of illumination to the spatial light modulator 60 under such illumination conditions. As can be seen from FIG. 3, even though the illumination is performed with a larger numerical aperture in the x direction, the illuminance distribution is substantially up to the periphery of the rectangular region corresponding to the illumination region of the spatial light modulator 60. It can be seen that uniformity is maintained over the entire surface.
In this case, since the spatial light modulator such as a reflective liquid crystal panel is used, the light use efficiency can be kept high.

On the other hand, as a comparative example, an example of a spatial light modulation optical device when one light pipe is used is shown in the schematic configuration diagram of FIG. In this comparative example, a Fresnel lens 220 and a diffuser plate 230 are disposed between the light pipe 120 and the polarization beam splitter 240.
Also in this spatial light modulation optical device, spatial light modulation is performed with the illumination conditions shown in Table 1 and Table 2 in the long side direction (x direction) and the short side direction (y direction) of the spatial light modulation unit 60, respectively. It was set as the structure which illuminates a part.

  As shown in FIGS. 4A and 4B, when only one light pipe 120 is used as described above and the lighting conditions are different in the long side direction and the short side direction of the spatial light modulator 60, the light pipe is used. It can be seen that the width W1h of the exit surface of the shape 120 is greatly different between the direction along the long side direction and the direction along the short side direction. In this case, since the length of the light pipe 120 is determined by the relatively large width W1h in the direction along the long side direction of the spatial light modulator 60, the peripheral luminance is 60% of the central luminance. If designed based on the standard, the total length Lh becomes long as shown in FIG. 4B. Further, the curved shape of the exit surface in the x direction is a special shape having a very small radius of curvature as shown in FIG. 4A.

The result of simulating the trace of the emitted light from the light source at this time is shown in FIGS. 5A and 5B. 5A shows a ray trace in the x direction, and FIG. 5B shows a ray trace in the y direction.
The luminance distribution in this case is shown in FIG. As is clear from FIG. 6, it is clear that the luminance is lowered in the peripheral portion when one light pipe is used.
From these results, in the above-described first embodiment, the length of each light pipe itself can be reduced compared to the case where one light pipe is used in this way, and the luminance unevenness is also reduced. It can be seen that can be improved.
In particular, in the present embodiment, it is possible to uniformly maintain the luminance distribution in this way, although it is a case where a reflective spatial light modulator having high light utilization efficiency is provided.

  In addition, by providing the multi-light pipe 20, the numerical aperture of the light beam applied to the spatial light modulator 60 can be made sufficiently large without causing an increase in the size of the apparatus. Accordingly, for example, when the spatial light modulation optical device of the present invention is applied to the virtual image display device described with reference to FIGS. 20A to 20C described above, the necessary numerical aperture NA is obtained and the uniformity is sufficient, as described above. In the case of observing a virtual image, it is possible to avoid a change in brightness due to pupil movement or rotation.

In this case, there is also an effect that the illumination optical system can be thinned by disposing a Fresnel lens as an optical lens for adjusting the emission angle between the multi-light pipe 20 and the spatial light modulator 60. If the Fresnel lens is an anamorphic lens, the light use efficiency may be higher. In this case, two Fresnel lenses in one direction with different pitches (that is, functionally cylindrical lenses) are arranged orthogonally. May be.
Furthermore, as described above, when it is necessary to change the numerical aperture NA of illumination in two orthogonal directions (for example, the above-described x direction and y direction), a diffusion plate having different diffusivities in the two orthogonal directions is used as the diffusion plate. It may be used.

[2] Second Embodiment Next, a second embodiment of the spatial light modulation optical device according to the present invention will be described with reference to FIG. 7A and 7B, parts corresponding to those in FIGS. 1A and 1B are denoted by the same reference numerals. The spatial light modulation optical apparatus according to the present embodiment includes a light source 10 made of an LED or the like, a multi-light pipe 20 made up of light pipes 20a to 20c, a diffuser plate 40, a polarization beam splitter 50, and a reflective spatial light modulation unit 60. Has been. In this example, the light pipes 20a to 20c are arranged in a row with respect to the x direction, which is the long side direction of the spatial light modulator 60, and, for example, the central part (need to be the center of the spatial light modulator 60 in the x direction). An example in which the optical axis of the emitted light is inclined is shown. Also in this example, the exit surface 22 of each of the light pipes 20a to 20c is a cylindrical surface having a concave curvature in the short side direction (y direction) of the spatial light modulator 60.

In this spatial light modulation optical device 100, the illumination light emitted from the light source 10 is incident from the incident surface 21 having the smaller area of the multi-light pipe 20, and after a part of the light rays have undergone total internal reflection, 22 injects. Then, after being appropriately diffused by the diffusion plate 40 disposed subsequently, the light enters the polarizing beam splitter 50 from its optical surface 51. Subsequently, the S polarization component of the illumination light is reflected by the polarization separation film 52 and the P polarization component is transmitted. The reflected S-polarized light component is emitted from the optical surface 53 of the polarization beam splitter 50 and illuminates the reflective spatial light modulator 60.
The illumination light mainly having the S-polarized light component incident on the reflective spatial light modulator 60 is modulated in polarization state for each pixel of the reflective spatial light modulator 60, and the ratio between the P-polarized component and the S-polarized light component is controlled. And reflected. The illumination light reflected by the reflective spatial light modulator 60 is incident on the polarization beam splitter 50 again, the P polarization component is transmitted through the polarization separation film 52, and the S polarization component is returned to the optical surface 51 side. It is.

8A and 8B are ray trace diagrams of the spatial light modulation optical device 100. FIG. In this example as well, as in the first embodiment described above, the illumination conditions shown in Table 1 and Table 2 above are used. FIG. 8A shows the ray trace in the x direction and FIG. 8B shows the ray trace in the y direction. . In this example, the diffusion effect by the diffusion plate and the reflection by the polarization separation film 52 of the polarization beam splitter 50 are not reflected.
In this embodiment, the light source 10 made of LEDs is optically adhered to the incident surface 21 of the multi-light pipe 20 in order to increase the light utilization efficiency.
Further, in the y direction, only one individual light pipe of the multi-light pipe 20 illuminates the whole, and the exit surface 22 is a concave cylindrical surface, so that the periphery of the reflective spatial light modulator 60 is The angle at which the illumination light is incident on the reflective spatial light modulator 60 becomes farther away from the vertical state (telecentric state) and falls toward the center of the reflective spatial light modulator 60 as it goes into the region.

On the other hand, with respect to the x direction, the three light pipes of the multi-light pipe 20 are arranged in a line and arranged to draw an arc toward the spatial light modulator 60, so the first embodiment described above. As described above, the illumination light beam efficiently illuminates the spatial light modulator 60 even though there is no optical lens such as a uniaxial Fresnel lens between the multi-light pipe 20 and the polarization beam splitter 50. Thus, also in the spatial light modulation optical device 100 of the present embodiment, the spatial light modulation unit 60 is illuminated under different conditions in the x direction and the y direction.
The illumination distribution in the spatial light modulator 60 in this case is shown in FIG. From FIG. 9, it can be seen that also in this embodiment example, the uniformity of illuminance is maintained over substantially the entire surface, and the luminance unevenness is suppressed.

  As described above, the spatial light modulation optical device according to the present embodiment includes a plurality of light sources, a plurality of light pipes, and a spatial light modulation unit, and a diffuser plate is disposed between the light source and the light source. The illumination light having a large numerical aperture NA is first converted into illumination light having a predetermined numerical aperture NA by equalizing the luminance with a plurality of light pipes arranged in one row, for example. By using a multi-light pipe, it is possible to avoid an increase in the size of the apparatus.

In this example, the principal ray angle of the illumination light is controlled by the arrangement of the multi-light pipes. That is, in this case, by arranging the plurality of light pipes to be inclined toward the center direction of the spatial light modulator, the number of optical lenses used can be reduced or eliminated, and further reduction in size and weight can be achieved. Have
Also in this case, if it is necessary to change the numerical aperture NA of illumination in two orthogonal directions (for example, the above-described x direction and y direction), a diffusion plate having a different degree of diffusion in the two orthogonal directions is used as the diffusion plate. It may be used.

  By adopting such a configuration, for example, different illumination conditions in the long side direction and the short side direction of the spatial light modulation unit, such as those in Table 1 and Table 2 above, can be easily achieved. Therefore, for example, when applied to a virtual image display device, it is possible to display well without a change in brightness with respect to movement of the pupil.

[3] Third Embodiment Next, with reference to FIGS. 10A and 10B, a third embodiment of the spatial light modulation optical device according to the present invention will be described. The spatial light modulation optical device 100 includes a light source 10 composed of LEDs or the like, a multi-light pipe 20 composed of six light pipes, a diffusion plate 40, a polarization beam splitter 50, and a reflective spatial light modulation unit 60. In this embodiment, each exit surface 22 of the multi-light pipe 20 is a cylindrical surface having a concave curvature in the y direction corresponding to the short side direction of the spatial light modulator 60. In this case, the multi-light pipe 20 has three tapered light pipes arranged in the x direction and two in the y direction. Further, an example is shown in which these six tapered light pipes are all tilted in the central direction of the spatial light modulator 60 (not necessarily the center).

  In such a configuration, the illumination light emitted from the light source 10 is incident from the incident surface 21 with the smaller area of the multi-light pipe 20, and after a part of the light rays repeats total internal reflection, the light is emitted from the emission surface 22. To do. Then, after being appropriately diffused by the diffusion plate 40 disposed subsequently, the light enters the polarizing beam splitter 50 from its optical surface 51. Subsequently, the S polarization component of the illumination light is reflected by the polarization separation film 52 and the P polarization component is transmitted. The reflected S-polarized light component is emitted from the optical surface 53 of the polarization beam splitter 50 and illuminates the reflective spatial light modulator 60.

  The illumination light mainly having an S-polarized light component incident on the reflective spatial light modulator 60 is modulated in the polarization state for each pixel of the reflective spatial light modulator 60, and the ratio of the P-polarized component and the S-polarized component is Controlled and reflected. The illumination light reflected by the reflective spatial light modulator 60 is incident on the polarization beam splitter 50 again, the P polarization component is transmitted through the polarization separation film 52, and the S polarization component is returned to the optical surface 51 side. It is.

Even in the spatial light modulation optical device 100 having such a configuration, the luminance unevenness can be suppressed without increasing the size of the light pipe, as in the first and second embodiments. Further, similarly to the second embodiment described above, by arranging the plurality of light pipes to be inclined toward the center direction of the spatial light modulator, the number of optical lenses used can be reduced or eliminated, and Smaller and lighter can be achieved.
Also in this case, different illumination conditions can be easily achieved in the long side direction and the short side direction of the spatial light modulator, for example, as in Tables 1 and 2 above. Therefore, for example, when applied to a virtual image display device, it is possible to display well without a change in brightness with respect to movement of the pupil.

[4] Fourth Embodiment With reference to FIGS. 11A and 11B, a fourth embodiment of the spatial light modulation optical apparatus according to the present invention will be described. In FIGS. 11A and 11B, parts corresponding to those in FIGS. The spatial light modulation optical device 100 includes a light source 10 composed of an LED or the like, a multi-light pipe 20, a diffuser plate 40, a polarization beam splitter 50, and a reflective spatial light modulation unit 60. Moreover, each light pipe of the multi-light pipe 20 shows an example in which the emission surface 22 is a cylindrical surface having a concave curvature in the y direction and is aspherical.
In particular, in this example, each light pipe is a tapered light pipe having a curvature on the side surface 23, and three light pipes in the x direction which is the long side direction of the spatial light modulator 60, and the y direction which is the short side direction. Shows the case where two are arranged. The light pipes are arranged in a line in the x and y directions so as to draw an arc toward the central direction (not necessarily the center) of the spatial light modulator 60.

In such a configuration, the illumination light emitted from the light source 10 is incident from the incident surface 21 with the smaller area of the multi-light pipe 20, and after a part of the light rays repeats total internal reflection, the light is emitted from the emission surface 22. To do. Subsequently, the light is appropriately diffused by the diffusing plate 40 to be arranged, and then enters the polarizing beam splitter 50 from its optical surface 51. Subsequently, the S polarization component of the illumination light is reflected by the polarization separation film 52 and the P polarization component is transmitted. The reflected S-polarized light component is emitted from the optical surface 53 of the polarization beam splitter 50 and illuminates the reflective spatial light modulator 60.
Illumination light mainly having an S-polarized component incident on the reflective spatial light modulator 60 is modulated in polarization state for each pixel of the reflective spatial light modulator 60, and the ratio between the P-polarized component and the S-polarized component is controlled. And reflected. The illumination light reflected by the reflective spatial light modulator 60 is incident on the polarization beam splitter 50 again, the P polarization component is transmitted through the polarization separation film 52, and the S polarization component is returned to the optical surface 51 side. It is.

Even in this case, similarly to the first to third embodiments described above, it is possible to suppress luminance unevenness without increasing the size of the light pipe. Similarly to the second and third embodiments described above, the number of light lenses used can be reduced or unnecessary by arranging a plurality of light pipes inclined toward the center of the spatial light modulator. In addition, further reduction in size and weight can be achieved.
In this example, the side surface of each light pipe has an outwardly convex curved surface, thereby increasing the probability that light emitted from the light source 10 with a relatively large radiation angle will be totally reflected inside each light pipe. Thus, the light use efficiency can be increased.
In this case, the uniformity can be improved by increasing the total number of reflections of light propagating from the entrance surface to the exit surface. Alternatively, when equal uniformity is sufficient, the total length of each light pipe can be shortened, and the apparatus can be reduced in size.
Furthermore, even in this case, different illumination conditions can be easily achieved, for example, in the long side direction and the short side direction of the spatial light modulator, as shown in Tables 1 and 2 above. Therefore, for example, when applied to a virtual image display device, it is possible to display well without a change in brightness with respect to movement of the pupil.

[5] Fifth Embodiment Next, an embodiment of a virtual image display device using the spatial light modulation optical device according to the present invention will be described with reference to FIGS. In this example, an embodiment of a virtual image display device suitable for application to a viewfinder of a video camera, a head-mounted display, or the like is shown.
The virtual image display device 200 of the present example has a light source 10 composed of LEDs or the like, a multi-light pipe 20, first and second, as shown in FIG. Of the uniaxial Fresnel lenses 31 and 32, a diffusing plate 40, a polarizing beam splitter 50, a reflective spatial light modulator 60, a collimating optical system 70 including a finder lens, and a hologram type waveguide 90. Has been. 12A and 12B show a common XYZ coordinate system, with respect to the observer's pupil 80, the horizontal (horizontal) direction is the X direction (corresponding to the long side direction of the spatial light modulator 60), and the vertical (vertical) direction. The direction is shown as the Y direction (corresponding to the short side direction of the spatial light modulator 60), and the depth direction is shown as the Z direction.

  In the present embodiment, the multi-light pipe 20 has a configuration in which three tapered light pipes are arranged in a line in the long side direction of the spatial light modulator 60, that is, in the X direction. In this example, the exit surface 22 of each light pipe is a cylindrical surface having a concave curvature in the Y direction corresponding to the long side direction of the spatial light modulator 60.

  In such a configuration, the illumination light emitted from the light source 10 such as an LED enters from the entrance surface 21 having the smaller area of the multi-light pipe 20, and after a part of the light rays undergoes total internal reflection, the exit surface 22 injects. Then, the light enters the uniaxial Fresnel lenses 31 and 32 that are subsequently arranged. These uniaxial Fresnel lenses 31 and 32 are arranged so that directions having optical powers are orthogonal to each other, and optical powers (that is, focal lengths) are different from each other.

  The illumination light that has passed through the uniaxial Fresnel lenses 31 and 32 is incident on the diffusion plate 40 that is subsequently arranged. This diffusing plate 40 has different diffusivities along the direction in which the uniaxial Fresnel lenses 31 and 32 have optical power. In this embodiment, the diffusibility increases along the direction in which the optical power is large. . Thereby, the light emitted from the diffusion plate 40 is incident on the polarization beam splitter (PBS) 50 with the emission angle and numerical aperture adjusted by the optical characteristics of the Fresnel lenses 31 and 32 and the diffusibility of the diffusion plate 40. The

  The illumination light emitted from the diffusing plate 40 in this way subsequently enters the polarization beam splitter 50 from its optical surface 51, and only the S-polarized component is reflected by the polarization separation film 52 and exits from the optical surface 53. Then, the reflective spatial light modulator 60 is illuminated. The illumination light (image light) modulated and reflected by the reflective spatial light modulator 60 corresponding to the image to be displayed, for example, is reflected by the reflection and the numerical aperture is maintained. And again enters the polarization beam splitter 50, and only the P-polarized component is transmitted by the polarization separation film 52 and exits from the optical surface 54.

  The image light emitted from the optical surface 54 of the polarization beam splitter 50 is viewed by the collimating optical system 70 in the XZ plane shown in FIG. 12A (that is, the emission angle of light emitted from each pixel of the spatial light modulator 60). ) Are different from each other. In the YZ plane orthogonal to this, the parallel light beam group is made into a light beam group having different angles of view and enters the light guide plate 90 as shown in FIG. 12B. 12A shows typical parallel light beams La, Lb and Lc in the XZ plane, and FIG. 12B shows typical parallel light beams LA, LB and LC in the YZ plane.

As shown in FIGS. 12A and 12B, the light guide plate 90 has a thin flat plate configuration, and one end of the optical surface 91 of the optical surfaces 91 and 92 facing the pupil 80 in the depth direction is a collimating optical system. The light exiting from 70 is an incident part 91A, and the other end of the optical surface 91 is an exit part 91B from which light emitted toward the pupil 80 is emitted.
As described above, in this example, the left / right (horizontal) direction is the X direction, and the up / down (vertical) direction is the Y direction. Image display light for displaying information and the like is guided and incident on the pupil 80.
In addition, when this virtual image display device is applied to a head-mounted display (HMD), the illumination optical device, the spatial light modulation unit, and the virtual image display optical system are not arranged above the pupil, and thus in the lateral direction. In the case of arrangement, as compared with the case of arrangement in the upper direction close to the pupil 80, for example, an optical system is not provided in the upper and lower visual fields, so that it is possible to observe the external environment better. On the other hand, in this case, since the distance for guiding the inside of the light guide plate 90 becomes relatively long, the following device is required.

  In the above configuration, the image display light incident on the light guide plate 90 from the incident portion 91A is incident on the first reflective volume hologram grating 93 provided on the optical surface 92 at a position facing the incident portion 91A. In this example, the first reflective volume hologram grating 93 has a uniform hologram surface interference fringe pitch regardless of position.

The light diffracted and reflected by the first reflective volume hologram grating 93 is converted into the optical surface 91 and the light beams La to Lc in the light guide plate 90 in the Z direction of the XZ plane shown in FIG. The light is guided while repeating total reflection between 92 and proceeds in the X direction toward the second reflective volume hologram grating 94 provided at the other end. In FIG. 12A, the light beam La is indicated by a two-dot chain line, Lb is indicated by a solid line, and Lc is indicated by a broken line.
In this embodiment, since the light guide plate 90 is thin and the optical path traveling through the light guide plate 90 is relatively long as described above, as shown in FIG. The total number of reflections up to 94 is different.

More specifically, the number of reflections of the parallel light La incident on the light guide plate 90 while being inclined toward the second reflective volume hologram grating 94 out of the parallel lights La, Lb, and Lc is opposite to that. It is less than the number of reflections of the parallel light Lc incident on the light guide plate 90 at the angle of the direction. That is, since the interference fringe pitches on the hologram surface of the first reflective volume hologram grating 93 are equally spaced, the exit angle diffracted and reflected by the first reflective volume hologram grating 93 is the second reflective volume hologram grating. The parallel light incident while tilting toward 94 is larger than the exit angle of the parallel light incident at an angle opposite to that.
The parallel light of each angle of view that has entered the second reflective volume hologram grating 94 deviates from the total reflection condition due to diffraction reflection, and exits from the light guide plate 90 and enters the observer's pupil 80.

In the light guide plate 90, the Y direction which is the vertical direction with respect to the pupil 80 is not reflected. That is, as shown in FIG. 12B, each of the parallel light beam groups LA to LC repeats reflection in the Z direction which is the depth direction with respect to the pupil 80 in the light guide plate 90, but the Y direction substantially orthogonal to the propagating X direction. Is not reflected and reaches the emission part 91B.
In this case, as described above, since these lights are converged in the Y direction, as shown in FIG. 12B, the second reflection is made with respect to the length of the first reflective volume hologram grating 93 in the Y direction. The reflection diffraction surface of the mold volume hologram grating 94 may have a relatively short configuration.

Differences in the emission angle and numerical aperture of the light beams in the X direction and Y direction described above from the spatial light modulation unit will be described with reference to FIGS. 13 and 14.
In this embodiment of the virtual image display device, since the light guide plate 90 provided with the hologram is used, when the observer's pupil 80 is considered as the exit pupil, the image light from the reflective spatial light modulator 60 is reflected. The emission angle and the numerical aperture NA vary depending on, for example, the long side (X) direction and the short side (Y) direction of the image display area of the spatial light modulation unit such as a reflection type, and also depending on the distance from the center of the image display area. Yes.

That is, as shown in FIG. 13, in the X direction corresponding to the long side direction of the spatial light modulator 60, the light emitted from each pixel has its chief ray as indicated by the alternate long and short dash line. The display surface is substantially perpendicular to the display surface of 60 and close to a telecentric state, and the numerical aperture NA is set relatively large for the reason described later.
On the other hand, as shown in FIG. 14, in the Y direction corresponding to the short side direction, the light emitted from each pixel has a telecentric state in which the emission angle becomes farther away from the center of the display surface of the spatial light modulator 60, that is, in the space. The angle formed by the display surface of the light modulator 60 and the principal ray indicated by the one-dot chain line of the image display light moves away from the vertical state, and the numerical aperture NA is made relatively small.

The illumination conditions according to the emission angles in the X direction and the Y direction shown in FIGS. 13 and 14 may be the illumination conditions shown in Table 1 and Table 2 described above as comparative examples with respect to the first embodiment described above. Good.
In the case of the illumination conditions shown in Table 1 and Table 2, the spread angle is about ± 20 degrees in the X direction, whereas the spread angle is about ± 5 degrees in the Y direction. That is, the numerical aperture NA is large in the X direction, and the numerical aperture NA is small in the Y direction.
That is, in this case, it can be seen that the numerical aperture of the emitted light and the emission angle of the principal ray are different from each other in one direction and the other direction, that is, the X direction and the Y direction.

The reason why the numerical aperture NA and the emission angle have anisotropy with respect to the X direction and the Y direction in the above-described virtual image display device will be described with reference to FIGS. 15A and 15B and FIG. To do.
As described in FIG. 12A, in the traveling direction corresponding to the long side direction (X direction) of the spatial light modulator, the number of times of reflection in the light guide plate 90 is different depending on each angle of view, that is, the optical path length is different. As shown in FIG. 15A, since the propagating light beams are all parallel light beams, the angle of view emitted from the light guide plate is different even if the light beam group advances and the optical path length of the light beams of each angle of view changes so as to be folded. The image is not disturbed because it is unchanged. In this case, the aperture in the X direction in the collimating optical system 70 can be made relatively small.

  On the other hand, in the short side direction (Y direction) of the spatial light modulator, as shown in FIG. 15B, the vertical angle of view is farther away as is apparent when reverse ray tracing is performed from the exit pupil. As described above, when applied to a head-mounted display, if the optical system is disposed laterally with respect to the pupil, the length Lg of the light guide plate needs to be about 60 mm from the average size of a human face, for example. It becomes. If the light is reflected in the Y direction, that is, the vertical direction inside the light guide plate 90, the image is inverted up and down. Therefore, if the light is advanced without being reflected in the Y direction as described above, the light reaches the collimating optical system 70. And the diameter in the Y direction increases. In other words, in this case, the upper and lower (Y-direction) angle-of-view rays are configured to deviate from the telecentric state with respect to the spatial light modulator 60.

On the other hand, numerical apertures NAx and NAy in the X direction and Y direction are as follows, respectively.
First, the numerical aperture NAy in the Y direction is such that the pupil diameter of the observer is D and the focal length of the collimating optical system 70 is f.
NAy = D / (2f)
It becomes.

On the other hand, the numerical aperture NAx in the X direction is not uniquely determined from the pupil diameter as in the Y direction because the light beam is reflected back in the light guide plate as described above.
That is, as is apparent from backtracking in the configuration diagram shown in FIG. 16, there is a light beam that is reflected back and reflected at a position straddling the edge of the first reflective volume hologram grating 93 and the optical surface 92. When reverse ray tracing is performed, a part of this light beam (that is, a part reflected by the optical surface 92) is repeatedly reflected and diffracted at different positions of the first reflective volume hologram grating 93 to reach the collimating optical system 70. . On the other hand, the remaining light flux is diffracted at the end of the first reflective volume hologram grating 93 and reaches the collimating optical system 70 as it is. That is, this light beam is a parallel light beam having the same angle of view emitted from the same pixel, but is diffracted and reflected by different parts of the first reflection type volume hologram grating 93 and combined and propagated in the light guide plate 90. There will be a luminous flux that
In order to allow light to reach the entire area of the pupil 80, it is desirable to illuminate including a so-called branched light beam. However, it is difficult to illuminate the light emitted from one pixel into two divergent lights. . Therefore, as shown in FIG. 16, it is necessary to increase the apparent NAx of the illumination light. In FIG. 16, parts corresponding to those in FIG.
Therefore, it can be seen that in this optical system, the apparent numerical aperture NAx in the X direction is relatively large, and the numerical aperture NAy in the Y direction is relatively small.

As described above, in the virtual image display device according to the above-described embodiment, the spatial light modulation unit changes from the spatial light modulation unit to the collimating optical system due to the configuration conditions such as the shape of the light guide plate and the traveling form of the light beam in the light guide plate. Optical characteristics having anisotropy in which the emission angle and numerical aperture of the principal ray corresponding to each emitted pixel are different in the X direction and the Y direction are required.
On the other hand, in the present embodiment, as described above, the diffusion plate 40 is provided in the illumination optical system for the spatial light modulation unit, and the Fresnel lenses 31 and 32, the diffusion plate 40, and the optical light of the multi-light pipe 20 are provided. Similar to the spatial light modulation optical apparatus in the first to fourth embodiments described above, the characteristics are close to telecentric in the X direction (x direction), for example, and the diffusion angle is relatively large, and the Y direction (y In the direction), illumination optics that appropriately illuminate the spatial light modulator when applied to the above-mentioned virtual image display device by being constructed with optical anisotropy such as deviating from telecentricity and making the diffusion angle relatively small. An apparatus can be provided.

As a result, the emitted light that displays the image modulated by the spatial light modulator propagates through the light guide plate with a desired numerical aperture and emission angle, and reaches the pupil without waste and without causing image distortion. Therefore, according to the illumination optical device and the virtual image display device of the present invention, as described above, the light is efficiently used with uniform luminance, so that the brightness does not change even if the pupil 80 is displaced or rotated. And a good image can be displayed.
Furthermore, in the present invention, a plurality of light pipes and light sources are arranged, and the number of arrays corresponding to the long side direction of the spatial light modulator is larger than the number of arrays corresponding to the short side direction. Therefore, even when a reflective spatial light modulation unit is used, a virtual image display device that performs more uniform illumination on the spatial light modulation unit, is excellent in efficiency, and can suppress luminance unevenness and perform good display Can be provided.

[6] Sixth Embodiment Next, with reference to FIGS. 17A and 17B, an embodiment of a projection type image display apparatus using the spatial light modulation optical apparatus according to the present invention will be described. FIG. 17A shows a schematic plan configuration diagram and a schematic side configuration diagram seen from the top surface of the projection type image display apparatus 300. In this example, the spatial light modulation optical device having the configuration described in the third embodiment is used. The light source 10 such as an LED, the multi-light pipe 20, the diffuser plate 40, the polarization beam splitter 50, the reflection A spatial light modulator 60 of the mold, a projection optical system 310, and a screen 311 are included. In FIGS. 17A and 17B, parts corresponding to those in FIGS.

  In such a configuration, the illumination light emitted from the light source 10 is incident from the light incident surface 21 having the smaller area of each light pipe of the multi-light pipe 20 optically in close contact with the light source 10, and a part of the light rays is inside. After repeating the total reflection, the light is emitted from the light exit surface 22 of each light pipe, and after being appropriately diffused by the diffuser plate 40 disposed subsequently, enters the polarization beam splitter 50 from the optical surface 51. Subsequently, the S polarization component of the illumination light is reflected by the polarization separation film 52 and the P polarization component is transmitted. The reflected S-polarized light component is emitted from the optical surface 53 of the polarization beam splitter 50 and illuminates the reflective spatial light modulator 60.

  The illumination light mainly having an S-polarized light component incident on the reflective spatial light modulator 60 is modulated in the polarization state for each pixel of the reflective spatial light modulator 60, and the ratio of the P-polarized component and the S-polarized component is Controlled and reflected. The illumination light reflected by the reflective spatial light modulator 60 is incident again on the polarization beam splitter 50, and the P-polarized component is transmitted through the polarization separation film 52, and is emitted from the optical surface 54.

The illumination light emitted from the polarization beam splitter 50 is projected on the screen 311 by the projection optical system 310, and an image of display light (video light) modulated by the spatial light modulation unit 60 by image information or the like is formed.
Also in this example, in the spatial light modulation optical device, luminance unevenness can be suppressed without increasing the size of the light pipe. In this example, by arranging the plurality of light pipes to be inclined toward the center direction of the spatial light modulator, the number of optical lenses used can be reduced or eliminated, and further reduction in size and weight can be achieved.
Therefore, the projection-type image display device 300 using such a spatial light modulation optical device is excellent in illumination efficiency, and can display a good image by suppressing unevenness in luminance, and can be reduced in size and weight. It becomes possible.

As described above, according to the present invention, the non-uniformity of brightness is suppressed as compared with the conventional case, and a small spatial light modulation optical device excellent in light utilization efficiency, and a virtual image display device and a projection type image display using the same. An apparatus can be provided.
The spatial light modulation optical device, the virtual image display device, and the projection type image display device according to the present invention are not limited to the embodiments described above, and other types such as a light source, a spatial light modulation unit, and a light pipe. Needless to say, various modifications and changes can be made without departing from the configuration of the present invention, such as the layout and arrangement.

1A is a schematic plan configuration diagram of an embodiment of a spatial light modulation optical device according to the present invention. FIG. B is a schematic side view of an embodiment of a spatial light modulation optical device according to the present invention. FIG. 3A is a diagram showing a ray trace of an embodiment of a spatial light modulation optical device according to the present invention. B is a diagram showing a ray trace of an embodiment of the spatial light modulation optical device according to the present invention. It is a figure which shows the illumination intensity distribution in one embodiment of the spatial light modulation optical apparatus by this invention. A is a schematic plan view of a comparative example of a spatial light modulation optical device. B is a schematic side view of a comparative example of a spatial light modulation optical device. A is a figure which shows the light ray trace of the comparative example of a spatial light modulation optical apparatus. B is a diagram showing a ray trace of a comparative example of the spatial light modulation optical device. It is a figure which shows the illumination intensity distribution in the comparative example of a spatial light modulation optical apparatus. 1A is a schematic plan configuration diagram of an embodiment of a spatial light modulation optical device according to the present invention. FIG. B is a schematic side view of an embodiment of a spatial light modulation optical device according to the present invention. FIG. 3A is a diagram showing a ray trace of an embodiment of a spatial light modulation optical device according to the present invention. B is a diagram showing a ray trace of an embodiment of the spatial light modulation optical device according to the present invention. It is a figure which shows the illumination intensity distribution in one embodiment of the spatial light modulation optical apparatus by this invention. 1A is a schematic plan configuration diagram of an embodiment of a spatial light modulation optical device according to the present invention. FIG. B is a schematic side view of an embodiment of a spatial light modulation optical device according to the present invention. 1A is a schematic plan configuration diagram of an embodiment of a spatial light modulation optical device according to the present invention. FIG. B is a schematic side view of an embodiment of a spatial light modulation optical device according to the present invention. 1A is a schematic plan configuration diagram of an embodiment of a virtual image display device according to the present invention. FIG. B is a schematic side view of an embodiment of a virtual image display device according to the present invention. It is explanatory drawing of the emission angle and numerical aperture of the x direction of the light inject | emitted from the spatial light modulation part. It is explanatory drawing of the emission angle and numerical aperture of the y direction of the light inject | emitted from the spatial light modulation part. A is an explanatory diagram in which reverse ray tracing in the x direction is performed from the exit pupil. B is an explanatory diagram in which reverse ray tracing in the y direction is performed from the exit pupil. It is explanatory drawing of the numerical aperture of the x direction of one Example of the virtual image display apparatus by this invention. 1A is a schematic plan configuration diagram of an embodiment of a projection type image display apparatus according to the present invention. FIG. B is a schematic side view of an embodiment of a projection type image display device according to the present invention. It is a schematic block diagram of an example of the conventional illumination optical apparatus. It is a schematic block diagram of an example of the image projection apparatus using the conventional light pipe. A is a schematic block diagram of an example of a virtual image display device using a light pipe. B is a schematic configuration diagram of an example of a virtual image display device using a light pipe. C is a schematic configuration diagram of an example of a virtual image display device using a light pipe. It is a schematic block diagram of an example of the spatial light modulation optical apparatus using a light pipe.

Explanation of symbols

  10. Light source 20, light pipe, 21. Incident surface, 22. Emission surface, 23. Side, 30. Fresnel lens, 49. Diffusion plate, 50. Polarization beam splitter, 51. Optical surface, 52. Polarization separation surface, 53. Optical surface, 54. Optical surface, 60. Spatial light modulator 70. Collimating optical system, 80. Pupil, 90. Light guide plate, 91. Optical surface, 91A. Incident part, 91B. Injection part, 92. Optical surface, 93. First reflective volume hologram grating, 94. Second reflective volume hologram grating, 100. Spatial light modulation optical device, 200. Virtual image display device, 210. Virtual image display optical system, 300. Projection-type image display device 310. Projection optical system, 311. screen

Claims (3)

A virtual image display device comprising: a spatial light modulation optical device; and a virtual image imaging optical system for guiding a display image of the spatial light modulation optical device to an observer's pupil,
The spatial light modulation optical device includes a plurality of light sources, a plurality of light pipes, a spatial light modulation unit, and a diffusion plate.
The light sources are respectively disposed in the vicinity of incident surfaces of the plurality of light pipes,
In the spatial light modulator, the width of the illumination area is different in one direction and the other direction,
The number of the light pipes corresponding to the direction in which the width of the illumination area is large is larger than the number of the light pipes corresponding to the direction in which the width of the illumination area is small;
The light beam emitted from the light source is incident on the light pipe from the incident surface, and after at least a part of the light beam is totally internally reflected on the side surface, the light beam is emitted from the emission surface having a larger area than the incident surface. Then, the light guided to the spatial light modulation unit, the light modulated in the spatial light modulation unit is incident on the virtual image imaging optical system,
The virtual image imaging optical system includes a collimating optical system that converts light beams emitted from the pixels of the spatial light modulation unit into parallel light beam groups having different traveling directions, and the parallel light beam groups that are incident on the collimated light beam groups. The light guide plate is configured to be reflected and propagated multiple times in the left-right direction with respect to the observer's pupil without being reflected in the vertical direction with respect to the observer's pupil, and then emitted toward the observer's pupil. And
The light guide plate includes a first reflective volume hologram grating that diffracts and reflects the parallel light beam group so as to satisfy an internal total reflection condition in the light guide plate while maintaining the parallel light beam group in the incident region of the parallel light beam group; A second reflective volume hologram grating that diffracts and reflects the parallel light beam group so as to be emitted from the light guide plate as a parallel light beam group in an emission region of the parallel light beam group;
The diffusion plate is provided between the plurality of light pipes and the spatial light modulator, and has a diffusivity in which a horizontal diffusion angle with respect to the observer's pupil is larger than a vertical diffusion angle with respect to the observer's pupil. Yes, and the vertical direction of the diffusion angle, the virtual image display device in which the parallel light flux group entering the virtual image forming optical system is set to a size that does not spread in the vertical direction. Mutually parallel light pencil groups traveling in different directions, the virtual image display device according to claim 1, wherein the total number of reflections are different to each reaching the second reflection volume hologram grating. In the virtual image imaging optical system, the numerical aperture and / or the chief ray emission angle of the light emitted from the spatial light modulation unit are different from each other in one direction and the other direction in the plane of the spatial light modulation unit. The virtual image display device according to claim 1 .