JP2007033669A - Spatial light modulation optical device, and virtual image display device and projection-type image display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a virtual image display device and a projection-type image display device which have simple constitution as a whole, and also have high light use efficiency by obtaining high light use efficiency with relatively simple constitution in a spatial light modulation optical device which uses a reflection-type spatial light modulation part. <P>SOLUTION: The spatial light modulating optical device comprises a light source 10, a prism 20 on which illumination emitted by the light source 10 is made incident, and the reflection type spatial optical modulation part 50 irradiated with illumination light emitted from the prism 40, and the prism 40 has a plurality of reflecting surfaces 41 and 42, reflecting the incident illumination light and a polarized light separation part 43 which separates the illumination light reflected by these reflecting surfaces according to a polarized light component, and the illumination light reflected by the reflection-type spatial optical modulation part 50 is made incident on the prism 40 again and separated by the polarization separation part 43 according to its polarization state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a spatial light modulation optical device including a reflective spatial light modulation unit and its illumination optical system, and in particular, a virtual image display device such as a viewfinder of a video camera, a head-mounted display, a front projection, a rear projection, etc. The present invention relates to a spatial light modulation optical device suitable for being applied to the projection type image display device, a virtual image display device and a projection type image display device using the same.

Currently, as a spatial light modulator usable in various display devices, there is a technology that uses a reflective spatial light modulator such as a reflective liquid crystal panel in parallel with a transmissive spatial light modulator such as a transmissive liquid crystal panel. It is being considered.
The reflective liquid crystal panel has an advantage that the light use efficiency is superior to the transmissive liquid crystal panel. On the other hand, the quality of the image quality depends on the illumination optical system that guides the light from the light source to the reflective liquid crystal panel and guides the light modulated by the reflective liquid crystal panel to the projection lens and the pupil. A device is required for the configuration of the optical system.
As a spatial light modulation optical apparatus using a reflective spatial light modulation unit, for example, a method using a cube-type polarization beam splitter has been proposed (see, for example, Patent Document 1).
In the optical system described in Patent Document 1, as shown in a schematic configuration diagram in FIG. 16, the optical system is placed close to the optical surfaces 125 </ b> A and 125 </ b> B of a cube-type polarization beam splitter (PBS) 125, respectively. The planar illumination light source device 121 and a reflective spatial light modulation unit 122 are arranged in which a light source close to a point light source or a light source close to a point light source is enlarged in a planar shape.

  As shown in FIG. 16, in this example, a polarizer 123 and a planar illumination light source device 121 are arranged in this order so as to face the first surface 125A of the PBS 125, and are reflected so as to face the second surface 125B. A quarter-wave plate 126 and a reflection mirror 127 are arranged in this order so that the mold spatial light modulator 122 faces the third surface 125C.

  In such a configuration, the light emitted from the planar illumination light source device 121 passes through the polarizer 123, is deflected by the polarization separation surface 125 </ b> E of the PBS 125, and reaches the reflective spatial light modulator 122. The reflected spatial light modulator 122 outputs modulated reflected light. This reflected light passes through the polarization separation surface 125E and the quarter-wave plate 126, and reflects the concave reflection surface of the reflection mirror 127. The reflected light passes through the quarter-wave plate 126 again, is deflected by the polarization separation surface 125E, and is emitted from the fourth surface 125D of the PBS 125 as indicated by the arrow Lo, so that the human pupil in the observation region 130 It is possible to observe the image information or the like that reaches 131 and is modulated by the reflective spatial light modulator 122.

US Pat. No. 5,596,451

As in the above-mentioned Patent Document 1, when PBS is simply used, there is a problem that it is difficult to construct a spatial light modulation optical device with high light utilization efficiency.
To explain this, in the spatial light modulation optical device shown in FIG. 16, it is difficult to control the numerical aperture of the illumination light emitted from each point of the planar illumination light source device 121, so that the light use efficiency decreases. End up. For example, assuming that the pupil diameter D of the virtual image optical system is 6 mm and the focal length f of the reflecting mirror 127 that is a concave mirror is 20 mm, in this case, of the light beams emitted from the reflective spatial light modulator 122, the pupil 131 effectively reaches the pupil 131. The numerical aperture NA of the luminous flux is
NA · f = D / 2
Than,
NA = 0.15
And the radiation solid angle θ is 8.6 degrees.

Usually, in the case of a surface emitting light source using a light guide plate, the solid angle at which the peak light intensity is halved is as large as about 30 degrees. Therefore, the illumination light having a radiation solid angle of 8.6 degrees or more does not reach the pupil 131, and the light utilization efficiency is very poor.
When such a spatial light modulation optical device is used in various display devices, in particular, a projection type image display device, it is an important issue to increase the light use efficiency, and the deterioration of the light use efficiency is a big problem. Become.

  On the other hand, it is conceivable to construct a spatial light modulation optical device using a light pipe. However, especially when the spatial light modulation unit is a reflection type, an optical component such as a polarization beam splitter is used as a light source and this spatial light modulation. Since the distance between the exit surface of the illumination optical system and the spatial light modulator is relatively large, the length of the light pipe is increased in order to increase the illumination numerical aperture. There is a problem that it ends up.

This will be described with reference to FIG. FIG. 17 shows a case where the light pipe 20, the PBS 60, and the reflective spatial light modulator 50 are arranged on the optical path of the light emitted from the light source 10. Then, the illumination condition is telecentric, that is, the state where the central ray is perpendicularly incident on the spatial light modulator, and the illumination half-value angle is θd. Further, the width of the reflective spatial light modulator 50 where the illumination light is incident is Wd, and the distance from the light pipe 20 is Ls. Thus, the width W1h of the exit surface 23 of the light pipe 2 is
W1h = Wd + 2Ls × tan (θd)
It becomes.

  As described above, in the case of a reflective spatial light modulation unit in which PBS is interposed, the distance Ls from the exit surface 22 of the light pipe 20 must be longer than that of the transmission spatial light modulation unit. When the number NA is large, the illumination half-value angle θd is also increased, and as a result, the width W1h of the exit surface 23 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 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 23 while undergoing total internal reflection at the side surface 22 of the light pipe 20. In the light pipe, the uniformity of the luminance of the illumination light emitted from the exit surface 23 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 illumination light incident on the periphery of the reflective spatial light modulator 50 is tilted, the length of the light pipe 20 depends on the tilt direction. Lh is affected.
As described above, it is found that if the light use efficiency is increased in the optical device using the reflection type spatial light modulator by using only the light pipe, it is disadvantageous for downsizing.
In the above spatial light modulation optical device, in order to control the numerical aperture and chief ray angle of light incident on the reflective spatial light modulation unit, for example, a diffusion plate or a Fresnel lens may be provided. Has a problem that it is difficult to maintain high light utilization efficiency.

  In view of the problems described above, it is an object of the present invention to suppress a decrease in illumination use efficiency with a relatively simple device configuration in a spatial light modulation optical device using a reflective spatial light modulation unit. Accordingly, it is an object of the present invention to provide a virtual image display device and a projection display device using a spatial light modulation optical device having a high light utilization efficiency and a relatively simple configuration.

  In order to solve the above-described problems, the present invention provides a spatial light modulation optical device that includes a light source, a prism on which illumination light emitted from the light source is incident, and a reflective spatial light modulation unit that is illuminated by illumination light emitted from the prism. The prism has a plurality of reflection surfaces that reflect incident illumination light, and a polarization separation unit that separates the illumination light reflected by the plurality of reflection surfaces according to the polarization component, and is a reflection type The illumination light reflected by the spatial light modulator is incident on the prism again from the same plane as the exit surface, and is separated by the polarization separator according to the polarization state.

Further, the virtual image display device and the projection type image display device according to the present invention are configured to use the spatial light modulation optical device described above.
That is, the present invention relates to 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 an observer's pupil. A spatial light modulation optical device having a prism on which illumination light emitted from a light source is incident and a reflective spatial light modulator that is illuminated by illumination light emitted from the prism, wherein the prism reflects incident illumination light A plurality of reflecting surfaces and a polarization separating unit that separates the illumination light reflected by the plurality of reflecting surfaces according to the polarization component, and the illumination light reflected by the reflective spatial light modulation unit is applied to the prism. The light is incident again from the same surface as the exit surface, separated by the polarization separation unit, and then incident on the virtual image optical system.

  Furthermore, the present invention provides a projection-type image display device that includes a spatial light modulation optical device and a projection optical system that projects a display image of the spatial light modulation optical device. The spatial light modulation optical device includes a light source and a light source. The prism includes a prism on which the emitted illumination light is incident, and a reflective spatial light modulator that is illuminated by the illumination light emitted from the prism. The prism includes a plurality of reflection surfaces that reflect the incident illumination light, and the plurality of reflections. The illumination light reflected by the surface is separated according to its polarization component, and the illumination light reflected by the reflective spatial light modulator re-enters the prism from the same plane as the exit surface. Then, after being separated by the polarization separation unit, the light enters the projection optical system.

As described above, the spatial light modulation optical device according to the present invention is a reflection-type spatial light modulation unit that emits illumination light emitted from a light source having a relatively small light-emitting unit such as an LED or a laser by a prism having a plurality of reflection surfaces. The chief ray incident angle and the numerical aperture at each point are controlled, and the reflection-type spatial light modulation unit is illuminated after detection in a single polarization state by the polarization separation unit existing inside the prism.
Therefore, by arranging the prism that can control the chief ray incident angle and the numerical aperture as described above and has a polarization separation function, the reflective spatial light modulator can be used to achieve high light utilization efficiency and relatively A spatial light modulation optical device with a simple device configuration can be provided.

As described above, according to the present invention, in a spatial light modulation optical device using a reflective spatial light modulation unit, it is possible to suppress a decrease in light utilization efficiency with a relatively simple device configuration.
Further, according to the virtual image display device and the projection type image display device according to the present invention, the light utilization efficiency is high, and the device configuration can be simplified.

  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.

[1] First Embodiment With reference to FIG. 1, a first embodiment of the spatial light modulation optical device according to the present invention will be described. The spatial light modulation optical device 100 of this example includes a light source 10 composed of an LED, a semiconductor laser, etc., a light pipe 20, a reflective polarizing plate 30, a plurality of reflecting surfaces, in this example, two reflecting surfaces 41 and 42 and polarized light. An example in which the prism 40 having the separation unit 43 and the reflection type spatial light modulation unit 50 including a reflection type liquid crystal panel or the like is used will be described.

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 light pipe 20, and after a part of the light rays repeats total internal reflection, the light is emitted from the emission surface 22. .
Thus, when providing the light pipe 20, it can function as a numerical aperture reduction part. Further, when the light source 10 is composed of a plurality of LEDs, particularly LEDs of various colors such as red, green, and blue, it is possible to efficiently mix light. Further, when a light source such as a plurality of single color LEDs is used, these lights can be mixed efficiently and the uniformity of the illumination light can be maintained.

Illumination light emitted from the emission surface 22 is reflected by the reflective polarizing plate 30 disposed subsequently, for example, an S-polarized component (polarized component perpendicular to the paper surface of FIG. 1), and a P-polarized component (paper surface of FIG. 1). (Polarization component parallel to) transmits. The reflected illumination light of the S-polarized component is incident on the light pipe 20 again and part of it returns to the light source 10. Since a reflection plate (not shown) is provided on the light emitting surface of the light source 10 other than the light emitting part, the returned illumination light is reflected again and enters the reflective polarizing plate 30. In this process, the returned polarized light undergoes total internal reflection within the light pipe 20, so that its polarization state changes and a P-polarized light component is generated. Therefore, the P-polarized light component is transmitted through the reflective polarizing plate 30 at the second incidence. The remaining S-polarized light repeats this routine again.
Therefore, when the reflective polarizing plate 30 instead of the absorption type is provided on the incident surface side of the prism 40 as described above, there is an advantage that the light use efficiency can be further improved.

The P-polarized light component transmitted through the reflective polarizing plate 30 enters the prism 40 and is reflected by the first reflecting surface 41, and then the first reflecting surface reaches a region where the reflected light from the first reflecting surface 41 reaches. The light is reflected by a second reflecting surface 42 provided to face 41.
In the present embodiment, the two reflecting surfaces 41 and 42 are in one direction on the display surface of the reflective spatial light modulator 50 and in a different direction, that is, for example, arrows corresponding to the long side direction and the short side direction. In the long side direction (x direction) indicated by x and the short side direction (y direction) indicated by arrow y, the toric surfaces have different curvatures.

The illumination light reflected by the two reflecting surfaces 41 and 42 is subsequently reflected by the polarization separation unit 43 existing inside the prism 40 and is transmitted by the P-polarized light. The transmitted P-polarized light is emitted from the exit surface 44 of the prism 40 and illuminates the reflective spatial light modulator 50.
In addition, as the polarization separation part 43, the polarization separation film of the structure which extended | stretched the polymer film of a multilayered structure, a wire grid type polarization separation element, etc. can be used, for example.

  The illumination light reflected by the reflective spatial light modulation unit 50 enters the prism 40 again from the optical surface 44 and enters the polarization separation unit 43. Here, only the S-polarized light component of the illumination light whose polarization state is modulated for each pixel by the reflective spatial light modulation unit 50 is reflected by the polarization separation unit 43, and is indicated by an arrow Lm from the other exit surface 45 of the prism 40. As shown, it is emitted as modulated image display light, for example.

In the present embodiment, the light source 10 and the light pipe 20 are in optical contact with each other, so that the light use efficiency can be kept high.
Also, in this example, illumination light emitted from a light source having a relatively small light-emitting portion such as an LED or a laser can be passed through the light pipe 20 to reduce numerical aperture and mix RGB colors.
In this case, in the prism 40 having the reflection surfaces 41 and 42 made of the above-described toric surface in the prism 40, the chief ray incident angle and numerical aperture corresponding to each pixel of the reflective spatial light modulator 50 are controlled, The reflected spatial light modulation unit 50 can be illuminated after detection in a single polarization state by the polarization separation unit 43 existing inside the prism 40.

  In this example, the light incident on the prism 40 is aligned with the P-polarized light, but only a part of the P-polarized light is reflected by the polarization separation unit 43. Further, when birefringence occurs due to the material of the prism 40, part of the light becomes S-polarized light while propagating through the prism 40, and part of the light is reflected by the polarization separation unit 43. This light may cause a so-called ghost when applied to a virtual image display device or a projection image display device. However, in this embodiment, the light is emitted from the prism 40 in a direction different from the direction in which the image display light Lm is emitted, as indicated by the broken line arrow Lg, in the polarization separation unit 43 of the prism 40. This is advantageous in that unnecessary light that causes ghosts is separated and image quality is not impaired.

When the illumination conditions of the reflective spatial light modulator 50 are different between the short side direction and the long side direction, the reflecting surfaces 41 and 42 of the prism 40 are thus toric surfaces, or By using a non-axisymmetric reflecting surface having no symmetry axis in the plane, it is possible to efficiently illuminate according to the illumination condition.
Further, in this example, the polarization separation unit 43 of the prism 40 is used to transmit the illumination light between the reflection surfaces 41 and 42 in the two reflection surfaces 43 just before entering the polarization separation unit 43. The example arrange | positioned in the inclination direction along a advancing direction is shown. That is, the path of the illumination light is obstructed by setting the inclination direction of the polarization separation unit 43 in this way to the direction along the traveling direction of the illumination light from the first reflection surface 41 toward the second reflection surface 42. This has the advantage that the prism 43 can be configured without any problem.
As described above, in this embodiment, the reflection type has a relatively simple device configuration in which only a light pipe and a prism are provided, high light utilization efficiency, illumination conditions of a desired numerical aperture and chief ray angle. A spatial light modulation optical device capable of illuminating the spatial light modulation unit can be provided.

[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 FIGS. 2A and 2B. 2A is a schematic top view of the spatial light modulation optical device 100 according to the present embodiment, and FIG. 2B is a schematic side view of the configuration. Also in this case, the spatial light modulation optical device 100 includes a light source 10 such as an LED, a light pipe 20, a diffusing unit 35, reflecting surfaces 41 and 42 including two toric surfaces, a prism 40 having a polarization separating unit 43, and a reflective type. The spatial light modulator 50 is configured. 2A and 2B, parts corresponding to those in FIG.

That is, in this example, an example in which the diffusing portion 35 is provided in place of the reflective polarizing plate in the first embodiment shown in FIG. In the first embodiment, the illumination is telecentric with respect to the reflective spatial light modulator 50. In this embodiment, as shown in FIG. Although it is telecentric for the long side direction (x direction), as shown in FIG. 2B, for the short side direction (y direction) indicated by the arrow y, the illumination light is reflected spatially modulated in the y direction. Inclined toward the center of the portion 50. That is, in this case as well, an example in which the reflecting surfaces 41 and 42 of the prism 40 are toric surfaces is shown, and the asymmetry is performed in different directions on the display surface of the spatial light modulator 50 by adopting a configuration through these toric surfaces. Trick lighting conditions can be easily realized.
Further, in this example, the diffusing unit 35 is provided with the diffusing unit 35 between the light source 10 and the reflecting surface of the prism 40, and in the illustrated example, between the light pipe 20 and the first reflecting surface 41. By controlling the chief ray angle and the numerical aperture, the uniformity of the illumination light within the plane and within the radiation angle can be further improved as compared with the case of the first embodiment described above.
Also in this embodiment example, similarly to the above-described first embodiment example, with a high light utilization efficiency and with a relatively simple configuration in which only the prism 40 is arranged without enlarging the apparatus, It is possible to provide a spatial light modulation optical device that can illuminate the reflective spatial light modulation unit 50 with favorable illumination conditions.

[3] Third Embodiment Next, a third embodiment of the spatial light modulation optical device according to the present invention will be described with reference to FIG. Also in this example, the spatial light modulation optical device 100 includes a light source 10 such as an LED, a light pipe 20, a prism 40 having two reflection surfaces 41 and 42, and a polarization separation unit 43, and a reflection type spatial light modulation unit 50. ing. This example shows an example in which the exit surface 22 and the side surface 23 of the light pipe 20 are curved outwardly convex, and an example in which a diffusion unit 35 is provided on the incident side of the polarization separation unit 43 is shown. In FIG. 3, parts corresponding to those in FIG.

  In this example, the illumination light emitted from the light source 10 such as an LED is incident from the incident surface 21 having a relatively small area of the light pipe 20, and after a part of the light rays have undergone total internal reflection, from the emission surface 22. Eject. Like the light pipe 20 in this embodiment, the side surface 23 and the emission surface 22 are configured by curved surfaces, whereby the spread angle of the illumination light emitted from the emission surface 22 of the light pipe 20 can be reduced.

Also in this case, an example in which the reflecting surfaces 41 and 42 of the prism 40 are toric surfaces is shown, and the asymmetry is performed in different directions on the display surface of the spatial light modulator 50 by adopting a configuration through these toric surfaces. Trick lighting conditions can be easily realized.
Further, in this case, since the diffusing unit 35 is provided on the incident side of the polarization separating unit 43, the diffusing unit 35 can also control the numerical aperture and chief ray angle of the illumination light. Particularly in this case, since the diffusing unit 35 is provided on the incident side of the polarization separation unit 43, the display light modulated by the reflective spatial light modulation unit 50 does not pass through the polarization separation unit 50 after entering the prism 40 again. Here, the light is reflected and emitted from the emitting portion 45 to the outside. For this reason, the function of controlling the numerical aperture and chief ray angle of the illumination light as described above is given to the diffusing unit 35 without the display light after modulation being affected by the diffusion, and without impairing the image quality. This has the advantage that the design freedom of the reflecting surfaces 41 and 42 can be increased.
Also in this embodiment example, similarly to the first and second embodiment examples described above, the desired illumination conditions can be satisfactorily achieved with high light utilization efficiency and with a relatively simple configuration in which only the prism 40 is disposed. Thus, it is possible to provide a spatial light modulation optical device that illuminates the reflective spatial light modulation unit 50.

[4] Fourth Embodiment Next, a fourth embodiment of the reflective spatial light modulation optical device according to the present invention will be described with reference to FIG. The spatial light modulation optical device 100 includes a light source 10 such as an LED, a light pipe region 420 and reflection surfaces 41 and 42, a prism 40 having a polarization separation unit 43, and a reflection type spatial light modulation unit 50. That is, in this example, an example in which a light pipe region 420 having a function of reducing the numerical aperture of a light beam and color mixing or mixing is provided in the prism 40 without providing a light pipe separate from the prism 40 is shown.

In such a configuration, the illumination light emitted from the light source 10 is incident from the front end 421 of the light pipe region 420 provided integrally with the prism 40, and after a part of the light rays undergoes total internal reflection, 1 is incident on the reflection surface 41. The reflected illumination light is subsequently reflected by the second reflecting surface 42 facing the first reflecting surface 41.
In the present embodiment, the two reflecting surfaces 41 and 42 are so-called free curved reflecting surfaces that do not have an axis of symmetry within the surfaces. A free-form curved reflecting surface has a higher degree of freedom in surface shape than a toric surface, and enables a wider control of fine illumination light.

The illumination light reflected by these two reflecting surfaces 41 and 42 is then reflected by the S-polarized light and transmitted by the P-polarized light, for example, by the wire grid type polarization separation unit 43 existing inside the prism 40. . The transmitted P-polarized light is emitted from the exit surface 44 of the prism 40 and illuminates the reflective spatial light modulator 50. In the illustrated example, the reflective spatial light modulator 50 is telecentric with respect to the x direction, which is the long side direction, but with respect to the y direction, which is the short side direction, that is, with respect to the vertical direction in FIG. An example in which the light is slightly inclined outward from the center of the reflective spatial light modulator 50 is shown. In this example, as described above, the reflecting surfaces 41 and 42 of the prism 40 are free-form surface reflecting surfaces, and therefore asymmetrical with respect to a plurality of directions in the display surface of the reflective spatial light modulator 50. Lighting conditions can be easily realized.
Also in this embodiment example, similarly to the above-described first embodiment example, with a high light utilization efficiency and with a relatively simple configuration in which only the prism 40 is arranged without enlarging the apparatus, A spatial light modulation optical device that illuminates the reflective spatial light modulation unit 50 satisfactorily can be provided.

[5] Fifth Embodiment Next, a fifth embodiment of the spatial light modulation optical device according to the present invention will be described with reference to FIG. The spatial light modulation optical device 100 includes a light source 10 such as an LED, a light pipe region 420, reflection surfaces 41 and 42, a prism 40 having a polarization separation unit 43, and a reflection type spatial light modulation unit 50. In this example, the image display light modulated by the reflective spatial light modulation unit 50 is transmitted through the polarization separation unit 43 in the prism 40 and is emitted from the exit surface 45 of the prism 40 again.

  In this case, the illumination light emitted from the light source 10 is incident from the tip portion 421 of the light pipe region 420 provided integrally with the prism 40, and after a part of the light rays undergoes total internal reflection, the first reflection is performed. Incident on the surface 41. The reflected illumination light is subsequently reflected by the second reflecting surface 42 facing the first reflecting surface 41. In the present embodiment example, the two reflecting surfaces 41 and 42 are free curved reflecting surfaces having no symmetry axis in the surface, and the degree of freedom of the surface shape is higher than that of the toric surface. Fine control of illumination light becomes possible.

  In this example, the illumination light reflected by the two reflecting surfaces 41 and 42 is then reflected by the polarization separation unit 43 existing inside the prism 40, and the S-polarized light is transmitted, while the P-polarized light is transmitted. It is injected outside. The S-polarized light reflected by the polarization separation unit 43 exits from the exit surface 44 of the prism 40 and illuminates the reflective spatial light modulation unit 50. In the present embodiment, the light is telecentric with respect to the x direction, which is the long side direction of the reflective spatial light modulator 50, but is illuminating light with respect to the y direction, which is the short side direction of the reflective spatial light modulator 50. Is inclined outward from the center of the reflective spatial light modulator 50. That is, also in this example, such asymmetric illumination conditions can be easily realized by passing through the plurality of reflecting surfaces 41 and 42 which are free-form surfaces.

Then, the illumination light reflected by the reflective spatial light modulation unit 50 enters the prism 40 again from the optical surface 44 and enters the polarization separation unit 43. Here, only the P-polarized light component of the illumination light whose polarization state is modulated for each pixel by the reflective spatial light modulator 50 is transmitted and emitted from the exit surface 45 of the prism 40.
Depending on the type of the polarization separation unit 43, scattering may occur at the time of reflection, but when the light modulated by the reflective spatial light modulation unit 50 is transmitted through the polarization separation unit 43 as described above, This has the advantage that image display light can be emitted with good image quality by avoiding the influence of this scattering.
Also in this embodiment, as in the first embodiment described above, the reflective type has a high light utilization efficiency and has a relatively simple configuration in which only the prism 40 is disposed, and has a desired illumination condition. A spatial light modulation optical device that illuminates the spatial light modulation unit 50 can be provided.

[6] Sixth Embodiment Next, a sixth embodiment of the spatial light modulation optical device according to the present invention will be described with reference to FIGS. 6A and 6B. The spatial light modulation optical device 100 includes a light source 10 such as an LED, a light pipe region 420, reflection surfaces 41 and 42, a prism 40 having a polarization separation unit 43, and a reflection type spatial light modulation unit 50.
Also in this example, as in the fifth embodiment, the image display light modulated by the reflective spatial light modulation unit 50 passes through the polarization separation unit 43 in the prism 40 and is emitted from the prism 40 again. The example inject | emitted from the surface 45 is shown. In this example, the polarization separation unit 43 is arranged to separate the illumination light in a direction orthogonal to a plane substantially along the traveling direction of the illumination light traveling in the prism 40, that is, in a direction orthogonal to the paper surface of FIG. An example in which the light modulated by the reflective spatial light modulator 50 is transmitted through the polarization separation unit 43 and emitted from the prism 40 is shown.

  In this case, the illumination light emitted from the light source 10 is incident from the tip portion 421 of the light pipe region 420 provided integrally with the prism 40, and after a part of the light rays undergoes total internal reflection, the first reflection is performed. Incident on the surface 41. The reflected illumination light is subsequently reflected by the second reflecting surface 42 facing the first reflecting surface 41. In the present embodiment example, the two reflecting surfaces 41 and 42 are free curved reflecting surfaces having no symmetry axis in the surface, and the degree of freedom of the surface shape is higher than that of the toric surface. Fine control of illumination light becomes possible.

  In this example, the illumination light reflected by the two reflecting surfaces 41 and 42 is reflected by the polarization separating unit 43 existing inside the prism 40, the S-polarized light is transmitted, and the P-polarized light is transmitted. It is injected. The S-polarized light reflected by the polarization separation unit 43 exits from the exit surface 44 of the prism 40 and illuminates the reflective spatial light modulation unit 50. In the present embodiment, the light is telecentric with respect to the x direction, which is the long side direction of the reflective spatial light modulator 50, but is illuminating light with respect to the y direction, which is the short side direction of the reflective spatial light modulator 50. Is inclined outward from the center of the reflective spatial light modulator 50. That is, also in this example, such asymmetric illumination conditions can be easily realized by passing through the plurality of reflecting surfaces 41 and 42 which are free-form surfaces.

The illumination light reflected by the reflective spatial light modulation unit 50 enters the prism 40 again from the optical surface 44 and enters the polarization separation unit 43. Here, only the P-polarized light component of the illumination light whose polarization state is modulated for each pixel by the reflective spatial light modulator 50 is transmitted and emitted from the exit surface 45 of the prism 40.
By adopting such a configuration, this embodiment also has an advantage that image display light can be emitted with good image quality while avoiding the influence of scattering at the time of reflection of the polarization separation unit 43.
Also in this embodiment example, as in the first to fifth embodiment examples described above, it is relatively simple to simply arrange the prism 40 with high light utilization efficiency and without enlarging the apparatus. With the configuration, it is possible to provide a spatial light modulation optical device that illuminates the reflective spatial light modulation unit 50 satisfactorily.

[7] Seventh 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. 7 is a schematic side configuration diagram of the virtual image display device 200, FIG. 8A is a schematic top configuration diagram, and FIG. 8B is a schematic side configuration diagram viewed from the pupil side of the observer. 7 and 8A and B show a common xyz coordinate system, with respect to the observer's pupil 80, the horizontal (horizontal) direction is the x direction, the vertical (vertical) direction is the y direction, and the depth direction is the z direction. .
As shown in FIG. 7, the virtual image display device 200 includes a light source 10 such as an LED, a light pipe region 420, a prism 40 having reflective surfaces 41 and 42, and a polarization separation unit 43, a reflective spatial light modulation unit 50, and a finder lens. A collimator optical system 70 such as a light guide plate 90 made of a hologram waveguide or the like.

  As shown in FIG. 7, in this case, the illumination light emitted from the light source 10 is incident from the tip portion 421 having the smaller area of the light pipe region 420 of the prism 40 that is optically in close contact with the light source 10, and is partially Of the light beam repeats total internal reflection, and then enters the first reflecting surface 41. The illumination light reflected by the first reflecting surface 41 is subsequently reflected by the second reflecting surface 42 facing the first reflecting surface 41. In the present embodiment, the two reflecting surfaces 41 and 42 are so-called free-form reflecting surfaces that do not have an axis of symmetry within the surfaces. As described above, the free curved surface reflecting surface has a higher degree of freedom in the surface shape than the toric surface and enables fine control of illumination light.

  The illumination light reflected by the two reflecting surfaces 41 and 42 is then reflected by the polarization separation unit 43 in which, for example, a polymer is stretched and laminated in the prism 40, and the S-polarized light is reflected. Transparent. The transmitted P-polarized light is emitted from the exit surface 44 of the prism 40 and illuminates the reflective spatial light modulator 50. In this embodiment example, the reflection type spatial light modulator 50 is almost telecentric with respect to the x direction, which is the long side direction of the image display surface, but for the y direction, which is the short side direction, as shown in FIG. As shown, the illumination light is irradiated while being inclined outward from the center of the reflective spatial light modulator 50. As described above, the asymmetric illumination condition for the reflective spatial light modulator 50 can be easily realized by passing through the plurality of reflecting surfaces 41 and 42 each having a free-form surface.

  The illumination light reflected by the reflective spatial light modulation unit 50 enters the prism 40 again from the exit surface 44 and enters the polarization separation unit 43. Here, only the S-polarized light component of the illumination light whose polarization state is modulated for each pixel by the reflective spatial light modulator 50 is reflected and emitted from the prism 40 from the exit surface 45.

  Illumination light emitted from the exit surface 45 of the prism 40 is collimated by the collimator optical system 70 on the yz plane shown in FIG. 7 at the angle of view (that is, from each pixel of the reflective spatial light modulator 50). The light emission groups are different from each other. In the xz plane orthogonal to this, the light beam group is made into a parallel light beam group having different angles of view and enters the light guide plate 90 as shown in FIG. 8A. 7 shows typical parallel light beams LA, LB and LC in the yz plane, and FIG. 8A shows typical parallel light beams La, Lb and Lc in the xz plane.

As shown in FIG. 8A, 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 extends from the collimating optical system 70. An incident portion 91A where the emitted light is incident is used, and the other end of the optical surface 91 is an emission portion 91B where the 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 reflection type volume hologram grating 94 provided at the other end. In FIG. 8A, the luminous flux La is indicated by a broken line, Lb is indicated by a solid line, and Lc is indicated by a two-dot chain 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 Lc incident on the light guide plate 90 while being inclined toward the second reflective volume hologram grating 94 out of the parallel light La, Lb, and Lc is opposite to that. This is less than the number of reflections of the parallel light La 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. 7, incident light LA, LB, and LC having different angles of view in the yz plane are repeatedly reflected in the z direction within the light guide plate 90, but do not reflect in the y direction and reach the emitting portion 91B. To do.
This is shown in the schematic side view of FIG. 8B. As shown in FIG. 8B, the light emitted from the collimating optical system 70 is converged on the xy plane and travels in the light guide plate 90 from the incident portion 91A in the x direction. Typical incident light having different angles of view propagating through the light guide plate 90 in the xy plane is indicated by L1, L2, and L3. These lights are converged in the y direction and reflected on the optical surfaces 91 and 92 of the light guide plate 90 in the z direction, but not reflected in the y direction, and travel in the x direction. The second reflective volume hologram grating 94 The light is reflected and diffracted by the light and is emitted from the exit portion 91B to enter the observer's pupil.
In this case, as described above, since these lights are converged in the y direction, the reflection of the second reflection type volume hologram grating 94 with respect to the length of the first reflection type volume hologram grating 93 in the y direction. The diffractive surface may have a relatively short configuration.

Differences in the exit 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.
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 is considered as the exit pupil, the exit angle of the image light from the reflective spatial light modulator 50 The numerical aperture NA differs depending on, for example, the long side (x) direction and the short side (y) direction of the image display area of the spatial light modulator of the reflection type or the like, and the distance from the center of the image display area.
That is, as shown in FIG. 9, in the x direction corresponding to the long side direction of the reflective spatial light modulator 50, the light emitted from each pixel is reflected so that its principal ray is indicated by an alternate long and short dash line. It is nearly perpendicular to the display surface of the spatial light modulator 50 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. 10, 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 reflective spatial light modulation unit 50. That is, the angle formed between the display surface of the spatial light modulator 50 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 differences in the emission angles in the directions shown in FIGS. 9 and 10 are shown in Tables 1 and 2 below. In each Table 1 and Table 2, at the image height position from the optical axis, the principal ray angle that is the angle from the optical axis of the light passing through the center of each angle of view, and the upper ray angle that is the spread angle of the emitted light, and Each lower ray angle is shown.

From Table 1, 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 above-described virtual image display apparatus 200 has a configuration in which the numerical aperture NA and the emission angle have anisotropy in the x direction and the y direction will be described with reference to FIGS. 11A and 11B.
As described in FIGS. 7 and 8A, in the traveling direction corresponding to the long side direction (x direction) of the reflective spatial light modulator, the number of times of reflection in the light guide plate 90 is different depending on the angle of view, that is, the optical path. Although the lengths are different, as shown in FIG. 11A, the propagating light beams are all parallel light beams. Since the angle of view to be emitted is unchanged, the image is not disturbed. 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 reflective spatial light modulator, as shown in FIG. 11B, the upper and lower angles of view are far apart 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 L of the light guide plate needs to be, for example, about 60 mm from the average human face size. It becomes. If the light is reflected in the y direction, that is, the up and down direction inside the light guide plate 90, the upper and lower sides of the image are inverted. 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 aperture 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 reflective spatial light modulator 50.

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 luminous flux is reflected back within the light guide plate as described above.
That is, as apparent from the back ray tracing in the configuration diagram shown in FIG. 12, there is a light beam that is folded 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. 12, it is necessary to increase the apparent NAx of the illumination light. 12, parts corresponding to those in FIGS. 7, 8A and B are denoted by the same reference numerals, and redundant description is omitted.
Therefore, in this optical system, it can be seen that 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 a comparative example, FIGS. 13A and 13B show schematic configuration diagrams of a design example in which a spatial light modulation optical device is configured using one light pipe according to the illumination conditions shown in FIGS. 9 and 10 and Tables 1 and 2 described above. Show. In this example, the light source 10, the light pipe 20, the Fresnel lens 220, the diffuser plate 230, the polarization beam splitter 240, and the reflective spatial light modulator 50 are shown. In FIG. 13A, the reflective spatial light modulator is shown. In FIG. 13B, a schematic plane configuration diagram viewed from the display surface side 50, a schematic side configuration diagram is shown. The illumination conditions in this case are asymmetric in the long side direction (x direction) and the short side direction (y direction) of the reflective spatial light modulator 50. The short side direction (y direction) has a direction (angle 15.5 degrees) in which the principal ray of the display light beam emitted from the periphery of the reflective spatial light modulator 50 spreads, and the divergence angle is about 10 degrees. Small. On the other hand, in the long side direction (x direction) orthogonal to this, it is almost telecentric, but the divergence angle is relatively large at 40 degrees.

In the case of such illumination conditions, as shown in FIGS. 13A and 13B, the shape of the light pipe 20 is a direction along the long side direction and a direction along the short side direction of the reflective spatial light modulator 50. It can be seen that the width W1h of the exit surface varies greatly. In this case, since the length of the light pipe 20 is determined by the relatively large width W1h in the direction along the long side of the reflective spatial light modulator 50, the width of the exit surface is determined as 60% of the central luminance. If the design is based on%, the total length Lh becomes long as shown in FIG. 13B. Further, the curved surface shape of the exit surface in the x direction is a special shape having a very small radius of curvature as shown in FIG. 13A.
In this case, a Fresnel lens 220 and a diffusion plate 230 are provided between the light pipe 20 and the polarization beam splitter 240 to adjust the principal ray angle of incident light corresponding to the pixels of the reflective spatial light modulator 50. As a result, the assembly process of the apparatus such as the positioning of each optical component becomes complicated, and the number of components increases.
On the other hand, according to the present invention, as described above, the long side direction and the short side direction of such a reflective spatial light modulation unit can be achieved with a simple configuration of a light source and a light pipe and a prism, or only a light source and a prism. In addition, it is possible to illuminate under illumination conditions having asymmetry, and it is possible to simplify the configuration of the entire apparatus, reduce the size, and simplify the assembly work.
In addition, when the illumination under the above-mentioned illumination conditions was performed using only the light pipe, the light utilization efficiency was as low as about 35%.
On the other hand, in the spatial light modulation optical device according to the present invention, for example, when the device configuration in the first embodiment described above is used, a light utilization efficiency of 50% or more is obtained, and only the light pipe is used. In comparison, the light use efficiency can be improved by about 1.5 times or more.

[8] Eighth Embodiment Next, an embodiment of a projection type image display apparatus using the spatial light modulation optical apparatus according to the present invention will be described with reference to FIG. The projection type image display device 300 of this example uses the spatial light modulation optical device having the configuration described in the first embodiment, and includes a light source 10 such as an LED, a light pipe 20, and reflecting surfaces 41 and 42. And a prism 40 having a polarization separation unit 43, a reflective spatial light modulation unit 50, a projection optical system 310, and a screen 320. 14, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  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 the light pipe 20 that is optically adhered to the light source 10, and some of the light rays undergo total internal reflection. Thereafter, the light exits from the exit surface 22 of the light pipe 20 and enters the prism 40. In the prism 40, the illumination light is reflected by the first reflecting surface 41 and subsequently reflected by the second reflecting surface 42 that faces the first reflecting surface 41. In this embodiment, the two reflecting surfaces are so-called free-form curved reflecting surfaces having no symmetry axis in the surfaces. A free-form curved reflecting surface has a higher degree of freedom in surface shape than a toric surface and enables fine control of illumination light.

  The illumination light reflected by the two reflecting surfaces 41 and 42 is then reflected by the polarization separation unit 43 in which, for example, a polymer is stretched and laminated in the prism 40, and the S-polarized light is reflected. Transparent. The reflected S-polarized light exits from the exit surface 44 of the prism 40 to illuminate the reflective spatial light modulator 50. In this embodiment, an example in which both the x direction and the y direction are substantially telecentric is shown.

The illumination light reflected by the reflective spatial light modulation unit 50 enters the prism 40 again from the exit surface 44 and enters the polarization separation unit 43. Here, only the P-polarized light component of the illumination light whose polarization state is modulated for each pixel by the reflective spatial light modulator 50 is transmitted and exits from the prism 40 through the exit surface 45.
In this example, a case where the exit surfaces 44 and 45 are curved surfaces is shown. Thus, by making the exit surfaces 44 and 45 of the prism 40 curved, it can be optically acted on this surface. For example, in addition to the reflective surfaces 41 and 42, the exit surfaces 44 and 45 also emit light. The angle can be controlled, and the reflecting surfaces 41 and 42 can have a degree of design freedom. Further, for example, by providing the exit surface 45 with a convergence function, the diameter of the entrance pupil of the projection optical system 310 can be reduced, and the apparatus can be downsized.

The illumination light emitted from the prism 40 is projected onto the screen 320 by the projection optical system 310, and an image of the reflective spatial light modulator 50 is formed.
Also in this example, in the spatial light modulation optical device, it is possible to maintain high light utilization efficiency and simplify the configuration and reduce the size thereof. Therefore, the projection type is superior in light utilization efficiency and has a relatively simple device configuration. An image display device can be provided.

[9] Ninth Embodiment Next, an embodiment of a projection type image display apparatus using a spatial light modulation optical apparatus according to the present invention will be described with reference to FIG. The projection-type image display device 300 of this example uses the spatial light modulation optical device having the configuration described in the sixth embodiment, and includes a light source 10 such as an LED, a light pipe 20, and reflecting surfaces 41 and 42. And a prism 40 having a polarization separation unit 43, a reflective spatial light modulation unit 50, a projection optical system 310, and a screen 320. In FIG. 15, parts corresponding to those in FIG.

  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 the light pipe 20 that is optically adhered to the light source 10, and some of the light rays undergo total internal reflection. Thereafter, the light exits from the exit surface 22 of the light pipe 20 and enters the prism 40. In the prism 40, the illumination light is reflected by the first reflecting surface 41 and subsequently reflected by the second reflecting surface 42 that faces the first reflecting surface 41. In this embodiment, the two reflecting surfaces are so-called free-form curved reflecting surfaces having no symmetry axis in the surfaces. A free-form curved reflecting surface has a higher degree of freedom in surface shape than a toric surface and enables fine control of illumination light.

  The illumination light reflected by the two reflecting surfaces 41 and 42 is then reflected by the polarization separation unit 43 in which, for example, a polymer is stretched and laminated in the prism 40, and the S-polarized light is reflected. Transparent. The reflected S-polarized light exits from the exit surface 44 of the prism 40 to illuminate the reflective spatial light modulator 50. In this embodiment, an example in which both the x direction and the y direction are substantially telecentric is shown.

  The illumination light reflected by the reflective spatial light modulation unit 50 enters the prism 40 again from the exit surface 44 and enters the polarization separation unit 43. Here, only the P-polarized light component of the illumination light whose polarization state is modulated for each pixel by the reflective spatial light modulator 50 is transmitted and exits from the prism 40 through the exit surface 45. In this example, the polarization separation unit 43 is arranged to separate the illumination light in a direction orthogonal to a plane substantially along the traveling direction of the illumination light traveling in the prism 40, that is, upward in the plane of FIG. An example in which the light modulated by the reflective spatial light modulation unit 50 is transmitted from the polarization separation unit 43 and emitted from the prism 40 is shown.

The illumination light emitted from the prism 40 is projected onto the screen 320 by the projection optical system 310, and an image of the reflective spatial light modulator 50 is formed.
Also in this example, in the spatial light modulation optical device, the high light utilization efficiency can be maintained and the configuration can be simplified and downsized, so that the light utilization efficiency is excellent and the projection with a relatively simple device configuration is possible. A type image display apparatus can be provided.

As described above, according to the present invention, the spatial light modulation optical device, the virtual image display device, and the projection type image display device using the spatial light modulation optical device are excellent in light utilization efficiency as compared with the prior art and have a relatively simple device configuration. 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.

1 is a schematic configuration diagram 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. 1 is a schematic configuration diagram of an embodiment of a spatial light modulation optical device according to the present invention. 1 is a schematic configuration diagram of an embodiment of a spatial light modulation optical device according to the present invention. 1 is a schematic configuration diagram 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. 1 is a schematic configuration diagram of an embodiment of a virtual image display 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 reflection type 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 reflection type 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. A is a schematic plan view of an embodiment of a spatial light modulation optical device according to a comparative example. B is a schematic side view of an embodiment of a spatial light modulation optical device according to a comparative example. 1 is a schematic configuration diagram of an embodiment of a projection type image display device according to the present invention. 1 is a schematic configuration diagram 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 spatial light modulation optical apparatus. It is a schematic block diagram of an example of the spatial light modulation optical apparatus by a comparative example.

Explanation of symbols

  10. Light source 20, light pipe, 21. Incident surface, 22. Emission surface, 23. Side, 30. Reflective polarizing plate, 35. Diffusion unit, 40. Prism, 41. Reflective surface, 42. Reflective surface, 43. Polarization separation plane, 44. Emission surface, 45. Emission surface, 50. Reflective spatial light modulator 60. Polarizing beam splitter (PBS), 70. Collimating optical system, 80. Pupil, 90. Light guide plate, 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 (20)

A spatial light modulation optical device having a light source, a prism on which illumination light emitted from the light source is incident, and a reflective spatial light modulation unit that is illuminated by illumination light emitted from the prism,
The prism has a plurality of reflection surfaces that reflect incident illumination light, and a polarization separation unit that separates the illumination light reflected by the plurality of reflection surfaces according to the polarization component thereof,
The illumination light reflected by the reflective spatial light modulator is incident on the prism again from the same plane as the exit surface thereof, and is separated by the polarization separator according to the polarization state. Spatial light modulation optical device. The spatial light modulation optical apparatus according to claim 1, wherein a numerical aperture reduction unit for a light beam emitted from the light source is provided between the light source and the prism. The spatial light modulation optical device according to claim 2, wherein the numerical aperture reducing unit is a light pipe. The spatial light modulation optical device according to claim 2, wherein a reflective polarizing plate is provided between the numerical aperture reducing unit and the prism. The spatial light modulation according to claim 1, wherein the light source includes a plurality of light sources, and a mixing unit that mixes or mixes light beams emitted from the plurality of light sources is provided between the light sources and the prism. Optical device. The spatial light modulation optical device according to claim 5, wherein the mixing unit is a light pipe. The spatial light modulation optical apparatus according to claim 5, wherein a reflective polarizing plate is provided between the mixing unit and the prism. The spatial light modulation optical device according to claim 3 or 6, wherein the light pipe is formed integrally with the prism. The spatial light modulation optical device according to claim 8, wherein a reflective polarizing plate is provided between the light pipe and the first reflecting surface of the prism. 2. The spatial light modulation optical device according to claim 1, wherein at least one of the reflecting surfaces of the prism is a non-axisymmetric reflecting surface or a free-form reflecting surface having no symmetry axis in the surface. The polarization separation unit is arranged in an inclination direction along a traveling direction of illumination light between two reflection surfaces immediately before entering the polarization separation unit among the plurality of reflection surfaces. The spatial light modulation optical device according to 1. The polarization separation unit is arranged to separate the illumination light in a direction orthogonal to a plane substantially along the traveling direction of the illumination light traveling in the prism,
The spatial light modulation optical apparatus according to claim 1, wherein the light modulated by the reflective spatial light modulation unit is transmitted through the polarization separation unit and emitted from the prism. The spatial light modulation optical device according to claim 1, wherein a diffusing unit is provided between the light source and the reflecting surface of the prism. The spatial light modulation optical apparatus according to claim 1, wherein the polarization separation unit includes a diffusion unit on an incident side thereof. The spatial light modulation optical apparatus according to claim 1, wherein an emission surface of the illumination light of the prism is a curved surface. 2. The spatial light modulation optical device according to claim 1, wherein a surface of the prism from which illumination light reflected by the reflective spatial light modulation unit and incident on the prism again exits is a curved surface. In 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 is a spatial light modulation optical device that includes a light source, a prism on which illumination light emitted from the light source is incident, and a reflective spatial light modulation unit that is illuminated by illumination light emitted from the prism. And
The prism has a plurality of reflection surfaces that reflect incident illumination light and a polarization separation unit that separates the illumination light reflected by the plurality of reflection surfaces according to its polarization component,
Illumination light reflected by the reflective spatial light modulator is incident again on the prism from the same plane as the exit surface, separated by the polarization separator, and then incident on the virtual image optical system. Virtual image display device. In the virtual image forming optical system, the numerical aperture of the light emitted from the reflective spatial light modulator and / or the emission angle of the chief ray is different from one direction in the plane of the reflective spatial light modulator. The virtual image display device according to claim 17, wherein the virtual image display devices are different from each other in different directions. The virtual image imaging optical system includes a collimating optical system that converts light beams emitted from each pixel of the reflective spatial light modulation unit into parallel light beam groups having different traveling directions, and the parallel light beam group is incident to be totally reflected. It is composed of a light guide plate configured to exit toward the observer's pupil after propagation,
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; The virtual image display according to claim 17, further comprising: 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 the parallel light beam group in an emission region of the parallel light beam group. apparatus. In a projection-type image display device having a spatial light modulation optical device and a projection optical system that projects a display image of the spatial light modulation optical device,
The spatial light modulation optical device includes a light source, a prism on which illumination light emitted from the light source is incident, and a reflective spatial light modulation unit that is illuminated by illumination light emitted from the prism,
The prism has a plurality of reflection surfaces that reflect incident illumination light, and a polarization separation unit that separates the illumination light reflected by the plurality of reflection surfaces according to the polarization component thereof,
Illumination light reflected by the reflective spatial light modulator is incident again on the prism from the same plane as the exit surface, separated by the polarization separator, and then incident on the projection optical system. Projection type image display device.

Images