JP2010014795A - Optical apparatus and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical apparatus which uses a reflection type polarizing element and includes the reduced number of parts and to provide a projector. <P>SOLUTION: The optical apparatus includes an optical modulation element 43, a plurality of reflection prisms 441 which are respectively provided at an optical path latter stage of each optical modulation element 43 and which have an incident side end face 441A for making a light flux ejected from the optical modulation element 43 incident thereon and an ejection side inclined face 441B having inclination relative to the incident side end face 441A, two or more reflection type polarizing elements 442 which are respectively provided at an optical path latter stage of each reflection prism 441, a color synthesizing optical apparatus 5 and an adjusting prism 6 which is provided at an optical path latter stage of the color synthesizing optical apparatus 5, has an ejection side end face 61 for ejecting image light and an incident side inclined face 62 having inclination relative to the ejection side end face 61 and which makes the image light pass therethrough thereby adjusting difference of optical path length of each color light produced when passed through the reflection prism 441. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical device and a projector.

Conventionally, there has been known a projector including a light source device, a light modulation element that modulates a light beam emitted from the light source device according to image information to form image light, and a projection optical device that enlarges and projects the image light. Yes.
In such projectors, polarizing elements that transmit predetermined linearly polarized light out of the incident light flux and remove other light flux are usually arranged on the light incident side and the light emission side of the light modulation element (liquid crystal panel). (For example, see Patent Document 1).
The projector described in Patent Document 1 is configured in a single plate type using only one liquid crystal panel, and a reflective polarizing element (reflective polarizing plate) is used as a polarizing element arranged on the light emission side of the liquid crystal panel. Thus, the light resistance and heat resistance of the polarizing element disposed on the exit side are improved, and an unnecessary light beam reflected by the reflective polarizing element is not incident on the liquid crystal panel.
Specifically, in the projector described in Patent Document 1, the light beam incident side end surface orthogonal to the optical axis of the incident light beam and the exit side inclined surface inclined with respect to the light beam incident side end surface are disposed in front of the optical path of the reflective polarizing element. A first prism having a triangular cross section with a light beam exit side end surface parallel to the light beam incident side end surface and a light beam exit side end surface inclined at the rear side of the optical path of the reflective polarizing element; A second prism having a triangular cross section having an incident side inclined surface facing the inclined surface is provided, and an unnecessary light beam reflected by the reflective polarizing element is totally reflected by the light incident side end surface of the first prism. And proceed in a direction to avoid the liquid crystal panel.

International Publication WO01 / 055778

  However, when the configuration of the projector described in Patent Document 1 is applied to a three-plate projector using three liquid crystal panels, a first prism, a second prism, and a reflective polarizing element are provided for each liquid crystal panel. There is a problem that the number of parts increases.

  An object of the present invention is to provide an optical device and a projector that use a reflective polarizing element and can reduce the number of components.

  The optical device of the present invention is provided for each of a plurality of color lights, and is provided in each of a plurality of light modulation elements for modulating each color light in accordance with image information, and in a stage subsequent to the optical path of each of the light modulation elements. A plurality of reflecting prisms each having an incident side end face for receiving a light beam emitted from the light source and an exit side inclined face inclined with respect to the incident side end face; A plurality of reflective polarizing elements that transmit the first linearly polarized light out of the color light through the prism for reflection and reflect the second linearly polarized light whose polarization direction is orthogonal to the first linearly polarized light toward the reflecting prism A color synthesis optical device that forms image light by synthesizing each color light transmitted through each of the reflective polarizing elements, and an exit side end surface that is provided in the latter stage of the optical path of the color synthesis optical device and emits the image light, And said shoot An adjusting prism that has an incident-side inclined surface that is inclined with respect to a side end surface, and that adjusts a difference in optical path length generated when the image light is transmitted through the reflecting prism. It is characterized by that.

According to the present invention, when each color light emitted from the light modulation element is transmitted through each reflecting prism having an exit-side inclined surface that is inclined with respect to the incident-side end surface, a difference occurs in the optical path length depending on each position. However, an adjustment prism having an incident-side inclined surface that is inclined with respect to the exit-side end surface is provided in the latter stage of the optical path of the color synthesizing optical device. It is possible to adjust the difference in optical path length depending on each position, and to maintain good image quality.
Further, since only the reflection type polarization element and the reflection prism need be provided in the rear stage of the optical path of each light modulation element, the first prism, the second prism, and the reflection type polarization are provided in the rear stage of the optical path of each light modulation element. The number of parts can be reduced as compared with the conventional case where a plate is provided.
In addition, since the second prism can be made unnecessary as compared with the prior art, the adhesive layer formed between the second prism and the reflective polarizing element can be reduced, and the reliability of the optical device can be improved.

  The optical device of the present invention is provided for each of a plurality of color lights, and is provided in each of a plurality of light modulation elements for modulating each color light in accordance with image information, and in a stage subsequent to the optical path of each of the light modulation elements. A plurality of reflecting prisms each having an incident side end face for receiving a light beam emitted from the light source and an exit side inclined face inclined with respect to the incident side end face; A plurality of reflection types that transmit the first linearly polarized light out of the color light via the prism for reflection and reflect the second linearly polarized light whose polarization direction is orthogonal to the first linearly polarized light toward the reflecting prism. A polarizing element and a color combining optical device that combines the color lights transmitted through the reflective polarizing elements to form image light, and the color combining optical apparatus transmits the color lights transmitted through the reflective polarizing elements. Each incident light Wherein the incident surface is formed to be parallel to each of the respective exit side inclined surface of the each reflection prism.

According to the present invention, when each color light emitted from the light modulation element is transmitted through each reflecting prism having an exit-side inclined surface that is inclined with respect to the incident-side end surface, a difference occurs in the optical path length depending on each position. However, since the color combining optical device is formed so that the end surface on the light beam incident side is parallel to the inclined surface on the emission side, each color light is transmitted through this color combining optical device, so that the optical path at each position in each color light The difference in length can be adjusted, and the image quality can be maintained well.
Further, since only the reflection type polarization element and the reflection prism need be provided in the rear stage of the optical path of each light modulation element, the first prism, the second prism, and the reflection type polarization are provided in the rear stage of the optical path of each light modulation element. The number of parts can be reduced as compared with the conventional case where a plate is provided.
In addition, since the second prism can be made unnecessary as compared with the prior art, the adhesive layer formed between the second prism and the reflective polarizing element can be reduced, and the light transmittance and the reliability of the optical device can be reduced. Can be improved.

  In the optical device according to the aspect of the invention, the light modulation element is provided for each of the three color lights, and the color synthesis optical device includes the three incident-side prisms having the light beam incident-side end face and the light flux that emits the image light. Each of the incident-side prism and the emission-side prism has an X-shape in plan view with each of the light-incident-side end surfaces and the light-emitting-side end surfaces facing outward. It is preferable that the color synthesizing optical device has a shape in which a cross-sectional area cut along each plane orthogonal to the intersecting line changes along the intersecting direction of each interface.

  In the optical device according to the aspect of the invention, the light modulation element is provided for each of the three color lights, and the color synthesis optical device includes the three incident-side prisms having the light beam incident-side end face and the light flux that emits the image light. An exit-side prism having an exit-side end surface, wherein each of the entrance-side prism and the exit-side prism has an X-shape in plan view with the light-incident-side end surface and the beam-exit-side end surface facing outward. It is preferable that the color synthesizing optical device has a shape in which a cross-sectional area cut along each plane perpendicular to the intersecting line is constant along the intersecting direction of the interface.

  According to the present invention, since three light modulation elements are provided, in the conventional configuration, three second prisms are provided. However, in the present invention, all the three second prisms are unnecessary. As a result, the number of parts can be greatly reduced. Further, in the case of the conventional configuration, three adhesive layers formed between the second prism and the reflective polarizing element are provided. However, since all of these adhesive layers can be reduced, the light flux can be transmitted. Rate and the reliability of the optical device can be reliably improved.

  In the optical device according to the aspect of the invention, each of the incident-side prisms and the emission-side prism has the same shape, and is provided in the latter stage of the optical path of the color synthesis optical device, and the emission-side end surface that emits the image light, and the emission An incident-side inclined surface that is inclined with respect to the side end surface, and adjusts a difference in optical path length generated when the color light passes through the reflecting prism and the color combining optical device by transmitting the image light. It is preferable that an adjusting prism is provided.

According to the present invention, since the three incident side prisms and the emission side prism all have the same shape, manufacturing can be facilitated.
In addition, since the exit-side prism has the same shape as the entrance-side prism, when each color light passes through the exit-side prism, there is a difference in optical path length depending on each position in each color light. Since an adjusting prism having an incident-side inclined surface inclined with respect to the exit-side end surface is provided in the latter stage of the optical path of the optical device, each color light is transmitted through the adjusting prism, so that an optical path corresponding to each position in each color light. The difference in length can be adjusted, and the image quality can be maintained well.

The projector of the present invention includes a light source device, an optical device that modulates a light beam emitted from the light source device according to image information to form image light, and a projection optical device that magnifies and projects the image light. A projector, wherein the optical device is the above-described optical device.
According to the present invention, since the same configuration as described above is provided, the same effect as described above can be obtained.

[First Embodiment]
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings.
〔overall structure〕
FIG. 1 is a schematic configuration diagram illustrating a configuration of a projector according to a first embodiment.
The projector 1 modulates a light beam emitted from a light source according to image information to form image light, and enlarges and projects this image light on a screen (not shown). As shown in FIG. 1, the projector 1 includes a projection lens 2 and an optical unit 3. In addition to the projection lens 2 and the optical unit 3, the projector 1 includes a cooling unit having a cooling fan that cools each component inside the projector 1, a control device that controls each component, and the like.

The optical unit 3 optically processes the light beam emitted from the light source under the control of the control device to form image light corresponding to the image signal. As shown in FIG. 1, the optical unit 3 includes a light source device 31, an illumination optical device 32, a color separation optical device 33, a relay optical device 34, an optical device 4, and these optical components 31 to 34. 4 is disposed in a predetermined position with respect to the illumination optical axis A set inside.
As illustrated in FIG. 1, the light source device 31 includes a light source lamp 311, a reflector 312, and a concave lens 313. The light beam emitted from the light source lamp 311 is incident on the concave lens 313 by being reflected by the reflector 312, etc., is converted into parallel light substantially parallel to the illumination optical axis A by the concave lens 313, and is emitted toward the illumination optical device 32 side. The

  As shown in FIG. 1, the illumination optical device 32 includes a first lens array 321, a second lens array 322, a polarization conversion element 323, and a superimposing lens 324. The light beam emitted from the light source device 31 is divided into a plurality of partial light beams by the first lens array 321 and forms an image near the second lens array 322. Each partial light beam emitted from the second lens array 322 is incident so that its central axis (principal ray) is perpendicular to the incident surface of the polarization conversion element 323. It is emitted as linearly polarized light. A plurality of partial light beams emitted as linearly polarized light from the polarization conversion element 323 and passed through the superimposing lens 324 are superimposed on three liquid crystal panels 43 (to be described later) of the optical device 4.

As shown in FIG. 1, the color separation optical device 33 includes two dichroic mirrors 331 and 332 and a reflection mirror 333, and is emitted from the illumination optical device 32 by the dichroic mirrors 331 and 332 and the reflection mirror 333. In addition, it has a function of separating a plurality of partial light beams into three color lights of red, green, and blue.
As shown in FIG. 1, the relay optical device 34 includes an incident side lens 341, a relay lens 343, and reflection mirrors 342 and 344, and the color light separated by the color separation optical device 33, for example, red light, is optical device 4. Of the liquid crystal panel 43R on the red light side, which will be described later.
The optical device 4 modulates the incident light flux of each color according to image information to form image light of each color, and combines the image light of each color to form image light. A specific configuration of the optical device 4 will be described later.
The projection lens 2 is configured as a combined lens obtained by combining a plurality of lenses, and enlarges and projects the image light emitted from the optical device 4 on the screen.

[Configuration of optical device]
2 is a side view of the optical device 4 showing the arrangement of the liquid crystal panels 43R and 43B, the cross dichroic prism 5, and the like. FIG. 3 is a side view of the optical device 4 showing the arrangement of the liquid crystal panel 43G, the cross dichroic prism 5, and the like. is there.
2 and 3, the optical device 4 includes a field lens 41, an incident side polarization element 42, and a liquid crystal panel 43 as a light modulation element (a red light side liquid crystal panel 43R, a green light side liquid crystal panel). 43G and a blue light side liquid crystal panel 43B), an exit side polarization element 44, a cross dichroic prism 5 as a color synthesizing optical device, and an adjustment prism 6.
In the present embodiment, the dichroic mirror 332 and the reflecting mirrors 333 and 344 are arranged to be inclined with respect to the illumination optical axis A so as to reflect the incident light beam upward, and for modulating and emitting the light beam. As shown in FIGS. 2 and 3, the optical components 2 and 41 to 44 are arranged above the dichroic mirror 332 and the reflection mirrors 333 and 344 (upper in FIGS. 2 and 3).

The field lens 41 converts each partial light beam emitted from the illumination optical device 32 and reflected by the dichroic mirror 332 and the reflection mirrors 333 and 344 into parallel light parallel to the illumination optical axis A.
The incident side polarization element 42 transmits only linearly polarized light having a polarization direction substantially the same as the polarization direction aligned by the polarization conversion element 323, and reflects linearly polarized light orthogonal to the direction.
The liquid crystal panel 43 has a configuration in which a liquid crystal as an electro-optical material is hermetically sealed between a pair of rectangular substrates in a plan view made of glass or the like, and is emitted from the incident-side polarizing element 42 under the control of the control device. The polarization direction of the polarized light beam is modulated.

The exit side polarization element 44 transmits only the first linearly polarized light in the polarization direction orthogonal to the transmission axis of the entrance side polarization element 42 out of the light flux emitted from the liquid crystal panel 43. As shown in FIG. 2, the exit side polarization element 44 includes a reflection prism 441 and a reflection type polarization element 442.
The reflecting prism 441 is formed in a columnar shape with a right-angled triangle cross section, and has an incident-side end surface 441A, a hypotenuse with a substantially right-angled cross-section, an exit-side inclined surface 441B inclined with respect to the incident-side end surface 441A, and a light beam incident side It includes an end face 431A and an end face 441C arranged with a 90-degree apex angle therebetween. The reflecting prism 441 is arranged so that the incident-side end surface 441A is orthogonal to the illumination optical axis A.

  The reflective polarizing element 442 is provided on the exit-side inclined surface 441B, transmits the first linearly polarized light, and reflects the second linearly polarized light whose polarization direction is orthogonal to the first linearly polarized light. The reflective polarizing element 442 is composed of fine linear ribs such as aluminum formed in parallel on the exit side inclined surface 441B. The reflective polarizing element 442 transmits the first linearly polarized light having a polarization direction parallel to the direction in which the linear rib extends, and reflects the second linearly polarized light having a perpendicular polarization direction.

A light beam emitted from the liquid crystal panel 43 and incident on the exit-side polarizing element 44 is emitted from the exit-side polarizing element 44 as follows.
That is, as shown in FIG. 2, the light beam emitted from the liquid crystal panel 43 first enters the reflecting prism 441 from the incident-side end surface 441A, exits from the emitting-side inclined surface 441B, and enters the reflective polarizing element 442. To do. Of the light flux incident on the reflective polarizing element 442, the first linearly polarized light passes through the reflective polarizing element 442 and enters the cross dichroic prism 5. At this time, each color light incident on the cross dichroic prism 5 is refracted by the reflecting prism 441. Further, the reflecting prism 441 is formed in a right-angled triangle in cross section, and the thickness of each part is different with respect to the traveling direction of the light beam. Therefore, the light path length of the light beam transmitted through the reflecting prism 441 varies depending on each position. It will be.
On the other hand, among the light beams incident on the reflective polarizing element 442, the second linearly polarized light is reflected to the light incident side by the reflective polarizing element 442 and totally reflected on the incident-side end surface 441A, as shown in FIG. Thereafter, the light is emitted from the end face 441C in a direction avoiding the liquid crystal panel 43. An antireflection film (not shown) that prevents the reflection of the second linearly polarized light is formed on the end surface 441C.

  The cross dichroic prism 5 combines the color lights transmitted through the exit-side polarization elements 44 to form image light. As shown in FIG. 1, the cross dichroic prism 5 includes three right-sided prismatic incident side prisms 51R, 51G, and 51B each having a light beam incident side end surface 511 on which each color light is incident on the bottom surface, and image light on the bottom surface. The right-sided triangular prism-shaped exit-side prism 51S having a light-beam exit-side end surface 512 that emits light is bonded to each other along each interface with the apex angles as centers, and each bottom surface portion is formed in a cubic shape facing outward. . Each prism 51R, 51G, 51B, 51S has an equal refractive index. In addition, four dielectric multilayer films 513 that are reflective surfaces are formed in an X shape in plan view along the interfaces. Among these dielectric multilayer films 513, a set of dielectric multilayer films 513 along one X-shaped extending direction and a set of dielectric multilayer films along the other X-shaped extending direction The film 513 is configured to reflect light beams in different wavelength ranges. That is, the two sets of dielectric multilayer films 513 transmit G light from the liquid crystal panel 43G and reflect R and B light from the liquid crystal panels 43R and 43B. Thereby, image light is formed. The adjustment prism 6 is attached to the exit surface 512 of the exit side prism 51S by bonding or the like.

  The adjustment prism 6 has a refractive index equal to that of the exit-side prism 51S and is formed in a right triangular prism shape having the same size as the reflecting prism 441 as shown in FIG. The adjustment prism 6 has an exit-side end face 61 that emits image light, and an entrance-side inclined face 62 that is inclined with respect to the exit-side end face 61 and attached to the exit-side prism 51S. In such an adjusting prism 6, the exit-side end surface 61 rotates 180 degrees around the central axis of the incident light beam with respect to the exit-side inclined surface 441B of the reflecting prism 441 provided in the preceding stage of the optical path of the incident-side prism 51G. In a posture having symmetry, and along the direction of the intersecting line K (see FIG. 1) of the two sets of dielectric multilayer films 513, the cross section cut at each plane orthogonal to the intersecting line K changes. In such a posture, it is attached to the exit side prism 51S. The adjusting prism 6 adjusts the optical path length of each position of image light emitted from the exit-side prism 51S and having different optical path lengths depending on the positions so that the optical path lengths are equal at any position. The image light adjusted so that the optical path lengths at the respective positions are equalized by the adjusting prism 6 is emitted from the emission side end face 61 and is refracted and emitted from the projection lens 2.

[Effect of this embodiment]
According to the above embodiment, the following effects are obtained.
Each color light emitted from each liquid crystal panel 43 has a difference in optical path length depending on each position when passing through each reflecting prism 441 having an exit side inclined surface 441B inclined with respect to the incident side end surface 441A. In the present embodiment, the adjustment prism 6 having the incident-side inclined surface 62 inclined with respect to the emission-side end surface 61 is provided in the latter stage of the optical path of the cross dichroic prism 5, so that each color light is transmitted through the adjustment prism 6. By doing so, the difference in optical path length depending on each position in each color light can be adjusted, and the image quality can be maintained satisfactorily.
Further, since only the reflective polarizing element 442 and the reflecting prism 441 need be provided in the subsequent stage of the optical path of each liquid crystal panel 43, the first prism, the second prism, and the reflective are provided in the subsequent stage of the optical path of each liquid crystal panel 43. The number of parts can be reduced as compared with the conventional case where a type polarizing element is provided.
In addition, since the second prism can be made unnecessary as compared with the prior art, the adhesive layer formed between the second prism and the reflective polarizing element can be reduced, and the reliability of the optical device can be improved.

[Second Embodiment]
Next, a projector 1A according to the second embodiment will be described.
FIG. 4 is a schematic configuration diagram showing the configuration of the projector 1A according to the second embodiment.
The projector 1A of the present embodiment has the same configuration as that of the first embodiment, but in the embodiment, the adjustment prism 6 is provided on the light emission side of the cross dichroic prism 5, but in this embodiment, the adjustment prism 6 is provided. The adjustment prism portion 52 as the adjustment prism is different from the first embodiment in that it is provided on each light beam incident side of the cross dichroic prism 5A.

FIG. 5 is an enlarged view showing the optical device 4A, and FIG. 6 is a side view showing the optical device 4A.
That is, in this embodiment, as shown in FIGS. 5 and 6, the adjustment prism portion 52 is formed so as to protrude outward on each light beam incident side of each incident side prism 51R, 51G, 51B. The dichroic prism 5 </ b> A includes a cubic main body 50 and an adjustment prism 52 that protrudes outward from the main body 50. Each adjustment prism unit 52 includes a light incident side end face 511 on which the light exiting polarizing element 44 is attached by bonding or the like, and the light emitted from the light emitting side polarizing element 44 is incident thereon. That is, the cross dichroic prism 5A is formed so that the light beam incident side end surface 511 is parallel to the exit side inclined surface 441B of the reflecting prism 441. The cross dichroic prism 5A is formed in a shape in which the cross section cut along each plane perpendicular to the intersecting line K changes along the intersecting line K direction of the two sets of dielectric multilayer films 513.

Also in this embodiment, the difference in optical path length caused by each position in the light beam when passing through the reflecting prism 441 can be adjusted by the adjusting prism unit 52, so that the image quality can be maintained well. The same effect as the embodiment can be obtained. Further, since the adhesive layer in the optical path can be reduced, the light transmittance can be improved.
In addition, since the reflecting prism 441 is bonded to each adjustment prism unit 52 via the exit-side polarizing element 44, the light-incident-side end surface 511 of the adjustment prism unit 52 and the exit-side inclined surface 441B of the reflecting prism 441 are disposed. It is possible to cancel the refraction of the luminous flux. Therefore, each optical component 2, 31-34, 4A can be arrange | positioned in the same plane, and optical design can be made easy.

[Third Embodiment]
Next, an optical device 4B according to a third embodiment will be described.
FIG. 7 is a side view showing an optical device 4B according to the third embodiment.
The optical device 4B of the present embodiment has the same configuration as that of the second embodiment, but in the second embodiment, the adjustment prism portion 52 is along the direction of the intersection line K of the two sets of dielectric multilayer films 513. In this embodiment, the cross section cut at each plane orthogonal to the intersection line K is formed in a shape that changes. However, in this embodiment, the adjustment prism portion 52 has a cross section cut at each plane orthogonal to the intersection line K. The difference from the second embodiment is that the reflecting prism 441B is arranged in a uniform shape and the arrangement direction of the reflecting prism 441B in accordance with the shape of the adjusting prism portion 52.

In the present embodiment, a prism portion 52A having the same shape as the adjustment prism portion 52 is also formed on the exit side of the exit side prism 51S. That is, the prisms 51R, 51G, 51B, 51S have the same shape, and form a cubic prism 53. An adjustment prism 6A for adjusting a difference in optical path length caused by each position in the light beam when passing through the prism portion 52A is provided on the light beam exit side end surface 515 of the prism portion 52A by bonding or the like. . The adjustment prism 6A has an exit-side end face 61A that emits image light, and an entrance-side inclined face 62A that is inclined with respect to the exit-side end face 61A and attached to the prism portion 52A.
In this embodiment as well, the optical components 2, 31 to 34, 4B that can maintain good image quality as in the second embodiment can be arranged in the same plane, and optical design can be facilitated. In addition to the effects, the prisms 51R, 51G, 51B, and 51S have the same shape, and therefore can be manufactured easily.

[Fourth Embodiment]
Next, an optical device 4C according to a fourth embodiment will be described.
FIG. 8 is a side view showing an optical device 4C according to the fourth embodiment.
The optical device 4C of this embodiment is characterized in that the cross dichroic prism 5C has a configuration in which the prism portion 52A and the adjustment prism 6A are omitted from the cross dichroic prism 5B of the third embodiment.
Even in this embodiment, the prisms 51R, 51G, 51B, and 51S do not have the same shape, but the same effects as those of the third embodiment can be obtained, and the prism portion 52A and the adjusting prism 6A are omitted. Therefore, downsizing can be achieved.

[Fifth Embodiment]
Next, a projector 1D according to a fifth embodiment will be described.
FIG. 9 is a schematic configuration diagram showing a projector 1D according to the fifth embodiment.
The projector 1D of the present embodiment has the same configuration as that of the first embodiment, but in the first embodiment, the adjustment prism 6 is along the intersecting line K direction of the two sets of dielectric multilayer films 513. In the present embodiment, the adjustment prism 6 is formed along the direction of the intersecting line K of the two sets of dielectric multilayer films 513, although the cross section cut at each plane orthogonal to the intersecting line K is formed to change. The difference is that the cross section cut along each plane orthogonal to the intersecting line K is formed into a constant shape.
In this embodiment as well, the same effects as in the first embodiment can be obtained, and the emission direction of the light beam from the adjustment prism 6 and the traveling direction of the adjustment prism 6 in the previous stage of the optical path are in the same plane. Therefore, the optical components 2, 31 to 34, 4D can be arranged in the same plane.

[Modification of Embodiment]
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
In the embodiment, the adjustment prism 6 and the cross dichroic prism 5 are provided separately, but may be formed integrally.
In each of the above embodiments, the configuration of the reflective polarizing element 442 is not limited to the configuration described in each of the above embodiments, and any configuration may be used as long as it is a reflective polarizer.
For example, as the reflective polarizing element 442, a polarized light separating element formed of a dielectric multilayer film, a polymer-based layered structure in which organic materials having refractive index anisotropy (birefringence) such as a liquid crystal material are stacked in layers Polarizing plate, optical element combining λ / 4 phase difference plate and circularly polarized reflector that separates unbiased light into clockwise circularly polarized light and counterclockwise circularly polarized light, reflected polarized light using Brewster angle An optical element that separates light into transmitted polarized light or a hologram optical element that uses a hologram may be employed.
In each of the embodiments, only the example of the front projection type projector has been described. However, the present invention is also applicable to a rear type projector that includes a screen and performs projection from the back side of the screen.

  INDUSTRIAL APPLICABILITY The present invention uses a reflective polarizing element and can reduce the number of parts, and thus can be used for a light modulation device for a projector used in presentations and home theaters.

1 is a schematic configuration diagram showing a projector according to a first embodiment. The side view of the optical apparatus which shows arrangement | positioning of the liquid crystal panel in the said embodiment, a cross dichroic prism, etc. The side view of the optical apparatus which shows arrangement | positioning of the other liquid crystal panel, cross dichroic prism, etc. in the said embodiment. The schematic block diagram which shows the structure of the projector which concerns on 2nd Embodiment. The enlarged view which shows the optical apparatus in the said embodiment. The side view which shows the optical apparatus in the said embodiment. The side view which shows the optical apparatus which concerns on 3rd Embodiment. The side view which shows the optical apparatus which concerns on 4th Embodiment. FIG. 10 is a schematic configuration diagram showing a projector according to a fifth embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,1A, 1D ... Projector, 2 ... Projection lens (projection optical device), 5, 5A-5C ... Cross dichroic prism (color synthesis optical device), 6, 6A ... Adjustment prism, 31 ... Light source device, 43 ... Liquid crystal panel (Light modulation element), 61... Exit side end face, 62... Incident side inclined face, 441... Reflecting prism, 441 A... Incident side end face, 442.

Claims (6)

A plurality of light modulation elements which are provided for each of a plurality of color lights and modulate each of the color lights according to image information;
A plurality of reflecting prisms provided on the latter stage of the optical path of each of the light modulation elements, each having an incident side end face on which a light beam emitted from the light modulation element is incident, and an emission side inclined face inclined with respect to the incident side end face When,
The second linearly polarized light, which is provided in the latter stage of the optical path of each of the reflecting prisms, transmits the first linearly polarized light out of the colored light passing through the reflecting prism, and has a polarization direction orthogonal to the first linearly polarized light. A plurality of reflective polarizing elements that reflect toward the reflecting prism;
A color synthesizing optical device for synthesizing the color lights transmitted through the reflective polarizing elements to form image light;
The color combining optical device includes an emission side end surface that emits the image light and an incident side inclined surface that is inclined with respect to the emission side end surface, and transmits each of the colors by transmitting the image light. An optical device comprising: an adjusting prism that adjusts a difference in optical path length generated when light passes through the reflecting prism. A plurality of light modulation elements which are provided for each of a plurality of color lights and modulate each of the color lights according to image information;
A plurality of reflecting prisms provided on the latter stage of the optical path of each of the light modulation elements, each having an incident side end face on which a light beam emitted from the light modulation element is incident, and an emission side inclined face inclined with respect to the incident side end face When,
The second linearly polarized light that is provided in the latter stage of the optical path of each of the reflecting prisms, transmits the first linearly polarized light out of the colored light that has passed through the reflective prism, and the polarization direction is orthogonal to the first linearly polarized light. A plurality of reflective polarizing elements that reflect light toward the reflecting prism;
A color synthesizing optical device that synthesizes each color light transmitted through each reflective polarizing element to form image light,
The color synthesizing optical device is formed so that each light beam incident side end surface on which each color light transmitted through each reflective polarizing element is incident is parallel to each exit side inclined surface of each reflective prism. An optical device characterized by the above. The optical device according to claim 2.
The light modulation element is provided for each of the three color lights,
The color synthesizing optical device includes three incident side prisms having the light beam incident side end surface, and an emission side prism having a light beam emission side end surface for emitting the image light,
Each of the incident-side prisms and the exit-side prisms are combined such that each of the light beam incident side end surfaces and the light beam output side end surfaces face outward and each interface has an X shape in plan view.
The color synthesizing optical device has a shape in which a cross-sectional area cut along each plane orthogonal to the intersecting line changes along the intersecting direction of each interface. The optical device according to claim 2.
The light modulation element is provided for each of the three color lights,
The color synthesizing optical device includes three incident side prisms having the light beam incident side end surface, and an emission side prism having a light beam emission side end surface for emitting the image light,
Each of the incident side prisms and the exit side prisms are combined such that the light beam incident side end surface and the light beam exit side end surface face outward and each interface has an X shape in plan view.
The color synthesizing optical device has a shape in which a cross-sectional area cut along each plane perpendicular to the intersection line is constant along a direction of intersection of the interfaces. The optical device according to claim 4.
Each of the incident side prisms and the exit side prism has the same shape,
Each color synthesis optical device has an emission-side end surface that emits the image light and an incident-side inclined surface that is inclined with respect to the emission-side end surface and transmits the image light. An optical device comprising: an adjusting prism that adjusts a difference in optical path length generated when light is transmitted through the reflection prism and the color synthesis optical device. A projector comprising: a light source device; an optical device that modulates a light beam emitted from the light source device according to image information to form image light; and a projection optical device that magnifies and projects the image light,
The projector according to any one of claims 1 to 5, wherein the optical device is the optical device according to any one of claims 1 to 5.

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