JP2008158274A - projector - Google Patents

Abstract

To provide a projector capable of easily reducing left and right color unevenness while suppressing an increase in size such as a thickness of the projector.
In a long optical path with relay lenses 45 and 46, red light LR is bent three times in total by red reflecting mirrors 42c, 42d and 42e. The illumination light image of the red light LR is upside down when compared with the illumination light images of the blue light LB and the green light LG, but is not reversed left and right. Therefore, the directions in which the illumination lights of the blue light LB, the green light LG, and the red light LR are finally combined coincide with each other in the left-right direction, and color unevenness is less likely to occur in the left-right direction.
[Selection] Figure 1

Description

The present invention relates to a projector that modulates illumination light using a liquid crystal light valve or the like and projects the modulated image light.

As a conventional general projector, a light source that generates substantially white light, an illumination optical system that uniformizes and converts the light from the light source, and color separation that separates the light that has passed through the illumination optical system into three color optical paths An optical system, three liquid crystal panels that are respectively illuminated by three colors of illumination light, a cross dichroic prism that synthesizes images from these three liquid crystal panels, and a projection lens that projects a magnified image after synthesis There is.

In some projectors as described above, a combination mirror obtained by joining two mirrors is disposed on an optical path of a relay system that is longer than the optical paths of other colors, and the illumination light image is inverted upside down. (See Patent Document 1).

Further, in a similar projector, there is a projector in which an illumination light image is vertically and horizontally reversed by three-dimensionally arranging a mirror system including four total reflection mirrors on a relay optical path (Patent Document). 2).
JP-A-2005-17772 JP-A-10-205816

However, in the former projector using a combination mirror, since the illumination light image is not reversed horizontally, it is not easy to eliminate color unevenness that occurs on the left and right of the projection image. In particular, PB for polarization conversion
The illuminance distribution tends to occur in the horizontal direction due to the vignetting of the light flux generated in the S array, and the screen projected on the screen is often long in the left and right directions. It has become. Note that the projector as described above also has a problem that the connection portion of the combination mirror is projected as a shadow on the screen.

Further, in the former projector in which the four total reflection mirrors are arranged in three dimensions, it is inevitable that the long optical path portion including the relay system becomes large, and there is a problem that the projector becomes particularly large in the thickness direction. .

Therefore, an object of the present invention is to provide a projector that can easily reduce left and right color unevenness while suppressing an increase in size such as the thickness of the projector.

In order to solve the above problems, a projector according to the present invention includes (a) an illumination device that emits illumination light, (b) a color separation optical system that separates illumination light from the illumination device into three colors, and three-color light. A relay optical system that transmits an illumination light image while being inverted in one optical path for a predetermined color that is longer than the optical paths for the other colors, and a bending of the optical path for the predetermined color. A color separation light guide optical system including a reflection element system that horizontally inverts an illumination light image to be inverted by the system, and (c) light guided to an optical path for each color light separated by the color separation light guide optical system The
A liquid crystal light valve for each color light that is modulated according to image information, (d) a light combining optical system that combines the image light of each color modulated by the liquid crystal light valve, and (e) an image light that has passed through the light combining optical system. A projection optical system for projecting.

In the projector described above, the reflective element system of the color separation light guide optical system reverses the illumination light image to be inverted by the relay optical system by bending the optical path for the predetermined color longer than the other, so that the illumination light of the predetermined color The image and the illumination light images for other colors can be made to coincide with each other in the left-right direction, and color unevenness in the projected image can be reduced in the left-right direction with high importance.

Further, according to a specific aspect or aspect of the present invention, in the projector, the number of reflections in the color separation light guiding optical system and the light combining optical system regarding the optical path for a predetermined color is the color separation regarding the optical path for other colors. This is an odd number of times more than the number of reflections in the light guide optical system and the light combining optical system. In this case, the horizontal reversal of the illumination light image can be adjusted by comprehensively taking into account the color separation light guide optical system and the light combining optical system.

According to another aspect of the present invention, the color separation light guide optical system includes two dichroic mirrors arranged along the optical path as the color separation optical system. Then, one of the optical paths for the other colors is optically bent by the upstream dichroic mirror, is bent again by the additional mirror for optical path bending, and is bent in the light combining optical system. Then, the other of the optical paths for the other colors is optically bent by a downstream dichroic mirror and guided to the light combining optical system from a direction in which it goes straight in the light combining optical system. An optical path for a predetermined color goes straight through the two dichroic mirrors, and is guided to the light combining optical system from a direction in which it is bent in the light combining optical system via the relay optical system and the reflecting element system. In this case, the color separation light guide optical system can be assembled in a relatively simple structure.

According to still another aspect of the present invention, the reflective element system is composed of three reflective elements. In this case, the reflection element system can be configured with a relatively small number of reflection elements such as mirrors. further,
Since the optical path for a predetermined color can be easily lengthened by three reflecting elements, the lenses constituting the relay optical system can have a relatively low refractive index and a low curvature, thereby easily achieving aberration reduction, cost reduction, etc. it can.

According to still another aspect of the present invention, the reflection element system includes any one of a reflection element including only a mirror and a reflection element including a polarization beam splitter, a phase difference plate, and a mirror.

According to still another aspect of the present invention, the illumination optical axes of the three-color optical paths are arranged on the same plane. In this case, the projector can be made thin with respect to the plane including the illumination optical axis, and the projector can be kept thin.

According to still another aspect of the present invention, the illumination optical axes of the optical path for a predetermined color intersect on the same plane. In this case, the optical path for a predetermined color can be incorporated in the projector in a space-saving manner.

[First Embodiment]
FIG. 1 is a conceptual diagram illustrating the configuration of the optical system of the projector according to the first embodiment of the invention.

The projector 10 is an optical device for modulating a light beam emitted from a light source according to image information to form a color optical image and enlarging and projecting the optical image on a screen. The illumination optical system 30, the color separation light guide optical system 40, the light modulator 60, the cross dichroic prism 70, and the projection optical system 80 are configured. Here, the light source lamp unit 20 and the illumination optical system 30 constitute an illumination device that generates illumination light to be incident on the color separation light guide optical system 40 and the like.

The light source lamp unit 20 is a light source device that collects and emits light beams emitted from the lamp body 21 to the surroundings and illuminates the light modulation unit 60 via the illumination optical system 30 and the like. The light source lamp unit 20 reflects a lamp main body 21 that is an arc tube, a spherical secondary mirror 22 that reflects light source light emitted forward from the lamp main body 21, and light source light emitted rearward from the lamp main body 21. An ellipsoidal main mirror 23 and a collimating concave lens 24 are provided. In the light source lamp unit 20, the substantially white light source light emitted from the lamp body 21 is incident on the primary mirror 23 via the secondary mirror 22 or directly and reflected forward, and is collimated by the concave lens 24. In this state, the light is emitted to the illumination optical system 30 side. In addition, although the high-pressure mercury lamp is normally used for the lamp body 21 described above in that high-intensity light can be emitted over the wavelength of each color, the lamp that can be incorporated in the light source lamp unit 20 is: Not only a high pressure mercury lamp but various light emitting lamps can be used, and a solid light emitting element such as an LED can be obtained. The primary mirror 2
As 3, various reflectors such as a paraboloid can be used without being limited to an elliptical surface. When the parabolic main mirror 23 is used, a parallel light beam can be emitted from the light source lamp unit 20 without providing the concave lens 24 or the like after the main mirror 23.

The illumination optical system 30 divides the light beam emitted from the light source lamp unit 20 into a plurality of partial light beams and makes the illumination light uniform by superimposing it on a target illumination area and polarizing the illumination light in a specific direction. The first multi-lens 31, the second multi-lens 32, the polarization conversion device 34, and the superimposing lens 35 are provided.

The first multi-lens 31 is also called a lens array, and has a function as a light beam splitting optical element that splits a light beam emitted from the lamp body 21 into a plurality of partial light beams, and has a system optical axis OA.
Are provided with a plurality of small lenses arranged in a matrix in a plane orthogonal to. The contour shape of each small lens is a liquid crystal display panel 61b, 61g, which constitutes a light modulation unit 60 described later.
It is set so as to be almost similar to the shape of the image forming area 61r. The second multi-lens 32 is an optical element that condenses a plurality of partial light beams divided by the first multi-lens 31 described above. The second multi-lens 32 is similar to the first multi-lens 31 in the system optical axis O.
A plurality of small lenses arranged in a matrix form in a plane orthogonal to A are provided, but for the purpose of condensing, the contour shape of each small lens is the image forming area of the liquid crystal display panels 61b, 61g, 61r. It is not necessary to correspond exactly to the shape of. The first and second multi-lenses 31 and 32 and the superimposing lens 35 described below function as an optical integrator that equalizes incident light by dividing and superimposing it.

The polarization conversion device 34 is formed of a PBS array and a phase difference plate, and has a role of aligning the polarization direction of each partial light beam divided by the first multi-lens 31 with one direction of linearly polarized light.
Although detailed illustration of the PBS array of the polarization converter 34 is omitted, the system optical axis O
A configuration in which polarization separation films and reflection mirrors that are inclined with respect to A are alternately arranged.
The former polarization separation film transmits one polarized light beam among the P-polarized light beam and S-polarized light beam included in each partial light beam, and reflects the other polarized light beam. The reflected other polarized light beam is bent by the latter reflecting mirror, and is emitted in the emission direction of the one polarized light beam, that is, the direction along the system optical axis OA. One of the emitted polarized light beams is polarized and converted by a phase difference plate provided in a stripe shape on the light beam emission surface of the polarization conversion device 34, and the polarization directions of all the polarized light beams are aligned. By using such a polarization conversion device 34, the light beam emitted from the lamp body 21 can be aligned with a polarized light beam in one direction, so that the utilization factor of the light source light used in the light modulation unit 60 is improved. Can do.

The superimposing lens 35 condenses a plurality of partial light beams that have passed through the first multilens 31, the second multilens 32, and the polarization converter 34, and superimposes them on the image forming regions of the liquid crystal display panels 61b, 61g, 61r. Is an optical element. The light beam emitted from the superimposing lens 35 is emitted to the color separation light guide optical system 40 at the next stage while being made uniform. In other words, the illumination light that has passed through both the multi-lenses 31 and 32 and the superimposing lens 35 passes through the color separation light guide optical system 40 described in detail below, and the illumination region of the light modulation unit 60, that is, the liquid crystal display panels 61b and 61g for the respective colors. ,
The 61r image forming area is uniformly superimposed and illuminated.

The color separation light guide optical system 40 includes first and second dichroic mirrors 41a and 41b, a blue reflection mirror 42a, a red reflection mirror 42c, 42d and 42e, and a field lens 43b.
, 43g, 43r, and relay lenses 45, 46. Of these, the first and second
The dichroic mirrors 41a and 41b constitute a color separation optical system for separating substantially white illumination light into three primary colors. Each dichroic mirror 41a, 41b is an optical element obtained by forming on a transparent substrate a dielectric multilayer film having a wavelength selection function of reflecting a light beam in a predetermined wavelength region and transmitting a light beam in another wavelength region. Yes, they are arranged in an inclined state with respect to the system optical axis OA. The first dichroic mirror 41a reflects the blue light LB among the three colors of blue, green, and red (B, G, and R), and transmits the green light LG and the red light LR. The second dichroic mirror 41b reflects the green light LG out of the incident green light LG and red light LR and transmits the red light LR. As a result, the illumination light that has entered the color separation light guide optical system 40 from the light source lamp unit 20 through the illumination optical system 30 is reflected by the first dichroic mirror 41a and guided to the first optical path OP1 extending beyond the blue light. Light LB, green light LG that is transmitted through the first dichroic mirror 41a, reflected by the second dichroic mirror 41b, and guided to the second optical path OP2 that extends beyond the light LB, and transmitted through the first and second dichroic mirrors 41a and 41b Then, the light is separated into the red light LR guided to the third optical path OP3 extending ahead.

Field lenses 43b and 43g for each color provided on the exit side of the color separation light guide optical system 40
, 43r are the partial light beams emitted from the second multi-lens 32 and incident on the light modulation unit 60.
It is provided so as to have an appropriate degree of convergence. The pair of relay lenses 45 and 46 are disposed on the third optical path OP3 for red which is relatively longer than the first optical path OP1 for blue and the second optical path OP2 for green. These relay lenses 45 and 46 are the first relay lens 4 on the incident side.
The image formed immediately before 5 is inverted as it is and transmitted to the field lens 43r on the exit side, thereby preventing a decrease in light use efficiency due to light diffusion or the like. The blue reflection mirror 42a, as an additional mirror, returns the blue light LB folded back in the orthogonal direction by the first dichroic mirror 41a to the liquid crystal display panel 61b side again in the orthogonal direction. The red reflection mirrors 42c, 42d, and 42e function as a reflection element system, and the red light LR that has passed through the first and second dichroic mirrors 41a and 41b is folded back three times to form a liquid crystal display panel 61r. Lead to the side. In this case, the optical path OP1 of the blue light LB and the red light LR
OP3 is parallel to the paper surface along with the optical path OP2 of the green light LG. That is, each optical path O
The system optical axes OA for the respective colors corresponding to P1 to OP3 are stored in a common plane and are two-dimensionally arranged. Here, the third optical path OP3 corresponds to an optical path for a predetermined color and is used for red in this embodiment, and the first optical path OP1 corresponds to one of the optical paths for other colors. In this embodiment, it is for blue, and the second optical path OP2 corresponds to one of the optical paths for other colors, and in this embodiment is for green.

The light modulation unit 60 includes three liquid crystal display panels 61b, 61g, and 61r on which illumination lights LB, LG, and LR of three colors are incident, respectively. Here, the liquid crystal display panel 61b for blue light LB and the pair of polarization filters 62b and 62b sandwiching the liquid crystal display panel 61b constitute a liquid crystal light valve for two-dimensionally modulating the luminance of illumination light based on image information. . The liquid crystal display panel 61g for green light LG and the pair of polarizing filters 62g and 62g sandwiching the liquid crystal display panel 61g also constitute a green liquid crystal light valve, and similarly, a pair of liquid crystal display panel 61r for red light LR and a pair. The polarizing filters 62r and 62r also constitute a red liquid crystal light valve. Each liquid crystal display panel 61b, 6
1g and 61r are liquid crystal which is an electro-optical material hermetically sealed between a pair of transparent glass substrates. For example, a polarized light beam incident on each of them according to a given image signal using a polysilicon TFT as a switching element. Modulate the polarization direction.

The blue light LB guided to the first optical path OP1 enters the illumination area of the liquid crystal display panel 61b via the blue reflection mirror 42a and the field lens 43b, and illuminates the image forming area in the liquid crystal display panel 61b. The green light LG guided to the second optical path OP2 is the field lens 43.
It enters the illumination area of the liquid crystal display panel 61g via g and illuminates the image forming area in the liquid crystal display panel 61g. The red light LR guided to the third optical path OP3 is emitted from the first and second relay lenses 4.
5, 46, the red reflecting mirrors 42c, 42d, and 42e, and the field lens 43r enter the illumination area of the liquid crystal display panel 61r to illuminate the image forming area in the liquid crystal display panel 61r. Each of the liquid crystal display panels 61b, 61g, and 61r is a non-light-emitting and transmissive light modulation device for changing the spatial distribution of the polarization direction of incident illumination light. Each liquid crystal display panel 61
Each of the color lights LB, LG, and LR incident on b, 61g, and 61r is supplied to each liquid crystal display panel 6.
According to the drive signal or control signal input as an electrical signal to 1b, 61g, 61r,
The polarization state is adjusted on a pixel basis. At that time, the polarization direction of the illumination light incident on the liquid crystal display panels 61b, 61g, 61r is adjusted by the polarizing filters 62b, 62g, 62r, and the liquid crystal display panels 61b, 62r, 62r are adjusted by the polarizing filters 62b, 62g, 62r. 6
Modulated light having a predetermined polarization direction is extracted from the light emitted from 1g and 61r.

The cross dichroic prism 70 is a light combining optical system that forms a color image by combining optical images modulated for the respective color lights emitted from the polarization filters 62b, 62g, and 62r. The cross dichroic prism 70 has a substantially square shape in plan view in which four right angle prisms are bonded together, and a pair of dielectric multilayer films 71 and 72 intersecting in an X shape are formed at the interface where the right angle prisms are bonded to each other. Is formed. One first dielectric multilayer film 71 reflects the blue light LB, and the other second dielectric multilayer film 72 reflects the red light LR. The cross dichroic prism 70 reflects the blue light LB from the liquid crystal display panel 61b by the first dielectric multilayer film 71 and emits the green light LG from the liquid crystal display panel 61g to the first and second sides.
The red light L emitted from the liquid crystal display panel 61r is emitted straight through the dielectric multilayer films 71 and 72.
R is reflected by the second dielectric multilayer film 72 and emitted to the left in the traveling direction. In other words, the blue light LB and the red light LR are guided to the cross dichroic prism 70 from a direction in which the blue light LB and the red light LR are bent in the cross dichroic prism 70, and the green light LG is crossed from a direction in which the green light LG travels straight in the cross dichroic prism 70. It is guided to the dichroic prism 70.

The image light combined by the cross dichroic prism 70 in this way is projected as a color image on a screen (not shown) at an appropriate magnification through a projection optical system 80 as a magnification projection lens.

In the projector 10 described above, the blue light LB is reflected by the first dichroic mirror 41a, the blue reflection mirror 42a, and the first dielectric multilayer film 71 as illumination light or image light so as to be bent a total of three times. Further, the green light LG is reflected so as to be bent once by the second dichroic mirror 41b as illumination light or image light. The red light LR is
Reflective mirrors 42c, 42d, 42e for red as illumination light or image light, and the second dielectric multilayer film 7
2, the light is reflected so that it is bent a total of four times, and the relay lenses 45 and 46 cause the illumination structure to be inverted, that is, vertically and horizontally reversed. That is, blue light LB and green light LG
, The number of reflections is a difference of an even number, and the left and right inversion of the illumination light image by the mirror coincides (the blue light emitted from the illumination optical system 30 and incident on the color separation light guide optical system 40) Light L
The left-right relationship between the illumination light beams of B and green light LG and the left-right relationship between the illumination light beams at the time of emission from the cross dichroic prism 70 coincide with each other), and color unevenness is unlikely to occur. On the other hand, for the red light LR, the number of inversions in the left-right direction is an even number of times, and the left-right inversion of the illumination light image by the mirror and the relay lens matches (the color separation guide The left-right relationship between the illumination light beams of the blue light LB (green light LG) and the red light LR when incident on the optical optical system 40 and the left-right relationship between the illumination light beams at the time of emission from the cross dichroic prism 70 coincide with each other. Color unevenness is unlikely to occur. Here, if the light emitted from the relay lens 45 is reflected by only one mirror in order to enter the relay lens 46, the illumination light image is reversed left and right compared with the blue light LB and the green light LG. Since the number of times becomes an odd number, the illumination light flux of the blue light LB (green light LG) and the red light LR emitted from the illumination optical system 30 and incident on the color separation light guide optical system 40 is left as it is. And the left-right relationship between the illumination light beams at the time of emission from the cross dichroic prism 70 do not match. However, in the third optical path OP3 for red, red reflecting mirrors 42c and 42d are provided in order to make the light emitted from the relay lens 45 enter the relay lens 46. The number of reflections is an odd number, and relay lenses 45 and 46 are used.
In combination with the up / down / left / right reversal in FIG. That is, the number of reflections by the mirror in the red light path where the relay lens is arranged is an odd number of times than the number of mirror reflections in the light paths of other color lights where the relay lens is not arranged (in the light paths of the blue light path LB and the green light path LG). By increasing the number of times, the illumination light image of the red light LR when emitted from the cross dichroic prism 70 is inverted upside down when compared with the illumination light images of the blue light LB and the green light LG at the same point. However, there is no left-right reversal. Therefore, after the illumination light of the blue light LB, the green light LG, and the red light LR is finally combined by the cross dichroic prism 70, the relationship between the left and right directions is the left and right direction at the emission of the illumination optical system 30. The color unevenness is less likely to occur in the left-right direction of the combined image light.
In other words, according to the projector 10 of the present embodiment, the color unevenness of the projected image can be reduced with respect to the left and right direction with high importance without complicating the structure of the color separation light guide optical system 40. A high-quality image can be projected by an optical system with a simple configuration.

In the color separation light guide optical system 40, in the third optical path OP3 formed by the red reflection mirrors 42c, 42d, and 42e, the system optical axis OA that is the illumination optical axis intersects on the same plane. Thereby, the red third optical path OP3 can be incorporated in the projector in a space-saving manner. As is apparent from the figure, these red reflecting mirrors 4
The incident angles of the illumination light beams with respect to 2c, 42d, and 42e are each close to 90 °, and by reducing the variation in the incident angles, it is possible to prevent the angle-dependent dimming with respect to the incident angles, that is, the occurrence of color unevenness.

[Second Embodiment]
Hereinafter, a projector according to a second embodiment of the invention will be described. Note that the projector according to the second embodiment is obtained by partially changing the projector according to the first embodiment, and parts that are not particularly described are the same as those of the first embodiment.

FIG. 2 is a conceptual diagram illustrating the configuration of the optical system of the projector according to the second embodiment. In the projector 110 of the present embodiment, the color separation light guide optical system 140 includes red reflection mirrors 142c, 142d, and 142e that are newly arranged. In this case, the mirror 14 that crosses the optical path.
2d and 142e are disposed relatively close to the liquid crystal display panel 61r.

[Third Embodiment]
Hereinafter, a projector according to a third embodiment of the invention will be described. Note that the projector according to the third embodiment is obtained by partially changing the projector according to the first embodiment, and parts that are not particularly described are the same as those of the first embodiment.

FIG. 3 is a conceptual diagram illustrating the configuration of the optical system of the projector according to the third embodiment. In the projector 210 of the present embodiment, the color separation light guide optical system 240 includes a first reflective element 242A and a second reflective element 242B as reflective element systems. Here, the first reflecting element 242A includes a polarizing beam splitter 42f that incorporates a polarization separating film 42g, a quarter-wave plate 42h that is a phase difference plate, and a reflecting film 42i that is a mirror. The red light LR guided to the third optical path OP3 enters the liquid crystal display panel 61r via the first and second relay lenses 45 and 46, the first reflecting element 242A, the second reflecting element 242B, and the field lens 43r. Incident light is illuminated. In particular, the red light LR that has entered the first reflecting element 242A via the first relay lens 45 is reflected by the polarization separation film 42g and reflected again by the reflecting film 42i. At this time, since the ¼ wavelength plate 42h reciprocates, the polarization direction can be rotated by 90 °, and the reflective film 4
The red light LR that is the reflected light from 2i passes through the polarization separation film 42g and enters the second relay lens 46. The second reflecting element 242B is the same as the mirror 42e shown in FIG. In this case as well, as in the case of the red reflecting mirrors 42c, 42d, and 42e of the first embodiment, a total of 3 in the reflective element system portion, that is, the polarization separation film 42g, the reflective film 42, and the reflective element 242B. Since the illumination light image of the red light LR is upside down when compared with the illumination light images of the blue light LB and the green light LG, the left and right inversion does not occur. Therefore, the directions in which the illumination lights of the blue light LB, the green light LG, and the red light LR are finally combined coincide with each other in the left-right direction, and color unevenness is less likely to occur in the left-right direction.

When the color separation light guide optical system 240 is provided, the polarization direction can be switched by the first reflecting element 242A. Therefore, for example, a ½ wavelength plate is disposed in the third optical path OP3 to switch the polarization direction. In such a case, such a half-wave plate becomes unnecessary. The third
When it is not necessary to switch the polarization direction in the optical path OP3, a polarization plate can be restored by providing a half-wave plate on the optical path.

[Fourth Embodiment]
Hereinafter, a projector according to a fourth embodiment of the invention will be described. Note that the projector according to the fourth embodiment is obtained by partially changing the projector according to the third embodiment, and parts that are not particularly described are the same as those of the third embodiment.

FIG. 4 is a conceptual diagram illustrating the configuration of the optical system of the projector according to the fourth embodiment. In the projector 310 of the present embodiment, the color separation light guide optical system 340 includes a first reflective element 342A and a second reflective element 342B as reflective element systems. Here, the first reflective element 342A is the same as the second reflective element 342B in FIG.
B is the same as the first reflective element 242A of FIG. That is, the first reflective element 34
When the order of 2A and the second reflective element 342B is changed, the color separation light guide optical system 2 of the third embodiment is used.
It will be the same as 40. In this case, the second reflecting element 342B that intersects the optical paths is disposed relatively close to the liquid crystal display panel 61r.

Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and can be implemented in various modes without departing from the gist thereof. Such modifications are also possible.

That is, in the above embodiment, the case where the blue light LB, the green light LG, and the red light LR are guided to the first optical path OP1, the second optical path OP2, and the third optical path OP3, respectively, has been described.
These combinations can be freely changed by changing the design of the first and second dichroic mirrors 41a and 41b, which are color separation optical systems. For example, blue light LB and green light L
G can be guided to the long third optical path OP3.

In the projector 10 of the above embodiment, the lamp body 2 of the light source lamp unit 20 is also used.
A high-pressure mercury lamp or the like is used as 1, but various lamps capable of obtaining substantially white illumination light and solid light-emitting elements such as LEDs can be used.

Further, in the projector 10 of the above-described embodiment, the illumination optical system 30 is replaced with the multi-lenses 31 and 3.
2, the polarization conversion device 34 and the superimposing lens 35, but the multi-lenses 31 and 32 can be omitted or replaced with a rod integrator.

Further, the present invention can be applied to a front projection type projector that projects from the side that observes the projected image, and a rear projection type projector that projects from the side opposite to the side that observes the projected image.

It is a top view for demonstrating the optical system of the projector which concerns on 1st Embodiment. It is a top view for demonstrating the optical system of the projector which concerns on 2nd Embodiment. It is a top view for demonstrating the optical system of the projector which concerns on 3rd Embodiment. It is a top view for demonstrating the optical system of the projector which concerns on 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Projector, 20 ... Light source lamp unit, 21 ... Lamp main body, 22 ... Secondary mirror, 23 ... Primary mirror, 24 ... Concave lens, 31, 32 ... Multi lens, 34 ... Polarization converter, 40 ... Color separation light guide optical system 41a ... first dichroic mirror, 41b ... second dichroic mirror, 42 ... reflection film, 42c, 42d, 42e ... reflection mirror for red, 42f ... polarization beam splitter, 42i ... reflection film, 45,46 ... relay lens, 61b 61g, 61r ... liquid crystal display panel, 62b, 62g, 62r ... polarizing filter, 71 ... first dielectric multilayer film, 72 ... second dielectric multilayer film, LB ... blue light, LG,
... Green light, LR ... Red light, OA ... System optical axis, OP1-OP3 ... First to third optical paths

Claims (7)

An illumination device that emits illumination light;
Illumination light in a color separation optical system that separates illumination light from the illumination device into three color lights, and one optical path for a predetermined color that is longer than the optical paths for the other colors among the optical paths of the three color lights A color separation light-guiding optical system including a relay optical system that transmits an inverted image and a reflection element system that horizontally inverts an illumination light image by bending the optical path for the predetermined color;
A liquid crystal light valve for each color light that modulates the light guided to the optical path for each color light separated by the color separation light guide optical system according to image information;
A light combining optical system for combining image light of each color modulated by the liquid crystal light valve;
A projection optical system for projecting image light that has passed through the light combining optical system;
A projector comprising: The number of reflections in the color separation light guiding optical system and the light combining optical system regarding the optical path for the predetermined color is
The projector according to claim 1, wherein the number of times of reflection by the color separation light guide optical system and the light combining optical system regarding the optical path for the other color is an odd number of times. The color separation light guide optical system includes two dichroic mirrors arranged along an optical path as the color separation optical system,
One of the optical paths for the other colors is bent by the optically upstream dichroic mirror, bent again by an additional mirror for optical path bending, and the light combining from the direction where it is bent in the light combining optical system. Led to the optical system,
The other of the optical paths for the other colors is bent by the optically downstream dichroic mirror and guided to the light combining optical system from a direction that goes straight in the light combining optical system,
The optical path for the predetermined color travels straight through the two dichroic mirrors, and is guided to the light combining optical system from a direction in which the light path is bent in the light combining optical system via the relay optical system and the reflecting element system. 2. The projector according to 2. The projector according to any one of claims 1 to 3, wherein the reflective element system includes three reflective elements. The projector according to any one of claims 1 to 4, wherein the reflection element system includes any one of a reflection element including only a mirror, and a reflection element including a polarization beam splitter, a phase difference plate, and a mirror. The projector according to any one of claims 1 to 5, wherein illumination optical axes of the optical paths for the three colors are arranged on the same plane. The projector according to claim 6, wherein illumination optical axes of the optical path for the predetermined color intersect on the same plane.

Images