JP2000206450A - Projection type display device and light selecting prism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the difference of the sizes of the projecting screens of respective colors caused by the transverse chromatic aberration of a projecting optical system. SOLUTION: This device is provided with a lens element or a prism element for adjusting at least the size of the projecting screen along a specified direction by color light passing through at least one optical path among three optical paths from the light exit surfaces of three electric optical devices to light incident surfaces, corresponding to a color light synthesizing optical system so that the size becomes substantially equal to the size of the projecting screen at least along the specified direction by the color light passing through another optical paths on at least one optical path from among the three optical paths.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a projection display device and a light selection prism.

[0002]

2. Description of the Related Art In many cases, a projection display device for projecting and displaying a color image uses three electro-optical devices and a light selection prism. FIG. 6 is a conceptual diagram showing a main part of a conventional projection display device. This projection display device includes three liquid crystal light valves (liquid crystal panels) 42, 44, and 46 as electro-optical devices, a cross dichroic prism 48 as a light selection prism, and a projection optical system 5.
0. Cross dichroic prism 48
, A red reflecting film 48R and a blue reflecting film 48B are formed in a substantially X-shape. The cross dichroic prism 48 combines the three color lights of red, green, and blue modulated by the three liquid crystal light valves 42, 44, and 46 and emits the light toward the projection optical system 50. The projection optical system 50 forms the combined three color lights on a projection screen 52.
Thereby, a color image is projected on the projection screen 52.

[0003]

However, the projection optical system 5
0 usually has chromatic aberration of magnification, and thus often has a problem that the size of the projection screen differs for each color light.

The present invention has been made to solve the above-mentioned problems in the prior art, and has an object to provide a technique for reducing a difference in size of a projection screen of each color caused by chromatic aberration of magnification of a projection optical system. Aim.

[0005]

In order to solve at least a part of the above-mentioned problems, a projection display apparatus according to the present invention comprises: an illumination optical system for emitting illumination light; A color light separation optical system for separating light into three color lights, and three electro-optical devices into which the respective color lights separated by the color light separation optical system are separately incident, wherein each color light is converted into each color in accordance with an image signal of each color. And three light-selecting surfaces formed so as to intersect substantially in an X-shape. The light is emitted from the three electro-optical devices. A color light combining optical system for combining the three color lights obtained, and a projection optical system for projecting the light combined by the color light combining optical system, and the color light combining optical system from the exit surfaces of the three electro-optical devices. Of the three optical paths to the corresponding entrance surface of At least on one optical path, the size along the at least a predetermined direction of the projection screen by the color light passing on the at least one optical path is set in the predetermined direction of the projection screen by the color light passing on the other optical path. And a lens or prism element that adjusts to approximately equal the size along.

According to the above configuration, it is possible to reduce the problem that the screen sizes of the respective colors formed by the three color lights generated by the chromatic aberration of magnification of the projection optical system are different.

In the above-mentioned projection type display device, it is preferable that the lens element is formed by making the incident surface of the color light combining optical system a curved surface. Further, it is preferable that the prism element is configured by making the incident surface of the color combining optical system into a prism shape.

With this configuration, it is possible to reduce the difference in the size of the projection screen of each color caused by the chromatic aberration of magnification of the projection optical system with the same configuration as the related art without adding a new optical element.

The lens element does not have a refracting function in a plane including a generating line perpendicular to the predetermined direction, and has a refracting function in a plane perpendicular to the generating line. Good.

With this configuration, it is possible to reduce the difference in the size of the projection screen along the direction perpendicular to the generatrix among the differences in the size of the projection screen of each color caused by the chromatic aberration of magnification of the projection optical system.

The light-selecting prism of the present invention is a light-selecting prism that combines and emits three incident color lights, and includes two light-selecting elements formed so as to intersect substantially in an X-shape. And three incident surfaces on which one color light is incident for each color light, wherein at least one of the three incident surfaces is a curved surface or a prism-shaped surface.

When the light selection prism of the present invention is used in a projection display device, the difference in the size of the projection screen of each color caused by the chromatic aberration of magnification of the projection optical system can be reduced, similarly to the projection display device. .

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic structural view of a main part of a projection type display device of the present invention as viewed in plan. The projection display device includes an illumination optical system 100, dichroic mirrors 210 and 212, and reflection mirrors 220, 222 and 224.
, The incident side lens 230, the relay lens 232,
Field lenses 240, 242, 244 and three liquid crystal light valves (liquid crystal panels) 250, 252, 2
54, a cross dichroic prism 260, and a projection optical system 270.

The illumination optical system 100 includes a light source 110 for emitting a substantially parallel light beam, a first lens array 120,
A second lens array 130, a polarization conversion element 140,
It includes a reflection mirror 150 and a superimposing lens 160. The illumination optical system 100 is an integrator optical system for almost uniformly illuminating the three liquid crystal light valves 250, 252, and 254, which are illumination regions.

The light source 110 includes a light source lamp 112 as a radiation light source for emitting a radial light beam, and a light source lamp 112.
And a concave mirror 114 that emits the radiated light emitted from the optical disk as a substantially parallel light beam. As the light source lamp 112, a high-pressure discharge lamp such as a metal halide lamp or a high-pressure mercury lamp is usually used. As the concave mirror 114, a parabolic mirror is preferably used. Note that, instead of a parabolic mirror, an elliptical mirror, a spherical mirror, or the like can be used.

The first lens array 120 includes a plurality of first small lenses 122. The second lens array 130 includes a plurality of second small lenses 132 corresponding to the plurality of first small lenses 122, respectively.
The substantially parallel light beam emitted from the light source 110 is split into a plurality of partial light beams by the first and second lens arrays 120 and 130 and enters the polarization conversion element 140.
The polarization conversion element 140 has a function of converting non-polarized light into predetermined linearly polarized light, for example, s-polarized light or p-polarized light, and emitting the same. Therefore, the plurality of partial light beams that have entered the polarization conversion element 140 are converted into predetermined linearly polarized light beams and emitted. The plurality of partial light beams emitted from the polarization conversion element 140 are reflected by the reflection mirror 150 and enter the superimposing lens 160. Superposition lens 160
Of the liquid crystal light valve 25, which is an illumination area,
0, 252 and 254 are almost superimposed. As a result, the liquid crystal light valves 250, 252, and 254 are almost uniformly illuminated.

Two dichroic mirrors 210 and 21
Reference numeral 2 has a function as a color light separation optical system that separates light emitted from the illumination optical system 100 into three color lights of red (R), green (G), and blue (B). The first dichroic mirror 210 transmits the red light component of the light emitted from the illumination optical system 100 and reflects the blue light component and the green light component.

The red light transmitted through the first dichroic mirror 210 is reflected by the reflection mirror 220, passes through the field lens 240, and passes through the liquid crystal light valve 25 for red light.
Reaches 0. The field lens 240 has a function of condensing each passing partial light beam so as to be a light beam parallel to the principal ray (center axis) of each partial light beam. Field lens 2 provided in front of another liquid crystal light valve
42 and 244 are the same.

Of the blue light and the green light reflected by the first dichroic mirror 210, the green light is reflected by the second dichroic mirror 212, passes through the field lens 242, and reaches the liquid crystal light valve 252 for green light. . On the other hand, the blue light passes through the second dichroic mirror 212 and passes through the incident side lens 230 and the relay lens system including the relay lens 232 and the reflection mirrors 222 and 224. The blue light that has passed through the relay lens system further passes through a field lens 244 and reaches a liquid crystal light valve 254 for blue light.

The reason why the relay lens system is used for blue light is to prevent a decrease in light use efficiency generated due to the optical path length of blue light being longer than the optical path lengths of other color lights. That's why. That is, it is for transmitting the blue light incident on the incident side lens 230 to the exit side lens (field lens) 244 as it is.

Three liquid crystal light valves 250, 252,
Reference numeral 254 has a function as an electro-optical device that converts the light of each color incident on the light into light for forming an image in accordance with a given image signal and emits the light. Since a polarizing plate is usually provided on the light incident surface of the liquid crystal light valves 250, 252, and 254, the illumination optical system 1
The polarization direction of the linearly polarized light emitted from 00 is set to a polarization direction substantially equal to the transmission axis of these polarizing plates. In this way, the illumination light emitted from the illumination optical system 100 can be used efficiently. The cross dichroic prism 260 includes three liquid crystal light valves 25.
It has a function as a color light combining optical system that combines three color lights emitted from 0, 252, and 254. In the cross dichroic prism 260, a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in an approximately X-shape at the interface between the four right-angle prisms. The three colored lights are combined by these dielectric multilayer films to form combined light for projecting a color image. The combined light generated by the cross dichroic prism 260 is emitted toward the projection optical system 270. Projection optical system 270
Projects this combined light onto the projection screen 300,
It has a function as a projection optical system for displaying a color image.

The projection display device of the present invention is characterized by the shape of the cross dichroic prism 260. FIG. 2 is an explanatory diagram showing the cross dichroic prism 260 in the projection display device of the present invention in comparison with the cross dichroic prism 48 in the conventional projection display device. FIG. 2A is a schematic plan view showing the cross dichroic prism 260 of the projection display device of the present invention. FIG. 2A is a schematic diagram of a screen displayed by the combined light emitted from the cross dichroic prism 260. FIG. 2B-1 shows a cross dichroic prism 4 of a conventional projection display device (FIG. 6).
8 is a schematic plan view showing FIG. FIG. 2B-2 is a schematic diagram of a screen displayed by the combined light emitted from the cross dichroic prism 48.

As shown in FIG. 2 (B-1), three incident surfaces 48I of a conventional cross dichroic prism 48 are formed.
R, 48IG, and 48IB are each substantially planar.

Since the projection optical system 270 (FIG. 1) usually has chromatic aberration of magnification, the magnification of the projection screen changes according to the color of light incident on the projection optical system, that is, the wavelength of the light. I do. Therefore, the conventional projection display device (FIG. 2 (B-
On the screen 300 of 1)), FIG.
As shown in 2), the sizes of the screens IR, IG, and IB formed by the R, G, and B color lights may be different from each other. FIG. 2B-2 shows a case where the screen becomes smaller in order from light having a longer wavelength to light having a shorter wavelength, that is, a red screen IR> a green screen IG> a blue screen IB.
The case where it becomes is shown.

On the other hand, the projection type display device of the present invention (see FIG.
-1)), the cross dichroic prism 2
The red light incident surface 260IR of 60 is concave, and the blue light incident surface 260IB is convex. The concave surface of the red light incident surface 260IR has a function of reducing the size of the red screen IR such that the size of the red screen IR is substantially equal to the green screen IG. Further, the convex surface of the blue light incident surface 260IB has a function of enlarging the size of the blue screen IB so as to be substantially equal to the size of the green screen IB. As a result, in the projection display device of the present invention, as shown in FIG. 2A-2, the sizes of the screens IR, IG, and IB of each color can be made substantially equal. That is, in the projection display apparatus of the present invention, the difference in the size of the projection screen of each color caused by the chromatic aberration of magnification of the projection optical system can be reduced.

The concave surface of the red light incident surface 260IR and the convex surface of the blue light incident surface 260IB can be formed by polishing a flat incident surface to be a concave surface or a convex surface. Also, a concave surface of the red light incident surface 260IR and a convex surface of the blue light incident surface 260IB can be realized by attaching a concave lens or a convex lens to the incident surface. Further, it may be formed of a resin film which is cured by irradiating light such as ultraviolet rays or applying heat. The concave surface and the convex surface may be not only spherical but also aspheric.

In the embodiment shown in FIG. 1, the red light incident surface 260I
The case where the R and blue light incident surfaces 260IB are curved surfaces is described as an example. However, in addition to these, it is also possible to make the green incident surface 260G a convex surface or a concave surface (curved surface), and make all the incident surfaces curved. Further, any one of the incident surfaces may be a curved surface.

FIG. 3A-1 is a schematic plan view showing another embodiment of the cross dichroic prism 260. FIG.
In the cross dichroic prism 260A, only the red light incident surface 260AIR is concave. In this case, as shown in FIG. 3A-2, the size of the red screen IR is set to be an intermediate size between the screens IG and IB of other colors. As a result, the size difference between the red screen IR and the green screen IG and the size difference between the red screen IR and the blue screen IB can be reduced. Accordingly, it is possible to reduce a difference in screen size between colors due to chromatic aberration of magnification of the projection optical system 270.

In this case, it is not always necessary to set the size of the red screen IR to an intermediate size between the screens IG and IB of other colors. For example, the size of the red screen IR may be made substantially equal to the green screen IG or the blue-green screen IB. In other words, it is only necessary that the difference in size between at least two screens among the screens of each color is set to be smaller than in the related art.

As can be seen from the above, in the present invention, "the screen sizes are substantially equal" means that not only the sizes between the screens are equal, but also the difference in the size between the screens is smaller than in the prior art. The meaning is also included.

FIG. 3B-1 is a schematic plan view showing still another embodiment of the cross dichroic prism 260. This cross dichroic prism 260B
Only the blue light incident surface 260BIB is a convex curved surface. Also in this case, as shown in FIG. 3B-2, by setting the size of the blue screen IB to a size intermediate between the screens IR and IG of other colors, the size of the screen of each color The size difference can be reduced. Thus, the influence of the chromatic aberration of magnification of the projection optical system 270 on the screen size can be reduced. In this case as well, the size of the blue screen IB is not necessarily changed to the screens IR and I of other colors.
There is no need to set the size in the middle of G. For example, the size of the blue screen IB may be made substantially equal to the size of the green screen or the red screen IR. That is,
It is sufficient that the difference in size between at least two screens among the screens of each color is set to be smaller than in the related art.

FIG. 4A is a schematic plan view showing still another embodiment of the cross dichroic prism 260. This cross dichroic prism 260C is
An example is shown in which the red light incident surface 260CIR is a cylindrical concave surface (cylindrical concave surface) having a generatrix perpendicular to the paper surface, and the blue light incident surface 260CIB is a cylindrical convex surface (cylindrical convex surface) having a generatrix perpendicular to the paper surface. ing. Also in this case, as shown in FIG. 4A-2, the screens IR, IG, and IB of each color can be made substantially equal in size in the screen horizontal direction. That is, among the differences in the size of the projection screen of each color caused by the chromatic aberration of magnification of the projection optical system 270, the direction perpendicular to the generatrix (screen horizontal direction)
, The difference in the size of the projection screen along the distance can be reduced.

In the projection display apparatus, when tilt projection is performed in the vertical direction, the size of the screen of each color in the vertical direction may change depending on the position of the tilt projection. In such a case, it may be sufficient to adjust only the horizontal size of the screen of each color. The cross dichroic prism 260C can be effectively used in such a case.

When adjusting only the size of the screen in the vertical direction, a cross dichroic prism having a lens element set so that the generatrix of the cylindrical curved surface is parallel to the horizontal direction may be used.

It should be noted that not only the red light incident surface 260 CIR and the blue light incident surface 260 CIB but also the green light incident surface 260
It is also possible to make the CIG a cylindrical curved surface. Further, it is also possible to make only one of the incident surfaces a cylindrical curved surface.

In the example of FIG. 4, the case where the incident surface is a cylindrical curved surface is described as an example, but the present invention is not limited to this. The incident surface may be an elliptic cylindrical curved surface. That is, any curved surface may be used as long as it does not have a refraction effect in a plane including the curved generatrix and has a refraction action in a plane perpendicular to the curved generatrix. Here, "having no refraction in a plane including a curved surface generating line" means that when an optical path of light passing through an incident surface having a curved surface is projected on a plane including a curved surface generating line, It means that the light path of the light does not seem to be refracted. Further, "having a refraction effect in a plane perpendicular to the curved surface generating line" means that when the optical path of light passing through the curved incident surface is projected on a plane perpendicular to the curved surface generating line, the projected light Means that the optical path of the light beam appears to be refracted.

FIG. 5 shows a cross dichroic prism 2
FIG. 40 is a schematic plan view showing still another embodiment of the present invention. The cross dichroic prisms 260, 260 described above
In A, 260B and 260C, the concave or convex surface of the entrance surface of the cross dichroic prism is constituted by a curved lens shape. Since these lens shapes are often very thin having a large radius of curvature, this curved surface may be approximated by a plane to form a prism shape.

The cross dichroic prism 26 of this embodiment
0D is the cross dichroic prism 2 shown in FIG.
The red light incident surface 260CIR of 60C is approximated by a plane,
The red light incident surface 260DIR is formed of a prism-shaped concave surface (a prismatic concave surface) having a ridge line perpendicular to the paper surface. Further, the blue light incident surface 260CIB of the cross dichroic prism 260C is approximated by a plane to form a blue light incident surface 260DIB constituted by a prism-shaped convex surface (a prismatic convex surface) having a generatrix perpendicular to the paper surface. Similar to the lens shape described above, these prism shapes are polished so that the incident surface becomes a concave or convex surface of the prism shape, or a plano-concave prism or a plano-convex prism is attached to the incident surface. It can be realized by doing. Further, it may be formed of a resin film which is cured by irradiating light such as ultraviolet rays or applying heat.

Also in this case, similarly to the dichroic prism 260C, that is, as shown in FIG. 4A-2, the screens IR, IG, and IB of each color have substantially the same size in the horizontal direction of the screen. can do. That is, the difference in the size of the projection screen along the direction perpendicular to the generatrix (the horizontal direction of the screen) among the size differences of the projection screens of the respective colors caused by the chromatic aberration of magnification of the projection optical system 270 can be reduced.

It is to be noted that not only the red light incident surface 260DIR and the blue light incident surface 260DIB but also the green light incident surface 260D
It is also possible for the IG to have a prism shape. It is also possible to make only one of the incident surfaces into a prism shape.

It should be noted that the present invention is not limited to the above Examples and Embodiments, but can be implemented in various modes without departing from the gist thereof.
For example, the following modifications are possible.

(1) In the above embodiment, an example in which the size of the screen of each color generated by the chromatic aberration of magnification of the projection optical system is as follows: red screen IR> green screen IG> blue screen IB. But not limited to this. For example, there may be a case where red screen IR <green screen IG <blue screen IB. Even in such a case, at least one of the incident lights of the cross dichroic prism is set such that the size of the screen in at least one direction among the sizes of the projection screen of at least one color is substantially equal to the size of the screen of another color. The surface may be a curved surface or a prism shape. In addition, as a method of forming a curved surface or a prism shape, in addition to directly polishing the incident surface, a resin that is cured by attaching a lens or a prism to the light incident surface, irradiating light such as ultraviolet light, or applying heat. A thin film may be provided on the light incident surface.

(2) In the above embodiment, the case where the incidence surface of the cross dichroic prism has a curved surface or a prism shape is described as an example, but the present invention is not limited to this. Between the exit surface of the liquid crystal light valve and the entrance surface of the cross dichroic prism, a lens element or a prism element for correcting a difference in the size of each color image due to chromatic aberration of magnification of the projection optical system may be arranged. .
Even in this case, it is possible to reduce the difference in the screen size of each color caused by the chromatic aberration of magnification of the projection optical system.

(3) In the above embodiment, the liquid crystal light valve (liquid crystal panel) is used as the electro-optical device of the projection display device, but the present invention is not limited to this. For example, a micromirror device that performs light modulation by controlling reflected light at the angle of the micromirror may be used. That is, various devices that emit light for forming an image in accordance with an image signal can be used as the electro-optical device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part of a projection display device of the present invention as viewed in plan.

FIG. 2 is an explanatory diagram showing a cross dichroic prism 260 in the projection display device of the present invention in comparison with the cross dichroic prism 48 in the conventional projection display device.

FIG. 3 is an explanatory view showing another embodiment of the cross dichroic prism 260.

FIG. 4 is an explanatory view showing still another embodiment of the cross dichroic prism 260.

FIG. 5 is an explanatory view showing still another embodiment of the cross dichroic prism 260.

FIG. 6 is a conceptual diagram showing a main part of a conventional projection display device.

[Explanation of symbols]

 42, 44, 46 liquid crystal light valve 48 cross dichroic prism 48B blue reflective film 48R red reflective film 48IR, 48IG, 48IB incident surface 50 projection optical system 52 projection screen 100 illumination optical system 110 light source 112 ... light source lamp 114 ... concave mirror 120 ... first lens array 122 ... first small lens 130 ... second lens array 132 ... second small lens 140 ... polarization conversion element 150 ... reflection mirror 160 ... superimposing lens 210 ... first 1 dichroic mirror 212 ... second dichroic mirror 220 ... reflecting mirror 222,224 ... reflecting mirror 230 ... incident side lens 232 ... relay lens 240,242 ... field lens 244 ... field lens (exit side lens) 250,252,254 … Liquid crystal light Lube 260: Cross dichroic prism 260IR: Red light incident surface 260IG: Green light incident surface 260IB: Blue light incident surface 260A: Cross dichroic prism 260AIR: Red light incident surface 260B: Cross dichroic prism 260BIB: Blue light incident surface 260C: Cross dichroic Prism 260CIB Blue light incident surface 260CIG Green light incident surface 260CIR Red light incident surface 260D Cross dichroic prism 260DIB Blue light incident surface 260DIG Green light incident surface 260DIR Red light incident surface 270 Projection optical system 300 Projection screen

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference)

Claims (7)

[Claims] 1. A projection display device for projecting and displaying an image, comprising: an illumination optical system that emits illumination light; a color light separation optical system that separates the illumination light into three color lights; An electro-optical device in which each color light separated by an optical system is separately incident, wherein each of the color lights is converted into light for forming an image of each color in accordance with an image signal of each color and emitted. Two electro-optical devices, a color light combining optical system having two light selection surfaces formed so as to intersect substantially in an X shape, and combining three color lights emitted from the three electro-optical devices, A projection optical system for projecting the light combined by the color light combining optical system, and at least one of three optical paths from an exit surface of the three electro-optical devices to a corresponding incident surface of the color light combining optical system. On the optical path, on the at least one optical path A lens element that adjusts the size of at least a predetermined direction of the projection screen by the passing color light along the predetermined direction of the projection screen by the color light passing on another optical path, Projection display device. 2. The projection display device according to claim 1, wherein the lens element is configured by making an incident surface of the color light combining optical system a curved surface. 3. The projection type display device according to claim 1, wherein the lens element has no refraction in a plane including a generating line perpendicular to the predetermined direction, and the lens element has A projection display device that has a refractive effect in a vertical plane. 4. A projection display device for projecting and displaying an image, comprising: an illumination optical system for emitting illumination light; a color light separation optical system for separating the illumination light into three color lights; An electro-optical device in which each color light separated by an optical system is separately incident, wherein each of the color lights is converted into light for forming an image of each color in accordance with an image signal of each color and emitted. Two electro-optical devices, a color light combining optical system having two light selection surfaces formed so as to intersect substantially in an X shape, and combining three color lights emitted from the three electro-optical devices, A projection optical system for projecting the light combined by the color light combining optical system, and at least one of three optical paths from an exit surface of the three electro-optical devices to a corresponding incident surface of the color light combining optical system. On the optical path, on the at least one optical path A prism element that adjusts the size of at least a predetermined direction of the projection screen by the passing color light to be substantially equal to the size of the projection screen by the color light passing on another optical path along the predetermined direction, Projection display device. 5. The projection display device according to claim 4, wherein the prism element is configured by making an incident surface of the color light combining optical system into a prism shape. 6. A light selection prism for combining and emitting three incident color lights, wherein two light selection elements formed so as to intersect substantially in an X-shape; And a light-selecting prism, wherein at least one of the three light-entering surfaces is a curved surface. 7. A light selection prism that combines and emits three incident color lights, wherein the two light selection elements are formed so as to intersect substantially in an X-shape; A light-selecting prism, comprising: a light-receiving prism; and three light-entering surfaces, wherein at least one of the three light-entering surfaces is a prism-shaped surface.