JP2000098493A - Illumination device and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen the illumination unevenness of an illumination device and to reduce its size. SOLUTION: The parallel luminous fluxes emitted from a light source 11 are made incident on an illumination plate 12. This illumination plate 12 is formed by lining up a plurality of tile-like wedge plates 12a longitudinally and transversely on a plane orthogonal with the progression direction of the light. The external shape when the wedge plates 12a are viewed from the side of a light valve 13 nearly coincides with the shape of the portion to be illuminated of the light valve 13. The plural wedge plates 12a have different vertex angles. The vertex angle of the wedge plates 12a existing around the circumference of the illumination plate 12 is larger than the vertex angle existing at the center. The parallel luminous fluxes emitted from the light source 1 are split to the plural small luminous fluxes while the parallel state of the luminous fluxes is maintained when passing each of the plural wedge plates 12a. These plural small luminous fluxes are so introduced as to illuminate the same portion to be illuminated of the light valve 13 in superposition, by which the luminance unevenness of the light source 11 is averaged and the uniform illuminance may be obtained on the light valve 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device and a projection device, and more particularly to a method of illuminating a light valve with a light beam emitted from the illuminating device and separated by polarization, and transmitted through the light valve or reflected by the light valve. The present invention relates to a projection device for detecting and projecting light modulated in the above manner.

[0002]

2. Description of the Related Art Illumination light emitted from a light source and polarized and separated is guided to a light valve for illumination, and illumination light modulated when transmitted through the light valve or reflected by the light valve is detected and projected. 2. Description of the Related Art Projection devices that project onto a screen with a lens are known. In this projection device, as an illumination device for illuminating a liquid crystal light valve, FIG.
Are well known.

In FIG. 8, a light source 101 is a lamp 101
a, and a concave mirror 101b such as a parabolic mirror, and the illumination light emitted from the light source 101 is a substantially parallel light flux. The illumination light emitted from the light source 101 is incident on a first lens plate 102 configured by arranging a plurality of first small lenses 102a on one plane, and the first small lenses 102a
Are divided into a plurality of light beams defined by the respective outer shapes. At each focal position of the first small lens 102a,
A plurality of second small lenses 103a are arranged facing each of the first small lenses 102a. These second small lenses 103a are arranged on one plane similarly to the first lens plate 102 to form the second lens plate 103.

With the above-described configuration, the first small lens 102
Illumination light incident on each of the second small lenses 103a
A bright spot is formed on a. Light emitted from each bright spot of the second small lens 103a illuminates the light valve 105 via the condenser lens 104. That is, the illumination light emitted from the light source 101 is divided by the number of the first small lenses 102a and the second small lenses 103a, and then illuminated in a superimposed manner on the light valve 105, thereby uniformly illuminating the light valve 105. Can be illuminated.

The above-described illumination device is incorporated in a projection device, and illumination light incident on the light valve 105 is modulated according to an image signal input to the light valve 105 when passing through the light valve 105. Light valve 10
The modulated light that has passed through 5 is projected onto a screen by a projection lens (not shown) disposed behind light valve 105.

The above described is the simplest configuration using one light valve. On the other hand, in a color projection apparatus using three light valves for R light, G light and B light, light passing through the condenser lens 104 in FIG. 8 passes through a color separation optical system (not shown). It is color-separated into R light, G light and B light. The R light, the G light, and the B light are respectively incident on the light valves for the respective color lights, are modulated according to the image signals input to the light valves for the respective color lights, and are emitted from the light valves. The emitted light is color-combined by a color-combining optical system, and is projected through a projection lens.

[0007]

In the above-described illumination device, the illumination light emitted from the light source 101 is divided and illuminated in a superimposed manner on the light valve 105. A first lens plate 102 and a second lens plate 103 provided are used. For this reason, the arrangement space from the light source 101 to the second lens plate 103 is large. For this reason, the size of the lighting device has been increased, which has prevented the projection device from being downsized.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lighting device which can be reduced in size and has excellent uniformity of illumination light distribution, and a projection device using the lighting device.

[0009]

Means for Solving the Problems (1) Referring to FIG. 4 showing an embodiment, the invention according to claim 1 is a light source 11 for emitting a substantially parallel light beam for illumination; A divided light guide for dividing a plurality of small luminous fluxes into a plurality of small luminous fluxes while maintaining a substantially parallel luminous flux state of the use luminous flux and superimposing and illuminating substantially the same illumination area of the illuminated object 13 with the plurality of small luminous fluxes. By having the means 12, the above-mentioned object is achieved.
The following invention will be described in association with FIG. 7 showing one embodiment. (2) The invention according to claim 2 separates the substantially parallel illumination light beam emitted from the light source 11 into light beams of a plurality of colors, and a plurality of light valves 57R provided corresponding to the light beams of the plurality of colors. , 57G, and 57B, respectively, polarization-separated light beams of a plurality of colors are guided, and a plurality of light valves 57R, 57B are provided.
The present invention is applied to a projection apparatus that analyzes and color-combines light modulated by G and 57B and projects the combined light. Then, the light beam for illumination is divided into a plurality of small light beams while maintaining a substantially parallel light beam state, and the plurality of small light beams are illuminated by overlapping each of the plurality of light valves 57R, 57G, and 57B with the plurality of small light beams. Is provided. (3) According to the invention described in claim 3, the cross-sectional shape of the small light beam divided by the divided light guide means 12 on a plane orthogonal to the light beam traveling direction is a plurality of light valves 57R, 57G, 5G.
7B is substantially the same as the outer shape of the image forming portion 7B. The following invention will be described in association with FIG. 6 showing an embodiment. (4) According to the invention described in claim 4, the sectional shape of the small light beam divided by the divided light guide means 2 in a plane orthogonal to the light beam traveling direction is a plurality of light valves 40R, 40G, 40.
B is a proportionally reduced shape of the outer shape of the image forming portion. (5) The invention according to claim 5 is disposed between the color separation optical systems 34 and 37 for color-separating a plurality of small luminous fluxes guided by the split light guide means 2 and the split light guide means 2. And a plurality of converging optical systems 4R, 4G, and 4B respectively disposed between the color separation optical systems 34 and 37 and the plurality of light valves 40R, 40G, and 40B. .

In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used for easy understanding of the present invention. However, the present invention is not limited to this.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment FIG. 1 is a diagram showing a schematic configuration of an illumination device according to a first embodiment of the present invention and a projection device using the illumination device. .

A concave mirror 1 having a lamp 1a and a parabolic reflection surface
b, the illumination light of substantially parallel light flux is emitted and enters the illumination plate 2. In the present embodiment, the shape of the luminous flux of the illumination light emitted from the light source 1 in a cross section orthogonal to the traveling direction of the light is substantially a perfect circle.

In FIG. 2 showing a schematic shape of the lighting plate 2,
Since the cross-sectional shape of the illumination light beam emitted from the light source 1 has a substantially perfect circular shape as described above, the outer shape of the illumination plate 2 is a square inscribed in the circle of the cross-section of the illumination light beam in consideration of the illumination efficiency. It has a shape. The light source illuminating plate 2 described above is configured by arranging a total of 25 wedge plates 2a of 5 vertically and 5 horizontally in a tile shape. The external shapes of the wedge plates 2a when viewed from the optical axis direction are all squares of the same size. This is because the shape of the illuminated portion of the light valve 5, that is, the image forming portion of the light valve 5 is square in the present embodiment, and the outer shape of each wedge plate 2a is This is because it is necessary to make the shape of the portion proportionally reduced. The reason will be described later.

Each of the 25 wedge plates 2a has its incident side (the back side in FIG. 2) parallel to a plane perpendicular to the optical axis io.
In addition, the incident surfaces of the respective wedge plates 2a are arranged so as to be aligned on one plane orthogonal to the optical axis io. That is, the incident side of the illumination plate 2 is a single plane parallel to a plane orthogonal to the optical axis io.

On the other hand, on the emission side (the front side in FIG. 2), each wedge plate 2a has an inclination corresponding to the disposition position of the wedge plate 2a. Describing this inclination, assuming that a normal vector is set from the center of each surface of the plurality of wedge plates 2a,
The direction is determined so that the extension of the normal vector intersects the optical axis io. Then, the wedge plate 2a is moved so that the incident light passing through the center of the wedge plate 2a reaches the center of the illuminated portion of the light valve 5.
Determine the slope of each. At this time, the thickness and the refractive index of each wedge plate 2a, the positional relationship between the illumination plate 2, the concave lens 3, the convex lens 4, and the light valve 5, the focal length, and the like are considered. On the other hand, a wedge plate 2a (indicated by reference numeral C in FIG. 2) disposed at the center of the illumination plate 2 is a parallel flat plate having an entrance surface and an exit surface having a surface perpendicular to the optical axis io. It has become. For the sake of simplicity, the parallel flat plate provided at the center of the illumination plate 2 is also referred to as a wedge plate. The optical axis i0 passes through a substantially central portion O of the wedge plate 2a provided at the central portion of the illumination plate 2.

Here, how to determine the inclination of the wedge plate 2a will be described more specifically with reference to FIG. In FIG. 4, h is a distance (height) from the optical axis io to the center point of the wedge plate 2a. L is an air-equivalent distance between the light valve and a perpendicular drawn from the center of the wedge plate 2a to the optical axis io. ψ is the apex angle of the wedge plate 2a. And n is wedge plate 2
a is the refractive index. Here, when θ = tan −1 (h / L), each wedge plate 2 is adjusted so as to satisfy the following expression (1).
The apex angle ψ may be determined for each a.

Equation 1 n · sin ・ = sin (ψ + θ) Equation (1)

The above-described method of determining the apex angle of the wedge plate 2a is an example in the case where no optical element having a refracting function such as a concave lens or a convex lens is provided between the illumination plate 2 and the light valve 5. As in the present embodiment, the concave lens 3 and the convex lens 4
When the light source 5 is disposed between the illumination plate 2 and the light valve 5, the light beam emitted from the wedge plate 2a is traced including the behavior when passing through those optical elements, and the wedge plate 2a is traced.
May be determined.

Returning to FIG. 1, the illuminating light incident on the illuminating plate 2 is changed in its traveling direction according to the difference in the apex angle of each wedge plate 2a while maintaining the substantially parallel luminous flux state. It is split into small luminous fluxes of a book. The shape of the cross section of each small light beam along a plane orthogonal to the light beam traveling direction is the shape of each wedge plate 2a.
Defined by the opening defined by Hereinafter, in this specification, the shape of a light beam in a cross section along a plane orthogonal to the light beam traveling direction is simply referred to as “light beam cross-sectional shape”.

The 25 small luminous fluxes divided as described above are converted into luminous fluxes having a predetermined divergent angle through the concave lens 3, and the entire light valve 5 is superimposed and illuminated via the field lens 4. That is, the illumination light emitted from the light source 1 is divided by the number of wedge plates 2a constituting the illumination plate 2, and then illuminates the same illuminated portion on the light valve 5 in a superimposed manner. At this time, as described above, since the outer shape of the wedge plate 2a is in a proportionally reduced relationship with the shape of the illuminated portion of the light valve 5, the cross-sectional shape of each small light beam also has the outer shape of the illuminated portion of the light valve 5. There is a proportional reduction relationship with the shape.
Each small light beam is expanded by the action of the concave lens 3 and the field lens 4, and the size of the cross-sectional shape of each small light beam substantially matches the size of the illuminated portion of the light valve 5.
Thus, the light beam emitted from each wedge plate 2a can illuminate the illuminated portion of the light valve 5 without waste.

As described above, the illumination device I according to the present embodiment comprises the light source 1, the illumination plate 2, the concave lens 3, and the field lens 4.
L1 is configured. Each of the concave lens 3 and the field lens 4 is shown as a single lens, but may be composed of a combination lens. That is, the concave lens 3 can be a diverging optical system composed of a combination lens, and the field lens 4 can be a converging optical system composed of a combination lens.

The light valve 5 is of a transmission type. When a light beam passes through the light valve 5, it is modulated in accordance with an image signal input to the light valve 5, and is modulated via a projection lens 6 described below. The image is projected on the screen 7 as an enlarged projection image.

The projection lens 6 includes a front lens group 6-1, a rear lens group 6-2, and an aperture stop 6-3. The position of the aperture stop 6-3 is determined by the position of the front lens group 6.
-1 so as to coincide with the rear focal position, whereby the entrance side of the front lens group 6-1 (the light valve 5 side)
It has a telecentric configuration. That is, if a light ray passing through the central portion of the aperture stop 6-3 is defined as a principal ray, the principal ray of the light ray incident on the front lens group 6-1 becomes parallel to the optical axis io and passes through the light valve 5. Can be parallel to the optical axis (located at a telecentric position).

As described above, according to the illuminating device according to the first embodiment, only one illuminating plate 2 used for dividing and superimposing a light beam needs to be used, and a predetermined distance is required. It is possible to reduce the size of the entire lighting device as compared with a lighting device according to the related art in which two lens plates are provided (see FIG. 8). Thus, the size of the projection device can be reduced.

By arranging the illumination plate 2 as described above and arranging it on the optical axis io, a substantially parallel light beam incident on the illumination plate 2 from the light source 1 can be converted into a wedge plate constituting the illumination plate 2. The light valve 5 can be illuminated by splitting the substantially parallel light beams in accordance with the number 2a and superimposing the split light beams. For this reason, even if the luminous flux emitted from the light source 1 is uneven, the luminous flux is averaged by the dividing and superimposing action of the illuminating plate 2, thereby suppressing the illuminating unevenness on the light valve 5 and providing a light valve illuminating device with good uniformity. be able to. At this time, the light from the light source 1 can be efficiently guided to the light valve 5 by making the outer shape of the wedge plate 2a have a proportional reduction relationship with the outer shape of the illuminated area of the light valve 5.

In this embodiment, the lighting plate 2 is
Although it was constituted by a plurality of independent wedge plates 2a,
By using the glass pressing technique, an illumination plate having a plurality of wedge plates on the surface can be integrally formed. further,
If a plastic molding technique is used, a cheaper lighting plate can be formed.

In the present embodiment, an example has been described in which the outer shape of the illuminated portion of the light valve 5 is square, and the outer shape of the wedge plate 2a is accordingly square. It may be rectangular.

In the present embodiment, the concave mirror 1 of the light source 1
Although an example in which b is substantially a perfect circle when viewed from the side of the lighting plate 2 has been described, the shape may be an ellipse, an oval, a rectangle, or the like instead. How to determine the length and width of the wedge plate 2a constituting the lighting plate 2 may be as follows. That is, the aspect ratio of the wedge plate 2a is determined so as to substantially match the aspect ratio of the illuminated portion of the light valve 5, and the illumination is performed when the number of aspect ratios when the illumination plate 2 is configured by the plurality of wedge plates 2a is changed. The aspect ratio of the outer shape of the plate 2 is obtained, and the outer size of the illuminating plate 2 when the utilization efficiency of the illuminating light emitted from the light source 1 is maximized, that is, the ideal size is obtained. The numbers of the vertical and horizontal wedge plates 2a and the outer dimensions of the wedge plate 2a may be obtained as close as possible. The specifications of the concave lens 3 and the field lens 3 are determined based on the dimensional ratio between the outer dimensions of the wedge plate 2a determined at this time and the outer dimensions of the illuminated portion of the light valve 5.

As is clear from the above description, the wedge plate 2
The number of rows and columns of a is not necessarily a combination of odd numbers. When both the vertical and horizontal numbers are odd, the wedge plate 2a located at the center of the illumination plate 2 becomes a parallel plane plate. In other cases, all the wedge plates have apex angles corresponding to the arrangement positions. Will have.

Second Embodiment FIG. 4 is a diagram showing a schematic configuration of a lighting device according to a second embodiment of the present invention and a projection device using the lighting device. As can be seen in comparison with the illumination device IL1 according to the first embodiment shown in FIG. 1, the illumination device IL2 according to the second embodiment does not use the concave lens 3 and the field lens 4. In FIG. 4, the same components as those of the lighting device according to the first embodiment shown in FIG. 1 and the projection device using this lighting device are denoted by the same reference numerals, and description thereof will be omitted.

From a light source 11 including a lamp 11a and a concave mirror 11b having a parabolic reflection surface, illumination light of substantially parallel light flux is emitted and enters an illumination plate 12.

In FIG. 5 showing a schematic shape of the lighting plate 12, the lighting plate 12 has a substantially square outer shape. This is because the cross-sectional shape of the illumination light beam emitted from the light source 11 is substantially a perfect circle, and by making the outer shape of the illumination plate 12 a square inscribed in the cross-sectional shape of the illumination light beam,
This is because the light beam emitted from the light source 11 can be used most efficiently. This lighting plate 12 has a total of 20 wedge plates 12a, 5 in length and 4 in width, arranged in a tile shape. When viewed from the optical axis direction, each of the wedge plates 12a has a rectangular shape having substantially the same shape as the image forming portion of the light valve 13, that is, the shape of the illuminated portion.

Each of the twenty wedge plates 12a has its incident side (the back side in FIG. 5) parallel to a plane (ZY plane) orthogonal to the optical axis io, and the incident surface of each wedge plate 12a is
It is arranged so as to be aligned on one plane orthogonal to the optical axis io. That is, the incident side of the illumination plate 12 is a single plane parallel to a plane orthogonal to the optical axis io.

On the other hand, on the emission side (the front side in FIG. 5), each wedge plate 12a has an inclination according to the disposition position of the wedge plate 12a. Since this inclination can be determined in the same manner as described in the first embodiment, the description is omitted here.

Returning to FIG. 4, the illuminating light incident on the illuminating plate 12 is changed in its traveling direction according to the difference in the apex angle of each wedge plate 12a while maintaining the substantially parallel luminous flux state. It is split into small luminous flux of a book. The cross-sectional shape of each small light beam is determined by an opening defined by the outer shape of each wedge plate 12a.

The 20 small light beams divided as described above illuminate the same illuminated portion of the light valve 13 in a superimposed manner. That is, the illumination light emitted from the light source 11 is divided by the number of wedge plates 12a constituting the illumination plate 12, and
The same illuminated portion of the light valve 13 is illuminated in a superimposed manner. At this time, the outer dimensions of the wedge plate 12a are as described above.
Since the outer dimensions of the illuminated portion of the light valve 13 are substantially equal to each other, the cross-sectional shape of each small light flux also substantially matches the outer dimensions of the illuminated portion of the light valve 13. For this reason, it is possible for the small light flux to illuminate the illuminated portion of the light valve 13 without waste.

As described above, the illumination device IL2 according to the second embodiment having the light source 11 and the illumination plate 12
Is composed.

The light valve 13 is of a transmission type. When a light beam passes through the light valve 13, it is modulated in accordance with an image signal input to the light valve 13, and is modulated via the projection lens 6 described below. Projected on the screen 7 as an enlarged projected image.

As described above, according to the illuminating device IL2 according to the second embodiment, the substantially parallel illuminating light emitted from the light source 11 is converted into 20 small luminous fluxes while maintaining the parallel luminous flux state. By dividing and illuminating the same illuminated portion of the light valve 13 in a superimposed manner, a uniform illuminance distribution can be obtained on the surface of the light valve 13. At this time, the lighting plate 12
Can be used, so that the entire lighting device can be reduced in size as compared with a lighting device according to the related art in which two lens plates are disposed at a predetermined distance (see FIG. 8). Become. Thus, the size of the projection device using the lighting device can be reduced.

Further, in the illumination device according to the second embodiment, it is not necessary to use the concave lens 3 and the field lens 4 used in the illumination device according to the first embodiment (FIG. 1). For this reason, it is possible to reduce the manufacturing cost of the lighting device and achieve further reduction in size and weight.

In the second embodiment, the illuminating plate 12 is composed of a plurality of independent wedge plates 2a. However, if a glass press technique is used, a plurality of wedge plates may be formed on the surface. The illuminating plate having the illuminating plate can be integrally formed.
Furthermore, if a plastic molding technique is used, a cheaper lighting plate can be formed.

In this embodiment, the light valve 13
Has been described in which the outer shape of the illuminated portion is rectangular, and accordingly the outer shape of the wedge plate 12a is also rectangular, but both outer shapes may be square.
The number of vertical and horizontal numbers of the wedge plates 12a constituting the lighting plate 12 may be determined as follows. That is, the external shape of the wedge plate 13a is determined so as to substantially match the size of the specific illumination portion of the light valve 13, and the illumination plate when the illumination plate 12 is composed of a plurality of wedge plates 12a is changed in the number of rows and columns. The outer dimensions of the wedge plate 12a may be obtained, and the number of vertical and horizontal wedge plates 12a when the utilization efficiency of the illumination light emitted from the light source 11 is maximized may be obtained.

If the number of vertical and horizontal arrangements of the wedge plates 12a is odd, the wedge plates 12
The fact that a is a plane-parallel plate is the same as in the first embodiment.

Third Embodiment A lighting device according to a third embodiment of the present invention and a projection device using the lighting device will be described with reference to FIG. 6 showing a schematic configuration thereof. The projection devices according to the first and second embodiments described above use one transmission-type light valve. On the other hand, the projection device according to the third embodiment uses a plurality of (three) light valves, and further uses a reflection type light valve. As the illumination device incorporated in the projection device, the type described in the first embodiment as described below, that is, the illumination device in which a concave lens and a field lens are provided behind the illumination plate is used. 6, the same components as those of the lighting device according to the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted.

The white illumination light emitted from the light source 1 enters the illumination plate 2 and is divided into a plurality of small light beams. The cross-sectional shape of the small light beam is determined by the openings defined by the outer shapes of the plurality of wedge plates 2a constituting the illumination plate 2. As described in the first embodiment, the outer shape of the wedge plate 2a has a proportionally reduced shape with respect to the shape of the image forming portions of the light valves 40R, 40G, and 40B, that is, the portions to be illuminated.

A plurality of parallel light beams emitted in a predetermined direction according to the apex angle of each wedge plate 2a constituting the illumination plate 2 enter the cross dichroic mirror 34 with a predetermined spread through the concave lens 3. Cross dichroic mirror 34
Has a B light reflecting dichroic mirror 34B on the optical axis,
The RG light reflecting dichroic mirror 34RG that reflects the R light and the G light is arranged orthogonal to each other. The light beam that has entered the cross dichroic mirror 34 is color-separated into a light beam of B light and a light beam of RG mixed light that travel in directions opposite to each other and perpendicular to the incident optical axis.

The light beam of the color-separated B light travels upward in FIG. 6, is reflected by the bending mirror 35, passes through the B light field lens 4B, and passes through the B light polarization beam splitter 39B.
(Hereinafter, the polarizing beam splitter is referred to as “PBS” in this specification). B incident on PBS39B
The light is reflected by the polarization separation unit inside the PBS 39,
The polarized light is separated into S-polarized light incident on the reflective light valve 40B and P-polarized light that is transmitted and discarded.

FIG. 6 shows the cross dichroic mirror 34B.
The luminous flux of the mixed R and G light reflected downward and traveling is reflected by the bending mirror 36 and enters the G light reflecting dichroic mirror 37. G light reflection dichroic mirror 3
The R and G mixed light beam incident on the G light 7 is reflected by the G light reflecting dichroic mirror 37 and is incident on the G light field lens 4G. And is separated into a light beam of R light incident on.

The light beam of the R light and the light beam of the G light are
After passing through the field lenses 4R and 4G, the PBS 39
The light enters R and 39G, and is separated into S-polarized light and P-polarized light, respectively. Only the S-polarized light of the G light and the R light is incident on the reflection type light valves 40G and 40R, respectively.

As described above, the projection device according to the third embodiment is provided between the concave lens 3 and the field lens 4 of the illumination device IL1 according to the first embodiment shown in FIG.
The configuration is such that a three-color separation optical system is arranged. As described in the first embodiment, it is possible to use a combination lens for the concave lens 3 and the field lens 4 instead of a single lens.

The reflection type light valves 40R, 40G and 40B used in the projection device according to the third embodiment will be described. These reflective light valves 40R,
40G and 40B are electric writing type reflection type light valves. On the other hand, it is possible to use an optical writing type reflection type light valve, but using an electric writing type reflection type light valve is advantageous in terms of miniaturization since an optical writing optical system becomes unnecessary. It is. Therefore, in the present embodiment, only an example using an electric writing type reflection light valve will be described.

The light beam reflected by each of the reflection type light valves 40R, 40G, and 40B becomes a light beam in which P-polarized light as modulated light and S-polarized light as unmodulated light are mixed. These luminous fluxes were transmitted by PBS 39R, 39G and 39G, respectively.
Light incident on B again and transmitted through the polarization splitting unit is extracted as analysis light. The R, G, and B light fluxes extracted as the analysis light, that is, transmitted straight through the PBSs 39R, 39B, and 39G, are transmitted to the cross dichroic prism 41 constituting the color combining optical system for each color light flux. From different incident surfaces. The R, G, and B luminous fluxes that have entered the cross dichroic prism 41 are color-combined and emitted from a surface different from the above-described incident surface,
The light is projected on a screen (not shown) via the projection lens 6. Note that FIG. 6 shows a ray diagram for only the B light of the light flux incident on the illumination plate 2. In this regard, in the projection device according to the third embodiment, each of the reflective light valves 40R, 40G, and 40B
The optical path lengths up to are all the same. Therefore, the ray diagrams of the R light and the G light may be considered to be the same as the B light.

The projection lens 6 has a telecentric structure on the light incident side as described in the first embodiment. Therefore, the principal rays determined by the aperture stop 6-3 (see FIG. 1) of the projection lens are the reflective light valves 40R, 40G, and 40B for each color light, and the PBSs 39R, 39G, and 3B for each color light.
It becomes parallel to the optical axis at the position where 9B is arranged. Thereby, the reflection type light valve 40 for each color light is provided.
R, 40G and 40B and PBS39 for each color light
The problem of the color shading of the projected image which may occur due to the incident angles of R, 39G and 39B can also be suppressed.

As described above, in the third embodiment, the illumination device can be reduced in size, and therefore, the projection device using this illumination device can also be reduced in size. On the other hand, when the illumination device according to the related art is incorporated in the projection device according to the third embodiment, the light source 1 shown in FIG.
Is a large part protruding leftward in FIG.
The miniaturization of the projection device is hindered.

Fourth Embodiment A projection device according to a fourth embodiment will be described with reference to FIG. 7 showing a schematic configuration thereof. The projection device according to the fourth embodiment also uses three reflective light valves 57R, 57G, and 57B as in the projection device according to the third embodiment. On the other hand, a lighting device similar to the lighting device according to the second embodiment is used. The lighting plate 12 and the plurality of light valves 57R, 57G and 5
7B, one polarization beam splitter 53 that also serves as a polarization separation optical system and an analysis optical system, and composite prisms 54 to 56 that also serve as a color separation optical system and a color synthesis optical system. ing. Note that the same components as those of the lighting device according to the third embodiment shown in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.

The illumination light (substantially parallel light beam) emitted from the light source 11 is divided into a plurality of small light beams by an illumination plate 12 having a plurality of wedge plates 12a. The cross-sectional shape of the small light beam is
It is determined by the aperture defined by the outer shape of a.
Each small light beam divided by the illumination plate 12 is substantially parallel light beam in a different direction according to the apex angle of each wedge plate 12a.
Inject more.

The plurality of small luminous fluxes (white light) split upon passing through the illumination plate 12 enter the PBS 53 and are polarized and separated into S-polarized light which is reflected and discarded and P-polarized light which is transmitted. The P-polarized light flux that travels straight through the PBS 53 and exits from the PBS 53 is divided into a first prism 54 and a second prism 55.
And a third color separation prism 56.

A B light reflecting dichroic film is formed on the surface 54b of the first prism 54, and a gap is formed between the first prism 54 and the second prism 55. Further, an R light reflecting dichroic film is formed on the joint surface between the second prism 55 and the third prism 56.

The P-polarized white light flux emitted from the PBS 53 enters from the surface 54a of the first prism, and is reflected by the B light reflecting dichroic film formed on the surface 54b. The remaining luminous flux of the mixed R and G light goes straight without being reflected by the B light reflecting dichroic film and passes through the air gap to the second
The light enters the prism 55.

The P-polarized light flux of the B light reflected by the B light reflecting dichroic film travels in the first prism, and
The light is totally reflected at 4a and travels straight through the first prism 54 again. This light beam is emitted from the surface 54c, and is incident as illumination light on the reflection light valve 57B for B light disposed near the surface 54c.

The luminous flux of the mixed R and G light incident on the second prism 55 travels straight through the second prism 55, and the R light reflecting dichroic formed on the joint surface between the second prism 55 and the third prism 56. The light beam of the R light is reflected by the film. The G light beam passes through the R light reflecting dichroic film, travels straight through the third prism 56, exits from the surface 56a, and enters the G light reflection light valve 57G as illumination light.

The light beam of the R light reflected by the R light reflecting dichroic film goes straight through the second prism 55 and is totally reflected by the surface 55a facing the air gap. The luminous flux of the R light totally reflected by the surface 55a travels straight through the second prism 55, exits from the surface 55c, and is incident as illumination light on a reflection light valve for R light disposed near the surface 55c. I do.

Each light valve 57R, 57G and 57
The luminous flux of each color of R, G, and B reflected by B becomes a luminous flux in which P-polarized light as modulated light and S-polarized light as unmodulated light are mixed. These luminous fluxes respectively follow the incident light path in reverse,
The color is synthesized by the R light reflecting dichroic film and the B light reflecting dichroic film. Then, the light exits from the surface 54a of the first prism 54 constituting the composite prism and is
3 is incident.

The combined light incident on the PBS 53 is
3 is separated into modulated light (S-polarized light) reflected by the polarization splitting unit and incident on the projection lens 6 and unmodulated light (P-polarized light) transmitted through the polarization splitting unit and discarded, that is, analyzed. .

The light detected as described above is projected on a screen (not shown) via the projection lens 6, and a full-color image is formed on the screen. 6 projection lenses
Has a telecentric configuration on the incident side (the PBS 53 side in FIG. 7) as described in the first embodiment, thereby suppressing color shading of the projected image.

In the above-described fourth embodiment, the number and outer shape of the wedge plates 12a may be determined as described in the second embodiment, and are limited to the example shown in FIG. Not something.

In the projection device according to the fourth embodiment, the color separation optical system composed of prisms 54 to 56 is
The optical path length from the light source 11 (illumination plate 12) to each of the reflective light valves 57R, 57G and 57B can be made the same. Therefore, each of the reflection type light valves 57R, 57R,
7G and 57B can be uniformly illuminated. At this time, since only one illumination plate 12 needs to be used, the illumination device IL4 can be reduced in size, and therefore the size of the entire projection device can be reduced. In particular, in the projection device according to the fourth embodiment, the projection device according to the third embodiment has only one polarization separation / analysis optical system, and the concave lens 3 and the field lens 4R , 4G and 4B need not be used. Therefore, it is possible to provide a projection device that is smaller and lighter and can reduce the manufacturing cost.

In the projection devices according to the third and fourth embodiments, a plurality of reflection type light valves are used to project a full-color image. A plurality of transmissive light valves described in (1) may be used.

In the correspondence between the above-described embodiment and the claims, the illuminating plates 2 and 12 are divided light guide means, the cross dichroic mirror 34 and the prisms 54 to 56 are a color separation optical system, and the concave lens 3 is a divergent lens. The optical system and the field lens 4 constitute a converging optical system.

[0069]

According to the first aspect of the present invention, a substantially parallel illumination light beam emitted from a light source is divided into a plurality of small light beams while maintaining a substantially parallel state, and the divided light beams are divided. By guiding a small light beam so that a plurality of small light beams overlap and illuminate substantially the same illumination area of an object to be illuminated, it is possible to provide an illumination device that is small and has very little illumination unevenness. (2) According to the invention described in claim 2, the substantially parallel illumination light beam emitted from the light source is divided into a plurality of small light beams while maintaining a substantially parallel state, and light is written by the plurality of divided small light beams. By guiding a small luminous flux so as to illuminate the bulb in a superimposed manner, it is possible to provide a small-sized projection device with extremely little illumination unevenness. (3) According to the third aspect of the present invention, the cross-sectional shape of the small light beam is made substantially the same as the image forming portion of the light valve, so that the illumination light emitted from the light source is efficiently formed on the light valve. It is possible to provide a projection device which is excellent in energy saving by reducing the luminance required for the light source. (4) According to the invention as set forth in claim 4, the cross-sectional shape of the small light beam is a proportionally reduced shape of the shape of the image forming portion of the light valve, so that the illumination light emitted from the light source can be efficiently transmitted to the light valve. The projection device can be led to the image forming portion, thereby reducing the luminance required for the light source and providing a projection device excellent in energy saving. (5) According to the invention described in claim 5, each of the plurality of divided small light beams can be expanded, and therefore, it is possible to illuminate an area larger than the cross-sectional dimension of the small light beam. Become. Therefore, the light source and the illumination plate can be reduced in size, and the projection device can be reduced in size.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a lighting device and a projection device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a shape of an illumination plate used in the illumination device and the projection device according to the first embodiment.

FIG. 3 is a diagram illustrating a method for obtaining a vertex angle of a wedge plate.

FIG. 4 is a diagram illustrating a configuration of a lighting device and a projection device according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a shape of a lighting plate used in a lighting device and a projection device according to a second embodiment.

FIG. 6 is a diagram illustrating a configuration of a projection device according to a third embodiment of the present invention.

FIG. 7 is a diagram illustrating a configuration of a projection device according to a fourth embodiment of the present invention.

FIG. 8 is a diagram illustrating a configuration of a lighting device according to a conventional technique.

[Explanation of symbols]

1, 11 light source 2, 12 illumination plate 2a, 12a wedge plate 3 concave lens 4, 4R, 4G, 4B field lens 5, 13, 40R, 40G, 40B, 57R, 57G,
57B Light valve 6 Projection lens 6-1 Front lens group 6-2 Rear lens group 6-3 Aperture stop 34 Cross dichroic mirror 41 Cross dichroic prism 37 G light reflecting dichroic mirror 39R, 39G, 39B, 53 Polarizing beam splitter (PBS) ) 54 first prism 55 second prism 56 third prism

Claims (5)

[Claims] A light source that emits a substantially parallel illumination light beam; and a plurality of small light beams while maintaining the illumination light beam in a substantially parallel light state. An illumination device comprising: a divided light guide unit that guides the plurality of small light beams so as to be illuminated by being overlapped with the small light beams. 2. The method according to claim 1, wherein the substantially parallel illumination light beam emitted from the light source is color-separated into light beams of a plurality of colors, and the light beams of the plurality of colors are respectively supplied to a plurality of light valves provided corresponding to the light beams of the plurality of colors. In a projection device that conducts polarization separation, guides light, and modulates and color-combines the light respectively modulated by the plurality of light valves, splits the illumination light into a plurality of small light beams while maintaining a substantially parallel light state. A projection device, comprising: divided light guide means for guiding the plurality of small light beams so as to illuminate each of the plurality of light valves so as to overlap with the plurality of small light beams. 3. The projection device according to claim 2, wherein a cross-sectional shape of the small light beam divided by the divided light guide means in a plane orthogonal to a light beam traveling direction is an image formation of the plurality of light valves. A projection device characterized by having substantially the same outer shape as a part. 4. The projection device according to claim 2, wherein the cross-sectional shape of the small light beam divided by the divided light guide means in a plane orthogonal to the light beam traveling direction is used for image formation of the plurality of light valves. A projection device having a proportionally reduced shape of the outer shape of the portion. 5. The projection device according to claim 4, wherein the plurality of small light beams guided by the divided light guide means are separated between a color separation optical system for color separation and the divided light guide means. A diverging optical system, and a plurality of converging optical systems respectively provided between the color separation optical system and the plurality of light valves.