JP3317298B2 - Illumination optical system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical system for emitting illumination light.

[0002]

2. Description of the Related Art In a projection display device, an image light representing an image is formed from illumination light using an electro-optical device, and the image light is projected to display an image. As this electro-optical device, a light modulation device (emission direction control type light modulation device) that modulates illumination light according to image information (image signal) and emits image light representing an image is used. As an example of the light modulator, a micromirror-type light modulator such as a digital micromirror device (registered trademark of Texas Instruments (TI), hereinafter referred to as "DMD") can be given.

[0003] The DMD has a plurality of micro mirrors corresponding to a plurality of pixels constituting an image. The inclination of each of the plurality of micromirrors changes according to the image information, and reflects light according to the inclination of each micromirror. Of the light reflected by each micromirror, light reflected in a predetermined direction is used as image light. That is, D
The MD is an electro-optical device of the type that forms image light by controlling the direction of light reflection.

FIG. 13 is a schematic structural view of a main part of a conventional projection display device using a micromirror type light modulation device as viewed in plan. The projection display device 5000 includes an illumination optical system 100E and a micromirror light modulation device 200.
And a projection lens 300.

The illumination optical system 100E includes a light source section 110,
A first condenser lens (condensing lens) 120, a color wheel 130, a light-transmitting rod 180A,
And a condenser lens 190.

The light emitted from the light source unit 110 is supplied to a first condenser lens 120, a color wheel 130, a light transmitting rod 180A, and a second condenser lens 190.
And passes through 200 to enter the micromirror-type light modulation device 200. Micromirror type light modulator 2
00 is incident on the micromirror type optical modulator 20.
It is modulated according to the image signal given to 0. The light modulated by the micromirror light modulation device 200 is projected as light (image light) representing an image via the projection lens 300, whereby an image is displayed.

Light emitted from the light source unit 110 often has an uneven illuminance distribution. When such light is used as it is as illumination light, the brightness of the displayed image is often not uniform according to the illuminance distribution of the illumination light. However, it is preferable that the brightness of the image displayed by the projection display device is uniform and bright. Therefore, conventionally, in order to solve this problem, the illumination optical system 1 is used.
In many cases, a translucent rod 180A such as 00E is used. The translucent rod 180A is an optical element having a function of emitting light having a uniform illuminance distribution even when the illuminance distribution of incident light is not uniform.

[0008]

However, the light-transmitting rod 180A is connected to the incident side surface 180 of the light-transmitting rod 180A.
An optical element that makes the illuminance distribution of light emitted from the emission surface side side surface 180AO uniform by passing the light incident from the AI through the light transmission rod 180A while repeating reflection on the inner surface of the light transmission rod 180A. It is. Therefore, in order to make the illuminance distribution of the light emitted from the light-transmitting rod 180A uniform, it is necessary to reflect a large amount of light incident on the light-transmitting rod 180A on the inner surface of the light-transmitting rod 180A. . That is, the translucent rod 180A needs to have a length corresponding to the illuminance distribution of the light emitted from the light source unit 110, and the longer the length, the more preferable. As a result, a projection display device using an illumination optical system using a translucent rod generally has a length of the optical path of the illumination optical system (the physical length of the optical path from the light source to the micromirror type optical modulator). Length), which makes it difficult to reduce the size of the device.

By the way, the brightness of an image displayed by a projection display device largely depends on the illuminance of an illumination area irradiated by light emitted from an illumination optical system. That is, if the illumination optical system emits the same amount of illumination light,
The smaller the area of the illumination area irradiated by the illumination light, the higher the illuminance and the brighter the image displayed by the projection display device. Therefore, it is preferable that the illumination optical system of the projection display device has high illumination efficiency on the light irradiation surface of the electro-optical device. However, when a light modulator (emission direction control type light modulator) such as a DMD is used as an electro-optical device of a projection display device, the illumination of the illumination optical system depends on the positional relationship between the illumination optical system and the light modulator. There is a problem that efficiency is low. In addition, this problem is caused by controlling the emission direction of the illumination light applied to the light irradiation surface (including a plurality of pixels) according to the image information (for each pixel), so that the light that emits the image light representing the image is controlled. This is a problem common to modulation devices.

According to the present invention, a light modulator (emission direction control type light) that emits image light representing an image by controlling the emission direction of illumination light applied to a light irradiation surface for each pixel according to image information. Modulation device), the length of the optical path of the illumination optical system (the physical length of the optical path from the light source to the emission direction control type optical modulator) is shorter than in the past, and the projection is performed. A first object is to provide a technique for reducing the size of a display device. A second object is to provide a technique for improving the illumination efficiency of an illumination optical system.

[0011]

In order to solve at least a part of the above-described problems, an apparatus of the present invention uses a method of emitting illumination light applied to a substantially rectangular light irradiation surface.
Representing an image by controlling the direction according to the image information
For a light modulation device that emits image light, the light irradiation surface
The central axis of the irradiated illumination light is at a predetermined angle with respect to the light irradiation surface.
In the illumination optical system for emitting the illumination light so as to be obliquely incident on the light source unit , wherein the light source unit and the exit surface have a quadrangular shape having first and second diagonal lines having different lengths. Light
A rod, wherein the quadrilateral is the translucent rod.
The ratio of the lengths of the two diagonals of the quadrilateral illumination area irradiated by the illumination light incident on the light irradiation surface is set to be closer to 1 than the ratio of the first and second diagonals. It is characterized by having.

[0012] According to the illumination device, the outline of the quadrilateral illumination area irradiated by the translucent rod can be approximated to a substantially rectangular shape. Therefore, the illumination efficiency of the illumination light can be improved.

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

Embodiments of the present invention will be described below with reference to the drawings. In each of the following embodiments, unless otherwise specified, three directions orthogonal to each other are referred to as the z-axis direction (direction parallel to the optical axis) for convenience.
The direction at 12:00 when viewed from the z-axis direction is the y-axis direction (vertical direction), and the direction at 3:00 is the x-axis direction (lateral direction).

A. First Embodiment FIG. 1 is a schematic configuration diagram of a main part of a projection display apparatus according to a first embodiment of the present invention as viewed in plan. This projection display device 1000A includes an illumination optical system 100D and a micromirror light modulation device 200.
And a projection lens 300. The micromirror light modulation device 200 and the projection lens 300 are arranged such that their respective central axes 200ax, 300ax coincide.

In the illumination optical system 100D, the central axis 100Dax of the illumination optical system is set to the central axis (light irradiation surface) of the micromirror light modulation device 200 due to the restriction of the incident angle of the light illuminating the micromirror light modulation device 200. (Normal line of 202) 20
It is arranged to have a predetermined inclination with respect to 0ax. Here, the “light irradiation surface” refers to a region in which the irradiated light can be used as image light, that is, a light irradiation surface in a narrow sense, which is a region where a micromirror described later is formed.
However, hereinafter, the entire region irradiated with light, including the outside of the region where the micromirror is formed, may be referred to as a light irradiation surface. The "predetermined inclination" is not particularly problematic in the first embodiment, and will not be described, but will be described in detail in the second embodiment.

The illumination optical system 100D includes a light source section 110,
A first condenser lens (condensing lens) 120, a color wheel 130, a second condenser lens (condensing lens) 140, a first lens array 150D,
A second lens array 160D, a superimposing lens 170,
It has. These optical elements 110, 120, 13
0, 140, 150D, 160D, and 170 are sequentially arranged along the central axis 100Dax of the illumination optical system 100D.

The light source section 110 has a light source lamp 112 and a concave mirror 114. The light source lamp 112 is a radiation light source that emits a radial 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 used. The concave mirror 114 is a light source lamp 11
An ellipsoidal concave mirror that emits as condensed light from the opening 116 so that the light emitted from the light source 2 is reflected and enters the first condenser lens 120. As the concave mirror 114, a parabolic mirror that reflects a light beam emitted from the light source lamp 112 and emits it as substantially parallel light may be used.
In this case, the substantially parallel light is transmitted to the first condenser lens 1.
Another condenser lens may be added between the light source unit 110 and the condenser lens 120 so that the light enters the light source 20.

The first condenser lens 120 transmits light from the light source unit 110 to the color wheel 130 in order to reduce a light spot irradiated on the color wheel 130.
Is an optical element for condensing light in the vicinity of.

FIG. 2 shows that the color wheel 130 is
It is the front view seen from 10 side. Color wheel 130
Is divided into three fan-shaped areas separated along the direction of rotation.
The transmission color filters 130R, 130G, and 130B are formed. The first color filter 130R includes:
It has a function of transmitting light in the red wavelength region (hereinafter, referred to as “red light R”) and reflecting or absorbing light in other wavelength regions. Similarly, the second and third color filters 130
G and 130B are light in the green and blue wavelength regions, respectively (hereinafter, referred to as “green light G” and “blue light B”, respectively).
And has a function of reflecting or absorbing light in other wavelength regions. The color filter is, for example, a dielectric multilayer film,
It is composed of a filter plate or the like formed using a dye.

The color wheel 130 is arranged so that the light spot SP condensed by the first condenser lens 120 irradiates a predetermined peripheral position shifted from the central axis 130ax of the color wheel 130. Then, the color wheel 130 is rotated at a constant speed around the rotation shaft 130ax by a motor (not shown). At this time, the light spot SP irradiates each area of the color filters 130R, 130G, and 130B cyclically at regular intervals according to the rotation of the color wheel 130. As a result, the light transmitted through the color wheel 130 is
Red light R, green light G, and blue light B cyclically change according to the rotation of 0.

The second condenser lens 140 of FIG.
Has a function of condensing light transmitted through the color wheel 130 so as to be incident on the first lens array 150D. In the present embodiment, the second condenser lens 140
Is set so that divergent light transmitted through the color wheel 130 becomes substantially parallel light.

The first lens array 150D is a lens array composed of a plurality of first small lenses 152D. The first lens array 150D divides the substantially parallel light emitted from the second condenser lens 140 into a plurality of partial light beams corresponding to the plurality of first small lenses 152, and separates each of the partial light beams. It has a function of condensing light near the second lens array 160D.

FIG. 3 is a front view, a top view, and a side view of the first lens array 150D viewed from the light incident surface side. As shown in FIG. 3A, the first lens array 15
0D is a first small lens 1 which is a substantially rectangular concentric lens.
52D are arranged in a matrix of M rows and N columns. FIG. 3 shows an example where M = 4 and N = 3. “Concentric lens” means a lens whose geometric center and optical center coincide with each other.

The second lens array 160D has second small lenses 162D corresponding to the first small lenses 152D of the first lens array 150D. The second lens array 160D has a function of forming an image of the first lens array 150D on the irradiation surface of the micromirror light modulation device 200 via the superimposing lens 170. In addition, each second small lens 1 of the second lens array 160D
62D can take any shape as long as the corresponding partial light beams emitted from the first lens array 150D can enter. In the present embodiment, a lens array that differs from the first lens array 150D only in the direction of the lens surface (convex surface) is used.

The superimposing lens 170 has a function of superimposing a plurality of partial light beams emitted from the second lens array 160 on the irradiation surface of the micromirror light modulator 200.

First lens array 150D
The plurality of partial light beams emitted from the light source 207 illuminate the light irradiation surface 202 of the micromirror light modulation device 200 through the second lens array 160D and the superimposing lens 170, respectively. Thereby, even when the light emitted from the light source unit 110 has an illuminance distribution, the light irradiation surface 202 is uniformly illuminated.

The micromirror-type light modulation device 200 reflects image light representing an image by reflecting illumination light applied to a light irradiation surface with a micromirror corresponding to each pixel in accordance with an image signal (image information). This is a light modulation device that emits light toward the projection lens 300. Micromirror type light modulator 2
The image light emitted from 00 is projected through the projection lens 300 to display an image.

As described above, the illumination optical system 100D of the projection display apparatus 1000A of this embodiment has the same function as the translucent rod 180A of the conventional illumination optical system 100E (FIG. 14), and the first function. This is realized by an integrator optical system including a lens array 150D, a second lens array 160D, and a superimposing lens 170.

The physical length of the optical path from the first lens array 150D to the micromirror type optical modulator 200 is determined by the optical elements of the first lens array 150D, the second lens array 160D, and the superimposing lens 170. It can be determined by the relationship of the focal length, and does not depend on the illuminance distribution of the light emitted from the light source unit 110. Further, the focal length of each optical element can be freely set to some extent. Therefore, as described in the conventional example, the length of the optical path of the illumination optical system can be shortened as compared with the case where the illumination optical system having the optical path length depending on the illuminance distribution is used. . Thus, the size of the projection display device can be reduced as compared with the related art.

In this embodiment, an example is described in which the plurality of first small lenses 152D of the first lens array 150D are substantially rectangular lenses. However, the present invention is not limited to this. Instead, a lens having a pentagonal or hexagonal outline shape may be used. That is, any shape may be used as long as the light emitted from the light source unit 110 can be divided into a plurality of partial light fluxes.

The second lens array 160D
The small lens 162D is formed of a concentric lens like the first small lens 152D of the first lens array 150D, but is not limited thereto. For example,
The following modifications are possible.

FIG. 4 is a front view showing a modification of the second lens array 160D. In the second lens array 160D ′ shown in FIG. 4, the second small lens 162D ′ is configured by an eccentric lens. The term “eccentric lens” means a lens whose optical center (indicated by +) is shifted from the position of the geometric center (indicated by “印”).

Due to the spherical aberration of the superimposing lens 170 shown in FIG. 1, the plurality of partial light beams split by the first lens array 150D are not efficiently superimposed on the light irradiation surface 202 of the micromirror light modulation device 200. However, the lighting efficiency may be reduced. In such a case, by using the second lens array 160D 'as shown in FIG.
Since the influence of the spherical aberration of the superimposing lens 170 can be suppressed, a plurality of partial light beams can be efficiently superimposed on the light irradiation surface 202 of the micromirror light modulation device 200, and a decrease in illumination efficiency is suppressed. can do.

Also, when the parallelism of the light incident on the first lens array 150D is poor, the illumination efficiency for the light irradiation surface 202 of the micromirror light modulation device 200 may be reduced. In such a case, by configuring the first small lens 152D of the first lens array 150D with an eccentric lens, it is possible to suppress a decrease in illumination efficiency.

Further, the first lens array 150D and the second lens array 160D may be constituted by eccentric lenses.

Further, the projection type display device 100 of the above embodiment
0A shows an example in which the central axis 300ax of the projection lens 300 is arranged so as to coincide with the central axis 200ax of the micromirror light modulator 200, but the present invention is not limited to this. Central axis 300 of projection lens 300
ax is the central axis 20 of the micromirror type optical modulator 200
It may be arranged so as to be shifted from 0ax. In this way, tilt projection can be realized.

Further, the projection type display device 100 of the above embodiment
In the case of 0A, three transmission color filters 130 are used as color wheels 130 in three equally divided regions along the rotation direction.
Although an example in which R, 130G, and 130B are formed is shown, the present invention is not limited to this. For example, instead of dividing into three, the area to be divided may be changed according to the color balance. Also, instead of three divisions, six divisions of red, green, blue, red, green, and blue may be performed. Alternatively, it may be divided into four parts and one of them may be made colorless and transparent. In this case, if the rotation of the color wheel is stopped and the light from the light source unit 110 passes only through the colorless and transparent area, a monochrome image can be displayed. Also, instead of the three color filters of red, green, and blue, colors capable of displaying a color image, for example, cyan,
Three color filters of magenta and yellow may be used. In the present invention, "color filter"
Has a function of transmitting light in a specific wavelength range and reflecting or absorbing light in other wavelength ranges, as well as a function of transmitting light in each wavelength range (a function of a transparent region). Including.

Further, the projection type display device 100 of the above embodiment
0A is a device that includes a color wheel 130 and displays a color image. However, the color wheel 130 may be omitted and a monochrome image may be displayed. In this case, the first condenser lens 120 and the second condenser lens 140 can also be omitted. Also,
What is necessary is just to make the concave mirror 114 of the light source unit 110 a parabolic mirror so that substantially parallel light is incident on the first lens array 150D.

Each optical element 120, 140, 150
The directions of the lens surfaces (convex surface and concave surface) of D, 160D, and 170 are not limited to the directions shown in FIG. The directions can be reversed, and the combination of the directions of the lens surfaces of the optical elements is arbitrary. Further, each of the optical elements 120, 140, 150D, 160D, 170, 30
0 can also be constituted by a compound lens obtained by combining a plurality of lenses. Also, adjacent optical elements can be bonded together to be integrated. For example, the second condenser lens 140 and the first lens array 150D can be bonded and integrated. Further, the second lens array 160D and the superimposing lens 170 can be bonded and integrated. Further, a plurality of optical elements can be replaced with one optical element. For example, the superimposing lens 170 is placed on the second lens array 160D.
And the superimposing lens 170 can be omitted. Further, any of the optical elements can be omitted. For example, the first condenser lens 120 and the second condenser lens 140 can be omitted.

The micro-mirror type optical modulator 200
A prism using internal reflection is provided between the micromirror type light modulation device 200 and the projection lens 300.
2, the image light emitted from the micromirror light modulator 200 may be transmitted and emitted in the direction of the projection lens 300.

The above modifications can be applied to the following embodiments.

B. Second Embodiment FIG. 5 is a schematic configuration diagram of a main part of a projection display apparatus according to a second embodiment of the present invention as viewed in plan. The projection display device 1000 includes an illumination optical system 100, a micromirror light modulation device 200,
And a projection lens 300. The difference from the projection display apparatus 1000A of the first embodiment is that the illumination optical system 100D
Is replaced by the illumination optical system 100, and the other points are the same as those in the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted.

As described in the first embodiment, the illumination optical system 100 has the central axis 1 of the illumination optical system due to the restriction of the incident angle of the light illuminating the micromirror type optical modulator 200.
00ax is arranged so as to have a predetermined inclination with respect to the central axis (normal line of the light irradiation surface 202) 200ax of the micromirror light modulation device 200.

The first lens array 150 is a lens array composed of a plurality of small lenses 152. This first
Of the first lens array 150D
Similarly to (FIG. 1), the substantially parallel light emitted from the second condenser lens 140 is divided into a plurality of partial light beams corresponding to the plurality of small lenses 152, and each of the partial light beams is converted into a second lens. It has a function of collecting light near the array 160.

FIG. 6 is a front view, a top view, and a side view of the first lens array 150 as viewed from the light incident surface side.
As shown in FIG. 6A, the first lens array 150
Has a configuration in which small lenses 152 are arranged in a matrix of M rows and N columns. FIG. 6 shows that M = 4 and N = 3.
Is shown. The outline of the small lens 152 is a lens diagonal 15 connecting the lower left and upper right vertices of the two diagonals.
The length of 2CR1 is a parallelogram longer than the length of the lens diagonal 152CR2 connecting the upper left and lower right vertices. In addition, the small lenses 152 are densely arranged with their sides in contact with each other. Therefore, the first lens array 15
The outline of the entire lens of 0 is also a parallelogram composed of sides parallel to the sides of the small lens 152. The shape of the first lens array 150 will be further described later.

The second lens array 160 has small lenses 162 corresponding to the small lenses 152 of the first lens array 150. Like the second lens array 160D (FIG. 1), the second lens array 160 forms an image of the first lens array 150 on the irradiation surface of the micromirror light modulation device 200 via the superimposing lens 170. It has the function of imaging. Each of the small lenses 162 of the second lens array 160 can have a shape other than a parallelogram as long as the corresponding partial light beams emitted from the first lens array 150 can enter. is there. In this embodiment, a lens array that differs from the first lens array 150 only in the direction of the lens surface (convex surface) is used.

The micromirror-type light modulation device 200 reflects image light representing an image by reflecting illumination light applied to a light irradiation surface with a micromirror corresponding to each pixel according to image information (image signal). This is a light modulation device that emits light toward the projection lens 300. FIG. 7 is an explanatory diagram illustrating a DMD that is an example of the micromirror light modulation device 200. As shown in FIG. 4A, a plurality of micromirrors 204 having a substantially square contour are formed in a matrix on the light irradiation surface 202 of the DMD 200. Each micro mirror 204 is formed to be rotatable within a predetermined angle range with a diagonal line connecting the lower left and upper right vertices as a rotation axis 204c. These micro mirrors 204 correspond to each pixel forming an image.

Here, for the sake of simplicity, the illumination light applied to the light irradiation surface 202 is represented by a representative central ray (incident ray) IR. Also, the illumination light IR
Let h be a horizontal axis parallel to the x-axis, and v be a vertical axis parallel to the y-axis, passing through the incident position on the light irradiation surface 202. In order to simplify the configuration of the device, the illumination light IR applied to the DMD 200 is transmitted to the rotation axis 2 of each micro mirror 204.
It is preferable to have a plane of incidence perpendicular to 04c. For this reason, the illumination light IR applied to the DMD 200
As shown in FIG. 7 (A), as shown in FIG. 7 (A), the inclination θh of the optical path of the illumination light IR projected on the xy plane parallel to the light irradiation surface 202 with respect to the horizontal axis h is approximately 45 degrees diagonally downward to the right. Incident from. As shown in FIG. 7B, the illumination light IR has an incident angle θL to the light irradiation surface 202 of about 2 in a plane perpendicular to the light irradiation surface 202 and including the optical path of the illumination light IR.
The light is incident so as to be 0 degree.

FIG. 7C shows an incident surface including the light incident on the micromirror 204 and the reflected light, that is, an optical path in a cross section perpendicular to the rotation axis 204c. The micro mirror 204 has a plane F parallel to the light irradiation surface 202.
(Shown by a broken line in FIG. 7C).
About ± (θL / 2) degrees (≒ ± 10 degrees).
Note that the angle along the clockwise direction is positive. Illumination light IR
Is + θL (≒) from the normal Fn of the plane F, as described above.
(+20 degrees) enters the micromirror 204 from an inclined direction.

The micromirror 204 is positioned at +
In the state of being inclined by (θL / 2), the illumination light IR is inclined in a direction inclined by −θL from the illumination light IR, that is, the normal line F
It is emitted as reflected light RR (+ θL / 2) in a direction parallel to n. When the micro mirror 204 is tilted by − (θL / 2), the illumination light IR becomes − (3
・ Emitted as reflected light RR (−θL / 2) in a direction inclined by θL). In this way, the illumination light IR applied to the micro mirror 204 is reflected and emitted in different directions according to the rotation angle of the micro mirror 204. For example, when the projection lens is arranged in the direction of the reflected light RR (+ θL / 2), only the reflected light RR (+ θL / 2) is used as image light. As a result, the micro mirror 204
In a state in which the reflected light is projected through the projection lens in a state inclined by (θL / 2), a bright display is realized, and in a state in which the micromirror 204 is inclined by − (θL / 2),
The reflected light is not projected through the projection lens, and a dark display is realized. The intermediate gradation is realized by a method of controlling the ratio of light and dark display in accordance with the gradation during a certain period of time in which one pixel draws an image (a method called pulse width modulation).

Note that the projection type display device 1000 of this embodiment is
, The projection lens 300 is disposed so as to use the reflected light in a state where the micromirror 204 is inclined by + (θL / 2) as image light. Thereby, the image light emitted from the micromirror light modulation device 200 is projected through the projection lens 300 according to the image information, and an image is displayed.

The illumination optical system 100 outputs a red light R, a green light G,
The blue light B is emitted cyclically at regular intervals. At this time, a color image can be displayed by controlling each micromirror 204 of the micromirror light modulation device 200 according to image information corresponding to the irradiated color light.

As described above, the projection display apparatus 1000 of the present invention is characterized by the shape of the first lens array 150. In other words, as shown in FIG. 6, a first lens array 150 and a plurality of small lenses 15
2 is characterized in that it is a parallelogram.
The first lens array 150 is shaped as described above for the following reason.

The micromirror type optical modulation device 200 includes:
As described above, instead of the normal direction of the light irradiation surface 202,
Illumination optical system 1 from a direction having a constant inclination with respect to the normal
The illumination light of 00 is emitted (FIG. 7). FIG. 8 is an explanatory diagram illustrating the illumination light irradiated on the light irradiation surface 202. Assuming that the small lens 152 of the first lens array 150 is formed of a substantially rectangular lens, the light irradiation surface 202
Is not a substantially rectangular shape, but has a shape distorted according to the incident angle.
As described with reference to FIG. 7, the illumination area FI when the illumination light is emitted from the diagonally lower right direction is, as shown in FIG.
A quadrilateral in which the length of the diagonal line FI2 connecting the upper left and lower right vertices is longer than the length of the diagonal line FI1 connecting the upper right and lower left vertices. When the illumination area FI is not substantially rectangular but is distorted, the ratio of invalid light that does not irradiate the light irradiation surface 202 increases. For this reason, the illumination optical system 10
The illumination efficiency of the illumination light emitted from 0 will be reduced. In order to reduce such invalid light, the shape of the illumination light emitted from the illumination optical system 100 may be distorted in advance so that the illumination area FI has a substantially rectangular shape. That is, as shown in FIG. 8B, a cross section R perpendicular to the central axis of the illumination light emitted from the illumination optical system 100.
Of the two diagonals RI1 and RI2 of I, the longer diagonal RI1 is the longer diagonal FI of the distorted illumination area FI
2 and the shorter diagonal line RI2 may be set to correspond to the shorter diagonal line FI1 of the distorted illumination area FI. In other words, the illumination optical system includes an optical element in which the contour shape of the exit surface is a quadrilateral having first and second diagonal lines having different lengths, and this quadrilateral is emitted from the optical element. When the illumination light is obliquely incident on the light irradiation surface at a predetermined angle, two-sided illumination area of the quadrilateral shape irradiated by the illumination light
The ratio of the lengths of the two diagonals may be set closer to 1 than the ratio of the lengths of the first and second diagonals. In this way, the illumination efficiency of the illumination optical system can be improved.

In the projection display apparatus 1000 of the present invention, as shown in FIG. 6, each of the small lenses 152 constituting the first lens array 150 of the illumination optical system 100 has a parallelogram outline shape. ing. The outline of the parallelogram is similar to the cross section RI of the illumination light, and is a cross section diagonal line RI2.
Lens diagonal line 152CR2 of the small lens 152 corresponding to
The length of the lens diagonal 152CR1 corresponding to the cross-section diagonal RI1 is shorter than the length of the lens. Thus, it is possible to reduce invalid light that does not irradiate the light irradiation surface 202. Thereby, the illumination efficiency of the partial light beam emitted from each small lens 152 can be improved. Further, since the small lenses 152 have a parallelogram outline, the small lenses 152 can be densely spread and arranged. Thereby, the light source unit 11
Since the light emitted from the light source unit 110 can be used more effectively, the efficiency of use of the light emitted from the light source unit 110 is high. In this case, in practice, the two lens arrays 150 and 160 are rotated about their respective central optical axes in order to more effectively use the illumination light emitted from the illumination optical system 100. It is preferable to adjust the shape of the illumination area.

In order to further improve the utilization efficiency of the light of each partial light beam emitted from the first lens array 150, each small lens 152 of the first lens array 150 is required.
The cross-section R shown in FIG.
Preferably, the shape is similar to I. By doing so, the illumination area of the partial light beam emitted from each small lens 152 can be made closer to the outline of the substantially rectangular light irradiation surface 202, so that the illumination efficiency of each partial light beam is further improved. be able to. However, in this case, since there is a case where the small lenses 152 cannot be laid out and arranged, the use efficiency of the light emitted from the light source unit 110 may be reduced.

As described above, the projection display apparatus 1000 of the present invention can reduce the ineffective light of the illumination light that illuminates the light irradiation surface 202 of the micromirror light modulation device 200. The illumination efficiency of the illumination light emitted from the system 100 can be improved. Also, the first
As in the embodiment, the illumination optical system 100 includes a first lens array 150, a second lens array 160,
70 is provided. Therefore, the illumination optical system 100 uniformly illuminates the light irradiation surface 202 of the micromirror light modulation device 200, so that an image with uniform brightness can be displayed.
Further, the length of the optical path of the illumination optical system can be reduced as compared with the related art. Thus, the size of the projection display device can be reduced as compared with the related art.

In this embodiment, the DMD shown in FIG. 3 is described as an example of the micromirror type optical modulation device 200, but the present invention is not limited to this. For example, various modes of the incident angle of the illumination light can be considered according to the direction of the rotation axis of the micro mirror 204 and the rotation range. Accordingly, various shapes of the small lens 152 of the first lens array 150 can be considered. For example, when the inclination θL of the illumination light with respect to the normal to the light irradiation surface 202 is larger than the value shown in FIG. 6, the shape of the small lens 152 is a parallelogram in which the ratio of the lengths of the two diagonal lines is larger. It is also possible to use Further, in the present embodiment, the case where the DMD is applied as the micromirror light modulator is described as an example. However, the present invention is not limited to this. Various emission direction control type light modulation devices that emit image light representing an image by reflecting the light in accordance with the above-described method can be used.

The micro-mirror type optical modulator 200
A prism using internal reflection is provided between the illumination optical system 100 and the projection lens 300 so that the illumination light emitted from the illumination optical system 100 is irradiated onto the light irradiation surface 202 of the micromirror light modulation device 200.
To the projection lens 3 while transmitting the image light emitted from the micromirror-type light modulation device 200.
You may make it emit in the direction of 00.

The above modifications can be applied to other embodiments.

C. Third Embodiment FIG. 9 is a schematic configuration diagram of a main part of a projection display apparatus according to a third embodiment of the present invention, as viewed in plan. The projection display device 2000 includes an illumination optical system 100A and a micromirror light modulation device 200.
And a projection lens 300. The difference from the projection display apparatus 1000 (FIG. 5) of the second embodiment is that the illumination optical system 100 is replaced with an illumination optical system 100A.
Other points are the same as in the second embodiment. The same components as those in the second embodiment are denoted by the same reference numerals, and detailed description is omitted.

The difference from the illumination optical system 100 of the second embodiment is that the first lens array 150A and the second lens array 160A are provided between the light source unit 110 and the first condenser lens 120A. It is that you are. The first lens array 150A is the first lens array 150A.
Like FIG. 6, it has a small lens 152A having a parallelogram outline shape. First lens array 150
A divides the condensed light emitted from the light source unit 110 into a plurality of partial light beams. As described above, each of the small lenses 162A constituting the second lens array 160A may have a configuration including the partial light beam emitted from the first lens array 150A. Therefore, the second lens array 160A may have a smaller shape than the first lens array 150A. The function of each optical element is the first
Except for the condenser lens 120A.

The light emitted from the light source unit 110 is divided into a plurality of partial light beams by the first lens array 150A, and enters the first condenser lens 120A via the second lens array 160A. The first condenser lens 120A has a function of superimposing a plurality of incident partial light beams on the color wheel 130 to form a light spot SP. Each partial light beam emitted from the color wheel 130 is supplied to the second condenser lens 140.
, And is superimposed on the light irradiation surface 202 of the micromirror type light modulation device 200.

The projection type display device 2000 of the third embodiment is also
Since the ineffective light of the illumination light illuminating the light irradiation surface 202 of the micromirror light modulation device 200 can be reduced, the illumination efficiency of the illumination light emitted from the illumination optical system 100A can be improved. Further, similarly to the first embodiment, the illumination optical system 100A includes the first lens array 150.
A, an integrator optical system including the second lens array 160A and the superimposing lens 170 is provided. Accordingly, the illumination optical system 100A uniformly illuminates the light irradiation surface 202 of the micromirror light modulation device 200, so that an image with uniform brightness can be displayed. Further, the length of the optical path of the illumination optical system can be reduced as compared with the related art. Thus, the size of the projection display device can be reduced as compared with the related art.

D. Fourth Embodiment: FIG. 10 shows a fourth embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a main part of the projection display device according to the embodiment as viewed in plan. The projection display device 3000 includes an illumination optical system 100B and a micromirror light modulation device 200.
And a projection lens 300. The difference from the projection display apparatus 1000 of the second embodiment (FIG. 5) is that the illumination optical system 100 is replaced with an illumination optical system 100B.
Other points are the same as in the second embodiment. The same components as those in the second embodiment are denoted by the same reference numerals, and detailed description is omitted.

The illumination optical system 100B includes a light source section 110,
First condenser lens 120 and color wheel 1
30, a light-transmitting rod 180, and a second condenser lens 190. The difference from the illumination optical system 100 of the second embodiment is that two lens arrays 150 and 160 are used.
And the translucent rod 18 instead of the superimposing lens 170
0 and a second condenser lens 190.

The illumination light passes through the light transmitting rod 180 while being repeatedly reflected on the inner surface of the light transmitting rod 180.
As a result, even when the illuminance distribution of the light emitted from the light source unit 110 is not uniform, the translucent rod 180 has a function of emitting light having a uniform illuminance distribution from the emission side surface 180O. . That is, the first and second lens arrays 150 and 160 of the illumination optical system 100 and the superimposing lens 1
Similar to 70, it has the function of an integrator optical system. The second condenser lens 190 converts the image on the exit surface of the light-transmitting rod 180 into a micromirror-type light modulator 20.
It has a function of forming an image on the 0 light irradiation surface 202.

FIG. 11 is a perspective view showing the appearance of the translucent rod 180. The light-transmitting rod 180 is
Similar to the small lens 152 (FIG. 3) of the first lens array 150, the contour viewed from the 10 side is a parallelogram quadrangular prism. Thereby, the projection display device 30 of the fourth embodiment
00 can also reduce the invalid light of the illumination light that illuminates the light irradiation surface 202 of the micromirror light modulation device 200. As a result, the illumination efficiency of the illumination light emitted from the illumination optical system 100B can be improved. Further, the micromirror light modulator 2 is controlled by the illumination optical system 100B.
Since the light irradiation surface 202 of No. 00 is uniformly illuminated, an image with uniform brightness can be displayed. In this case, in practice, in order to more effectively use the illumination light emitted from the illumination optical system 100B, the translucent rods 180 are rotated around their respective central optical axes,
It is preferable to adjust the shape of the illumination area.

Further, the light transmitting rod 180 is connected to the light source section 110.
The shape viewed from the side may be similar to the cross section RI shown in FIG. In this way, the illumination area FI of the light emitted from the light transmitting rod 180 is
02 can be made similar to the outline. As a result, the illumination efficiency by the light emitted from the translucent rod 180 can be further improved. The translucent rod 180 has at least only the contour of the exit surface shown in FIG.
It may be formed so as to be similar to the cross section RI shown in FIG. That is, when the light emitted from the light-transmitting rod is obliquely incident on the light irradiation surface at a predetermined angle, the light-transmitting rod has a length of two diagonal lines of the quadrangular illumination area irradiated with the illumination light. The ratio of the heights may be set so as to be closer to 1 than the ratio of at least two diagonals of the exit surface of the translucent rod. In this case, the illumination efficiency by the light emitted from the translucent rod can be improved.

E. Fifth Embodiment FIG. 12 shows a fifth embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a main part of the projection display device according to the embodiment as viewed in plan. The projection display device 4000 includes an illumination optical system 100C, a color light separation / combination prism 400,
Micromirror type optical modulators 200R, 200G,
200B and a projection lens 300. The projection display device 4000 is characterized in that it includes three micromirror light modulation devices 200R, 200G, and 200B and a color light separation / combination prism 400.

The illumination optical system 100C includes a light source 110A.
, The first lens array 150 and the second lens array 1
60 and a superposition lens 170. The difference from the illumination optical system 100 of FIG. 5 is that the light source unit 110 is replaced by a light source unit 110A that emits substantially parallel light, and the first condenser lens 120, the color wheel 130, and the second condenser lens 140 are omitted. That is. Therefore, the illumination optical system 100C emits illumination light including each color light, instead of circulating the red light R, the green light G, and the blue light B unlike the illumination optical system 100.

The light source unit 110A includes a light source lamp 112,
Concave mirror whose concave surface is parabolic (parabolic concave mirror) 114A
And emits substantially parallel light from the opening 116.

The color light separating / combining prism 400 has a configuration in which three prisms 420, 430, and 440 are joined to each other. First prism 420 bonded to each other
Side 420R of the second prism 430
A blue light reflection film BFIL is formed between the light-reflection film and the blue light reflection film BFIL. A red light reflection film RFIL is formed between the side surface 430R of the second prism 430 and the side surface 440I of the third prism 440, which are joined to each other. These reflection films BFIL and RFIL are usually formed of a dielectric multilayer film.

The side faces 430I, 4 of the second prism 430
A micromirror light modulator 200R for red light R is provided on one side surface 430O among the side surfaces excluding the 30R. The illumination optical system 100 of the first prism 420
Side surface 420I on which light from C is incident and second prism 4
Of the side surfaces excluding the side surface 420R joined to the side surface 30, the side surface 420 facing the micromirror light modulation device 200R.
In O, a micromirror light modulator 20 for blue light B
0B is provided. A side surface 440O perpendicular to the central axis 300ax of the projection lens 300 of the third prism 440 is provided with a micromirror light modulator 200G for green light G.
Is provided. These micro-mirror type optical modulators 200R, 200G, 200B are not necessarily
It is not necessary to be provided in contact with 20O, 430O, 440O.

The light including the red light R, the green light G, and the blue light B emitted from the illumination optical system 100C is incident on the side surface 420I of the first prism 420 and is reflected by the blue light reflecting film BFI.
L. For ease of explanation, only the central ray (dashed line) of the light after the color light separation / combination prism 400 is shown as a representative.

The blue light B of the light incident on the blue light reflecting film BFIL is reflected by the blue light reflecting film BFIL. BF
The blue light B reflected by the IL is generally divided into light that passes through the side surface 420I and light that reflects. The blue light B reflected by the side surface 420I enters the micromirror light modulator 200B for blue light B. The blue light reflecting film BF
If the angle of incidence of the light reflected by the IL on the side surface 420I is large, the ratio of the reflected light can be increased. further,
If the angle of incidence is equal to or greater than the critical angle, total reflection can be achieved. Such adjustment of the incident angle can be realized by adjusting the angle between the side surfaces of the prism 420.

The micro-mirror type optical modulation device 200B
The blue image light FB is formed from the incident blue light B and emitted. The blue image light FB emitted from the micromirror light modulation device 200B is reflected by the side surface 420I, further reflected by the blue light reflection film BFIL, and projected by the projection lens 30.
Injected toward zero. Micromirror type light modulator 2
Similarly to the incident light of the blue light B on 00B, if the incident angle of the blue image light FB emitted from the micromirror light modulator 200B on the side surface 420I is large, the ratio of the reflected light can be increased. Further, when the incident angle is equal to or larger than the critical angle, total reflection can be achieved.

On the other hand, the red light R and the green light G of the light incident on the blue light reflecting film BFIL are
The light passes through L and enters the second prism 430. The red light R and the green light G incident on the second prism 430 are
The light enters the red light reflection film RFIL. Red light reflection film RFI
The red light R out of the light incident on L is a red light reflecting film RFI.
The light is reflected by L and enters the blue reflection film BFIL again.
The red light R re-entering the blue reflection film BFIL is usually
The transmitted light passes through the blue reflective film BFIL, but the reflected light increases as the incident angle increases, and the light is totally reflected when the incident angle exceeds the critical angle. Side surfaces 420R and 430I of the first and second prisms 420 and 430 on which the blue reflective film BFIL is formed.
Is set so that the red light R incident on the blue reflection film BFIL again is reflected. Therefore, the red light R incident on the blue reflection film BFIL again is reflected by the blue reflection film BFI.
The light is reflected by L and enters the micromirror light modulator 200R for red light R.

The micromirror type optical modulation device 200R is
A red image light FR is formed from the incident red light R and emitted. The red image light FR emitted from the micromirror light modulation device 200R is incident on and reflected by the blue light reflection film BFIL like the blue light reflection film BFIL. Red image light FR reflected by blue light reflecting film BFIL
Is further reflected by the red light reflection film RFIL, enters the first prism 420, and is emitted toward the projection lens 300 together with the blue image light FB.

On the other hand, the green light G of the light incident on the red light reflecting film RFIL passes through the red light reflecting film RFIL and is incident on the third prism 440. Third prism 440
The green light G incident on the micromirror light modulator 200G for the green light G passes through the third prism 440 from the side surface 440O. The micromirror light modulator 200G converts the green light G incident thereon into the green image light FG.
Is formed and injected. Micromirror type light modulator 20
The green image light FG emitted from 0G passes through the second prism 430 and is incident on the first prism 420, and the projection lens 3 along with the red image light FR and the blue image light FB.
Injected toward 00.

As described above, the color light separating / combining prism 400
From red image light FR and green image light F representing a color image
G and blue image light FB are emitted toward the projection lens 300. Thus, a color image is projected by the projection lens 300.

Each micromirror type optical modulation device 20
The light incident on 0R, 200G, and 200B is incident at a predetermined angle as described with reference to FIG.

The projection type display device 4000 of the fifth embodiment is also
Micromirror type optical modulator 200R, 200G, 20
Since the invalid light of the illumination light that illuminates the 0B light irradiation surface 202 can be reduced, the illumination efficiency of the illumination light emitted from the illumination optical system 100C can be improved. Further, similarly to the first embodiment, the illumination optical system 100C includes the first optical system.
, An integrator optical system composed of a lens array 150, a second lens array 160, and a superimposing lens 170. Therefore, the micromirror light modulators 200R, 200G, 200B are provided by the illumination optical system 100C.
Is uniformly illuminated, so that an image with uniform brightness can be displayed. Further, the length of the optical path of the illumination optical system can be reduced as compared with the related art. Thus, the size of the projection display device can be reduced as compared with the related art.

Further, the projection type display device 400 according to the fifth embodiment.
0 displays a color image by synthesizing the image light emitted from the micromirror light modulators 200R, 200G, and 200B corresponding to the three color lights, respectively. It is possible to display a high-precision color image with less flicker than a projection display device.

It should be noted that the color light separating / combining prism 4 of this embodiment is
00 shows an example constituted by three prisms 420, 430, 440, but is not limited to this. For example, it may be composed of four prisms. That is, the color light separation / combination prism separates the light from the illumination optical system into a plurality of color lights, and causes each of the separated color lights to enter a corresponding one of a plurality of micromirror-type light modulators at a predetermined angle. Any device may be used as long as it combines and emits image light of a plurality of colors emitted from the micromirror light modulation device.

The illumination optical system of the present embodiment is different from the illumination optical system 100B of the fourth embodiment in that the color wheel 13 is used.
Those in which 0 is omitted can also be used.

The present invention is not limited to the above examples and embodiments, but can be implemented in various modes without departing from the scope of the invention.

For example, in the DMD used as the micromirror light modulation device 200 in each of the above embodiments, as shown in FIG. 7, the optical path of the illumination light IR projected on an xy plane parallel to the light irradiation surface 202 is used. The light of the illumination light IR is set so as to face obliquely downward about 45 degrees with respect to the x-axis (horizontal axis h) and includes a light path of the illumination light IR and is perpendicular to the light irradiation surface 202. The case where the incident angle on the irradiation surface 202 is limited to about 20 degrees has been described as an example, but the present invention is not limited to this. For example, the illumination light I
There may be a case where there is a restriction that the optical path of R is set so as to face a direction having an inclination larger than about 45 degrees to the lower right with respect to the x-axis, or a direction having a small inclination. Also, in a plane including the optical path of the illumination light IR and perpendicular to the light irradiation surface, the angle of incidence of the illumination light IR on the light irradiation surface is smaller than about 20 degrees.
Alternatively, it may be a case where there is a restriction of being large. In this case, in the illumination optical system, an optical element whose exit shape is a quadrilateral having first and second diagonal lines having different lengths (in the above embodiment, the first lens array 150 or Light-transmitting rod 180),
When the illumination light emitted from the optical element is obliquely incident on the light irradiation surface at a predetermined angle, the quadrangle has a ratio of the lengths of two diagonal lines of the quadrilateral illumination area irradiated with the illumination light. , May be set to be closer to 1 than the ratio of the lengths of the first and second diagonal lines.

Further, in the above embodiment, the projection type display device using the micromirror type light modulation device has been described as an example. However, the present invention is not limited to this, and the illumination light applied to each pixel is not limited to this. By controlling the emission direction according to the image information, the invention can be applied to a projection display device using various light modulation devices that emit image light representing an image.

[Brief description of the drawings]

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

FIG. 2 is a front view of the color wheel 130 as viewed from a light source unit 110 side.

FIG. 3 is a front view, a top view, and a side view of the first lens array 150D viewed from the light incident surface side.

FIG. 4 is a front view showing a modification of the second lens array 160D.

FIG. 5 is a schematic configuration diagram of a main part of a projection display device according to a second embodiment of the present invention as viewed in plan.

6 is a front view, a top view, and a side view of the first lens array 150 as viewed from the light incident surface side. FIG.

FIG. 7 is an explanatory diagram showing a DMD which is an example of the micromirror light modulation device 200.

FIG. 8 is an explanatory diagram showing illumination light irradiated on a light irradiation surface 202.

FIG. 9 is a schematic configuration diagram of a main part of a projection display device according to a third embodiment of the present invention, as viewed in plan.

FIG. 10 is a schematic configuration diagram of a main part of a projection display according to a fourth embodiment of the present invention, as viewed in plan.

FIG. 11 is a perspective view showing the appearance of a light-transmitting rod 180.

FIG. 12 is a schematic configuration diagram of a main part of a projection display apparatus according to a fifth embodiment of the present invention, as viewed in plan.

FIG. 13 is a schematic configuration diagram of a main part of a conventional projection display device using a micromirror light modulation device as viewed in plan.

[Explanation of symbols]

Reference numeral 100: illumination optical system 100A: illumination optical system 100B: illumination optical system 100C: illumination optical system 100D: illumination optical system 100E: illumination optical system 110: light source unit 110A: light source unit 112: light source lamp 114: concave mirror (elliptical concave mirror) 114A: Concave mirror (parabolic concave mirror) 116: Opening 120: Condenser lens 120A: Condenser lens 130: Color wheel 130R, 130G, 130B: Color filter 140: Condenser lens 150: First lens array 150A: First lens Array 150D: First lens array 152: First small lens 152CR1: Lens diagonal 152CR2: Lens diagonal 152A: First small lens 152D: First small lens 160: Second lens array 160A: Second lens Array 160 .. Second lens array 162 second small lens 162A second small lens 162D second small lens 170 superimposed lens 180 translucent rod 180CR1 rod diagonal 180CR2 rod diagonal 180A translucent Rod 190 Condenser lens 200 Micromirror light modulator 200R, 200G, 200B Micromirror light modulator 202 Light irradiating surface 204 Micromirror 204c Rotation axis 300 Projection lens 400 Color light separating / combining prism 420 430, 440 Prism RFIL Red light reflecting film BFIL Blue light reflecting film FI Illumination area FI1 Diagonal FI2 Diagonal RI RI Cross section of illumination light RI1 Cross section diagonal RI2 Cross section diagonal 1000 1000 Projection display device 1000A Projection Type display device 200 ... projection-type display device 3000 ... projection-type display device 4000 ... projection-type display device 5000 ... projection-type display device

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-11-271706 (JP, A) JP-A-10-170869 (JP, A) JP-A-10-257413 (JP, A) JP-A-10- 115870 (JP, A) JP-A-8-21977 (JP, A) JP-A-10-161120 (JP, A) JP-A-9-160034 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03B 21/14 G03B 21/00

Claims (1)

(57) [Claims] An illumination light applied to a substantially rectangular light irradiation surface.
By controlling the ejection direction of the
The light modulator emits image light representing an image.
The center axis of the illumination light applied to the irradiation surface is located at the light irradiation surface.
The illumination light is emitted so that the light is obliquely incident at a certain angle.
An illumination optical system, comprising: a light source unit; and a light- transmitting rod, which is a quadrilateral having a first and a second diagonal lines having different lengths, wherein the outline shape of the exit surface includes: Entering the light irradiation surface from the translucent rod
An illumination optical system configured such that the ratio of the lengths of two diagonals of the quadrilateral illumination area irradiated by the emitted illumination light is closer to 1 than the ratio of the first and second diagonals; .