JP2003302697A - Lighting device and liquid crystal projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the efficiency of linear polarization of luminous flux emitted by a light source and to improve the use efficiency of luminous flux of an integrator optical system. <P>SOLUTION: The luminous flux emitted by the light source 4 is reflected by a reflector 1 or a front mirror 3 and the reflector 1, and then transmitted through a window 2 of the front mirror 3 and projected toward the integrator optical system 11 to increase the use efficiency of the luminous flux of the integrator optical system 11. Further, the external shape size of an input part of the integrator optical system 11 can be made as large as the size of the window 2 and then the integrator optical system 11 is made small-sized. Further, a 1/4-wavelength plate 18 and a wire grid polarizer 19 are provided on the optical path of the luminous flux traveling toward the integrator optical system 11 and then the efficiency of linear polarization of the luminous flux entering the integrator optical system 11 after being emitted by the light source 4 into linear polarized light is increased. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device using polarized light and a liquid crystal projector using the illuminating device.

[0002]

2. Description of the Related Art Conventionally, in lighting devices that use polarized light and in liquid crystal projectors that use such lighting devices, various measures have been taken to reduce the loss of luminous flux and increase the lighting efficiency.

An example of such an illuminating device is disclosed in Japanese Patent Application Laid-Open No. 11-6989. The illuminating device disclosed in Japanese Patent Laid-Open No. 11-6989 will be described with reference to FIGS. 17 and 18.

The lighting device shown in FIG. 17 is a light source 1 such as a metal halide lamp, a halogen lamp, a xenon lamp, or the like.
01, a parabolic mirror 102 that is a reflector, a spherical mirror 104 having a window 103, a quarter-wave plate 105, a wire grid polarizer (hereinafter abbreviated as a WG polarizer) 106, and the like. The light source 101 is disposed on the focal point of the parabolic mirror 102, and the focal point and the spherical center of the spherical mirror 104 are aligned with each other, and the spherical mirror 104 causes the luminous flux other than the luminous flux directly guided from the parabolic mirror 102 to the illumination target. Light source 10
It is returned to 1 and reflected again by the parabolic mirror 102 to guide it to the illumination target. The quarter-wave plate 105 and the WG polarizer 106 are arranged in a direction perpendicular to the optical axis of the light reflected by the parabolic mirror 102. An integrator optical system (not shown) that uniformly illuminates an illumination target is disposed behind the quarter-wave plate 105 and the WG polarizer 106 along the traveling direction of the light flux.

The illumination device shown in FIG. 18 uses an ellipsoidal mirror 107 as a reflector, and a light source 101 is arranged on one focus of the ellipsoidal mirror 107. Spherical mirror 104
And a quarter-wave plate 105, a collimator lens 108 for arranging the light reflected by the ellipsoidal mirror 107 and condensed on the other focal point into parallel light is disposed. Of the ellipsoidal mirror 107.
The luminous flux other than the luminous flux directly guided to the illumination target from the spherical mirror 1
The light is reflected by 04 and returned to the light source 101, and again reflected by the ellipsoidal mirror 107 to be guided to the illumination target. 1/4
The wave plate 105 and the WG polarizer 106 are the ellipsoidal mirror 107.
Are arranged in a direction that intersects perpendicularly with the optical axis of the light reflected by.

The quarter-wave plate 105 and the WG polarizer 106 constitute a polarization conversion optical system, and this polarization conversion optical system converts random polarized light into one polarized light (P polarized light) by the WG polarizer 106. The light is transmitted and the other polarized light (S polarized light) is reflected. The reflected polarized light (S polarized light) is a quarter wavelength plate 1
In 05, the light is converted into circularly polarized light and the reflector (parabolic mirror 102
Or, it is returned to the ellipsoidal mirror 107). The circularly polarized light returned to the reflector passes through the light source 101 after being reflected there,
It behaves in the same manner as the first emitted light beam and is returned to the polarization conversion optical system again. However, since it is converted from circularly polarized light into one polarized light (P polarized light) by the quarter-wave plate 105, the WG polarizer 1
At 06, it is transmitted as it is. According to this idea, all the light fluxes made into parallel light are converted into linearly polarized light.

However, this idea holds when the light source 101 is a point light source, and such a light source cannot be obtained in practice. That is, the light source having a certain volume must be used, and the parabolic mirror 10 is used as the reflector.
Emitting with a certain divergence angle (when the size of the reflector is considered to be not larger than a certain size from the practical use requirement, about 5 to 7 ° must be allowed) even if parallel light is used with 2. To be done. Further, since the spherical mirror 104 is used as a mirror for returning the light flux, the divergence angle becomes larger when reflected here,
After that, the utilization efficiency of the light flux in the integrator optical system for uniformly illuminating the illumination target is reduced.

[0008]

Here, the problems of the conventional example shown in FIG. 17 will be described in detail in relation to the present invention with reference to FIG. Assuming that the included angle of the parabolic mirror 102 is θ, the angle covered by the spherical mirror 104 is between θ and the angle θ ′ from the edge of the window. However, even if θ ′ is large, the reflected light will fall into the support hole 109 of the light source 101, so that the angle is substantially up to θ ″. Further, the window 103 should not block the parallel light reflected by the parabolic mirror 102. Since θ must be opened, θ ′ will continue to be limited.
On the contrary, if this θ ′ is to be increased, the radius r of the spherical mirror 104 must be increased and the entire outer shape (diameter D,
The length L) in the z direction becomes large.

Further, the divergence angle α of the light beam passing through the window 103 of the spherical mirror 104 as parallel light directly from the parabolic mirror 102.
Varies depending on the relationship between the size of the light emitting portion of the light source 101 and the F value (focal length) of the parabolic mirror 102, but it is practically set to 5 to 7 ° in consideration of the efficiency of the integrator optical system in the subsequent stage. (If the F value is extremely large with respect to the size of the light emitting portion of the light source 101 in the z-axis direction, the divergence angle α will be small, but this will increase the outer shape of the parabolic mirror 102. , The F value is set to 4 to 8 times the size of the light emitting portion of the light source 101 in the z-axis direction).

Here, the light-emitting portion of the light source 101 directly enters the spherical mirror 104, is reflected there, passes through the vicinity of the light source 101, is reflected by the parabolic mirror 102, and then is reflected by the spherical mirror 1.
A light flux passing through the window 103 of No. 04 will be described. The light flux reflected by the spherical mirror 104 is returned at a divergence angle α ′ that is approximately the same as the divergence angle α described above, but the parabolic mirror 102 is reflected by a portion having a large curvature, and thus the divergence angle β ′ and It passes through the window 103 at a large angle. This reduces the utilization efficiency of the luminous flux in the integrator optical system in the subsequent stage.

Next, the WG polarizer 106 (see FIG. 17)
The behavior of the light flux reflected by is explained. WG polarizer 1
The light flux reflected by 06 is directed to the focal point of the parabolic mirror 102 (the light source 101 by a path opposite to that when traveling toward the WG polarizer 106 side).
Behavior), and the subsequent behavior is the same as the luminous flux emitted from the light source 101. Therefore, the parabolic mirror 10
The light directly reflected from the beam No. 2 is reflected again by the parabolic mirror 102 and recurred, whereas the light flux obtained through the spherical mirror 104 is recurred again through the spherical mirror 104, so that the divergence angle is large. As a result, the utilization efficiency of the integrator optical system decreases.

Next, the problems of the conventional example shown in FIG. 18 will be described in detail in relation to the present invention with reference to FIG.
The relationship between the inclusion angle θ of the ellipsoidal mirror 107 and the angle (θ′−θ) covered by the spherical mirror 104 is the same as that described with reference to FIG. 19, and the relationship with the support hole 109 of the light source 101 is also the same, so the illustration is omitted. Although omitted, the relationship with θ ″ is the same as in the case of FIG.
It is possible to set from the outer edge of 7 to the intersection point with the line toward the second focal point of the ellipse, and the spherical mirror 104 can be made larger than in the case of FIG. In any case, if θ ′ is increased, the entire outer shape (diameter D, length L in the z direction) is increased as in the case of FIG.

Even in such a structure, the behavior of the light beam emitted from the light source 101 is the same as that in the case of FIG.
The divergence angle of the light flux that reaches the second focus after passing through the spherical mirror 104 becomes extremely larger than the divergence angle α of the light flux reflected only by the ellipsoidal mirror 107, and the collimator lens 108 provided after that makes the light parallel. And the utilization efficiency of the light flux in the integrator optical system in the subsequent stage is reduced.

Next, the WG polarizer 106 (see FIG. 18)
The behavior of the light flux reflected by is explained. First, WG
In the case where the polarizer 106 is placed after the collimator lens 108, the luminous flux reflected by the WG polarizer 106 is W
The light is returned to the focal point of the ellipsoidal mirror 107 (the position of the light source 101) in the route opposite to that when traveling to the G polarizer 106 side, and the behavior thereafter is the same as the light emission from the light source 101. However,
The light directly reflected from the ellipsoidal mirror 107 is again reflected by the ellipsoidal mirror 107.
In contrast to the case where the light flux is reflected by and recurred by, the luminous flux obtained through the spherical mirror 104 is re-reflected through the spherical mirror 104 again, so that the utilization efficiency is extremely lowered (effective by the square).

The WG is placed on the second focal point of the ellipsoidal mirror 107.
When the polarizer 106 is arranged, the behavior on the ellipsoidal mirror 107 side from the second focal point is W after the collimator lens 108, except that it is reflected by an axis symmetrical with the z axis as an axis.
This is the same as when the G polarizer 106 is arranged. However, since it never passes through the collimator lens, a decrease in efficiency can be avoided.

An object of the present invention is to improve the efficiency of linear polarization of a light beam emitted from a light source and to improve the light beam utilization efficiency in an integrator optical system.

[0017]

The invention according to claim 1 is
In a lighting device in which a light source is arranged in the vicinity of the focal point of the reflector, and a light flux emitted from the light source and reflected by the reflector is emitted toward an integrator optical system, the light source is orthogonal to the optical axis of the reflector and faces the reflector. And a front mirror having a window having a light-transmitting property, which is approximately the same size as the external size of the input section of the integrator optical system and is formed in the center, in the traveling direction of the light flux emitted from the window. And a quarter wave plate and a wire grid polarizer, which are sequentially arranged in front of the integrator optical system.

Therefore, the luminous flux emitted from the light source is
After being reflected by the reflector or after being reflected by the front mirror and the reflector, the light passes through the window of the front mirror and is emitted toward the integrator optical system. As a result, the utilization efficiency of the light flux in the integrator optical system is increased. Further, the outer size of the input section of the integrator optical system can be made equal to the size of the window, and the integrator optical system can be downsized. Further, by providing the quarter-wave plate and the wire grid polarizer, it is possible to enhance the efficiency of linear polarization for aligning the light flux emitted from the light source and entering the integrator optical system into one linear polarization.

According to a second aspect of the invention, in the illumination device according to the first aspect, the integrator optical system is of a type in which light beams divided into a plurality of optical axes are superposed on an illumination target.

Therefore, even when the integrator optical system of this type is used, the operation and effect of the invention according to claim 1 can be obtained.

According to a third aspect of the invention, in the illumination device according to the first aspect, the integrator optical system is of a lot type.

Therefore, even when the integrator optical system of this type is used, the operation and effect of the invention according to claim 1 can be obtained.

The invention according to claim 4 is the same as claims 1 to 3.
In the illumination device according to any one of items 1 to 3, the reflector is a parabolic mirror, and the front mirror is a plane mirror.

Therefore, the parallelism of the light beam passing through the window can be increased, and the utilization efficiency of the light beam in the integrator optical system can be sufficiently increased.

The invention as defined in claim 5 is defined by claim 1 through claim 3.
In the illumination device according to any one of items 1 to 3, the reflector is a parabolic mirror, and the front mirror is a parabolic mirror sharing a focus with the reflector.

Therefore, the parallelism of the light beam passing through the window can be increased, and the utilization efficiency of the light beam in the integrator optical system can be sufficiently increased. Further, the light flux first reflected by the parabolic mirror, which is the front mirror, after being emitted from the light source can also be transmitted through the window as parallel light, and the utilization efficiency of the light flux in the integrator optical system is further enhanced.

The invention according to claim 6 is the invention according to claims 1 to 3.
In any one of the illumination devices, the reflector is an ellipsoidal mirror, and the front mirror is a plane mirror arranged on a minor axis of the ellipsoidal mirror.

Therefore, the luminous flux emitted from the light source can be efficiently condensed at the second focal point of the ellipsoidal mirror, and the collimator lens or the like collimates the luminous flux to use the luminous flux in the integrator optical system. The efficiency can be increased sufficiently.

The invention according to claim 7 is the invention according to claims 1 to 3.
In the illumination device according to any one of items 1 to 3, the reflector is an ellipsoidal mirror, and the front mirror is a spherical mirror having a second focus of the ellipsoidal mirror as a spherical center.

Therefore, the luminous flux emitted from the light source can be efficiently focused on the second focal point of the ellipsoidal mirror, and the collimator lens or the like collimates the luminous flux to use the luminous flux in the integrator optical system. The efficiency can be increased sufficiently.

The liquid crystal projector according to an eighth aspect of the present invention is any one of the first to seventh aspects, wherein at least one liquid crystal panel on which an image to be projected by the image information control unit is formed, and the liquid crystal panel is illuminated as an illumination target. The lighting device according to any one of claims 1 to 5 and a projection lens for projecting an image of the liquid crystal panel on a screen.

Therefore, since the liquid crystal panel is illuminated by using the illuminating device according to any one of claims 1 to 7, it is possible to illuminate the liquid crystal panel under illumination having a high luminous flux utilization efficiency. The projection lens having a small aperture can be projected on the screen, and the liquid crystal projector as a whole can be miniaturized.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION First, the invention principle A of the present invention is shown in FIG.
It will be described based on. The principle A of the present invention is a case where the parabolic mirror 1 is used as the reflector and the plane mirror 3 is used as the front mirror with the window 2.

If the included angle θ of the parabolic mirror 1 is equal to or smaller than the angle θ ″ formed with the support hole 5 of the light source 4, there is no problem even if the outer shape (diameter D) is made as large as possible. The size of the window 2 of the front mirror with window 3 must be such that the parallel light reflected at a right angle from the intersection with the Y axis of the parabolic mirror 1 is not blocked. If the F value is f, w / 2> 2f must be satisfied, and the light flux from the origin (light source 4) emitted on the Y-axis and X-axis plane is repeatedly reflected by the plane mirror 3 many times and emitted from the window 2. In this state, the utilization efficiency of the luminous flux emitted from the light source 4 is extremely reduced.

A plane mirror 3 is formed as parallel light directly from the parabolic mirror 1.
It is assumed that the divergence angle α of the light flux passing through the window 2 is 5 to 7 °, which is the same as the description of FIG.

Here, when the light flux reflected by the parabolic mirror 1 enters the plane mirror 3, it is reflected there, but the divergence angle α '.
Will be returned as it is. This light beam is reflected by the parabolic mirror 1 again, but the angle β '
Is reflected and reflected. Further, the light passes through the vicinity of the light source 4 and is again reflected by the parabolic mirror 1 again to have a divergence angle of δ ′ and pass through the window 2 of the plane mirror 3. Since this divergence angle δ ′ is almost the same as the divergence angle α of the light beam directly reflected by the parabolic mirror 1, the utilization efficiency in the integrator optical system in the subsequent stage is similar to that of the light beam directly reflected by the parabolic mirror 1. This is the same, and the utilization efficiency of this light flux is not reduced. In other words,
This method is affected only by the decrease in the reflectance between the plane mirror 3 and the parabolic mirror 1, and the inclusion angle θ− ^ θ ″ (where ^ θ ″ is
Means a symbol with a minus sign above θ ″ in FIG. 1)
The luminous flux emitted during the period can be efficiently used. When the entire outer shape (diameter D, length L in the z direction) is set to the same level as in FIG. 19, the utilization efficiency of the luminous flux is obviously higher than that in the configuration shown in FIG.

Next, as shown in FIG. 5 described later, the plane mirror 3
1/4 wave plate 18 and WG to cover the window 2 of
The behavior of the light reflected by placing the (wire grid) polarizer 19 vertically on the z axis will be described. Also in this case, WG
The light flux reflected by the polarizer 19 is returned to the focal point of the parabolic mirror 1 by a route opposite to that when traveling to the WG polarizer 19 side, but since the behavior thereafter is similar, it is directly reflected from the parabolic mirror 1. The divergence angle α ′ of the same degree for both the retroreflected light flux from the reflected light flux and the light flux recurred from the light flux that has passed through the plane mirror 3.
Since it becomes δ ′ and passes through the window 2 of the plane mirror 3 again, it can be used without lowering the utilization efficiency in the integrator optical system in the subsequent stage.

Next, the inventive principle B of the present invention will be described with reference to FIG. The principle B of the invention is a case where the parabolic mirror 1 is used as the reflector and the parabolic mirror 6 is used as the front mirror with the window 2. The focal length F2 of the parabolic mirror 6 is preferably in the range of 2 to 4 times the focal length F1 of the parabolic mirror 1, and the focal position of the parabolic mirror 6 and the focal point of the parabolic mirror 1 are good. Match the position. In this case, the entire included angle can be up to θ ′ to the edge of the window 2 of the parabolic mirror 6. However, it is necessary to make the angle smaller than the angle θ ″ affected by the edge of the support hole 5 of the light source 4. With this configuration, in addition to the light flux directly reflected by the parabolic mirror 1 and passing through the window 2, Parabolic mirror 1 and parabolic mirror 6
The light flux reflected by and then reflected again by the parabolic mirror 1 and passing through the window 2 and the light flux reflected by the parabolic mirror 6 to the parabolic mirror 1 and then again by the parabolic mirror 1. Two systems occur with the light flux passing through the window 2. In each case, the number of reflections is reduced by one compared with the configuration of FIG. The divergence angle δ ′ of the light flux emitted through the parabolic mirror 6 once is wider than that of FIG. 1 if the parabolic mirror 1 has the same F value. However, if the outer shapes (diameter D, length L in the z direction) are made approximately the same, in the case of the present invention principle B, the F value of the parabolic mirror 1 can be increased by 30 to 50%, so the divergence angle δ ′. Can be almost the same. Further, as a result of increasing the F value, the divergence angle α itself of the directly reflected light beam from the parabolic mirror 1 is relatively small, so that not only the case shown in FIG. The utilization efficiency of the luminous flux in the system is remarkably improved.

Next, the quarter wavelength plate 18 and the WG polarizer 19 are placed vertically on the z axis so as to sufficiently cover the window 2 of the parabolic mirror 6 (see FIG. 12). In this case as well, the light flux reflected by the WG polarizer 19 is returned to the focus of the parabolic mirror 1 in a path opposite to that when traveling toward the WG polarizer 19, but the subsequent behavior is emitted from the light source 4. Since it is the same as the luminous flux, the retroreflected luminous flux from the direct reflected luminous flux from the parabolic mirror 1 is also included.
The light beam recurred via the beam also has a divergence angle similar to the divergence angles α and δ ′, and again passes through the window 2 of the parabolic mirror 6. That is, the light flux that has recurred is also used without lowering the efficiency of use in the integrator optical system in the subsequent stage.

Next, the inventive principle C of the present invention will be described with reference to FIG. The principle C of the present invention is a case where the ellipsoidal mirror 7 is used as the reflector and the plane mirror 3 is used as the front mirror with the window 2.

The plane mirror 3 is a minor axis surface (X'Y 'of the ellipsoidal mirror 7).
Are arranged on the surface). Also in this case, the included angle can be set to the edge of the window 2 of the plane mirror 3 and can be set to θ ′. Also here, it is meaningless unless θ ′ is smaller than θ ″.

With such a configuration, in addition to the light beam directly reflected by the ellipsoidal mirror 7 and passing through the window 2, it is reflected by the ellipsoidal mirror 7 and the plane mirror 3 and then reflected again by the ellipsoidal mirror 7. Two systems are generated: a light beam that is passed through the window 2 and a light beam that is reflected from the plane mirror 3 to the ellipsoidal mirror 7 and then reflected by the ellipsoidal mirror 7 and passes through the window 2. In each case, the number of reflections is one more than that of the configuration of FIG. 20, but the divergence angle δ ′ of the light flux emitted through the plane mirror 3 once is the same as that of the ellipsoidal mirror 7 in FIG. The configuration is almost the same. However, if the outer shapes (diameter D, length L in the z direction) are made approximately the same, the F value can be increased by several tens of percent, so that not only the divergence angles δ ′ and δ ″ can be made relatively small, Since the divergence angle α of the directly reflected light flux can be made relatively small,
The utilization efficiency of the light flux in the latter-stage integrator optical system is remarkably improved as compared with the case of FIG.

The relationship between the included angle θ'and the maximum incident angle φ in this configuration is just ψ = π-θ '. In this configuration, 1/4
There are two places where the wave plate and the WG polarizer can be arranged. Similar to the description of FIG. 20, the collimator lens is placed after the second focal point at one location to make parallel light and then placed vertically with respect to the light flux. The behavior of the light flux reflected by the WG polarizer is shown in FIG. Similar to the description, it returns to the WG polarizer again. At that time, since the polarized light is transmitted therethrough, all the light fluxes passing through the plane mirror 3 are aligned to one polarized light and supplied to the next stage. At the other location, a WG polarizer having the same shape as the window 2 is placed on the same surface as the plane mirror 3, and a quarter wave plate having the same shape is closely attached and arranged immediately before. In this case, only one polarized light passes through the window 2 and the other polarized light is reflected. This has the same effect as if there is a one-sided plane mirror, and the other polarized light can be used for the light flux directly entering this area from the light emitting portion of the light source 4. However, once the plane mirror 3
The light flux that has passed through the
Since it passes through the vicinity and enters the support hole 5 of the light source 4, it does not become a retroreflected light.

Next, the inventive principle D of the present invention will be described with reference to FIG. The principle D of the invention is a case where the ellipsoidal mirror 7 is used as the reflector and the spherical mirror 8 having the second focus of the ellipsoidal mirror 7 as a spherical center is used as the front mirror with the window 2.

In this arrangement, the effect that the spherical mirror 104 is used as the front mirror in FIG. 20 has almost no effect, but the effect is remarkably improved by conversely using the cause. That is, an ellipsoidal mirror 7 is used as a reflector, and a spherical mirror (convex mirror) 8 having its second focus as a spherical center is arranged as a front mirror, and the XY plane on the first focus of the z axis and the ellipsoidal mirror 7 intersect. And the window 2 is provided so that the edge of the window is located outside the conical shape formed by the straight line connecting the second focus.

In this way, the light beam reflected by the mirror surface p1 of the ellipsoidal mirror 7 goes to the second focal point at the divergence angle α ', but is reflected by the spherical mirror 8 on the way and further widened to the divergence angle β'and p1.
Returned to. Here, again, the light is reflected in the direction of the light source 4, but is narrowed in the opposite direction to the divergence angle γ '. Since this divergence angle γ'is gentle, the divergence angle δ'after being reflected again by the ellipsoidal mirror 7 is also gradual and becomes about the same angle as the divergence angle α, so that the collimator lens thereafter is used. The luminous flux does not deteriorate the efficiency at 9 and the efficiency at the integrator optical system.

Also in this configuration, there are two places where the quarter-wave plate and the WG polarizer can be arranged. As in FIG. 20, the collimator lens 9 is placed after the second focal point at one location to make parallel light and then placed vertically with respect to the light flux. The behavior of the light flux reflected by the WG polarizer is described in FIG. It becomes the same as and returns to the WG polarizer again. At this time, since the polarized light is transmitted therethrough, all the light fluxes having passed through the spherical mirror 8 are aligned to one polarized light and supplied to the next stage. At the other location, a WG polarizer having the same shape as the window 2 is placed on the same surface as the spherical mirror 8, and a quarter wave plate having the same shape is closely attached and arranged immediately before. In this case, only one polarized light passes through the window 2 and the other polarized light is reflected. However, in this case,
The position of the WG polarizer may not be on the same plane as the spherical mirror 8. That is, for example, the position of M'or M "is also acceptable. However, it is not realistic for the light beam to enter the ellipsoidal mirror 7 from the side closer to the ellipsoidal mirror 7 than M like M '.
It can be arranged anywhere if it is formed in a spherical mirror shape having the second focus as the spherical center on the outer side.

Although the effects in the above description are qualitatively described, they have been confirmed by experiments and simulations, and the order of the described effects is almost the same.

Next, the first embodiment of the present invention will be described with reference to FIG.
It will be described based on. In addition, each embodiment described below is based on the invention principle A to A described in FIGS. 1 to 4 described above.
Any one of D is used, and the description of the parts of the inventive principles A to D described in FIGS. 1 to 4 will be omitted.

The illumination device according to the present embodiment utilizes the invention principle A shown in FIG. 1, and directly collimates the parallel light produced by the parabolic mirror 1 which is a reflector.
I put it in. However, in this case, all the light fluxes emitted from the light source 4 cannot be used, so that the light fluxes which do not directly enter the integrator optical system 11 are parabolic mirrors 1.
It is returned to the parabolic mirror 1 side again by the plane mirror 3 which is a front mirror placed vertically on the parallel light created by. The returned light flux is returned by the parabolic mirror 1 to its focal point, that is, the light emitting position of the light source 4. The light source 4 used here is a high pressure mercury lamp,
Since it is an arc lamp such as a metal halide lamp or a xenon lamp, the returned luminous flux passes through between the electrodes (actually, the focus that can be made here is the image of the light source 4, which is slightly larger than the image of the light source when the light is first emitted. Therefore, a part of the light flux is shielded by the electrodes), reaches the mirror surface of the parabolic mirror 1, and then becomes parallel light and passes through the window 2 of the plane mirror 3 toward the integrator optical system 11.

The plane mirror 3 is formed by forming a mirror surface on a part of the inner surface of the front glass 12 that closes the exit portion of the parabolic mirror 1, and has substantially the same size as the external size of the input section of the integrator optical system 11. Window 2 is formed in the center. AR coating may be applied to the portion of the window 2 to increase the light transmission efficiency.

The integrator optical system 11 will be described.
This integrator optical system 11 is disclosed, for example, in Japanese Patent Laid-Open No. 3-11.
This is a well-known structure disclosed in Japanese Patent No. 1806, and is composed of a pair of fly-eye lenses 13 and 14, and each fly-eye lens 13 and 14 is formed by arranging two cylindrical lens arrays orthogonally. There is. The fly-eye lens described in Japanese Patent Laid-Open No. 3-111806 is composed of a pair of orthogonal cylindrical lenses in the present embodiment, and various effects can be obtained by such a structure. However, since it is not directly related to the present invention, in order to simplify the description, in the following description, the lens of the present embodiment configured by a pair of cylindrical lenses will be referred to as a fly-eye lens for description. Rear fly-eye lens 1
A superimposing lens (convex lens) 15 is arranged in the subsequent stage of 4,
It serves to superimpose the light beams divided by the fly-eye lenses 13 and 14 on the liquid crystal panel 16 which is an irradiation target.

Front glass 12 and integrator optical system 1
Between 1 and 1, UV / IR cut filter 17, 1/4
A wave plate 18 and a WG (wire grid) polarizer 19 are inserted vertically to the optical axis. In this figure, for convenience of description, the quarter-wave plate 18, the WG polarizer 19 and the fly-eye lens 13 are separated from each other, but the space can be effectively used by closely contacting them.

The light beam emitted from the light source 4 and then reflected by the parabolic mirror 1 and emitted from the window 2 of the plane mirror 3 is a randomly polarized light, and the UV / IR cut filter 17 cuts ultraviolet rays and infrared rays. As a result, only visible light is transmitted and is transmitted through the quarter-wave plate 18 (even if the randomly polarized light passes through the quarter-wave plate 18, only the polarization plane is modulated, and the random polarized light still remains). Is). The WG polarizer 19 transmits one polarized light (here, S polarized light) and reflects the other polarized light (P polarized light) toward the quarter wavelength plate 18 side. That is, each of these light fluxes is linearly polarized light. 1 linearly polarized light reflected
Circularly polarized light after passing through the quarter-wave plate 18 and UV
/ IR cut filter 17, transmitted through the front glass 12 and reflected by the parabolic mirror 1, transmitted between the electrodes of the light source 4, reflected again by the parabolic mirror 1, reflected by the plane mirror 3, and re-reflected again. The light is reflected by the object mirror 1, transmitted between the electrodes of the light source 4, and after being reflected by the parabolic mirror 1 for the fourth time, exits from the window 2 of the plane mirror 3 again and the front glass 12 and the UV / IR cut filter 17 To Penetrate. Since this retroreflected light is circularly polarized light, the following quarter-wave plate 18
Is converted into S-polarized light when transmitted through, and thus is transmitted through the WG polarizer 19. That is, if the transmittance and the reflectance of each optical element are 100%, all the light fluxes emitted from the light source 4 are adjusted to one polarization and the integrator optical system 1
Guided to 1.

As a result, the efficiency of linear polarization of the light beam emitted from the light source 4 is improved. Furthermore, almost all of the light flux emitted from the light source 4 and reflected by the parabolic mirror 1 can be made to enter the integrator optical system 11 through the window 2 as parallel light, and the utilization efficiency of the light flux in the integrator optical system 11 can be improved. Get higher Further, the outer size of the integrator optical system 11 can be reduced to the same size as the window 2.

In this embodiment, the integrator optical system 11 using the pair of fly-eye lenses 13 and 14 is used.
However, an integrator optical system using a lot integrator using columnar glass having a well-known structure may be used. In the integrator optical system using this lot integrator, a convex lens is arranged immediately after the WG polarizer 19 so that parallel light that has passed through the WG polarizer 19 can enter the lot integrator. The liquid crystal panel 16 whose cross-section of the lot integrator is to be irradiated
If the shape is similar to the shape of
Even if it is not so, it does not impair the essence of the present invention.

Next, a second embodiment of the present invention will be described with reference to FIG.
It will be described based on. The basic structure of this embodiment is shown in FIG.
The third embodiment is the same as the first embodiment shown in FIG. 2 and is different from the first embodiment in that the plane mirror 3 with the window 2 is arranged outside the front glass 12 and the fly-eye lens 14 in the latter stage. A polarization converter (which randomly randomizes light into one polarization by combining a polarization alignment prism array and a half-wave plate) between the cylindrical lens arrays constituting the convex lens)
The point 15a is disposed substantially in the middle between the fly-eye lens 14 and the liquid crystal panel 16 which is the irradiation target.

With this structure, even if the degree of polarization of the light beam passing through the WG polarizer 19 is about 90%, the polarization converter 20 can further improve the degree of polarization.

Even with such a configuration, the role operation of the quarter-wave plate 18 and the WG polarizer 19 is similar to that of the first embodiment described above.

FIG. 7 and FIG. 8 show the third embodiment of the present invention.
It will be described based on. The basic structure of the present invention is the first and second
The third embodiment is the same as the first embodiment, and the point different from the first and second embodiments is the position of the plane mirror 3a. Plane mirror 3
The a is formed of a member different from the front glass 12, and is disposed between the front glass 12 and the light source 4. That is, the plane mirror 3a is separated from the front glass 12 and is brought closer to the light source 4 side. The size and shape of the window 2 formed on the plane mirror 3a are the same as those in the first and second embodiments.

The light beam emitted from the light source 4 is made into substantially parallel light by the parabolic mirror 1, but generally includes a divergence angle of 5 to 10 °. According to the configuration of this embodiment, the plane mirror 3a recurs before the light is emitted from the light source 4 and its divergence increases, so that the light source image formed at the focal point F of the recursive light flux can be suppressed to a small value. As a result, the divergence angle after being reflected by the parabolic mirror 1 and made into parallel light again can be suppressed to a small value, so that it is possible to suppress a decrease in the utilization efficiency of the light flux in the integrator optical system 11. Also,
According to the configuration of the present embodiment, as shown by the chain double-dashed line (cuttable position) in the figure, it is possible to cut the part of the parabolic mirror 1 that is off the plane mirror 3a. The housing can be made thin. The same processing can be performed not only on the upper and lower sides but also on the left and right sides. Furthermore, the outside of the two-dot chain line on the upper, lower, left and right sides may be formed into a box shape instead of being cut, and the housing can be similarly thinned.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
And it demonstrates based on FIG. In the present embodiment, the plane mirror 3b is integrated with the fly-eye lens 13,
The other structure is the same as that of any of the first to third embodiments described above.

Further, the quarter-wave plate 18 and the WG polarizer 19
The outer shapes of and are matched with the size of the fly-eye lens 13 and the size of the window 2 of the plane mirror 3b.

Also in the present embodiment, it is possible to obtain the same actions and effects as those in the above-mentioned respective embodiments.

Next, a modified example of the shape of the window 2 in each of the above-described embodiments will be described with reference to FIG. In this case, as fly-eye lenses 13 and 14, 7 × 9 element lenses each having a width of 4 mm and a height of 3 mm are arranged (horizontal 4 × 7 = 28 mm, length 3 × 9 = 27 mm), and the window 2 The four corners are hidden one by one according to the shape (a)
And three hidden ones (b). This is a device for reducing the maximum value of the incident angle of the light flux entering the liquid crystal panel 16 to be illuminated and maintaining the illumination efficiency. The smaller the incident angle of the light flux entering the liquid crystal panel 16, the better the performance against contrast and color unevenness. The numerical values in parentheses in FIG. 11 indicate (x, y, l), that is, the x-coordinate, y-coordinate of the point, and the length 1 of the diagonal point-symmetric with respect to the origin.

Next, a fifth embodiment of the present invention will be described with reference to FIG.
It will be described based on 2. The illumination device according to the present embodiment uses the invention principle B shown in FIG. 2, and uses the parabolic mirror 1 as a reflector and the parabolic mirror 6 as a front mirror.

The focal length of this parabolic mirror 6 is equal to that of the parabolic mirror 1.
It is preferable that the range is 2 to 4 times the focal length F1 of the parabolic mirror 1 and the position of the focal point is aligned with the focal position of the parabolic mirror 1. Other than that, any of the first to fourth embodiments described above may be used. 1/4 wave plate 18 and WG polarizer 1 in this case
The roles and operations of 9 are the same.

However, since the front mirror with the window 2 is the parabolic mirror 6, it is reflected by the WG polarizer 19 and then returns, and then is reflected by the parabolic mirror 1 and passes through the electrodes of the light source 4. The light goes directly to the parabolic mirror 6, is reflected, then is reflected again by the parabolic mirror 1, passes through between the electrodes of the light source 4 again, and is reflected again by the parabolic mirror 1 again to become parallel light, and the window 2 1/4 through the
The light flux heading for the wave plate 18 and the WG polarizer 19, and after being reflected by the WG polarizer 19 and returning, are reflected by the parabolic mirror 1,
The light passes through the electrodes of the light source 4, is reflected again by the parabolic mirror 1, goes to the parabolic mirror 6, is reflected, and then passes through the electrodes of the light source 4 again, and is again reflected by the parabolic mirror 1. , A parallel light beam that passes through the window 2 and travels to the quarter-wave plate 18 and the light beam toward the WG polarizer 19, both of which have a higher number of reflections than in the above-described four embodiments. Once less. Therefore, the loss of the light flux due to reflection can be suppressed, and the light flux can be effectively used.

Next, a sixth embodiment of the present invention will be described with reference to FIG.
It will be described based on 3. The illumination device according to the present embodiment uses the invention principle C shown in FIG. 3, and uses an ellipsoidal mirror 7 as a reflector and a plane mirror 3 as a front mirror.

The front mirror 3 is arranged on the minor axis of the ellipsoidal mirror 7, and the WG polarizer 19 cut out with the same contour as the window 2 of the front mirror 3 is flush with the mirror surface of the front mirror 3. It is inset to do. Further, a quarter wave plate 18 is arranged immediately before the WG polarizer 19 so as to cover the entire plane mirror 3. In the range of the plane mirror 3, randomly polarized light enters the quarter wave plate 18 and is reflected by the mirror surface to be 1 /
After exiting the four-wave plate 18, it is still randomly polarized light,
The quarter wave plate 18 has no influence on the light beam reflected by the plane mirror 3. Of course, even if the quarter wave plate 18 is cut out to have the same contour as the window 2, the essence of the present invention is not impaired.

The light beam emitted from the light source 4 is reflected by the ellipsoidal mirror 7 toward the second focal point, and reaches the WG polarizer 19 via the quarter wavelength plate 18. Since this light flux is randomly polarized light, one polarized light (P polarized light) is transmitted and heads for the second focus. The other polarized light (S polarized light) is reflected and returned to the light source 4. Here, the light flux returned to the direction of the light source 4 is converted into circularly polarized light by passing through the quarter-wave plate 18, passes between the electrodes of the light source 4, is reflected by the ellipsoidal mirror 7, and is again 1 /. The circularly polarized state is kept until it reaches the four-wave plate 18. This circularly polarized light is converted into quarter wave plate 18
Is converted into P-polarized light when transmitted through the WG polarizer 19
And goes to the second focal point.

In this way, if the reflection efficiency of the ellipsoidal mirror 7 is 100%, it is possible to illuminate the liquid crystal panel 16 by converting all the luminous flux emitted from the light source 4 into one polarized light. Further, in reality, since the reflection efficiency of the ellipsoidal mirror 7 is 90% or more, the polarized light is more efficiently reflected in this embodiment, which has a smaller number of reflections than the above-described embodiment using the parabolic mirror 1 as a reflector. Can be obtained.

Next, a seventh embodiment of the present invention will be described with reference to FIG.
4 will be described. The illumination device according to the present embodiment uses the invention principle D shown in FIG. 4, and uses an ellipsoidal mirror 7 as a reflector and a spherical mirror (convex mirror) 8 as a front mirror. The spherical mirror 8 has a spherical focal point at the second focal position of the ellipsoidal mirror 7. In this case, the quarter-wave plate 18a and the WG polarizer 19a need to have a spherical shape with the second focus position of the ellipsoidal mirror 7 as the spherical center, but the installation position is at the rear stage of the spherical mirror 8 having the window 2. Can be side.
Further, an aspherical concave lens 21 for collimating the light flux that has passed through the window 2 of the spherical mirror 8 is arranged at the rear stage of the front glass 12.

The roles and operations of the quarter-wave plate 18a and the WG polarizer 19a are the same as those in each of the above-described embodiments, but between the ellipsoidal mirror 7 and the spherical mirror 8, the first and the second mirrors are provided. Two
The behavior is similar to the relationship between the parabolic mirror 1 and the plane mirror 3 described in the embodiment (FIGS. 5 and 6).

Next, an eighth embodiment of the present invention will be described with reference to FIG.
It will be described based on 5. The basic structure of this embodiment is the same as that of the seventh embodiment (FIG. 14), except that
The quarter wave plate 18 and the WG polarizer 19 are formed in a flat plate shape and are arranged between the aspherical concave lens 21 and the fly-eye lens 13.

The roles and operations of the quarter-wave plate 18 and the WG polarizer 19 are the same as those in the above-described embodiments, and the WG
When the other polarized light (S polarized light) reflected by the polarizer 19 is returned to the ellipsoidal mirror 7 and returned to the WG polarizer 19 again, it is converted into one polarized light (P polarized light). The light passes through the WG polarizer 19 as it is.

Next, a ninth embodiment of the present invention will be described with reference to FIG.
6 will be described. This embodiment is based on FIG.
Is an example in which the illuminating device is applied to a liquid crystal projector.

Fly-eye lens 14 and superimposing lens 15a
A total reflection mirror 22 for changing the traveling direction of the light flux by 90 ° is disposed between and.

The polarizer 2 is provided on the rear side of the superimposing lens 15a.
3, color selection wavelength plate 24, PBS (polarization beam splitter) 25, dichroic prism 26, glass block 27, color selection wavelength plate 28, polarizer 29, projection lens 3
0 etc. are arranged.

The polarizer 23 disposed on the rear side of the superimposing lens 15a is for improving the degree of polarization of the light beam (P-polarized light) that passes through the superimposing lens 15a. An absorption type polarizer may be used when it is relatively small.

The color selection wavelength plate 24 converts the polarization of only the green band (converts it into S-polarized light), and the light flux that has passed through the color selection wavelength plate 24 and is incident on the PBS 25 is S-polarized light. A certain green color is transmitted to the glass block 27 side as it is, and red and blue which are P-polarized light are reflected to the dichroic prism 26 side. The light fluxes of red and blue reflected by the PBS 25 are separated into red and blue by the dichroic prism 26, and the liquid crystal panels 16R and 16 are respectively separated.
Modulated by B. The green luminous flux transmitted through the PBS 25 is also modulated by the liquid crystal panel 16G.

In each of the liquid crystal panels 16R, 16B and 16G, the luminous flux arriving by the electric signal provided from the image information control section (not shown) is modulated (the ON signal converts the polarization to the opposite, and the OFF signal remains the polarization). To reflect). Since the modulated light beam has its polarization changed in reverse, PBS25
Returning to, the red and blue are transmitted through the PBS 25, and the green is reflected by the PBS 25 and guided to the projection lens 30 side.
Since there is a color selection wavelength plate 28 at the exit of the PBS 25, the polarization of green is changed to S-polarized light again, and red and blue are polarized light (S-polarized light) as they are, so all visible light is S-polarized light. Becomes By passing such S-polarized light through the polarizer 29, excess flare light is cut and the contrast is improved, and this modulated light flux is projected onto the projection lens 3
It is projected on the screen 31 via 0.

[0083]

According to the illumination device of the first aspect of the invention, the luminous flux emitted from the light source is reflected by the reflector, or after being reflected by the front mirror and the reflector, the light beam passes through the window of the front mirror. Since the light is transmitted and emitted toward the integrator optical system, the utilization efficiency of the light flux in the integrator optical system is increased. Also, the external size of the input part of the integrator optical system can be made the same as the size of the window,
It is possible to reduce the size of the integrator optical system. Further, by providing the quarter-wave plate and the wire grid polarizer, it is possible to enhance the efficiency of linear polarization for aligning the light flux emitted from the light source and entering the integrator optical system into one linear polarization.

According to a second aspect of the invention, in the illumination device according to the first aspect, the integrator optical system is
Since the light beams divided into a plurality of optical axes are superposed on the illumination target, the action and effect of the invention according to claim 1 can be obtained even when the integrator optical system of this type is used.

According to a third aspect of the invention, in the illumination device according to the first aspect, the integrator optical system is
Since it is of the lot type, even when the integrator optical system of such a type is used, the action and effect of the invention described in claim 1 can be obtained.

According to a fourth aspect of the invention, in the illumination device according to any one of the first to third aspects, the reflector is a parabolic mirror and the front mirror is a plane mirror. The parallelism of the luminous flux can be increased, and the utilization efficiency of the luminous flux in the integrator optical system can be sufficiently enhanced.

According to a fifth aspect of the present invention, in the illumination device according to any one of the first to third aspects, the reflector is a parabolic mirror, and the front mirror shares a focus with the reflector. Since it is an object mirror, the parallelism of the light beam passing through the window can be increased, and the utilization efficiency of the light beam in the integrator optical system can be sufficiently increased.
Further, the light flux first reflected by the parabolic mirror, which is the front mirror, after being emitted from the light source can also be transmitted through the window as parallel light, and the utilization efficiency of the light flux in the integrator optical system is further enhanced.

According to a sixth aspect of the present invention, in the illumination device according to any one of the first to third aspects, the reflector is an elliptical mirror, and the front mirror is on a minor axis of the elliptical mirror. Since the plane mirror is arranged, the light beam emitted from the light source can be efficiently focused on the second focal point of the ellipsoidal mirror, and the light beam is collimated by a collimator lens or the like, so that the integrator optical system The utilization efficiency of the light flux can be sufficiently increased.

According to the invention described in claim 7, in the illumination device according to any one of claims 1 to 3, the reflector is an ellipsoidal mirror, and the front mirror is a second focal point of the ellipsoidal mirror. Since it is a spherical mirror having a spherical center, the light beam emitted from the light source can be efficiently focused on the second focal point of the ellipsoidal mirror, and the light beam is collimated by a collimator lens or the like to obtain an integrator optical system. It is possible to sufficiently enhance the utilization efficiency of the light flux in the.

According to the liquid crystal projector of the eighth aspect of the invention, since the liquid crystal panel is illuminated by using the illuminating device according to any one of the first to seventh aspects of the invention, the illumination having a high luminous flux utilization efficiency as a whole. The liquid crystal panel can be illuminated underneath, and it can be projected on the screen by a projection lens having a small aperture, and the overall size of the liquid crystal projector can be reduced.

[Brief description of drawings]

FIG. 1 is a principle diagram illustrating an invention principle A of the present invention.

FIG. 2 is a principle diagram illustrating an invention principle B of the present invention.

FIG. 3 is a principle diagram illustrating an inventive principle C of the present invention.

FIG. 4 is a principle diagram illustrating an inventive principle D of the present invention.

FIG. 5 is an optical system configuration diagram showing the illumination device according to the first embodiment of the present invention.

FIG. 6 is an optical system configuration diagram showing an illumination device according to a second embodiment of the present invention.

FIG. 7 is a cross-sectional structural view in the vicinity of a reflector showing a main part of a lighting device according to a third embodiment of the present invention.

FIG. 8 is a front view of the reflector.

FIG. 9 is a cross-sectional structural view near a reflector showing a main part of a lighting device according to a fourth embodiment of the present invention.

FIG. 10 is its front surface.

FIG. 11 is a front view showing a modification of the window shape.

FIG. 12 is an optical system configuration diagram showing an illumination device according to a fifth embodiment of the present invention.

FIG. 13 is an optical system configuration diagram showing an illumination device according to a sixth embodiment of the present invention.

FIG. 14 is an optical system configuration diagram showing an illumination device according to a seventh embodiment of the present invention.

FIG. 15 is an optical system configuration diagram showing an illumination device according to an eighth embodiment of the present invention.

FIG. 16 is an optical system configuration diagram showing a liquid crystal projector of a ninth embodiment of the present invention.

FIG. 17 is an optical system configuration diagram showing a conventional illumination device.

FIG. 18 is an optical system configuration diagram showing another conventional illumination device.

FIG. 19 is a diagram illustrating the principle of a reflector of a conventional lighting device.

FIG. 20 is a principle explanatory diagram of a reflector of another conventional lighting device.

[Explanation of symbols]

1 reflector, parabolic mirror 2 windows 3, 3a, 3b Front mirror, plane mirror 4 light sources 6 Front mirror, parabolic mirror 7 Reflector, elliptical mirror 8 Front mirror, spherical mirror 11 Integrator optical system 16R, 16B, 16G liquid crystal panel 18, 18a 1/4 wave plate 19, 19a Wire grid polarizer 30 projection lens 31 screen

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 5/74 H04N 5/74 AF term (reference) 2H088 EA12 HA13 HA17 HA18 HA21 HA24 HA28 MA20 2H091 FA05X FA08X FA08Z FA11X FA11Z FA14Z FA26X FA41Z LA11 MA07 2K103 AA05 AB04 BA05 BA07 BA09 BB02 BC03 BC12 BC16 BC17 BC26 CA24 5C058 BA23 EA01 EA02 EA11 EA13 EA14 EA26 EA42 EA51

Claims (8)

[Claims] 1. A light source is provided near the focal point of the reflector,
In an illuminating device that emits a light flux emitted from this light source and reflected by the reflector toward an integrator optical system, the reflection surface is arranged so as to be orthogonal to the optical axis of the reflector and facing the reflector, and is arranged in the central portion. A front mirror having a translucent window having a size substantially the same as the external size of the input section of the integrator optical system, and a front direction of the integrator optical system in a traveling direction of a light beam emitted from the window. An illuminating device comprising: a quarter-wave plate and a wire grid polarizer, which are arranged in order. 2. The illumination device according to claim 1, wherein the integrator optical system is of a type in which light beams divided into a plurality of optical axes are superimposed on an illumination target. 3. The illumination device according to claim 1, wherein the integrator optical system is of a lot type. 4. The lighting device according to claim 1, wherein the reflector is a parabolic mirror, and the front mirror is a plane mirror. 5. The illumination device according to claim 1, wherein the reflector is a parabolic mirror, and the front mirror is a parabolic mirror that shares a focal point with the reflector. 6. The illumination device according to claim 1, wherein the reflector is an ellipsoidal mirror, and the front mirror is a plane mirror arranged on a minor axis of the ellipsoidal mirror. 7. The illuminating device according to claim 1, wherein the reflector is an elliptical mirror, and the front mirror is a spherical mirror having a second focus of the elliptical mirror as a spherical center. 8. The at least one liquid crystal panel on which an image to be projected by an image information control unit is formed, the illumination device according to claim 1, which illuminates the liquid crystal panel as an illumination target. A liquid crystal projector having a projection lens for projecting an image of a liquid crystal panel onto a screen.