JP2004191796A - Illumination optical system, projector equipped with the same, light source device used for the same and light emitting tube used for light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize the omission and the simplification of an optical element constituting an illumination optical system. <P>SOLUTION: A polarized light generating part has a nearly rectangular light incident surface 132 whose size in a direction (y) is smaller than size in a direction (x), so that the nearly parallel flux of rays made incident on the surface 132 are separated to the flux of rays of two kinds of polarized light whose polarization directions are orthogonal to each other. By arranging the flux of rays of two kinds of polarized light in the direction (y), the cross sectional shape of the emitted flux of rays is enlarged in the direction (y) while keeping the flux of rays nearly parallel. By arranging the polarization direction of either of the flux of rays of two kinds of polarized light to be uniform to the polarization direction of the other, the flux of rays of nearly one kind of polarized light are generated. The reflector 114 of the light source device 110 reflects light emitted from the light emission part 112c of the light emitting tube 112 arranged at the focal position of a reflection concave surface. In the light emitting tube, a reflection surface 112m is formed at a part on the tubular surface of the light emitting part 112c so that the cross sectional shape of the flux of rays emitted from the light source device may be the shape near to the light incident surface of the polarized light generating part. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an illumination optical system that illuminates a light modulation device included in a projector, and more particularly to a technique for efficiently emitting polarized light having a specific polarization direction.
[0002]
[Prior art]
In a projector, light emitted from an illumination optical system is modulated according to image information (image signal) using a light modulator (also called a light valve) using a liquid crystal panel or the like, and the modulated light is projected on a screen. Image display is realized by projection.
[0003]
A light valve using a liquid crystal panel (hereinafter, also referred to as a “liquid crystal light valve”) usually includes a polarizing plate on an incident side and an exit side of the liquid crystal panel, and a specific polarized light is used. For this reason, as the illumination optical system, the light illuminating the liquid crystal panel is used efficiently, and the light emitted from the lamp without bias (hereinafter, simply referred to as “non-polarized light”) is used in the liquid crystal panel. One having a polarization generating optical system for converting into polarized light having a possible polarization direction is used. Further, as a polarization generation optical system, one that converts non-polarized light emitted from a lamp into polarized light more efficiently is used (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-2002-6260
[Patent Document 2]
JP 2000-292740 A
[Patent Document 3]
JP-A-5-323236
[0005]
FIG. 6 is an explanatory diagram showing a conventional illumination optical system 900. The illumination optical system 900 includes a light source device 920, a polarization generation optical system 930, first and second lens arrays 970 and 980, and a superimposing lens 990. Light emitted from the illumination optical system 900 is emitted with the system optical axis Lax as a central axis. In FIG. 6, the illumination area LA illuminated by the illumination optical system 900 corresponds to the light modulator of the projector.
[0006]
The light source device 920 has a function of emitting a substantially parallel light beam. The light source device 920 includes a lamp (arc tube) 922, a reflector 924 having a spheroidal concave surface, and a parallelizing lens 926. The light emitted from the lamp 922 is reflected by the reflector 924, and the reflected light is converted by the collimating lens 926 into substantially parallel light.
[0007]
As the lamp 922, a metal halide lamp, a high-pressure mercury lamp, or the like is used. As the collimating lens 926, an aspherical lens is used. Specifically, an aspherical lens having a concave surface in the shape of a rotational hyperboloid on the incident surface and a flat surface on the exit surface is used.
[0008]
The polarization generating optical system 930 includes two light beam expanding units 940 and 950 and a λ / 2 phase difference plate 960. The polarization generating optical system 930 has a function of enlarging the cross-sectional shape of the incident light beam to approximately four times and emitting the light beam. That is, the first light beam expanding unit 940 has a function of expanding the cross-sectional shape of the incident light beam almost twice in the x direction. Has the function of enlarging the cross-sectional shape almost twice in the y direction. The polarization generating optical system 930 has a function of generating almost one type of polarized light having a predetermined polarization direction from the incident non-polarized light.
[0009]
FIG. 7 is an enlarged perspective view showing the polarization generating optical system 930 of FIG. 6 in an enlarged manner. As shown in the figure, the first and second light beam bundle enlargers 940 and 950 are configured by combining a plurality of substantially columnar light-transmitting members (referred to as “right-angle prisms”) each having a substantially right-angled triangular bottom surface. ing. In addition, as the translucent member, for example, glass is used.
[0010]
The first light beam expanding unit 940 includes three light transmitting members 941 to 943. The first translucent member 941 is joined to the second and third translucent members 942 and 943. A semi-transparent mirror film (beam splitter) 940a is formed at the interface between the first and second translucent members 941 and 942, and the third translucent member 943 is substantially parallel to the semi-transparent mirror film 940a. Is formed with a reflection film 940b. Here, the semi-transparent mirror film is a thin film that transmits a part of the incident light amount and reflects the other part, and is formed of a metal film or a dielectric multilayer film. The semi-transparent mirror film 940a of this example has an optical characteristic of transmitting approximately 50% of the incident light amount and reflecting approximately 50%, and functions as a so-called half mirror. The reflection film 940b is a thin film that reflects most of the amount of incident light, and is formed of a dielectric multilayer film or a metal film.
[0011]
Light that has entered the first light-transmitting member 941 is split into two lights by the semi-transparent mirror film 940a. The light transmitted through the semi-transparent mirror film 940a is emitted through the second light-transmitting member 942. On the other hand, the light reflected by the semi-transparent mirror film 940a enters the third light-transmitting member 943, is reflected by the reflection film 940b, and is emitted. That is, the light incident on the first light transmitting member 941 is separated, and the separated light is emitted from the second and third light transmitting members 942 and 943. As a result, the first light beam expanding unit 940 enlarges the cross-sectional shape of the incident light beam almost twice in the x direction.
[0012]
The second light beam expanding unit 950 includes six light transmitting members 951 to 956. The first light-transmitting member 951 is joined to the second and third light-transmitting members 952, 953. A polarization separation film (deflection beam splitter) 950a is formed at the interface between the first and second light-transmitting members 951 and 952, and the third light-transmissive member 953 is substantially the same as the polarization separation film 950a. The reflection film 950b is formed in parallel. Here, the polarization separation film 950a is a thin film that separates incident non-polarized light (s + p) into p-polarized light and s-polarized light, and is formed of a dielectric multilayer film. The separated p-polarized light and s-polarized light have a light amount of approximately 50% of the incident light amount.
[0013]
The unpolarized light (s + p) incident on the first translucent member 951 is separated into p-polarized light and s-polarized light by the polarization separation film 950a. The p-polarized light transmitted through the polarization separation film 950a passes through the second light-transmitting member 952 and is emitted. On the other hand, the s-polarized light reflected by the polarization separation film 950a enters the third light-transmitting member 953, is reflected by the reflection film 950b, and is emitted. That is, the non-polarized light (s + p) incident on the first light-transmitting member 951 is separated into p-polarized light and s-polarized light, and the second light-transmitting member 952 and the third light-transmitting light, respectively. It is ejected from the member 953.
[0014]
The fourth to sixth translucent members 954 to 956 are the same as the first to third translucent members 951 to 953. That is, the non-polarized light (s + p) incident on the fourth light-transmitting member 954 is separated into p-polarized light and s-polarized light, and the fifth light-transmitting member 95 5 and the sixth light-transmitting light, respectively. It is ejected from the member 956. Accordingly, the second light beam expanding unit 950 enlarges the cross-sectional shape of the incident light beam almost twice in the y direction.
[0015]
The λ / 2 phase difference plate 960 has a function as a polarization conversion element that converts incident linearly polarized light into linearly polarized light whose polarization direction is orthogonal. In the present example, as shown in FIG. 3, the λ / 2 phase difference plate 960 is provided on the exit surfaces of the second and fifth translucent members 952 and 955 of the second light beam expanding unit 950. I have. The p-polarized light emitted from the second and fifth translucent members 952 and 955 is converted into s-polarized light by the λ / 2 retardation plate 960 and emitted. Note that s-polarized light is emitted from the third and sixth translucent members 953, 956. Thus, the unpolarized light (s + p) incident on the polarization generating optical system 930 is converted into s-polarized light and emitted.
[0016]
If a λ / 2 retardation plate is disposed on the exit surfaces of the third and sixth translucent members 953 and 956 from which the s-polarized light is emitted, the non-polarized light incident on the polarization generating optical system 930 can be converted into p-polarized light. It can be converted into polarized light and emitted.
[0017]
As described above, the polarization generating optical system 930 converts the incident non-polarized light into the s-polarized light, and enlarges the cross-sectional shape of the incident light beam almost four times. The light emitted from the polarization generating optical system 130 enters the first lens array 970 (FIG. 6).
[0018]
The first lens array 970 has a plurality of small lenses 972 arranged in a matrix. Each small lens 972 is a plano-convex lens, and its external shape when viewed from the z direction is set to be similar to the illumination area LA (light modulation device). The first lens array 970 divides the substantially parallel s-polarized light beam emitted from the polarization generating optical system 930 into a plurality of s-polarized partial light beams and emits them.
[0019]
The second lens array 980 has a plurality of small lenses 982 arranged in a matrix, and the same as the first lens array 970 is used. The second lens array 980 and the superimposing lens 990 have a function of forming an image of each small lens 972 of the first lens array 970 on the illumination area LA.
[0020]
The superimposing lens 990 has a function of superimposing a plurality of s-polarized partial light beams having the same polarization direction on the illumination area LA as shown in FIG. At this time, the intensity distribution of the light illuminating the illumination area LA is substantially uniform.
[0021]
As described above, in the conventional illumination optical system 900, the non-polarized light emitted from the light source device 920 is efficiently converted into polarized light by causing the substantially parallel non-polarized light to enter the polarization generation optical system 930. can do.
[0022]
The size of the substantially parallel light beam emitted from the light source device 920 can be considerably reduced by adjusting the position of the collimating lens 926. Accordingly, the size of the polarization generation optical system 930 can be reduced, and as a result, the size of the illumination optical system 900 can be reduced.
[0023]
In addition, when the light modulation device serving as the illumination region uses, for example, a liquid crystal panel, its optical characteristics greatly depend on the angle of incident light (called “swallow angle”). In the conventional illumination optical system 900, the ratio between the size in the x direction and the size in the y direction of the light beam emitted from the polarization generation optical system 930 is set to be approximately 1: 1. As a result, the swallow angles θx and θy in the x direction and the y direction of the illumination area LA are substantially the same. Therefore, if the projector illuminates the light modulation device using such an illumination optical system 900, an image without color unevenness or brightness unevenness can be projected.
[0024]
[Problems to be solved by the invention]
However, in the above-described conventional illumination optical system 900, the polarization generating optical system 930 is configured by the two light beam expanding units 940 and 950. Further, the first light beam expanding unit 940 is configured by combining three light transmitting members called right angle prisms, and the second light beam expanding unit 950 is configured by combining six light transmitting members. That is, the polarization generating optical system 930 is configured by many translucent members.
[0025]
In addition, as described above, by adjusting the position of the collimating lens 926 to reduce the size of the light beam emitted from the light source device 920, the two light beam expanding units 940 and 950 serve as illumination regions. It is possible to reduce the size to the same size as the modulator. However, a right-angle prism having a size comparable to that of a light modulator is relatively expensive.
[0026]
Therefore, in order to further reduce the size and cost of the projector, the optical elements constituting the conventional illumination optical system 900 are omitted and simplified, and more specifically, the polarized light constituting the conventional illumination optical system 900. It is desired that the generation optical system 930 be omitted or simplified.
[0027]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems in the related art, and it is possible to omit and simplify the optical elements constituting the illumination optical system as compared with the conventional illumination optical system. It aims to provide technology.
[0028]
[Means for Solving the Problems and Their Functions and Effects]
In order to solve at least a part of the problems described above, a first apparatus of the present invention is an illumination optical system,
A light source device for emitting condensed light,
A lens for collimating the condensed light,
When two directions perpendicular to the center axis of the light beam emitted from the light source device and orthogonal to each other are defined as first and second directions, the size in the second direction is equal to the size in the first direction. It has a substantially rectangular light incident surface that is shorter than the light incident surface, and separates substantially parallel light beams emitted from the lens and incident on the light incident surface into two types of polarized light beams whose polarization directions are orthogonal to each other. By arranging the separated two types of polarized light beams along the second direction, the cross-sectional shape of the emitted light beam is expanded while being substantially parallel along the second direction, and separated. A polarization generating unit that generates substantially one type of polarized light beam having a predetermined polarization direction by aligning one polarization direction of the two types of polarized light beams with the other.
A lens array for dividing the substantially parallel polarized light beam emitted from the polarization generating unit into a plurality of partially polarized light beams,
A superimposing optical system for superimposing the plurality of partially polarized light beams on a predetermined illumination area,
The light source device,
An arc tube,
A reflector having a spheroidal reflective concave surface, and reflecting light emitted from a light emitting unit of the arc tube arranged at a focal position of the reflective concave surface,
A reflection surface is formed on a part of the light emitting unit on a tube surface of the light emitting tube such that a cross-sectional shape of a light beam emitted from the light source device has a shape close to the light incident surface. It is characterized by.
[0029]
The polarization generator of the illumination optical system converts a substantially parallel light beam incident from a substantially rectangular incident surface whose size in the second direction is shorter than the size in the first direction into two light beams whose polarization directions are orthogonal to each other. By separating the separated two types of polarized light beams along the second direction, the cross-sectional shape of the emitted light beam is substantially parallel along the second direction. By enlarging as it is and by aligning one polarization direction of the separated two types of polarized light beams with the other, a substantially one type of polarized light beam having a predetermined polarization direction is generated. As described above, when a substantially parallel light beam is incident on the polarization generation unit, the light emitted from the light source device can be efficiently processed by the polarization generation unit. Almost one type of polarized light can be emitted efficiently.
[0030]
Further, the light source device of the illumination optical system emits a light beam having a cross-sectional shape close to the shape of the incident surface of the polarization generating section. As described above, when the light beam emitted from the light source device has a cross-sectional shape close to the shape of the incident surface of the polarization generation unit, the light emitted from the light source device is efficiently incident on the polarization generation unit. Since the light can be incident on the surface and processed, almost one type of polarized light can be efficiently emitted similarly to the conventional illumination optical system.
[0031]
Further, the polarization generating section of the illumination optical system sets the cross-sectional shape of the light beam emitted from the light source device to a shape close to the incident surface of the polarization generating section, thereby changing the cross-sectional shape of the emitted light beam in the second direction. Only to expand. Accordingly, it is possible to omit and simplify the polarization generating section, and it is possible to omit and simplify the optical elements constituting the illumination optical system.
[0032]
Here, the reflection surface is located on a half tube surface that is perpendicular to the central axis of the light beam emitted from the light source device and includes a center of the light emitting unit and is closer to a traveling direction side of the light beam. In addition, of the divided regions obtained by dividing the half tube surface into four regions, the divided regions are not formed in the two divided regions facing each other along the first direction, and are not formed along the second direction. Preferably, it is formed in the other two opposing divided regions.
[0033]
With this configuration, the cross-sectional shape of the light beam emitted from the light source device can be made close to the light incident surface.
[0034]
Further, the reflector may be configured such that, assuming that light is emitted from the two divided regions where the reflection surface is formed, the reflection concave surface required to reflect light that can be emitted from the two divided regions is provided. Preferably, the area has been deleted.
[0035]
In this case, the size of the light source device of the illumination optical system can be reduced, and as a result, the size of the illumination optical system can be reduced.
[0036]
In the above-mentioned illumination optical system, the polarization generator may have a ratio of the size of the light incident surface in the first direction to the size of the second direction of approximately 2: 1, and The substantially parallel light beam incident from the light incident surface is converted into the second light beam so that the ratio of the size of the cross-sectional shape of the bundle in the first direction to the size in the second direction is approximately 1: 1. It is also preferable to double the size in the direction.
[0037]
If this illumination optical system is applied to a projector to illuminate a light modulation device such as a liquid crystal light valve, it is possible to reduce unevenness in color and brightness in an image projected and displayed.
[0038]
In the above illumination optical system,
The polarization generator,
Having the light incident surface, separating the substantially parallel light beams incident from the light incident surface into two types of polarized light beams orthogonal to each other along the second direction and emitting the light beams while being substantially parallel; A polarizing beam splitter that emits a polarized light beam whose cross-sectional shape is enlarged along the second direction;
A phase difference plate for aligning one polarization direction of the two types of polarized light beams emitted from the polarization beam splitter with the other polarization direction,
May be provided.
[0039]
With this configuration, the illumination optical system can expand the light beam in the second direction while keeping the light beam substantially parallel, and can efficiently emit almost one type of polarized light.
[0040]
A second device of the present invention is a projector,
An illumination optical system according to any of the above,
A light modulation device that modulates light from the illumination optical system according to image information,
A projection optical system that projects modulated light obtained by the light modulation device,
It is characterized by having.
[0041]
Since this projector includes the above-described illumination optical system, it is possible to efficiently emit almost one type of polarized light in the illumination optical system. It is possible to omit and simplify the optical elements constituting the illumination optical system. This makes it possible to improve the brightness of the image projected and displayed by the projector. Further, it is possible to omit and simplify the optical elements constituting the projector, and it is possible to reduce the size of the projector.
[0042]
A third device of the present invention is a light source device,
An arc tube,
A reflector having a spheroidal reflective concave surface, and reflecting light emitted from a light emitting unit of the arc tube arranged at a focal position of the reflective concave surface,
The arc tube has a cross section of a light beam emitted from the light source device when two directions perpendicular to a central axis of the light beam emitted from the light source device and orthogonal to each other are defined as first and second directions. A reflection surface is formed on a part of the light emitting unit on the tube surface so that the shape is smaller in the second direction than in the first direction.
[0043]
When this light source device is applied to the above-mentioned illumination optical system, almost one type of polarized light can be efficiently emitted similarly to the conventional illumination optical system, and the optical elements constituting the illumination optical system can be efficiently emitted. Omission and simplification can be achieved, and downsizing of the illumination optical system can be achieved.
[0044]
A fourth device of the present invention is an arc tube,
One half of the light-emitting unit, which is divided by a plane including the center of the light-emitting unit that emits light perpendicular to a predetermined central axis, on one half of the light-emitting unit, A reflection surface is not formed in two opposing divisional regions of the divided regions, and a reflection surface is formed in the other two opposing divisional regions.
[0045]
If this arc tube is applied to the light source device, the light beam emitted from the light source device has a cross-sectional shape in the second direction that is smaller in the second direction than in the first direction. The shape can be crushed along.
[0046]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in the following order based on examples.
A. projector:
B. Illumination optics:
C. Light source device:
D. Modification:
[0047]
A. projector:
FIG. 1 is a schematic configuration diagram illustrating an example of a projector to which the present invention has been applied. In the following description, three directions orthogonal to each other will be referred to as x direction (horizontal direction), y direction (vertical direction), and z direction (direction parallel to the system optical axis) for convenience.
[0048]
The projector 1000 includes an illumination optical system 100, a color light separation optical system 200, three liquid crystal light valves (light modulation devices) 300R, 300G, and 300B, a cross dichroic prism (photosynthesis optical system) 400, and a projection lens (projection lens). (Optical system) 500.
[0049]
The illumination optical system 100 emits one type of linearly polarized light having substantially uniform polarization directions. The light emitted from the illumination optical system 100 is separated into three color lights of red (R), green (G), and blue (B) in the color light separation optical system 200. The separated color lights illuminate the liquid crystal light valves 300R, 300G, 300B corresponding to each color. The illumination optical system 100 will be further described later.
[0050]
The color light separation optical system 200 includes two dichroic mirrors 220 and 240, two reflection mirrors 210 and 230, and a relay optical system 250. Light emitted from the illumination optical system 100 is reflected by the first reflection mirror 210 and is incident on the first dichroic mirror 220. The reflection mirror 210 can be omitted by arranging the illumination optical system 100 by rotating it 90 degrees clockwise.
[0051]
The color light separation optical system 200 converts the light beam emitted from the illumination optical system 100 by the two dichroic mirrors 220 and 240 from a first wavelength region corresponding to blue (about 435 nm to about 500 nm) and a first wavelength region. Light in a wavelength region including a short wavelength region (hereinafter, referred to as a “wavelength region equal to or less than the first wavelength region”), light in a second wavelength region corresponding to green (about 500 nm to about 590 nm), and red ( It has a function as a wavelength separation optical system for separating light into a third wavelength region corresponding to about 590 nm to about 700 nm). Note that light in a wavelength region equal to or less than the first wavelength region is limited to light (blue light) in a first wavelength region corresponding to blue by an optical filter 290 provided on a light exit surface of a field lens 280 described later. . Here, description will be made on the assumption that light in a wavelength region equal to or less than the first wavelength region is also blue light.
[0052]
The first dichroic mirror 220 reflects blue light and transmits green light components and red light components on a longer wavelength side than blue light. The blue light (B) reflected by the first dichroic mirror 220 is further reflected by the reflection mirror 230 toward the cross dichroic prism 400, and is formed on the light exit surface of the field lens 280 and the field lens 280. The light is incident on the light incident surface of the liquid crystal light valve 300B for blue light via the filter 290. The field lens 280 has a function of converting a light beam emitted from the illumination optical system 100 such that respective central light beams (principal light beams) are substantially parallel to each other. The same applies to the field lenses 270 and 260 provided in front of the other liquid crystal light valves 300G and 300R.
[0053]
Of the green light (G) and the red light (R) transmitted through the first dichroic mirror 220, the green light is reflected by the second dichroic mirror 240, and passes through the field lens 270 to a liquid crystal light valve for green light. The light is applied to the light incident surface of 300G. On the other hand, the red light passes through the second dichroic mirror 240 and passes through a relay optical system 250 having an entrance lens 252, a relay lens 256, an exit lens (field lens) 260, and reflection mirrors 254 and 258. The light is incident on the light incident surface of the liquid crystal light valve 300R for red light. The reason why the relay optical system 250 is used for red light is to prevent a reduction in light use efficiency because the path of red light is longer than the paths of other color lights. That is, this is for transmitting the image of the light incident on the incident side lens 252 to the exit side lens 260 as it is. Each of the two dichroic mirrors 220 and 240 is formed by coating a dielectric multilayer film corresponding to a transparent plate such as a glass plate.
[0054]
Each color light separated by the color light separation optical system 200 is applied to the light incident surface of the corresponding liquid crystal light valve 300R, 300G, 300B for each color light. Each of the liquid crystal light valves 300R, 300G, and 300B includes a light-transmitting liquid crystal panel and polarizing plates disposed on the light incident surface side and the light emission surface side. The polarizing plate arranged on the light incident surface side of the liquid crystal panel is for further increasing the degree of polarization of the illumination light, and the polarization direction of the linearly polarized light emitted from the illumination optical system 100 is changed by the polarization plate. It is arranged to be in the transmission axis direction. By doing so, the purity (degree of polarization) of the linearly polarized light included in the illumination light emitted from the illumination optical system 100 can be further increased. When the degree of polarization of the illumination light emitted from the illumination optical system 100 is extremely high, the polarizing plate disposed on the light incident surface side may be omitted.
[0055]
In addition, a driving unit (not shown) for supplying image information to and driving the liquid crystal panel is connected to each of the liquid crystal light valves 300R, 300G, and 300B. The modulated light fluxes modulated according to the image information in the liquid crystal light valves 300R, 300G, and 300B are emitted as image light representing images of each color.
[0056]
The three colors of image light (modulated light beam) emitted from the liquid crystal light valves 300R, 300G, and 300B are incident on the cross dichroic prism 400. The cross dichroic prism 400 has a function as a light combining optical system for combining three color image lights. In the cross dichroic prism 400, a dielectric multilayer film 410R that reflects red light and a dielectric multilayer film 410B that reflects blue light are formed in an approximately X-shape at the interface between the four right-angle prisms. The three colors of image light are combined by these dielectric multilayer films and emitted toward the projection lens 500.
[0057]
The projection lens 500 projects the combined light emitted from the cross dichroic prism 400 and displays a color image on a screen (not shown). Note that a telecentric lens can be used as the projection lens 500.
[0058]
Note that the projector 1000 of the present embodiment is characterized by the illumination optical system 100 described below.
[0059]
B. Illumination optics:
FIG. 2 is an explanatory diagram showing the illumination optical system 100 of FIG. 1 in an enlarged manner. The illumination optical system 100 includes a light source device 110, a collimating lens 120, a polarization generating optical system 130, first and second lens arrays 170 and 180, and a superimposing lens 190. The light beam emitted from the illumination optical system 100 is emitted with the system optical axis Lax as a central axis. In FIG. 2, the illumination area LA illuminated by the illumination optical system 100 corresponds to the liquid crystal light valves 300R, 300G, and 300B of the projector 1000 (FIG. 1).
[0060]
The light source device 110 includes a lamp 112 and a reflector 114 that reflects radiation emitted from the lamp 112. The light source device 110 has a function of emitting condensed light toward the collimating lens 120 as described later. The light beam emitted from the light source device 110 is emitted with the light source optical axis 110ax as the central axis.
[0061]
The condensed light emitted from the light source device 110 is converted by the collimating lens 120 into substantially parallel light. In the present embodiment, an aspheric lens is used as the collimating lens 120. Specifically, a non-spherical lens having a hyperboloid-shaped or spheroid-shaped concave surface on the incident surface and a flat surface on the exit surface is used. A spherical lens is used. The light beam collimated by the collimating lens 120 is emitted toward the incident surface 132 of the polarization generating optical system 130.
[0062]
The polarization generation optical system 130 includes a polarization beam splitter 150 and a λ / 2 retardation plate 160. The polarization generating optical system 130 has a function of expanding a light beam incident from the incident surface 132 into a light beam approximately twice as large in the y direction and emitting the light beam from the emission surface 134. Further, the polarization generating optical system 130 has a function of generating almost one kind of polarized light beam having a predetermined polarization direction from an incident light beam (non-polarized light beam) without bias.
[0063]
FIG. 3 is an explanatory diagram showing the polarization generating optical system 130 of FIG. 2 in an enlarged manner. The polarization beam splitter 150 is configured by combining three substantially columnar light-transmitting members 151 to 153 having a bottom surface of a substantially right-angled isosceles triangle. In addition, as the translucent member, for example, glass is used.
[0064]
The first translucent member 151 is joined to the second and third translucent members 152 and 153 along the y direction. A polarized light separating film 150a is formed on the interface between the first and second light transmitting members 151 and 152, and the reflecting film 150b is formed on the third light transmitting member 153 substantially in parallel with the polarized light separating film 150a. Is formed.
[0065]
Here, the polarization separation film 150a is a thin film that separates incident non-polarized light (s + p) into p-polarized light and s-polarized light, and is formed of a dielectric multilayer film. The separated p-polarized light and s-polarized light have a light amount of approximately 50% of the incident light amount.
[0066]
The incident surface 151a of the first translucent member 151 corresponds to the incident surface 132 of the polarization generation optical system 130. The unpolarized light beam (s + p) incident from the incident surface 151a is separated into a p-polarized light beam and an s-polarized light beam by the polarization separation film 150a. The p-polarized light beam transmitted through the polarization separation film 150a passes through the second light-transmitting member 152 and is emitted from the emission surface 152a. On the other hand, the s-polarized light beam reflected by the polarization separation film 150a enters the third translucent member 153, is reflected by the reflection film 150b, and exits from the exit surface 153a. That is, the non-polarized light beam (s + p) incident on the first light-transmitting member 151 is separated into a p-polarized light beam and an s-polarized light beam along the y-direction, and the second light-transmitting member respectively. The light is emitted in the z direction from the emission surface 152a of the member 152 and the emission surface 153a of the third translucent member 153. The exit surface 152a of the second translucent member 152 and the exit surface 153a of the third translucent member 153 correspond to the exit surface 134 of the polarization generation optical system 130.
[0067]
The λ / 2 phase difference plate 160 has a function as a polarization conversion element that converts incident linearly polarized light into linearly polarized light whose polarization direction is orthogonal. In the present embodiment, as shown in FIG. 3, the λ / 2 retardation plate 160 is provided on the emission surface 152 a of the second translucent member 152. The p-polarized light beam emitted from the second translucent member 152 is converted into an s-polarized light beam by the λ / 2 retardation plate 160 and emitted. The s-polarized light beam is emitted from the third translucent member 153. As described above, the non-polarized light beam (s + p) incident on the polarization generating optical system 130 is converted into an s-polarized light beam and emitted.
[0068]
If a λ / 2 retardation plate is arranged on the exit surface of the third translucent member 153 from which the s-polarized light beam is emitted, the non-polarized light beam incident on the polarization generating optical system 130 can be converted into a p-polarized light beam. It can be converted into a bundle and ejected.
[0069]
Here, the incidence surface 151a of the first translucent member 151 has a substantially rectangular shape in which the ratio of the size x1 in the x direction to the size y1 in the y direction is approximately 2: 1. Further, the sizes x2 and y2 of the exit surface 152a of the second translucent member 152 from which the p-polarized light beam is emitted in the x direction and the y direction are the sizes x1 and x1 of the incident surface 151a in the x direction and the y direction, respectively. , Y1. Further, the sizes x3 and y3 of the exit surface 153a of the third translucent member 153 from which the s-polarized light beam is emitted in the x direction and the y direction are also the sizes x1 and x1 of the incident surface 151a in the x direction and the y direction, respectively. , Y1. Therefore, the emission surface 134 of the polarization generating optical system 130 corresponding to the emission surface 152a of the second light-transmissive member 152 and the emission surface 153a of the third light-transmissive member 153 is the same as that of the first light-transmissive member 151. It has twice the size in the y direction with respect to the incident surface 132 of the polarization generating optical system 130 corresponding to the incident surface 151a, and the ratio between the size in the x direction and the size in the y direction is approximately 1: 1. It is set to be.
[0070]
As can be understood from the above description, the polarization generating optical system 130 converts the unpolarized light beam incident from the incident surface 132 having a ratio of the size in the x direction to the size in the y direction of approximately 2: 1 into the size in the x direction. Is enlarged along the y-direction to almost twice as large as a light beam having a substantially square shape with a ratio of 1: 1 to the size in the y-direction, and is converted into an s-polarized light beam and emitted. Eject from surface 134.
[0071]
The light beam emitted from the polarization generation optical system 130 enters the first lens array 170 (FIG. 2).
[0072]
The first lens array 170 has a plurality of small lenses 172 arranged in a matrix. Each small lens 172 is a plano-convex lens, and the external shape when viewed from the z direction is set to be similar to the illumination area LA (liquid crystal light valve). The first lens array 170 divides the substantially parallel s-polarized light beam emitted from the polarization generating optical system 130 into a plurality of s-polarized partial light beams and emits the divided s-polarized light beams.
[0073]
The second lens array 180 has a plurality of small lenses 182 arranged in a matrix, and the same one as the first lens array 170 is used. The second lens array 180 and the superimposing lens 190 have a function of forming an image of each small lens 172 of the first lens array 170 on the illumination area LA.
[0074]
The superimposing lens 190 has a function of superimposing a plurality of s-polarized partial light beams having the same polarization direction on the illumination area LA as shown in FIG. At this time, the intensity distribution of the light illuminating the illumination area LA is substantially uniform.
[0075]
As can be seen from the above description, the first lens array 170 in the present embodiment corresponds to the lens array of the present invention, and the superimposing lens 190 corresponds to the superimposing optical system of the present invention. Note that the second lens array 180 can be omitted.
[0076]
C. Light source device:
FIG. 4 is an explanatory diagram showing the light source device 110 of FIG. 2 in an enlarged manner. FIG. 4A is a schematic plan view, and FIG. 4B is a schematic side view. FIG. 4C is a schematic front view as seen from the light emission direction.
[0077]
As the lamp 112, a metal halide lamp, a high-pressure mercury lamp, or the like can be used. As the reflector 114, a concave mirror having a spheroidal reflective concave surface is used. The light emitting portion 112c of the lamp 112 is arranged such that its center Pc is located at the first focal position of the spheroid, and the light reflected by the reflector 114 is condensed light converged at the second focal position of the spheroid. It becomes.
[0078]
Here, a reflection surface 112m is formed on the tube surface of the light emitting unit 112c as shown in the figure. More specifically, a plane parallel to the xy plane and including the center Pc of the light emitting unit 112c (a plane perpendicular to the light source optical axis 110ax that is the central axis of the light beam emitted from the light source device 110) is located on the + z direction side ( A reflection surface 112m is formed on a part of the substantially half tube surface located on the side of the light emitted from the light source device 110 in the traveling direction). More specifically, as shown in FIG. 4C, of the divided areas obtained by dividing the substantially half tube surface of the light emitting unit 112c into four areas, two sections facing each other in the y direction A reflection surface 112m is formed in the region. It should be noted that no reflection surface is formed in the two divided regions facing each other along the x direction. This reflecting surface 112m is, for example, Ta _Two O _Five And SiO _Two And a multi-layered film. However, the present invention is not limited to this, and any shape can be used as long as the reflecting surface 112m can be formed on the tube surface of the light emitting unit 112c.
[0079]
The reflecting surface 112m reflects light incident on the reflecting surface 112m as shown by a thick broken line in FIG. Then, the light reflected by the reflection surface 112m is emitted from an area on another tube surface of the light emitting unit 112c where the reflection surface is not formed. Then, if it is assumed that the light incident on the reflecting surface 112m is emitted without being reflected by the reflecting surface 112m, the light is closer to the light source optical axis 110ax than the position in the y direction where the light is reflected by the reflecting concave surface of the reflector 114. The light is reflected at a position near the center in the y direction.
[0080]
Thus, the cross-sectional shape La of the light beam emitted from the light source device 110 and incident on the collimating lens 120 is substantially circular when it is assumed that the reflection surface 112m is not formed. As shown in (2), the shape becomes smaller in the y direction than in the x direction. In the cross-sectional shape La of the light beam shown in FIG. 5, the light amount distribution is shown by contour lines.
[0081]
If it is assumed that the light incident on the reflecting surface 112m is emitted without being reflected by the reflecting surface 112m, the reflecting concave surface of the reflector 114 that reflects this light is unnecessary. Therefore, as shown in FIG. 4, unnecessary reflection concave surfaces of the reflector 114, specifically, reflection concave surfaces at both ends in the y direction are cut. Thus, the light source device 110 can be reduced in size, and the illumination optical system and the projector using the same can be reduced in size.
[0082]
By the way, even in the case of a lamp having no reflecting surface, instead of the lamp 112 as in the present example, if a reflector in which the reflecting concave surfaces at both ends in the y direction are cut off like the reflector 114 of the present example is used. It is possible to emit the same condensed light as the light source device 110 of this example. However, since the light that is supposed to be reflected on the reflecting concave surface of the cut reflector cannot be used as the condensed light, the amount of the condensed light is reduced by the amount of the unusable light. On the other hand, in the light source device 110 of the present example, the cross-sectional shape of the light beam emitted from the light source device 110 is reduced as compared with the x direction as shown in FIG. A shape having a small size in the direction can be obtained. Thereby, the cross-sectional shape of the light beam emitted from the light source device 110 is set such that the cross-sectional shape of the substantially parallel light beam emitted from the collimating lens 120 approaches the shape of the incident surface 132 of the polarization generating optical system 130. The light beam emitted from the light source device 110 can be efficiently incident on the incident surface 132 of the polarization generating optical system 130.
[0083]
As described above, in the illumination optical system 100 of the present example, by using the above-described light source device 110, the light use efficiency is improved as compared with the polarization generation optical system 930 used in the illumination optical system 900 of the conventional example. Omission and simplification of the polarization generation optical system can be achieved without lowering. Further, by using the illumination optical system 100 of the present example, the size and price of the projector can be reduced.
[0084]
D. Modification:
The present invention is not limited to the above-described examples and embodiments, but can be implemented in various modes without departing from the gist of the invention, and for example, the following modifications are possible.
[0085]
(1) In the illumination optical system 100 of the above embodiment, the cross-sectional shape of the light beam emitted from the light source device 110 is smaller in the y direction than in the x direction, and the light beam is substantially incident on the polarization generating optical system 130. Although the case where the parallel light beam is enlarged along the y-direction while being substantially parallel is shown, the cross-sectional shape of the light beam emitted from the light source device is smaller in the x-direction than in the y-direction. Alternatively, substantially parallel light beams incident on the polarization generating optical system may be enlarged along the x direction while being substantially parallel.
[0086]
(2) In the above embodiment, the case where the present invention is applied to a transmissive projector is described as an example. However, the present invention can also be applied to a reflective projector. Here, “transmissive” means that the electro-optical device as light modulating means transmits light, such as a transmissive liquid crystal panel, and “reflective” means reflective liquid crystal. This means that an electro-optical device as a light modulating means, such as a panel, is of a type that reflects light. When the present invention is applied to a reflection type projector, almost the same effects as those of a transmission type projector can be obtained.
[0087]
(3) In the above embodiment, the projector 1000 is provided with a liquid crystal light valve using a liquid crystal panel as a light modulation device, but may be provided with a micromirror light modulation device instead. As the micromirror type light modulation device, for example, a DMD (digital micromirror device) (trademark of TI) can be used. In general, any light modulation device may be used as long as it modulates incident light according to image information.
[0088]
(4) In the above embodiment, the projector 1000 displaying a color image is described as an example, but the same applies to a projector displaying a monochrome image.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an example of a projector to which the present invention has been applied.
FIG. 2 is an explanatory diagram showing the illumination optical system 100 of FIG. 1 in an enlarged manner.
FIG. 3 is an explanatory diagram showing an enlarged view of the polarization generation optical system 130 of FIG. 2;
FIG. 4 is an explanatory diagram showing the light source device 110 of FIG. 2 in an enlarged manner.
FIG. 5 is an explanatory diagram illustrating a cross-sectional shape of a light beam emitted from the light source device 110 and incident on the collimating lens 120.
FIG. 6 is an explanatory diagram showing a conventional illumination optical system 900.
FIG. 7 is an enlarged perspective view showing the polarization generating optical system 930 of FIG. 6 in an enlarged manner.
[Explanation of symbols]
1000 ... Projector
100 ... Illumination optical system
110 ... Light source device
110ax ... light source optical axis
112 ... Lamp (arc tube)
112c: Light emitting unit
112m ... Reflective surface
114 ... Reflector
120: Parallelizing lens
130 ... Polarization generating optical system
132 ... entrance surface
134 ... Emission surface
150 ... polarizing beam splitter
150a: polarized light separating film
150b: Reflective film
151: first light-transmitting member
151a: entrance surface
152: second translucent member
152a ... Emission surface
153: Third translucent member
153a ... Emission surface
160 ... λ / 2 phase difference plate
170: first lens array
172 ... Small lens
180: second lens array
182… Small lens
190 ... superimposed lens (superimposed optical system)
200: color light separation optical system (wavelength separation optical system)
220, 240 ... dichroic mirror
210, 230 ... Reflection mirror
250 ... Relay optical system
252 ... incident side lens
256 ... Relay lens
254,258 ... Reflection mirror
260 ... field lens (exit lens)
270 ... field lens
280 ... field lens
290 ... Optical filter
300B, 300G, 300R ... Liquid crystal light valve (light modulator)
400 ... Cross dichroic prism
410R: dielectric multilayer film
410B ... Dielectric multilayer film
500 Projection lens (projection optical system)
LA: Lighting area
La: sectional shape
Lax: System optical axis
Pc ... Center
900 ... Illumination optical system
920: Light source device
922 ... lamp
924 ... Reflector
926: Parallelizing lens
930: polarization generation optical system
940... First light beam expanding unit
940a: semi-transparent mirror film
940b: Reflective film
941-943: translucent member
950... Second light beam expanding section
950a: polarized light separating film
950b ... reflective film
951 to 956: translucent member
960 ... λ / 2 phase difference plate
970... First lens array
980: second lens array
972, 982 ... small lens
990: Superimposed lens

Claims (9)

An illumination optical system,
A light source device for emitting condensed light,
A lens for collimating the condensed light,
When two directions perpendicular to the center axis of the light beam emitted from the light source device and orthogonal to each other are defined as first and second directions, the size in the second direction is equal to the size in the first direction. It has a substantially rectangular light incident surface that is shorter than the light incident surface, and separates substantially parallel light beams emitted from the lens and incident on the light incident surface into two types of polarized light beams whose polarization directions are orthogonal to each other. By arranging the separated two types of polarized light beams along the second direction, the cross-sectional shape of the emitted light beam is expanded while being substantially parallel along the second direction, and separated. A polarization generating unit that generates substantially one type of polarized light beam having a predetermined polarization direction by aligning one polarization direction of the two types of polarized light beams with the other.
A lens array for dividing the substantially parallel polarized light beam emitted from the polarization generating unit into a plurality of partially polarized light beams,
A superimposing optical system for superimposing the plurality of partially polarized light beams on a predetermined illumination area,
The light source device,
An arc tube,
A reflector having a spheroidal reflective concave surface, and reflecting light emitted from a light emitting unit of the arc tube arranged at a focal position of the reflective concave surface,
A reflection surface is formed on a part of the light emitting unit on a tube surface of the light emitting tube such that a cross-sectional shape of a light beam emitted from the light source device has a shape close to the light incident surface. An illumination optical system characterized by the above. The illumination optical system according to claim 1, wherein
The reflecting surface is on a half tube surface located on the traveling direction side of the light beam, than a surface perpendicular to the central axis of the light beam emitted from the light source device and including the center of the light emitting unit, Of the divided regions obtained by dividing the half tube surface into four regions, two are not formed in the two divided regions facing each other along the first direction, and are not formed in the second region. An illumination optical system formed in the two divided areas. The illumination optical system according to claim 2, wherein
The reflector is configured such that, assuming that light is emitted from the two divided areas where the reflection surface is formed, the area of the reflective concave surface required to reflect light that can be emitted from the two divided areas is Illumination optics have been removed. An illumination optical system according to any one of claims 1 to 3, wherein
The polarization generator may have a ratio of the size of the light incident surface in the first direction to the size of the second direction of approximately 2: 1, and the first shape of the cross-sectional shape of the emitted light beam. A substantially parallel light beam incident from the light incident surface is doubled along the second direction so that the ratio of the size in the direction to the size in the second direction is approximately 1: 1. , Illumination optics An illumination optical system according to any one of claims 1 to 4, wherein
The polarization generator,
Having the light incident surface, separating the substantially parallel light beams incident from the light incident surface into two types of polarized light beams orthogonal to each other along the second direction and emitting the light beams while being substantially parallel; A polarizing beam splitter that emits a polarized light beam whose cross-sectional shape is enlarged along the second direction;
A phase difference plate for aligning one polarization direction of the two types of polarized light beams emitted from the polarization beam splitter with the other polarization direction,
An illumination optical system comprising: A projector,
An illumination optical system according to any one of claims 1 to 5,
A light modulation device that modulates light from the illumination optical system according to image information,
A projection optical system that projects modulated light obtained by the light modulation device,
A projector comprising: A light source device,
An arc tube,
A reflector having a spheroidal reflective concave surface, and reflecting light emitted from a light emitting unit of the arc tube arranged at a focal position of the reflective concave surface,
The arc tube has a cross section of a light beam emitted from the light source device when two directions perpendicular to a central axis of the light beam emitted from the light source device and orthogonal to each other are defined as first and second directions. A light source device, wherein a reflection surface is formed on a part of the tube surface of the light emitting unit so that the shape is smaller in the second direction than in the first direction. The light source device according to claim 7,
The reflecting surface is on a half tube surface located on the traveling direction side of the light beam, than a surface perpendicular to the central axis of the light beam emitted from the light source device and including the center of the light emitting unit, Of the divided regions obtained by dividing the half tube surface into four regions, two are not formed in the two divided regions facing each other along the first direction, and are not formed in the second region. Are formed in two divided areas,
The reflector is configured such that, assuming that light is emitted from the two divided areas where the reflection surface is formed, the area of the reflective concave surface required to reflect light that can be emitted from the two divided areas is Light source device has been removed. An arc tube,
One half of the light-emitting unit, which is divided by a plane including the center of the light-emitting unit that emits light perpendicular to a predetermined central axis, on one half of the light-emitting unit, An arc tube, wherein a reflection surface is not formed in two opposing divisional regions of the divided regions, and a reflection surface is formed in the other two opposing divisional regions.

Images