JP2009175394A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector capable of achieving higher resolution and higher luminance of a projection image, and reduction of irregular color of the projection image. <P>SOLUTION: The projector 1 includes: a first optical system 4 and a second optical system 5 which include color separation optical devices 41 and 51 separating luminous flux emitted from a light source 211 to a plurality of color light beams, and a plurality of optical modulation devices 42R, 42G and 42B, and 52R, 52G and 52B modulating the plurality of separated color light beams in accordance with image information for every color light beam so as to form an optical image, and where optical paths are respectively set for the respective separated color light beams; a composite optical system 6 compositing the optical images formed by the first optical system 4 and the second optical system 5 respectively; and a projection optical system 7 projecting the composited optical image. The optical path of any color light beam R set in the first optical system 4 is different from the optical path set in the second optical system 5 for the same color light beam R as the color light beam R. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a projector that modulates a light beam emitted from a light source according to image information to form an optical image and project it.

2. Description of the Related Art Conventionally, there is known a projector that projects an optical image by modulating a light beam emitted from a light source according to input image information.
As this projector, a three-plate projector that forms an optical image using three light modulation devices is known. The three-plate projector uses a light source and a light beam emitted from the light source as red, green, and blue. A color separation optical device that separates the three color lights, three light modulation devices that form an optical image by modulating the separated color light for each color light according to image information, and an optical that is formed by each light modulation device A color synthesizing optical device that synthesizes the images; and a projection optical device that projects an optical image synthesized by the color synthesizing optical device onto a projection surface.
Incidentally, in recent years, a projector that forms an optical image using six light modulation devices has been proposed with the aim of increasing the resolution and brightness of a projected image (see, for example, Patent Document 1).

This 6-plate projector accommodates two sets of optical systems including the color separation optical device, the light modulation device, and the color synthesis optical device described above in one housing, and the light beam emitted from the light source is received by the polarization beam splitter array. Separated into two types of linearly polarized light beams, each optical system forms an optical image with each linearly polarized light beam, and finally, the optical image formed by each optical system is synthesized by a polarizing beam splitter. It is projected onto the projection surface from the system.
In such a 6-plate projector, it is possible to realize a high resolution of the projected image by synthesizing the projected image by shifting the pixel position of the light modulation device of each optical system by 1/2 pixel. Since an optical image is formed for each of the two types of linearly polarized light beams separated by the polarizing beam splitter, the amount of light absorbed by a light modulation device such as a liquid crystal panel can be reduced by combining the optical images. It is possible to achieve high luminance by reducing the light utilization rate.
Further, by supplying light beams from different light sources to the respective optical systems, it is possible to further increase the brightness of the projected image.

Japanese Patent Laid-Open No. 1-126678

  However, the technique described in Patent Document 1 is merely a technique in which the same optical system is housed in one housing. For this reason, when there are optical path differences in the optical paths of the three color lights separated by the color separation optical device and color unevenness or the like occurs in the projected image projected from one optical system, these are overlapped by the two optical systems. In a 6-plate projector that forms a projection image together, there is a problem that the color unevenness of the projection image is more emphasized.

  An object of the present invention is to provide a projector capable of increasing the resolution and brightness of a projected image and reducing color unevenness of the projected image.

The projector according to the present invention is
A projector that modulates a light beam emitted from a light source according to image information to form an optical image and projects the optical image;
A color separation optical device that separates a light beam emitted from the light source into a plurality of color lights, and a plurality of color lights separated by the color separation optical device are modulated for each color light according to image information to form an optical image A first optical system and a second optical system each having an optical path set for each color light separated by the color separation optical device,
A combining optical system that combines optical images formed by the first optical system and the second optical system,
A projection optical system for projecting an optical image synthesized by the synthesis optical system,
The optical path of any color light set in the first optical system is different from the optical path set in the second optical system for the same color light as this color light.

Here, for example, if the first optical system and the second optical system perform color separation on red, green, and blue three-color light, the optical path of red light set in the first optical system and the second optical system Since the optical path of red light set in the system is different, it is necessary to replace the optical path of the other color light, so that the optical path of either blue or green color light is also the first optical system and the second optical system. It will be different in the system.
According to the present invention, since the optical path of certain colored light set in the first optical system is different from the optical path of the same colored light set in the second optical system, the color light of the first optical system Even if color irregularity occurs in a projection image formed with a long optical path and a large attenuation of light, the colored light is reduced in the optical path different in the second optical system to form a projection image. By combining the projection images formed by the optical system and the second optical system, color unevenness of the projection image can be suppressed.

In the present invention, a polarization separation optical device that separates the light beam emitted from the light source into two types of linearly polarized light beams is provided at the subsequent stage of the light source,
In the first optical system, an optical image is formed for any one of the linearly polarized light beams,
In the second optical system, it is preferable to form an optical image for the other linearly polarized light beam.
According to the present invention, the light beam emitted from the light source is separated into two types of linearly polarized light beams by the polarization separation optical device, and each linearly polarized light beam is modulated by separate optical systems to form an optical image. When modulating a light beam with a uniform polarization direction, the light amount of the light beam absorbed by the polarizing plate or the like can be reduced, and the attenuation of light can be reduced to increase the brightness of the projected image.

In the present invention,
Each optical path for each color light of the first optical system and the second optical system is set by arranging a plurality of optical elements that transmit or reflect each color light,
Among the optical paths for the respective color lights of the first optical system and the second optical system, dummy optical elements are arranged in the optical path of the color light set by arranging fewer optical elements than the optical paths of the other color lights. It is preferable that the attenuation amount of the color light is adjusted.
Here, as the dummy optical element, for example, an element that reflects a part of the incident light beam, transmits a part thereof, and attenuates the amount of the incident light beam can be employed. Can be used.
According to the present invention, since the color light of the optical path with few optical elements is attenuated by the dummy optical element, the color light attenuated to the same extent as the color light of other optical paths with many optical elements can be obtained. It is possible to improve the quality of the projected image by making the color unevenness corresponding to the color light within the same degree.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 shows a projector 1 according to an embodiment of the present invention. The projector 1 includes an illumination optical device 2, a polarization separation optical device 3, a first optical system 4, and a second optical system 5. Although not shown, these optical elements are housed in a single casing. The projector 1 modulates the light beam emitted from the illumination optical device 2 according to image information input by each of the first optical system 4 and the second optical system 5 to form an optical image, and combines the combined optical system 6. The optical images formed by the optical systems 4 and 5 are synthesized and the optical image synthesized by the projection optical system 7 is projected.

The illumination optical device 2 includes a light source device 21, a first lens array 22, a second lens array 23, and a superimposing lens 24.
The light source device 21 includes a light source lamp 211 as a light source that emits a radial light beam, and a reflector 212 that reflects the emitted light emitted from the light source lamp 211 and converges it to a predetermined position. As such a light source lamp 211, a halogen lamp, a metal halide lamp, a high-pressure mercury lamp, or the like can be used. In addition, as the reflector 212, a parabolic reflector having a rotating paraboloid as a reflecting surface or an ellipsoidal reflector reflecting a rotating ellipsoid can be employed.

Each of the first lens array 22 and the second lens array 23 has a configuration in which corresponding small lenses are arranged in a matrix, and the first lens array 22 converts the light beam incident from the light source device 21 into a plurality of partial light beams. The image is divided and imaged in the vicinity of the second lens array 23.
The second lens array 23, together with the superimposing lens 24 located in the latter stage of the optical path, displays images emitted from the small lenses of the first lens array 22 as liquid crystal panels 42R, 42G, and 42B constituting the first optical system 4 described later. A plurality of partial light beams divided by the first lens array 22 are superimposed on the image forming regions of the liquid crystal panels 52R, 52G, and 52B constituting the second optical system 5.

  The polarization separation optical device 3 is a plate-like body disposed at an inclination of about 45 degrees with respect to the optical path center axis of the light beam emitted from the illumination optical device 2, and is a dielectric on a transparent substrate such as BK7 or quartz glass. An optical element in which a multilayer film is formed. The dielectric multilayer film of the polarization separation optical device 3 has a function of separating a randomly polarized light beam emitted from the illumination optical device 2 into two kinds of linearly polarized light beams, and linearly polarized light parallel to the incident surface of the light beam. Transmits a light beam (P-polarized light beam) and reflects linearly polarized light (S-polarized light beam) perpendicular to the incident surface. The S-polarized light beam separated by the polarization separation optical device 3 is supplied to the first optical system 4 disposed in the direction facing the projection optical system 7, and the P-polarized light beam is perpendicular to the projection optical system 7. To the second optical system 5 arranged in

The first optical system 4 is a part that modulates the S-polarized light beam separated by the polarization separation optical device 3 according to image information to form an optical image, and includes a color separation optical device 41, a light modulation device 42, and A color combining optical device 43 is provided.
The color separation optical device 41 has a function of separating an incident S-polarized light beam into three color lights of red light (R), green light (G), and blue light (B), and includes dichroic mirrors 411 and 412 and a reflection mirror. 413, 414, 415 are provided.

The dichroic mirrors 411 and 412 are optical elements that are arranged with an inclination of approximately 45 degrees with respect to the optical path center axis of the S-polarized light beam, and have a dielectric multilayer film formed on a transparent substrate such as BK7 or quartz glass. The dielectric multilayer films of the dichroic mirrors 411 and 412 have a function of reflecting a light beam in a specific wavelength region, transmitting other light beams, and separating the S-polarized light beam into a plurality of color lights. The dichroic mirror 411 disposed at the front stage of the optical path reflects the blue light (B) and transmits the other red light (R) and green light (G), while the dichroic mirror 412 disposed at the rear stage of the optical path. , Green light (G) is reflected and red light (R) is transmitted.
The reflection mirrors 413, 414, and 415 are optical elements that guide the color lights R, G, and B separated by the dichroic mirrors 411 and 412 to the liquid crystal panels 42R, 42G, and 42B constituting the light modulation device 42, respectively. Consists of mirrors.

The light modulation device 42 includes three liquid crystal panels 42R, 42G, and 42B, three incident-side polarizing plates 421R, 421G, and 421B disposed in front of the optical paths of the liquid crystal panels 42R, 42G and 42B, and the liquid crystal panels 42R, 42G and 42B, and three exit side polarizing plates 422R, 422G, and 422B disposed in the latter stage of the optical path.
The three incident-side polarizing plates 421R, 421G, and 421B are configured by forming a polarizing film on a transparent substrate such as BK7 or quartz glass, and have the property of transmitting the S-polarized light beam separated by the polarization separation optical device 3. Then, the light flux whose phase is polarized is absorbed by the dichroic mirrors 411 and 412 in the middle of the optical path.
The liquid crystal panels 42R, 42G, and 42B have a configuration in which a liquid crystal as an electro-optical material is hermetically sealed in a pair of transparent glass substrates, and the alignment state of the liquid crystal is controlled according to input image information. The polarization direction of polarized light emitted from the incident-side polarizing plates 421R, 421G, and 421B is modulated.
The three exit-side polarizing plates 422R, 422G, and 422B transmit only the P-polarized light beam among the light beams emitted through the liquid crystal panels 42R, 42G, and 42B, and absorb the other light beams.

  The color synthesizing optical device 43 has a function of synthesizing the modulated light beams emitted from the respective exit side polarizing plates 422R, 422G, and 422B to form a color image, and has a substantially square shape in plan view in which four right-angle prisms are bonded. And a cross dichroic prism in which two dielectric multilayer films are formed at the interface where the right-angle prisms are bonded together. One of the two dielectric multilayer films reflects red light (R) and transmits green light (G), and the other reflects blue light (B) and transmits green light (G). These dielectric multilayer films combine red light (R), green light (G), and blue light (B) to form a color image.

The second optical system 5 is a part that modulates the P-polarized light beam separated by the polarization separation optical device 3 according to image information to form an optical image, and is basically the same as the first optical system 4. The color separation optical device 51, the light modulation device 52, and the color synthesis optical device 53 are provided, and their functions and operations are basically the same.
The color separation optical device 51 includes dichroic mirrors 511 and 512, and reflection mirrors 513, 514, and 515. The dichroic mirror 511 disposed in the front stage of the optical path of the P-polarized light beam reflects red light (R). A dielectric multilayer film that transmits green light (G) and blue light (B) is formed on a transparent substrate, and a dichroic mirror 512 disposed in the subsequent stage reflects green light (G) to generate blue light. A dielectric multilayer film that transmits (B) is formed on the transparent substrate.

  Similar to the first optical system 4, the light modulation device 52 includes three liquid crystal panels 52R, 52G, and 52B, and incident-side polarizing plates 521R, 521G, and 521B disposed in front of the optical paths of the liquid crystal panels 52R, 52G, and 52B. And emission-side polarizing plates 522R, 522G, and 522B disposed in the rear stage of the optical path of the liquid crystal panels 52R, 52G, and 52B. However, unlike the first optical system 4, since the light beam supplied to the second optical system 5 is a P-polarized light beam, the three incident-side polarizing plates 521R, 521G, and 521B have the property of transmitting the P-polarized light beam. The three exit-side polarizing plates 522R, 522G, and 522B are different in that they have a property of transmitting an S-polarized light beam.

In the first optical system 4 and the second optical system 5 as described above, dummy optical elements 44 and 54 are disposed downstream of the light path of the reflected light of the dichroic mirrors 412 and 512 and upstream of the incident-side polarizing plates 421G and 521G. The dummy optical elements 44 and 54 are made of optical glass such as BK7.
The dummy optical element 44 of the first optical system 4 and the dummy optical element 54 of the second optical system 5 are in the optical path of red light (R), green light (G), and blue light (B) in each optical system 4 and 5. Is provided to adjust the number of optical elements arranged at the same position so that the attenuation of the amount of light of each color light is the same.

Specifically, the dichroic mirrors 411 and 412 and the reflection mirrors 414 and 415 are arranged in the first optical system 4 in the optical path of the red light (R) of the first optical system 4 and the second optical system 5. The dichroic mirror 511 and the reflection mirror 513 are arranged in the two optical systems 5, and the red light (R) is transmitted or reflected through a total of six optical elements.
In the optical path of blue light (B), a dichroic mirror 411 and a reflection mirror 413 are arranged in the first optical system 4, and dichroic mirrors 511 and 512 and reflection mirrors 514 and 515 are arranged in the second optical system 5. In addition, blue light (B) is transmitted or reflected through a total of six optical elements.

On the other hand, when the dummy optical elements 44 and 54 are not provided, the dichroic mirrors 411 and 412 are arranged in the first optical system 4 and the dichroic mirrors 511 and 512 are arranged in the second optical system 5 in the green light (G) optical path. Arranged, green light (G) transmits or reflects only a total of four optical elements.
In the state where the dummy optical elements 44 and 54 are not disposed, the attenuation of the green light (G) in the optical path is small. Therefore, the projection image projected from the projection optical system 7 has the amount of green light (G). There is a high possibility that many projected images will be obtained.
Therefore, in the present embodiment, dummy optical elements 44 and 54 are arranged in the optical path of green light (G) so that the number of optical elements through which green light (G) is transmitted or reflected is the same as other color lights. did.
According to such dummy optical elements 44 and 54, the number of optical elements that transmit or reflect red light (R), green light (G), and blue light (B) can be made the same. The attenuation of the amount of light when transmitting or reflecting the light can be made the same, the color unevenness corresponding to the color light of the projection image projected from the projection optical system 7 can be made the same level, and the quality of the projection image can be improved. it can.

The combining optical system 6 combines the optical images formed by the first optical system 4 and the second optical system 5 and has a substantially square shape in plan view in which two triangular prisms are bonded together. A dielectric multilayer film is formed at the interface where the two are bonded together. This dielectric multilayer film is a polarization separation film that transmits a P-polarized light beam and reflects an S-polarized light beam, as in the polarization separation optical device 3 described above.
As shown in FIG. 2, the combining optical system 6 is configured so that the pixel P2 of the second optical system 5 is ½ pixel in the horizontal direction and ½ in the vertical direction with respect to the pixel P1 of the first optical system 4. The optical images of the optical systems 4 and 5 are synthesized by shifting the pixels.
Although not shown in FIG. 1, the projection optical system 7 is composed of a combination lens in which a plurality of lenses are arranged in the lens barrel with the optical axis aligned, and an optical image synthesized by the synthesis optical system 6 is projected onto the projection surface. Project to the top.

  In the projector 1 according to this embodiment, in the first optical system 4, the optical path of blue light (B) is set to be the shortest, the optical path of red light (R) is set to be the longest, and in the second optical system 5, The optical path of blue light (B) is set to be the longest, and the optical path of red light (R) is set to be the shortest. Therefore, when the optical image formed by the first optical system 4 and the optical image formed by the second optical system 5 are combined in the combining optical system 6, color unevenness due to the optical path difference between the optical systems 4 and 5 is eliminated. Since they can complement each other, it is possible to suppress color unevenness in the synthesized projection image.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the following description, parts that have already been described are assigned the same reference numerals and description thereof is omitted.
In the projector 1 according to the first embodiment described above, the polarization separation optical device 3 is provided at the subsequent stage of the illumination optical device 2, and the light beam emitted from the illumination optical device 2 is separated into a P-polarized light beam and an S-polarized light beam. The optical system 4 forms an optical image based on the S-polarized light beam, the second optical system 5 forms an optical image based on the P-polarized light beam, and the combined optical system 6 combines the optical images to form a projection image. Was.
In contrast, in the projector 8 according to the second embodiment, as shown in FIG. 3, the illumination optical device 2 is provided in each of the first optical system 4 and the second optical system 5. Based on the emitted light beam, an optical image is formed by each of the first optical system 4 and the second optical system 5, and each optical image is combined by the combining optical system 6 to form a projection image. Is different.

Also, polarization conversion elements 81 and 82 are provided between the second lens array 23 and the superimposing lens 24 of each illumination optical device 2. The polarization conversion elements 81 and 82 are provided to convert the light beam emitted from the illumination optical device 2 into substantially one type of linearly polarized light beam. The polarization conversion element 81 of the first optical system 4 is an illumination optical device. The light beam emitted from the device 2 is converted into an S-polarized light beam. On the other hand, the polarization conversion element 82 of the second optical system 5 converts the light beam emitted from the illumination optical device 2 into a P-polarized light beam.
The polarization conversion elements 81 and 82 are plate-like bodies formed by joining a plurality of prisms having a parallelogrammatic cross section in which one diagonal is 45 deg and the other diagonal is approximately 135 deg. Polarization separation films and total reflection mirrors are alternately deposited on the interface to be joined.
A plurality of half-wave retardation plates are provided at a predetermined pitch on the light exit surfaces of the polarization conversion elements 81 and 82.

In such polarization conversion elements 81 and 82, when a light beam is incident on the surface on which the polarization separation film is formed, the P-polarized light beam is transmitted and emitted as it is, and the S-polarized light beam is bent at a substantially right angle by the polarization separation film. Then, it is again bent at a right angle by the total reflection mirror and emitted.
Either the emitted P-polarized light beam or S-polarized light beam is converted into a 90 deg polarization direction by a half-wave retardation plate provided at a later stage, thereby converting the incident light beam into one kind of linearly polarized light beam. It becomes possible. The polarization conversion element 81 is provided at a position where the half-wave retardation plate corresponds to the polarization separation film, and the polarization conversion element 82 is provided at a position where the half-wave retardation plate corresponds to the total reflection mirror. It has been.

In the projector 8 according to the second embodiment, in addition to the effects of the projector 1 according to the first embodiment described above, the illumination optical device 2 that supplies the light beams to the optical systems 4 and 5 is provided independently. Therefore, a large amount of light of the optical image formed by each of the optical systems 4 and 5 can be secured, and the brightness of the projected image can be increased.
In addition, since the illumination optical device 2 is independently driven and controlled, the amount of light emitted from each illumination optical device 2 can be adjusted. Therefore, the brightness of the projection image synthesized by the synthesis optical system 6 can be adjusted. Unevenness, color unevenness, etc. can be further reduced.

[Modification of Embodiment]
In addition, this invention is not limited to embodiment mentioned above, The deformation | transformation as shown below is also included.
In the above-described embodiment, the transmissive liquid crystal panels 42R, 42G, 42B, 52R, 52G, and 52B are employed as the light modulation device. However, the present invention is not limited to this, and for example, a reflective liquid crystal panel or a micromirror The present invention may be employed in a projector that composes two optical systems with a device using the, and synthesizes these to project a projected image.
In addition, the specific structure, shape, and the like when implementing the present invention may be other structures as long as the object of the present invention can be achieved.

1 is a schematic diagram illustrating a structure of a projector according to a first embodiment of the invention. The schematic diagram showing the state of the projection image of the 1st, 2nd optical system synthesize | combined by the synthetic | combination optical system in the said embodiment. The schematic diagram showing the structure of the projector which concerns on 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Projector, 2 ... Illumination optical apparatus, 3 ... Polarization separation optical apparatus, 4 ... 1st optical system, 5 ... 2nd optical system, 6 ... Synthesis optical system, 7 ... Projection optical system, 8 ... Projector, 21 ... Light source Device: 22 ... 1st lens array, 23 ... 2nd lens array, 24 ... Superimposition lens, 41 ... Color separation optical device, 42 ... Light modulation device, 42R, 42G, 42B ... Liquid crystal panel, 43 ... Color synthesis optical device, 44 ... Dummy optical element, 51 ... Color separation optical device, 52 ... Light modulation device, 52R, 52G, 52B ... Liquid crystal panel, 53 ... Color synthesis optical device, 54 ... Dummy optical element, 81, 82 ... Polarization conversion element, 211 ... light source lamp, 212 ... reflector, 411, 412 ... dichroic mirror, 413, 414, 415 ... reflection mirror, 421R, 421G, 421B ... incident side polarizing plate, 422R, 422G, 22B: Emission side polarizing plate, 511, 512 ... Dichroic mirror, 513, 514, 515 ... Reflection mirror, 521R, 521G, 521B ... Incident side polarizing plate, 522R, 522G, 522B ... Emission side polarizing plate, P1 ... Pixel, P2 ... pixel

Claims (3)

A projector that modulates a light beam emitted from a light source according to image information to form an optical image and projects the optical image;
A color separation optical device that separates a light beam emitted from the light source into a plurality of color lights, and a plurality of color lights separated by the color separation optical device are modulated for each color light according to image information to form an optical image A first optical system and a second optical system each having an optical path set for each color light separated by the color separation optical device,
A combining optical system that combines optical images formed by the first optical system and the second optical system,
A projection optical system for projecting an optical image synthesized by the synthesis optical system,
A projector characterized in that an optical path of any one of the colored lights set in the first optical system is different from an optical path set in the second optical system for the same colored light as this colored light. The projector according to claim 1, wherein
A polarization separation optical device that separates the light beam emitted from the light source into two types of linearly polarized light beams is provided at the subsequent stage of the light source,
In the first optical system, an optical image is formed for any one of the linearly polarized light beams,
In the second optical system, an optical image is formed with respect to one of the other linearly polarized light beams. In the projector according to claim 1 or 2,
Each optical path for each color light of the first optical system and the second optical system is set by arranging a plurality of optical elements that transmit or reflect each color light,
Among the optical paths for the respective color lights of the first optical system and the second optical system, dummy optical elements are arranged in the optical path of the color light set by arranging fewer optical elements than the optical paths of the other color lights. And the attenuation amount of the color light is adjusted.

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