JP3269362B2 - LCD projector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector having an illumination optical system including a polarization conversion optical system and an optical integrator for obtaining a bright and uniform projected image.

[0002]

2. Description of the Related Art In the field of conventional liquid crystal projectors,
For example, as disclosed in JP-A-6-265887 or JP-A-7-120753, an illumination optical system including a polarization conversion optical system and an optical integrator for obtaining a bright and uniform projection image with an illuminance distribution is used. A liquid crystal projector having the same is known.

[0003]

However, in a liquid crystal projector having an illumination optical system including the above-mentioned polarization conversion optical system and optical integrator, the polarization conversion is completed on the light source side rather than the light beam entering the optical integrator. There is a problem that the size of the illumination optical system increases in a direction perpendicular to the main optical axis of the illumination optical system. Furthermore, space for the polarization conversion optical system and the space for the optical integrator are required, and there is a problem that the size of the illumination optical system increases in the main optical axis direction of the illumination optical system. Further, there is a problem that the polarization conversion optical system itself that effectively uses light from the light source itself is large, and furthermore, the configuration is complicated. SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal projector having an illumination optical system that has a compact and simple configuration and high light use efficiency even when a polarization conversion optical system and an optical integrator are used.

In order to achieve the above object, the present invention provides an optical
A source, illumination optics, and illuminated by the illumination optics
In a liquid crystal projector having a liquid crystal panel,
The illumination optical system includes a first lens array and a
Optical integrator consisting of a second lens array
And random polarized light emitted from the light source into a predetermined polarized light.
A polarization conversion optical system that converts the light into polarized light in the direction,
Near the second lens array of the optical integrator
A half-wave plate is placed beside, and the polarization conversion optical system is
The second lens on the liquid crystal panel side of the lens array.
It is arranged on the light source side of the array (claim 1).
Further, the second lens array is provided with the first lens array.
It is composed of twice as many lenses as
(Claim 2). In addition, the above-mentioned polarization conversion optical system is polarized light separation.
A surface and a total reflection surface are used (claim 3). Also,
The polarization conversion optical system uses a birefringent material.
(Claim 4). In addition, the illumination light from the light source is
In the illumination optical system of a liquid crystal projector that leads, or the light source
First lens array and second lens arranged in this order
An optical integrator consisting of an array and
The second lens array is closer to the liquid crystal panel than the first lens array.
It is located closer to the light source than the lens array and emits light from the light source.
Randomized polarized light into polarized light having a predetermined polarization direction
Conversion optical system and optical integrator
波長 wavelength located near the second lens array of the
And a plate (claim 5).

According to the first aspect of the present invention, a half of the optical integrator is placed near the second lens array.
A wavelength plate and a polarization conversion optical system are arranged closer to the light source than the second lens array, and the image forming action of the first lens array is used to save space in a direction perpendicular to the main optical axis of the illumination optical system. Since polarization separation can be performed, the illumination optical system can be downsized.
Further, by disposing the polarization conversion optical system between the first and second lens arrays, the polarization conversion optical system and the optical integrator occupy the same space, so that the illumination optical system is arranged in the main optical axis direction of the illumination optical system. It is downsized.

[0006] According to the second aspect of the invention, the second
The number of lenses included in the first lens array is twice as large as the number of lenses included in the first lens array, and only half of the lenses are provided with a half-wave plate, whereby the first lens array after the polarization conversion is performed. Can be correctly formed on the liquid crystal panel, so that a bright and uniform projected image with high efficiency can be obtained. In addition, 請
According to the third aspect of the present invention, the polarization conversion is performed by using the optical path difference between the polarization splitting surface and the total reflection surface, so that the polarization conversion optical system can be easily manufactured and also compact. According to the fourth aspect of the present invention, even if a birefringent material is used, the polarization conversion optical system can be reduced in size and can have a simple configuration.

[0007]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a first embodiment of the present invention. In FIG. 1, a light beam of white random polarized light emitted from a light source 101 is reflected by a reflector 102 and an unnecessary wavelength region is cut by an IR-UV cut filter 103, and then a first lens array constituting an optical integrator It is incident on 104.
The light beam from the light source is split into a plurality of light beams by the first lens array 104, enters the polarization beam splitter 105, and is split by the polarization splitting surface 105a into two light beams 124 and 125 of two linearly polarized light components orthogonal to each other. . Of these, the light flux 124 transmitted through the polarization splitting surface 105a
Is emitted from the polarizing beam splitter 105 and is guided to a second lens array 109 constituting an optical integrator.

On the other hand, the light beam 125 reflected by the polarization splitting surface 105a is totally reflected by the total reflection surface 105b, and then exits the polarization beam splitter 105 to be output to the second lens array 109.
It is led to. The polarization beam splitter 105 at a portion where the light beam 125 reflected by the polarization splitting surface 105a passes after being totally reflected by the total reflection surface 105b is applied to the polarization splitting surface 10a.
The glass member 1 is configured to correct the optical path difference between the light beam 124 passing through the light separating surface 5a and the light beam 125 reflected by the polarization splitting surface 105a.
05c is joined. The light beam 124 transmitted through the polarization separation surface 105a and the light beam 1 reflected by the polarization separation surface 105a
Numerals 25 form the same number of small light sources as the number of light beams divided by the first lens array 104 in the vicinity of the second lens array 109 due to the image forming action of the first lens array 104.

The second lens array 109 has a number of lenses equal to the number of small light sources formed by the light beam 124 and the light beam 125, that is, twice the number of lenses included in the first lens array 104. Corresponds to each small light source. Of the small light sources formed on the second lens array 109, the light flux 124 or the light flux 12
By providing the half-wavelength plate 109a to the lens corresponding to any one of the small light sources formed in step 5, the polarization directions of all the small light sources can be made uniform.

In FIG. 1, a half-wave plate 109a is provided on the side of the small light source formed by the light flux 125. In the present embodiment, the light fluxes emitted from all the small light sources formed near the second lens array 109 and having their polarization directions aligned are the light fluxes necessary for illuminating the liquid crystal panels 106 to 108. As described above, since the light fluxes reaching the liquid crystal panels 106 to 108 do not include the unnecessary light fluxes of the polarized light components, unnecessary heat generation due to the absorption of the unnecessary light fluxes of the polarized light components by the polarizing plate (not shown) in the liquid crystal panel is generated. This can prevent the deterioration of the polarizing plate and the like.

Further, it is possible to illuminate the liquid crystal panel with a larger amount of light flux of a polarization component necessary for illumination than when the light flux of an unnecessary polarization component reaches the liquid crystal panel, and obtain a brighter projected image. Can be Light source 101 and second
The individual lenses on the lens array 109 are optically conjugate with each other, and the image of the light source 101 is
An image is formed on the individual lenses on the image 09, each of which is a secondary light source. The light beam guided to the second lens array 109 is converted by the dichroic mirrors 110 and 111 into an R beam.
-It is separated into three wavelength bands of G and B. The luminous flux in the R wavelength band transmitted through the dichroic mirror 110 is reflected by the total reflection mirror 112 and transmitted through the field lens 113, and then illuminates the liquid crystal panel 106. After passing through 114, the liquid crystal panel 107 is illuminated, and the light flux in the B wavelength band transmitted through the dichroic mirror 111 is totally reflected by the mirrors 116 and 117 and the relay optical system 1
After passing through the field lens 115 by 18 and 119, the liquid crystal panel 108 is illuminated. The distance between the liquid crystal panel 108 and the second lens array 109 is
Since the distance between the second lens array 109 and the second lens array 109 is different, the illumination state of the liquid crystal panel 108 is changed using the relay optical systems 118 and 119.
And the same lighting condition.

The liquid crystal panels 106 to 108 are telecentricly illuminated by the field lenses 113 to 115. Here, the individual lenses on the first lens array 104 and the liquid crystal panels 106 to 108 are in an optically conjugate relationship, and each light beam split by the first lens array 104 is Since the liquid crystal panels 106 to 108 are superposed on each other, the liquid crystal panels 106 to 108 are illuminated with a uniform light amount distribution. Therefore, the R, G, and B images displayed on the liquid crystal panels 106 to 108 are combined by the dichroic prism 120 and projected onto a screen (not shown) as a color image with a uniform illuminance distribution by the projection lens 121. Is done.

As described above, in the present embodiment, 1/2
By arranging the wave plate near the second lens array forming the optical integrator and arranging the polarization conversion optical system between the first and second lens arrays, the light beam from the light source can be very efficiently It can be used well for illuminating liquid crystal panels and can share the space occupied by the polarization conversion optical system and the optical integrator, so that a bright and uniform illuminance distribution projected image can be obtained, and the illumination optical system is small in the main optical axis direction. It realizes a compact and compact LCD projector. In the present embodiment, the light source 10
Although a metal halide lamp was used for 1, it goes without saying that a xenon lamp or a halogen lamp may be used.

FIG. 2 and FIG. 3 are main part configuration diagrams of the illumination optical system according to the second and third embodiments of the present invention.

In FIG. 2, a randomly polarized light beam emitted from a light source 201 is reflected by a reflector 202 and cut off an unnecessary wavelength range by an IR-UV cut filter 203, and then forms a first optical integrator. The light enters the lens array 204. The light beam from the light source is split into a plurality of light beams by the first lens array 204, then enters the polarization beam splitter 205, and is separated into two linearly polarized light beams 224 and 225 orthogonal to each other by the polarization splitting surface 205a. Is done. Of these, the light flux 224 reflected by the polarization separation surface 205a
Is emitted from the polarizing beam splitter 205 and is guided to a second lens array 209 constituting an optical integrator.

On the other hand, the light beam 2 transmitted through the polarization separation surface 205a
Reference numeral 25 denotes the polarization separation surface 2 after transmitting through the polarization separation surface 205a.
After traveling straight through the optical path 226 generated by the interval 205c between the light-reflection surface 05a and the total reflection surface 205b and being totally reflected by the total reflection surface 205b, the light is emitted from the polarization beam splitter 205 and guided to the second lens array 209. The light beam 224 transmitted through the polarization separation surface 205a and the light beam 2 reflected by the polarization separation surface 205a
Numerals 25 form the same number of small light sources as the number of light beams divided by the first lens array 204 in the vicinity of the second lens array 209 by the image forming action of the first lens array 204. At this time, the light flux 22 reflected by the total reflection surface 205b
The small light source formed by the light source 5 is different from the small light source formed by the light beam 224 reflected by the polarization separation surface 205a by the distance of the optical path 226 where the light beam 225 travels straight through the space 205c between the polarization separation surface 205a and the total reflection surface 205b. Is imaged with a lateral shift amount 227 equal to.

The amount of lateral shift 227 is determined by the polarization separation surface 205.
The distance 205c between the polarization splitting surface 205a and the total reflection surface 205b is set so as to be 1/2 of the distance between individual small light sources formed by only the light flux 224 reflected by a. Thus, in the vicinity of the second lens array 209, the individual small light sources due to the light beam 224 reflected by the polarization splitting surface 205a and the individual small light sources due to the light beam 225 reflected by the total reflection surface 205b are displaced by the lateral displacement amount 227. Quantity 2
27, the number of small light sources is equal to twice the number of light beams divided by the first lens array 204. If a secondary light source (not shown) including a plurality of individual small light sources is considered without distinguishing the small light source by the light beam 224 and the small light source by the light beam 225, this secondary light source occupies the second lens array 209. The area of each small light source using only the light beam 224 is the second area.
Is almost the same as the area occupied on the lens array 209. The number of the second lens arrays 209 is equal to the number of the small light sources included in the secondary light source, that is, the first lens array 204
Has twice the number of lenses included in the light source, and each lens corresponds to each small light source.

Here, the individual lenses on the first lens array 204 and the liquid crystal panel are in an optically conjugate relationship.
Since the light beams split by the first lens array 204 are superimposed on the liquid crystal panel, the liquid crystal panel is illuminated with a uniform light amount distribution. Therefore, the number of lenses of the second lens array 209 is
If the number of lenses is equal to 4, the first lens array 20
4 can be superimposed only insufficiently on the liquid crystal panel, and the number of lenses of the second lens array 209 is set to correspond to the small light source included in the secondary light source. By doubling the number of lenses of the array 204, the light beams divided by the first lens array 204 can be efficiently and correctly superimposed on the liquid crystal panel.

Among the small light sources included in the secondary light sources formed on the second lens array 209, a lens corresponding to one of the small light sources formed by the light beam 224 or the light beam 225 is selected. By providing the half-wave plate 209a, the polarization direction of the small light source provided with the half-wave plate 209a is converted to the polarization direction of the small light source not provided with the half-wave plate 209a. The polarization directions of the light sources can be made uniform. Therefore, the luminous flux emitted from all the small light sources can be used very efficiently for illuminating the liquid crystal panel.

In FIG. 2, a half-wave plate 209a is provided on the side of the small light source formed by the light beam 225.
The small light source for providing the wave plate 209a may be either the light beam 224 or the small light source formed by the light beam 225, but when applied to the small light source formed by the light beam 225,
This is further preferable because it has the effect of correcting the optical path difference between the light beam 224 transmitted through the polarization separation surface 205a and the light beam 225 reflected by the polarization separation surface 205a. Further, the liquid crystal panel can be illuminated with a uniform light amount by the action of the optical integrator.

Further, by constructing a polarization conversion optical system with a polarization splitting surface and a total reflection surface, an inexpensive and compact illumination optical system which is easy to manufacture is realized. As described above, the half-wave plate is arranged near the second lens array constituting the optical integrator, and the polarization conversion optical system is arranged between the first and second lens arrays. The space occupied by the conversion optics and the optical integrator can be shared, and the area occupied by the secondary light source can be reduced, and the luminous flux from the light source can be used very efficiently for illuminating the liquid crystal panel, resulting in bright and uniform illuminance. A projection image of the distribution is obtained, and a compact liquid crystal projector in which the illumination optical system is downsized even in a direction perpendicular to the main optical axis direction is realized.

As shown in FIG. 3, the polarization beam splitter 3
If the shape of 05 is composed of a plurality of right angle prisms, the weight of the polarization conversion optical system can be reduced. As the size of the rectangular prism, a size of about 40 mm on a side is a preferable size because it is easy to process, but if further weight reduction is required,
Smaller right angle prisms may be used.

FIG. 4 is a block diagram of a main part of an illumination optical system according to a fourth embodiment of the present invention. In FIG. 4, a randomly polarized light beam emitted from a light source 401 is reflected by a reflector 402 and an unnecessary wavelength region is cut by an IR-UV cut filter 403, and then a first lens array 404 constituting an optical integrator Incident on. The light beam from the light source is split into a plurality of light beams by the first lens array 404 and is incident on the calcite plate 405, and is separated into two light beams 424 and 425 of two linearly polarized components orthogonal to each other by a birefringence effect. Calcite 5
Light beam 424 and light beam 4 separated by the double refraction
Numerals 25 form the same number of small light sources as the number of light beams divided by the first lens array 404 in the vicinity of the second lens array 409 due to the image forming action of the first lens array 404.

The second lens array 409 has a number of lenses equal to the number of small light sources formed by the light beams 424 and 425, that is, twice as many lenses as the first lens array 404. Corresponds to each small light source. The lens on the second lens array 409 corresponding to the small light source formed by the light beam 425 has 1 /
A two-wavelength plate 409 a is provided, and the polarization direction of the small light source formed by the light beam 425 is converted to the polarization direction of the small light source formed by the light beam 424. For this reason, the polarization directions of all the small light sources are aligned with the directions required for illumination of the liquid crystal panel,
The light beam from the light source 401 can be used very efficiently for illuminating the liquid crystal panel. Further, the liquid crystal panel can be illuminated with a uniform light amount by the action of the optical integrator.

Further, the use of calcite having a birefringent action provides a compact illumination optical system having a very simple configuration with a small number of parts. As described above, the half-wave plate is arranged near the second lens array constituting the optical integrator, and the first and second lens arrays are arranged between the first and second lens arrays using calcite having a birefringent action in the polarization conversion optical system. By arranging them, the illumination optical system can be reduced in size with a simple configuration, and a compact liquid crystal projector capable of obtaining a bright and uniform projection image with an illuminance distribution is realized. In the case of this embodiment, calcite was used as the birefringent material.
A birefringent material such as DP, ADP, liquid crystal, or polycarbonate having an internal stress and having a birefringence effect may be used.

FIG. 5 is a diagram showing a main part of an illumination optical system according to a fifth embodiment of the present invention. In FIG. 5, a Wollaston prism made of calcite having a birefringent function after a randomly polarized light beam emitted from a light source 501 is reflected by a reflector 502 and cut off unnecessary wavelength regions by an IR-UV cut filter 503. 505. The randomly polarized light beam incident on the Wollaston prism 505 is separated into two light beams having linear polarization components that travel in different directions and are orthogonal to each other, and the first lens array 50 that forms an optical integrator.
4 is incident. The first lens array 504 divides the light beam from the light source into the light beams of the number of lenses included in the first lens array 504, and forms an image near the second lens array 509 constituting the optical integrator to form a small light source. .

However, two light beams having linear polarization components orthogonal to each other are incident on the first lens array 504 at mutually different incident angles, so that light beams having different image forming positions in the vicinity of the second lens array 509 are different. 524 and luminous flux 52
It becomes 5. Therefore, the number of small light sources that is twice the number of lenses included in the first lens array 504 is formed in the vicinity of the second lens array 509, and the number of small light sources is formed on the second lens array 509 corresponding to each small light source. A lens is formed. A lens on the second lens array 509 corresponding to the small light source formed by the light beam 525 has a half-wave plate 509
a is given, and the polarization direction of the small light source formed by the light beam 525 is converted to the polarization direction of the small light source formed by the light beam 524. For this reason, the polarization directions of all the small light sources are aligned with the directions necessary for illumination of the liquid crystal panel, and the luminous flux from the light source 501 can be used very efficiently for illumination of the liquid crystal panel.

By arranging the half-wave plate in the vicinity of the second lens array constituting the optical integrator and arranging the Wollaston prism on the light source side of the first lens array as described above, the illumination optical system can be realized. With a simple configuration, a compact liquid crystal projector that can be downsized particularly in a direction perpendicular to the main optical axis of the illumination optical system and that can obtain a bright and uniform projection image with an illuminance distribution is realized.

The same effect can be obtained by disposing the Wollaston prism on the liquid crystal panel side of the first lens array. In the case of the present embodiment, calcite was used as the birefringent material of the Wollaston prism, but a birefringent material such as KDP, ADP, liquid crystal, and polycarbonate having an internal stress and having a birefringent action may be used. Instead of the Wollaston prism, a Rochon prism made of such a birefringent material may be used.

[0030]

As described above, according to the first aspect of the present invention, a half-wave plate and a polarization conversion optical system are provided near the second lens array of the optical integrator.
It is arranged closer to the light source than the lens array of (1), and polarization-separation can be performed in a space-saving direction in the direction perpendicular to the main optical axis of the illumination optical system by using the imaging function of the first lens array, so that the illumination optical system is downsized. Is done. Also, by disposing the polarization conversion optical system on the liquid crystal panel side of the first lens array, the polarization conversion optical system and the optical integrator occupy the same space, so that the illumination optical system extends in the main optical axis direction of the illumination optical system. It is downsized.

Further, according to the second aspect of the invention, the second
The number of lenses included in the first lens array is twice as large as the number of lenses included in the first lens array, and only half of the lenses are provided with a half-wave plate, whereby the first lens array after the polarization conversion is performed. Can be correctly formed on the liquid crystal panel, so that a bright and uniform projected image with high efficiency can be obtained. In addition, 請
According to the third aspect of the present invention, the polarization conversion is performed by using the optical path difference between the polarization splitting surface and the total reflection surface, so that the polarization conversion optical system can be easily manufactured and also compact. According to the fourth aspect of the present invention, even if a birefringent material is used, the polarization conversion optical system can be reduced in size and can have a simple configuration.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a main part configuration diagram of an illumination optical system according to a second embodiment of the present invention;

FIG. 3 is a main part configuration diagram of an illumination optical system according to a third embodiment of the present invention.

FIG. 4 is a main part configuration diagram of an illumination optical system according to a fourth embodiment of the present invention;

FIG. 5 is a main part configuration diagram of an illumination optical system according to a fifth embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 101 light source 102 reflector 103 IR-UV cut filter 104 first lens array 105 polarization beam splitter 105a polarization separation surface 105b total reflection surface 105c glass member 106 liquid crystal panel 107 liquid crystal panel 108 liquid crystal panel 109 second lens array 109a 1/2 wavelength Plate 110 Dichroic mirror 111 Dichroic mirror 112 Total reflection mirror 113 Field lens 114 Field lens 115 Field lens 116 Total reflection mirror 117 Total reflection mirror 118 Relay optical system 119 Relay optical system 120 Dichroic prism 121 Projection lens 124 Light flux 125 Light flux 201 Light source 202 Reflector 203 IR-UV cut filter 204 First lens array 205 Polarized beam split 205a polarization separation surface 205b total reflection surface 205c interval 209 second lens array 209a 波長 wavelength plate 224 light flux 225 light flux 226 optical path 227 lateral shift amount 305 polarization beam splitter 401 light source 402 reflector 403 IR-UV cut filter 404 first lens Array 405 Calcite plate 409 Second lens array 409a 1/2 wave plate 424 Light beam 425 Light beam 501 Light source 502 Reflector 503 IR-UV cut filter 504 First lens array 505 Wollaston prism 509 Second lens array 509a 1/2 wave plate 524 luminous flux 525 luminous flux

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-2899387 (JP, A) JP-A-7-120753 (JP, A) JP-A-6-265887 (JP, A) JP-A-61-1986 90584 (JP, A) JP-A-5-107505 (JP, A) JP-A-1-265206 (JP, A) JP-A-1-265228 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) G02F 1/13 G02F 1/1335

Claims (4)

(57) [Claims] 1. A light source, an illumination optical system, and the illumination optical system
A liquid crystal projector having a liquid crystal panel illuminated by the first lens array and the first lens array in order from the light source.
Optical integrator consisting of a second lens array
Data and random polarized light emitted from the light source.
A polarization conversion optical system that converts the light into polarized light in the light direction , a half-wave plate disposed near the second lens array of the optical integrator,
A liquid crystal projector characterized by being disposed on the liquid crystal panel side of the lens array of (1) and on the light source side of the second lens array. 2. The liquid crystal projector according to claim 1, wherein said second lens array has twice as many lenses as said first lens array. . 3. The liquid crystal projector according to claim 1, wherein the polarization conversion optical system uses a polarization splitting surface and a total reflection surface. 4. The liquid crystal projector according to claim 1, wherein said polarization conversion optical system uses a birefringent material.