JP2000162592A - Projection type picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively modulate light from a light source and to display a bright and even picture by forming a light source image by a light source image forming optical system so that the pixel distribution of a liquid crystal panel may be distribution enlarged in a ratio different between two perpendicular directions and forming an image by an image-formation optical system so that the distribution may agree with the pixel distribution of the liquid crystal panel in two cylindrical lens arrays. SOLUTION: The respective lens cells of a 1st lens array 32a form the light from the light source 31 into the images on the corresponding lens cells of a 2nd lens array 32b. The light source images are formed on the respective lens cells of the lens array 32b, and the lens array 32b becomes a secondary light source in a surface state where plural light source images are two- dimensionally arrayed. The respective lens cells of the lens array 32b are set to guide the transmitted light to the entire surface of the liquid crystal panel 37. The light from the light source 31 made incident on the respective lens cells of the lens array 32a is temporarily individually formed into the images as the light source images, and then superposed each other on the panel 37.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type image display apparatus for displaying an image by modulating and projecting light from a light source, and more particularly, to temporarily form light from a light source as a plurality of light source images. The present invention relates to a projection type image display device in which light of these light source images is formed by a microlens array on each pixel of a modulation liquid crystal panel.

[0002]

2. Description of the Related Art A projection type image display apparatus which displays an image by modulating and projecting light from a light source is used as a projection television or a data projector. In general,
The light is modulated by a liquid crystal panel. A liquid crystal panel has a large number of pixels arranged two-dimensionally, and performs polarization modulation of incident light at each pixel, thereby modulating light by causing a change in the intensity distribution of polarized light to the converted light. . The polarization conversion of each pixel is individually controlled in accordance with the image signal, and the degree of polarization conversion differs for each pixel, which causes a difference in the amount of polarized light after conversion between pixels. By projecting the polarized light having the difference in amount on the screen, an image having a difference in luminance, that is, an image is displayed.

It is desirable that the projection type image display device displays an image which is bright and has no unevenness in brightness. However, the light modulated by the liquid crystal panel is a polarization component having a polarization plane having a fixed direction, and a polarization component having a polarization plane perpendicular thereto is not used for projection. For this reason, if light is directly applied to the liquid crystal panel from a light source that emits light with a disordered plane of polarization, only an image with half the brightness of the light source can be displayed. Also, in general, the light source is composed of a substantially point-shaped lamp and a reflector, and the light emitted from the lamp is reflected and condensed by the reflector. The difference in strength tends to occur in the part. If this light flux is guided to the liquid crystal panel as it is, a difference occurs in the amount of light received by the liquid crystal panel between the portions on the panel, and the brightness of the displayed image becomes uneven.

In order to further modulate and project the light emitted from the light source, the light whose polarization plane is disordered is polarized and separated into two polarized lights whose polarization planes are perpendicular to each other. Are led to a liquid crystal panel. In this case, all light emitted from the light source is used for modulation, and the brightness of the image is doubled. Generally, polarization separation is performed by a polarization beam splitter (PB) that transmits one of polarization components whose polarization planes are perpendicular to each other and reflects the other.
The polarization conversion is performed by a half-wave plate that rotates the plane of polarization by 90 °.

[0005] In order to make the intensity distribution of light applied to the liquid crystal panel uniform, an integrator is provided to temporarily form light from a light source as a plurality of light source images, and the light of each light source image is incident on the entire surface of the liquid crystal panel. It is also performed. The integrator is composed of two lens arrays, and forms light from the light source on each lens cell of the first lens array on a corresponding lens cell of the second lens array, and separates the light of the plurality of light source images respectively. Guide to the entire surface of the liquid crystal panel. Thus, the light of the central part and the light of the peripheral part of the light beam from the light source are mixed and applied to any part of the liquid crystal panel. As a result, there is no difference between the portions in the amount of light received by the liquid crystal panel, and an image with uniform brightness is displayed.

[0006] There is also used a configuration in which a PBS array and a half-wave plate are incorporated in an integrator so that light intensity uniformization and polarization conversion are performed at once.

In a liquid crystal panel, it is necessary to partition pixels in order to prevent light from adjacent pixels from being mixed.
A circuit component such as a TFT is provided to drive each pixel. The part where these partitions and circuit components are provided is called a black matrix, and each pixel is surrounded by the black matrix. Light does not enter the black matrix, or does not exit when it enters, and light incident on the black matrix cannot be used for projection. This also hinders the improvement of the brightness of the image.

A microlens array is arranged on the front surface of the liquid crystal panel, and light from the integrator is made to enter only the pixel openings avoiding the black matrix.
For example, Japanese Patent Application Laid-Open No. Hei 9-318904 discloses a method of improving the brightness of an image to be displayed by increasing light use efficiency.
It is proposed in Japanese Patent Application Laid-Open No. Hei 10-111472. Light from a plurality of adjacent light source images is incident on each microlens cell constituting the microlens array, and each microlens cell focuses the light on a plurality of adjacent pixels. One pixel is provided with light of a plurality of light source images via a plurality of microlens cells, and the light reception amounts of all the pixels are substantially uniform.

[0009]

Generally, a liquid crystal panel is
It is a rectangle having a length / width ratio of 3: 4, 9:16, or the like.
The pixels of the liquid crystal panel are used for forming a definition and color image.
The pixels are arranged in consideration of the quality of the displayed image such as the degree of overlap of the color lights, and therefore, the ratio of the arrangement pitch of the pixels in the vertical direction and the horizontal direction does not match the ratio of the vertical and horizontal lengths of the liquid crystal panel.

In order to guide the light from the light source to the entire surface of the liquid crystal panel without waste, it is necessary to make the lens cells of the first lens array of the integrator substantially similar in shape to the liquid crystal panel. Is set substantially equal to the aspect ratio of the liquid crystal panel. Therefore, the ratio of the vertical and horizontal arrangement pitch of the lens cells of the first lens array becomes equal to the ratio of the vertical and horizontal length of the liquid crystal panel. On the other hand, the micro lens cell needs to form a light source image formed by the integrator on each pixel, in other words,
The distribution of the light source image on the liquid crystal panel must match the distribution of the pixels.

However, since the ratio of the vertical and horizontal arrangement pitches of the lens cells of the first lens array is not equal to the ratio of the vertical and horizontal arrangement pitches of the pixels of the liquid crystal panel, the optical axis of each lens cell of the first lens array is set to the array surface. If the light from the light source is focused on the optical axis so as to be perpendicular to the optical axis, the distribution of the formed light source image does not match the distribution of the pixels.
Therefore, Japanese Patent Application Laid-Open No. 9-318904 and Japanese Patent Application Laid-Open
In Japanese Patent Application Laid-Open No. 111472, each lens cell of the first lens array is decentered, so that the image forming position of light transmitted through each lens cell is deviated so that the distribution of the light source image matches the distribution of pixels. . The micro lens array is
The light source image thus formed is re-imaged on the liquid crystal panel without changing the distribution.

However, it is not easy to form an eccentric lens cell, and considerable time is required to accurately produce a lens array having a desired eccentricity. For this reason, in the conventional configuration, it is difficult to improve the manufacturing efficiency of the lens array, which causes an increase in manufacturing cost. In addition, an optical system having a simple configuration instead of the integrator cannot be adopted as means for forming the light source images arranged two-dimensionally.

Further, in the projection type image display devices disclosed in the above publications, a transmissive liquid crystal panel is used, and the microlens array is not set so as to be compatible with the reflective liquid crystal panel. In a reflective liquid crystal panel, incident light and reflected light pass through the same optical path, so that the microlens array arranged on the front surface of the liquid crystal panel for the purpose of imaging light on pixels results in divergence of reflected light. In order to form an image of the divergent reflected light on the screen, an extremely large-diameter projection optical system is required.In the configuration using the conventional microlens array, the light modulated by the reflective liquid crystal panel is projected to form an image. Display is practically impossible.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a simple configuration in which a light from a light source can be modulated without waste and a bright and uniform image can be displayed. It is another object of the present invention to provide an image display device, and further to provide a projection type image display device capable of using both a transmission type and a reflection type as a liquid crystal panel for modulating light.

[0015]

In order to achieve the above-mentioned object, the present invention provides a light source and a light source for forming an image.
A light source image forming optical system that forms a plurality of light source images arranged in a two-dimensional manner, and a liquid crystal panel that has a large number of pixels arranged two-dimensionally and modulates light from the plurality of light source images incident on each pixel. In a projection type image display device including an imaging optical system that forms light from a plurality of light source images on pixels of a liquid crystal panel and a projection optical system that projects light modulated by the liquid crystal panel onto a screen, a light source image is formed. The forming optical system forms a plurality of light source images so that the distribution of the pixels of the liquid crystal panel is enlarged at different ratios in two perpendicular directions, and the imaging optical system has different focal lengths. It consists of two cylindrical lens arrays whose directions are orthogonal to each other, and forms light from a plurality of light source images so that the distribution coincides with the distribution of pixels of the liquid crystal panel.

In this device, the distribution of the plurality of light source images formed by the light source image forming optical system is different from the distribution of the pixels of the liquid crystal panel. That is, the light source image forming optical system does not have a function of making the distribution of the light source image coincide with the distribution of the pixels, and thus has a simpler configuration. The light of the light source image formed by the light source image forming optical system is re-imaged on the liquid crystal panel by the image forming optical system. Since the imaging optical system is composed of two cylindrical lens arrays and their focal lengths are different and the imaging directions are orthogonal, the distribution of the light source image on the liquid crystal panel is the same as that of the light source image formed by the light source image forming optical system. Vary from distribution. This makes it possible to make the distribution of the light source image on the liquid crystal panel coincide with the distribution of the pixels.

By changing the focal length of the two cylindrical lenses, the distribution of the light source image on the liquid crystal panel can be freely set. Therefore, even when a liquid crystal panel having a different pixel distribution is used, only the imaging optical system needs to be replaced with another one, and there is no need to replace the light source image forming optical system.

The two cylindrical lens arrays of the image forming optical system may be formed on the front and back surfaces of one medium, or a medium having a high refractive index and a low refractive index having a concave groove serving as a lens surface. It may be formed by bringing two media into close contact from opposite directions.

The two cylindrical lens arrays may be provided with a birefringent medium on one side of the lens surface, and act as a lens only for a predetermined polarization component. In this case, a combination with a reflection type liquid crystal panel becomes possible. An imaging optical system in which the distribution of the light source image on the reflective liquid crystal panel matches the distribution of pixels by setting the two cylindrical lens arrays to have a lens function with respect to light from the light source image forming optical system. Function is secured. On the other hand, the two cylindrical lens arrays have no lens function with respect to the polarized light, and the imaging optical system causes the reflected light from the reflective liquid crystal panel to travel straight. That is, light modulated by the reflective liquid crystal panel is not converted into divergent light by the imaging optical system, but can be directly projected by the projection optical system.

The light source image forming optical system comprises a lens array in which lens cells substantially similar in shape to the liquid crystal panel are two-dimensionally arranged, and a plurality of light source images are formed by forming light from a light source in each lens cell. May be formed. Further, the light source image forming optical system is composed of a rod-shaped member having a cross section substantially similar in shape to the liquid crystal panel, and a plurality of light sources are formed by reflecting light from a light source imaged on the end of the rod-shaped member on the wall surface of the rod-shaped member. A light source image may be formed.

The former has a configuration similar to that of the conventional integrator, and the latter has an extremely simple configuration as compared with the integrator. In any light source image forming optical system, the surface receiving light from the light source is substantially similar to the liquid crystal panel. Therefore, it is easy to guide all light transmitted through that surface to the entire surface of the liquid crystal panel. Therefore, the light from the light source can be given to the liquid crystal panel without loss, and the distribution of the light source image can be prevented from changing before reaching the imaging optical system.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a projection type image display device (hereinafter, also simply referred to as a projection display device) of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 shows the overall configuration of the optical system of the projection type image display device 1 according to the first embodiment. The projection display device 1 is a single-panel color image display device that modulates red (R) light, green (G) light, and blue (B) light with one liquid crystal panel.

The projection display device 1 includes a light source 11, a kaleidoscope 12, a condenser lens 13, and a relay optical system 1.
4, PBS prism array 15, half-wave plate 16, total reflection mirror 17, field lens 18, diffraction grating 1
9, micro lens array 20, transmission type liquid crystal panel 2
1 and a projection optical system 22. LCD panel 2
1 is a rectangle having a ratio of the length of the long side to the length of the short side of 4: 3.

The light source 11 comprises a metal halide lamp 11a and an elliptical reflector 11b. Lamp 11a
Emits white light whose polarization plane is disordered and includes the entire wavelength in the visible region. The lamp 11a is disposed on a first focal point of the reflector 11b, and the reflector 11b is connected to the lamp 11a.
Is reflected and collected at the second focal point.

The kaleidoscope 12 has a rectangular cross section having a ratio of 4: 3 in a direction corresponding to the long side and the short side of the liquid crystal panel 21. The entrance surface 12a of the kaleidoscope 12 is located on the second focal point of the reflector 11b, and is substantially conjugate with the lamp 11a. The light from the lamp 11a
An image is formed at the center of a, and efficiently enters the kaleidoscope. The light that has entered the kaleidoscope 12 repeats total reflection within the kaleidoscope 12 and emerges from the exit surface 12b in a uniform light amount distribution.

The condenser lens 13 is arranged close to the exit surface 12b of the kaleidoscope 12, and forms an image of the light emitted from the kaleidoscope 12 on the pupil plane of the relay optical system 14. Incident surface 12a of callide scope 12
And the pupil plane of the relay optical system 14 is substantially conjugate. A plurality of light source images are formed on the pupil plane of the relay optical system 14 at positions corresponding to the number of reflections in the kaleidoscope 12.

The relay optical system 14 has two convex lenses 14
The lens 14a on the incident side makes the light from the kaleidoscope 12 parallel between the lenses 14a and 14b. In order to increase the parallelism of light, an aspheric lens is used as the incident side lens 14a. The exit surface 12b of the kaleidoscope 12 and the liquid crystal panel 21 are substantially conjugated by the relay optical system 14.
Is similar in shape to the liquid crystal panel 21, so that light is uniformly and efficiently guided to the liquid crystal panel 21.

The pupil of the relay optical system 14 is located between the lens 14a and the lens 14b.
The next light source image is also formed on the pupil plane between the lenses 14a and 14b. The PBS prism array 15 is arranged on the pupil plane of the relay optical system 14. The PBS prism array 15 has a band-shaped PBS film 15a that transmits P-polarized light and reflects S-polarized light. The PBS films 15a are arranged at equal intervals in parallel to each other at an angle of 45 ° with respect to the optical axis of the relay optical system 14. The half-wave plate 16 is provided on the lens 14b side of the PBS prism array 15 every other PB.
It is provided to face the S film 15a.

The light transmitted through the incident side lens 14a of the relay optical system 14 forms an image on the PBS prism array 15 and is separated into P polarized light transmitted through the PBS film 15a and S polarized light reflected by the PBS film 15a. You. PBS
The P-polarized light transmitted through the film 15a is incident on the half-wave plate 16, and is converted into S-polarized light while transmitting the P-polarized light.
4b. On the other hand, the S-polarized light reflected by the PBS film 15a is reflected again by the adjacent PBS film 15a, passes through the half-wave plate 16, and enters the lens 14b. Therefore, all light incident on the lens 14b, that is, light exiting the relay optical system 14, becomes S-polarized light.

Even when a plurality of light source images are formed by the kaleidoscope 12, the relay optical system 14 and the PBS
By combining with the prism array 15, there is no need to provide a large prism, and the device can be made small and lightweight.

FIG. 2 shows a light source image distribution due to light from the light source 11 formed on the PBS prism array 15. In FIG. 2, the light source image shown by the solid line is due to S-polarized light, the light source image shown by the broken line is due to P-polarized light, and the latter light is later converted to S-polarized light. The cross section of the kaleidoscope 12 is a rectangle having a ratio of 4: 3 similar to the liquid crystal panel 21, and polarization separation is performed in the long side direction of the cross section of the kaleidoscope 12 by the PBS prism array 15. The ratio of the pitch in the direction corresponding to the long side and the short side of the liquid crystal panel 21 is 2: 3.

The total reflection mirror 17 reflects light from the relay optical system 14 and guides the light to the field lens 18. The total reflection mirror 17 is provided to reduce the size of the entire configuration of the projection display device 1, and includes a field lens 18, a liquid crystal panel 21, a projection optical system 22, and the like arranged on the optical axis of the relay optical system 14. Alternatively, the total reflection mirror 17 may be omitted.

The field lens 18 includes a liquid crystal panel 21
So that all light transmitted through the projection optical system 22
The light from the relay optical system 14 is directed in a direction substantially perpendicular to the liquid crystal panel 21. The diffraction grating 19 diffracts white light from the relay optical system 14 transmitted through the field lens 18 and decomposes the light into three colors of R, G, and B.

The micro lens array 20 forms an image of the incident light on the liquid crystal panel 21. That is, the pupil plane of the relay optical system 14 and the liquid crystal panel 21 are substantially conjugate. The three colors of light of R, G, and B separated by the diffraction grating 19 travel in slightly different directions due to the difference in the diffraction angle, and are imaged on different pixels of the liquid crystal panel 21 by the microlens array 20.

The projection optical system 22 projects the light transmitted through each pixel of the liquid crystal panel 21 and modulated onto a screen (not shown). The projected light forms an image on a screen to display a color image.

The liquid crystal panel 21 has a large number of two-dimensionally arranged three types of pixels for modulating R light, G light and B light. Each pixel is a rectangle whose short side is approximately 1/3 of the long side, and the long side and the short side are aligned.
The three types of pixels are alternately arranged in the short-side direction, and light representing one point of an image is modulated by three adjacent pixels in the short-side direction. Hereinafter, a set of three adjacent pixels in the short side direction is referred to as a pixel unit.

The pixel unit is substantially square, and the liquid crystal panel 2
1 are arranged at equal pitches in the long side direction and the short side direction. Therefore, the distribution of the light source image formed in the pupil plane of the relay optical system 14 by the kaleidoscope 12 and the condenser lens 13 in FIG. The light source image formed on the pupil plane of the relay optical system 14 has a distribution obtained by enlarging the distribution in pixel units at different ratios in the long side direction and the short side direction of the liquid crystal panel 21.
In order to correct this difference in distribution and efficiently guide the light of the light source image in pixel units, the imaging capability of the microlens array 20 is as follows:
The liquid crystal panel 21 is set differently in the long side direction and the short side direction.

FIG. 3 shows the microlens array 20.
The microlens array 20 includes two cylindrical lens arrays 20a and 20b formed on separate plate members.
Consisting of The lens arrays 20a and 20b are arranged so that the arrangement direction (imaging direction) of the respective cylindrical lenses is vertical. Micro lens array 20
Is such that the arrangement direction of the cylindrical lenses of the lens array 20a coincides with the long side direction of the liquid crystal panel 21, the arrangement direction of the cylindrical lenses of the lens array 20b coincides with the short side direction of the liquid crystal panel 21, and On the liquid crystal panel 21 side. The width of the cylindrical lenses of the lens arrays 20a and 20b is an integral multiple of the length of one side of the pixel unit.

The light source image on the pupil plane of the relay optical system 14 in which the ratio of the arrangement pitch in the direction corresponding to the long side and the short side of the liquid crystal panel 21 is 2: 3 is 1: 1 on the liquid crystal panel 21. In order to make the arrangement pitch ratio equal to the arrangement pitch in pixel units in both the long side direction and the short side direction, the focal length of the cylindrical lens of the lens array 20b is set to the lens array 20a.
Is set shorter than the focal length of the cylindrical lens. The distribution of the light source image is corrected based on the difference in the focal length, and the distribution of the light source image on the liquid crystal panel 21 matches the distribution in pixel units, so that light can be efficiently guided to the pixels.

In a cylindrical lens formed corresponding to the size of a pixel unit of a liquid crystal panel, an increase in the F value is inevitable, and a light source image formed on a pixel is blurred due to the influence of diffraction. . However, in the projection display device 1, the direction of color separation by the diffraction grating 19 is set to the short side direction of the pixel of the liquid crystal panel 21, and the lens array 20 b having an image forming ability in the short side direction of the pixel is brought close to the liquid crystal panel 21. By placing it and setting its focal length short,
The F value of the microlens array 20 is reduced in the short side direction of the pixel. Accordingly, blurring of the light source image in the short side direction of the pixel is reduced, and light can be reliably contained in the pixel.

As described above, in the single-panel type color image display device, it is preferable that the direction of color separation coincides with the image forming direction of the cylindrical lens array near the liquid crystal panel. Note that by increasing the width of the cylindrical lenses of the lens arrays 20a and 20b, the F value of the microlens array 20 can be reduced to reduce blur.

FIG. 4 shows the overall configuration of the optical system of the projection type image display device 2 according to the second embodiment. This projection display device 2
Is a single-panel color image display device that modulates R, G, and B light with one liquid crystal panel. However, in the projection display device 2, light is modulated by a reflective liquid crystal panel instead of a transmissive liquid crystal panel. The projection display device 2 includes a light source 31, an integrator 32, a PBS prism 33, and a half-wave plate 3.
4, dichroic PBS prism 35, micro lens array 36, reflection type liquid crystal panel 37, polarizing plate 38a,
38b, and a projection optical system 39. The liquid crystal panel 37 is a rectangle having a ratio of the length of the long side to the length of the short side of 4: 3.

The light source 31 is a metal halide lamp 31a,
It comprises a parabolic reflector 31b and a UV cut filter 31c. The lamp 31a emits white light having a disordered polarization plane and including the entire wavelength in the visible region. Lamp 31a
Is disposed at the focal point of the reflector 31b, and the reflector 31b reflects the light emitted from the lamp 31a to form a parallel light beam. The UV cut filter 31c is a reflector 31
The wavelength in the ultraviolet region is removed from the light incident from b to leave only the wavelength in the visible region.

The integrator 32 includes first and second lens arrays 32a and 32b in each of which a plurality of lens cells are two-dimensionally arranged. First lens array 32a
Each lens cell is set to a rectangle similar to the liquid crystal panel 37, and the optical axis of each lens cell is perpendicular to the panel surface. The second lens array 32b has twice as many lens cells as the first lens array 32a, and one lens cell of the lens array 31a has the lens array 3
A pair of adjacent lens cells 2b correspond to each other.

Each lens cell of the first lens array 32a focuses light from the light source 31 on a corresponding lens cell of the second lens array 32b. Second lens array 3
A light source image is formed in each lens cell 2b, and a lens array 32b is a planar 2D array in which a plurality of light source images are two-dimensionally arranged.
The next light source. Each lens cell of the lens array 32b is set to guide transmitted light to the entire surface of the liquid crystal panel 37.

That is, the first lens array 32a and the liquid crystal panel 37 are substantially conjugate, and the second lens array 32
b and the light source 31 are substantially conjugate, and the first lens array 3
The light from the light source 31 incident on each lens cell 2a is once formed individually as a light source image and then overlaps on the liquid crystal panel 37.

The PBS prism 33 is composed of a triangular prism 33a having a right-angled isosceles triangle in cross section, and a parallel flat plate 33b joined to its slope. Prism 33a and flat plate 33b
PB that transmits P-polarized light and reflects S-polarized light
An S film 33c is formed, and the other surface of the flat plate 33b is a total reflection surface 33d. The lens arrays 32a and 32b of the integrator 32 are arranged to face two orthogonal surfaces of the prism 33a.

The light from the light source 31 that has passed through the lens cells of the first lens array 32a enters the PBS film 33c, the S-polarized light contained in the light is reflected by the PBS film 33c, and the P-polarized light is reflected by the PBS film 33c. Through. Thereby, polarization separation is performed. The S-polarized light reflected by the PBS film 33c is incident on one of the two lens cells forming a pair of the second lens array 32b, and forms an image. PBS
The P-polarized light transmitted through the film 33c is reflected by the total reflection surface 33d, enters the other of the two lens cells forming a pair of the lens array 32b, and forms an image.

The half-wave plate 34 is provided with a lens array 32b.
Is provided on the side of the PBS prism 33, and is disposed corresponding to the lens cell on which the P-polarized light is incident. 1/2 wave plate 3
4 converts the transmitted P-polarized light into S-polarized light, so that all light incident on the lens array 32b, that is, light exiting the integrator 32, becomes S-polarized light. However, a polarizing plate 38a for blocking P-polarized light is provided in the case where P-polarized light is mixed into light exiting the integrator 32 due to incomplete polarization separation or polarization conversion for some reason.

The polarization separation by the PBS prism 33 is the first
Is performed in the long side direction of the lens cell of the lens array 32a. Therefore, the light source image on the second lens array 32b has an arrangement pitch of a ratio of 2: 3 between the long side direction and the short side direction of the liquid crystal panel 37, similarly to the light source image of the projection display device 1 shown in FIG. Becomes

The dichroic PBS prism 35 has:
Three dichroic PBS membranes 35R, 35G, 35B
Are formed with a slight angle difference. The dichroic PBS film 35R selectively reflects the S-polarized R light, transmits other S-polarized light, and transmits all P-polarized light. Dichroic PBS membrane 35G
Is for reflecting S-polarized G light and transmitting S-polarized B light and P-polarized all-color light. Dichroic PB
The S film 35B reflects S-polarized B light and transmits all P-polarized light. The S-polarized white light incident on the prism 35 from the integrator 32 via the polarizing plate 38a is converted into the dichroic PBS films 35R, 35G, 35G.
The light is decomposed into R light, G light, and B light by B, and since there is an angle difference between the PBS films, the separated R light, G light, and B light are reflected in slightly different directions.

The dichroic PBS prism 35
Instead of three dichroic mirrors and one PBS
A prism may be provided. In that case, PBS
The prism is arranged at the position of the prism 35, and the three dichroic mirrors are arranged at a slight angle difference between the PBS prism and the integrator 32.

The micro lens array 36 forms an image of the incident light on the liquid crystal panel 37. That is, the second lens array 32 b of the integrator 32 and the liquid crystal panel 37
Is approximately conjugate. The three colors of light of R, G, and B separated by the dichroic PBS prism 35 travel in slightly different directions due to the difference in the reflection angle, and are imaged on different pixels of the liquid crystal panel 37 by the microlens array 36.

The pixels of the liquid crystal panel 37 correspond to the projection display device 1.
Are set similarly to the liquid crystal panel 21 of FIG. That is,
One pixel unit is composed of three rectangular pixels having a ratio of the long side to the short side of approximately 3: 1. The pixel unit is substantially square, and the pitch is equal in the long side direction and the short side direction of the liquid crystal panel 37. It is arranged in.

The R light, G light and B light are modulated by the liquid crystal panel 37 to change from S-polarized light to P-polarized light.
Each light reflected by the liquid crystal panel 37 is transmitted through the microlens array 36, is also transmitted through the dichroic PBS prism 35 that freely transmits P-polarized light, and is incident on the polarizing plate 38b. The polarizing plate 38b blocks S-polarized light and prevents S-polarized light such as stray light from entering the projection optical system 39. The projection optical system 39 projects the light incident from the polarizing plate 38b onto a screen (not shown), and the projected light forms an image on the screen to display a color image.

The micro lens array 36 is composed of two cylindrical lens arrays whose image forming directions are perpendicular to each other and whose focal lengths are different. The relationship between the focal lengths of the two cylindrical lens arrays and the positions of the two cylindrical lens arrays with respect to the liquid crystal panel 37 is as described in the first embodiment, and a light source image having a distribution different from the pixel unit of the liquid crystal panel 37 formed by the integrator 32 is obtained. An image is formed on the liquid crystal panel 37 in accordance with the distribution in pixel units.

The liquid crystal panel 37 is of a reflection type, and the microlens array 36 is arranged at a position where light incident on the liquid crystal panel 37 and light reflected from the liquid crystal panel 37 pass.
If the microlens array 36 at such a position acts as a lens with respect to the reflected light, the reflected light diverges, and an extremely large projection optical system 39 is required. become unable. Therefore, the microlens array 36 needs to act as a lens only for light incident on the liquid crystal panel 37. In order to realize this, the projection display device 2 uses a birefringent material as a medium of the two cylindrical lens arrays.

Microlens array 36 and liquid crystal panel 3
FIGS. 5 and 6 schematically show the configuration of FIG. 7 and the effect of the microlens array 36 on incident light and reflected light. FIG. 5 shows the relationship between the microlens array 36 and the light incident on the liquid crystal panel 37, and FIG. 6 shows the relationship between the microlens array 36 and the reflected light from the liquid crystal panel 37. In these figures, (a) is a cross-sectional view along the long side of the liquid crystal panel 37, and (b) is a cross-sectional view along the short side. Reference numerals 37R, 37G, and 37B represent pixels that modulate R light, G light, and B light, respectively.

The first component of the micro lens array 36
The cylindrical lens array 36a is formed by closely adhering a medium A1 having no birefringence and a medium A2 having birefringence, and the second cylindrical lens array 36b is a medium having no birefringence. B1 is formed by closely adhering a medium B2 having birefringence. The interface between the medium A1 and the medium A2 is a lens array surface having a curvature in the short side direction of the liquid crystal panel 37, and the medium B1 and the medium B2
Is a lens array surface having a curvature in the long side direction of the liquid crystal panel 37.

Although the refractive indices of the mediums A2 and B2 for the S-polarized light and the P-polarized light are different, the refractive index of the medium A2 for the P-polarized light is set to be equal to the refractive index of the medium A1.
The refractive index of the medium B2 for polarized light is set equal to the refractive index of the medium B1. Further, the projection display device 2 is set such that the polarization planes of the S-polarized light and the P-polarized light correspond to the short side direction and the long side direction of the liquid crystal panel 37, respectively.

Therefore, the first cylindrical lens array 36a has a lens function with respect to the S-polarized light, and the image forming direction is the short side direction of the liquid crystal panel 37. The second cylindrical lens array 36b has a lens function for S-polarized light, and the image forming direction is the long side direction of the liquid crystal panel 37. Further, neither the first nor the second cylindrical lens array 36a, 36b has a lens function for P-polarized light.

One cylindrical lens of the first lens array 36a forms light from a light source image adjacent in the short side direction of the liquid crystal panel 37 on a pixel in a pixel unit adjacent in the short side direction (FIG. 5). (B)). Second lens array 36b
The one cylindrical lens forms light from a light source image adjacent in the long side direction of the liquid crystal panel 37 on pixels in pixel units adjacent in the long side direction (FIG. 5A). At this time,
The light from the light source is color-separated in the long side direction of the liquid crystal panel 37, and the R light, the G light, and the B light
Images are formed on 7R, 37G, and 37B, respectively.

On the other hand, since the reflected light from the liquid crystal panel 37 is P-polarized light, the second lens array 36b is also the first polarized light.
Also travels straight through the lens array 36a (FIG. 6). Thus, the reflected light transmitted through the microlens array 36 is
The light enters the projection optical system 39 without widening, and the diameter of the projection optical system 39 may be small.

As the mediums A2 and B2 having birefringence, any material may be used. Here, liquid crystal is used.
Various liquid crystal materials having different refractive indices have been developed, and the degree of freedom of the combination of the refractive indices with the media A1 and B1 is extremely wide. Further, the microlens array 36 can be easily manufactured only by processing the surfaces of the media A1 and B1 and filling the liquid crystal between the media A1 and B1 and the flat plate C. In addition, since the narrow cylindrical lens arrays 36a and 36b having a curvature in only one direction are manufactured, it is extremely easy to align the liquid crystal.

An organic film may be used as a birefringent material. Pressing makes it easy to adhere to a solid medium. Further, it is also possible to form an organic film by enclosing an organic monomer between two solid media, aligning the orientation, and polymerizing with an ultraviolet ray or heat.

Another example of the structure of the microlens array 36 is shown in FIGS. The micro lens array 36 of FIG.
Has concave lens array surfaces formed on the upper and lower surfaces of a solid medium AB1, and flat plates C1 and C2 are arranged opposite to both surfaces, and liquid crystal is birefringent between the medium AB1 and the flat plates C1 and C2. It is filled as media A2 and B2. The medium AB1 and the medium A2 form a first cylindrical lens array 36a, and the medium AB1 and the medium B
2 constitutes a second cylindrical lens array 36b. The refractive index (Nd) of the medium AB1 is 1.5, and the refractive index of the medium A2 for S-polarized light and P-polarized light is 1.
The refractive indexes of the medium B2 for S-polarized light and P-polarized light are 1.7 and 1.5, respectively.

The microlens array 36 shown in FIG. 8 includes a solid medium A1 having a concave lens array surface formed on the lower surface,
Solid medium B1 having a concave lens array surface formed on the upper surface
Are arranged to face each other, and a liquid crystal AB
It was filled as 2. The medium A1 and the medium AB2 form a first cylindrical lens array 36a, and the medium B1 and the medium AB2 form a second cylindrical lens array 36b. Medium A1, B1
Has a refractive index of 1.5, and the refractive index of the medium AB2 with respect to S-polarized light and P-polarized light is 1.7 and 1.5, respectively.

In the microlens array 36 of FIG. 9, solid media A1 and B1 each having a concave lens array surface formed on the upper surface thereof are arranged facing each other, and a flat plate C1 is arranged facing the upper surface of the medium A1. Liquid crystal is filled between the three as the birefringent media A2 and B2. The first cylindrical lens array 36a is formed by the medium A1 and the medium A2.
And the medium B1 and the medium B2 form a second cylindrical lens array 36b. Medium A1,
The refractive index of B1 is 1.5, and the refractive indices of the mediums A2 and B2 for S-polarized light and P-polarized light are 1.7 and 1.5, respectively.

In the microlens array 36 of FIG. 10, solid media A1 and B1 each having a convex lens array surface formed on the lower surface thereof are arranged to face each other, and a flat plate C2 is arranged to face the lower surface of the medium B1. Further, the upper surface of the medium B1 is １ ／
A wave plate D is provided, and the liquid crystal is birefringent between the medium A1 and the half-wave plate D and between the medium B1 and the flat plate C2.
2, B2. Medium A1 and medium A
2 constitutes a first cylindrical lens array 36a, and the medium B1 and the medium B2 constitute a second cylindrical lens array 36b. Medium A1, B
1 has a refractive index of 1.7, the refractive index of the medium A2 for S-polarized light and P-polarized light is 1.5 and 1.7, respectively, and the refractive index of the medium B2 for S-polarized light and P-polarized light is 1.7 and 1.5, respectively. It is.

The S-polarized incident light is applied to the first lens array 36.
After being converted into P-polarized light by passing through the half-wave plate D, the second lens array 36
The lens is acted on by b to enter a liquid crystal panel 37 (not shown). The reflected light converted into S-polarized light by the modulation by the liquid crystal panel 37 travels straight without receiving the lens action of the second lens array 36b, and is converted into P-polarized light by transmitting through the half-wave plate D. , First lens array 36a
It goes straight without receiving the lens action.

The specific refractive index shown here is merely a typical example, and other refractive indexes may be used as long as the magnitude relation is maintained. Generally, the refractive index of a medium such as glass, plastic, and liquid crystal is in the range of about 1.4 to 1.9, and there are many combinations of available media. Since the focal length of the first and second cylindrical lens arrays 36a and 36b is determined by the curvature of the lens array surface and the refractive index of the medium,
A medium having an appropriate refractive index may be selected in consideration of the curvature, and the curvature may be determined according to the refractive index of the medium.

The configuration of the microlens array 36 shown in FIGS. 7 to 10 can be applied to the projection display device 1 of the first embodiment using a transmission type liquid crystal panel. However, when used in combination with a transmissive liquid crystal panel, there is no point in using a medium having birefringence.
2. AB2 has no birefringence. In particular, in the configuration of FIG. 10, the media A2 and B2 may be air. Further, it is not necessary to provide the half-wave plate D.

The projection display devices 1 and 2 of the above two embodiments
Although the pixel units are arranged at equal pitches in the long side direction and the short side direction of the liquid crystal panel, the arrangement pitch ratio of the pixel units may be set arbitrarily. Further, the ratio of the length of the long side to the length of the short side of the liquid crystal panel is not limited to 4: 3. The focal lengths of the microlens array in two directions may be determined according to the ratio of the arrangement pitch in pixel units and the ratio of the lengths of the long side and the short side of the liquid crystal panel.

The present invention is also applicable to a three-plate type color image display device in which R, G and B lights are individually modulated by three liquid crystal panels. In that case, three micro lens arrays composed of two cylindrical lens arrays are provided corresponding to each liquid crystal panel. In the case of the three-panel type, one pixel constitutes one pixel unit, but the distribution of pixels of each liquid crystal panel is fine regardless of the ratio of the long side to the short side of the liquid crystal panel. Set in consideration of the quality of the displayed image such as the degree. On the other hand, the cross section of the kaleidoscope and the lens cells of the first lens array of the integrator are substantially similar in shape to the liquid crystal panel, and the light source image to be formed has a distribution corresponding to the ratio of the long side to the short side of the liquid crystal panel. This light source image is formed on a liquid crystal panel by a microlens array having different imaging capabilities in two perpendicular directions, so that the distribution of the light source image on the liquid crystal panel matches the distribution of pixels.

Specific values of various parameters of the micro lens array of the projection type image display device of the present invention will be described. The numerical values shown below do not necessarily correspond to the projection display devices 1 and 2 of the first and second embodiments in which the ratio of the length of the long side to the short side of the liquid crystal panel is 4: 3. Setting values in other configurations similar to these are also included. Further, in the following description, the short side direction means the short side direction of the liquid crystal panel or a direction corresponding thereto, and the same applies to the long side direction.

The arrangement pitches of the light source images formed by the kaleidoscope and the integrator in the short side direction and the long side direction are a1 and a2, respectively, The arrangement pitches in the side direction are b1 and b2, respectively. Further, distances from a light source image formed by a kaleidoscope or an integrator to a cylindrical lens array having an image forming ability in a short side direction and a long side direction of the micro lens array are c1 and c, respectively.
2. The distance from the cylindrical lens array having the imaging ability in the short side direction and the long side direction to the liquid crystal panel is d, respectively.
1, d2.

Further, the focal lengths of the cylindrical lens array having the imaging ability in the short side direction and the long side direction are set to f1, f
2. Let the radius of curvature of each cylindrical lens be r
1, r2, and the difference between the refractive indices of the two media constituting each are denoted by ΔNd1 and ΔNd2. For simplicity, c
1, c2, d1, and d2 are air-equivalent optical path lengths.

At this time, the following relational expression holds. d1 = b1 · c1 / a1 d2 = b2 · c2 / a2 f1 = c1 · d1 / (c1 + d1) f2 = c2 · d2 / (c2 + d2) r1 = f1 · ΔNd1 r2 = f2 · ΔNd2

Here, in the first setting example, a1 = 10.
0, a2 = 15.0, b1 = b2 = 0.03, c1 = 1
00.0. The unit is mm (the same applies hereinafter). At this time, c2 = 100.1, d1 = 0.300, d2 =
0.200, f1 = 0.299, f2 = 0.200, and ΔNd1 = ΔNd2 = 1.7−1.5 = 0.2, and r1 = 0.060 and r2 = 0.040 .

In the second setting example, the same distance relationship as in the first setting example is used, and ΔNd1 = ΔNd2 = 1.5−1.0 =
Set to 0.5, r1 = 0.150, r2 = 0.10
Set to 0.

In the third setting example, a1 = 12.0, a2
= 9.0, b1 = b2 = 0.03, and c1 = 100.0. At this time, c2 = 99.917, d1 = 0.25
0, d2 = 0.333, f1 = 0.249, f2 = 0.
332, and ΔNd1 = ΔNd2 = 1.5−1.0 =
Setting to 0.5, r1 = 0.125, r2 = 0.16
6 is assumed.

It is easy to form a cylindrical lens array having these values, and a microlens array can be manufactured with high precision.

[0083]

According to the projection type image display apparatus of the present invention, the function of making the light source image distribution coincide with the pixel distribution in the light source image forming optical system for forming a plurality of light source images arranged two-dimensionally. Therefore, the light source image forming optical system can have a simple configuration. Further, various liquid crystal panels having different pixel distributions can be used only by changing the imaging optical system, and it is not necessary to prepare a light source image forming optical system for each liquid crystal panel. Moreover, since the cylindrical lens array has an image forming ability only in one direction, its production is easy and its production efficiency is high. Also, when manufacturing various types of projection type image display devices having different pixel distributions of the liquid crystal panel, a large increase in manufacturing cost does not occur.

In a configuration in which two cylindrical lens arrays of an imaging optical system are formed by bringing two mediums having a low refractive index having a concave groove serving as a lens surface into close contact with a medium having a high refractive index from opposite directions. In addition, the range of choice of the medium is widened, and the imaging capability of the imaging optical system can be easily set by utilizing not only the curvature of the lens surface but also the difference in the refractive index of the medium. Further, as the central medium having a high refractive index, not only a solid but also a liquid medium such as a liquid crystal can be used.

In a configuration in which a medium having birefringence is provided in the two cylindrical lens arrays of the imaging optical system so that only a predetermined polarized light component acts as a lens, light can be modulated by a reflective liquid crystal panel. Thus, a high-definition image can be displayed by utilizing the characteristics of the reflective liquid crystal panel.

The light source image forming optical system is constituted by a rod-shaped member having a cross section substantially similar to the liquid crystal panel, and the light from the light source formed on the end of the rod-shaped member is reflected by the wall surface of the rod-shaped member to form a plurality of light-source images. In the projection type image display device that forms the light source image, since the light source image forming optical system is simple, the entire device can be reduced in size and weight, and the manufacturing cost of the device can be reduced. .

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an overall configuration of an optical system of a projection type image display device according to a first embodiment.

FIG. 2 is a diagram illustrating a distribution of a light source image formed by a calliscope and a condenser lens of the projection-type image display device according to the first embodiment.

FIG. 3 is a perspective view showing a microlens array of the projection type image display device according to the first embodiment.

FIG. 4 is a diagram illustrating an overall configuration of an optical system of a projection-type image display device according to a second embodiment.

FIG. 5 is a cross-sectional view schematically showing a configuration of a microlens array and a liquid crystal panel of a projection type image display device according to a second embodiment, and an action of the microlens array on light incident on the liquid crystal panel.

FIG. 6 is a cross-sectional view schematically showing a configuration of a microlens array and a liquid crystal panel of a projection-type image display device according to a second embodiment, and an action of the microlens array on light reflected from the liquid crystal panel.

FIG. 7 is a diagram illustrating another configuration of the microlens array of the projection-type image display device according to the second embodiment.

FIG. 8 is a diagram showing still another configuration of the microlens array of the projection-type image display device according to the second embodiment.

FIG. 9 is a diagram showing still another configuration of the microlens array of the projection-type image display device according to the second embodiment.

FIG. 10 is a diagram showing still another configuration of the microlens array of the projection-type image display device according to the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Projection type image display apparatus 11 Light source 12 Kaleidoscope (light source image forming optical system) 13 Condenser lens (light source image forming optical system) 14 Relay optical system 14a, 14b Relay lens 15 PBS prism array 15a PBS film 16 1/2 wavelength Plate 17 Total reflection mirror 18 Field lens 19 Diffraction grating 20 Micro lens array (imaging optical system) 20a, 20b Cylindrical lens array 21 Transmission liquid crystal panel 22 Projection optical system 2 Projection image display device 31 Light source 32 Integrator (light source image formation) Optical system) 32a, 32b Lens array 33 PBS prism 33c PBS film 33d Total reflection surface 34 1/2 wavelength plate 35 Dichroic PBS prism 35R, 35G, 35B Dichroic PBS film 36 Micro lens array (imaging optical system) 36a, 36b cylindrical lens array 37 the reflective liquid crystal panels 37R, 37G, 37B pixels 38a, 38b polarizing plate 39 projection optical system A1, A2, B1, B2, AB1, AB2 medium D 1/2 wave plate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03B 21/14 G03B 21/14 A G09F 9/00 360 G09F 9/00 360D F-term (Reference) 2H052 BA02 BA03 BA09 BA14 2H088 EA13 EA15 EA16 HA10 HA13 HA15 HA21 HA24 HA25 HA28 MA03 MA04 MA20 2H091 FA05X FA11Z FA14Z FA19Z FA24Z FA26X FA26Z FA29Z FA41Z FD02 KA01 LA11 LA12 LA15 LA16 LA18 MA07 5G435 FF01 BB12 FF15 BB01 FF02 GG03 GG04 GG08 GG16 GG28

Claims (6)

[Claims] 1. A light source comprising: a light source; a light source image forming optical system that forms a plurality of two-dimensionally arranged light source images by forming light from the light source; and a plurality of two-dimensionally arranged pixels. A liquid crystal panel that modulates light from the plurality of light source images incident on each pixel, an imaging optical system that forms light from the plurality of light source images on pixels of the liquid crystal panel, and the liquid crystal panel. In a projection-type image display apparatus including a projection optical system that projects modulated light onto a screen, the light source image forming optical system has a distribution obtained by enlarging a distribution of pixels of the liquid crystal panel at different ratios in two perpendicular directions. As described above, the plurality of light source images are formed, and the imaging optical system includes two cylindrical lens arrays having different focal lengths and orthogonal imaging directions, and has a distribution matching the distribution of pixels of the liquid crystal panel. As above Projection type image display apparatus characterized by focusing the light from the number of light source images. 2. The projection type image display device according to claim 1, wherein the two cylindrical lens arrays are formed on a front surface and a back surface of one medium. 3. The two cylindrical lens arrays are formed by closely adhering two low-refractive-index media having concave grooves serving as lens surfaces to a high-refractive-index medium from opposite directions. The projection type image display device according to claim 1, wherein: 4. The apparatus according to claim 1, wherein each of the two cylindrical lens arrays includes a medium having birefringence on one side of a lens surface, and functions as a lens with only a predetermined polarization component. Projection type image display device. 5. The light source image forming optical system includes a lens array in which lens cells substantially similar in shape to the liquid crystal panel are two-dimensionally arranged, and each lens cell forms an image of light from the light source. The projection-type image display device according to claim 1, wherein the plurality of light source images are formed by: 6. The light source image forming optical system is composed of a rod-shaped member having a cross section substantially similar in shape to the liquid crystal panel. The projection-type image display device according to claim 1, wherein the plurality of light source images are formed by reflection.