JP3692653B2 - Projection display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a configuration of a projection display device that enlarges and displays an image formed on a liquid crystal device on a screen.
[0002]
[Prior art]
As an optical system of a projection display device, important problems to be solved include improvement of light use efficiency and uniform illuminance distribution of illumination light. This is because it is possible to realize a brighter display state by improving the light use efficiency and a display state free from uneven brightness by making the illuminance distribution uniform.
[0003]
Here, as a representative example of a technique for improving the uniformity of illumination light, as described in Japanese Patent Laid-Open No. 3-111806, an optical system that divides light from a light source into a plurality of intermediate light beams ( One using an integrator optical system) is known.
[0004]
On the other hand, in an element having a pixel such as a liquid crystal device, an area ratio (aperture ratio) per pixel occupied by a pixel opening through which light passes is reduced as the pixel density is increased. Techniques for improving the rate are known. That is, the illumination light beam is divided by each microlens arranged corresponding to the pixel opening portion, and the divided light fluxes are respectively condensed and passed through the pixel opening portion in a state in which the light beam diameter is narrowed. The light transmittance (that is, light utilization efficiency) is improved. As a result, light utilization efficiency can be improved and a bright image can be obtained.
[0005]
[Problems to be solved by the invention]
However, even if the modulation element in which the microlens is arranged in this way is simply adopted in a projection display apparatus employing the integrator optical system, the light source image formed by the lens plate constituting the integrator optical system and the modulation element Since the pixel arrangement does not match, the projected image becomes non-uniform as a result, and a bright image cannot be obtained.
[0006]
Therefore, the present invention pays attention to the property of light required by the modulation element, and effectively guides the light emitted from the light source to the pixel opening of the modulation element to greatly improve the light utilization efficiency. It is an object of the present invention to propose a projection display device that can obtain a bright and uniform projection image.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, a first projection display device of the present invention provides:
A first secondary light source image forming unit that forms a plurality of first secondary light source images on substantially the same plane from light emitted from the light source, and the first 2 on substantially the same plane. The second secondary light source image forming means for forming a second secondary light source image obtained by doubling the plurality of first secondary light source images formed by the secondary light source image forming means on substantially the same plane. A tertiary light source image forming means for forming a tertiary light source image from the second secondary light source image formed by the second secondary light source image forming means, and a third light source image forming means emitted from the tertiary light source image forming means. Modulation means for modulating light by pixels, and the ratio of the vertical arrangement pitch and the horizontal arrangement pitch of the tertiary light source image is such that the vertical arrangement pitch and the horizontal arrangement pitch of the pixels are The optical characteristics of the first secondary light source image forming means or the tertiary light source image forming means are substantially the same as the ratio of Characterized in that it is a constant.
[0008]
According to said structure, since the two secondary light source image formation means are used, it becomes possible to reduce the brightness nonuniformity of a projection image significantly. In addition, the first light source image has a ratio between the vertical arrangement pitch and the horizontal arrangement pitch of the tertiary light source image (hereinafter simply referred to as “arrangement pitch ratio”) substantially equal to the pixel arrangement pitch ratio. Since the optical characteristics of the secondary light source image forming means or the tertiary light source image forming means are determined, it is possible to effectively guide the light emitted from the light source to the pixel opening of the modulation element, and an extremely bright projected image Can be obtained.
[0009]
In the first projection display device, the ratio of the arrangement pitch of the second secondary light source images is substantially the same as the ratio of the arrangement pitch of the pixels, or the vertical pitch of the first secondary light source image. The optical characteristics of the first secondary light source image forming means so that the ratio between the half of the arrangement pitch and the horizontal arrangement pitch is substantially the same as the ratio of the pitch of the pixels of the modulation means. Is determined, any tertiary light source image forming means can be used only by changing the optical characteristics of the first secondary light source image forming means.
[0010]
That is, the tertiary light source image forming means is generally formed of a microlens, but if the optical characteristics of the first secondary light source image forming means are changed, there is no general toric curved surface. A microlens having a typical spherical shape can be used, and the microlens can be easily manufactured.
[0011]
In the first projection display device, the first secondary light source image forming unit includes a plurality of rectangular light beam splitting lenses arranged on substantially the same plane, and the aspect ratio of the light beam splitting lens is What is substantially the same as the aspect ratio of the illuminated area of the modulating means can be employed. In this way, when the aspect ratio of the light beam splitting lens is set in accordance with the aspect ratio of the illuminated area set slightly larger than the effective image forming area of the modulation means, each image formed by the light beam splitting lens is respectively It can be superimposed on the illuminated area with approximately the same size as the illuminated area. Therefore, it is possible to obtain a projection image with a more uniform illumination distribution in the illuminated area of the modulation means and less brightness unevenness.
[0012]
Furthermore, in the first projection display device, a color separation unit that separates light emitted from the light source into two or more color lights, and a plurality of the modulations that respectively modulate the color lights separated by the color light separation unit And color reproducibility by providing a color light combining means for combining the color lights modulated by the respective modulation means and a projection optical system for projecting the color light combined by the combining means. A small projection display device capable of displaying a color image with high resolution can be realized.
[0013]
Next, a second projection display apparatus of the present invention includes a light source, a light beam splitting unit that splits an incident light beam from the light source into a plurality of intermediate light beams, and forms a plurality of light source images, and a plurality of the intermediate light beams. A polarization generating means comprising: a polarization separating means for separating each of the light beams into polarized light beams having two types of polarization directions; and a polarization conversion means for aligning the polarization directions of the two types of polarized light beams separated by the polarization separation means; A modulation unit having a microlens disposed on the polarization generation unit side, the modulation unit including a plurality of pixels, and a vertical arrangement pitch and a horizontal arrangement pitch of a light source image formed by the microlens, The optical characteristics of the light beam splitting means or the microlens are determined so that the ratio of the luminous flux becomes substantially the same as the ratio of the vertical arrangement pitch and the horizontal arrangement pitch of the pixels. .
[0014]
According to the above configuration, the projection display apparatus of the present invention divides a random polarized light beam emitted from the light source into a plurality of light beams, and each of the light beams is converted into a polarized light beam having almost one kind of polarization direction. After the conversion, the modulation means is illuminated by superimposing on the modulation means, so that the modulation means can be illuminated uniformly with a light beam having a uniform polarization direction, and the polarized light beam incident on the modulation means The microlens attached to the light is condensed again while being divided into a plurality of light beams, and is guided onto the pixels of the modulation means, so that the light utilization efficiency in the modulation means can be extremely increased. In addition, there is almost no light loss in the generation process of the polarized light flux. Therefore, the light use efficiency in the projection display device can be made extremely high, and a projection display device that can display a bright projection image without uneven brightness can be realized. Therefore, even when trying to realize a projection display device capable of displaying a very bright projected image using a light source lamp having a very large light output, the cooling device for preventing the temperature rise of the modulation means is small. Therefore, it is possible to realize a small projection display device that is quiet and quiet.
[0015]
Here, a transmissive or reflective liquid crystal device or the like can be used as the modulation means.
[0016]
In addition, the light source section is generally composed of a light source lamp and a reflector, and as a light source lamp, a metal halide lamp, a xenon lamp, a halogen lamp, etc., and as a reflector, a parabolic reflector, an elliptical reflector, A spherical reflector or the like can be used.
[0017]
The above configuration employs a mechanism that transmits a light source image (secondary light source image) formed by the polarization generating means as a new light source image (tertiary light source image) onto the pixels of the modulation means by the microlens. It is not always necessary to form the microlens so that the microlens formed on the microlens array plate has a one-to-one correspondence with the pixels of the modulation means. That is, the number of microlenses on the microlens array plate need not necessarily match the number of pixels of the modulation means, and the number of microlenses may be an integral number of the number of pixels of the modulation means. In this case, a plurality of secondary light source images are transmitted onto a plurality of pixels by one microlens.
[0018]
The microlens can be easily obtained by cutting, press molding, and optical molding the surface of a glass material, a transparent crystallized glass material, and a resin material.
[0019]
In addition, the microlens may be manufactured once on another substrate (microlens array plate) and attached to the modulation means as a microlens array plate, but it is integrated with a part of the substrate constituting the modulation means from the beginning. In this case, the modulation means can be reduced in thickness and cost.
[0020]
In the second projection display device, a plurality of light source images formed by the polarization generating means are arranged so that the ratio of the arrangement pitch of the light source images and the ratio of the arrangement pitch of the pixels are substantially the same. Adopting the optical characteristics of the beam splitting lens so that the ratio of the half of the vertical array pitch of the light source image and the horizontal array pitch is substantially the same as the ratio of the pixel array pitch can do.
[0021]
The optical characteristics of the light beam splitting means are, for example, that the light beam splitting means is composed of a lens plate partially or entirely composed of decentered lenses, or a first lens plate consisting of a plurality of concentric lenses and a plurality of cylindrical lenses. It can be easily changed by combining with the second lens plate. By using such a lens, the formation position of the condensed image (secondary light source image) can be freely controlled, so that the arrangement of the condensed image can easily correspond to the arrangement of the pixels of the modulation means. Because it can.
[0022]
Thereby, a microlens having a general spherical shape without a toric curved surface can be used, and the production of the microlens is facilitated.
[0023]
In the second projection display device, the first secondary light source image forming unit includes a plurality of rectangular light beam splitting lenses arranged on substantially the same plane, and the aspect ratio of the light beam splitting lens of the scene is What is substantially the same as the aspect ratio of the illuminated area of the modulating means can be employed. In this way, when the aspect ratio of the light beam splitting lens is set in accordance with the aspect ratio of the illuminated area set slightly larger than the effective image forming area of the modulation means, each image formed by the light beam splitting lens is respectively It can be superimposed on the illuminated area with approximately the same size as the illuminated area. Therefore, it is possible to obtain a projection image with a more uniform illumination distribution in the illuminated area of the modulation means and less brightness unevenness.
[0024]
On the other hand, in the second projection display device, when the optical characteristics of the light beam splitting lens are not changed, a part or all of the microlens may be a toric lens. In the toric lens, the X-axis direction and the Y-axis direction have different lens curvatures. Therefore, when transmitting the secondary light source image, the intervals of the secondary light source image arrangement are respectively in the X-axis direction and the Y-axis direction. Can be changed independently. Therefore, even when the arrangement of the secondary light source images and the arrangement of the pixels of the modulation means are not similar, the secondary light source image can be transmitted onto the pixels of the modulation means. This has the effect of improving the degree of freedom. Also, with this configuration, the first optical element that is the light beam splitting means and the condensing lens array can be shared by the same lens array body, so that the cost of the optical system can be reduced.
[0025]
In the second projection display device, the polarization separation means is formed in parallel with the polarization separation surface that separates each of the plurality of intermediate light beams into polarized light beams having two types of polarization directions, and the polarization separation surface In addition, a plurality of polarization separation units having a reflection surface for emitting one of the two types of polarized light beams separated by the polarization separation surface in substantially the same direction as the emission direction of the other polarized light beam can be provided. .
[0026]
By employing such a polarization separation means, it becomes possible to perform polarization separation in a small space, and the projection display device can be miniaturized.
[0027]
Note that in such a configuration using the polarization separation means, a parallelizing lens for collimating the light beam emitted from the polarization generation device may be disposed between the polarization generation device and the modulation means. it can. In that case, the condensing performance of the microlens can be improved, and therefore the size of the formed tertiary light source image can be reduced, and the tertiary light source image can be more easily formed on the pixel of the polarizing means. Therefore, there is an effect that the light utilization efficiency in the modulation means can be further improved.
[0028]
Further, in order to condense and guide the intermediate light beams emitted from the light beam dividing means to the polarization separating means, the same number of light collecting lenses as the light beam dividing lenses constituting the light beam dividing means are arranged in a two-dimensional manner. The condensing lens array can be arranged between the beam splitting means and the polarization separating means. In this case, each intermediate light beam can be efficiently guided to a specific place on each polarization separation unit, and there is an effect that the light utilization efficiency in the polarization generating means can be further improved. Note that the condensing lens array can be integrated with the polarization separating means, and in this case, there is an effect that light loss at the interface can be reduced.
[0029]
Further, a coupling lens for superimposing and coupling a polarized light beam having the same polarization direction emitted from the polarization generation unit on the modulation unit can be arranged between the polarization generation unit and the modulation unit. In that case, there is an effect of facilitating the superposition coupling on the modulation means of the polarized light beam having the same polarization direction. Further, there is also a secondary effect that the size of the illumination area on the modulation means can be easily changed by changing the lens characteristics (magnification) of the coupling lens.
[0030]
Furthermore, a light-shielding plate for allowing each of the intermediate light beams emitted from the light beam splitting means to enter only the portion of the polarization splitting surface of each polarization splitting unit is disposed between the beam splitting means and the polarization splitting unit. It can be configured. In that case, the intermediate light beam directly incident on the reflection surface of the polarization separation unit can be eliminated and the intermediate light beam can be guided only to the polarization separation surface. It is possible to prevent a polarized light beam having Therefore, when a liquid crystal device is used as the modulation means, the amount of light absorption by the polarizing plate provided in the liquid crystal device can be reduced, and the temperature rise of the liquid crystal device and the polarizing plate can be prevented. Furthermore, it is possible to use a light source that emits outgoing light with poor parallelism by installing a light shielding plate. The light shielding plate can also be integrated with the condenser lens array or the polarization separating means, and in this case, there is an effect that the optical system can be miniaturized.
[0031]
In the second projection display device, a microlens composed of a gradient index microlens may be employed. In that case, since the surface of the microlens array plate can be flattened, the microlens array plate and the modulation means can be easily integrated, and light loss at the interface between the microlens array plate and the modulation means can be reduced. There is an effect that can be reduced.
[0032]
Alternatively, a close-packed microlens may be employed. In this case, since the lenses can be arranged without a gap, there is an effect that the light utilization efficiency in the microlens array plate can be further improved.
[0033]
The microlens array plate may be integrated with the modulation means. In that case, since the optical loss at the interface between the microlens array plate and the modulation means can be reduced, the light utilization efficiency in the modulation means can be further improved. In particular, if the microlens array plate and the substrate constituting the modulation means are the same substrate, the modulation means can be made thinner.
[0034]
Further, in the second projection display device, color light separating means for separating light emitted from the light source into two or more color lights, and a plurality of the modulation means for modulating each color light separated by the color light separating means, respectively. And color light synthesizing means for synthesizing the respective color lights modulated by the respective modulation means and a projection optical system for projecting the respective color lights synthesized by the color synthesizing means. It is possible to realize a small projection display device that can display a color image with high resolution.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, for convenience, three directions orthogonal to each other are defined as an X-axis direction (lateral direction), a Y-axis direction (vertical direction), and a Z-axis direction (system optical axis direction). Moreover, in each Example, the part which has the same function is attached | subjected the same code | symbol, and duplication of description is avoided.
[0036]
(Example 1)
FIG. 1 is a schematic configuration diagram showing the optical main part of a projection display device to which the present invention is applied in a plan view. The projection display device 1 of this example includes a light source unit 10 and a secondary light source image forming unit 20 arranged along the system optical axis L (Z-axis direction), a liquid crystal device unit 40 as a modulation unit, and a projection optical system. The projection lens 50 is generally configured. The randomly polarized light beam emitted from the light source unit 10 is converted into one type of polarized light beam whose polarization directions are substantially uniform by the secondary light source image forming unit 20, illuminates the liquid crystal device unit 40, and is projected through the projection lens 50. It reaches the screen 60 which is a surface. Note that a transmissive liquid crystal device is used in the liquid crystal device portion of this example.
[0037]
The light source unit 10 is generally composed of a light source lamp 101 and a parabolic reflector 102, and light emitted from the light source lamp is reflected in one direction by the parabolic reflector 102 to become a substantially parallel light beam. The light enters the secondary light source image forming means 20. Here, the light source optical axis R of the light source unit 10 is parallel-shifted in the X direction by a certain distance D (corresponding to 1/4 of the lateral width of the light beam splitting lens) with respect to the system optical axis L. The light source unit 10 is arranged.
[0038]
Next, the secondary light source image forming unit 20 includes a first optical element 200 as a beam splitting unit and a second optical element 300 that mainly functions as a polarization generating unit.
[0039]
As shown in FIG. 2, the first optical element 200 is configured by arranging a plurality of light beam splitting lenses 201 having a rectangular outer shape (opening shape) on an XY plane in an orthogonal matrix. . The positional relationship between the light source unit 10 and the first optical element 200 is set so that the light source optical axis R is at the center of the first optical element 200. The light incident on the first optical element 200 is split into a plurality of intermediate light beams 202 by the light beam splitting lens 201, and at the same time in a plane perpendicular to the system optical axis L (XY in FIG. The same number of condensing images (secondary light source images) 203 as the number of light beam splitting lenses are formed at the position where the intermediate light beam on the plane is converged. Since this condensed image is nothing but the light source image formed through the beam splitting lens, it will be referred to as a secondary light source image below.
[0040]
The outer shape of the light beam splitting lens 201 on the XY plane is set to be similar to the shape of the illuminated region of the liquid crystal device 401 constituting the liquid crystal device unit 40. In this example, it is assumed that the liquid crystal device has a horizontally long effective image forming region (vertical: horizontal aspect ratio is 3: 4) long in the X direction on the XY plane. The illuminated area is an area on which the light source image is to be projected on the liquid crystal device 401, and is usually set slightly larger than the effective image forming area in order to provide a margin for the effective image forming area of the liquid crystal device. ing. If the aspect ratio of the light beam splitting lens is set in accordance with the aspect ratio of the illuminated area, the individual images formed by the luminous flux dividing lens can be superimposed on the illuminated area in approximately the same size as the illuminated area. it can. Therefore, it is possible to obtain a projection image with a more uniform illumination distribution in the illuminated area of the modulation means and less brightness unevenness. In this example, the vertical: horizontal aspect ratio of the illuminated area is set to 3: 4. Therefore, the vertical: horizontal aspect ratio of the light beam splitting lens 201 is also set to approximately 3: 4. Therefore, the ratio of the arrangement pitch in the X-axis direction and the arrangement pitch in the Y-axis direction of the light beam splitting lens is 1: 3/4.
[0041]
Further, the arrangement of the beam splitting lenses is not limited to the orthogonal matrix as shown in FIG. For example, a so-called delta arrangement in which the rows of the light beam splitting lenses constituting the even rows are shifted in the X-axis direction from the rows of the light flux splitting lenses constituting the odd rows may be employed.
[0042]
An eccentric lens is used as a part of the light beam splitting lens 201 constituting the first optical element, and the formation position of the secondary light source image formed by the light beam splitting lens is adjusted. FIG. 3 is a diagram showing the position of the lens optical axis in each light beam splitting lens. In FIG. 3, only the light beam splitting lens constituting the third row is a general concentric lens (the lens optical axis is set at the center of the lens). The other light beam splitting lenses constituting the first, second, fourth, and fifth rows are all decentered lenses in which the lens optical axis 210 is shifted in the Y-axis direction. However, the lens characteristics of a series of light beam splitting lenses constituting the same row are all the same. As a result, a series of secondary light source images are formed in an orthogonal matrix as shown in FIG. 4 (when the secondary light source image forming means 20 is viewed from the light source unit 10 side). However, the ratio of the arrangement pitch in the X-axis direction and the arrangement pitch in the Y-axis direction of the secondary light source image is 1: 1/2, and the ratio between the X-axis direction and the Y-axis direction of the light beam splitting lens in the first optical element is This is different from the arrangement pitch ratio (1: 3/4). This is because an eccentric lens whose lens optical axis is shifted in the Y-axis direction is used as a part of the light beam splitting lens constituting the first optical element. As a result, the secondary light source image in the Y-axis direction is used. This is because only the arrangement pitch is narrowed. Note that depending on the number of light beam splitting lenses constituting the first optical element or the arrangement thereof, all the light beam splitting lenses may be decentered lenses. Further, instead of the first optical element 200 of the present example, a secondary light source may be configured using a first optical element configured using only a concentric lens and a cylindrical lens that collects light only in one direction. It is possible to adjust only the arrangement pitch in the Y-axis direction of the image.
[0043]
The second optical element 300 is a composite that is substantially composed of a condensing lens array 310, a light shielding plate 370, a polarization separation unit array 320, a selective phase difference plate 380, and a coupling lens 390, and is based on the first optical element 200. It is arranged in a plane perpendicular to the system optical axis L (XY plane in FIG. 1) near the position where the secondary light source image 203 is formed. The second optical element 300 spatially separates each of the intermediate light beams 202 into a P-polarized light beam and an S-polarized light beam, and then aligns the polarization direction of one polarized light beam with the polarization direction of the other polarized light beam, It has a function of guiding each polarized light beam having substantially the same polarization direction to the effective image forming area of the liquid crystal device 401.
[0044]
The condensing lens array 310 has substantially the same configuration as that of the first optical element 200, that is, the same number of condensing lenses 311 as the light beam splitting lenses 201 constituting the first optical element 200 are arranged in a matrix. It has a function of guiding each intermediate light beam 202 while condensing it to a specific location of the polarization separation unit array 320. Therefore, it is ideal that the light incident on the polarization separation unit array is parallel to the system optical axis L in accordance with the characteristics of the intermediate light beam formed by the first optical element. Considering this point, the lens characteristics of each condenser lens are optimized. Therefore, the condensing lens array of this example is configured using an eccentric lens as a part thereof. Here, the condensing lens array may be disposed at a position (side closer to the first optical element) away from the light shielding plate 370 and the polarization separation unit array. Further, the condensing lens array may be omitted depending on the configuration of the secondary light source image forming unit 20 itself and the characteristics of the light emitted from the light source unit 10. In particular, when the parallelism of the light beam incident on the first optical element is extremely good, the condensing lens array may be omitted from the second optical element.
[0045]
As shown in FIG. 5, the light shielding plate 370 is configured such that a plurality of light shielding surfaces 371 and a plurality of opening surfaces 372 indicated by diagonal lines in the drawing are regularly arranged. The incident light beam is blocked, and the light beam incident on the opening surface 372 passes through the light shielding plate 370 as it is. That is, the light shielding plate 370 has a function of controlling the light beam that is transmitted according to the position on the light shielding plate. The positions of the light shielding surface 371 and the opening surface 372 are set so that the position where the secondary light source image 203 is formed is limited to the polarization separation surface 331 of the polarization separation unit 330 described later. In this example, as the light shielding plate 370, a plate-shaped transparent body made of a glass plate or the like is used in which a light shielding film made of a chromium film, an aluminum film or the like is partially formed. You may use what provided the opening part in such a light-shielding flat plate. Further, when the light shielding surface 371 is formed using a light shielding film as in this example, the light shielding film may be directly formed on the condenser lens array 310 or a polarization separation unit array 320 described later. A similar function can be exhibited. In this case, there is an advantage that the number of parts does not increase. If a light source that emits a light beam with good parallelism is used, the light shielding plate can be omitted.
[0046]
Next, the polarization separation unit array 320 has a configuration in which a plurality of polarization separation units 330 are arranged in a matrix as shown in FIG. The arrangement method of the polarization separation units corresponds to the lens characteristics of the light beam splitting lens 201 constituting the first optical element 200 and the arrangement method thereof. That is, in this example, the beam splitting lenses are arranged in an orthogonal matrix, and the first optical element is configured by using an eccentric lens as a part of the beam splitting lens, and in particular, the Y-axis direction of the secondary light source image In order to reduce the arrangement pitch, the polarization separation unit array having a size corresponding to the arrangement pitch of the secondary light source image is arranged in an orthogonal matrix in the same direction. It is composed. Therefore, the vertical / horizontal aspect ratio of the polarization separation unit on the XY plane is 1: 2.
[0047]
When all of the polarization separation units in the same column lined up in the Y-axis direction are the same polarization separation unit, a polarization separation unit array configured by arranging elongated polarization separation units in the Y-axis direction in the X-axis direction is used. Therefore, it is advantageous in that the optical loss at the interface between the polarization separation units can be reduced and the manufacturing cost of the polarization separation unit array can be reduced. Furthermore, it is possible to eliminate the interface between the polarization separation units arranged in the X-axis direction. In this case, the optical loss at the interface between the polarization separation units can be reduced and the manufacturing cost of the polarization separation unit array can be reduced. be able to.
[0048]
As shown in FIG. 7, the polarization separation unit 330 is a quadrangular prism-like structure having a polarization separation surface 331 and a reflection surface 332 inside, and each of the intermediate light beams incident on the polarization separation unit is converted into a P-polarized light beam. And S-polarized light flux. Since the vertical / horizontal aspect ratio of the polarization separation unit on the XY plane is 1: 2, the polarization separation surface 331 and the reflection surface 332 are arranged in the horizontal direction (X-axis direction). . Here, the polarization separation surface 331 and the reflection surface 332 are configured such that the polarization separation surface is inclined at about 45 degrees with respect to the system optical axis L, and the reflection surface is parallel to the polarization separation surface. The cross-sectional area projected onto the XY plane by the polarization splitting surface (equal to the area of a P exit surface 333 described later) and the cross-sectional area projected from the reflection surface onto the XY plane (equal to the area of an S exit surface 334 described later). They are arranged to be equal. Therefore, in this example, the width Wp on the XY plane of the region where the polarization separation surface 331 exists and the width Wm on the XY plane of the region where the reflection surface 332 exist are equal to each other, and each of them is the polarization separation unit. It is set to be half of the lateral width W on the XY plane. In general, the polarization separation surface can be formed of a dielectric multilayer film, and the reflection surface can be formed of a dielectric multilayer film or an aluminum film.
[0049]
The light incident on the polarization separation unit 330 travels in the direction of the P-polarized light beam 335 passing through the polarization separation surface without changing the traveling direction on the polarization separation surface 331 and the direction of the adjacent reflection surface 332 reflected by the polarization separation surface. Are separated into an S-polarized light beam 336 for changing. The P-polarized light beam 335 is emitted from the polarization separation unit as it is through the P emission surface 333, and the S-polarized light beam 336 changes its traveling direction again at the reflection surface 332 and becomes substantially parallel to the P-polarized light beam 335, so that the S emission surface. The light is emitted from the polarization separation unit via 334. Therefore, the random polarized light beam incident on the polarization separation unit is separated into two types of polarized light beams of P-polarized light beam and S-polarized light beam having different polarization directions by the polarization separation unit. The light is emitted in substantially the same direction from the emission surface.
[0050]
As described above, since the number of light beams increases by a factor of two when the light beam passes through the polarization separation unit, the number of secondary light source images formed in the polarization separation unit is also the emission surface of the polarization separation unit. From the side of, it seems to increase twice as well. That is, as shown in FIG. 8, in the polarization separation unit array, in one polarization separation unit, a secondary light source image 204 (right side) with a P-polarized light beam and a secondary light source image 205 (toward) with an S-polarized light beam. The two secondary light source images (on the left side) are formed in a state of being arranged in pairs in the horizontal direction (X-axis direction). Compared with the case where the secondary light source image is formed as shown in FIG. 4, the secondary light source image array pitch in the X axis direction is substantially increased due to the increase of the secondary light source images in the X axis direction. It can be seen that the ratio of the arrangement pitch in the X-axis direction and the arrangement pitch in the Y-axis direction of the secondary light source image is 1: 1. That is, the arrangement pitch of the secondary light source images arranged in the X-axis direction and the arrangement pitch of the secondary light source images arranged in the Y-axis direction are both equal to U / 2, and all the secondary light source images are arranged in an orthogonal matrix. Has been. What is important here is that the arrangement of the secondary light source images completely corresponds to the arrangement of the pixel openings of the liquid crystal device described later.
[0051]
Since the polarization separation unit has the functions as described above, it is necessary to guide the intermediate light beam to a region where the polarization separation surface of the polarization separation unit exists. Therefore, the intermediate light beam is provided at the center of the polarization separation surface in the polarization separation unit. The position relationship between each polarization separation unit and each condenser lens and the lens characteristics of the condenser lens are set so that a secondary light source image is formed. In particular, in the case of this example, since the central axis of each condenser lens is arranged at the center of the polarization separation surface in each polarization separation unit, the condenser lens array 310 includes the polarization separation unit. They are arranged in a state shifted in the X direction with respect to the polarization separation unit array 320 by a distance corresponding to ¼ of the lateral width W.
[0052]
Again, a description will be given based on FIG.
[0053]
The light shielding plate 370 is located between the polarization separation unit array 320 and the condensing lens array 310 so that the center of each opening surface 372 of the light shielding plate 370 and the center of the polarization separation surface 331 of each polarization separation unit 330 substantially coincide with each other. Further, the opening width of the opening surface 372 (the opening width in the X direction) is set to about half the width W of the polarization separation unit 330. As a result, the intermediate light beam directly incident on the reflection surface without passing through the polarization separation surface is hardly present because it is blocked by the light shielding surface of the light shielding plate in advance, and almost all of the light flux that has passed through the opening surface of the light shielding plate. It is incident only on the polarization separation surface. Therefore, by installing the light shielding plate, in the polarization separation unit, there is almost no light beam that directly enters the reflection surface and enters the adjacent polarization separation surface through the reflection surface. In general, the size of the formed secondary light source image varies depending on the degree of parallelism of the light beam emitted from the light source. For this reason, when a light source that emits a light beam with good parallelism is used, the formed secondary light source image becomes small, so that there is almost no light beam directly incident on the reflection surface of the polarization separation unit, but a light beam with poor parallelism. When a light source that emits light is used, the secondary light source image becomes large, so that there are many light beams that are directly incident on the reflection surface of the polarization separation unit, and these light beams are polarizing plates (see FIG. (Not shown) and the temperature of the polarizing plate is increased. Therefore, when a light source that emits a light beam with poor parallelism is used, an increase in the temperature of the polarizing plate can be prevented by installing a light shielding plate.
[0054]
A selective phase difference plate 380 in which λ / 2 phase difference plates 381 are regularly arranged is installed on the exit surface side of the polarization separation unit array 320. That is, the λ / 2 phase difference plate 381 is disposed only on the P exit surface 333 of the polarization separation unit 330 constituting the polarization separation unit array 320, and the λ / 2 phase difference plate 381 is disposed on the S exit surface 334 portion. Not installed (see Figure 7). Due to such an arrangement state of the λ / 2 phase difference plate, the P-polarized light beam emitted from the polarization separation unit is converted into an S-polarized light beam by rotating the polarization direction when passing through the λ / 2 phase difference plate. Is done. On the other hand, since the S-polarized light beam emitted from the S exit surface does not pass through the λ / 2 phase difference plate, the polarization direction does not change and passes through the selected phase difference plate as it is. In summary, the intermediate beam having a random polarization direction is converted into one type of polarized beam (in this case, an S-polarized beam) by the polarization separation unit array 320 and the selective phase difference plate 380.
[0055]
A coupling lens 390 is disposed on the exit surface side of the selective phase difference plate 380, and the light beam aligned with the S-polarized light flux by the selective phase difference plate is transferred to the effective image forming area of the liquid crystal device 401 by the coupling lens. And is superimposed and coupled on the effective image forming area. Here, the coupling lens 390 does not have to be a single lens body, and may be an aggregate of a plurality of lenses like the first optical element 200. Further, the coupling lens may be omitted depending on the lens characteristics of the condenser lens 311 and the light beam splitting lens 201 described above, the arrangement state thereof, or the installation angle of the polarization separation surface and the reflection surface of the polarization separation unit 330. .
[0056]
Summarizing the functions of the second optical element 300, the intermediate light beam 202 divided by the first optical element 200 (that is, the aperture plane cut out by the light beam dividing lens 201) is converted into a liquid crystal device by the second optical element 300. 401 are superimposed on the effective image forming area 401. At the same time, the intermediate light beam, which is a random polarized light beam, is spatially separated into two types of polarized light beams having different polarization directions by the polarization separation unit array 320 on the way, and is almost one when passing through the selective phase difference plate 380. It is converted into a kind of polarized light beam. Here, since the light shielding plate 370 is disposed on the incident side of the polarization separation unit array 320 and the intermediate light beam is incident only on the polarization separation surface 331 of the polarization separation unit 330, the polarization separation is performed via the reflection surface 332. There is almost no intermediate light beam incident on the surface 331, and the type of polarized light beam emitted from the polarization separation unit array 320 is limited to almost one type. Therefore, the effective image forming area of the liquid crystal device 401 is illuminated almost uniformly with almost one type of polarized light beam.
[0057]
The liquid crystal device unit 40 includes a liquid crystal device 401, a collimating lens 405 disposed on the incident side (light source side) of the liquid crystal device, an exit side condensing lens 406 disposed on the exit side (projection lens side) of the liquid crystal device, and a liquid crystal. The microlens array plate 402 is arranged roughly on the incident side (light source side) of the device 401.
[0058]
FIG. 9 shows a cross-sectional structure of the liquid crystal device 401 and the microlens array plate 402. The liquid crystal device 401 has a structure in which a liquid crystal layer 472 is sandwiched between a liquid crystal substrate 471 on which an electrode (not shown) is formed and a counter substrate 475 on which a light shielding layer 473 and an electrode (not shown) are formed. The microlens array plate 402 has a configuration in which microlenses 403 are formed on a microlens substrate 476 so as to correspond to the pixel openings 474 on a one-to-one basis. Here, the arrangement of the pixels in the liquid crystal device 401 is an orthogonal matrix, the arrangement pitch of the pixels in the X-axis direction is equal to the arrangement pitch in the Y direction, and the shape of the pixel openings 474 is also substantially square. Therefore, the pixel openings 474 and the microlenses 403 are arranged in an orthogonal matrix with the same arrangement pitch in the X-axis direction and the Y-axis direction. Here, the secondary light source images formed in the polarization separation unit array are arranged in an orthogonal matrix, and considering that the arrangement pitch in the X-axis direction is equal to the arrangement pitch in the Y-axis direction, It can be seen that the arrangement state of the two types of secondary light source images 204 and 205 formed by the polarization separation unit array 320 and the pixel openings 474 of the liquid crystal device 401 are completely similar. Note that the microlens 403 may be formed directly on the counter substrate 475 and the microlens substrate 476 may be omitted. Further, the microlens is of a type (refractive index distribution type) that obtains a light collecting power by forming a refractive index distribution in addition to a type that obtains a light collecting power by a curved surface shape as shown in FIG. In particular, in the latter case, the surface of the microlens array plate can be made flat, so that the microlens array plate and the counter substrate can be optically integrated to reduce light loss at the interface. It is effective in.
[0059]
The illuminating light beam incident on the liquid crystal device unit 40 configured as described above can be suppressed in the divergence angle by the collimating lens 405 (when focusing on the light beam formed by one light beam splitting lens, the collimating lens makes it substantially parallel. The light enters a microlens array plate 402 installed in the liquid crystal device 401 and is condensed by each microlens 403 to form a condensed image 470 in the pixel opening 474. Since this condensed image 470 is nothing but a projection image of the secondary light source image, it will be referred to as a tertiary light source image below. The microlenses are formed so as to correspond to the pixel openings in a one-to-one correspondence. In this example, as shown in FIG. 9, a plurality of tertiary light source images 470 are formed by a single microlens. Are formed in the pixel opening 474. In other words, the tertiary light source image 470 formed in one pixel opening is a light source image formed by a plurality of microlenses 403. This means that even if a plurality of microlenses 403 are integrated, it is possible to form a tertiary light source image in the pixel opening 474 in the same manner. Therefore, the microlens 403 is formed in the pixel opening 474. However, it is not necessary to form a one-to-one correspondence. That is, the number of microlenses 403 is not necessarily the same as the number of pixels of the liquid crystal device, and may be 1 / integer of the number of pixels. By using the microlens array plate 402 on which the microlens 403 having an integer number of pixels is formed, even if the secondary light source images are arranged in a delta shape, the arrangement of the microlenses 403 is not changed. Can respond.
[0060]
When the functions of the microlens array plate 402 are summarized, the two types of secondary light source images 204 and 205 formed by the polarization separation unit array 320 are converted into the liquid crystal device 401 by the respective microlenses 403 formed on the microlens substrate 476. That is, a third light source image 470 is formed on the pixel opening 474. As described above, since the arrangement of the secondary light source images formed in the polarization separation unit array 320 is the same as the arrangement of the pixel openings 474 of the liquid crystal device 401, all the secondary light sources are arranged. The images 204 and 205 become a tertiary light source image 470 and pass through the pixel opening 474. Accordingly, since most of the illumination light beam incident on the liquid crystal device 401 can pass through the liquid crystal device 401 without being blocked by the light shielding layer 473, the light utilization efficiency in the liquid crystal device 401 is very high.
[0061]
Again, a description will be given based on FIG. In the liquid crystal device unit 40, display information from the outside is included in the light beam passing through the liquid crystal device 401 to form an optical image. The optical image formed here is projected and displayed on the screen 60 through the projection lens 50. The exit side condensing lens 430 disposed on the projection lens side of the liquid crystal device 401 is disposed to effectively guide the light beam that has passed through the liquid crystal device 401 to the projection lens, and may be omitted depending on the characteristics of the projection lens. can do. However, since the light beam emitted from the liquid crystal device 401 is a divergent light beam due to the light condensing action of the microlens 403 described above, an output side condensing lens 406 is disposed adjacent to the liquid crystal device 401, Condensing the divergent light beam and guiding it to the projection lens 50 is effective in that the light use efficiency in the projection lens 50 can be improved.
[0062]
In the projection display device 1 configured as described above, a liquid crystal device of a type that modulates one type of polarized light beam is used. Therefore, when a random polarized light beam is guided to a liquid crystal device using a conventional illumination device, about half of the random polarized light beam is absorbed by a polarizing plate (not shown) and converted to heat. However, there is a problem that a large-sized and noisy cooling device that suppresses the heat generation of the polarizing plate is necessary in addition to the low light utilization efficiency. Also in the liquid crystal device, since the area ratio per pixel occupied by the light shielding layer increases as the pixel density increases, the degree to which the illumination light beam is blocked in the light shielding layer is increased, so that the light use efficiency is poor and the liquid crystal device is also used. There is a problem that a large-sized and noisy cooling device that suppresses heat generation is necessary. However, in the projection display apparatus 1 of this example, this problem is greatly improved.
[0063]
That is, according to the projection display apparatus 1 of the present example, the secondary light source image forming unit configured by the first optical element 200 and the second optical element 300 is used to generate a random polarized light beam emitted from the light source unit 10. 20, the light beam is converted into almost one type of polarized light beam, and the effective image forming area of the liquid crystal device 401 can be uniformly illuminated by the light beam having the same polarization direction, so that a projected image having no brightness unevenness can be obtained. In addition, since almost no light loss is involved in the generation process of the polarized light flux, almost all of the light emitted from the light source unit can be guided to the effective image forming area of the liquid crystal device 401, and further installed in the liquid crystal device 401. Since the microlens array plate 402 that has been used can pass most of the light incident on the liquid crystal device 401 through the pixel opening without being blocked by the light shielding layer of the liquid crystal device, the light utilization efficiency is extremely high. The effect is that a bright projected image can be obtained.
[0064]
Further, when a projection display device is configured using a modulation unit that performs display using a polarized light beam like a liquid crystal device, the amount of light absorbed by the polarizing plate installed in the liquid crystal device 401 can be greatly reduced. Therefore, the cooling device required for suppressing the heat generation of the polarizing plate and the modulation means can be greatly reduced in size. In particular, since the light shielding plate 370 is disposed inside the second optical element 300, other polarized light beams unnecessary for display on the liquid crystal device may be mixed in the illumination light that illuminates the liquid crystal device. rare. Therefore, the amount of light absorption in the polarizing plate arranged on the light incident side of the liquid crystal device is extremely small, and the amount of heat generated by light absorption is also extremely small. The cooling device can be further downsized.
[0065]
From the above, even when trying to realize a projection display device capable of displaying a very bright projection image using a light source lamp with a very large light output, it can be handled by a small cooling device. The noise of the cooling device can be reduced, and a quiet and high-performance projection display device can be realized.
[0066]
Further, in accordance with the shape of the effective image forming area of the horizontally long liquid crystal device 401, the second optical element 300 spatially separates two kinds of polarized light beams in the horizontal direction (X-axis direction). It is in form. Therefore, the amount of light is not wasted, and it is convenient for illuminating a horizontally long liquid crystal device.
[0067]
In general, when a light beam with a random polarization direction is simply separated into a P-polarized light beam and an S-polarized light beam, the width of the entire light beam after separation is doubled, and the optical system is accordingly enlarged. However, in the projection display device of the present invention, a plurality of minute condensed images are formed by the first optical element, and a space where no light is generated in the formation process is used well, and polarization separation is performed in the space. By arranging the reflecting surface of the unit, it absorbs the lateral width expansion of the light beam caused by the separation into two polarized light beams, so that the width of the entire light beam does not widen, and a compact optical The system is realized. This means that when the liquid crystal device is illuminated, there is almost no light incident on the liquid crystal device with a large angle. Therefore, a bright projection image can be realized without using a projection lens system having a very small aperture with a small F number, and as a result, a small projection display device can be realized.
[0068]
In addition, as the two types of polarized light beams are separated in the lateral direction (X-axis direction) in the second optical element 300, one secondary formed by each light beam splitting lens 201 of the first optical element 200. Two secondary light source images 203 and 205 arranged in the horizontal direction from the light source image 203 can be formed. That is, since the secondary light source image 203 is doubled by the second optical element 300, in the projection display apparatus 1 of this example, only the arrangement pitch in the Y-axis direction is set to 2/3 by the second optical element 300. It is not necessary to reduce the arrangement pitch of the secondary light source images in the X-axis direction to ½. Therefore, it is not necessary to increase the degree of decentration of the lens so much, so that the incidence efficiency of the lens does not decrease and the brightness does not decrease, and the spherical aberration does not increase and the image is not distorted.
[0069]
(Modification 1 of Example 1)
The microlens array plate used in Example 1 was configured by using a general microlens whose outer shape on the XY plane was a circular shape, but was instead configured by a hexagonal microlens. A microlens array plate can also be used. FIG. 10 shows a corresponding state of the hexagonal microlens 404, the tertiary light source image 470 formed by the microlens 404, and the pixel opening 474 of the liquid crystal device 401. In this example, it is assumed that the first optical element 200 configured by arranging the light beam splitting lenses 201 in 4 rows × 4 columns is assumed. As can be seen from the figure, in this example, one microlens 404 corresponds to four pixels of the liquid crystal device 401, and a tertiary light source image 470 formed by one microlens 404. The number is 32 [Seiko 1].
[0070]
Even in such a configuration, the lens characteristics and the arrangement state of the light beam splitting lens 201 constituting the first optical element 200 and the polarization separation unit array 320 and the condensing lens array 310 constituting the second optical element 300 are adjusted. Then, by making the arrangement state of the formed secondary light source images and the arrangement state of the pixel openings 474 similar to each other, the same effect as in the case of the first embodiment can be expected.
[0071]
In addition, when the microlens array plate 402 is configured by using the hexagonal microlens 404, the microlens array plate in which the microlenses 404 are packed most closely without generating a gap between the microlenses 404 is used. Since it can be configured, the light utilization efficiency in the microlens array plate 402 can be further improved.
[0072]
Furthermore, some liquid crystal devices have pixels arranged in a delta shape, and such a liquid crystal device has a single plate that displays a color image by mounting three color filters on the pixels of one liquid crystal device. This type of liquid crystal device is often used for such a liquid crystal display device. However, for such a liquid crystal device, the arrangement state of the microlens and the arrangement state of the pixel openings are easily matched. The use of a microlens array plate composed of microlenses is optimal.
[0073]
(Modification 2 of Example 1)
It is also possible to use a microlens array plate 402 constituted by microlenses whose curved surface shape is a toric shape. The toric lens is a lens having a curved shape in which the curvature shape of the lens differs in the X-axis direction and the Y-axis direction. If this type of lens is used, the arrangement state of the third light source image 474 formed by the microlens can be changed independently between the X-axis direction and the Y-axis direction. It is not necessary to match the arrangement state of the secondary light source image formed by the optical element 300 with the arrangement state of the pixel openings 474 of the liquid crystal device 401. For example, the ratio of the arrangement pitch in the X-axis direction and the arrangement pitch in the Y-axis direction of the secondary light source image is 1: 3/4, that is, between the X-axis direction and the Y-axis direction of the light beam splitting lens in the first optical element. It may be in a state equal to the ratio of the arrangement pitch. In this case, since all the first optical elements 200 can be constituted by concentric lenses, the condensing lens array of the second optical element and the first optical element can be used in the same lens array body. Therefore, cost reduction of the optical system can be achieved.
[0074]
(Example 2)
Based on the projection display device 1 shown in the first embodiment, a three-plate projection display device using three transmissive liquid crystal devices can also be configured.
[0075]
FIG. 11 is a schematic configuration diagram showing the main part of the optical system of the projection display device 2 of this example, and shows the configuration in the XZ plane. The projection display device 2 of this example is based on the projection display device 1 shown in the first embodiment, and color light separating means for separating the white light beam into three color lights and the three color lights are synthesized there. Further, color light combining means for forming a color image is added, and the number of transmission type liquid crystal devices that form a display image by modulating each color light based on display information is increased to three.
[0076]
The projection display device 2 of this example includes a light source unit 10 that emits a random polarized light beam in one direction, and the random polarized light beam emitted from the light source unit 10 is approximately one by the secondary light source image forming unit 20. It is converted into a type of polarized light beam (S-polarized light beam in this example).
[0077]
The luminous flux emitted from the secondary light source image forming means 20 first transmits red light and reflects blue light and green light in a blue light green light reflecting dichroic mirror 461 which is a color light separating means. The red light is reflected by the reflection mirror 463, passes through the collimating lens 417, and reaches the red light liquid crystal device 411. On the other hand, of the blue light and the green light, the green light is reflected by the green light reflecting dichroic mirror 462, which is also a color light separating means, and reaches the green light liquid crystal device 412 via the collimating lens 418. Here, since the blue light has the longest optical path length among the color lights, the blue light is guided by a relay lens system including an incident lens 431, a relay lens 432, and an exit lens 433. Means 430 are provided. That is, after passing through the green light reflecting dichroic mirror 462, the blue light is first reflected by the reflecting mirror 435 through the incident lens 431, guided to the relay lens 432, and focused on this relay lens, and then reflected by the reflecting mirror 436. The light is guided to the exit lens 433 and then reaches the blue light liquid crystal device 413 through the collimating lens 419. The collimating lenses 417, 418, and 419 disposed on the light incident side of the three liquid crystal devices 411, 412, and 413 are respectively supplied from the secondary light source image forming unit 20 as described in the first embodiment. It is installed to collimate the illumination light beam. In addition, a lens in which a collimating lens 419 provided in the blue light liquid crystal device 413 and an output lens 433 of the light guide unit are integrated may be used.
[0078]
The three liquid crystal devices 411, 412, and 413 are respectively provided with microlens array plates 421, 422, and 423 on the light incident side, and secondary light sources formed in the secondary light source image forming means 20. The image is transmitted as a tertiary light source image in a corresponding pixel opening (not shown) of each liquid crystal device. That is, most of the illumination light beams incident on the respective liquid crystal devices are not blocked by the light shielding layers (not shown) of the liquid crystal devices 411, 412, and 413, and most of them are pixel openings (see FIG. (Not shown).
[0079]
The three liquid crystal devices 411, 412, and 413 modulate the respective color lights, include image information corresponding to each color light, and then enter the modulated color light into the cross dichroic prism 450 that is a color light combining unit. In the cross dichroic prism 450, a red light reflecting dielectric multilayer film and a blue light reflecting dielectric multilayer film are formed in a cross shape, and a color image is formed by synthesizing the respective modulated light beams. The color image formed here is enlarged and projected on the screen 60 by the projection lens 50 which is a projection optical system to form a projection image.
[0080]
In the projection display device 2 configured as described above, a liquid crystal device of a type that modulates one type of polarized light beam is used. Therefore, when a random polarized light beam is guided to a liquid crystal device using a conventional illumination device, about half of the random polarized light beam is absorbed by a polarizing plate (not shown) and converted to heat. However, there is a problem that a large-sized and noisy cooling device that suppresses the heat generation of the polarizing plate is necessary as well as the light utilization efficiency is low. Also in the liquid crystal device, since the area ratio per pixel occupied by the light shielding layer increases as the pixel density increases, the degree to which the illumination light beam is blocked in the light shielding layer is increased, so that the light use efficiency is poor and the liquid crystal device is also used. There is a problem that a large-sized and noisy cooling device that suppresses heat generation is necessary. However, in the projection display device 2 of this example, this problem is greatly improved.
[0081]
That is, in the projection display device 2 of the present example, the random polarized light beam emitted from the light source unit 10 is converted into almost one type of polarized light beam in the secondary light source image forming means 20, and the polarization directions thereof are aligned. Since the three liquid crystal devices 411, 412, and 413 are illuminated by the light flux, the light absorption in the polarizing plates provided in the three liquid crystal devices is very small. Further, since these polarized light beams are superimposed and coupled on the effective image forming area of the liquid crystal device, the effective image forming area is uniformly illuminated. Furthermore, since almost no light loss is involved in the generation process of the polarized light flux, almost all of the light emitted from the light source can be guided to three liquid crystal devices, and installed in three liquid crystal devices. By the microlens array plates 421, 422, and 423, most of the light incident on the liquid crystal device can pass through the pixel opening without being blocked by the light shielding layer of the liquid crystal device. Accordingly, it is possible to obtain a projected image that has extremely high light utilization efficiency, is bright, and has no brightness unevenness.
[0082]
In addition, since light absorption in the polarizing plate provided in the liquid crystal device can be extremely reduced, heat generation due to light absorption can be suppressed, and the cooling device for suppressing the temperature rise of the polarizing plate and the liquid crystal device can be greatly downsized. it can. In particular, since the light source plate 370 is disposed in the secondary light source image forming unit 20, even when a light source that emits a light beam with poor parallelism is used for the light source unit, In addition, other polarized light beams unnecessary for display on the liquid crystal device are hardly mixed. Therefore, even when a light source that emits a light beam with poor parallelism is used, the above-described excellent characteristics can be exhibited.
[0083]
From the above, even when trying to realize a projection display device capable of displaying a very bright projection image using a light source lamp with a very large light output, it can be handled by a small cooling device. The noise of the cooling device can be reduced, and a quiet and high-performance projection display device can be realized.
[0084]
Further, in the second optical element 300, two kinds of polarized light beams are spatially separated in the horizontal direction (X direction). Therefore, the amount of light is not wasted, and it is convenient for illuminating a horizontally long liquid crystal device.
[0085]
As described with respect to the first embodiment, in the projection display apparatus 2 of this example, the spread of the width of the light beam emitted from the polarization separation unit array 320 can be suppressed despite the incorporation of the polarization conversion optical element. ing. This means that when the liquid crystal device is illuminated, there is almost no light incident on the liquid crystal device with a large angle. Therefore, a bright projection image can be realized without using a projection lens system having a very small aperture with a small F number, and as a result, a small projection display device can be realized.
[0086]
In addition, as the two types of polarized light beams are separated in the lateral direction (X-axis direction) in the second optical element 300, one secondary formed by each light beam splitting lens 201 of the first optical element 200. Two secondary light source images 203 and 205 arranged in the horizontal direction from the light source image 203 can be formed. That is, since the secondary light source image 203 is doubled by the second optical element 300, in the projection display apparatus 1 of this example, only the arrangement pitch in the Y-axis direction is set to 2/3 by the second optical element 300. It is not necessary to reduce the arrangement pitch of the secondary light source images in the X-axis direction to ½. Therefore, it is not necessary to increase the degree of decentration of the lens so much, so that the incidence efficiency of the lens does not decrease and the brightness does not decrease, and the spherical aberration does not increase and the image is not distorted. In this example, since the cross dichroic prism 450 is used as the color light combining means, the apparatus can be miniaturized. In addition, since the length of the optical path between the liquid crystal devices 411, 412, and 413 and the projection lens system is short, a bright projection image can be realized even when a projection lens system having a relatively small aperture is used. Each color light has a different optical path length in only one of the three optical paths, but in this example, for the blue light having the longest optical path, the incident lens 431, the relay lens 432, and Since the light guide means 430 configured by a relay lens system including the output lens 433 is provided, color unevenness and the like do not occur.
[0087]
Note that the projection display device can also be configured by a mirror optical system using two dichroic mirrors as color light combining means. Of course, in this case as well, it is possible to incorporate the polarized illumination device of this example, and as in the case of this example, it is possible to form a bright and high-quality projected image with excellent light utilization efficiency.
[0088]
(Example 3)
Based on the projection display device 1 shown in the first embodiment, a three-plate projection display device using three reflective liquid crystal devices can also be configured.
[0089]
FIG. 12 is a schematic configuration diagram showing the main part of the optical system of the projection display device 3 of this example, and shows the configuration in the XZ plane. The projection display device 3 of this example is based on the projection display device 1 shown in the first embodiment, and includes a polarization beam splitter that changes the emission direction of the light beam according to the polarization direction, and a white light beam in three colors. Color light separating means for separating color light and color light combining means for combining three color lights to form a color image are added, and three reflective liquid crystal devices are used in place of the transmissive liquid crystal device. Yes.
[0090]
The projection display device 3 of this example includes a light source unit 10 that emits a random polarized light beam in one direction, and the random polarized light beam emitted from the light source unit 10 is approximately one by the secondary light source image forming unit 20. It is converted into a type of polarized light beam (S-polarized light beam in this example).
[0091]
The light beam emitted from the secondary light source image forming unit 20 enters the polarization beam splitter 480, is reflected by the polarization separation surface 481, changes its traveling direction by approximately 90 degrees, and enters the adjacent cross dichroic prism 450. Here, most of the light beam emitted from the secondary light source image forming means 20 is an S-polarized light beam, but a polarized light beam having a slightly different polarization direction from the S-polarized light beam (in this example, a P-polarized light beam). A polarized light beam (P-polarized light beam) having a different polarization direction may pass through the polarization separation surface 481 as it is and is emitted from the polarization beam splitter 480 (this P-polarized light beam illuminates the liquid crystal device). Not light).
[0092]
The S-polarized light beam incident on the cross dichroic prism 450 is separated into three light beams of red light, green light, and blue light according to the wavelength by the cross dichroic prism 450, and passes through the collimating lenses 417, 418, 419, respectively. The light enters the corresponding reflective liquid crystal device for red light 414, the reflective liquid crystal device for green light 415, and the reflective liquid crystal device for blue light 416. That is, the cross dichroic prism 450 functions as color light separating means for illumination light that illuminates the liquid crystal device. In the three liquid crystal devices 414, 415, and 416, microlens array plates 421, 422, and 423 are respectively arranged on the light incident side, and the illumination light beam is condensed by the microlenses on the microlens array plate. In this state, the light enters a pixel opening (not shown).
[0093]
Here, since the liquid crystal devices 414, 415, and 416 used in this example are of the reflection type, each liquid crystal device modulates each color light and simultaneously includes display information from the outside corresponding to each color light. The polarization direction of the light beam emitted from each liquid crystal device is changed, and the traveling direction of the light beam is substantially reversed. Therefore, the reflected light from each liquid crystal device is emitted partially in a P-polarized state according to display information. The modulated light beams (mainly P-polarized light beams) emitted from the respective liquid crystal devices 414, 415, and 416 pass through the microlens array plates 421, 422, and 423 and the parallelizing lenses 417, 418, and 419 again, and cross. The light enters the dichroic prism 450, is combined into one optical image, and enters the adjacent polarizing beam splitter 480 again. That is, the cross dichroic prism 450 functions as color light combining means for the modulated light beam emitted from the liquid crystal device.
[0094]
Of the light beams incident on the polarization beam splitter 480, the light beams modulated by the liquid crystal devices 414, 415, and 416 are P-polarized light beams, and thus pass through the polarization separation surface 481 of the polarization beam splitter 480 as they are. Then, an image is formed on the screen 60.
[0095]
Also in the projection display device 3 configured as described above, a liquid crystal device of a type that modulates one kind of polarized light beam is used as in the case of the projection display device 2 described above. Therefore, when a conventional illumination device that uses a randomly polarized light beam as illumination light is used, the amount of light beam separated by the polarization beam splitter 480 and guided to the reflective liquid crystal device is approximately half of the random polarized light beam. Therefore, there is a problem that it is difficult to obtain a bright projected image due to poor light utilization efficiency. However, in the projection display device 3 of this example, this problem is greatly improved.
[0096]
That is, in the projection display device 3 of the present example, the random polarized light beam emitted from the light source unit 10 is converted into almost one type of polarized light beam in the secondary light source image forming means 20, so that the polarization beam splitter Almost all of the light beam incident on 480 is guided to three reflective liquid crystal devices 414, 415, and 416 as an illumination light beam. Further, since these polarized light beams are superimposed and coupled on the effective image forming area of the liquid crystal device, the effective image forming area is uniformly illuminated. Furthermore, since almost no light loss is involved in the generation process of the polarized light flux, almost all of the light emitted from the light source can be guided to three liquid crystal devices, and installed in three liquid crystal devices. By using the microlens array plates 421, 422, and 423, most of the light incident on the liquid crystal device can be guided to the pixel openings without being blocked by the light shielding layer (not shown) of the liquid crystal device. Accordingly, it is possible to obtain a projected image that has extremely high light utilization efficiency, is bright, and has no brightness unevenness.
[0097]
Further, in the second optical element 300, two kinds of polarized light beams are spatially separated in the horizontal direction (X direction). Therefore, the amount of light is not wasted, and it is convenient for illuminating a horizontally long liquid crystal device.
[0098]
As described above with respect to the first embodiment, in the projection display device 3 of this example, the spread of the width of the light beam emitted from the polarization separation unit array 320 can be suppressed despite the incorporation of the polarization conversion optical element. ing. This means that when the liquid crystal device is illuminated, there is almost no light incident on the liquid crystal device with a large angle. Therefore, a bright projection image can be realized without using a projection lens system having a very small aperture with a small F number, and as a result, a small projection display device can be realized.
[0099]
In addition, as the two types of polarized light beams are separated in the lateral direction (X-axis direction) in the second optical element 300, one secondary formed by each light beam splitting lens 201 of the first optical element 200. Two secondary light source images 203 and 205 arranged in the horizontal direction from the light source image 203 can be formed. That is, since the secondary light source image 203 is doubled by the second optical element 300, in the projection display apparatus 1 of this example, only the arrangement pitch in the Y-axis direction is set to 2/3 by the second optical element 300. It is not necessary to reduce the arrangement pitch of the secondary light source images in the X-axis direction to ½. Therefore, it is not necessary to increase the degree of decentration of the lens so much, so that the incidence efficiency of the lens does not decrease and the brightness does not decrease, and the spherical aberration does not increase and the image is not distorted.
[0100]
In general, a reflective liquid crystal device has a feature that it is easy to ensure a somewhat high aperture ratio even when the pixel density is improved as compared with a transmissive liquid crystal device. However, in a reflective liquid crystal device, if the pixel density is very high and the pixel itself is small, the influence of the lateral electric field effect on adjacent pixels is unavoidable. The part must be made smaller. Therefore, even when a reflective liquid crystal device is used, the optical configuration of the present invention can sufficiently exhibit its excellent characteristics.
[0101]
In this example, the cross dichroic prism is used as the color light separating means and the color light synthesizing means, but the projection display device can also be configured by using two dichroic mirrors instead. Of course, in this case as well, it is possible to incorporate the polarized illumination device of this example, and as in the case of this example, it is possible to form a bright and high-quality projected image with excellent light utilization efficiency.
[0102]
【The invention's effect】
As described above, according to the present invention, it is possible to significantly increase the amount of light flux incident on each pixel opening of a modulation means such as a liquid crystal device. Therefore, the light utilization efficiency in the modulation means can be greatly improved, and there is an effect that it is possible to realize a projection display apparatus that can obtain a bright projection image without uneven brightness.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an optical system of a projection display apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a perspective view of a first optical element according to Embodiment 1 of the present invention.
FIG. 3 is a diagram illustrating a position of a lens optical axis of a light beam splitting lens constituting a first optical element.
FIG. 4 is a diagram illustrating an arrangement state of secondary light source images formed by a first optical element.
FIG. 5 is a perspective view of a light shielding plate according to Embodiment 1 of the present invention.
6 is a perspective view of a polarization beam splitting unit array according to Embodiment 1 of the present invention. FIG.
FIG. 7 is a diagram for explaining the function of the polarization separation unit according to the first embodiment of the invention.
FIG. 8 is a diagram illustrating an arrangement state when a secondary light source image formed inside the polarization separation unit array is viewed from the liquid crystal device side.
FIG. 9 is a cross-sectional view showing a schematic structure of a liquid crystal device provided with the microlens array plate of Example 1 of the present invention.
10 is a diagram for explaining a positional relationship between a microlens of a liquid crystal device portion, a tertiary light source image, and a pixel opening portion in Modification Example 1 of Embodiment 1 of the present invention.
FIG. 11 is a schematic configuration diagram showing an optical system of a projection display apparatus according to Embodiment 2 of the present invention.
FIG. 12 is a schematic configuration diagram showing an optical system of a projection display apparatus according to Embodiment 3 of the present invention.
[Explanation of symbols]
1, 2, 3 Projection display device
10 Light source
20 Secondary light source image forming means
40 Liquid crystal device
50 Projection lens
60 screens
101 Light source lamp
102 Parabolic reflector
200 First optical element
201 luminous flux splitting lens
202 Intermediate luminous flux
203 Condensed image (secondary light source image)
Secondary light source image with 204 P-polarized light beam
205 Secondary light source image with S-polarized light beam
210 Lens optical axis
300 Second optical element
310 Condensing lens array
311 condenser lens
320 Polarized light separation unit array
330 Polarization Separation Unit
331 Polarization separation surface
332 reflective surface
333 P emission surface
334 S exit surface
335 P-polarized light flux
336 S-polarized light flux
370 Shading plate
371 Shading surface
372 Open surface
380 Selective phase difference plate
381 λ / 2 retardation plate
390 coupled lens
401 Liquid crystal device
402 Microlens array plate
403, 404 Micro lens
405 collimating lens
406 Output-side condenser lens
411 Liquid crystal device for red light (transmission type)
412 Liquid crystal device for green light (transmission type)
413 Blue light liquid crystal device (transmission type)
414 Red light liquid crystal device (reflection type)
415 Liquid crystal device for green light (reflection type)
416 Blue light liquid crystal device (reflection type)
417, 418, 419 Parallelizing lens
421, 422, 423 Micro lens array plate
430 Light guide means
431 Incident lens
432 Relay lens
433 Exit lens
435, 436 Reflective mirror
450 Cross Dichroic Prism
461 Blue light green light reflection dichroic mirror
462 Green light reflection dichroic mirror
463 reflection mirror
470 Tertiary light source image
471 LCD substrate
472 Liquid crystal layer
473 shading layer
474 pixel aperture
475 Counter substrate
476 Microlens substrate
480 Polarizing beam splitter
481 Polarization separation surface

Claims (16)

A light source;
First secondary light source image forming means for forming a plurality of first secondary light source images on substantially the same plane from the light emitted from the light source;
A second secondary light source that forms a second secondary light source image obtained by doubling the plurality of first secondary light source images formed by the first secondary light source image forming unit on substantially the same plane. Light source image forming means;
Tertiary light source image forming means for forming a tertiary light source image from the second secondary light source image formed by the second secondary light source image forming means on substantially the same plane;
Modulation means for modulating light emitted from the tertiary light source image forming means by a pixel;
The ratio of the vertical arrangement pitch and the horizontal arrangement pitch of the tertiary light source image is substantially the same as the ratio of the vertical arrangement pitch and the horizontal arrangement pitch of the pixels. A projection display apparatus, wherein the optical characteristics of the secondary light source image forming means or the tertiary light source image forming means are determined. In claim 1,
The ratio of the vertical arrangement pitch and the horizontal arrangement pitch of the second secondary light source image is substantially the same as the ratio of the vertical arrangement pitch and the horizontal arrangement pitch of the pixels. A projection display apparatus, wherein optical characteristics of the first secondary light source image forming means are determined. In claim 1,
The ratio between the half of the vertical arrangement pitch of the first secondary light source image and the horizontal arrangement pitch is the ratio of the vertical arrangement pitch of the pixels of the modulation means to the horizontal arrangement pitch. The projection type display apparatus is characterized in that the optical characteristics of the first secondary light source image forming means are determined so as to be substantially the same. In any one of Claim 1 to 3,
The first secondary light source image forming means includes a plurality of rectangular light beam splitting lenses arranged on substantially the same plane,
A projection display apparatus, wherein an aspect ratio of the rectangular beam splitting lens is substantially the same as an aspect ratio of an illuminated area of the modulating means. In any one of Claim 1-4,
Color separation means for separating light emitted from the light source into two or more color lights;
A plurality of said modulation means for modulating each color light separated by said color light separation means;
Color light combining means for combining the respective color lights modulated by the respective modulation means;
A projection display system, comprising: a projection optical system that projects the color light synthesized by the synthesis unit. A light source;
A light beam splitting unit that splits an incident light beam from the light source into a plurality of intermediate light beams to form a plurality of light source images;
A polarization separation unit that separates each of the plurality of intermediate light beams into polarized light beams having two types of polarization directions, and a polarization conversion unit that aligns the polarization directions of the two types of polarized light beams separated by the polarization separation unit. Polarization generating means;
Modulation means having a microlens disposed on the polarized light generation means side,
The modulating means comprises a plurality of pixels;
The ratio between the vertical arrangement pitch and the horizontal arrangement pitch of the light source image formed by the microlens is substantially the same as the ratio between the vertical arrangement pitch and the horizontal arrangement pitch of the pixels. An optical characteristic of the light beam splitting means or the microlens is determined. In claim 6,
The ratio between the vertical arrangement pitch and the horizontal arrangement pitch of the light source image formed by the polarized light generating means is substantially the same as the ratio between the vertical arrangement pitch and the horizontal arrangement pitch of the pixels. In addition, an optical characteristic of the light beam splitting means is determined. In claim 6,
The ratio of the vertical array pitch of the plurality of light source images formed by the light beam splitting means to the horizontal array pitch is substantially the same as the ratio of the vertical array pitch and the horizontal array pitch of the pixels. A projection display apparatus, wherein optical characteristics of the light beam splitting means are determined so as to be the same. In any of claims 6 to 8,
The beam splitting means includes a plurality of rectangular beam splitting lenses arranged on substantially the same plane,
A projection display apparatus, wherein an aspect ratio of the rectangular beam splitting lens is substantially the same as an aspect ratio of an illuminated area of the modulating means. In claim 9,
A projection display device, wherein a part or all of the light beam splitting lens is an eccentric lens. In any of claims 6 to 8,
The beam splitting means is
A first lens plate comprising a plurality of concentric lenses arranged on substantially the same plane;
A projection display device comprising: a second lens plate comprising a plurality of cylindrical lenses arranged on substantially the same plane. In claim 6,
A projection display device, wherein a part or all of the microlens is a toric lens. In any of claims 6 to 12,
The polarization separation means includes
A polarization separation surface that separates each of the plurality of intermediate light beams into polarized light beams having two types of polarization directions, and two types of polarized light beams that are formed in parallel with the polarization separation surface and separated by the polarization separation surface. A projection display device comprising a plurality of polarization separation units each having a reflecting surface for emitting one of the polarized light beams in the substantially same direction as that of the other polarized light beam. In any of claims 6 to 13,
The projection display device, wherein the microlens is constituted by a refractive index distribution type microlens. In any of claims 6 to 14,
The projection display device according to claim 1, wherein the microlens is constituted by a close-packed microlens. In any of claims 6 to 15,
Color light separation means for separating light emitted from the light source into two or more color lights;
A plurality of said modulation means for modulating each color light separated by said color light separation means;
Color light combining means for combining the respective color lights modulated by the respective modulation means;
And a projection optical system for projecting each color light synthesized by the color synthesis means.

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