JPH1055025A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device capable of performing time division display and displaying a picture with high resolution by simple constitution without lowering the transmissivity of light and contrast even when an optical modulation element having a small number of picture elements is used in the case of displaying the picture by dividing the picture of one frame into plural fields. SOLUTION: By driving an actuator 5 (5a1, 5a2 and 5b1) synchronizing with a field signal supplied to the optical modulation element 3, a microlens array 4 is moved in horizontal and vertical directions orthogonal to the optical axis of the light made incident on the microlens array 4. A light shielding plate 6 is arranged on an optical path leading to a projection lens 7 from the microlens array 4 and equipped with a light transmitting area 61 transmitting the light which straight advances to be transmitted through the element 3 and is condensed by a convex lens and a light shielding part 62 shielding the light which is scatteringly transmitted through the element 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection display device for obtaining a large-screen display by enlarging and projecting an image displayed on a light modulation element, and more particularly to a projection display in which an image of one frame is divided into a plurality of fields and displayed. The present invention relates to a type display device.

[0002]

2. Description of the Related Art FIG. 9 shows a schematic configuration of a conventional typical projection display device. In FIG. 9, 1 is a light source, 3 is a light modulation element, 8 is a projection lens, and 9 is a screen. A transmissive liquid crystal panel is used for the light modulation element 3 of the projection display device. As the light source 1, a metal halide lamp or a halogen lamp having a relatively uniform spectrum in a visible light region is used. An image is formed by performing light modulation according to an image signal on the light of the light source 1 condensed by a reflector or the like using a light modulation element 3 such as a liquid crystal panel. The formed image is enlarged and projected on the screen 9 by the projection lens 8 and displayed.

A projection display device can display a large area as compared with other display devices because an image is enlarged and projected by a projection lens, but has a problem of low resolution. The resolution of the projected image is determined by the number of pixels of the light modulation element and the size of the screen. In order to display a high-resolution image on a screen, it is necessary to increase the number of pixels of the light modulation element. However, when the number of pixels is increased, the manufacturing yield is reduced and the cost is increased. For example, SXGA (1280 × 102
The light modulation element having the number of pixels of 4) is a VGA (640 × 48
The cost is about 10 times that of the light modulation element having the number of pixels 0). In addition, the aperture ratio per pixel (the ratio of the effective area that transmits light to one pixel) decreases as the density of the pixels increases, so that it is difficult to obtain an image with a desired brightness. As described above, since the density of the pixels and the brightness of the image are in conflict with each other, a high-quality image cannot be obtained by simply increasing the density of the pixels of the light modulation element.

[0004] In order to solve this problem, there is a method of projecting using a plurality of light modulation elements. In the method using a plurality of light modulation elements, for example, a plurality of images are displayed vertically and horizontally using a plurality of display units like a multi-vision using a CRT (cathode ray tube) on a display device. However, in this method, since a plurality of display units are used, there is a problem that a screen cannot be made continuous at a connection portion of each display unit and a boundary is conspicuous. In addition, since it is difficult to manufacture a plurality of display units with exactly the same display characteristics, there is a problem that brightness of each display unit becomes uneven, and a joint between the display units becomes conspicuous. I have.

[0005] In order to solve this problem, a method of superimposing and displaying one image by using a plurality of display units is known. The projection display device described in Japanese Patent Application Laid-Open No. 3-166536 discloses an image distribution function unit that arbitrarily samples and divides display data of an original image, a plurality of display function units, and optically converts each display image. An image synthesizing function unit that synthesizes and displays an original image, and a projection function unit that projects a synthesized image are provided. FIG. 10 shows the basic configuration. FIG.
In the figure, 8 is a projection lens, 11 is a light supply unit composed of a plurality of light sources, 12 is a light modulation element group composed of a plurality of transmissive liquid crystal panels, and 13 is a composite image projected by the light modulation element group 12 and projected. This is an optical device for making the light enter the lens 8. For example, when superimposed display is performed using four transmissive liquid crystal panels 12, the aperture ratio of each pixel of each transmissive liquid crystal panel 12 is set to about 25%, and the projection is performed by shifting by a half pixel pitch in the horizontal and vertical directions. By doing so, it is possible to obtain an image with four times the resolution. FIG.
FIG. 11B shows four images as shown in FIG.
11A is shifted by a half pixel pitch in the horizontal direction with respect to the image of FIG. 11A, and the image of FIG. 11C is shifted by a half pixel pitch in the vertical direction with respect to the image of FIG.
If the image of (d) is projected with a half pixel pitch shift in the horizontal and vertical directions with respect to the image of FIG.
An image having four times the resolution as shown in FIG. 11E is obtained. By performing the superimposed display in this way, the non-uniformity of the display characteristics of the plurality of display units can be made inconspicuous. However, there is a problem in that it is difficult to adjust an optical system for projecting the images with a half pixel pitch shifted from each other, and in that a plurality of display units are used, so that the configuration is complicated and the cost is high.

As another means for increasing the resolution, there is a method of performing time-division display using one light modulation element. Time-division display is a method of displaying one field (one screen) by displaying a plurality of fields in time series. For example, JP-A-4-
The projection display device described in JP-A-113308 shifts a projected image by using an element for turning the polarization direction of transmitted light in the optical path from the light modulation element to the screen and a transparent element having a birefringence effect. Means and means for discrete projection on the screen. FIG. 12 shows a basic configuration of the projection display device. In FIG. 12, 1 is a light source, 3 is a light modulating element composed of a liquid crystal panel for display, 14 is a liquid crystal panel for controlling the polarization direction, 15 is a quartz plate, and 8 is a projection lens. A quartz plate 15 is used as a transparent element having a birefringence effect. In this method, one frame of image data is divided and stored in a frame memory, and time-division display is performed by displaying an image in synchronization with a means for shifting a projected image. Further, a high-resolution display is performed by shifting the image in time series so as to interpolate the discretized image by using means for making the image of the light modulation element discrete.

As means for making the image discrete, there are a means for lowering the effective aperture ratio by blocking a part of a pixel, and a means for condensing light by using a microlens corresponding to one pixel. Means for shielding a part of the pixel, for example, by devising the arrangement of the wiring of the switching element provided in each pixel to reduce the light transmission area, to make the light transmission area of the pixel discrete I have. On the other hand, the means for condensing light using a microlens corresponding to one pixel condenses the light emitted from the pixel, thereby substantially discretizing the image without reducing the amount of light.

The means for shifting the projected image utilizes the birefringence effect. Using a crystal with optical anisotropy,
An image is shifted on a screen by a difference in refraction angle between ordinary light and extraordinary light. Here, a TN (twisted nematic) liquid crystal is used to rotate linearly polarized light by 90 degrees to switch between ordinary light and extraordinary light for a transparent element having a birefringence effect. Ordinary light perpendicularly incident on a transparent element having a birefringence effect goes straight, while extraordinary light is refracted by a predetermined angle on the incident surface and refracted by the same angle on the exit surface on the opposite side.
Due to this effect, the extraordinary light is shifted by a distance corresponding to the thickness of the transparent element with respect to the ordinary light. Therefore, if the thickness of the transparent element is set so as to shift by a distance corresponding to the pixel pitch (1/2 of the pixel pitch), a shift amount for interpolating a discretely formed image can be obtained.

[0009]

In the above-described time-division display, a polarization direction turning element and a transparent element having a birefringence effect as means for projecting at least discretely and means for shifting an image are required. By using one set of the polarization direction rotating element and the transparent element having the birefringence effect, the display can be divided into two fields in the horizontal or vertical direction, but the display can be divided into more fields in the horizontal or vertical direction. When the display is performed in two fields in both the horizontal and vertical directions, or when the display is divided into more fields in both the horizontal and vertical directions, the polarization direction rotating element and the birefringence are used. There is a problem that a plurality of sets of transparent elements having an effect are required, and the configuration of the plurality of elements is complicated.

Further, the method of shading a part of the pixel as a means for making the image discrete is easy to produce by simply making a slight change to the conventional liquid crystal panel, so that the structure becomes complicated. However, since a part of the pixel is shielded from light and the light transmission area is reduced, the image becomes darker than a conventional liquid crystal panel.

Although the birefringence effect is used as a means for shifting an image, the light emitted from the light modulator must be linearly polarized in order to use the birefringence effect.
To convert natural light into linearly polarized light, a polarizing plate is necessary, but the light is absorbed by the polarizing plate at about 60%, and only about 40% is transmitted. Furthermore, since a liquid crystal element is used as the means for rotating the polarization direction, light transmittance in the liquid crystal element becomes a problem. The liquid crystal element of the polarization direction rotating means is constituted by sandwiching liquid crystal between two glass substrates on which transparent electrodes are formed. The light transmittance of the transparent electrode is 90 per sheet.
%, The transmittance is about 80% for two sheets. Further, in consideration of the transmittance of the liquid crystal itself, the glass substrate, the quartz plate, and the like, the transmittance of light by the polarization direction rotating means is further reduced to about 65%. Further, in the case where resolution is increased in both the horizontal direction and the vertical direction, two sets of the polarization direction turning means and the quartz plate are required, so that the light transmittance is further reduced to about 40%. I will. Therefore, the transmittance of the light passing through the polarizing plate and the polarization direction rotating means for converting natural light into linearly polarized light is about 15 to 20%, which makes it possible to increase the resolution, but the light use efficiency is extremely high. Only a dark image is obtained, which is reduced.

Although TN liquid crystal is used as the light turning means, its responsiveness becomes a problem. The TN liquid crystal switches the orientation of molecules by turning on and off the voltage, and its response (switching time) is several milliseconds. When one frame (1/60 to 1/30 seconds) is divided into a plurality of fields when performing time-division display, the number of
Since it takes ten and several milliseconds, when the TN liquid crystal is used, the switching time of the polarization direction occupies several tens of% in one field. As a result, there arises a problem that the contrast of the image is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art.
It is an object of the present invention to provide a projection display device that can perform time-division display with a simple configuration without reducing light transmittance and contrast even when a light modulation element having a small number of pixels is used and display an image with high resolution.

[0014]

The object of the present invention is to provide a projection display device in which an image displayed by a light modulation element having a plurality of pixels is enlarged and projected on a screen by a projection means.
The light emitted from a predetermined number of adjacent pixels among the plurality of pixels of the light modulation element is located on the light path from the light modulation element to the projection unit, and the image on the screen is separated into a plurality of pixels. A plurality of condensing optical elements arranged adjacent to each other within a diameter of the condensing optical element, and a plurality of light transmitting areas for transmitting light emitted from the condensing means of light incident substantially parallel to the optical axis of the condensing optical element. And a light-shielding unit having a light-shielding region for shielding light other than the emitted light, and an image-modulating area on the screen by changing an image projection area on the screen so as to interpolate an image separated on the screen by the light-collecting unit. This is achieved by a projection display device comprising: a projection area changing unit for projecting an image to be displayed; and performing time-division display in which one frame is composed of a plurality of fields.

The above object is also achieved by a microlens array in which the light condensing means has a plurality of convex lenses including, within respective apertures, outgoing light from adjacent (i × j) pixels among the plurality of pixels of the light modulation element. Wherein the light-shielding means is located near the focal plane of the light-collecting means, and the light-transmitting region of the light-shielding means is arranged at an interval substantially equal to the pixel pitch of the light modulation element.
This is achieved by a projection display device characterized by being arranged in a dimension.

It is another object of the present invention to provide a lenticular, wherein the light condensing means has a plurality of semi-circular cross-sectional microlenses including, within respective apertures, outgoing light from adjacent i-line pixels among the plurality of pixels of the light modulation element. Lens array,
A projection type display device, wherein the light-shielding means is located near the focal plane of the light-collecting means, and the light-transmitting regions of the light-shielding means are arranged in stripes at intervals substantially equal to the pixel pitch of the light modulation element. Achieved by

Further, the light modulation element is characterized by being a liquid crystal polymer composite having a transmission scattering mode.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection display according to a first embodiment of the present invention will be described with reference to FIGS. The projection display device according to the present embodiment separates an image into a plurality of pixels on a screen in order to increase the definition of a projected display image without increasing the number of pixels of a light modulation element such as a liquid crystal light valve for display. A light-collecting means in which a plurality of light-collecting optical elements each including light emitted from a plurality of pixels adjacent to the light-modulating element within their respective apertures are arranged, and a light-collecting element that is incident substantially parallel to the optical axis of the light-collecting optical element. A light-shielding unit having a plurality of light-transmitting regions for transmitting light emitted from the light unit and a light-shielding region for shielding light other than the emitted light; and light interpolating an image separated on the screen by the light-collecting unit. By a projection area changing means for projecting a display image by the modulation element,
Basically, time-division display is performed by discretely reducing light emitted from a light modulation element and interpolating a discrete gap. In the projection type display device according to the present embodiment, a light source, a condensing optical component, a light modulation element such as a liquid crystal light valve for display composed of a large number of pixels arranged two-dimensionally, and a conventional light source such as a projection lens. In addition to the components used in the projection display device, on the optical path from the light modulating element to the projecting means, a light collecting means for condensing outgoing light from the light modulating element for each of a plurality of pixels and discretely reducing the light is provided. The gap image is interpolated by moving the focusing means or the projection means in a plane perpendicular to the incident optical axis in synchronization with a field signal supplied to the light modulation element, the gap which has been discretely reduced. To increase the number of pixels / high definition of the displayed image. Furthermore, on the optical path from the condensing unit to the projecting unit, a light shielding unit having a plurality of light transmitting regions for transmitting light emitted from the condensing unit of light incident parallel to the optical axis of the condensing optical element is provided. In addition, it is possible to shield scattered light from the light modulation element.

In the present embodiment, a description will be given of a case where each of a plurality of pixels adjacent to the light modulating element has four pixels, and a plurality of condensing optical elements including the light emitted from the four pixels within the aperture are convex lenses. I do.

FIG. 1 is a basic configuration diagram of a projection type display device according to the present embodiment, FIG. 2 is a perspective view of a microlens array used in the present embodiment, and FIG. 3 shows a positional relationship between a light modulation element and a convex lens. FIGS. 4 and 5 are cross-sectional views taken along the line AA 'of FIG. 3 for explaining the operation of the light shielding plate. FIG. 6 shows the positional relationship of the incident light flux on the object plane of the projection lens when one screen is divided into four images.

In FIG. 1, 1 is a light source, 2 is a collimating conversion lens for converting light from the light source into parallel light, 3
Is a light modulation element composed of a large number of pixels arranged two-dimensionally, 4 is a microlens array, 5 is an actuator composed of a piezoelectric element, 6 is a light shielding plate having a light transmitting area, 8 is a projection lens, 7 Denotes an object plane of the projection lens 8, and 9 denotes a screen. The micro lens array 4 is arranged on an optical path from the light modulation element 3 to the projection lens 8, and one convex lens is formed corresponding to four pixels of the light modulation element 3. The actuator 5 includes the microlens array 4
Actuators 5a1 and 5a2 that vibrate in the vertical direction (vertical direction on the paper) and actuators 5b1 and 5b2 (not shown) that vibrate in the horizontal direction (the normal direction on the paper). The microlens array 4 is moved or vibrated in a horizontal / vertical direction orthogonal to the optical axis of light incident on the microlens array 4 by driving the actuator 5 in synchronization with a field signal supplied to the light modulation element 3. Is available. Light shield plate 6
Is disposed on the optical path from the microlens array 4 to the projection lens 8 and scatters the light modulating element 3 through a light transmitting area 61 which passes straight through the light modulating element 3 and transmits light collected by the convex lens. And a light-shielding portion 62 for shielding transmitted light.

The light modulation element 3 used in the present embodiment has p
This is an active matrix type liquid crystal light valve using an poly-Si TFT (thin film transistor using polycrystalline silicon for a channel layer). A liquid crystal polymer composite (Liquid Crystal Polymer C) which does not require a polarizing plate is used as a liquid crystal material of a liquid crystal light valve.
omposite). The number of pixels of the light modulation element 3 is m × n, and the pixel pitch p is 50 μm, which is a general value both horizontally and vertically.

The microlens array 4 shown in FIG. 2 is formed by using, for example, an ion exchange method. First, a metal thin film as a mask material for an ion exchange process is deposited on a glass substrate containing alkali ions such as sodium ions (Na +) by sputtering. Next, windows for ion exchange are opened in the metal thin film by photolithography at an interval (100 μm pitch) twice the pixel pitch p of the light modulation element 3. This is immersed in a molten salt containing another type of metal ion for a certain period of time. At this time, the alkali ions in the glass substrate and another type of metal ions in the molten salt are exchanged by mutual diffusion, and a hemispherical region having a different refractive index is formed in the glass substrate, which is used as a lens effect. Use. The micro lens 41 made of the convex lens manufactured by the above process is designed to collect as much as possible the light beams emitted from the four pixels. Finally, the metal mask is removed. Since the size of the microlens array 4 can be substantially the same as the size of the light modulation element 3, its weight can be reduced to about several grams.

The actuator 5 uses a laminated piezoelectric element made of a high distortion piezoelectric ceramic material. The actuator 5 is adhered to the side surface of the microlens array 4, and a voltage is applied in synchronization with a field signal supplied to the light modulation element 3, so that a horizontal / vertical direction perpendicular to the optical axis of light incident on the microlens array 4 is obtained. The micro lens array 4 can be moved and changed in the direction.

The light shielding plate 6 is formed, for example, by providing a light shielding portion on a glass substrate. First, a metal thin film serving as a light shielding portion is deposited on a glass substrate by sputtering. Next, a window serving as a light transmission region 61 is opened in the metal thin film by photolithography at a pixel pitch p (pitch of 50 μm) of the light modulation element 3. According to this method, a window having a small diameter can be accurately manufactured.

The relative positional relationship between the light modulation element 3 and the microlens array 4 is, for example, at the position shown in FIG.
Microlenses 41 are provided so as to correspond to four adjacent pixels of the light modulation element 3. The light shielding plate 6 is shown in FIG.
It is located between the microlens array 4 and the projection lens 8 (not shown) as shown in FIG. In the present embodiment, a liquid crystal polymer composite having a transmission scattering mode is used for the light modulation element 3. In this display element, when the light modulation element 3 is in the ON state (FIG. 4A), a voltage is applied to the cell, so that the liquid crystal is directed in the direction of the electric field and the light that is perpendicularly incident on the cell is transmitted as it is. I do. The light transmitted straight through the light modulation element 3 is condensed by the microlens 41, transmitted through the light transmission area 61 of the light shielding plate 6, and guided to the projection lens 8. on the other hand,
When the light modulation element 3 is in the OFF state (FIG. 4B),
Since no voltage is applied to the cell, the liquid crystal molecules are oriented in random directions. Therefore, the refractive index becomes discontinuous, and the light incident on the light modulation element 3 is strongly scattered. Therefore, part of the light is transmitted as scattered light, and part of the light is reflected as scattered light on the incident side. At this time, the light transmitted through the light modulation element 3 is transmitted to the micro lens 41 of the micro lens array 4.
Is refracted in various directions. If this scattered light reaches the object surface 7 of the projection lens and enters the projection lens 8, it is displayed on a screen and lowers the contrast. In the present embodiment, since the light-shielding plate 6 having the light-transmitting region 61 is provided, the light that travels straight through the light modulation element 3 and is transmitted is condensed by the microlens 41, and the light-transmitting region 61 of the light-shielding plate 6 The transmitted light and the scattered light are
Therefore, a bright and high-contrast image can be displayed. At this time, the smaller the light transmitting area 61 is, the more scattered light is blocked and a high-contrast image can be displayed. The optimum area of the light transmission region 61 can be obtained from the numerical aperture of the lens unit and the thickness of the microlens array 4 substrate. For example, when the condensing optical element is a microlens 41 with NA = 0.11 (collection angle: 6.6 °), the focal length is 0.432 mm. The lens array 4 is manufactured, and the light shielding plate 6 is
If the diameter of the light transmission area 61 of the light shielding plate 6 is set to about 10 μm,
A bright and very high-contrast image can be displayed. The light shielding plate 6 is not provided with the light transmitting region 61 that transmits light only in the case of FIG.
(A)-(d) In order to transmit light in all cases, the light transmitting region 6 is located at the vertex of each pixel of the light modulating element 3.
1 is provided.

The operation of shifting the image by the microlens array 4, the actuator 5, and the light shielding plate 6 to display a high-definition image in the present embodiment will be described with reference to FIGS.
This will be described with reference to FIG. In the present embodiment, one screen (frame) is divided into four images (fields) and displayed. Although the actual planar shape of each microlens is a rectangular shape including the entire four pixels within the aperture as shown in FIG. 2, the position of each microlens is clearly shown in the plan views of FIGS. Each microlens is indicated by a solid or broken circle.

Now, in the first field of the first frame, the relative position between the pixel of the light modulation element 3 and the micro lens 41 is as shown in FIG. For example, the central axis of the micro lens 41 is the pixel 1 of the light modulation element 3,
The light emitted from the pixels 1, 2, 5, and 6 is located at the intersection of 2, 5, and 6, and is collected by one microlens 41. As shown in FIG. 5A, the light beams 101 and 102 emitted from the pixels 5 and 9 when the light modulation element 3 is in the ON state,
The light is condensed by the microlens array 4, becomes outgoing light 101 ′, 102 ′ that has passed through the light transmitting region 61 of the light shielding plate 6, and enters the projection lens 8. At this time, the light incident parallel to the optical axis of the microlens 41 is applied to the light shielding portion 62 of the light shielding plate 6.
No light is lost because the light enters the projection lens 8 without being shielded from light. On the other hand, the transmitted light scattered by the light modulation element 3 is shielded by the light-shielding portion 62 of the light-shielding plate 6 as shown in FIG. 4, so that a decrease in image contrast on the screen can be prevented. The object surface 7 of the projection lens 8 is set at a position where the light from the light modulation element 3 is condensed to approximately 1/4. The image displayed on the object plane 7 of the projection lens is shown in FIG.
As shown in (a), the state is thinned out in each of the horizontal and vertical directions, that is, the state is discretely reduced.

Next, in the second field, the actuator 5a vibrates in the vertical direction in synchronization with the field signal.
The microlens array 4 is moved in the direction perpendicular to the optical axis of the light incident on the microlens array 4 in the direction perpendicular to the microlens array 4 by 1 and 5a2. The central axis of the micro lens 41 moves to the position of the intersection of the pixels 5, 6, 9, and 10 of the light modulation element 3, that is, the position of FIG. Here, the movement amount of the microlens array 4 from the position of FIG. 3A to the position of FIG. 3B is 50 μm, which is the same as the pixel pitch p of the light modulation element 3. At this time, as shown in FIG.
The outgoing lights 101 and 102 from the pixels 5 and 9 when the light modulating element 3 is in the ON state are condensed by the microlens array 4 and pass through the light transmitting area 61 of the light shielding plate 6 to emit the outgoing light 101 ″. , 102 "and enter the projection lens 8. At this time, similarly to the first field, the light incident parallel to the optical axis of the microlens 41 is applied to the light shielding portion 6 of the light shielding plate 6.
Since the light enters the projection lens 8 without being shielded by the light 2, there is no light loss. When the light modulation element 3 is in the OFF state, the light-shielding portion 62 of the light-shield
The scattered light which is blocked by the above and lowers the contrast does not enter the projection lens 8. In the object plane 7 of the projection lens 8, the light is condensed at the position shown in FIG. 6B, and the vertical gap discretely reduced in the first field by the microlens array 4 is interpolated in the second field. It was done.

Next, in the third field, the actuator 5b vibrates in the horizontal direction in synchronization with the field signal.
The microlens array 4 is moved in the horizontal direction within a plane orthogonal to the optical axis of the light incident on the microlens array 4 by the steps 1 and 5b2. The central axis of the micro lens 41 moves to the position of the intersection of the pixels 6, 7, 10, and 11 of the light modulation element 3, that is, the position of FIG. Here, the amount of movement of the microlens array 4 from the position in FIG. 3B to the position in FIG. 3C is 50 μm, which is the same as the pixel pitch p of the light modulation element 3. As a result, the light emitted from the light modulation element 3 is focused on the object plane 7 of the projection lens at the position shown in FIG.
This means that the horizontal gap portion discretely reduced in the second field by the microlens array 4 is interpolated in the third field.

Next, in the fourth field, the actuator 5a vibrates in the vertical direction in synchronization with the field signal.
The microlens array 4 is moved vertically in a plane perpendicular to the optical axis of the light incident on the microlens array 4 by the steps 1 and 5a2. The central axis of the micro lens 41 is the position of the intersection of the pixels 2, 3, 6, and 7 of the light modulation element 3, that is, FIG.
Move to position (d). Here, the movement amount of the microlens array 4 from the position of FIG. 3C to the position of FIG. 3D is 50 μm, which is the same as the pixel pitch p of the light modulation element 3. As a result, the light emitted from the light modulation element 3 is focused on the object plane 7 of the projection lens 8 at the position shown in FIG.
The vertical gap discretely reduced in the third field by the microlens array 4, that is, the horizontal gap discretely reduced in the first field is interpolated in the fourth field. .

By the first, second, third and fourth fields described above, the image information of all one frame is shown in FIG.
As shown in FIG.
, And high-definition display can be realized using the light modulation element 3 with low definition.

Next, in the first field of the second frame, the actuators 5b1 and 5b2 which vibrate in the horizontal direction in synchronization with the field signal horizontally move in a plane orthogonal to the optical axis of the light incident on the microlens array 4. The micro lens array 4 is moved in the direction. Micro lens 41
Move to the position of the intersection of the pixels 1, 2, 5, and 6 of the light modulation element 3, that is, the position of FIG. Here, FIG.
The amount of movement of the microlens array 4 from the position (d) to the position in FIG. 3A is 50 μm, which is the same as the pixel pitch p of the light modulation element 3. As a result, the light emitted from the light modulation element 3 is collected on the object plane 7 of the projection lens 8 at the position shown in FIG. 6A, and returns to the same position as the first field of the first frame. Thereafter, by interpolating the discretely reduced horizontal / vertical gaps as in the first frame, (m
× n) 4 × (m × n) using light modulation element 3 having pixels
A high-definition display having pixels is realized.

Here, four adjacent pixels are displayed in a time-division manner. However, if four field images are displayed within a short period of about one frame period (1/30 msec) of a normal television image, human Can be viewed as one high-definition image due to the afterimage effect of the eye.

In the conventional projection display device, it was possible to display on the screen 9 only at a resolution determined by the number of pixels of the light modulation element 3, but according to the present embodiment, the horizontal / vertical resolution is changed to the light modulation element. It is possible to display at twice the resolution determined by the number of pixels of 3. Since the microlens array 4 is used as a means for making the image discrete, the light use efficiency is not reduced unlike the means for blocking the light emitted from the light modulation element 3. In addition, since the gap is interpolated by mechanical vibration of the actuator 5, an optical system with light absorption, such as a polarizing plate or a liquid crystal panel for rotating a polarization direction for shifting an image, is used for the light modulation element 3. Since it does not exist on the optical path from to the projection lens 8, a bright and high-definition image can be displayed without lowering the light use efficiency. Also, the light modulation element 3
The light scattered and transmitted by the light shielding portion 62 of the light shielding plate 6
Therefore, a bright and high-definition image with excellent contrast can be displayed.

In this embodiment, the micro lens 4
After focusing by 1, the light emitted from the light modulating element is 1
Although the position where the light is condensed at / 4 is set as the position of the object plane 7 of the projection lens, it may be a position where the light emitted from the light modulation element before being focused is condensed at ４. Absent. At this time, since the image forming position of each field on the object plane 7 of the projection lens is different, the image forming position on the screen is also different.

In this embodiment, one frame is formed by four fields by using a microlens array 4 composed of a plurality of microlenses corresponding to four pixels (2 × 2 pixels) of the light modulation element 3. Configuration,
A plurality of microlenses corresponding to (i × j) pixels such as 9 pixels (3 × 3 pixels) or 16 pixels (4 × 4 pixels), or 6 pixels (2 × 3 pixels) or 12 pixels (3 × 4 pixels) One frame may be formed in (i × j) fields using the microlens array 4 composed of. At this time, the horizontal / vertical movement amounts Lh and Lv of the microlens array 4 with respect to one field signal by the actuator 5 are represented by i representing the number of pixels of the microlens corresponding to a plurality of pixels in the horizontal direction and corresponding to the vertical direction. When the number of pixels to be performed is j, the pixel pitch in the horizontal direction is ph, and the pixel pitch in the vertical direction is pv, ph ≦ Lh ≦ (i−1) × ph pv ≦ Lv ≦ (J-1) × pv.

In this embodiment, the actuator 5 uses a laminated piezoelectric element made of a high-strain-rate piezoelectric ceramic material, but the microlens array is synchronized with the frequency of a field signal supplied to the light modulation element 3. Any means capable of moving and changing the microlens array 4 by an integral multiple of the pixel pitch p of the light modulation element 3 in a plane perpendicular to the optical axis of the light incident on the light modulation element 3 may be used. The frequency of the field signal supplied to the light modulation element 3 is several tens Hz to several hundreds H
Because of z, an electromagnetic actuator, a linear actuator, a stepping motor, or the like can be used as the actuator 5.

The same effect can be obtained by moving and changing the projection lens 8 instead of vibrating the microlens array 4. In this case, the pixel position on the screen 9 in each image when one screen (frame) is divided into a plurality of images (fields) is different from the case where the light condensing unit is moved and changed. The same effect can be obtained by moving and changing any of the lenses of the projection lens 8, but it is desirable to move and change the lightest lens, and generally it is preferable to move and change the rear lens.

In the present embodiment, the microlens array 4 corresponding to a plurality of pixels is moved and changed. However, a plurality of condensing optical elements each including light emitted from a plurality of pixels adjacent to the light modulating element in each aperture are provided. It is sufficient if there is a light condensing means arranged adjacently and a means for changing the projection area so as to interpolate the projection image discrete by the light condensing means. Optical Technology Contact, Vol. 32, No. 11, p.
8, 1994), and a voltage may be selectively applied in synchronization with a field signal to change the lens formation position.

In this embodiment, the liquid crystal material of the light modulation element 3 is a liquid crystal polymer composite having a transmission scattering mode. However, the present invention is not limited to this.
It is also possible to use N liquid crystal.

Next, a projection type display according to a second embodiment of the present invention will be described with reference to FIGS. The present embodiment is characterized in that a plurality of condensing optical elements each including light emitted from a plurality of pixels adjacent to the light modulation element within each aperture are lenticular lenses corresponding to two pixel rows. The other basic configuration except for the lenticular lens array and the light shielding plate is the same as that of the first embodiment.

FIG. 7 is a perspective view showing the positional relationship between the light modulation element 3, the lenticular lens array, the light shielding plate 6, and the object plane 7 of the projection lens 8 in this embodiment. FIG. 8 shows the positional relationship of the incident light beam on the object plane 7 of the projection lens when one screen is divided into two images. In FIG. 7, reference numeral 42 denotes a lenticular lens corresponding to the two pixel rows, and reference numeral 43 denotes a lenticular lens array including a plurality of lenticular lenses 42. The same components as those in FIG. 1 are denoted by the same reference numerals.

In the present embodiment, the lenticular lens array 43 and the actuators 5b1, 5
The operation of shifting the image by b2 and displaying a high-definition image will be described with reference to FIGS. In the present embodiment, one screen (one frame) is divided into two images (two fields) and displayed.

In the first field, the relative positions of the light modulation element 3, the lenticular lens array 43, and the light shielding plate 6 are at the positions shown in FIG. The lenticular lens array 43 and the light-shielding plate 6 are parallel, and the light-shielding plate 6 is arranged at the focal point of the lenticular lens. The light transmitting regions 61 provided on the light shielding plate 6 are provided in a stripe pattern at a pixel column pitch, and have a width of about 10 μm. 2 adjacent to the light modulation element 3 when the light modulation element 3 is in the ON state.
The outgoing lights 201, 211 and 202, 212 from the rows are condensed like other outgoing lights 201 ', 211' and 202 ', 212' by another lenticular lens having a different central axis, and enter the projection lens 8. At this time, the light incident parallel to the optical axis of the lenticular lens 42 is incident on the projection lens 8 without being blocked by the light-shielding portion 62 of the light-shielding plate 6, so that there is no effective light loss. On the other hand, when the light modulation element 3 is O
The scattered transmitted light in the FF state is shielded by the light shielding portion 62 of the light shielding plate 6 in the same manner as described in the first embodiment with reference to FIG. Can be. The object surface 7 of the projection lens 8 is provided at a position where the light from the light modulation element 3 is converged in half in the horizontal direction. Therefore, the image displayed on the object surface 7 of the projection lens is thinned out in the horizontal direction as shown in FIG. 8A, that is, discretely reduced.

Next, in the second field, the lenticular lens array 43 is moved in the horizontal direction in a plane orthogonal to the optical axis of the light incident on the lenticular lens array 43 by the actuators 5b1 and 5b2 which vibrate in synchronization with the field signal. Then, it is moved to the position shown in FIG. Here, the moving amount of the lenticular lens array 43 from the position of FIG. 7A to the position of FIG. 7B is 50 μm, which is the same as the pixel pitch p of the light modulation element 3. When the light modulating element 3 is in the ON state, the outgoing lights 201, 211 and 202, 212 from two adjacent rows of the light modulating element 3 are respectively emitted by the lenticular lens 42 having the same central axis. The light is converged as 202 ″ and 212 ″ and enters the projection lens 8. At this time, similarly to the first field, the light incident parallel to the optical axis of the lenticular lens 42 is not
, So that there is no effective light loss. When the light modulation element 3 is in the OFF state, scattered light for lowering the contrast is applied to the light shielding portion 6 of the light shielding plate 6 as in the first field.
2 and does not enter the projection lens 8. In the object plane 7 of the projection lens, the light is condensed at the position shown in FIG. 8B, and the gap in the horizontal direction discretely reduced by the lenticular lens array 43 is interpolated in the second field.

According to the first and second fields, 1
As shown in FIG. 8C, the image information of all the frames is formed on the object surface 7 of the projection lens, that is, on the screen 9, and the display with high definition can be realized by using the light modulation element 3 with low definition.

Next, in the first field of the second frame, the lenticular lens array 43 is driven by the actuators 5b1 and 5b2 which vibrate in synchronization with the field signal.
The lenticular lens array 43 is moved in the horizontal direction within a plane orthogonal to the optical axis of the light incident on the, and is moved to the position shown in FIG. Here, from the position of FIG.
The amount of movement of the lenticular lens array 43 up to the position (a) is 50 μm, which is the same as the pixel pitch p of the light modulation element 3. As a result, the light emitted from the light modulation element 3 is focused on the object plane 7 of the projection lens at the position shown in FIG. 8A, and returns to the same position as the first field of the first frame. Less than,
Similar to the first frame, a discretely reduced horizontal gap is interpolated to realize high-definition display.

In the conventional projection display device, it was possible to display on the screen 9 only at a resolution determined by the number of pixels of the light modulation element 3, but according to the projection type display device of the present embodiment, the horizontal resolution is changed by light modulation. The image can be displayed at twice the resolution determined by the number of pixels of the element 3.
Since the lenticular lens array 43 is used as a means for making the image discrete, the light use efficiency is not reduced unlike the means for blocking the light emitted from the light modulation element 3, and the interpolation of the gap is not performed. Is performed by mechanical vibration of the actuator 5, so that an optical system with light absorption such as a polarizing plate or a liquid crystal panel for shifting an image is arranged on the optical path from the light modulation element 3 to the projection lens 8. It is possible to display a bright and high-definition image without lowering the light use efficiency. Further, the light scattered and transmitted by the light modulation element 3 is shielded by the light shielding part 62 of the light shielding plate 6 having a light transmission area corresponding to each light condensing optical element provided on the projection lens side of the optical element. A bright, high-contrast, high-definition image can be displayed.

In the present embodiment, the position where the light emitted from the light modulation element is focused to 後 で after being focused by the lenticular lens 42 is set as the position of the object plane 7 of the projection lens. The position may be a position where the light emitted from the light modulation element before being focused is converged to １ ／. At this time, since the image forming position in each field on the object plane 7 of the projection lens is different, the image forming position on the screen is also different.

In this embodiment, one frame is formed by two fields using a lenticular lens array 43 composed of a plurality of lenticular lenses 42 corresponding to two pixel columns of the light modulation element 3. However, a configuration in which one frame is formed in i-fields using a lenticular lens array 43 including a plurality of lenticular lenses 42 corresponding to i-pixel columns such as a three-pixel column or a four-pixel column may be employed. At this time, the horizontal movement amount Lh of the lenticular lens array 43 with respect to one field signal by the actuator 5 is an integer multiple of the pixel pitch ph, where ph is the horizontal pixel pitch, and ph ≦ Lh ≦ (i−1). ) × ph.

In this embodiment, the actuator 5 uses a laminated piezoelectric element made of a high-strain-rate piezoelectric ceramic material, but the lenticular lens array is synchronized with the frequency of the field signal supplied to the light modulation element 3. Any means capable of moving and changing the lenticular lens array 43 by an integral multiple of the pixel pitch p of the light modulation element 3 in a plane orthogonal to the optical axis of the light incident on the light modulation element 3 may be used. Therefore, since the frequency of the field signal supplied to the light modulation element 3 is several tens Hz to several hundreds Hz, an electromagnetic actuator, a linear actuator,
A stepping motor or the like can be used.

In this embodiment as well, the same effect can be obtained by moving the projection lens 8 instead of moving the lenticular lens array 43, but one screen (frame) is divided into a plurality of images (fields). The pixel position on the screen in each image at the time of the change is different from the case where the condensing unit or the light modulation element 3 is moved and changed. At this time, any of the lens groups constituting the projection lens 8 may be moved and changed. However, since it is desirable to move and change the lightest lens, generally, the rear lens is moved and changed.

In this embodiment, the lenticular lens array 43 is vibrated in the horizontal direction to obtain a high-definition image. However, the shape of the lenticular lens 42 is changed to obtain a high-definition image in the vertical direction. It doesn't matter. Further, it is possible to increase the resolution in the horizontal and vertical directions by using two sets of the lenticular lens array 43 and the vibrating means. At this time, the light shielding plate 6 is provided on the output side of the first lenticular lens array.
As the second light-shielding plate provided on the output side of the second light-shielding plate and the second lenticular lens array, two sets of a lenticular lens array and a light-shielding plate may be provided. Further, it is also possible to provide a light shielding plate only on the output side of the second lenticular lens array on the side of the projection lens 8, or to provide a light shielding portion on the incident surface of the second lenticular lens array. In this case, the number of components can be reduced as compared with the case where two light shielding plates are provided, and more scattered light output from the first lenticular lens array can be shielded.

In contrast to the microlens array used in the first embodiment as the light condensing means, the lenticular lens array used in the present embodiment is advantageous in that the shape of the pixel is used effectively, It is possible to display a bright, high-contrast, high-definition image without lowering the usage efficiency.

[0056]

As described above, according to the present invention, it is possible to increase the definition of a projected display image without increasing the number of pixels of the light modulation element. Further, in the present invention, since a light condensing means such as a microlens array or a lenticular lens array is used as a means for making an image discrete, the use of light such as a means for blocking light emitted from a light modulation element is used. The efficiency is not reduced and the gap is interpolated by the mechanical vibration of the actuator, so that the polarization direction for shifting the polarizing plate or image is on the optical path from the light modulation element to the projection means. It is not necessary to dispose an optical system with light absorption such as a liquid crystal panel for turning the light, and a bright and high-definition image can be displayed without lowering the light use efficiency. Further, since the light scattered and transmitted by the light modulation element is shielded by the light shielding portion of the light shielding plate, a bright and high-definition image with excellent contrast can be displayed.

An actuator such as a piezoelectric element as a vibration means has a vibration amplitude of several μm to several tens μm,
Since it operates at a low vibration frequency of Hz to several hundred Hz,
The switching time of the movement of the light collecting means can be set to 1 millisecond or less. Since the responsiveness is sufficient, the contrast of the image does not decrease.

Further, the optical component used in the present invention has a simple structure such as a microlens array or lenticular lens array formed on a glass substrate, a light shielding plate, and an actuator such as a piezoelectric element, and has a size equivalent to that of a light modulation element. Therefore, the projection type display device of the present invention can be made almost the same size as a conventional display device. Furthermore, even when the number of screen divisions is increased to perform higher-definition image display, the number of parts is increased according to the number of screen divisions as in a conventional display device using a crystal plate and a TN liquid crystal panel. No matter what, the size of the device can be almost the same as a conventional device. Further, the optical components newly used in the present invention can be manufactured with high precision and at low cost, so that the cost of the apparatus hardly changes from the conventional one.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a projection display device according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a microlens array of the projection display device according to the first embodiment of the present invention.

FIG. 3 is a plan view showing a positional relationship between a light modulation element and a convex lens of the projection display device according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view of a plane parallel to the optical axis from the light modulation element of the projection display device according to the first embodiment of the present invention to the object plane of the projection lens, taken along the line AA ′ of FIG. 3;

FIG. 5 is a cross-sectional view of a plane parallel to an optical axis from the light modulation element of the projection display device according to the first embodiment of the present invention to the object plane of the projection lens, taken along the line AA ′ of FIG. 3;

FIG. 6 is a plan view showing a positional relationship of an incident light beam on an object plane of the projection lens when one screen of the projection display according to the first embodiment of the present invention is divided into four images.

FIG. 7 is a perspective view showing a positional relationship among a light modulation element, a lenticular lens array, and an object plane of a projection lens of a projection display according to a second embodiment of the present invention.

FIG. 8 is a plan view showing a positional relationship of an incident light beam on an object plane of a projection lens when one screen of a projection display according to a second embodiment of the present invention is divided into two images.

FIG. 9 is an explanatory diagram showing a configuration of a conventional projection display device.

FIG. 10 is an explanatory diagram showing a configuration of a conventional projection display device.

FIG. 11 is an explanatory diagram showing a configuration of an image projected by a conventional projection display device.

FIG. 12 is an explanatory diagram showing a configuration of a conventional projection display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Collimating conversion lens 3 Light modulation element 4 Micro lens array 5 Actuator 6 Shielding plate 7 Object plane of projection lens 8 Projection lens 9 Screen 41 Micro lens 42 Lenticular lens 43 Lenticular lens array 61 Light transmission area 62 Light shielding part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H04N 5/74 H04N 5/74 A (72) Inventor Keishi Fujimagari 430 Nakaicho, Ashigagami-gun, Kanagawa Prefecture Green Tech Inside Fuji Xerox Co., Ltd.

Claims (6)

[Claims] 1. A projection display device for enlarging and projecting an image displayed by a light modulation element having a plurality of pixels on a screen by a projection means, wherein the projection display apparatus is located on an optical path from the light modulation element to the projection means, As the image on the screen is separated for each of a plurality of pixels, a plurality of light-condensing optical elements including in respective apertures light emitted from a predetermined number of adjacent pixels among the plurality of pixels of the light modulation element. A light condensing means disposed adjacently, a plurality of light transmitting regions for transmitting light emitted from the light condensing means of light incident substantially parallel to the optical axis of the light condensing optical element, and blocking light other than the emitted light A light-shielding means having a light-shielding area; and an image projection area on the screen is changed so as to interpolate an image separated on the screen by the light-collecting means, thereby projecting an image displayed by the light modulation element. Sa That a projection area changing means, a projection display device which is characterized in that the time division display of one frame is composed of a plurality of fields. 2. The projection type display device according to claim 1, wherein said light condensing means sets light emitted from an adjacent (i × j) pixel among a plurality of pixels of said light modulation element within a diameter of each pixel. A projection type display device comprising a micro lens array having a plurality of convex lenses. 3. The projection type display device according to claim 2, wherein the light shielding means is located near a focal plane of the light condensing means,
The projection type display device, wherein the light transmission regions are two-dimensionally arranged at intervals substantially equal to a pixel pitch of the light modulation element. 4. The projection type display device according to claim 1, wherein the light condensing means includes a plurality of pixels included in an adjacent i-line among the plurality of pixels of the light modulation element, each of the plurality of pixels including within its aperture. A projection-type display device comprising a lenticular lens array having a semicircular microlens in cross section. 5. The projection type display device according to claim 4, wherein said light shielding means is located near a focal plane of said light condensing means,
The projection type display device, wherein the light transmission regions are arranged in stripes at intervals substantially equal to a pixel pitch of the light modulation element. 6. The projection display device according to claim 1, wherein the light modulation element is a liquid crystal polymer composite having a transmission scattering mode.