JPH1020242A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device capable of displaying an image at high resolution by performing time division display by a simple constitution without lowering the transmissivity and the contrast of light even by using an optical modulation element whose pixel number is small in the case that the image of one frame is divided into plural fields and are displayed. SOLUTION: A microlens array 4 is arranged on an optical path leading from the optical modulation element 3 to a projection lens 8, and one convex lens is formed corresponding to the four pixels of the optical modulation element 3. Actuators 5 (5a1, 5a2, 5b1, (5b2)) are constituted of the actuators 5a1 and 5a2 vibrating the microlens array 4 in a perpendicular direction and the actuators 5b1 and (5b2) vibrating it in a horizontal direction. The actuator 5 is driven by synchronizing with a field signal supplied to the optical modulation element 3, so that the microlens array 4 is moved or vibrated in the horizontal and perpendicular directions orthogonal with the optical axis of the light made incident on the microlens array 4.

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, projection is performed by shifting the aperture ratio of each pixel of each transmissive liquid crystal panel 12 by about 25% in the horizontal and vertical directions by a half pixel pitch. 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 images at a half pixel pitch 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 high resolution is to be achieved in both the horizontal and vertical directions, two sets of a polarization direction turning means and a quartz plate are required,
Further, the light transmittance is reduced to about 40%. 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 second) is divided into a plurality of fields in the case of time-division display, it takes several to several tens of milliseconds per field. Therefore, when the TN liquid crystal is used, the polarization direction is switched. Time occupies tens of percent of 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 type display device for enlarging and projecting an image displayed by a light modulating element onto a screen by a projecting means, wherein the image is displayed on an optical path from the light modulating element to the projecting means. A light-collecting unit in which a plurality of light-collecting optical elements including emission light from a plurality of pixels adjacent to the light modulation element in respective apertures are arranged adjacently so as to separate an image for each of a plurality of pixels on the screen. By interpolating the image separated on the screen by the light condensing means, by changing the projection area of the image on the screen and projecting the display image by the light modulation element, a plurality of This is achieved by a projection display device characterized in that time-division display in which one frame is composed of fields is performed.

It is another object of the present invention to provide the projection display device, wherein the light condensing means comprises a microlens array comprising a plurality of convex lenses corresponding to i × j pixels of the light modulation element, or an i-line of the light modulation element. A lenticular lens array composed of a plurality of semicircular microlenses having a cross section corresponding to the first or second lenticular lens array composed of a plurality of semicircular microlenses having a cross section corresponding to the i-line of the light modulation element; This is achieved by a projection type display device, which is a second lenticular lens array including a plurality of semi-circular microlenses having a cross section corresponding to the j-th line of the light modulation element orthogonal to the i-th line.

Further, the projection means enlarges and projects the surface on which the area of the light flux from the light modulation element is converged to 1 / (i × j) or 1 / i by the light condensing means on the screen. It is characterized by: Further, the projection area changing means projects a display image by the light modulation element so as to interpolate an image separated on a screen by the light condensing means in synchronization with a field signal supplied to the light modulation element. It is characterized by doing.

Further, the present invention is characterized in that the amount of change in the movement of the vibration of the light condensing means synchronized with the field signal supplied to the light modulation element is an integral multiple of the pixel pitch of the light modulation element. Further, the projection area changing means is characterized in that the condensing means or the projection means is mechanically vibrated in a plane orthogonal to an incident optical axis by an electromagnetic actuator, a linear actuator, a piezoelectric actuator, a stepping motor, or the like. I have.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection type 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 including emission light from a plurality of pixels adjacent to the light modulation element in respective apertures are arranged adjacently, and an image separated on a screen by the light-collecting means is interpolated. By a projection area changing means for projecting a display image by the light 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. Further, in the projection display device according to the present embodiment, since there is no optical system with light absorption on the optical path from the light modulation element to the screen, a bright image can be obtained even if the number of pixels is increased and the definition is increased.

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 apparatus according to the present embodiment, FIG. 2 is a perspective view of a microlens array used in the present embodiment, and FIGS. 3 and 4 are light modulations according to the present embodiment. FIG. 3 is an explanatory view showing a positional relationship between the element and the convex lens, FIG. 3 is a plan view showing a positional relationship between the light modulating element and the convex lens, and FIG. 4 is a plane parallel to the optical axis from the light modulating element to the projection lens object plane. FIG. 3B is a cross-sectional view of FIG. 3A-A ′. FIG. 5 shows the positional relationship of the incident light beam on the projection lens object plane 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, 8 is a projection lens, 7 is an object surface of the projection lens 8, and 9 is 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 actuators 5a1 and 5a2 that vibrate the microlens array 4 in the vertical direction (vertical direction on the paper) and actuators 5b1 and 5b2 that vibrate in the horizontal direction (normal direction on the paper).
(Not shown). 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. The projection lens 8 has a function of enlarging and projecting the object plane 7 of the projection lens 8 on a screen 9.

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. In this method, certain kinds of ions are diffused into a transparent glass substrate to form layers having different refractive indices and are used as a lens effect. The microlens array 4 is designed to collect as much as possible light beams emitted from four pixels.
It is composed of a number of convex lenses formed at a pitch of 00 μm. 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 operation of shifting an image by the microlens array 4 and the actuator 5 and displaying a high-definition image according to the present embodiment will be described with reference to FIGS. In the present embodiment, one screen (frame) is divided into four images (fields) and displayed. Note that the actual planar shape of each microlens is 4 as shown in FIG.
Each pixel has a rectangular shape including the entirety of the pixels within its aperture, but in the plan views of FIGS. 3 and 5, each microlens is indicated by a solid or broken circle in order to clarify the position of each microlens.

Now, in the first field of the first frame, the relative positions of the pixels of the light modulation element 3 and the microlenses are as shown in FIG. For example, the central axis of the micro lens 4a is a pixel of the light modulation element 3,
, And outgoing light from the pixels,... Are collected by one microlens 4a.
As shown in FIG. 4, the outgoing lights 101 and 102 from the pixels of the light modulation element 3 become outgoing lights 101 ′ and 102 ′ collected by the microlens array 4 and enter the projection lens 8. At this time, the object surface 7 of the projection lens 8 is located 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 8 is shown in FIG.
As shown in FIG. 5, the state is thinned out in the horizontal / vertical directions, that 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 center axis of the micro lens 4a moves to the position of the intersection of the pixels 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. 4, the outgoing lights 101 and 102 from the pixels of the light modulation element 3 are collected by the microlens array 4 to become outgoing lights 101 ″ and 102 ″, and enter the projection lens 8. Object plane 7 of projection lens 8
In FIG. 5B, light is condensed at the position shown in FIG. 5B, and the vertical gap portion discretely reduced in the first field by the microlens array 4 is interpolated in the second field.

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 microlens 4a is the position of the intersection of the pixels of the light modulation element 3, that is, FIG.
Move to position (c). 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 converged on the object plane 7 of the projection lens at the position shown in FIG. 5C, and is discretely reduced in the second field by the microlens array 4. This means that the horizontal gap 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 microlens 4a is the position of the intersection of the pixels 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 by the third field by the microlens array 4, that is, the horizontal gap discretely reduced by the first field is interpolated by the fourth field. .

By the above-mentioned first, second, third and fourth fields, 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 4a
Moves to the position of the intersection of the pixels 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 converged on the object plane 7 of the projection lens 8 at the position shown in FIG. 5A 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.

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

In the conventional projection type 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 reduced by 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.

In this embodiment, the light modulating element 3
Although one frame is formed by four fields using the microlens array 4 including a plurality of microlenses corresponding to pixels (2 × 2 pixels), 9 pixels (3 × 3 pixels) and 16 pixels are formed. (4 × 4 pixels), 6 pixels (2 × 3 pixels), 12 pixels (3 × 4 pixels), etc.
j) Using a microlens array 4 composed of a plurality of microlenses corresponding to pixels, 1
It may be configured to form a frame. At this time, the amount of movement Lh, L in the horizontal / vertical direction with respect to one field signal of the microlens array 4 by the actuator 5
v is the number of pixels corresponding to the horizontal direction of the microlens corresponding to a plurality of pixels is i, the number of pixels corresponding to the vertical direction 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, which is an integral multiple of the pixel pitch ph, 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 the light emitted from a plurality of pixels adjacent to the light modulation 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.

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 is the same as that of the first embodiment.

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

Hereinafter, in this embodiment, the lenticular lens array 6 and the actuators 5b1, 5b
The operation of shifting the image by 2 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 position between the light modulation element 3 and the lenticular lens array 6 is at the position shown in FIG. 6A, and the emitted lights 201, 211 and 202 from two adjacent rows of the light modulation element 3 are provided. , 212 are emitted light 201 ′, 21 by lenticular lenses having the same central axis.
The light is condensed like 1 ′ and 202 ′, 212 ′ and enters the projection lens 8. 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 plane 7 of the projection lens is thinned out in the horizontal direction as shown in FIG. 7A, that is, discretely reduced.

Next, in the second field, the lenticular lens array 6 is moved in the horizontal direction in a plane orthogonal to the optical axis of the light incident on the lenticular lens array 6 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 6 from the position of FIG. 6A to the position of FIG. 6B is 50 μm, which is the same as the pixel pitch p of the light modulation element 3. At this time, outgoing lights 201, 211 and 2 from two adjacent rows of the light modulation element 3
02 and 212 are emitted lights 201 ″, 211 ″ and 20 by different lenticular lenses having different central axes, respectively.
The light is condensed like 2 ″ and 212 ″ and enters the projection lens 8. In the object plane 7 of the projection lens, the light is condensed at the position shown in FIG. 7B, and the gap in the horizontal direction discretely reduced by the lenticular lens array 6 is interpolated in the second field.

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

Next, in the first field of the second frame, the actuators 5b1 and 5b2 which vibrate in synchronization with the field signal are lenticular in the horizontal direction in a plane orthogonal to the optical axis of the light incident on the lenticular lens array 6. The lens array 6 is moved to the position shown in FIG. Here, the moving amount of the lenticular lens array 6 from the position of FIG. 6B to the position of FIG. 6A 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 condensed on the object plane 7 of the projection lens at the position shown in FIG. 7A, and returns to the same position as the first field of the first frame. Hereinafter, similarly to the first frame, the gaps in the horizontal direction that are discretely reduced are interpolated to realize a display with high definition.

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 this 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 6 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.

In the present embodiment, one frame is formed by two fields using a lenticular lens array 6 composed of a plurality of lenticular lenses corresponding to two pixel rows of the light modulation element 3. A configuration in which one frame is formed in the i-field using a lenticular lens array 6 including a plurality of lenticular lenses corresponding to the i-pixel row such as a pixel row or a 4-pixel row. At this time, the horizontal movement amount Lh of the lenticular lens array 6 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 a field signal supplied to the light modulation element 3. Any means capable of moving and changing the lenticular lens array 6 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 as the actuator 5.

In this embodiment as well, the same effect can be obtained by moving the projection lens 8 instead of moving the lenticular lens array 6, 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 6 is vibrated in the horizontal direction to obtain a high-definition image. However, the shape of the lenticular lens 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 6 and the vibrating means.

FIG. 8 is a perspective view showing the positional relationship between the light modulation element 3, the lenticular lens array, and the object plane 7 of the projection lens when two sets of the lenticular lens array 6 and the vibrating means are used. In FIG. 8, reference numeral 6a denotes a first lenticular lens array that focuses light in the horizontal direction, and 6b denotes a second lenticular lens array that focuses light in the vertical direction. Here, a lenticular lens array having lenticular lenses respectively corresponding to two pixel columns is used. First and second lenticular lens arrays 6a,
Reference numeral 6b has a focus on the object plane 7 of the projection lens so as to converge the light emitted from the light modulation element 3 to 水平 each in the horizontal and vertical directions. As a result, on the object plane 7 of the projection lens, as in the first embodiment, a state in which each pixel is thinned in the horizontal and vertical directions in units of four adjacent pixels, that is, a state in which the pixel is discretely reduced is obtained. . The first and second lenticular lens arrays 6a and 6b are synchronized with a field signal, and the actuators 5b1 and 5b2 are arranged on surfaces orthogonal to the optical axis of light incident on the first and second lenticular lens arrays 6a and 6b, respectively. , And 5
By moving in the horizontal / vertical directions by a1, 5a2, the same effect as in the first embodiment can be obtained.

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 increases the number of components, but uses the pixel shape effectively. Advantageously, a high-definition image can be displayed without lowering the light use efficiency.

[0052]

As described above, according to the present invention, on the optical path from the light modulating element to the projection means, the light emitted from a plurality of pixels adjacent to the light modulating element for separating an image into a plurality of pixels on a screen. A light-collecting means in which a plurality of light-collecting optical elements included in respective apertures are arranged adjacently; and a projection area changing means for projecting a display image by a light modulation element so as to interpolate an image separated on a screen by the light-collecting means. As a result, since the image is made discrete and time division display is performed so as to interpolate the gap, it is possible to increase the definition of the 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 means for making an image discrete, the light emitted from the light modulation element is blocked as in the means for blocking light emitted from the light modulation element. The use of light is not reduced, and the gaps are interpolated by mechanical vibration of the actuator, so that a polarizing plate or image is shifted on the optical path from the light modulator to the projection unit. It is not necessary to arrange an optical system with light absorption such as a liquid crystal panel for rotating the polarization direction of the light, and a bright and high-definition image can be displayed without lowering the light use efficiency.

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 and an actuator such as a piezoelectric element, and has the same size (number) as that of a light modulation element. cm), the projection display device of the present invention can be made approximately 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 an optical axis from a light modulation element to a projection lens object plane of the projection display device according to the first embodiment of the present invention, taken along the line AA ′ of FIG. 3;

FIG. 5 is a plan view showing a positional relationship of an incident light beam on a projection lens object plane when one screen of the projection display device according to the first embodiment of the present invention is divided into four images.

FIG. 6 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 device according to a second embodiment of the present invention.

FIG. 7 is a plan view showing a positional relationship of an incident light beam on a projection lens object plane when one screen of a projection display device according to a second embodiment of the present invention is divided into two images.

FIG. 8 is a perspective view showing a positional relationship among a light modulation element, a first lenticular lens array, a second 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.

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 Lenticular lens array 7 Object plane of projection lens 8 Projection lens 9 Screen

Continued on the front page (72) Inventor Keishi Fujimaga

Claims (15)

[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 arranged adjacently, and changing an image projection area on the screen to interpolate an image separated on the screen by the light condensing means to project an image displayed by the light modulation element. A projection display device comprising: a projection area changing unit; and performing time-division display in which 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 1, wherein said light condensing means includes a plurality of light beams emitted from pixels on an adjacent i-line among a plurality of pixels of said light modulation element within respective apertures. A projection-type display device comprising a lenticular lens array having a semicircular microlens in cross section. 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. Having a semicircular microlens in cross section
And a second lenticular lens array having a plurality of semi-circular microlenses with cross-sections including light emitted from pixels on the j-th line orthogonal to the i-line within respective apertures. A projection type display device characterized by the above-mentioned. 5. The projection type display device according to claim 2, wherein said projection means adjusts a surface on which the area of a light beam from said light modulation element is converged to 1 / (i × j) by said microlens array. A projection display device, wherein the projection display is enlarged and projected on the screen. 6. The projection type display device according to claim 3, wherein said projection means sets, on the screen, a surface on which an area of a light flux from the light modulation element is converged to 1 / i by the lenticular lens array. A projection display device characterized by performing enlarged projection. 7. The projection type display device according to claim 4, wherein the projection unit is configured such that an area of a light beam from the light modulation element is 1 / (1) by the first lenticular lens array and the second lenticular lens array. A projection display device, wherein a surface converged at (i × j) is enlarged and projected on the screen. 8. The projection type display device according to claim 1, wherein said projection area changing means is supplied to said light modulation element so as to interpolate an image separated on said screen by said light condensing means. A projection display device, wherein an image displayed on the screen is projected by changing an image projection area on the screen in synchronization with a field signal. 9. The projection type display device according to claim 1, wherein said projection area changing means vibrates said light collecting means in a plane orthogonal to an optical axis of light incident on said light collecting means. Projection type display device. 10. The projection type display device according to claim 9, wherein the amount of change in the movement of the vibration of the light condensing means by the projection area changing means synchronized with a field signal supplied to the light modulation element is the light modulation. A projection type display device characterized by being an integral multiple of a pixel pitch of an element. 11. The projection display apparatus according to claim 1, wherein said projection area changing means vibrates said projection means in a plane orthogonal to an optical axis of said projection means. . 12. The projection type display device according to claim 2, wherein said projection area changing means vibrates said micro lens array in a plane orthogonal to an optical axis of light incident on said micro lens array. Projection type display device. 13. The projection type display device according to claim 3, wherein said projection area changing means vibrates said lenticular lens array in a plane orthogonal to an optical axis of light incident on said lenticular lens array. Projection type display device. 14. The projection type display device according to claim 4, wherein said projection area changing means is configured to set the first lenticular lens array in a plane orthogonal to an optical axis of light incident on the first lenticular lens array. And the second lenticular lens array are vibrated in directions orthogonal to each other. 15. The projection type display device according to claim 9, wherein said projection area changing means mechanically vibrates said light condensing means or said projection means. Display device.