JPH05303071A - Projector - Google Patents

Abstract

PURPOSE:To constitute the liquid crystal projector which can display good images of a small-sized device consisting of a small-sized optical system. CONSTITUTION:The projector for projecting the image displayed on a transmission original plate 2 on a screen is constituted to converge illuminating light by a field lens 1 and to make the converged illuminating light incident on a relay lens 3 for forming the virtual reduced image after passing the light through the transmission original plate 2 and to display the exit light of a projecting lens 4 on the screen by making the exit light of the relay lens 3 for forming the virtual reduced image incident on the projecting lens 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projector for projecting an image on a screen using a transparent original plate such as a liquid crystal panel.

[0002]

2. Description of the Related Art Conventionally, as a projection type color image display device, a so-called liquid crystal projector using a liquid crystal panel has been developed. In this liquid crystal projector, light from a light source such as a xenon lamp is converted into parallel rays by an optical member, and then separated into three colors of red light, green light, and blue light by a dichroic mirror, and separated into respective optical paths. Place the LCD panel. Then, a red image, a green image and a blue image of the projected image are formed on the liquid crystal panel of each optical path, and the light rays of each optical path are converted into red image light,
After forming the green image light and the blue image light, the respective image lights are combined by a dichroic mirror, and the combined light is enlarged and projected on a screen through a projection lens.

Here, FIG. 2 shows an example of a concrete configuration of a liquid crystal projector. In the figure, reference numeral 10 denotes the whole liquid crystal projector, and this projector 10 reflects light from a light source 11 such as a metal halide lamp to a reflecting mirror 12. To form parallel rays, and the parallel rays are incident on the first dichroic mirror 13 as illumination light. Then, the first dichroic mirror 13 causes the green component from the light from the light source 11 to go straight, and causes the other color components to bend 90 °. And
The bent color component is made incident on the second dichroic mirror 14. In the second dichroic mirror 14, the red component is 90 ° from the color component from which the green component has been removed.
Bend it and let the remaining blue component go straight.

Then, the first dichroic mirror 13
The green component separated by is bent by 90 ° by the mirror 17, and then is transmitted through the green liquid crystal panel 19G on which the green component of the color image to be projected is displayed, and the green image light formed by the transmission is converted into the third image light. It is incident on the dichroic mirror 15. Further, the red component separated by the second dichroic mirror 14 is transmitted through the red liquid crystal panel 19G displaying the red component of the color image to be projected, and the red image light formed by the transmission is transmitted to the third dichroic mirror. 1
5. Then, the third dichroic mirror 15 combines the light transmitted through the red liquid crystal panel 19G and the light transmitted through the green liquid crystal panel 19G, and causes the combined light to enter the fourth dichroic mirror 16. Further, the blue component separated by the second dichroic mirror 14 is transmitted through the blue liquid crystal panel 19B where the blue component of the color image to be projected is displayed, and the blue image light formed by the transmission is reflected by the mirror 18 at 90 °. After bending, the 4th
It is incident on the dichroic mirror 16. Then, in the fourth dichroic mirror 16, the combined light of the red component and the green component from the third dichroic mirror 15,
The blue component light transmitted through the blue liquid crystal panel 19B is combined with the projection lens 20 to produce color image light in which the three primary colors are combined.
Incident on.

Then, the image light output from the projection lens 20 reaches a screen (not shown) to display a color image on the screen.

In a liquid crystal projector having a simple structure, a color image is displayed on one liquid crystal panel, and light from a light source is allowed to enter the one liquid crystal panel without being color-separated. Some display the transmitted light of the panel directly on the screen.

With such a configuration, the conventional CRT
Unlike a projector that uses a light source such as an image display unit that also serves as a light source, the liquid crystal panel that is the image display unit and the light source are separate units, so a high-luminance image that corresponds to the brightness of the light source And the resolution is determined by the liquid crystal panel, so that it is possible to project an image with high brightness and high resolution.

[0008]

In the case of this type of liquid crystal projector, in order to increase the resolution of the image displayed on the screen, it is necessary to increase the number of pixels of each liquid crystal panel. In order to realize a projector, it is necessary to use a large liquid crystal panel with many pixels. However, when a large liquid crystal panel is used, there is an inconvenience that a large lens having a large diameter is required as a projection lens for projecting the image light transmitted through the liquid crystal panel, and the size of the optical system of the projector becomes large. At the same time, a lens having a large diameter is very expensive, which increases the manufacturing cost of the projector.

Therefore, when a large liquid crystal panel is used as a transmission original plate, the image circle of the image light transmitted through the liquid crystal panel is reduced by the lens, and the reduced image light is projected on the screen by the projection lens. It is possible.

However, if a lens device for reducing the image circle of the image light is interposed between the liquid crystal panel and the projection lens in this way, the optical path length from the liquid crystal panel to the projection lens becomes long, and the projector device becomes large. There was an inconvenience that

In view of the above points, the present invention has an object to provide a projector of this type with a simple structure and a small size.

[0012]

The present invention is, for example, as shown in FIG. 1, in a projector for projecting an image displayed on a transmission original 2 on a screen, illuminating light is converged by a field lens 1 and the converged light is converged. After passing through the transmission original plate 2, the illumination light is incident on the relay lens 3 for creating a virtual reduced image, and the light emitted from the relay lens 3 for creating a virtual reduced image is input to the projection lens 4, and the projection lens 4 The emitted light is displayed on the screen.

In this case, the transparent original plate 2 is a liquid crystal panel.

[0014]

According to the present invention, an imaginary reduced image is formed by the relay lens before the lens surface, and the optical path length is shortened by the amount that the position of the reduced image is shifted forward as compared with the case of forming the actual reduced image. be able to.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

In this example, a liquid crystal projector for displaying a projected image on a screen is used, and FIG. 1 shows the main part of its optical system. In FIG. 1, reference numeral 1 denotes a field lens, and this field lens 1 is composed of a convex lens, and parallel light from a light source (not shown) enters from one side (right side of FIG. 1). Therefore, in the field lens 1, the incident parallel light is converged light. Then, the liquid crystal panel 2 as a transmission original plate is arranged on the side where the convergent light is emitted from the field lens 1. This liquid crystal panel 2
Uses an image having a diagonal size of 3 inches and displays an image m projected on the screen.

Then, the light transmitted through the liquid crystal panel 2 is made incident on the relay lens 3. The relay lens 3 is a concave lens, and forms a virtual reduced image m ′ in front of the relay lens 3 (on the light source side). This imaginary reduced image m'is, for example, half the size of the image m displayed on the liquid crystal panel 2. Then, the light emitted by the relay lens 3 is made incident on the projection lens 4, and the virtual reduced image m ′ is projected on the screen (not shown) by the projection lens 4, and the enlarged image of the virtual reduced image m ′ is displayed. Display it on the screen.

Here, in order to simplify the explanation,
The field lens 1 and the relay lens 3 are each 1
Although it is composed of a single convex lens and a concave lens, each lens may be composed of a plurality of (group) lenses to substantially function as a convex lens or a concave lens. Further, although only one liquid crystal panel 2 is used as the transmission original plate, a dichroic mirror or the like is arranged in the front and rear optical paths of the liquid crystal panel 2 to provide a three-plate three-primary-color separation / synthesis type liquid crystal projector as shown in FIG. Is also good.

According to the liquid crystal projector of this example constructed as described above, although the liquid crystal panel 2 is a relatively large one having a size of 3 inches,
Since the reduced image m'is formed and the reduced image m'is projected on the screen by the projection lens 4, a small-sized projection lens 4 having a small diameter can be used. For example, by using the liquid crystal panel 2 having a size of 3 inches, it becomes possible to use a 35 mm still camera lens device as a projection lens. In this example, the reduced image m ′ is formed as an imaginary reduced image in front of the lens surface of the relay lens 3, so that the distance from the relay lens 3 to the projection lens 4 can be shortened. Therefore, even if the optical system for forming the reduced image m ′ is used,
The distance from to the projection lens 4 can be made relatively short, and the liquid crystal projector can be made compact.

Although the above-described embodiment is applied to the liquid crystal projector, it is needless to say that the present invention can be applied to other types of projectors.

[0021]

According to the present invention, an imaginary reduced image is formed by the relay lens before the lens surface, and the optical path length is increased by the amount of the position of the reduced image shifted as compared with the case of producing the actual reduced image. The optical system of the projector can be made compact accordingly.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing an example of a conventional liquid crystal projector.

[Explanation of symbols]

 1 Field lens 2 Liquid crystal panel 3 Relay lens 4 Projection lens

Claims (2)

[Claims] 1. A projector for projecting an image displayed on a transmission original onto a screen, wherein illumination light is converged by a field lens, and the converged illumination light is passed through the transmission original to create a virtual reduced image. A projector in which light is made incident on a relay lens, light emitted from the relay lens for creating a virtual reduced image is made incident on a projection lens, and light emitted from the projection lens is displayed on the screen. 2. The projector according to claim 1, wherein the transparent original plate is a liquid crystal panel.