JPH06258596A - Projection type display device - Google Patents

Abstract

PURPOSE:To provide the new projection type display device which is shortened in projection distance, increased in enlargement rate, and improved in lens performance. CONSTITUTION:The projection type display device projects light containing color components of the primary colors from a light source 1, separates the light into the respective components of the primary colors and illuminates corresponding transmission type display bodies 5a, 5b, and 5c with the color-separated light components, and putting together and projecting the respective color light components passed through the respective transmission type display bodies on a screen to display a color image on the screen, and, its projection lens consists of a common front group 7 which is arranged on the screen side and plural rear groups 6a, 6b, and 6c combined with the front group and a color light multiplexing means 8 is arranged between the rear groups 6a, 6b, and 6c and front group 7 so that the light components passed through the rear groups are put together and made incident on the front group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display device. INDUSTRIAL APPLICABILITY The present invention can be widely used for a color projection type display device using a transmissive display body such as a front type liquid crystal projector or a so-called rear type liquid crystal projection television.

[0002]

2. Description of the Related Art A light source emits light containing color components of three primary colors, the light is color-separated into respective color components of the three primary colors, and the corresponding transmissive display is illuminated by each color-separated color component light. However, a projection display device that displays color images on a screen by combining the color component lights that have passed through the respective transmissive displays and projecting them on the screen has been widely known as a liquid crystal projector or the like. . FIGS. 6 and 7 show a typical projection type display device 2 which has been conventionally known.
Here is an example:

In FIG. 6, the light source 1 emits light containing color components of three primary colors. The radiated light has its infrared component removed by the infrared filter 2 and enters the dichroic mirror 3a. The dichroic mirror 3a transmits green component light and blue component light and reflects red component light. The green component light and the blue component light transmitted through the dichroic mirror 3a enter the dichroic mirror 3b,
The blue component light is transmitted through the dichroic mirror 3b, and the green component light is reflected by the dichroic mirror 3b. In this way, the light from the light source 1 is separated into red component light, green component light, and blue component light by the dichroic mirrors 3a and 3b.

The red component light is reflected by the reflection mirror 4b, then passes through the transmissive display 5a for the red component, and enters the color light combining means 8. The green component light passes through the transmissive display body 5b for the green component and enters the color light combining means 8.
The blue component light is sequentially reflected by the reflecting mirrors 4a and 4c, then passes through the transmissive display body 5c for the blue component, and enters the color light combining means 8.

The color light combining means 8 is a cross type dichroic prism, which reflects red component light and blue component light and transmits green component light. Therefore, the color light combining means 8
The red, green, and blue color component lights that are incident on different directions from each other are combined with each other and enter the projection lens 12.

The projection lens 12 projects the image information displayed on the transmissive display bodies 5a, 5b and 5c on a screen (not shown) with red, green and blue component lights, respectively, and the above-mentioned images on the screen. A color image having information as the three primary color components is synthetically formed.

Also in the projection type display apparatus of FIG. 7, the light source 1
The infrared component is removed by the infrared filter 2, and the light from is separated into red, green, and blue component light by the dichroic mirrors 3a and 3b.

The red component light is reflected by the reflection mirror 4b and then transmitted through the transmissive display body 5a for the red component,
It is incident on the color light combining means 10a. The green component light passes through the transmissive display body 5b for the green component, and the two-color light combining means 10a
Incident on. The two-color light combining means 10a is a dichroic mirror that transmits red component light and reflects green component light. Therefore, the red component light and the blue component light are combined by the two-color light combining means 10a and enter the color light combining means 10b.

The blue component light is transmitted through the transmissive display 5c for the blue component and then reflected by the reflection mirror 4a,
It enters the color light combining means 10b.

The color light combining means 10b is a dichroic mirror, which reflects red component light and green component light and transmits blue component light. Therefore, the red, green, and blue color component lights are combined with each other by the color light combining means 10b and enter the projection lens 12.

The projection lens 12 projects the image information displayed on the transmissive display bodies 5a, 5b, 5c on a screen (not shown) with red, green, and blue component lights, respectively, and the above-mentioned each on the screen. A color image having image information as the three primary color components is synthetically formed.

In recent years, such a projection type display device is required to shorten the projection distance and increase the enlargement ratio. Further, in order to improve the image quality of the display image, it is required to improve the performance of the projection lens.

In the conventional projection display device, the light transmitted through the transmissive display for each color component and combined by the color light combining means enters the projection lens. Therefore, the projection lens is a space for disposing the color light combining means. Therefore, a large back focus (the distance from the surface of the projection lens closest to the transmissive display body to the transmissive display body) is required (especially in the case of the optical configuration of FIG.
This tendency is remarkable), this "big back focus"
The restriction of requiring a lens makes it extremely difficult to shorten the projection distance, increase the enlargement ratio, and improve the lens performance.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is a novel projection type that can easily shorten the projection distance, increase the enlargement ratio, and improve the lens performance. The purpose is to provide a display device.

[0015]

The projection type display device of the present invention is described as follows: "A light source emits light containing color components of three primary colors, and this light is color-separated into color components of the three primary colors. A color image is displayed on the screen by illuminating the corresponding transmissive display (such as a liquid crystal light valve) with each of the component lights, synthesizing each color component light transmitted through each transmissive display, and projecting it on the screen. Device,
It is characterized by the following points.

That is, the "projection lens" is composed of a "common front group" arranged on the screen side and a "plurality of rear groups" combined with the front group. Then, so that the light passing through the plurality of rear groups is combined and incident on the front group,
A “color light combining means” is provided between the plurality of rear groups and the front group.

The number of lens groups provided on the rear group, that is, on the side of the light source is three, and the "color light combining means" provided between these three rear groups and the front group have three primary colors. It is possible to combine the separate color component lights of the above (claim 2). Further, the number of lens groups forming the rear group is two, and the light passing through one rear group is composed of two color component lights of the three primary colors previously combined by the “two-color light combining means”. May be used (claim 3).

In the projection type display device according to claim 1, 2 or 3, the color light combining means can be constituted by a dichroic mirror or a dichroic prism (claim 4), and the two-color light combining means in the device according to claim 3 is also a dichroic mirror. Alternatively, it can be composed of a dichroic prism.

[0019]

As described above, in the present invention, since the "color light combining means" is provided between the common front group and the plurality of rear groups, the back focus of the projection lens can be shortened.

[0020]

[Examples] Three examples will be given below. In order to avoid complication, the same reference numerals as those in FIGS. 6 and 7 described above are used in FIGS.

FIG. 1 schematically shows the optical arrangement of an embodiment of the invention described in claims 1, 2, and 4. Light including the color components of the three primary colors emitted from the light source 1 has its infrared component removed by the infrared filter 2, and is separated into red component light, green component light, and blue component light by the dichroic mirrors 3a and 3b. .

The red component light is reflected by the reflection mirror 4b,
The light passes through the transmissive display 5a for the red component and enters the color light combining means 8 through the rear group 6a. The green component light passes through the transmissive display 5b for the green component and enters the color light combining means 8 via the rear group 6b. The blue component light is reflected by the reflection mirror 4a,
4c, which is sequentially reflected, and is a transmissive display body 5 for the blue component.
After passing through c, it enters the color light combining means 8 through the rear group 6c.

The color light combining means 8 is a cross type dichroic prism, which reflects red component light and blue component light,
Transmits green component light. Therefore, the red, green, and blue color component lights that enter the color light combining means 8 from different directions are combined with each other and enter the front group 7.

The projection lens has a front group 7 in common and three rear groups 6a, 6b, 6 which are independently combined with the front group.
It is composed of c. The rear group 6a and the front group 7 constitute a projection lens for red component light, and the image information displayed on the transmissive display body 5a is enlarged and projected on a screen (not shown) by the red light. The rear group 6b and the front group 7 constitute a projection lens for green component light, and the image information displayed on the transmissive display body 5b is enlarged and projected on a screen (not shown) by the green light. The rear group 6c and the front group 7 constitute a projection lens for blue component light, and the transmission type display body 5c.
The image information displayed on the screen is enlarged and projected on a screen (not shown) by blue light. Therefore, a color image having the above-mentioned image information as the three primary color components is synthetically formed on the screen.

FIG. 2 shows a modification of the embodiment shown in FIG. The difference from the embodiment of FIG. 1 is that the color light combining means is “a combination of dichroic mirrors 9a and 9b in a cross type”. The dichroic mirror 9a transmits red light and transmits green light and blue light. The dichroic mirror 9b transmits red light and green light and reflects blue light. In this way, the respective color component lights incident on the front group 7 are combined.

FIG. 3 schematically shows an optical arrangement according to an embodiment of the invention described in claims 1, 3, 4, and 5. The light from the light source 1 has its infrared component removed by an infrared filter 2, and is separated into red, green, and blue color component lights by the dichroic mirrors 3a and 3b.

The red component light is reflected by the reflection mirror 4b, transmitted through the transmissive display 5a for red component, and enters the two-color light combining means 10. The green component light passes through the transmissive display body 5b for the green component and enters the two-color light combining means 10. The two-color light combining means 10 transmits the red component light and reflects the green component light by the dichroic mirror. Therefore, the red component light and the blue component light are combined by the two-color light combining means 10 and enter the color light combining means 11 via the rear group 6A.

The blue component light is transmitted through the transmissive display 5c for the blue component and then reflected by the reflection mirror 4a, and the rear group 6
It is incident on the color light combining means 11 via B.

The color light combining means 11 is a dichroic prism, which reflects red light and green light and transmits blue light. Therefore, the red, green, and blue color component lights are combined with each other by the color light combining means 11 and are incident on the common front group 7A.

The projection lens has a front group 7A in common and is composed of two rear groups 6A and 6B which are independently combined with the front group. The rear group 6A and the front group 7A constitute a projection lens for the red component light and the green component light, and the image information displayed on the transmissive display bodies 5a, 5b is enlarged by a red / green light on a screen (not shown). To project. The rear group 6B and the front group 7A configure a projection lens for blue component light, and project image information displayed on the transmissive display body 5c by blue light on a screen (not shown) in an enlarged manner.
Therefore, a color image having the above-mentioned image information as the three primary color components is synthetically formed on the screen.

FIG. 4 shows the front group 7A and the rear group 6 shown in FIG.
The front lens group 7A and the rear lens groups 6A and 6B each have a five-lens structure, showing an example of a specific lens structure of the rear lens group 6A.
The lenses of A and 6B (they have the same lens configuration) on the side of the color light synthesizing means 11 are cemented lenses of a concave lens and a convex plano lens.

FIG. 5 shows a modification of the embodiment shown in FIG. The difference from the embodiment of FIG. 3 is that the color light combining means is a dichroic mirror 10B. Dichroic mirror 1
0B transmits blue light and transmits red light and green light. In this way, the respective color component lights incident on the front group 7A are combined.

The optical arrangements of the embodiments of FIGS. 1 and 2 are compared with the optical arrangement of the conventional example of FIG. 6, and the optical arrangements of the embodiments of FIGS. 3 and 5 are compared with the optical arrangement of the conventional example of FIG. As will be immediately apparent, by disposing the color synthesizing means between the front group and the rear group, the distance from the lens surface on the transmissive display body side of the rear group to the transmissive display body, that is, the projection lens It is clear that the back focus is extremely shorter than that of the conventional one. The effect of shortening the back focus is particularly remarkable in the embodiments of FIGS. 3 and 5, and can be shortened to 1/2 or less of the conventional one.

[0034]

As described above, according to the present invention, a novel projection display device can be provided. Since this device is configured as described above, the back focus of the projection lens can be set short, and restrictions on the back focus are alleviated to increase the enlargement magnification and performance of the projection lens, shorten the projection distance, etc. Is easily realized, and a projection type display device with good performance can be realized.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an optical arrangement according to an embodiment of the invention described in claims 1, 2 and 4.

FIG. 2 is a diagram schematically showing an optical arrangement of a modified example of the invention described in claims 1, 2 and 4.

FIG. 3 is a diagram schematically showing an optical arrangement of an embodiment of the invention according to claims 1, 3, 4, and 5.

FIG. 4 is a diagram showing a specific lens configuration of a front group and a rear group in the embodiment of FIG.

FIG. 5 is a diagram schematically showing an optical arrangement of a modified example of the invention described in claims 1, 3, 4, and 5.

FIG. 6 is a diagram schematically showing an example of an optical arrangement of a conventional device.

FIG. 7 is a diagram schematically showing another example of the optical arrangement of the conventional device.

[Explanation of symbols]

 1 light source 3a, 3b dichroic mirror 4a, 4b, 4c mirror 5a, 5b, 5c transmissive display 6a, 6b, 6c rear group 7 front group 8 color light combining means

Claims (5)

[Claims] 1. A light source emits light containing color components of three primary colors, the light is color-separated into respective color components of the three primary colors, and a corresponding transmissive display is illuminated by each color-separated color component light. In a projection display device that synthesizes the color component lights that have passed through the transmissive displays and projects them on the screen to display a color image on the screen, a projection lens is commonly used on the screen side. A front group and a plurality of rear groups combined with the front group, and between the plurality of rear groups and the front group such that light passing through the plurality of rear groups is combined and incident on the front group. A projection display device characterized in that a color light synthesizing means is provided in the. 2. The projection type display device according to claim 1, wherein the number of rear groups in the projection lens is three, and the color light combining means provided between the rear group and the front group are three primary colors. 2. A projection type display device characterized in that the separate color component lights of the above are combined. 3. The projection type display device according to claim 1, wherein the number of rear groups in the projection lens is two, and light passing through one of the rear groups becomes two of the three primary colors by the two-color light combining means. A projection type display device characterized by being composed of two color component lights. 4. The projection type display device according to claim 1, 2 or 3, wherein the color light combining means is a dichroic mirror or a dichroic prism. 5. The projection type display device according to claim 3, wherein the two-color light combining means is a dichroic mirror or a dichroic prism.