JPH05119401A - Projection type display device - Google Patents

Abstract

PURPOSE:To provide the display device which can be diminished in the depth of the device and the height thereof and can dispose a display screen without deviating vertically with a housing. CONSTITUTION:This projection type display device consists of an image forming means 5 for forming the luminous flux of an image, a projecting lens 6 for macroprojecting the luminous flux formed by this image forming means 5, a transmission type screen 2 for imaging the luminous flux projected by the projecting lens 6, and plural mirrors which exist between the projecting lens 6 and the transmission type screen 2 and bend the luminous flux. These plural mirrors consist of a 1st group of the mirrors consisting of at least one piece of the mirrors 11 which split the luminous flux emitted from the projecting lens 6 to two luminous fluxes and a 2nd group of the mirrors 21 to 28 which bend the plural split luminous fluxes by respectively reflecting these luminous fluxes and synthesize the luminous fluxes so as to form the prescribed image on the screen 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear projection type display device capable of displaying a large screen in a bright environment. In recent years, there is an increasing demand for a display for enjoying powerful images for consumer use, and a display for industrial use such as a presentation terminal or a CAD terminal requiring a large display capacity. As a display device that can satisfy the large screen and high-definition full-color display required for these displays at present, it can be said that only a CRT display is a direct-view type, but the CRT display is a large device in terms of weight and thickness. Has restrictions. Therefore, recently, a rear projection type display device capable of displaying a large screen and high definition has been attracting attention.

[0002]

2. Description of the Related Art Projection type display devices include a front projection type and a rear projection type. The front projection type has the advantage of increasing the screen size, but it has a limited environment in which it is dark and needs a large area. Therefore, the rear projection type is suitable for information processing that needs to be used in a narrow space in a bright place such as an office. However, with the current rear projection type optical technology, a rear projection type display device of a size capable of using a display of 20 to 30 inches on a desk has not been made, and its realization is desired.

Further, recently, researches using a liquid crystal panel as a light valve for image formation have been advanced. An example of a rear projection type display device using a liquid crystal panel is shown in FIG. In FIG. 9, a screen 2 is arranged in front of a housing 1 of the apparatus, and a light source 3, a condenser lens 4, a liquid crystal panel 5, and a projection lens 6 are arranged inside the housing 1. The liquid crystal panel 5 optically modulates the light from the light source 3 for each minute pixel to form a light flux of an image. The light flux thus formed spreads through the projection lens 6 and is projected on the back surface of the screen 2. Since the screen 2 is light transmissive,
A viewer in front of the screen 2 can see the image on the screen 2.

In such a rear projection type display device, the projection lens 6 and the screen 2 are used to increase the magnification of the image.
There is a problem in that the length between the two is long, and therefore the depth of the housing 1 of the device is long. In order to solve this, a rear projection display device as shown in FIG. 10 has been developed. In FIG. 10, the screen 2, the light source 3,
A condenser lens 4, a liquid crystal panel 5, and a projection lens 6 are arranged, and a plurality of mirrors 7 and 8 are arranged between the projection lens 6 and the screen 2. These mirrors 7 and 8 are for projecting the light beam emitted from the projection lens 6 onto the screen 2 while bending it, and the size and the optical path length of the light beam are the same as those shown in FIG. In this case, the depth of the housing 1 can be made shorter than that of FIG. 9, and a more compact rear projection display device can be provided.

[0005]

However, in the configuration of FIG. 10, it is necessary to dispose the liquid crystal panel 5 and the projection lens 6 obliquely with respect to the screen 2, and conventionally, the screen 2 is located above the housing 1. The liquid crystal panel 5 and the projection lens 6 are arranged below the housing 1. Therefore, there is a problem that the height of the housing 1 becomes large. Further, when viewed from the front of the housing 1, the ratio of the non-display portion to the display portion (screen 2) becomes large, and the screen 2
Since the position of ∘ does not depend on either the upper side or the lower side of the housing 1, the design of the device is restricted.

An object of the present invention is to provide a projection type display device in which the depth and height of the device can be reduced, and the display screen can be arranged without bending up and down with respect to the housing.

[0007]

As shown in FIGS. 1 and 5, a projection type display device according to the present invention includes an image forming means 5 for forming an image light beam, and a light beam formed by the image forming means. A projection lens 6 for enlarging and projecting a light beam, a transmissive screen 2 for forming an image of the light beam projected by the projection lens 6, and a plurality of bending light beams between the projection lens 6 and the transmissive screen 2. A projection type display device comprising a plurality of mirrors,
A first group of mirrors 11, which is composed of at least one mirror that splits a light beam emitted from the projection lens into a plurality of light beams,
12, 12a and a second group of mirrors 21 to 21 that combine the divided plural light fluxes so that they are bent and reflected to form a predetermined image on the screen 2.
And 28.

In a preferred embodiment, as shown in FIG. 1, the projection lens 6 and the first group of mirrors 11 are arranged on a vertical line standing substantially in the center of the screen 2, and the first group of mirrors 11 and Each of the second group of mirrors 21 to 28 is composed of a plurality of mirrors arranged in line symmetry with respect to a line passing through the optical axis of the projection lens. In another preferred embodiment, as shown in FIG. 5, the first group of mirrors 1
2, 12a receives a part of the light beam emitted from the projection lens 6 and reflects it, and passes the light beam emitted from the projection lens 6 without passing through the side thereof, thereby splitting into at least two light beams. It consists of one mirror, the second
The mirrors 21 to 23 of the group are configured so as to be directed toward the screen 2 so that the optical paths of the two divided light beams have the same length.

[0009]

In the above structure, the luminous flux emitted from the projection lens 6 is divided into a plurality of luminous fluxes, so that the size of the mirrors 21 to 28 that bend the divided luminous fluxes after that is not divided. It can be made smaller than the size, and the depth of the device can be made small and the height can be made small by repeating the bending of the light beam by a small mirror. In the above configuration,
It becomes possible to appropriately arrange an optical system such as a projection lens between the mirrors or on the back side of the mirrors or the like, and it is possible to arrange the position of the screen occupying on the housing without vertically bending.

[0010]

FIG. 1 is a diagram for explaining the principle of the present invention, and FIG. 2 is a diagram showing a first embodiment of a rear projection type display device of the present invention. The arrangement of the mirrors is the same in FIGS. 1 and 2. In FIG. 2, a screen 2 is arranged on the front surface of a housing 1 of the apparatus, and inside the housing 1, a light source 3, a condenser lens 4, a liquid crystal panel 5, and a projection lens 6 are arranged.
The liquid crystal panel 5 optically modulates the light from the light source 3 for each minute pixel to form a light flux of an image. The condenser lens 4 is for allowing the light flux passing through the liquid crystal panel 5 to be condensed by the projection lens 6, and the projection lens 6 is for spreading the light flux and enlarging and projecting the image on the screen 2. The condenser lens 4, the liquid crystal panel 5, and the projection lens 6 are arranged on a vertical line that stands in the center of the screen 2.

In order to project the light flux emitted from the projection lens 6 onto the screen 2 while bending it, the projection lens 6
A plurality of mirrors 11, 21 to 28 between the screen and the screen 2.
Are placed. Of these, the mirror 11 is arranged coaxially with the projection lens 6, and splits the light flux emitted from the projection lens 6 into two light fluxes. Although the mirror 11 is a single mirror having a roof-shaped cross section in this embodiment, it may be formed of a plurality of mirrors. Therefore, the mirror 11 can be referred to as a first group of mirrors including at least one mirror. The mirror surface of the mirror 11 is provided on the concave side of the roof, and the mirror surface faces the projection lens 6.

As shown in FIG. 2B, the screen 2 has a rectangular shape having a short side 2a and a long side 2b, and the mirror 11 is long at the center of the short side 2a of the screen 2. It extends parallel to the edge on the side 2b. Therefore, the light flux emitted from the projection lens 6 is reflected by the mirror surface of the roof 11 of the mirror 11 and goes up and down in the direction of the short side 2a. Further, in the case of a projection type display device for performing color display, the liquid crystal panel 5 corresponding to the three components of R, G and B is provided with the light source 3, the condenser lens 4,
They are arranged side by side in the direction of the long side 2b together with the projection lens 6.

The remaining mirrors 21 to 28 are called the second group of mirrors, and the two light beams split by the mirror 11 are reflected by the respective mirrors to be bent and combined so as to form a predetermined image on the screen 2. It is a thing. The mirror 11 and the mirrors 21 to 28 are arranged in line symmetry with respect to a line passing through the optical axis of the projection lens 6. The mirrors 21, 22, 23, 24 are on one side of the optical axis of the projection lens 6, and the mirrors 25, 26, 27 are on the other side. The mirrors 21 to 24, 25 to 28 on the respective sides may be relatively small as long as they have the size of the divided luminous flux, and in particular, the mirrors 24 and 28 are arranged so as to cover the screen 2, The overall arrangement can be made compact. The arrangement of the mirrors 21 to 24 and 25 to 28 on each side will be described by the next progression of the light flux.

The light flux reflected by the lower half of the mirror 11 goes upward, and the light flux reflected by the upper half goes downward. At this time, the two light fluxes are divided such that the directions from the light flux portion a corresponding to the central portion of the original light flux to the light flux portion b corresponding to the peripheral portion are opposite to each other. On each side, the light flux, including the central portion a and the peripheral portion b, is reflected by the first mirror 21, 25 of the second group of mirrors and then sequentially by the mirrors 22-24, 26-28. To be done. Although the final mirrors 24 and 28 are arranged so as to cover the screen 2, the portion a of the luminous flux corresponding to the central portion of the original luminous flux comes to the central portion of the screen 2 due to the positional relationship with the previous mirrors. And the portion b of the light flux corresponding to the peripheral edge of the original light flux is
Reflect it so that it comes to the peripheral edge of. Therefore, the upper and lower light fluxes are combined on the screen 2 to obtain a predetermined image. This image is shown, for example, by the dashed lines in FIG.
The image is the same as the image formed by the light flux projected from the liquid crystal panel 5 and the projection lens 6 corresponding to the above configuration.

In the second embodiment shown in FIG. 3, the mirror 11 serving as the first group of mirrors is formed in a roof shape, and the mirror surface of the mirror 11 is provided on the convex side of the roof shape.
Further, the second group of mirrors is composed of a smaller number of mirrors 21 to 26 on each side than in the above embodiment. The other structure is almost the same as that of the first embodiment.

In this embodiment, the light flux reflected by the upper half of the mirror 11 travels upward, and the light flux reflected by the lower half travels downward. Therefore, the divided luminous flux is
When reaching the first mirror 21, 24 of the group, a portion a of the luminous flux corresponding to the central portion and a portion b of the luminous flux corresponding to the peripheral portion
The relationship with and is the reverse of the case of the first embodiment, and therefore, with one less mirror on each side, it is possible to obtain a composite image on the screen 2 as in the case of the first embodiment. ..

In the embodiment shown in FIGS. 2 and 3, the liquid crystal panel 5 and the projection lens 6 are arranged in the direction toward the screen 2. In the third embodiment shown in FIG. 4, the liquid crystal panel 5 and the projection lens 6 are arranged in the opposite direction away from the screen 2. The mirror 11 serving as the first group of mirrors is formed in a roof shape, and the mirror surface of the mirror 11 is provided on the convex side of the roof shape. Further, as in the case of the first embodiment, the mirrors 21 to 28, which are the second group of mirrors, are bent by reflecting the light beams split by the mirror 11 to obtain the combined image on the screen 2. You can

FIG. 6 is a diagram showing a fourth embodiment of the present invention for implementing the principle shown in FIG. The projection type display device shown in FIGS. 5 and 6 includes a screen 2 arranged on the front surface of a housing 1 of the device, and a light source 3, a condenser lens 4, a liquid crystal panel 5, and a projection lens arranged inside the housing 1. It consists of 6 and 6. Further, a plurality of mirrors 12, 21 to 23, which bend the light flux, are provided between the projection lens 6 and the screen 2. In this case, the mirror 12 is the first group of mirrors that split the light beam, and the remaining mirrors 21 to 23 are the second group.
It is a group of mirrors. Further, the condenser lens 4, the liquid crystal panel 5, and the projection lens 6 are not on a perpendicular line standing in the substantially central portion of the screen 2 and are arranged in a relationship substantially parallel to the screen 2.

In FIGS. 5 and 6, the mirror 12 receives a part of the light beam emitted from the projection lens 6 and is reflected by the mirror 21.
It is configured so that the light beam reflected toward and that the light beam emitted from the projection lens 6 does not receive the rest of the light beam and passes through that side toward the mirror 23. In this way, the mirror 12 splits the light beam emitted from the projection lens 6 into two light beams. Of the second group of mirrors 21-23,
The mirrors 21 and 22 bend a part of the divided luminous flux to guide it to the screen 2, and the other mirror 23 bends the other portion of the luminous flux to guide it to the screen 2. The second group of mirrors 21 to 23 is configured to direct the light beams to the screen 2 so that the optical path lengths of these two light beams are the same.

Also in this embodiment, the light flux emitted from the projection lens 6 is split by the mirror 12 into two light fluxes, and the light fluxes that are not split are bent by the mirrors 21 to 23 that bend the split light flux. In this case, the size of the mirror can be made smaller than that in the case, and the depth of the device can be made small and the height can be made small by repeating the bending of the light beam by the small mirror. Further, for example, the size of the mirror 21 located below the screen 2 is smaller than that of the mirror 7 in FIG. 10, and there is a difference in the angle with respect to the screen 2. Therefore, the area other than the screen 2 occupies in the front of the housing 1. Can be reduced.

FIG. 7 shows a fifth embodiment of the invention which is similar to the embodiment of FIG. 6 and has a screen 2 similar to that described above,
It includes a light source 3, a condenser lens 4, a liquid crystal panel 5, a projection lens 6, and a plurality of mirrors 12, 21 to 23, which are located between the projection lens 6 and the screen 2 and bend the light flux. In this case, the mirror 12 is the first group of mirrors that splits the light beam as in the fourth embodiment, and the remaining mirrors 21 to 25 are the second group of mirrors. The mirror 23 in FIG. 6 is replaced by three mirrors 23 to 23 in FIG.

FIG. 8 shows a sixth embodiment of the invention which is similar to the embodiment of FIG. 6, with a screen 2 similar to that described above,
The light source 3, the condenser lens 4, the liquid crystal panel 5, the projection lens 6, and a plurality of mirrors 12, 12a, 21 between the projection lens 6 and the screen 2 for bending the light flux.
~ 23. In this case, the mirrors 12 and 12a are the first group of mirrors that split the light beam as in the fourth embodiment, and the remaining mirrors 21 to 23 are the second group of mirrors. That is, the first mirror 12 reflects all the light flux projected from the projection lens 6, but the second mirror 12a receives a part of the light flux emitted from the projection lens 6 (and reflected by the mirror 12) and is directed to the mirror 21. Reflected towards,
In addition, the light flux emitted from the projection lens 6 (and reflected by the mirror 12) is not received, but is passed through that side to be directed to the mirror 22. The mirrors 12a and 23 of FIG. 8 and the mirror 2 of FIG.
2 and 24 are placed back to back.

In FIG. 8, the first group of mirrors 12, 1
2a is configured to divide the light beam emitted from the projection lens 6 into a thick light beam and a thin light beam. Therefore, the second
Of the group of mirrors 21 to 23, the mirror 21 reflects a thick light beam toward the screen 2 and the mirror 23 reflects a thin light beam toward the screen 2.

Further, in FIG. 8, the light source 3, the condenser lens 4, the liquid crystal panel 5, and the projection lens 6 are arranged on the back side of the reflecting surface of the mirror 21 which reflects a thick light beam toward the screen 2. It The mirror 21 is arranged so as to be inclined, and the back side of the mirror 21 in the housing 1 is a space that tends to become a dead space. In this embodiment, by utilizing this space, the light source 3 and the condenser lens 4 are provided. Thus, the installation space for the liquid crystal panel 5 and the projection lens 6 can be saved, the housing 1 can be downsized, and the screen 2 can be placed in front of the housing 1 in a well-balanced manner.

[0025]

As described above, according to the present invention,
By dividing the light flux emitted from the projection lens into a plurality of light fluxes by the first group of mirrors, the size of the second group of mirrors 4 after which the divided light flux is bent is not changed. The length in the horizontal direction can be reduced and the size in the height direction can be reduced by repeating the bending of the light beam by the small mirror. Further, it becomes possible to appropriately arrange an optical system such as a projection lens between the mirrors or on the back side of the mirrors or the like, and it is possible to reduce the vertical bending of the position of the screen on the housing.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

2A and 2B are views showing a first embodiment of the present invention, FIG. 2A is a view showing the inside of the housing, and FIG. 2B is a front view of the housing.

3A and 3B are diagrams showing a second embodiment of the present invention, in which FIG. 3A is a view showing the inside of the housing, and FIG. 3B is a front view of the housing.

4A and 4B are views showing a third embodiment of the present invention, in which FIG. 4A is a view showing the inside of the housing, and FIG. 4B is a front view of the housing.

FIG. 5 is a diagram illustrating another principle of the present invention.

FIG. 6 is a diagram showing a fourth embodiment of the present invention.

FIG. 7 is a diagram showing a fifth embodiment of the present invention.

FIG. 8 is a diagram showing a sixth embodiment of the present invention.

FIG. 9 is a diagram showing a conventional technique.

10A and 10B are views showing another conventional technique, in which FIG. 10A is a view showing the inside of the housing, and FIG. 10B is a front view of the housing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Housing 2 ... Screen 3 ... Light source 4 ... Condenser lens 5 ... Liquid crystal panel 6 ... Projection lens 11, 12, 12a ... Mirror 21-28 ... Mirror

Claims (8)

[Claims] 1. An image forming means (5) for forming a light flux of an image, a projection lens (6) for enlarging and projecting the light flux formed by the image forming means, and a light flux projected by the projection lens. In a projection type display device comprising a transmissive screen (2) for forming an image and a plurality of mirrors for bending a light beam between the projection lens and the transmissive screen, the plurality of mirrors are provided from the projection lens. A first group of mirrors (11, 12, 12) including at least one mirror that divides the emitted light flux into a plurality of light fluxes.
a) and a second group of mirrors (21 to 2) that combine the divided plurality of light fluxes so that they are bent and reflected to form a predetermined image on the screen (2).
8) A projection type display device comprising: 2. The projection lens (6) and the first group of mirrors are arranged on a vertical line standing substantially in the center of the screen, and the first group of mirrors (11) and the second group of mirrors (11). 21. The projection display device according to claim 1, wherein each of 21 to 28) is composed of a plurality of mirrors arranged in a line-symmetrical relationship with respect to a line passing through the optical axis of the projection lens (6). 3. The first group of mirrors (11) splits the light flux emitted from the projection lens (6) into two light fluxes such that the directions from the central portion toward the peripheral edge are opposite to each other, and The final mirror of the second group of mirrors (21-28) is provided near the screen (2) so as to be inclined outward so as to cover the screen (2).
The projection type display device described in. 4. The screen has a rectangular shape having a short side and a long side, and the first group of mirrors directs a light beam emitted from the projection lens in a direction corresponding to the short side of the screen. The projection type display apparatus according to claim 1, wherein the projection type display apparatus is arranged so as to perform. 5. The first group of mirrors (12, 12a) receives and reflects a part of the luminous flux emitted from the projection lens (6) and reflects the rest of the luminous flux emitted from the projection lens (6). It is composed of at least one mirror that splits into two light fluxes by passing through that side without being received, and the mirrors (21 to 23) of the second group have the same optical path length of the two light fluxes. The projection display device according to claim 1, wherein the projection display device is configured so as to face the screen (2). 6. The mirror according to claim 5, wherein the first group of mirrors (12, 12a) divides the light beam emitted from the projection lens (6) into a thick light beam and a thin light beam. The projection display device described. 7. At least two of the constituent mirrors of the first group of mirrors (12, 12a) and the second group of mirrors (21-25) are arranged back to back. 5. The projection display device according to item 5. 8. The back side of the reflecting surface of one of the constituent mirrors (21) of the first lens group (12, 12a) and the second lens group (21-25). The projection display device according to claim 5, wherein the projection display device is arranged in