JP3527826B2 - Projection apparatus and projection type image display apparatus using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection device for enlarging and projecting an image emitted from a projection tube on a screen and a projection type image display device using the projection device.
In particular, the present invention relates to a projection device having a structure suitable for preventing a reduction in contrast due to reflection of image light emitted from a projection tube in the projection device, and a projection-type image display device using the projection device.

[0002]

2. Description of the Related Art An example of a conventional projection device is shown in FIGS. FIG. 9 is a sectional view of the projection device, and FIG. 10 is a perspective view showing the main parts of the projection device and the configuration thereof. First lens 1
And a projection tube 2 and a bracket 28 for mounting the projection tube 2 on one surface and mounting the first lens 1 on a surface facing this surface.
And a lens fixing plate 29 for fixing the first lens 1 to the bracket 28, and a refrigerant 8 filled in a space surrounded by the projection tube 2, the first lens 1 and the bracket 28. In addition, the coolant 8 is placed between the first lens 1 and the bracket.
Lens packing 9 for sealing the lens and projection tube 2
Between the bracket 28 and the bracket 28, a projection tube packing 10 for sealing the refrigerant 8 is compressed and attached.

Since the inner wall surface of the bracket 28 is a smooth surface, the light 21 emitted from the fluorescent surface 3 of the projection tube and reflected by the inner wall surface of the bracket 28 is not diffused but becomes stray light and is reflected on the fluorescent surface 3 of the projection tube. The return contrast was reduced. As a technique for preventing this, the Japanese Unexamined Utility Model Publication No. 64-46939, the bracket has been described to reduce the reflected light intensity is provided with fins on the inner wall surface adjacent to the projection tube 2.

[0004]

The image light emitted from the projection tube 2 is reflected by the inner wall surface of the bracket 28 facing the fluorescent screen 3 of the projection tube 2 and directly enters the fluorescent screen 3 of the projection tube. It becomes stray light 21. This stray light is one of the major causes of the decrease in contrast. The one described in the above publication does not consider such stray light that directly enters the fluorescent screen 3 of the projection tube, and since the fins are provided only on the surface adjacent to the projection tube 2, this stray light is prevented. It was difficult to prevent the deterioration of contrast by diffusion.

Further, the shape of the opening hole 30 of the lens fixing plate 29 for fixing the first lens 1 is circular. On the other hand, the aspect ratio of the original image displayed on the projection tube 2 is approximately similar to the aspect ratio of the screen and is about 3: 4 or 9:16, and the opening 30 is larger than necessary in the vertical direction of the original image. Therefore, a large amount of stray light other than the light rays involved in image formation passes.

Therefore, stray light propagating from the projection tube 2 side to the screen (not shown) side, and reflected by the lenses in the lens group 19 composed of a plurality of lenses located on the screen side of the first lens 1 to cause fluorescence. The stray light 22 returning to the surface 3 or the stray light 23 returning to the projection tube 2 and reflected from the lens barrel 15 holding the lens group 19 and returning to the projection tube 2 reduces the contrast.

The present invention has been made in view of the above problems, and an object thereof is to be reflected by the inner wall surface of the bracket, the lens, the inner surface of the lens barrel or the like to reach the projection fluorescent screen or the screen. It is an object of the present invention to provide a projection device having excellent contrast performance and a projection type image display device using the same, by preventing contrast reduction due to light rays such as stray light that are not directly involved in image formation.

[0008]

A projection device according to the present invention for achieving the above object is characterized by the following two features.

First, a first feature is a projection device for enlarging and projecting an original image displayed on a projection tube on a screen,
A bracket to which the projection tube is attached on one side and a lens to the other side, and a lens fixing plate for fixing the lens to the bracket are provided, and a refrigerant is provided in a space surrounded by the projection tube, the lens and the bracket. In the filled projection device, a plurality of concave and convex grooves are formed on the inner surface of the bracket which comes into contact with the coolant.

Among the inner surfaces of the bracket, the concave and convex grooves are
It is preferably formed on the inner surface of the mounting portion of the lens, which faces the projection tube surface. Of course, it may be formed on the side surface adjacent to the projection tube surface, or more preferably on both sides. Further, the concave-convex groove on the side surface may be formed in a direction not parallel to the lens optical axis, particularly in a direction substantially orthogonal to the lens optical axis.

According to the first feature, the light incident on the inner surface of the bracket, particularly the surface facing the projection tube surface (fluorescent surface) can be diffused and scattered.
It is possible to significantly reduce stray light that is reflected by the facing surface and directly enters the projection tube surface.

A second feature of the present invention is a projection device for enlarging and projecting an original image displayed on a projection tube onto a screen, wherein the projection tube is attached to one side and a lens is attached to the other side. A bracket, and a lens fixing plate for fixing the lens to the bracket,
In a projection device in which a space surrounded by the projection tube, the lens, and the bracket is filled with a coolant, the lens fixing plate is imaged in the light emitted from the original image displayed on the projection tube. The shape is such that it passes the light rays that are involved in the above and absorbs and blocks the light rays that are not involved in the image formation.

This shape is specifically a non-circular shape, particularly a rectangular shape or a polygonal shape. Furthermore, this lens fixing plate may be subjected to antireflection treatment.

Further, according to the second feature, the shape (rectangle, polygon) which passes through the aperture of the lens fixing plate and absorbs and shields the stray light outside the range of the effective ray. Therefore, it is possible to prevent stray light from reaching the fluorescent surface of the projection tube or the screen surface.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the paths of light rays in a projection apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view showing the construction of the projection apparatus, and FIG. 3 is a perspective view showing the construction of main parts.

The bracket 4 according to the present invention is manufactured by aluminum die casting. The projection tube 2 is fixed to one surface of the bracket 4 with the projection tube fixing screw 12 and the spring 13 combined therewith sandwiching the projection tube packing 10 via the projection tube fixing metal fitting 11. Bracket 4
An opening for mounting the first lens 1 is formed on the surface facing the projection tube mounting surface. The bracket 4 is provided with a screw hole for fixing the lens fixing plate 6, and the lens fixing plate 6 is fixed to the bracket 4 with the lens packing 9 and the first lens 1 sandwiched by the screw 14. It

In this state, the coolant 8 is injected from the injection port 31 into the space formed by the bracket 4, the first lens 1 and the projection tube 2. After the coolant 8 is injected, the injection port 31 is sealed by the sealing screw 17 and the O-ring 18, so that the coolant 8 does not leak out.
Since the lens packing 9 is compressed and attached between the bracket 4 and the first lens 1, the refrigerant 8 does not leak out. Since the projection tube packing 10 is compressed and attached between the bracket 4 and the projection tube 2, the refrigerant 8 does not leak out. A diaphragm 16 having elasticity is attached to the bracket 4 to absorb a change in volume of the refrigerant 8 due to a change in temperature and keep the refrigerant pressure constant.

A lens group 19 including a plurality of lenses is held by a lens barrel 15 on the screen (not shown) side of the lens fixing plate 6, and the lens barrel 15 is fixed to the bracket 4 by screws 14.

As shown in FIG. 4, the bracket 4 is provided with concavo-convex grooves 5a and 5b on a facing wall surface 4a facing a surface for fixing the projection tube and a side wall surface 4b adjacent to the projection tube fixing surface. . The bracket 4 is usually made of aluminum die-cast, and the mold releasing direction of the die-casting mold coincides with the optical axis direction of the lens because of its shape. Uneven groove 5 on the side wall surface 4b
If b is provided parallel to the optical axis, the resistance at the time of mold release is large and the accuracy of the flatness of the bracket 4 is impaired. When the concave-convex groove 5b is formed in a direction along the mold releasing direction, it is necessary to make an angle equal to or larger than the draft of the mold in order to suppress the mold release resistance. On the other hand, as shown in FIG. 5, by providing the concave-convex groove 5b of the side wall surface 4b in the direction perpendicular to the optical axis, it is possible to reduce the resistance at the time of mold release.

Next, the optical path of the light emitted from the projection tube will be described with reference to FIG. Of the light emitted from the original image projected on the fluorescent screen 3 of the projection tube 2, an effective light ray 20 involved in image formation
Propagates in the coolant 8, passes through the first lens 1, then passes through the lens group 19, and is enlarged and projected on a screen (not shown).

The light ray 24 propagates in the coolant 8 and does not enter the first lens 1, but enters the facing wall surface 4 a of the bracket 4.
The light ray 24 is stray light that does not contribute to image formation and causes contrast deterioration. However, since the concavo-convex groove 5a shown in FIG. 4 or 5 is provided on the facing wall surface 4a, the reflected light is scattered and fluorescence is emitted. The intensity of stray light returning to surface 3 is reduced. Further, by providing the uneven groove 5b on the side wall surface 4b, the stray light 24 reflected by the facing wall surface 4a is also reflected and diffused by the side wall surface 4b, so that the intensity of the stray light returning to the fluorescent surface 3 is further reduced. Also, after the light is emitted from the projection tube 2 and reflected by the side wall surface 4b, the first
The stray light 25 that passes through the lens 1 and travels toward the screen is diffused by the concave-convex grooves 5b of the side wall surface 4b, so the intensity of the stray light 25 after reflection is reduced.

As described above, by providing the concave and convex grooves 5a and 5b on the inner wall surface of the bracket, it is possible to diffuse the reflected light and reduce the intensity of the stray light which is not involved in the image formation. In addition, there is stray light that reaches the screen surface after being diffused and reflected, or stray light that returns to the projection tube fluorescent surface 3 like the stray light 23 in FIG.
When the aperture 7 of the lens fixing plate is large, the fluorescent screen 3
The light ray 32 emitted from the first ray is the same as the stray light 23 in FIG.
After passing through the lens, it becomes stray light which is reflected by the lens barrel 15 and returns to the fluorescent screen 3, but the light beam 32 is incident on the lens fixing plate 6 by narrowing the opening hole 7 as shown in FIG. Since the lens fixing plate 6 is subjected to antireflection treatment by blackening the metal by painting or the like, the light ray 32 is absorbed and shielded, and the stray light can be greatly reduced.

The shape of the aperture 7 is such that the effective light rays involved in the image formation pass through and the stray light outside the effective light ray range is absorbed and shielded so as not to reduce the brightness of the image on the screen surface. , And has an almost similar shape to the original image projected on the projection tube 2.

The shape is, for example, red as shown in FIG.
In a projection device in which projection tubes for three colors of green and blue are arranged horizontally, the original image 2 projected on the projection tube 2 arranged at the center
The shape of 6 is a polygonal shape similar to a barrel-shaped rectangle that is bulged at the center due to lens distortion and long in the width direction of the screen. Therefore, the opening hole shape 7a of the lens fixing plate 6 combined with the projection tube arranged in the center is
As shown in FIG. 7, by making the polygonal shape (similar to the shape of the original image 26) similar to a barrel-shaped rectangle whose central portion bulges in the height direction of the image and is long in the width direction of the screen, It is possible to effectively shield light rays that are out of the range of the effective light rays and cause stray light without blocking the effective light rays.

The shape of the original image 27 projected on the projection tubes arranged on the left and right sides is as shown in FIG. 6 due to the distortion of the lens and the geometric distortion caused by the projection apparatus being tilted with respect to the screen. In addition, the central portion bulges in the height direction of the image, and the height of the end portion on the center side of the screen is larger than the height of the outer end portion to form a polygonal shape similar to a trapezoid. Therefore, as shown in FIG. 7, the aperture hole shape 7b of the lens fixing plate 6 which is combined with the projection tubes arranged on the left and right has the central portion bulging in the height direction of the image and the end portion on the central side of the screen. By making the polygonal shape (similar to the shape of the original image 27) similar to a trapezoid whose height is larger than the height of the outer end, the effective light ray is not blocked and the cause of stray light outside the range of the effective light ray is It is possible to effectively shield the following light rays.

In order to effectively shield stray light, it is necessary to change the shape of the aperture hole according to the projection tube 2 as shown in FIG. 7, but as shown in FIG. Cost can be reduced by sharing the shape of the opening of the fixing plate 6 and sharing the lens fixing plate.

[0027]

According to the present invention, stray light emitted from the projection tube and reflected on the inner wall surface of the bracket is diffused and reflected by the concave and convex grooves provided on the inner wall of the bracket, so that the intensity is reduced and the contrast is improved. . In addition, the aperture of the lens fixing plate allows the effective light rays involved in the image formation to pass through and absorbs and blocks the stray light outside the effective light ray range, thereby improving the contrast without impairing the brightness of the image on the screen. Can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross section of a main part of a projection device of a projection device according to the present invention and an optical path of a light ray inside the projection device.

FIG. 2 is a sectional view showing the overall configuration of an embodiment of a projection device according to the present invention.

FIG. 3 is an exploded perspective view of an embodiment of a projection device according to the present invention.

FIG. 4 is a perspective view showing an example of a bracket applied to the projection device according to the present invention.

FIG. 5 is a perspective view showing an example of a bracket applied to the projection device according to the present invention.

FIG. 6 is a diagram showing a shape of an original image displayed on a projection tube of a three-tube projection device.

FIG. 7 is a diagram showing an example of a lens fixing plate opening hole shape applied to a projection device according to the present invention.

FIG. 8 is a diagram showing another example of the lens fixing plate opening hole shape applied to the projection device according to the present invention.

FIG. 9 is a sectional view showing the overall configuration of a conventional projection device.

FIG. 10 is an exploded perspective view of a conventional projection device.

[Explanation of symbols]

1 ... 1st lens 2 ... Projection tube 3 ... Fluorescent screen of projection tube 4 ... Bracket 4a… Wall facing the bracket 4b ... Side wall surface of bracket 5 ... Grooves on the inner wall of the bracket 5a ... Grooves on the wall facing the bracket 5b ... An uneven groove on the side wall surface 6 ... Lens fixing plate 7 ... Opening hole of lens fixing plate 8 ... Refrigerant 9 ... Lens packing 10 ... Projection tube packing 11 ... Projection tube fixing bracket 12 ... Projection tube fixing screw 13 ... Spring 14 ... Screw 15 ... lens barrel 16 ... diaphragm 17 ... Sealing screw 18 ... O-ring 19 ... Lens group 20 ... Effective ray 21, 22, 23, 25 ... Stray light

Front page continued (72) Inventor Koji Hirata, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Stock Company, Hitachi, Ltd., Video Information Media Division (72) Inventor Naoyuki Ogura, 292, Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa (56) References JP-A-60-62042 (JP, A) JP-A-62-35428 (JP, A) Actual development 64-6439 (JP, U) Actual development Sho-62 −71609 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01J 31/10

Claims (5)

(57) [Claims] 1. A projection device for enlarging and projecting an original image displayed on a projection tube onto a screen, a bracket to which the projection tube is attached on one side, and a lens on the other side, and the lens fixed to the bracket. In the projection device, which is provided with a lens fixing plate for, and in which a space surrounded by the projection tube, the lens, and the bracket is filled with a coolant, an inner surface of the bracket that is in contact with the coolant is substantially aligned with the optical axis direction of the lens. A plurality of concave and convex grooves extending in the orthogonal direction are formed , and the shape of the opening hole of the lens fixing plate is
The image in the center of the image is the dimension in the height direction.
A projection device characterized by having a barrel shape larger than the dimension in the height direction . 2. The projection device according to claim 1, wherein the concave-convex groove is formed on at least a side surface of the inner surface of the bracket adjacent to the projection tube surface. 3. The projection device according to claim 1, wherein the lens fixing plate is subjected to antireflection treatment. 4. An original image displayed on a projection tube is displayed on a screen.
A projection device for enlarging and projecting, the projection tube being installed on one side.
Bracket that is attached to the other side and the lens is attached to the other side
And a lens for fixing the lens to the bracket
A fixed plate is provided, and the projection tube, lens, and bracket are
In a projection device in which the space surrounded by
The shape of the opening of the lens fixing plate to
The dimension in the image height direction is the dimension in the image height direction at both ends.
A projection device characterized by a barrel shape larger than the law. 5. The projection device according to claim 1.
Projector-type image display device characterized by being equipped with
Place