JPH06301115A - Crt projection type display device - Google Patents

Abstract

PURPOSE:To sharply improve the contrast of a projected image by eliminating the reflected light generated in a spacer connecting a CRT and a projection lens. CONSTITUTION:A CRT 1 and a projection lens 2 are connected by a spacer 4, a cooling liquid 5 is sealed in it to form a CRT projection type display device, and a cylindrical light absorbing member 18 is arranged at the position along the inner face of the spacer 4. The light absorbing member 18 has a refraction factor near that of the cooling liquid 5, and it is made of a material mixed with a light absorbent at some thickness. The reflected light 12 generated in the spacer 4 transmits the boundary surface between the light absorbing member 18 and the cooling liquid 5 and is efficiently absorbed without generating the reflected light. The unnecessary light flux generated by the reflection from the face of a lens 8 is absorbed and not mixed into the effective light flux 11a, and a high-contrast image can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CRT projection type display device copying apparatus capable of easily obtaining a large screen image.

[0002]

2. Description of the Related Art FIG. 9 is a side view of a conventional CRT projection type display device, and FIG. 10 is a sectional view of the main part thereof. In the figure,
1 is a CRT, 2 is a projection lens, 3 is a screen, 4 is a spacer for optical coupling, 5 is a cooling liquid, 6
Is a packing material, 7 is a fluorescent screen, 8 is a lens in contact with the cooling liquid, 9 is the front face of the CRT face plate, 10 is a blackening treatment applied to the inner surface of the spacer 4, and 11 is a luminous flux emitted from the fluorescent screen 7. Is.

Normally, the CRT 1 and the projection lens 2 are
Although it is composed of red, blue, and green monochrome CRTs and three projection lenses, only one set is shown here for convenience of explanation. As shown in FIG. 9, the image drawn on the phosphor screen of the CRT 1 is enlarged and projected by the projection lens 2 and imaged on the screen 3.

As shown in FIG. 10, the optical coupling includes a projection lens 2 and a projection lens C on both sides via a spacer 4.
The RT 1 is fixed, and the cooling liquid 5 is sealed in the spacer 4 and shielded by the packing material 6, so that the cooling liquid does not leak. The inner surface of the spacer 4 is subjected to blackening treatment 10 such as alumite treatment or blackening paint to absorb the reflected light 12.

As described above, in the CRT projection type display device, as shown in FIG.
Since it is optically coupled by
The light flux 11 emitted from the fluorescent screen 7 of the RT 1 has a small difference in refractive index at the interface between the front face 9 of the face plate and the cooling liquid 5, so that generation of reflected light (hereinafter, also referred to as “unnecessary light”) 12 can be suppressed. , Which has helped to dramatically improve the contrast.

[0006]

Since the conventional CRT projection type display device is constructed as described above, it has the following problems.

The optical coupling by the cooling liquid 5 is not applied to the entire front surface 9 of the face plate of the CRT 1 as shown in FIG. 11, and is thin outside the packing material 6 between the spacer 4 and the spacer 4. The layer 13 is formed.

Therefore, the unnecessary light beam 11b emitted from the peripheral portion of the phosphor screen 7 generates a large reflected light 12 due to the difference in refractive index at the interface between the front face 9 of the face plate and the air layer 13. Further, since the side surface 14 of the face plate is also in contact with the air, a light flux 12 that is reflected and multiple-reflected is generated here, and these reflected lights 12 are re-incident on the fluorescent surface 7 and diffused by the fluorescent material having a high reflectance. Since it is reflected and emitted toward the projection lens 2 again, it is one of the factors that significantly deteriorates the contrast of the projected image.

Further, in FIG. 10, the effective luminous flux 11a
When entering the lens 8, a large reflected light component does not occur due to the effect of optical coupling on the first surface in contact with the cooling liquid 5 and the effect of a non-reflective coating (not shown) on the second surface. In the case of a light beam having a large incident angle on the lens surface, a slight amount of reflected light 12 is generated. The reflected light 12 is reflected or irregularly reflected by the blackening treatment 10 on the inner surface of the spacer 4 as shown in the figure, and is re-incident on the fluorescent screen 7, which is one of the causes of deterioration of contrast.

Blackening treatment 10 on the inner surface of the conventional spacer 4
Is performed by applying a black paint or arranging a separate opaque black light absorbing member, but the absorption efficiency is low and the reflectance is to some extent. Therefore, the unnecessary light 12 cannot be completely absorbed.

The present invention has been made to solve the above-mentioned problems, and increases the effect of the optical coupling method using a cooling liquid, and blocks unnecessary light with a simple structure to provide a CRT projection with good contrast. The purpose is to obtain a mold display device.

[0012]

According to the present invention, a light absorbing film is formed on the front and side surfaces of a face plate of a CRT that are not in contact with the cooling liquid.

In addition, a light absorption film is formed on the front surface of the face plate of the CRT up to the surface area that does not block the outermost effective light flux connecting the periphery of the effective area of the fluorescent surface of the CRT and the periphery of the entrance pupil of the projection lens. is there.

Further, instead of the light absorbing film, a non-reflective coating with an interference film is applied to the surface outside the contact area between the front face of the CRT and the cooling liquid.

Further, a light absorbing member formed of a member having a refractive index substantially the same as that of the cooling liquid and containing a light absorbing material is arranged along the inner surface of the spacer.

Further, inside the spacer, a light absorbing member having a refractive index substantially the same as that of the cooling liquid and formed of a material mixed with a light absorbing material is arranged at a position where the effective light flux emitted from the CRT is not shielded. It was done.

Further, the light absorbing member is composed of a polarizing plate and is arranged so as to absorb the light flux of the polarization component in the circumferential direction with respect to the optical axis of the projection lens.

[0018]

The light absorbing film which covers the front and side surfaces of the face plate of the CRT, which does not come into contact with the cooling liquid, absorbs the unnecessary luminous flux emitted from the fluorescent screen and suppresses the generation of unnecessary reflected light.

Further, since the light absorption film is provided up to the surface area which does not block the outermost effective light flux connecting the peripheral area of the effective area of the phosphor screen of the CRT and the peripheral area of the entrance pupil of the projection lens, only the effective light flux is provided on the front surface of the face plate. To emit the unwanted light flux.

Further, the anti-reflection coating by the interference film provided on the surface area of the front surface of the face plate of the CRT which is not in contact with the cooling liquid transmits the unnecessary light flux emitted from the fluorescent screen and does not generate reflected light.

Further, the light absorbing member provided along the inner surface of the spacer has substantially the same refractive index as that of the cooling liquid, and the light absorbing member mixed with the light absorbing material efficiently absorbs the reflected light from the lens.

Further, since the light absorbing member having the same refractive index as that of the cooling liquid disposed inside the spacer and containing the light absorbing material is provided at the position where the effective light flux is not blocked, the light absorbing member is emitted from the fluorescent screen. The unnecessary light flux and the reflected light from the lens are efficiently absorbed.

Further, the polarizing plate including a light absorbing material arranged in the spacer so as to absorb the light flux of the polarization component in the circumferential direction with respect to the optical axis of the projection lens is
It absorbs the S-polarized component, which occupies most of it.

[0024]

【Example】

Example 1. A first embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a cross-sectional view schematically showing the optical coupling portion of the first embodiment, and illustration of spacers and the like is omitted. Reference numeral 15 is a light absorbing film, specifically, a black paint is applied or baked from the surface area of the front surface 9 of the face plate which is not in contact with the cooling liquid 5 to the side surface 14 so as to be adhered so that an air layer is not formed therebetween. Is formed.

When this light absorbing film 15 is provided, the unnecessary light flux 11 emitted from the peripheral portion of the fluorescent screen 7 and traveling toward the spacer 4 is formed.
b is absorbed and no reflected light is generated. On the other hand, since the portion that comes into contact with the cooling liquid is optically coupled, the reflected light is transmitted without being generated.

As a result, the luminous flux 11 emitted from the fluorescent screen 7
Is transmitted through the portion in contact with the cooling liquid 5 and is absorbed by other portions, so that generation of unnecessary light reflected near the fluorescent screen 7 and returning to the original fluorescent screen is suppressed, and the projected image The contrast is improved.

The light absorption film 15 may be adhered to the CRT 1 and the spacer 4 using an adhesive or a gel-like soft material so that an air layer is not formed between them. The adhesive or gel-like soft substance is preferably a substance mixed with a light flux absorbing material.

Example 2. The second embodiment is shown in FIG. In the second embodiment, the light absorption film 15 is formed in a surface area outside the effective light flux emission area on the front surface of the face plate of the CRT.

As shown in FIG. 2, the effective luminous flux emission area is an effective area that connects the outermost side portions A and B of the effective light emission area on the phosphor screen 7 and the innermost peripheral portion of the entrance pupil 16 of the projection lens 2. Luminous flux 1
1a is a region that passes through the front face 9 of the face plate.

According to the second embodiment, since the unnecessary light beam 11b is absorbed by the light absorbing film 15 and does not exit, the light beam which enters the projection lens 2 to generate reflected light or diffusely reflects on the inner surface of the spacer 4 is generated. Since it is not generated, the contrast is improved.

Example 3. A third embodiment is shown in FIG. In the first and second embodiments, the unnecessary light flux 11b is absorbed by the light absorption film 15 formed on the outer surface of the CRT 1, but this embodiment 3
Then, the antireflection coating 17 is applied to the surface area of the front surface 9 of the face plate of the CRT 1 which is not in contact with the cooling liquid 5. When the antireflection coating 17 is applied, the unnecessary light flux 11b transmits the reflected light without generating reflected light at the interface with the air layer. The transmitted light beam 11b is absorbed by the blackening process 10 performed on the spacer 4. As a result, the contrast of the projected image is improved.

The antireflection coating 17 may be formed of a vapor-deposited multilayer film of a dielectric or metal, or may be a single-layer interference film formed by dipping.

Example 4. The fourth embodiment is shown in FIG. In the figure, reference numeral 18 is a light absorbing member provided along the inner surface of the spacer 4.

The light absorbing member 18 is formed of a substance having a refractive index close to that of the cooling liquid 5, for example, a polymeric material such as acrylic and a light absorbing material such as a dye or a pigment diffused therein. For example, the refractive index of the acrylic plate is 1.49, whereas the refractive index of the cooling liquid 5 is about 1.39 to 1.48, so that the reflected light at the interface between the cooling liquid 5 and the light absorbing member 18 is The components can be small enough to be ignored. Further, since the cylindrical light absorbing member 18 has a certain thickness,
Since the reflected light 12 is efficiently absorbed while being transmitted, the absorption efficiency is significantly higher than that of the blackening process of the conventional example, and the contrast of the projected image is improved.

This effect can be further improved if the inner surface of the spacer 4 is also subjected to a blackening treatment 10 (not shown) as in the conventional example. This cylindrical light absorbing member 1
No. 8 is particularly effective when the absorbent material density per unit thickness is made as low as possible, and is formed to a thickness of, for example, 1 mm or more.

Example 5. A fifth embodiment is shown in FIG. In the fourth embodiment, the light absorbing member 18 is arranged along the inner surface of the spacer 4. However, in the fifth embodiment, the light absorbing member 19 made of the same material is included in the light flux entering the projection lens 2 from the CRT 1. , The effective luminous flux 11 used to form an image
It is arranged as close as possible to the point where a is not blocked.
As shown in FIG. 5, if the form is along the outermost periphery of the effective light flux 11a, the reflected light 12 can be efficiently absorbed. It is more effective to dispose the annular light absorbing member 19 as close to the projection lens 2 as possible. Here, as shown in FIG. 5, the effective luminous flux 11a is bounded by the effective luminous flux 11a connecting the outermost sides A and B of the effective light emitting area of the phosphor screen 7 and the innermost peripheral portion of the pupil 13 of the projection lens 2. To be
As a result, the shape of the light absorbing member 19 may be annular or rectangular.

Example 6. In the sixth embodiment, the light absorbing member in the fifth embodiment is composed of the polarizing plate 20 shown in FIG. As shown in FIG. 7, the polarizing plate 20 has a function of transmitting only a component in one direction (Y direction) of the vibration components of light in the X and Y2 directions orthogonal to each other and absorbing a vibration component in the other direction. Have.

The reflected light 12 shown in FIGS. 4 and 5 is generally the reflected light 1 of the light beam 11 incident on the lens 8 at a large incident angle.
It is 2. As shown in FIG. 8, the component of the reflected light 12 is dominated by the S-polarized component because the incident angle is large, and if the S-polarized component is absorbed, most of the reflected light 12 can be prevented.

In the sixth embodiment, as shown in FIG. 6, a polarizing plate 20 formed in, for example, an annular shape is used as the light absorbing member 19 of FIG.
It is possible to absorb the S-polarized component corresponding to the circumferential direction and improve the contrast of the projected image.

If this polarizing plate 20 is made of a polymer material having a refractive index close to that of the cooling liquid 5, this effect can be obtained without generating new reflected light at the interface with the cooling liquid.

If it is difficult to form an annular shape as shown in FIG. 7, the polarizing plate 20 may be divided into a plurality of pieces and rectangular ones may be arranged in an annular shape. Further, a rectangular ring shape may be formed along the effective luminous flux.

[0042]

According to the present invention, since the light absorption film is formed on the front surface and the side surface of the CRT face plate outside the effective luminous flux emission region which is not in contact with the cooling liquid, the unnecessary luminous flux emitted from the fluorescent surface is absorbed. Since the generation of reflected light is suppressed, the contrast of the projected image is improved.

Further, since the light absorption film is formed on the front surface of the CRT face plate up to a region which does not block the outermost effective light flux connecting the outer peripheral portion of the effective fluorescent screen area of the CRT and the inner peripheral portion of the entrance pupil of the projection lens, the effective light flux is formed. Since only the light is emitted from the front surface of the face plate and other unnecessary light is absorbed, the contrast of the projected image is improved.

Further, since the antireflection coating by the interference film is applied to the front surface of the face panel outside the contact area of the CRT with the cooling liquid, the unnecessary light beam emitted from the fluorescent screen is transmitted and the reflected light is not generated. Therefore, the contrast of the projected image is improved.

Further, the inner surface of the spacer is provided with a light absorbing member having a refractive index substantially the same as that of the cooling liquid and having a thickness mixed with the light absorbing material, so that the light reflected from the lens is efficiently transmitted. Since it is absorbed, the contrast of the projected image is improved.

In addition, the light absorbing member having a refractive index substantially the same as that of the cooling liquid inside the spacer and a light absorbing material mixed therein is CR
Since it is provided at a position where the effective light flux emitted from T is not blocked, it absorbs the unnecessary light flux emitted from the fluorescent screen and absorbs the reflected light from the lens, thereby significantly improving the contrast of the image.

Further, since the light absorbing member is composed of a polarizing plate, it absorbs the S-polarized light component which occupies most of the reflected light from the lens, so that the contrast of the projected image is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a first embodiment of the present invention.

FIG. 2 is a sectional view of an essential part of the second embodiment of the present invention.

FIG. 3 is a sectional view of an essential part of a third embodiment of the present invention.

FIG. 4 is a sectional view of an essential part of a fourth embodiment of the present invention.

FIG. 5 is a sectional view of an essential part of a fifth embodiment of the present invention.

FIG. 6 is a diagram showing an annular polarizing plate which is a main part of a sixth embodiment of the present invention.

FIG. 7 is an explanatory diagram of an absorption function of a polarizing plate.

FIG. 8 is an explanatory diagram of reflected light characteristics of a polarizing plate.

FIG. 9 is a diagram showing a configuration of a conventional CRT projection display device.

FIG. 10 is a cross-sectional view of a conventional CRT projection display device.

FIG. 11 is a cross-sectional view of a main part for explaining the reason for lowering the contrast in the conventional CRT projection display device.

[Explanation of symbols]

 1 CRT 2 Projection Lens 3 Screen 4 Spacer 5 Cooling Liquid 7 Fluorescent Surface 8 Lens 9 Front Faceplate 10 Blackening Treatment 11 Light Beam 11a Effective Light Beam 11b Unwanted Light Beam 12 Reflected Light (Unnecessary Light) 14 Faceplate Side Surface 15 Light Absorbing Member 16 Incident Pupil 17 non-reflective coating 18 light absorbing member 19 light absorbing member 20 polarizing plate

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[Procedure amendment]

[Submission date] June 28, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

Example 5. A fifth embodiment is shown in FIG. In the fourth embodiment, the light absorbing member 18 is arranged along the inner surface of the spacer 4. However, in the fifth embodiment, the light absorbing member 19 made of the same material is included in the light flux entering the projection lens 2 from the CRT 1. , The effective luminous flux 11 used to form an image
It is arranged as close as possible to the point where a is not blocked.
As shown in FIG. 5, if the form is along the outermost periphery of the effective light flux 11a, the reflected light 12 can be efficiently absorbed. It is more effective to dispose the annular light absorbing member 19 as close to the projection lens 2 as possible. Here, as shown in FIG. 5, the effective luminous flux 11a is bounded by the effective luminous flux 11a connecting the outermost sides A and B of the effective light emitting area of the phosphor screen 7 and the innermost peripheral portion of the pupil 13 of the projection lens 2. It is.
Result of this, the shape of the light-absorbing member 19 may be an annular or rectangular ring.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

[0044] Also, out of the face panel front than the contact area between the CRT coolant, so subjected to non-reflection coating due to interference film does not generate a reflected light by transmitting non Yohikaritaba that is emitted from the phosphor surface Therefore, the contrast of the projected image is improved.

Claims (6)

[Claims] 1. A projection display device for enlarging and projecting an image formed on a phosphor screen of a CRT onto a screen through a projection lens attached through a spacer filled with a cooling liquid, wherein a side surface of a face plate of the CRT. And a light absorption film applied to the outer surface of the surface area which is not in contact with the cooling liquid on the front surface. 2. A light absorption film is applied to the front surface of the face plate of the CRT up to a region which does not block the outermost effective light flux connecting the peripheral portion of the effective area of the phosphor screen of the CRT and the peripheral portion of the entrance pupil of the projection lens. Claim 1 characterized in that
A CRT projection display device according to the item 1. 3. A projection display device for magnifying and projecting an image formed on a phosphor screen of a CRT onto a screen through a projection lens attached through a spacer filled with a cooling liquid, the front face of the face plate of the CRT. CR which is characterized in that the outer surface of the surface area which is not in contact with the cooling liquid is coated with an anti-reflection coating by an interference film.
T projection display device. 4. A projection display device for enlarging and projecting an image formed on a fluorescent screen of a CRT onto a screen by using a projection lens mounted via a spacer filled with a cooling liquid, wherein the inner periphery of the spacer is provided. A CRT projection display device characterized in that a light absorbing member made of a member having a refractive index substantially the same as that of a cooling liquid and a light absorbing material mixed therein is disposed on the surface. 5. A projection type display device for magnifying and projecting an image formed on a phosphor screen of a CRT onto a screen through a projection lens attached through a spacer filled with a cooling liquid, wherein a refractive index is provided inside the spacer. Is almost the same as the cooling liquid, and a light absorbing member made of a material mixed with a light absorbing material is arranged at a position to shield unnecessary reflected light without blocking the effective light flux emitted from the CRT. CRT projection display device. 6. The light absorbing member is a polarizing plate, and the polarizing plate is arranged so as to absorb a light flux of a polarization component in the circumferential direction with respect to the optical axis of the projection lens. The CRT projection display device according to claim 5.