JPH06125520A - Cat projection device - Google Patents

Abstract

PURPOSE:To improve color purity by preventing surface reflection of light which is outgoing from a CRT and is made incident to a filter. CONSTITUTION:Transparent cooling liquid L of specific wavelength is filled within the space sealed by the front surface 1A of a CRT, an installation member 2, a filter 3 and a flat field lens 4. Thus, color purity is improved by preventing the surface reflection of light which is made incident to the filter 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CRT projection device for projecting an image emitted from a CRT onto a screen, and a CRT capable of providing a particularly clear color projection image.
The present invention relates to an RT projection device.

[0002]

2. Description of the Related Art A projection type television apparatus has been developed which projects an image emitted from a CRT on a screen to form a color projection image. This device projects images separated into R (red), G (green), and B (blue) on separate CRTs, respectively, and projects and synthesizes these three types of images on a screen to project color. It is designed to form an image. By the way, in this projection television device, for example, a CR for green
In the light emitted from T, a red component or a blue component may be mixed, resulting in poor color purity, resulting in deterioration of image quality. Further, the green component may be mixed in the light emitted from the red CRT, which causes the same problem. Therefore, various CRT projection devices provided with a filter for removing unnecessary light from the light emitted from each CRT have been proposed. For example, as one of the CRT projection devices, as shown in FIG.
There is known a configuration in which a transparent glass 102 is arranged on the front surface side of the RT 100 via a mounting member 101, and a space inside the mounting member 101 formed by this is filled with a colored cooling liquid 103 having specific spectral characteristics. Has been. In the figure, reference numeral 104 is a field flat lens which constitutes one of the zoom lens groups. In the CRT projection device having such a configuration, the colored cooling liquid acts as an absorption filter, and among the light emitted from the CRT, a large amount of light in a specific wavelength range is transmitted, so that unnecessary wavelength light can be removed. You can do it.

[0003]

By the way, in this projection device, of the light emitted from the CRT, the light incident on the transparent glass at an angle close to the vertical direction can be transmitted as it is, but there is no problem, but it exceeds the critical angle. Light incident at different angles is totally reflected between the transparent glass and the air outside the transparent glass, resulting in a reduction in contrast. Therefore, in order to prevent this, for example, in FIG.
A so-called optical coupling having a configuration shown in FIG. 3 in which a space between the transparent glass 102 and the transparent glass 102 is filled with a transparent liquid L is known. Further, in this method, in order to increase the heat dissipation efficiency of the CRT 100 by increasing the cooling liquid L, a convex field flattener lens 105 may be arranged on the CRT 100 side as shown in FIG. It is known and can be so configured. However, in order to add the function as a filter,
For example, when the cooling liquid L is colored, it is practically impossible to color it because the absorptance differs between the vicinity of the center of the screen and the vicinity of the periphery. In view of the above-mentioned circumstances, the present invention has an object of providing a CRT projection device that can increase color purity in an optical coupling type CRT projection device in which a space between the lens and the CRT is filled with a cooling liquid. It is what

[0004]

That is, the present invention is a CR
A CRT projection device comprising a flat plate-shaped filter for removing light other than a specific wavelength of light from T, and a field flattener lens for correcting the curvature of the image plane projected on the screen after passing through the filter. Then, the filter and the field flattener lens are mounted on the front surface side of the CRT using a mounting member, and the space between the CRT front surface and the filter formed in the mounting member and the filter and the field flattener are formed. A transparent cooling liquid having a predetermined refractive index is enclosed in a space between the lens and the lens.

[0005]

According to the present invention, the transparent cooling liquid having a predetermined refractive index is filled in each space between the CRT and the filter and between the filter and the lens for zooming, whereby the surface reflection of the filter is prevented. It can prevent and increase color purity.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a CRT projection device according to the present invention. This CRT projection device is a CR
Mounting member 2 fixed to T1, filter 3 fixed to this mounting member 2, mounting member 2, filter 3, field flattener lens 4 and C mounted on mounting member 2
The transparent cooling liquid L is filled in two sealed spaces formed by the front surface 1A of the RT1. As CRT1, R (red), G (green), B (blue)
One of the three types of CRTs that emits separated light of any color may be used. In this embodiment, a CR for green is particularly used.
Applied to T1.

The mounting member 2 is a front surface 1A of the CRT 1.
It is formed in a rectangular or square substantially cylindrical shape according to the outer shape of the above, and is fixed in a state of being in close contact with the CRT 1 side so that the transparent cooling liquid L does not leak. In addition, in the mounting member 2 of this embodiment, two sealing spaces are communicated with each other, and in order to allow the cooling liquid L to freely move in these spaces, a communication passage (not shown) is partially formed inside. Has been formed. In addition, a cooling liquid adjusting mechanism for allowing the excess cooling liquid L to escape from the sealed space or to additionally feed the insufficient cooling liquid L into the mounting member 2 in consideration of the expansion and contraction of the cooling liquid L ( (Not shown) is attached. It is more convenient to attach a cooling device to this adjusting mechanism. The filter 3 is formed in a relatively thin parallel plate shape using a plastic material which is inexpensive and easy to mold, and has a specific wavelength for the light emitted from the CRT 1, for example, this embodiment. In particular, a color filter having a spectral characteristic of high transmittance for light in the green wavelength range is used. The field flattener lens 4 constitutes a part of a lens group that performs a zooming function of the projection image projected on the screen, and has a strong concave surface on the screen side.

The transparent cooling liquid L absorbs heat generated from the CRT 1 to promote cooling of the CRT 1, and the light emitted from the CRT 1 toward the filter 3 is directed to the field flattener lens 4 without causing surface reflection. A filter having a refractive index substantially equal to that of the filter 3 is used so that the filter 3 can pass through. Therefore, according to this embodiment,
The transparent cooling liquid L is generated by the heat generated from the operating CRT 1.
When the temperature of the liquid increases and the liquid expands relatively large, the expanded excess liquid L can be discharged from the sealed space by the cooling liquid adjusting mechanism. This prevents the field flattener lens 4 from being distorted or damaged by the pressure of the cooling liquid L. Further, according to this embodiment, since the filter 3 is made of a plastic material, it can be provided at a low cost.

[0009]

As described above, according to the CRT projector according to the present invention, the space formed between the CRT and the filter and between the filter and the zoom lens has a predetermined refractive index. Since the transparent cooling liquid is enclosed, the light emitted from the CRT and directed to the filter can be transmitted through the filter without causing surface reflection, and troubles associated therewith can be eliminated, which is extremely effective.

[Brief description of drawings]

FIG. 1 is a sectional view showing a CRT projector according to the present invention.

FIG. 2 is a cross-sectional view showing a conventional CRT projection device.

FIG. 3 A conventional optical coupling type CRT
Sectional drawing which shows a projection device.

FIG. 4 C of another conventional optical coupling system
Sectional drawing which shows RT projection device.

[Explanation of symbols]

 1 CRT 2 Mounting member 3 Filter 4 Field flattener lens L Transparent cooling liquid

Claims (1)

[Claims] 1. A flat plate filter for removing light other than a specific wavelength of light from the CRT, and a field flattener lens for correcting the curvature of the image plane projected on the screen after passing through the filter. A CRT projection device, wherein the filter and the field flattener lens are mounted on the front surface side of the CRT using a mounting member, and a space between the CRT front surface and the filter formed in the mounting member and A CRT projection device characterized in that a transparent cooling liquid having a predetermined refractive index is filled in a space between the filter and the field flattener lens.