JPH0662420A - Projection television device - Google Patents

Abstract

PURPOSE:To provide a projection TV device which can improve the contrast and can increase the color regenerating range. CONSTITUTION:A multilayer interference coating layer 3 having a high reflection factor to the light of a specific wavelength area is added into a projection lens group 2 set prior to a CRT 1. Then the display face plate glass 4 of the CRT 1 is provided with a phosphor 5 which has the high absorption factor to the light of a specific wavelength area. Thus the undesired beams among the spectrum beams supplied from the substance 5 are reflected on the layer 3 and then absorbed by the substance 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type television apparatus using a phosphor provided on the inner surface of a display window of a cathode ray tube as a display screen.

[0002]

2. Description of the Related Art FIG. 1 is a block diagram of a conventional projection television apparatus. In the figure, 1 indicates a cathode ray tube, and the cathode ray tube 1
Has a display face plate glass 4 as a display window on its front surface. On the display face plate glass 4, a phosphor 5a mainly made of a fluorescent material layer which emits light of a green wavelength as a center and an aluminum vapor deposition film 6 are laminated. In front of the cathode ray tube 1, a projection lens group 2 for projecting light from the phosphor 5a is arranged. On the frontmost lens of the projection lens group 2, a multilayer interference coating layer 3 is formed as a highly reflective member having a high reflectance characteristic with respect to light in a specific wavelength range (light other than near the green spectrum wavelength of 545 nm). Has been done. The multilayer interference coating layer 3 has a structure in which layers having a high refractive index and layers having a low refractive index are alternately laminated.

Next, the operation will be described. Cathode ray tube 1
Display phosphor 5a applied to face plate glass 4
When an electron beam is incident on, the phosphor 5a emits light centered on the green spectrum. The emission spectrum at this time is as shown by the solid line A in FIG. The cathode ray tube phosphor used in the projection television device is forced to use a fluorescent material having such an emission spectrum due to problems such as lifetime and brightness. As shown by the solid line A in Fig. 2, the originally required green spectrum wavelength is 545 nm.
Besides, the spectrum components on the blue side and the red side are also included. As a result, FIG. 3 showing a chromaticity diagram showing the color reproduction range.
At G, which is far from the standard green chromaticity point G
Only the chromaticity value of the point 0 was obtained, and the color could only be reproduced in the range of the triangle a indicated by the broken line.

Therefore, in the conventional example shown in FIG. 1, a multilayer interference coating layer 3 having a transmittance set as shown by a broken line B in FIG. 2 is provided in the projection lens group 2. And the phosphor 5a
The multilayer interference coating layer 3 reflects unnecessary spectral components having a peak at a wavelength slightly shorter than 500 nm and a wavelength around 600 nm in the light spectrum (solid line A in FIG. 2) emitted from The color reproduction range is expanded. Specifically, in FIG. 3, the chromaticity point of G1 is improved, and the color reproduction range is also improved to the range of the triangle b represented by the one-dot chain line.

[0005]

However, unnecessary light reflected by the multilayer interference coating layer 3 (highly reflective member) returns to the display face plate glass 4 as shown by the arrow in FIG. It is reflected and emitted again forward. As a result, there are problems that the contrast is lowered and the color reproduction range is insufficient.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a projection television apparatus capable of improving the contrast and sufficiently expanding the color reproduction range.

[0007]

A projection television apparatus according to the present invention is characterized by including a phosphor having a high absorptance with respect to light in a specific wavelength range (the above-mentioned unnecessary light).

[0008]

In the projection television apparatus of the present invention, unnecessary light reflected by the high reflection member is absorbed by the phosphor, so that the contrast is high and the color reproduction range is wide.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments.

FIG. 4 is a block diagram of a projection television apparatus according to the present invention. In the figure, reference numeral 1 denotes a cathode ray tube, and the cathode ray tube 1 has a display face plate glass 4 as a display window on its front surface. Display face plate glass 4
In the above, a phosphor 5 composed of a phosphor material layer which mainly emits light having a wavelength of green and a vapor deposited aluminum film 6 are laminated. In front of the cathode ray tube 1, a projection lens group 2 for projecting light from the phosphor 5a is arranged. On the frontmost lens of the projection lens group 2, a multilayer interference coating layer 3 is formed as a highly reflective member having a high reflectance characteristic with respect to light in a specific wavelength range (light other than near the green spectrum wavelength of 545 nm). Has been done. The cathode ray tube 1, the projection lens group 2, the multilayer interference coating layer 3, the display face plate glass 4, and the aluminum vapor deposition film 6 are the same as those in the conventional example shown in FIG.

The phosphor 5 is a phosphor in which a material having a high absorptivity for light in a specific wavelength range is mixed, and specifically, the transmissivity characteristic (shown by the one-dot chain line C in FIG. 2) ( Wavelength is
It has high absorptivity for light with wavelengths near 500 nm and below and wavelengths above 600 nm). Cobalt green, phthalocyanine-based or anthraquinone-based pigments, dyes and the like can be used as a mixed material for imparting such transmittance characteristics (color selection characteristics).

Next, the operation will be described. Cathode ray tube 1
Display phosphor 5 applied to face plate glass 4
When an electron beam is incident on the phosphor 5, the phosphor 5 emits light having a spectrum as indicated by a solid line A in FIG. An unnecessary spectral component having a peak at a wavelength slightly shorter than 500 nm and an unnecessary spectral component having a wavelength around 600 nm in the light spectrum emitted from the phosphor 5 (solid line A in FIG. 2) is shown by a broken line B in FIG. It is reflected by the multilayer interference coating layer 3 having such transmittance characteristics. This unnecessary reflected light is absorbed by the phosphor 5 having the transmittance characteristic as shown by the chain line C in FIG. Therefore, unlike the conventional example, this unnecessary light is not emitted again from the display face plate glass 4, the contrast is improved, and the color reproduction range is expanded. Specifically, in FIG. 3, the chromaticity point can be improved to the point of G2, whereby the color reproduction range can be expanded to the range of the triangle indicated by the chain double-dashed line c.

Although the multilayer interference coating layer 3 is used in the above embodiment, instead of this, a filter having a high reflectance for unnecessary light should be provided in the projection lens group 2 or in front of it. You may comprise.

In the above-mentioned embodiment, the green phosphor is described as an example, but it goes without saying that the present invention can be similarly applied to the red phosphor and the blue phosphor.

[0015]

As described above, in the projection television apparatus of the present invention, the fluorescent material having a high absorptivity for the light in the specific wavelength range is provided, and unnecessary light reflected by the high reflection member is fluorescent. Since it is configured to be absorbed by the body, the present invention has excellent effects such as improvement of contrast and expansion of color reproduction range.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a conventional projection television device.

FIG. 2 is a graph showing an emission spectrum from a phosphor, a reflection characteristic of a multilayer interference coating layer, and an absorption characteristic of the phosphor.

FIG. 3 is a chromaticity diagram showing a color reproduction range.

FIG. 4 is a configuration diagram of a projection television device according to the present invention.

[Explanation of symbols]

 1 Cathode Ray Tube 2 Projection Lens Group 3 Multilayer Interference Coating Layer 4 Display Faceplate Glass 5 Phosphor 6 Aluminum Evaporated Film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04N 5/74 B 9068-5C

Claims (1)

[Claims] 1. A phosphor provided on an inner surface of a display window of a cathode ray tube, a projection lens group provided in front of the cathode ray tube, and a light having a specific wavelength range provided in the projection lens group. On the other hand, in a projection television device provided with a high reflection member having a high reflectance, the phosphor has a high absorptivity for light in the specific wavelength range. .