KR930006180Y1 - Color cathode-ray tube having filter layer - Google Patents

Abstract

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Description

Color Cathode Ray Tube with Filter Layer

1 is a monolayer structure diagram of a face showing an example of a cathode ray tube according to the present invention.

Figure 2 is a single layer structure showing another example of the present invention.

* Explanation of symbols for main parts of the drawings

2: Face 3: Low Pass Filter

4: high pass filter

The present invention relates to a color cathode ray tube coated with a filter layer for blocking a specific wavelength on the face surface.

In the color cathode ray tube, R, G, and B electron beams emitted from the electron gun are landed by R, G, and B phosphors applied to the inner surface of the face to emit color images, but the electron beams may collide with the phosphor. For example, in the case of the R phosphor, not only the red wavelength is excited from the phosphor but also partially includes interference waves having a wavelength close to the surrounding G phosphor or B phosphor, thereby reducing the contrast.

In addition, in the color cathode ray tube, the fall of color purity caused by the external light reflection in which external light is incident on the screen and reflected back is also a big problem.

In order to solve the problems of contrast reduction and external light reflection, conventionally, a colored layer or a diffuse reflection layer has been coated on the face surface, but this method only slightly improves the sharpness, and a significant improvement in color purity can be expected. There was no.

As a result of intensively examining the solution of the color purity reduction caused by external light reflection, the image displayed by the electron beam landing on the phosphor includes not only the intrinsic wavelength excited by the phosphor but also the interference wavelength excited by another phosphor. Attention was directed to filtering the wavelength band where the wavelengths of the R, G, and B phosphors cross each other to improve the color purity.

Accordingly, an object of the present invention is to provide a color cathode ray tube coated with a filter layer in which color wavelengths of light emitted from R, G, and B phosphors of a color cathode ray tube are distinguished to improve color purity and clarity.

In accordance with the above object, the present invention provides a low pass filter having a basic structure of (H / 2 LH / 2) ⁿ and a high structure of (L / 2 HL / 2) ⁿ high pass filter on the surface or front and back of the face. It is characterized in that the wavelength band of the R, G, B phosphors are distinguished by blocking the wavelength of 570 nm corresponding to the intermediate region of the R, G, phosphors by coating.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a single layer structure diagram of a face showing an example of a cathode ray tube according to the present invention.

On the inner surface, the low pass filter 3 and the high pass filter 4 are coated on the surface of the face 2 on which the R, G and B phosphors 1 are coated.

The wavelength range of each phosphor is 610-650nm for R phosphor, 510-610nm for G phosphor, 410-510nm for B phosphor, and the center wavelength is 630nm for R phosphor, 540nm for G phosphor, 450nm for B phosphor. For clarity, a combination of the low pass filter 3 and the high pass filter 4 forms a filter of a specific wavelength band.

The filter (3) (4) is formed by ZnS having a high refractive index (hereinafter referred to as H) and Na ₃ AIF having a low refractive index (hereinafter referred to as L), and the filterable wavelength band is these H and Determined by the thickness of the L layer and the relationship is as follows.

Formula] (H / 2 LH / 2) ⁿ and (L / 2 HL / 2) ⁿ Where ⁿ is the number of layers, up to seven layers are possible.

The present invention intends to block the wavelength of 570 nm corresponding to the middle region of the R and G phosphors.

Where H and L are λ / 4 (λ is the wavelength) Low pass filters with L = λ / 4 = 142.5 nm and high pass filters with H = λ / 4 = 142.5 nm and L = λ / 8 = 71.25 nm.

On the other hand, the formation of each filter 3, 4 coated on the surface of the face 2 is formed through a conventional deposition process.

In addition, each filter (3) (4) is not necessarily coated on the outer surface of the face (2), as shown in Figure 2 divided into the front and rear surfaces of the face (2) and low pass filter (3) and The high pass filter 4 may be coated.

According to the present invention as described above, when the light emitted by the electron beam impinges on the phosphor passes through the filter layer, the wavelength component harmful to the color purity emitted from the phosphor is blocked by the low pass filter or the high pass filter, Only the nearest wavelength component can be displayed as an image, which can improve the color purity of 10-30% compared to the prior art, and thus the sharpness of the image is further cleared.

Claims (1)

In a color cathode ray tube in which R, G, and B phosphors are coated on a face inner surface in a predetermined pattern, a low pass having a basic structure (H / 2 LH / 2) ⁿ on the front or front and back surfaces of the face 2. Coating the filter 3 and the high pass filter 4 having a basic structure of (L / 2 HL / 2) ⁿ to block wavelengths of 570 nm or more corresponding to the intermediate region of the R and G phosphors to block R, G, and B. Color cathode ray tube coated with a filter layer, characterized in that the wavelength band of the light emitted from the phosphor. [Wherein H is ZnS, L is Na ³ AIF, and ⁿ is at most 7;