JPS5942715B2 - cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the color of light emitted from the fluorescent surface of a cathode ray tube.

The fluorescent surface of cathode ray tubes that emit white light, such as cathode ray tubes for black and white televisions, is usually made of blue and ZnS materials such as ZnS:Ag.
:Au/Al, ZnCdS■Ag or Zn(S,
Be): White color is obtained by mixing Cu with a phosphor that emits a deep yellow color.

On the other hand, phosphors such as ZnS:Ag that emit blue light are generally white, but those that emit yellow light such as ZnS:Au/Al have a yellow body color due to their composition.

Therefore, the body color of the phosphor surface coated with a mixture of these phosphors also appears yellow. When a black-and-white image is projected on such a cathode ray tube, the dark areas that are not emitting light appear dark yellow due to the body color of the phosphor, and there is a drawback that the image is not completely black and white.

The present invention aims to improve this drawback and obtain a black and white image with good contrast in which dark areas appear dark black.

That is, a pigment having a complementary color relationship with the body color of the phosphor is mixed with the phosphor to make the body color of the phosphor surface almost gray. In the case of the black-and-white television cathode ray tube, the phosphor facet color is yellowish.

Therefore, a phosphor that emits blue light such as ZnS:Ag and ZnCdS■Ag, ZnS:Λu/All or Z
n(S, Be): In a cathode ray tube that has a fluorescent surface that emits white light by mixing a yellow-emitting phosphor such as Cu, the color of the phosphor surface can be changed by mixing a blue pigment with the phosphor. It becomes almost gray. Here, as the blue pigment, a pigment containing cobalt such as cobalt aluminate is generally used. It goes without saying that the color can be corrected by mixing not only one kind of pigment but also a small amount of red pigment such as red pigment. Although the luminance of the light emitted by the mixture of blue pigments decreases slightly, the color of the mixed pigment is different from the color of the mixed pigment because the phosphor that emits blue and the phosphor that emits yellow are mixed to produce white light. Since the colors of the blue components of the emitted light are similar, there is little reduction in luminance. In addition, the phosphor does not emit two colors, blue and yellow, but in other words, Y
202S: ι, which has three colors by adding a green-emitting phosphor such as Tb, emits white light by adding a phosphor of another color and mixing three or more types of phosphors. Needless to say, the present invention can also be applied to a cathode ray tube having a fluorescent surface.

It goes without saying that the color of the pigment is not limited to blue, but a complementary color of the pigment should be selected in accordance with the body color of the phosphor. As explained above. In the present invention, a pigment having a complementary color relationship with the phosphor body color is mixed to make the phosphor body color almost gray. The effects are significant, such as making cathode ray tube screens easier to see and improving the contrast of black and white images.

Claims (1)

[Scope of Claims] 1. In a cathode ray tube having a phosphor surface that emits white light by mixing at least two types of phosphors that have mutually complementary colors, a pigment that has a complementary color relationship to the original body color of the phosphors. A cathode ray tube with a mixed fluorescent facet color that is almost gray. 2. In a cathode ray tube that has a phosphor surface that emits white light by mixing at least a phosphor that emits blue and a phosphor that emits yellow, the color of the phosphor surface is almost the same by mixing a blue pigment with the phosphor. The cathode ray tube according to claim 1, which is gray in color.