JPS5942714B2 - 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 such as ZnS:Ay and Zn.
CdS: Al, ZnS: Au/Λl or Zn(S,
Be): White color is obtained by mixing a phosphor that emits yellow light such as Cu.

On the other hand, the body color of the phosphor is generally white for ZnS:Λθ which emits blue light, but ZnCdS:Ay or Z
Those that emit yellow light, such as nS:Au/Al, have a yellow body color due to their composition.

However, the body color of the phosphor surface using a phosphor made of a mixture of these materials also appears yellow. When a black-and-white image is projected on a cathode ray tube like this, no light is emitted.

The drawback is that the dark areas appear dark yellow due to the body color of the phosphor, and the image is not completely black and white. The present invention eliminates this drawback and uses blue-emitting phosphor particles (ZnS:Ay
) has a yellow body color by coating its surface with a blue material such as cobalt aluminate (ZnS:A
When mixed with u/A6 or ZnCdS:A, the body color of the fluorescent surface can be made gray.

Moreover, the phosphor that emits blue light is coated with a blue material.
), so there is little loss of luminance. In addition, in a cathode ray tube having a fluorescent surface that emits white light by mixing three types of phosphors: ZnS:Ag phosphor and ZnS:Au/Λl and Y202S:Eu, ZnS:A phosphor that emits blue light is used. The particles can be coated with a blue material, such as cobalt aluminate, to make the phosphor surface almost gray in nature.

In addition to blue, ZnS:ΛI phosphor particles also
Blue materials such as cobalt aluminate and Y2O2S:E
The U phosphor particles can each be coated with a red material such as red iron to make the body color of the phosphor surface almost gray.
Alternatively, it may be coated only in red. In addition, the phosphor is Y202S: instead of ZnS:Λu/Λl among the above combinations.
ZnS is also used for the fluorescent surface that emits white light with Tb.
Good results are obtained by coating the :Ag phosphor particles with a blue pigment and the Y2O2S:EU phosphor particles with a red pigment.

In the above-described cathode ray tube, dark areas do not appear yellowish, and since the color of the phosphor body is gray as a whole, it has excellent effects such as improving the contrast of black and white images. The combination of phosphors is not limited to the above, and it goes without saying that the present invention can also be applied to a phosphor surface that obtains white color by mixing at least two types of phosphors.

Claims (1)

[Claims] 1. In a cathode ray tube having a phosphor surface that emits white light by mixing at least two types of phosphors having mutually complementary colors, the body color of the phosphor surface is reduced so as to appear gray. A cathode ray tube that uses a phosphor whose surface is colored in a complementary color to other phosphors. 2. A cathode ray tube according to claim 1, which combines a blue-emitting phosphor and a yellow-emitting phosphor, and coats the blue-emitting phosphor particles with a blue material so that the body color of the phosphor surface is almost gray. . 3 A combination of three types of phosphors: a blue-emitting phosphor, a yellow-emitting phosphor, and a red-emitting phosphor, and one or both of the blue-emitting phosphor and the red-emitting phosphor is made of a material with approximately the same color as the emitted light. The cathode ray tube according to claim 1, wherein the cathode ray tube is coated so that the fluorescent surface has a substantially gray color.