JPH0625352B2 - Cathode ray tube - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a cathode ray tube, and more particularly to a fluorescent surface thereof.

[Technical background of the invention and its problems]

Usually, the cathode side of a cathode ray tube, for example a color picture tube, is red,
Dot-shaped or stripe-shaped groups of phosphors that emit green and blue light are regularly arranged, and if necessary, the gaps between these phosphors are coated with a non-emissive light absorbing substance. Conventionally, in such a color picture tube, in order to improve the contrast of the screen, a pigment having a color tone substantially the same as the color of the emitted light is attached to or mixed with the luminous body to reduce the external light reflectance. . However, in such a method, for example, the scattered electron scattered in the shutter mask and the metal back layer described in JP-A-56-141149, and the electron beam that is scanned a little larger than the effective fluorescent surface are used as the shutter mask. It has not been possible to sufficiently reduce the contrast reduction of the screen due to the abnormal light emission of the fluorescent body due to the reflected electrons reflected between the inner surfaces of the side wall portions of the panel.

[Object of the Invention]

It is an object of the present invention to obtain a cathode ray tube with improved screen contrast and high brightness.

[Outline of Invention]

In general, for example, JP-A-52-12561 discloses Zn
It is described that the current-luminance characteristics of the S-CdS-based phosphor can be changed by doping it with a slight amount of impurities such as Ni (the so-called super-linear phosphor), but it is used. Regarding the particle size of the optical body and the doping amount of impurities,
No description is given. Further, Japanese Patent Laid-Open No. 57-87487 discloses that (ZnMg) OP ₂ O ₅ : MnAs phosphor is doped with Co or Ni at 10 ^{−5 to} 7.5 × 10 ⁻² gram atom with respect to the phosphor. It is stated that the voltage-luminance characteristics of the phosphor can be changed, but there is no description about the optimum particle size range of the phosphor to be used and the constitutional contents thereof, and the above-mentioned JP-A-57-87487. ZnS: Ag in US Pat. No. 3,294,569 cited in
No mention is made of the optimum particle size range of the phosphor used when Co is doped and the optimum concentration of the doping material.

As described above, current luminance characteristics and voltage luminance characteristics when a small amount of ferromagnetic metal is doped in a phosphor are known, but when such a phosphor is used in a color picture tube, , The optimum particle size range of the fluorescent substance to be doped, the optimum doping amount, and the composition of the fluorescent substance, which are related to the anomalous emission of the fluorescent surface due to scattered electrons and reflected electrons in the tube, and the purpose, are completely unknown. It is difficult to optimally set the conditions that meet the above purpose.

As a result of studying the above points, the inventors of the present invention have found that if a green light-emitting phosphor with a fluorescent substance having an average particle size of 6 μ to 15 μ having a changed current luminance characteristic or voltage luminance characteristic is used, an abnormal fluorescent surface is observed. It has been found that the light emission can be most efficiently reduced without substantially reducing the brightness of the cathode ray tube.

In addition, it is not preferable to use a fluorescent substance to be doped with one having an average particle diameter of 6.0 μ or less because the luminous efficiency of the fluorescent substance is significantly reduced.

The present invention is a green-emitting phosphor doped with at least one of Fe, Co, and Ni by 0.1 ppm to 500 ppm with respect to the phosphor, and a phosphor having an average particle size of 6 μ to 15 μ, and the above ferromagnetic metal is not doped. Using a phosphor with an average particle size of 3μ to 9μ,
The mixing ratio of the latter is 1 to 50 with respect to the former 100 parts by weight.
The weight part is a high-brightness cathode ray tube which reduces the emission of green phosphor due to scattered electrons and reflected electrons to improve the contrast reduction of the screen, and has a dense fluorescent film.

The green-emitting phosphor applied to the present invention includes ZnS / Cl,
Al, (ZnCd) S / Cu, Al, ZnS / An, Cu, Al, ZnS / Au, Al and the like can be used. These phosphors applied to the present invention have a mean particle size of 6 μ to 15 μ in a phosphor doped with a ferromagnetic metal, and a mean particle size of 3 μ to 9 μ in a phosphor not doped. It is preferable that the mixing ratio of the former is 100 parts by weight and the latter is 1 part by weight.
It is preferably from 50 to 50 parts by weight.

Further, in the ferromagnetic metal used in the present invention, at least one of Fe, Co and Ni is doped in the green phosphor, and the doping amount is 0.1 ppm to 500 ppm with respect to the phosphor.

That is, the doping amount of the ferromagnetic metal with respect to the green light emitting phosphor of these various particle diameters, 0.1ppm to 500ppm, preferably 0.
It is 5 to 50 ppm. Further, the average particle diameter of the phosphor to be doped is preferably 6 μ to 15 μ, and if it is 6 μ or less, the luminous efficiency is significantly reduced by doping, and if it is 15 μ or more, the density of the phosphor layer becomes coarse, which is not preferable. .

On the other hand, the average particle size of the undoped phosphor is preferably from 3 μ to 9 μ, and when it is 3 μ or less, the dispersibility of the phosphor is poor, and when it is 9 μ or more, the improvement in the compactness of the target phosphor layer is lowered. Therefore, it is not preferable.

The mixing ratio of the above-mentioned fluorescent substance is 100 parts by weight of the former and 1 to 50 parts by weight of the latter, preferably 5 to 30 parts by weight. 1
If it is less than 50 parts by weight, the desired density of the phosphor layer will not be improved, and if it exceeds 50 parts by weight, the current luminance characteristic or the voltage luminance characteristic of the formed phosphor layer will be deteriorated, which is not preferable.

Example of Invention

 Specific examples of the present invention will be described below.

ZnS / Cu, Al phosphors with an average particle diameter of 8μ doped with Ni at 1,3,5ppm respectively 100 parts by weight, ZnS / Cu, A with an average particle diameter of 5μ
l Prepare a phosphor suspension of the following composition with 15 parts by weight of the phosphor.

100 parts by weight of doped phosphor 15 parts by weight of undoped phosphor 15 parts by weight of PVA 6 parts by weight of ADC 0.6 parts by weight of surfactant 1 part by weight of water 200 parts by weight First of all, for example, a blue light emitting fluorescent material containing ZnS / Ag, Cl with a blue pigment. A phosphor suspension in which a phosphor and an aqueous solution containing PVA and ADC are suspended is applied to the inner surface of the face plate, and the coating film is irradiated with light through a shadow mask having a predetermined pattern. Is photo-cured and the unirradiated portion is washed away to form a striped blue-emitting phosphor layer. Then, a green light emitting layer having the above composition was formed, and a red light emitting fluorescent material layer composed of Y ₂ O ₂ S / Eu with a red pigment was formed by using a conventional ADC / PUA-based resist. Produces a color picture tube.

White gauge of such a 14-inch color picture tube (9300 ° K + 27MPCD
We measured the total cathode current = WIb) and the brightness of the dark space required to obtain a white color of 32f. As shown in Fig. 1, the total current of the cathode is 300μA, and the horizontal axis (H-H) width is symmetrical to the vertical axis (Y-Y) of the screen.
A white bar with a scanning width of 23.8 mm is projected, and the center of the screen is displayed.
The white brightness was defined as (0), and the black level brightness at the point (A) at 35 mm and the position (B) at 70 mm on the horizontal axis (H-H) from the screen center (0) was defined as dark part brightness. Further, the average particle size is 6.0 with respect to the above examples.
FIG. 2 shows the result of comparing the white luminance and the dark portion luminance of the color picture tube manufactured by using μSnS / Cu, Al doped with Ni at 1, 3 and 5 ppm, respectively. Fig. 2 shows ZnS / Cu, Al
Characteristics of each color picture tube according to the above-mentioned embodiment when using green phosphors doped with Ni of 1,3,5 ppm respectively
(2) shows the reduction rate of white luminance and the reduction rate of dark area luminance of characteristic (1) of each conventional color picture tube doped with Ni and having an average particle size of 6.0 μ. Characteristics (1) and (2)
(a) to (c) show the cases of doping amounts of 1, 3, and 5 ppm, respectively. As is clear from FIG. 2, it was possible to reduce the dark area luminance at the same or a higher improvement rate as that of the conventional color picture tube without lowering the white luminance.

Although the present invention is applied to the color picture tube in the above-described embodiments, it goes without saying that the present invention can also be applied to other cathode ray tubes such as a monochromatic light emitting cathode ray tube.

〔The invention's effect〕

As described above, according to the present invention, as a green light emitting phosphor,
It is possible to improve the abnormal light emission of the fluorescent layer due to scattered electrons and reflected electrons in the tube by mixing and using the fluorescent material doped with ferromagnetic metal and the undoped fluorescent material with appropriate average particle size. Since it is possible and a dense phosphor layer can be formed, it is possible to obtain a cathode ray tube having higher contrast and higher brightness than the conventional cathode ray tube.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining measurement points of black level luminance on a fluorescent surface, and FIG. 2 is a reduction rate of dark area luminance and a reduction of white luminance of a color picture tube to which the present invention is applied and a conventional color picture tube. It is a characteristic view showing the relationship of the rate.

Claims (1)

[Claims] 1. At least one of Fe, Co, and Ni as a ferromagnetic metal is added to a green light-emitting phosphor on a fluorescent surface that emits light by cathode ray stimulation.
Zinc sulfide or zinc cadmium sulfide-based phosphor having an average particle size of 6 μ to 15 μ doped with 1 to 500 ppm, and zinc sulfide or zinc cadmium sulfide-based phosphor having an average particle size of 3 μ to 9 μ not doped with the ferromagnetic metal Using
The mixing ratio is 100 parts by weight of the former and 1 to 50 for the latter.
A cathode ray tube characterized by being a part by weight.