JPH0129235B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathode ray tube for a monochrome display that emits orange light, and more particularly to a cathode ray tube for a monochrome display that has a high brightness, long afterglow, orange light emitting phosphor film.

In recent years, high-resolution display cathode ray tubes have been desired to be used in computer terminal display devices, aircraft control system display devices, etc. that display detailed characters and graphics.

The phosphor film of such a high-resolution display cathode ray tube must be composed of a phosphor with long afterglow properties. This is because if the phosphor film of the cathode ray tube is composed of a phosphor with short afterglow properties, the phosphor film scans at a slow speed, causing flickering on the screen. In general, the phosphor that makes up the phosphor film of such a high-resolution display cathode ray tube has an afterglow time (herein, the time required for the luminance to drop to 10% of the excitation level after excitation stops, or " 10% afterglow time) is required to be several tens to hundreds of times longer than that of the short afterglow phosphor that constitutes the phosphor film of an ordinary cathode ray tube.

In particular, orange-emitting, high-resolution monochrome display cathode ray tubes (hereinafter abbreviated as cathode ray tubes) are widely used in these applications because they cause less visual fatigue even when viewed for long periods of time.

Conventionally, a practical long-afterglow orange-emitting phosphor used in such cathode ray tubes is a green-emitting manganese-activated zinc silicate phosphor (P39 phosphor).
and red-emitting manganese-activated zinc phosphate phosphor (P27
A mixture of fluorescers (fluorescers) was used. However, since this phosphor is a mixture of phosphors of two completely different emission colors, color unevenness occurs when the resolution is increased, making it unsuitable for practical use and lacking in sufficient brightness. In addition, a lead- and manganese-activated calcium silicate phosphor (P25 phosphor) is known as a single phosphor that emits orange light with a long afterglow, but its luminance is extremely low and is not practical. Furthermore, since the color of the emitted light hardly changes depending on the amount of activation, etc., it was not possible to exhibit the various colors of emitted light required of a cathode ray tube.

On the other hand, in recent years, there has been a demand for cathode ray tubes that can be adapted to a wide variety of uses. It has been desired to develop a cathode ray tube whose phosphor film is a long-afterglow orange-emitting phosphor. Furthermore, compared to conventional cathode ray tubes for color television, high-resolution cathode ray tubes require significantly higher phosphor uniformity due to their functionality.
All of the P39 phosphors had particle shapes and particle size distributions that were unfavorable for coating purposes, resulting in extremely low yields in the production of cathode ray tubes, and causing significant industrial inconveniences.

An object of the present invention is to provide a cathode ray tube whose phosphor film is an orange-emitting phosphor that has a long afterglow property and can select any emission color from orange close to red to orange close to yellow.

Another object of the present invention is to provide a cathode ray tube whose phosphor film is a long-afterglow orange-emitting phosphor that emits high-intensity light.

Still another object of the present invention is to provide an orange-emitting cathode ray tube having a uniform and high-yield phosphor film.

The cathode ray tube of the present invention has a beam diameter of 0.05 to 0.4 mm on the fluorescent surface,
It is equipped with an electron gun that emits cathode rays with a frame frequency of 20 to 50 Hz, and a composition formula (Zn _1-x , Cdx) S (where x is 0.15≦x≦0.35) is placed on the face plate facing the electron gun. The base material is zinc cadmium sulfide represented by a number satisfying the range of At least one kind of aluminum is used as a second co-activator, and the amounts of the activator, the first co-activator, and the second co-activator are each 10 ^-4 with respect to the base material. ~1% by weight,
10 ^-6 to 10 ^-1 % by weight and 5 x 10 ^-6 to 5 x 10 ^-1 % by weight of a long-afterglow orange-emitting phosphor. That is.

The phosphor film of the cathode ray tube of the present invention may be formed only from the above-mentioned long-afterglow orange-emitting phosphor, or may be formed from a small amount of other materials in order to adjust the emission color or afterglow time. It may also be formed from a mixture of phosphors.

The sulfide phosphor used in the cathode ray tube of the present invention can emit any emission color from orange close to red to orange close to yellow by selecting the amount of Cd in the matrix, the type of activator, and the amount of activation. Moreover, its coating properties are good and its brightness is high. Therefore, by combining the cathode ray tube of the present invention with the electron gun described above, a cathode ray tube having a luminescent color suitable for display use and excellent image quality (resolution, uniformity, etc.) was obtained.

The sulfide phosphor used in the present invention uses either copper or copper and gold as an activator and the second co-activator as a co-activator, and has the same base material. The afterglow time after excitation by electron beams, ultraviolet rays, etc. is stopped is several tens to hundreds of times longer than that of fluorescent materials.

Note that all values of afterglow time described in this specification are values when the current density of the stimulating electron beam emitted from the electron gun is 0.4 μA/cm ² .

In addition, the beam diameter at the fluorescent surface referred to in the present invention refers to the diameter of the luminescent spot emitted at the just-focus section when the cathode ray beam is irradiated onto the fluorescent surface, since the beam diameter of cathode rays cannot be directly measured. φ ₁₀ of the emission intensity distribution (10% of the peak brightness on the brightness distribution)
corresponds to the spot diameter (defined at the position).

The phosphor used in the present invention has a characteristic that conventional long-afterglow phosphors do not have, in that the afterglow time varies greatly depending on the current density of the stimulating electron beam, and generally, this tendency tends to change as the current density decreases. Afterglow time becomes longer.

The present invention will be explained in detail below.

As shown in FIG. 1, the structure of the cathode ray tube of the present invention is almost the same as that of a conventional monochromatic cathode ray tube such as a cathode ray tube for black and white television, except for the electron gun and fluorescent film components. That is, in the cathode ray tube of the present invention, an electron gun 3 is provided in a neck portion 2 of a funnel 1, and a fluorescent film 5 is formed on the entire surface of a face plate 4 facing the electron gun 3. Generally, fluorescent film 5
An aluminum vapor-deposited film 6 is provided on the back surface of the device to prevent charge-up during excitation. In the cathode ray tube configured in this manner, a phosphor film 5 made of a specific long afterglow green to yellowish green emitting phosphor and an electron gun 3 having a specific beam diameter and frame frequency are used.
It is characterized by consisting of.

The method for manufacturing the long-afterglow orange-emitting phosphor used in the present invention is described in detail in Japanese Patent Application Laid-Open No. 142970/1989, which was previously filed by the applicant. That is, the long-afterglow orange-emitting phosphor used in the present invention comprises phosphor raw materials (base raw material, activator raw material, first co-activator raw material, and second co-activator raw material). The required amount is weighed out and thoroughly mixed using a grinding mixer to obtain a phosphor raw material mixture, which is then filled into a heat-resistant container and heated to 0.5-7. It can be produced by firing for about an hour, washing the resulting fired product with water, drying, and passing it through a sieve.

The long afterglow orange-emitting phosphor used in the present invention obtained based on the manufacturing method described in JP-A-58-142970, etc. has a compositional formula of (Zn _1-x , Cdx)S.
(However, x is a number that satisfies the range 0.15≦x≦0.35)
Zinc cadmium sulfide represented by is used as a matrix, at least one of copper or gold is used as an activator, at least one of gallium or indium is used as a first co-activator, and one of chlorine, bromine, iodine, fluorine and aluminum is used as a base material. at least one kind is a second co-activator; the activator, the first co-activator and the second co-activator;
of the co-activator, respectively, with respect to the matrix,
10 ^-4 to 1% by weight, 10 ^-6 to 10 ^-1 % by weight and 5×
A phosphor containing 10 ^-6 to 5 x 10 ^-1 % by weight of sulfur (this phosphor also includes one containing 10 ^-5 to 8 x 10 ^-1 % by weight of sulfur based on the matrix). the above activator,
The amounts of the first coactivator and the second coactivator are 10 ^-3 to 6×, respectively, in terms of image quality and brightness of the cathode ray tube.
10 ^-1 wt%, 5 x 10 ^-5 to 5 x 10 ^-2 wt% and 5
More preferably, it is 10 ^-5 to ^{10 -1} % by weight.

The emission color of this phosphor varies from orange close to red to orange close to yellow depending on the amount of cadmium, the type of activator, and the amount of activation. When the amount of cadmium is increased, a longer wavelength emission color is exhibited, and generally when the amount of copper and gold, which are activators, is increased, a longer wavelength emission color is exhibited. In addition, afterglow characteristics (afterglow time, etc.) mainly depend on the type and amount of activation of the first co-activator and the type and amount of activation of the second co-activator. It's decided. Furthermore, the electron gun used in the present invention has a beam diameter at the fluorescent surface.
It emits cathode rays with a diameter of 0.05 to 0.4 mm and a frame frequency of 20 to 50 Hz.

FIGS. 2 and 3 illustrate the emission spectra of the phosphor used in the cathode ray tube of the present invention. FIG. 2 shows the emission spectrum of the phosphor used in the cathode ray tube of the present invention using gold as an activator.
The composition formula is (Zn _0.82 Cd _0.18 )S: Au, Ga, Al, Cl
(However, Au = 1.4 × 10 ^-1 weight%, Ga = 5 × 10 ^-3 weight%, Al = 6 × 10 ^-2 weight%, Cl = 5 × 10 ^-3 weight%
It is. ), and FIG. 3 shows the emission spectrum of the phosphor used in the cathode ray tube of the present invention, which uses copper as an activator, and whose composition formula is ( Zn _0.78 Cd _0.22 )S:
Cu, Ga, Al, (Cu=1.2×10 ^-2 wt%, Ga
= 1.5 x 10 ^-3 weight %, Al = 3 x 10 ^-2 weight %. ) is the emission spectrum of the orange-emitting hexagonal phosphor.

As shown in FIGS. 2 and 3, the phosphor used in the present invention exhibits good orange light emission.

FIG. 4 is a graph illustrating the afterglow characteristics of the phosphor used in the cathode ray tube of the present invention. In Figure 4, the curve has a compositional formula of (Zn _0.82 Cd _0.18 )S:Au,
Ga, Al, Cl (however, Au=1.4×10 ^- ₁ % by weight, Ga=
5×10 ^-3 weight%, Al=6×10 ^-2 weight%, Cl=5×
10 ^-3 % by weight. ) is the afterglow characteristic of the orange-emitting phosphor after electron beam excitation is stopped.

As is clear from FIG. 4, the phosphor used in the present invention exhibits an afterglow time of about 30 milliseconds, which is sufficient for display purposes.

Figure 5 is a CIE diagram showing the emission color of the cathode ray tube of the present invention.
A diagram showing chromaticity points in a color system. Point A is (Zn _0.82 Cd _0.18 )
S is the base material, and the amounts of Au, Ga, Al, and Cl activators are 1.4×10 ^-1 weight% and 5×10 ^-3 relative to the base material, respectively.
_Point B is ⁽ Zn ^0.78 Cd _0.22
A phosphor containing S as a matrix and containing Cu, Ga, and Al activators in amounts of 1.2 x 10 ^-2 weight %, 1.5 x 10 ^-3 weight %, and 3 x 10 ^-2 weight %, respectively, relative to the matrix. This is the chromaticity point when used. It can be seen from FIG. 5 that the orange-emitting phosphor of the present invention exhibits good orange color development with a single phosphor. Therefore, unlike the case where a mixed phosphor of a P27 phosphor and a P39 phosphor produces long-afterglow orange luminescence, the long-afterglow orange-emitting phosphor of the present invention has a luminescent color. No uneven coloring occurs.

The case where gallium is included is shown above as a representative example, but even when indium is used instead of gallium, a slight difference in afterglow time was observed as shown in the above-mentioned Japanese Patent Application Laid-Open No. 142970/1983. However, almost the same effect as in the case of gallium was obtained.

Further, since the phosphor used in the present invention has a matrix of zinc sulfide, the particle size can be easily obtained from several microns to more than ten microns depending on the manufacturing method. In addition, with conventional long-afterglow orange-emitting phosphors, the particle shape and particle size distribution are unfavorable for coating, making it difficult to obtain a good fluorescent film.However, the fluorescent material used in the present invention has an almost spherical shape. Therefore, a good fluorescent film can be obtained.

As described above, the cathode ray tube of the present invention can provide a good orange luminescent color. Furthermore, since the phosphor used itself emits high-intensity light and is capable of forming a good fluorescent film, it is possible to obtain higher-intensity light emission than in conventional cathode ray tubes.

Incidentally, a small amount of a conventionally known phosphor may be mixed with the phosphor used in the present invention to adjust the emission color and afterglow characteristics. Further, in the phosphor used in the present invention, a part of the first coactivator may be substituted with scandium. Further, the phosphor of the present invention may be further activated with an activator such as divalent europium, bismuth, or antimony. Further, in the phosphor of the present invention, part of the sulfur may be replaced with selenium in order to shift the emission wavelength to a somewhat longer wavelength side.

Additionally, pigments can be attached to or mixed with the phosphors used in the present invention to improve the contrast of the phosphors. Pigments that have an orange color that is almost the same as the luminescent color of the phosphor (lead, molybdenum orange, cadmium selenide pigments, etc.) and black pigments (iron oxide, tungsten, etc.) are used as the pigments to be attached. is used in an amount of 0.5 to 40 parts by weight per 100 parts by weight of the phosphor of the present invention.

The sulfide phosphor of the present invention can be subjected to any of the surface treatments and particle size selections used for conventionally known sulfide phosphors.

As described above, the cathode ray tube of the present invention exhibits high-intensity orange light emission due to a good fluorescent surface, and has extremely high industrial utility value.

Next, the present invention will be explained with reference to Examples.

Example 1 ZnS 750g CdS 250g HAuCl ₄・4H ₂ O 2.93g Ga (NO ₃ ) ₃・8H ₂ O 0.287g Al ₂ (SO ₄ ) ₃・18H ₂ O 7.40g These phosphor raw materials were prepared using a ball mill. After thorough mixing, appropriate amounts of sulfur and carbon were added and filled into a quartz crucible. After capping the quartz crucible,
The crucible was placed in an electric furnace and fired at a temperature of 950°C for 3 hours. During this firing, the inside of the crucible was in a carbon disulfide atmosphere. The fired product obtained after firing was taken out from the crucible, washed with water, dried, and passed through a sieve. In this way, the activation amounts of gold, gallium, aluminum, and chlorine were 1.4×10 ^-1 % by weight, 5×10 ^-3 % by weight of the zinc sulfide cadmium matrix, respectively.
A (Zn _0.82 Cd _0.18 )S:Au, Ga, Al, Cl phosphor with a concentration of 6×10 ⁻² and 5×10 ⁻³ weight % was obtained.

This phosphor had a median particle size distribution of 8 microns, and was a particle exhibiting a spherical morphology with a sharp particle size distribution. This phosphor was applied onto a face plate by a sedimentation method at a concentration of 4 mg/cm ² to form a phosphor film. This fluorescent film was smooth and good. Using this and an electron gun with a beam diameter of 0.2 mm and a frame frequency of 40 Hz, a cathode ray tube of the present invention as shown in FIG. 1 was obtained.

The emission spectrum of this cathode ray tube is shown in FIG. 2, and its afterglow time was about 30 milliseconds, as shown in FIG. 4, and a good display was obtained. The color of the emitted light is point A (x=
0.56, y=0.43).

This cathode ray tube has approximately twice the brightness of a conventional cathode ray tube that uses a mixed phosphor consisting of a P27 phosphor and a P39 phosphor.

Example 2 ZnS 700g CdS 300g CuSO ₄・5H ₂ O 0.472g Ga (NO ₃ ) ₃・8H ₂ O 0.086g Al ₂ (SO ₄ ) ₃・18H ₂ O 3.70g Conducted using these phosphor raw materials In the same manner as in Example 1, the activation amounts of copper, gallium, and aluminum are 1.2 x 10 ^-2 weight %, 1.5 x 10 ^-3 weight %, and 3 x 10 ^-2 weight % of the zinc sulfide cadmium matrix, respectively (Zn _0.78 Cd _0.22 ) S:Cu, Ga, Al phosphor was obtained. This phosphor had a median particle size distribution of 9 microns, and was a particle exhibiting a spherical morphology with a sharp particle size distribution. This phosphor was applied onto a face plate by a precipitation coating method to form a phosphor film at a concentration of 5 mg/cm ² . This fluorescent film was smooth and good. With this and an electron gun with a beam diameter of 0.3 mm and a frame frequency of 45 Hz,
A cathode ray tube of the present invention shown in FIG. 1 was obtained.

This cathode ray tube had an afterglow time of about 20 milliseconds after the electron beam excitation stopped, and a good display was obtained. The color of the emitted light is point B (x=0.56,
y=0.44).

This cathode ray tube has approximately twice the brightness of a conventional cathode ray tube that uses a mixed phosphor consisting of a P27 phosphor and a P39 phosphor.

Example 3 ZnS 623g CdS 377g CuSO ₄・5H ₂ O 0.590g Ga(NO ₃ ) ₃・8H ₂ O 0.172g NaCl 0.823g After thoroughly mixing these phosphor raw materials using a ball mill, sulfur and carbon An appropriate amount of was added and filled into a quartz crucible. After capping the quartz crucible,
The crucible was placed in an electric furnace and fired at a temperature of 950°C for 3 hours. During this firing, the inside of the crucible was in a carbon disulfide atmosphere. The fired product obtained after firing was taken out from the crucible, washed with water, dried, and passed through a sieve. In this way, the activation amounts of copper, gallium, and chlorine are respectively adjusted to the zinc cadmium sulfide matrix.
1.5×10 ^-2 wt%, 3×10 ^-3 wt% and 5×10 ^-2
A phosphor of (Zn _0.75 Cd _0.25 ) S:Cu, Ga, Cl in weight % was obtained.

This phosphor had a median particle size distribution of 7 microns, and was a particle exhibiting a spherical morphology with a sharp particle size distribution. This phosphor was applied onto a face plate by a sedimentation method at a concentration of 4 mg/cm ² to form a phosphor film. This fluorescent film was smooth and good. Using this and an electron gun with a beam diameter of 0.3 mm and a frame frequency of 40 Hz, a cathode ray tube of the present invention as shown in FIG. 1 was obtained.

Its afterglow time was approximately 25 milliseconds, and a good display was obtained.

This cathode ray tube has improved brightness by about 1.8 times compared to the conventional cathode ray tube that uses a mixed phosphor consisting of a P27 phosphor and a P39 phosphor.

Example 4 ZnS 750g CdS 250g HAuCl・4H ₂ O 2.93g In(NO ₃ ) ₃・3H ₂ O 1.236g Al ₂ (SO ₄ ) ₃・18H ₂ O 7.40g These phosphor raw materials were prepared using a ball mill. After thorough mixing, appropriate amounts of sulfur and carbon were added and filled into a quartz crucible. After capping the quartz crucible,
The crucible was placed in an electric furnace and fired at a temperature of 950°C for 3 hours. During this firing, the inside of the crucible was in a carbon disulfide atmosphere. The fired product obtained after firing was taken out from the crucible, washed with water, dried, and passed through a sieve. In this way, the activation amounts of gold, indium, and aluminum are respectively 1.4×10 ^-1 wt%, 3×10 ^-2 wt%, and 6×10 ^-2 wt% of the zinc cadmium sulfide matrix (Zn _0.82 Cd _0.18 ) S: Au,
In, Al phosphors were obtained.

This phosphor had a median particle size distribution of 7 microns, and was a particle exhibiting a spherical morphology with a sharp particle size distribution. This phosphor was applied onto a face plate by a sedimentation method at a concentration of 4 mg/cm ² to form a phosphor film. This fluorescent film was smooth and good. Using this and an electron gun with a beam diameter of 0.2 mm and a frame frequency of 40 Hz, a cathode ray tube of the present invention as shown in FIG. 1 was obtained.

The emission spectrum of this cathode ray tube is shown in Figure 2, and its afterglow time was about 40 milliseconds, providing a good display. The color of the emitted light is shown at point A (x=0.56, y=0.43) in FIG.

This cathode ray tube has improved brightness by about 1.5 times compared to the conventional cathode ray tube that uses a mixed phosphor consisting of a P27 phosphor and an S39 phosphor.

Example 5 ZnS 750g CdS 250g CuSO ₄・5H ₂ O 0.590g Ga(NO ₃ ) ₃・8H ₂ O 0.287g NaI 0.575g After thoroughly mixing these phosphor raw materials using a ball mill, sulfur and carbon An appropriate amount of was added and filled into a quartz crucible. After capping the quartz crucible,
The crucible was placed in an electric furnace and fired at a temperature of 950°C for 3 hours. During this firing, the inside of the crucible was in a carbon disulfide atmosphere. The fired product obtained after firing was taken out from the crucible, washed with water, dried, and passed through a sieve. In this way, the copper, gallium and iodine activators are respectively added to the zinc cadmium sulfide matrix.
1.5×10 ^-2 wt%, 5×10 ^-3 wt% and 1×10 ^-2
A phosphor of (Zn _0.82 Cd _0.18 )S:Cu,Ga,I having a weight % of (Zn 0.82 Cd 0.18 ) was obtained.

This phosphor had a median particle size distribution of 7 microns, and was a particle exhibiting a spherical morphology with a sharp particle size distribution. This phosphor was applied onto a face plate by a sedimentation method at a concentration of 4 mg/cm ² to form a phosphor film. This fluorescent film was smooth and good. Using this and an electron gun with a beam diameter of 0.3 mm and a frame frequency of 40 Hz, a cathode ray tube of the present invention as shown in FIG. 1 was obtained.

Its afterglow time was approximately 25 milliseconds, and a good display was obtained.

This cathode ray tube has improved brightness by about 1.5 times compared to the conventional cathode ray tube that uses a mixed phosphor consisting of P27 and P39 phosphors.

Example 6 ZnS 700g CdS 300g CuSO _{4.5H 2} O 0.590g Ga(NO ₃ ) _{3.8H 2} O 0.287g NaBr 0.387g NaF 0.221g After thoroughly mixing these phosphor raw materials using a ball mill, Appropriate amounts of sulfur and carbon were added and filled into a quartz crucible. After capping the quartz crucible,
The crucible was placed in an electric furnace and fired at a temperature of 950°C for 3 hours. During this firing, the inside of the crucible was in a carbon disulfide atmosphere. The fired product obtained after firing was taken out from the crucible, washed with water, dried, and passed through a sieve. In this way, the activation amounts of copper, gallium, bromine, and fluorine are 1.5×10 ^-2 weight%, 5×10 ^-3 weight%, and 3×10 ^-3 of the zinc sulfide cadmium matrix, respectively.
% by weight and 1×10 ^-3 % by weight (Zn _0.78
Cd _0.22 ) S:Cu, Ga, Br, F phosphor was obtained.

This phosphor had a median particle size distribution of 9 microns, and was a particle exhibiting a spherical morphology with a sharp particle size distribution. This phosphor was applied onto a face plate by a sedimentation method at a concentration of 4 mg/cm ² to form a phosphor film. This fluorescent film was smooth and good. Using this and an electron gun with a beam diameter of 0.2 mm and a frame frequency of 40 Hz, a cathode ray tube of the present invention as shown in FIG. 1 was obtained.

Its afterglow time was approximately 26 milliseconds, and a good display was obtained.

This cathode ray tube has improved brightness by approximately 1.6 times compared to a conventional cathode ray tube that uses a mixed phosphor consisting of a P27 phosphor and a P39 phosphor.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the cathode ray tube of the present invention, FIGS. 2 and 3 are emission spectra of the phosphor used in the cathode ray tube of the present invention, and FIG. 4 is a sectional view of the phosphor used in the cathode ray tube of the present invention. A graph illustrating the afterglow characteristics of the body, FIG. 5 shows the emission color of the cathode ray tube of the present invention.
It is a diagram showing chromaticity points of the CIE color system. DESCRIPTION OF SYMBOLS 1... Funnel, 2... Network part, 3... Electron gun, 4... Face plate, 5... Fluorescent film, 6
...Aluminum vapor deposited film.

Claims (1)

[Claims] 1. An electron gun that emits cathode rays with a beam diameter of 0.05 to 0.4 mm at the fluorescent surface and a frame frequency of 20 to 50 Hz, and a face plate opposite to the electron gun. The composition formula is (Zn _1-x , Cdx)S
(However, x is a number that satisfies the range 0.15≦x≦0.35)
Zinc cadmium sulfide represented by the matrix, at least one of copper or gold as an activator, at least one of gallium or indium as a first co-activator, and at least one of chlorine, bromine, iodine, fluorine and aluminum. seeds as a second co-activator,
The amounts of the activator, the first co-activator, and the second co-activator are 10 ^-4 to 1% by weight, 10 ^-6 to 10 ^-1 % by weight, and 5×, respectively, based on the base material. 10 ^-6 ~5×
1. A cathode ray tube for a monochrome display, characterized in that it is formed with a phosphor film containing 10 ^-1 % by weight of a long-afterglow orange-emitting phosphor as a main component. 2. The electron gun has a beam diameter of 0.07 to 0.3 mm,
A cathode ray tube for monochrome display according to claim 1, characterized in that the frame frequency is 25 to 40 Hz. 3. The activation amount of the activator, the first co-activator, and the second co-activator is 10 ^-3 to 6 x 10 ^-1 % by weight, and 5 x 10 ^-5 to 5 x 10 ^-2 by weight, respectively. Weight% and 5×10 ^-5 ~
A cathode ray tube for monochrome display according to claim 1 or 2, characterized in that the content is 10 ^-1 % by weight. 4. Claims 1 to 3, wherein the fluorescent film contains a pigment having an orange or black body color in an amount of 0.5 to 40% by weight based on the long afterglow orange-emitting phosphor. A cathode ray tube for monochrome display as described in any of the following paragraphs.