JPS6212952B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a green-emitting fluorescent film for cathode ray tubes,
In particular, the present invention relates to a green-emitting fluorescent film for cathode ray tubes that emits light with high brightness and has low current saturation.

ZnS/Cu, ZnCdS/Cu or ZnS/
Cu, Au, and Al phosphors are used. The green-emitting phosphor that uses zinc sulfide as a matrix has the advantage that it has high efficiency among phosphors that emit green light when excited by an electron beam and can provide a bright screen, but on the other hand, it exhibits a current saturation phenomenon. It also has the disadvantage of The current saturation phenomenon refers to a phenomenon in which when a phosphor is excited with an electron beam at a high current density, an increase in brightness corresponding to an increase in current density is no longer observed compared to when the phosphor is excited at a low current density. Therefore, even if the green-emitting zinc sulfide-based phosphor is excited by an electron beam with a high current density above a certain value, it becomes difficult to obtain a screen with higher brightness. On the other hand, among the other two-color emitting phosphors that make up the phosphor screen of color television cathode ray tubes, for example, Y ₂ O ₂ S/Eu phosphor shows almost no current saturation phenomenon, and ZnS/Eu phosphor shows almost no current saturation phenomenon.
Ag phosphors also do not exhibit the same current saturation phenomenon as the green-emitting phosphors. Therefore, at high current density,
This will disrupt the balance of light emission intensity of the three colors for color reproduction. Therefore, for example, for a white screen that requires high current density, when trying to obtain a white screen with a desired color temperature, the intensity ratio of the red component becomes stronger than the green component, and as a result, only a white screen with a lower color temperature is obtained. I'll lose it.

The object of the present invention is to solve the above-mentioned drawbacks of the conventional green-emitting phosphor film for color televisions, and to provide a green-emitting phosphor film for color televisions which is further improved. That is, this invention is a Cu activator with a high concentration of Cu activator.
Activated zinc sulfide green emitting phosphor and Gd ₂ O ₂ S/Tb phosphor or Y ₂ O ₂ S/Tb with specified Tb activator concentration
The present invention provides a phosphor film made by mixing at least one of the phosphors with a Tb-activated green-emitting rare earth phosphor. That is, this invention uses Cu as an activator.
A green-emitting zinc sulfide-based phosphor that is at least one of a copper-based activated zinc sulfide green-emitting phosphor containing 0.01 to 0.10% by weight of Cu or a copper-based activated zinc sulfide green-emitting phosphor containing 0.005 to 0.05% by weight of Cu. and Y ₂ O ₂ S/ containing at least 3.0% by weight of Tb as an activator.
Contains Tb phosphor or at least 2.0% by weight of Tb
at least one of the Gd ₂ O ₂ S/Tb phosphors, a Tb-activated green-emitting phosphor, and the weight ratio of the zinc sulfide-based phosphor and the Tb-activated green-emitting phosphor is 1:9 to 1:9. A green-emitting fluorescent film for a cathode ray tube has a ratio of 9:1. Such a configuration improves the current characteristics of the phosphor film and provides the effect of significantly improving the brightness of the phosphor film.

Figure 1 shows the excitation spectra and emission spectra of various zinc sulfide-based green-emitting phosphors. In the figure, the vertical axis represents relative energy as an arbitrary value, and the horizontal axis represents wavelength.
Curves 11 and 14 represent 0.01% by weight.
ZnS/Cu activated with Cu, ~0.02 wt% Al,
For Al phosphor, curves 12 and 15 show 0.01 wt%
For ZnS/Cu, Au, Al phosphors activated with Cu, 0.02 wt% Au, and 0.015 wt% Al, curves 13 and 16 were activated with 0.008 wt% Cu, 0.01 wt% Al. These are the excitation and emission spectra of ZnCdS/Cu and Al phosphors, respectively. It goes without saying that each phosphor with zinc sulfide or cadmium sulfide as a matrix emits green light when excited by an electron beam, but as can be seen from Figure 1, it emits ultraviolet light with an absorption edge extending to the blue region of approximately 450 nm. Even when excited, it emits green light with an emission peak between about 530 nm and about 540 nm.

Figure 2 also shows that 6.8% by weight when excited with an electron beam.
The emission spectrum of Y ₂ O ₂ S/Tb phosphor activated with Tb is shown. In the figure, the vertical axis represents relative energy as an arbitrary value, and the horizontal axis represents wavelength in nm. As is clear from the figure, the emission spectrum of Y ₂ O ₂ S/Tb phosphor due to electron beam excitation is not limited to only green light, but also e.g.
It can be seen that blue light and ultraviolet light having an emission peak at 416 nm or about 383 nm are included. Therefore, the zinc sulfide-based green light-emitting phosphor and the Y ₂ O ₂ S/
When a mixed film of Tb phosphors is formed and excited with an electron beam, not only the green light generated from each of the two phosphors, but also the blue light and ultraviolet light generated by the Y ₂ O ₂ S/Tb are transferred to the sulfide. It is expected that the zinc-based green light-emitting phosphor will absorb the light and convert it into green light. The above effect is called a double excitation effect.

FIG. 3 shows the electron beam excitation emission spectrum of the Gd ₂ O ₂ S/Tb phosphor activated with 2.0% by weight of Tb. As is clear from the figure, this phosphor is also Y ₂ O ₂ S/
Like Tb, it exhibits an emission spectrum in the blue and ultraviolet regions, and is expected to have the same double excitation effect as described above.

The mixed fluorescent film exhibiting the double excitation effect will be described in detail below. Here, from among the possible combinations of the zinc sulfide-based green-emitting phosphor and the rare earth-based green-emitting phosphor, the combinations of ZnS/Cu, Al and Y ₂ O ₂ S/Tb will be selected and explained as representative combinations. .

First, FIG. 4 shows the relative brightness when the ZnS/Cu and Al phosphors are excited to emit light with electron beams and ultraviolet rays when the concentration of the Cu activator is varied. In the figure, the vertical axis represents the relative brightness as an arbitrary value, the horizontal axis represents the Cu activator concentration in weight%, and curve 17 is 25kV, 1μ
Due to electron beam excitation at A/cm ² , curve 18 is
Shows light emission by excitation of 3650nm ultraviolet light. In the case of electron beam excitation, the Cu concentration at which the emission brightness is maximum is:
It is found that the concentration is 0.009% by weight relative to the ZnS matrix, but in the case of ultraviolet excitation, the concentration shifts to a higher concentration and reaches a maximum at 0.06% by weight. Therefore, as a mixed film with a rare earth phosphor, taking into account the double excitation effect, it is recommended to use ZnS/Cu or Al activated with a higher concentration of Cu than the conventional 0.009% by weight to achieve good brightness. It is a tube that allows you to

Figure 5 shows Y ₂ O ₂ S activated with 6.0 wt% Tb.
ZnS/with various Cu concentrations compared to the phosphor
This graph shows the change in luminance of the phosphor film when Cu and Al phosphors are mixed at a ratio of 1:1 to form a phosphor film and emitted using an electron beam of 25 kV and 1 μA/cm ² . In the figure, the vertical axis represents the relative brightness of the fluorescent film, and the horizontal axis represents the Cu concentration of ZnS/Cu and Al. As can be seen from the curve, the concentration reaches its maximum when Cu is 0.045% by weight, becomes almost the same at 0.1% by weight as at 0.01% by weight, and gradually decreases at higher concentrations. In this way, with ZnS/Cu and Al alone, Cu
The brightness was maximized at 0.009% by weight, but the mixed film had a higher concentration, i.e. from 0.01% to 0.1% by weight.
It can be seen that particularly preferably 0.03% by weight to 0.07% by weight results in higher brightness. It can be understood from this that a double excitation effect is brought about.

Next, increasing the concentration of Cu is effective not only in terms of brightness but also in improving current characteristics. FIG. 6 is a diagram showing current characteristics when ZnS/Cu phosphor single films with different Cu concentrations are caused to emit light with an electron beam. In the figure, the vertical axis represents the relative brightness, and the horizontal axis represents the current density of the 25 kV electron beam. Curve 19 is for the 0.05 wt% Cu-activated ZnS/Cu phosphor single film used in this invention, and curve 20 is for the non-specified 0.009 wt% Cu-activated ZnS/Cu phosphor single film.
The current characteristics of Cu-activated ZnS/Cu phosphor single film are shown. From the figure, the high-concentration Cu-activated ZnS/Cu phosphor single film specified for use in this invention has lower brightness than the low-concentration Cu-activated ZnS/Cu phosphor single film, but its current characteristics is good,
It is observed that the brightness difference decreases as the current density increases.

Taking all the above into account, we formed a 1:1 combination of ZnS/Cu phosphor activated with Cu at a higher concentration than generally used and Y ₂ O ₂ S/Tb phosphor. The current characteristics of each green-emitting mixed fluorescent film of the present invention are shown in FIG. 7 in comparison with a ZnS/Cu single film. In the figure, the vertical axis represents the relative brightness, and the horizontal axis represents the current density of the 25 kV electron beam. Curve 21 shows ZnS/Cu phosphor activated with 0.06 wt% Cu and 6 wt%
Curve 22 is a mixed phosphor film of Y ₂ O ₂ S/Tb phosphor activated with Tb of
Cu alone film, curve 23, ZnS/Cu activated with 0.009 wt% Cu, Al and 6 wt% Tb
3 is a curve showing the current characteristics of a comparative example mixed fluorescent film of Y ₂ O ₂ S/Tb.

For example, Y ₂ O ₂ S/Tb phosphor and ZnS/
The mixed phosphor film formed by Cu phosphor is ZnS/
Although the brightness is lower at low current densities than a single Cu phosphor film, it is seen that it has excellent linearity with respect to current density and reverses to high brightness at high current densities. In addition, in the mixed fluorescent film, it is recognized that those using activated ZnS/Cu and Al using higher concentrations of Cu are superior in terms of linearity to current density and relative brightness.

As described above, the mixed phosphor film of the present invention has excellent current characteristics and exhibits high film brightness especially at high current densities. It is therefore possible to brighten color television white screens which require high current densities. As a result of more faithfully reproducing the signal from the electron beam sent from the electron gun, it is also possible to obtain a white screen with a more desired color temperature than in the past.
In addition, the current characteristics are improved even at low current densities to reproduce black screens with more faithful black, and the overall screen has been improved to make white areas whiter and black areas blacker, resulting in a screen with better contrast. I can do it.

The effects of the fluorescent film of this invention described above are as follows:
Y ₂ O ₂ S/Tb phosphor and ZnS/Cu phosphor or ZnS/
Obtained for each mixed phosphor film of Cu and Al phosphors,
A mutual compounding ratio of 1:9 to 9:1 is good and does not change. In other words, if the amount of Y ₂ O ₂ S/Tb mixed is less than 10% of the total mixed film, only a slight improvement effect on current characteristics can be obtained, and even at high current density, the brightness is about the same as that of a conventional zinc sulfide-based single fluorescent film. It will only be the same. On the other hand, when the amount of Y ₂ O ₂ S/Tb exceeds 90%, the current characteristics are greatly improved, but the ratio of Y ₂ O ₂ S/Tb, which has low luminous efficiency, becomes too large compared to ZnS/Cu. As a result, the luminance level of the mixed phosphor film as a whole is lowered, and even at high current densities, only a luminance substantially equal to or lower than the conventional one can be obtained.

In addition to Y ₂ O ₂ S/Tb, Gd ₂ O ₂ S/Tb or
In addition to ZnS/Cu, ZnS/Cu, Al, ZnS/Cu, Au,
A similar effect can be obtained by using Al or ZnCdS/Cu. At that time, the activator concentration was ZnS/Cu,
For Au and Al, Cu is 0.01 to 0.10% by weight, Au and Al are respectively 0.01 to 0.2% by weight, and 0.005 to 0.3% by weight, more preferably Cu is 0.03 to 0.07% by weight.
Au and Al are 0.03 to 0.15% by weight and 0.02 to 0.02% by weight, respectively.
0.15% by weight, and in ZnCdS/Cu, Cu is 0.005% by weight.
It has been found that the brightness and current characteristics of the formed phosphor film are improved in the range of 0.05% to 0.05% by weight, more preferably 0.015% to 0.04% by weight. Since the rare earth phosphor is used as a green-emitting phosphor, Tb is 3% by weight in Y ₂ O ₂ S/Tb considering both luminance and emission color.
or more, up to 11% by weight, and for Gd ₂ O ₂ S/Tb, the amount of Tb is
It is desirable that the content be 2.0% by weight or more and up to 6% by weight.

Other embodiments of the invention will be described below. In each example, red, blue, and green phosphor slurries were applied by a conventional method to form a color cathode ray tube phosphor screen equipped with a phosphor film for each color. For convenience, the red-emitting phosphor and the blue-emitting phosphor are 5% by weight Eu-activated.
Y ₂ O ₂ S/Eu phosphor and 0.02 wt% Ag activated ZnS/
Ag phosphor is used. Regarding the green-emitting phosphor film, the current characteristic curve is shown especially when it is excited and emitted by a 25 kV electron beam. In each figure, the vertical axis shows the arbitrary value relative brightness of the green-emitting fluorescent film, and the horizontal axis shows the current density μA/cm ² of the electron beam. The phosphor screen of any of the examples has the same point that when the entire screen is illuminated, a bright high-contrast screen of white and black is obtained.

Example 1 In this example, the green-emitting fluorescent film contains 0.04% by weight of Cu,
Activated with 0.03 wt% Au, 0.02 wt% Al
ZnS/Cu, Au, Al phosphor and Y ₂ O ₂ S/Tb phosphor activated with 7 wt% Tb were mixed at a weight ratio of 6:4, and this was mixed using the slurry method described above. It is coated to form a mixed fluorescent film.

The current characteristics of the green-emitting phosphor film of the phosphor screen in this example during electron beam excitation and emission are as shown by curve 24 in FIG. Curve 25 shows ZnS activated with 0.009 wt% Cu, 0.008 wt% Au, and 0.005 wt% Al.
Indicates the characteristics of Cu, Au, and Al phosphor single films,
Curve 26 is 0.005 wt% Cu and 0.018 wt% Au
and ZnS activated with 0.007 wt% Al
Current characteristics of a comparative fluorescent film formed by mixing Cu, Au, Al phosphors and Y ₂ O ₂ S/Tb phosphors activated with 7% Tb at a weight ratio of 6:4. . As can be seen from the figure, the green-emitting phosphor film of the present invention has improved current saturation characteristics compared to a phosphor-only film.
The brightness when excited with an electron beam of 3 μA/cm ² is higher than that of conventional
It has reached 113%. Moreover, when compared to Comparative Example Mixed Film 26 with a low Cu concentration, it is 106%. Also, when the entire screen is illuminated, a bright high-contrast screen of white and black can be obtained.

Example 2 In this example, the green-emitting fluorescent film is made of 0.05% by weight of Cu.
ZnS/Cu activated with ZnS/Cu and Gd ₂ O ₂ S/Tb activated with 5 wt% Tb were mixed at a weight ratio of 2:1, and this was applied using the slurry method described above. This is a mixed fluorescent film.

Curve 27 in FIG. 9 shows current characteristics during electron beam excitation and emission of the green-emitting phosphor film of this example phosphor screen.
Curve 28 was activated with 0.009% by weight of Cu.
Curve 29 for the ZnS/Cu phosphor alone film and the ZnS/Cu phosphor activated with 0.009 wt% Cu and 5 wt%
These are curves representing the current characteristics of a comparative phosphor film formed by mixing both Gd ₂ O ₂ S/Tb phosphors activated with Tb at a weight ratio of 2:1.
As can be seen from the figure, the green-emitting fluorescent film of the present invention has improved current saturation characteristics compared to the conventional one, and the luminance of the fluorescent film when excited with an electron beam of 3 μA/cm ² at high current density is lower than that of ZnS. /Cu single film 28-109
%, and reached 102% of Comparative Example Mixed Film 29.

Example 3 In this example, the green-emitting phosphor film contains 0.03% by weight of Cu.
ZnCdS/Cu phosphor activated with 4.5 wt% Tb
The activated Y ₂ O ₂ S/Tb phosphor was mixed at a weight ratio of 2:8, and this was coated using the slurry method described above to form a mixed phosphor film.

Curve 30 in FIG. 10 shows current characteristics during electron beam excitation and emission of the green-emitting phosphor film of the phosphor screen of this example. Curve 31 was activated with 0.009 wt% Cu
Curve 32 represents the characteristics of ZnCdS/Cu phosphor single film, and curve 32 shows the characteristics of ZnCdS/Cu phosphor film activated with 0.009% by weight of Cu.
The characteristics of a comparative fluorescent film formed by mixing Cu and Y ₂ O ₂ S/Tb activated with 2% by weight of Tb at a weight ratio of 2:8 are shown. As can be seen from the figure, the green-emitting fluorescent film of the present invention has improved current saturation characteristics. In particular, the brightness of the fluorescent film when excited with a high current density electron beam of 3 μA/cm ² is 115% that of a single film, or It reached 106% of the comparative example mixed membrane.

Example 4 In this example, the green-emitting fluorescent film contains 0.07% by weight of
ZnS/Cu, Au, Al phosphor activated with Cu, 0.05 wt% Au, 0.03 wt% Al and 4 wt% Tb
The phosphor is made of a mixture of activated Gd ₂ O ₂ S/Tb phosphors at a weight ratio of 7:3.

Curve 33 in FIG. 8 shows current characteristics during electron beam excitation and emission of the green-emitting phosphor film of the phosphor screen of this example. This mixed film has improved current characteristics, and especially when excited with an electron beam at a high current density of 3 μA/cm ² , the luminance of the fluorescent film is as shown in curve 25 for the ZnS/Cu, Au, and Al phosphor single film in Figure 8. It was 109% of the total. Also, ZnS/Cu, Au, Al phosphor activated with 0.008 wt% Cu, 0.007 wt% Au, 0.004 wt% Al, and Gd ₂ O ₂ S/Cu, Au, Al phosphor activated with 4 wt% Tb. 7 of Tb phosphor:
3μ for the comparative example fluorescent film mixed at a weight ratio of 3μ
The brightness in A/cm ² is 103%.

Example 5 In this example, the green-emitting phosphor film contains 0.04% by weight of Cu.
ZnCdS/Cu phosphor activated with
It is formed by mixing Gd ₂ O ₂ S/Tb phosphors activated with Tb at a weight ratio of 1:1 and applying the mixture using a slurry method.

Curve 34 in FIG. 10 shows current characteristics during electron beam excitation and emission of the green-emitting phosphor film of the phosphor screen of this example. This mixed phosphor film has improved current characteristics, and in particular, when excited with an electron beam at a high current density of 3 μA/cm ² , the luminance is 110
% is shown. Also activated with 0.009 wt% Cu
Compared to curve 32 for a 1:1 comparative mixed film of ZnCdS/Cu phosphor and Gd ₂ O ₂ S/Tb phosphor activated with 2 wt% Tb, this mixed film
The brightness in A/cm ² is 102%.

Example 6 A slurry was formed in which a ZnS/Cu phosphor activated with 0.06% by weight of Cu and a Y ₂ O ₂ S/Tb phosphor activated with 6% by weight of Tb were mixed in a ratio of 8.5:1.5. Curve 3 in Figure 11 shows the current characteristics related to the green-emitting fluorescent film.
5. Curve 36 is for ZnS/Cu single film activated with 0.01 wt% Cu, and curve 37 is for ZnS/Cu activated with 0.009 wt% Cu and Y ₂ O ₂ activated with 6 wt% Tb. The current characteristics of a comparative example mixed film in which S/Tb was mixed at a ratio of 8.5:1.5 are shown. The current characteristics of the Example mixed film of this example are improved, and the brightness is low in the low current density region, but at a high current density of 3 μA/cm ² , the luminance is 107% that of the conventional single film, and 103% compared to the Comparative Example mixed film. It shows the value in %.

Example 7 Current of a film in which ZnS/Cu phosphor activated with 0.06 wt% Cu and Y ₂ O ₂ S/Tb phosphor activated with 6 wt% Tb were mixed in a ratio of 1.5:8.5 The characteristics are shown in curve 38 in FIG. Also, curve 39 is 0.01% by weight.
Curve 40 of ZnS/Cu single film activated with Cu
shows the current characteristics of a comparative example mixed film in which ZnS/Cu activated with 0.009% by weight of Cu and Y ₂ O ₂ S/Tb activated with 6% by weight of Tb were mixed in a ratio of 1.5:8.5. The mixed film according to the present invention has improved current characteristics, and at a high current density of 3 μA/cm ^{2 ,} the current characteristics are 103% of the conventional single film and 100.5% of the comparative mixed film.

[Brief explanation of the drawing]

Figure 1 shows the excitation and emission spectra of various zinc sulfide-based green-emitting phosphors, Figure 2 shows the electron beam excitation emission spectra of the Y ₂ O ₂ S/Tb phosphor used in this invention, and Figure 3 used for this invention
Figure 4 shows the electron beam excitation emission spectrum of the Gd ₂ O ₂ S/Tb phosphor.
The figure shows the phosphor film of the present invention. Figure 6 shows the relationship between the Cu concentration of the ZnS/Cu phosphor mixed with the Y ₂ O ₂ S/Tb phosphor and the relative luminance of the mixed film. The current saturation characteristics of the ZnS/Cu phosphor used in
7 to 12 are diagrams showing the current saturation characteristics of the conventional green-emitting fluorescent film and the present invention, respectively.

Claims (1)

[Claims] 1 Copper-based activated zinc sulfide green phosphor containing copper or copper or gold as the main activator and 0.01 to 0.10% by weight of copper;
Or use copper as the main activator and add 0.005 to 0.05
At least one of the green-emitting zinc sulfide-based phosphors of the copper-based activated zinc sulfide cadmium green-emitting phosphor containing 3.0 to 3.0% by weight of terbium as the activator.
Terbium-activated yttrium oxysulfide green emitting phosphor containing 11.0% by weight, or 2.0 to 6.0% terbium
at least one of the terbium-activated gadolinium oxysulfide green-emitting phosphor containing terbium-activated green-emitting phosphor, and the weight ratio of the zinc sulfide-based phosphor and the terbium-activated green-emitting phosphor is A green-emitting fluorescent film for a cathode ray tube, characterized in that it has a ratio of 1:9 to 9:1.