JPS6359502B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluorescent surface of a cathode ray tube.

A useful means of increasing the image contrast of the fluorescent surface of a cathode ray tube is to reduce the light transmittance of the face plate glass of the fluorescent surface. This principle will be explained in detail with reference to FIG.

FIG. 1 is a cross-sectional model of the fluorescent surface of a color cathode ray tube. Reference numeral 1 denotes a face plate glass, and on its inner surface, a group of three-color phosphor elements 2 of red (R), green (G), and blue (B) are provided. Now, the intensity of the external light incident on the face plate glass 1 of the color cathode ray tube configured in this way is (E ₀ ), and after being reflected by the fluorescent surface, it comes out again to the outside of the face plate glass 1. The intensity of the reflected light is (E ₁ ), the light transmittance of the face plate glass 1 is (T), and the reflectance of the three-color phosphor element group 2 of red (R), green (G, and blue) is ( Rp), the intensity of light emission from the phosphor element group is (F ₀ ), and the output of the phosphor surface coming out of the face plate glass 1 is (F ₁ ), then E ₁ = E ₀・Rp・T ² ...() F ₁ = F ₀・T ...() becomes. Also, _the contrast C can be defined as C=E ₁ + _{F 1 /} E ₁ . Strictly speaking, factors such as reflection of external light on the surface of the face plate glass 1, multiple reflections within the face plate glass 1, and halation due to scattered electrons must also be introduced, but here these effects will be considered. I ignored it as it was small enough. It is clear from equation () that in order to improve the contrast of the cathode ray tube image, it is sufficient to lower the light transmittance (T) of the face plate glass 1. Conventionally, the glass used as face plate glass 1 for cathode ray tubes is generally classified into clear glass with a visible light transmittance of 75% or more, gray glass with a light transmittance of 60 to 75%, and taint glass with a light transmittance of 60% or less. The second
Figure a shows the typical spectral transmittance curves for clear galan, e for gray glass, and c for tainted glass. This is shown together with the spectrum.

On the other hand, as is clear from Fig. 2 and equation (), the light output of the fluorescent surface, that is, the brightness of the fluorescent surface, is different from the contrast as the light transmittance (T) of the face plate glass 1 becomes lower. It gets lower. In other words, contrast performance and brightness performance of images are difficult to reconcile as far as the light transmittance (T) of the face plate glass 1 is concerned, and it depends on which performance is more important.
A selection of types was made.

As a means to solve this dilemma regarding brightness performance and contrast performance and to improve both performances, a fluorescent surface was used instead of the conventional face plate glass, which has almost flat light transmittance in the visible range, as shown in Figure 2. It has been proposed to selectively provide the face plate glass 1 with light absorbing properties in the wavelength region between the valleys of the emission spectra of the three-color phosphor elements, that is, in the region of low emission energy. Figure 3 shows the spectral transmittance curve of face plate glass 1, which has been proposed as a material that almost satisfies these _purposes . It was formed by adding 0.5% by weight of O ₃ ). (Hereinafter referred to as neodymium-containing glass.) Due to the unique characteristics of neodymium oxide (Nd ₂ O ₃ ), this neodymium-containing glass has a steep main absorption band with a peak at about 580 nm and a sub-absorption band with a peak at about 530 nm. has. These absorption bands are very steep, so even though neodymium-containing glass has a high light transmittance that is almost as high as conventional clear glass in areas other than these absorption bands, the average light transmission throughout the visible range is low. The ratio is almost equivalent to that of gray glass, and it contributes to improving image contrast without impairing the brightness characteristics of the fluorescent surface.

FIG. 4 shows the spectral transmittance curve d of such neodymium-containing glass together with the spectral transmittance curve a of conventional clear glass. (The emission spectrum of the red (R), green (G), and blue (B) three-color phosphor elements of the color cathode ray tube is also shown at the same time.) When such neodymium-containing glass is used as face plate glass, the fluorescence Although the brightness and contrast characteristics of the surface are greatly improved as described above, the color of the fluorescent surface is significantly different from that of conventional cathode ray tubes, which has the disadvantage that it tends to give a strange appearance to the viewer.
The body color of this fluorescent surface will be explained in more detail with reference to FIG. The points in Figure 5 ABC are plotted on the CIE chromaticity diagram of the chromaticity points of a typical type of white extraneous light when viewing a television set at home, etc., and point A is the standard light source. This is the chromaticity point of a certain A light source, and it shows a value that is almost close to the chromaticity point of light from an incandescent lamp used at home. Point B shows an example of the chromaticity point of light from a white fluorescent lamp used at home. Point C is the chromaticity point of light source C, which is a standard light source, and indicates the average daylight color. The spectral reflectance of the phosphor element group 2 on the fluorescent surface is almost flat in the visible light region, and the spectral transmittance of the face plate glass 1 has a nearly flat distribution in the visible light region, like conventional clear glass. In this case, the chromaticity point of the reflected external light reflected by the fluorescent surface, that is, the body color of the fluorescent surface, exhibits a value almost close to the chromaticity point of the external light. On the other hand, when neodymium-containing glass is used as a face plate glass for a fluorescent surface, the spectral transmittance of the face plate glass is not flat in the visible light range but has complex undulations as described above, so the light is reflected from the fluorescent surface and the light is emitted. The chromaticity point of the reflected external light, that is, the body color of the fluorescent surface, is different from the chromaticity point of the white external light. That is, to explain the case of light source A (point A) in FIG. 5, when the external light is from light source A, the external light incident on the phosphor surface is almost flat in the visible light region in phosphor element group 2. Although some reflection occurs, the steep absorption in the 580 nm main absorption band of neodymium-containing glass
Due to the absorption in the sub-absorption band of 530 nm, the wavelength component of the reflected external light becomes different from that of the originally incident external light. Looking at these effects on a chromaticity diagram
Due to the main absorption band of 580nm, the light of this wavelength component in the external light is reduced, and the chromaticity point is the line segment β connecting the 580nm monochromatic chromaticity point (point Q on the horseshoe shape) and the chromaticity point A of the A light source.
The upper surface is influenced to move away from the monochromatic point Q at 580 nm (this is shown by vector _a2 ). similarly
The 530nm sub-absorption band reduces the wavelength component of the external light, and the chromaticity point of the reflected external light connects the monochromaticity point of 530nm (point R on the horseshoe shape) and the chromaticity point A of the A light source. It is affected in such a way that it moves away from the monochromatic point R of 530 nm on the line segment α. (This is shown by vector a _1. )
Therefore, the chromaticity point of the reflected extraneous light, that is, the body color of the fluorescent surface moves in the direction of vector _a3 , which is the combination of these two vectors _a1 and _a2 . Also, since the absorption in the main absorption band is much larger than that in the sub-absorption band, the absolute value of vector a ₂ is sufficiently larger than the absolute value of vector a ₁ . Similarly, in the case of a white fluorescent lamp (point B) and a light source C (point C), the chromaticity point of the reflected extraneous light, that is, the body color of the fluorescent surface, moves in the directions of vectors _b3 and _c3 , respectively. In this case as well, the absolute values of vectors b ₂ and c ₂ are sufficiently larger than the absolute values of vectors b ₁ and c ₁ due to the difference in the magnitude of absorption between the main absorption band and the sub absorption band. As mentioned above, when neodymium-containing glass is used as the face plate glass of the fluorescent surface, the body color of the fluorescent surface deviates from the color tone of the white external light, which is a source of concern and is not desirable in terms of the appearance of the fluorescent surface.

This invention was made in view of the problem that the color of the fluorescent surface becomes unstable when such neodymium-containing glass is used as the face plate glass of a color cathode ray tube. To provide a color cathode ray tube in which the body color of a fluorescent surface is stable even when glass is used as a face plate glass.

Embodiments of the present invention will be described below with reference to FIGS. 5 to 13. First, the principle of this invention will be explained with reference to FIG. 5 mentioned above. As mentioned above, when neodymium-containing glass is used as the face plate glass of the fluorescent surface, the vector (a ₂ , b ₂ , c ₂ ) on the chromaticity diagram caused by the main absorption band at 580 nm and the sub absorption band at 530 nm are vector (a ₁ , b ₁ , c ₁ )
However, the size of the vector (a ₁ , b ₁ , c ₁ ) is sufficiently small compared to the size of (a ₂ , b ₂ , c ₂ ). Therefore, the present invention attempts to stabilize the body color of the fluorescent surface by focusing on these vectors (a ₂ , b ₂ , c ₂ ). To eliminate the influence of such vectors (a ₂ , b ₂ , c ₂ ), the inverse vectors of these vectors, ie (-a ₂ , -b ₂ , -
It is clear that it is better to generate c ₂ ). The method for generating this inverse vector will be explained in detail for the case of chromaticity point A of light source A. Line segment β connecting the monochromatic chromaticity point Q of the main absorption band of 580 nm and the chromaticity point A of the A light source
The point where Qa intersects with the horseshoe curve again (point Qa) is approximately
The monochromatic chromaticity point is 470nm, but if we somehow reduce the amount of light with a wavelength component of about 470nm among the wavelength components of reflected external light, the chromaticity point will be about 470nm.
Under the influence of moving away from the monochromatic chromaticity point Qa on the line segment β connecting the monochromatic chromaticity point Qa of and the chromaticity point (A) of the A light source,
It is clear that a vector of -a ₂ is generated. In the case of other types of white external light, the intersection points Qb and Qc of this line segment εδ with the horseshoe curve are located around 480 nm, and if the light of these wavelength components in the reflected external light is reduced by an appropriate amount, -b ₂ and −c ₂ vectors can be generated. In other words, when neodymium-containing glass is used as a face plate glass for a fluorescent surface, if the light with a wavelength component of 470 to 480 nm in the reflected external light is reduced by an appropriate amount, changes in the body color of the fluorescent surface can be almost eliminated. is possible.

It is clear that the way to reduce the light in the wavelength range of 470 to 480 nm in the reflected external light is to attenuate the spectral reflectance of the three-color phosphor element group 2 in the wavelength range of 470 to 480 nm. . The present inventors have proposed various phosphors that can be used as three-color phosphor elements in the fluorescent surface of color cathode ray tubes based on their emission spectra, and have investigated the structure of the fluorescent surface when combined with a neodymium-containing face plate glass. As a result of examining color stability, a copper-activated, aluminum-coactivated zinc sulfide (ZnS:Cu,Al) phosphor was selected as the green (G) color-emitting phosphor element of the three-color phosphor element group 2. It was discovered that by using this method, a fluorescent surface with more stable body color could be obtained. The present invention will be explained in more detail with reference to FIGS. 6 to 13 below.

FIG. 6 shows the spectral reflection characteristics of an unfavorable combination of the three-color phosphor element group 2. That is, a terbium-activated gadolinium oxysulfide (Gd ₂ O ₂ S:Tb) phosphor is used as a green (G) color emitting phosphor element of the three-color phosphor element group 2 to produce a blue (B) color emitting fluorescent light. Silver-activated zinc sulfide (ZnS:Ag) as a body element
The phosphor is also made of europium-activated yttrium oxysulfide (Y ₂ O ₂ S:
Spectral reflection characteristics of each phosphor when Eu) phosphors are used and spectral reflection of three-color phosphor element group 2 when these phosphors form three-color phosphor element group 2 This shows the characteristics of Gd ₂ O ₂ S in the figure.
Tb phosphor, B is ZnS: Ag phosphor, C is Y ₂ O ₂ S:
2 is a spectral reflectance curve for each of the three-color phosphor element group 2, which is a combination of these three-color phosphors. In the case of a combination of these phosphors, the spectral reflection curve 2 of the three-color phosphor element group 2 shows almost no attenuation in the wavelength range of 470 to 480 nm, which is unfavorable due to the color of the phosphor surface for the reasons mentioned above. It is. FIG. 7 shows the spectral reflection characteristics of a preferred combination of three-color phosphor element group 2. In this case, the blue (B) and red (R) color emitting phosphors are the phosphors shown in FIG.
Fluorophor and _Y2O2S : Same as Eu fluorophore _but green
(G) A ZnS:Cu,Al phosphor is used as the color-emitting phosphor, and E in the figure shows the spectral reflectance curve of this phosphor. In this case, the spectral reflectance curve of the integrated three-color phosphor element group 2 is as shown in the figure below, and it shows attenuation in the wavelength band of 470 to 480 nm, so when combined with a neodymium-containing face plate glass, This is preferable in terms of the body color of the fluorescent surface. This is because the spectral reflectance curve H of the ZnS:Cu,Al phosphor used as the green (G) color emitting phosphor in the three-color phosphor element group 2 is on the short wavelength side of the visible light region as shown in the figure. This is because it is greatly attenuated. Also this ZnS:
The attenuation of the spectral reflectance of Cu and Al phosphors on the short wavelength side of the visible light region is due to copper (Cu, the activator of this phosphor).
Much depends on the amount of In the case of the ZnS:Cu,Al phosphor shown in the spectral reflectance curve E, approximately 1×10 ^-4 g of copper (Cu) activator was activated for 1 g of zinc sulfide (ZnS) as the base material. As the activator concentration of copper (Cu) increases, the attenuation of the spectral reflectance of the phosphor on the short wavelength side of the visible light region increases. Figure 8 shows ZnS:Cu,Al used as a green (G) color emitting phosphor.
This is an example in which the copper (Cu) activator concentration is further increased, and the blue (B) and red (R) color emitting phosphors are the same as in Figures 6 and 7, respectively. Fluorescent material _{and Y2O2S} :Eu fluorescent material. In this case, the copper (Cu) activator was activated in an amount of approximately 5×10 ⁻⁴ g per gram of zinc sulfide, which was the base material. The spectral reflectance curve of the ZnS:Cu,Al phosphor in this case is as shown in (G) in the figure, and the attenuation on the short wavelength side of the visible light region is even greater than in the case (E) of FIG. As a result, the spectral reflectance curve of the three-color phosphor element group 2 is as shown in FIG.

When the combination of the three-color phosphor element group 2 as described above is formed on the inner surface of a face plate glass of conventional clear glass and neodymium-containing glass, the body color of the phosphor surface is determined by the white external light from the light source A. Figure 9 shows the case plotted on the CIE chromaticity diagram. In the figure, A is the chromaticity point of light from the A light source. P is a conventional clear glass face plate glass 1 with Gd ₂ O ₂ S: Tb green (G) color emitting phosphor, ZnS: Ag blue (B) color phosphor, and Y ₂ O ₂ S: Eu Fluorescent surface when a three-color phosphor element group 2 is formed, which is composed of a combination of red (R) color-emitting phosphors and has an almost flat spectral reflectance in the visible light region, as shown in FIG. 6D. This shows the chromaticity point of the external light reflected from the surface, that is, the body color of the fluorescent surface. The reason why there is a slight difference between A and P is that the spectral transmittance of clear glass is actually not completely flat in the visible light range, but has slight irregularities, as shown in Figure 2a, and the fact that the three-color phosphor element This is because the spectral reflectance of group 2 is slightly uneven. On the other hand, on the inner surface of the face plate glass 1 made of neodymium-containing glass, the Gd ₂ O ₂ S:Tb green (G) color emitting phosphor described in the example of the combination of the undesirable three-color phosphor element group 2 shown in FIG. ZnS: Ag blue (B) color emitting phosphor and
Y ₂ O ₂ S: The chromaticity point of the external light reflected from the fluorescent surface when forming the three-color phosphor element group 2 consisting of a combination of Eu red (R) color emitting phosphors, that is, the chromaticity point of the fluorescent surface. Point E indicates the chromaticity point of the body color. In this case, the body color of the fluorescent surface deviates greatly from the chromaticity point A of the white extraneous light, that is, the light source A, resulting in an unstable color tone, which is unfavorable in terms of the appearance of the fluorescent surface. Point F is described in the preferred combination example of three-color phosphor element group 2 in FIG. 7 above.
ZnS: Cu, Al green (G) color emitting phosphor, ZnS: Ag blue (B)
A case where a three-color phosphor element group 2 consisting of a combination of a color-emitting phosphor and a Y ₂ O ₂ S:Eu red (R) color-emitting phosphor is formed on the inner surface of a face plate glass 1 made of neodymium-containing glass. This shows the body color of the fluorescent surface, and as mentioned above, the light component in the wavelength band of 470 to 480 nm in the reflected external light is reduced, and the deviation from the chromaticity point A of the A light source is much smaller than that at the E point. It's summery.
As explained in Figure 8, the G point is a green (G) fluorescent phosphor with an increased concentration of copper (Cu) activator.
This shows the light color of the phosphor surface when ZnS:Cu,Al phosphor is applied to the three-color phosphor element group 2, and the deviation from the chromaticity point A of the A light source is even smaller than the above-mentioned point F.

ZnS: Cu, Al In terms of the amount of copper (Cu) activator in the phosphor contributing to the stability of the body color of the phosphor surface using neodymium-containing glass face plate glass, zinc sulfide as the matrix It is desirable that the additive amount of copper (Cu) be 5×10 ^-5 g or more per 1 g. More preferably, if the amount of copper (Cu) used as an additive is 3×10 ^-4 g or more, the stability of the body color of the fluorescent surface can be greatly increased.

Figures 10 to 13 show blue-pigmented silver-activated zinc sulfide (blue-pigmented silver-activated zinc sulfide), which has recently become widely used for the purpose of improving the contrast of the fluorescent surface.
A ZnS:Ag) phosphor was used as a blue-emitting phosphor, and a europium-activated yttrium oxysulfide ( _Y2O2S :Eu) phosphor with a red pigment was used as a red-emitting phosphor _. The spectral reflectance of the three-color phosphor element group 2 when the various green (G) color-emitting phosphors described above are combined (Figures 10 to 12) and the spectral reflectance of the three-color phosphor element group 2 The body color of the fluorescent surface formed on the inner surface of the face plate glass 1 of conventional clear glass and neodymium-containing glass is plotted on the ClE chromaticity diagram when the white external light is from light source A (No. 13). ) to the above-mentioned figure 6~
This is shown similarly to FIG. 9. In the figure, R is the spectral reflectance curve of the blue pigmented ZnS:Ag phosphor, and N is the spectral reflectance curve of the red pigmented Y ₂ O ₂ S:Eu _phosphor . The spectral reflectance curve of the three-color phosphor element group 2 in combination with the O ₂ S:Tb phosphor shows almost no attenuation in the wavelength band of 470 to 480 nm, as shown in Figure 10. When combined with Al phosphor, 470 ~ as shown in Figure 11
Attenuation occurs in the 480nm wavelength band. Similarly to the above, when these phosphors are combined with a ZnS:Cu,Al phosphor with an increased concentration of copper (Cu) activator, the 470 of three-color phosphor element group 2 as shown in FIG. The spectral reflectance in the ~480 nm wavelength band is further attenuated. When the three-color phosphor element group 2 of these combinations is formed on the inner surface of the conventional face plate glass 1 made of clear glass and neodymium-containing glass, the body color of the phosphor surface is the same as that of the light from the light source A. Figure 13 shows the case on the CIE chromaticity diagram, where A is the chromaticity point of the A light source, H is the Gd ₂ O ₂ S:Tb phosphor, the ZnS:Ag phosphor with blue pigment, and the red color. With pigment
Y ₂ O ₂ S: Chromaticity of external light reflected from the phosphor surface when the three-color phosphor element group 2 consisting of a combination of Eu phosphors is formed on the inner surface of the conventional clear glass face plate glass 1 point, that is, the chromaticity point of the body color of the fluorescent surface, I is Gd ₂ O ₂ S:Tb phosphor, with blue pigment
A three-color phosphor element group 2 consisting of a combination of a ZnS:Ag phosphor and a red pigmented Y ₂ O ₂ S:Eu phosphor is attached to a face plate glass 1 made of neodymium-containing glass.
The chromaticity point of reflected external light from the fluorescent surface when formed on the inner surface, that is, the chromaticity point of the body color of the fluorescent surface, J is ZnS:
A three-color phosphor element group 2 consisting of a combination of Cu, Al phosphor, blue pigmented ZnS:Ag phosphor, and red pigmented Y ₂ O ₂ S:Eu phosphor is attached to a neodymium-containing face plate glass. 1. When formed on the inner surface, the chromaticity point of reflected external light from the fluorescent surface, that is, the chromaticity point of the body color of the fluorescent surface, K is ZnS with increased concentration of copper (Cu) activator: Cu, Al Phosphor, blue pigmented ZnS:
When a three-color phosphor element group 2 consisting of a combination of an Ag phosphor and a red pigmented Y ₂ O ₂ S:Eu phosphor is formed on the inner surface of the neodymium-containing face plate glass 1, This is the chromaticity point of reflected external light, that is, the chromaticity point of the body color of the fluorescent surface. As is clear from these chromaticity points, even when using a pigmented blue (B) color emitting phosphor and a red (R) color emitting phosphor, the color is green.
(G) If ZnS:Cu, Al phosphors are combined as color-emitting phosphors, 470~
The light component in the 480 nm wavelength band is reduced, and the instability of body color that occurs when combined with the face plate glass 1 made of neodymium-containing glass is greatly improved. That is, the chromaticity point of the body color returns from I to J.
In addition, by increasing the copper (Cu) activator concentration in the ZnS:Cu,Al phosphor, the light component in the wavelength band of 470 to 480 nm in the reflected external light is further reduced, and the body color of the phosphor surface is stabilized. The sex will further increase. That is, the chromaticity point of the body color returns to K.

The above description is based on the case where the light source of white external light is A light source, but in the case of white external light from a white fluorescent lamp or C light source, ZnS is used as a green (G) color emitting phosphor.
By using Cu and Al phosphors, the light component in the wavelength band of 470 to 480 nm in the reflected external light is reduced, making it possible to obtain similar efficiency.

In addition, recently, a Brarritz matrix type fluorescent surface, in which a light absorption layer is provided between the three-color phosphor elements of the fluorescent surface, has come into general use for the purpose of increasing the contrast of the fluorescent surface. However, the present invention can be similarly applied to such fluorescent surfaces.

As described above, according to the present invention, the problem of instability of the body color of the fluorescent surface when neodymium-containing glass is used as a face plate glass can be solved by using ZnS:Cu as a green (G) color emitting phosphor. A cathode ray tube of very high quality, with improved contrast and brightness characteristics that have been improved by combining a group of three-color phosphor elements using Al phosphors to obtain a phosphor surface with a sufficiently stable and calm body color. It becomes possible to provide

[Brief explanation of the drawing]

Figure 1 is a diagram showing a cross-sectional model of the fluorescent surface of a cathode ray tube, Figure 2 is a diagram showing typical spectral transmittance curves of various glasses, and Figure 3 is a diagram showing a spectral transmittance curve of neodymium-containing glass. , Figure 4 is a diagram showing the spectral transmittance curves of neodymium-containing glass and clear glass, Figure 5 is a diagram showing the chromaticity point of white external light on the white diagram on the CIE chromaticity diagram, and Figures 6~ Figure 8 is a diagram showing the spectral reflection characteristics of a group of three-color phosphor elements based on combinations of various phosphors, and Figure 9 plots the chromaticity points of the body colors of various phosphor surfaces on the CIE chromaticity diagram. Figure 10
Figures 1 to 12 show 3 combinations of various phosphors.
Diagram showing the spectral reflection characteristics of color phosphor element groups, No. 13
The figure shows the chromaticity points of the body colors of various fluorescent surfaces plotted on the CIE chromaticity diagram. In the figure, 1 is a face plate glass, and 2 is a group of three-color phosphor elements of red (R), green (G), and blue (B).

Claims (1)

[Claims] 1. A fluorescent surface is constituted by a face plate glass containing neodymium oxide (Nd ₂ O ₃ ) and a group of phosphor elements of multiple colors provided on the inner surface of the face plate glass. 1. A cathode ray tube characterized in that a copper-activated aluminum co-activated zinc sulfide (ZnS:Cu,Al) phosphor is used as a green-emitting phosphor element of the phosphor surface. 2. The cathode ray according to claim 1, characterized in that the amount of copper (Cu) as an activator is 3×10 ^-4 g or more per 1 g of zinc sulfide (ZnS) as a base material. tube.