JPS633419B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a picture tube, and particularly to a picture tube having high contrast and high brightness characteristics.

Various methods have been proposed and put into practical use in order to improve the contrast of images against brighter external light than ever before. For example, one of these methods is
There are face plates with a fluorescent film coated on the inner wall that lowers the transmittance and improves contrast, and the light transmittance is about 65% and 65%, respectively, compared to the so-called clear panel, which has a light transmittance of about 85%. 55% gray panels and tainted panels have been put into practical use.
In this case, one way to reduce the light transmittance of these face plates is to add a very small amount of a coloring agent such as Co or Ni as an oxidizing agent during the production of panel glass. can.

With a face plate configured in this way, images with higher contrast can be obtained by lowering the light transmittance, and the manufacturing process for picture tubes is exactly the same, without complicating the process or increasing costs. , is a very good method. However, it has the disadvantage that the brightness (luminance) of the fluorescent film is impaired by the amount of light transmittance of the face plate reduced.

Another method for improving the contrast of an image is to provide a black light absorbing layer between the face plate and the phosphor layer, which partially covers the face plate. i.e. blue, red,
A black light absorbing layer is provided around each picture element of the green light emitting phosphor, and the black light absorbing layer absorbs external light transmitted through the face plate.

According to such a configuration, the light-emitting part on the phosphor screen usually occupies 60-70% of the screen, and about 30-40% of the screen becomes the non-light-emitting part, and this non-light-emitting part is covered with a black light absorption layer. By providing this, contrast can be increased without impairing brightness. In order to further increase the contrast using this method, there is a method of widening the black light absorbing layer by 50 to 60% of the luminescent screen, but in this case, only widening the non-luminous layer is necessary. The light emitting area becomes narrower and the brightness of the image is sacrificed.

Furthermore, another method for improving the contrast of images is to selectively transmit (or reflect) only the light corresponding to the light emitted by the phosphors of two or three colors to the phosphors of two or three colors. A filter material that selectively absorbs light other than that corresponding to the phosphor layer is provided in a layer between the phosphor layer and the inner surface of the face plate, or is mixed into the phosphor layer, or is attached to the phosphor surface. There is a way.

However, in such a method, currently applicable filter materials have a light transmittance (or reflectance) of 50 to 90%, which corresponds to the light emitted by the phosphor.
The absorption rate of light other than the light emitted by the phosphor is 50-100%, so even if a filter material is applied, the brightness will decrease, and even if it is possible to slightly suppress the reflection of external light on the screen. The disadvantage in terms of integrated characteristics was greater.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the picture tube, and to provide a picture tube that can provide high-contrast, high-brightness images in a simple manner. be.

In order to achieve such an object, the picture tube according to the present invention calculates the spectral transmittance of the face plate at the peak wavelength of each emission color of the phosphor, that is, the wavelength at which the emission intensity shows a peak value. This is 5% or more higher than the minimum spectral transmittance of the face plate between the peak wavelengths. The picture tube according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of a main part of a color picture tube fluorescent surface for explaining an example of a picture tube according to the present invention.
In the figure, in order to obtain a color image, the phosphor surface of a color picture tube is coated with phosphor layers 2, 3, and 4 that emit red, green, and blue light at predetermined positions on the inner wall surface of a face plate 1. ing. Then, from the back side, three electron beams 5, 6, corresponding to the three colors,
7 stimulates the phosphor layers 2, 3, and 4 of three colors to emit light, and the three emitted light colors 8, 9, and 10 are transmitted through the face plate 1 and an image is projected. When bright external light 11 hits the front side of the face plate 1, that is, the observer side, this external light 1
1 passes through the face plate 1 and reaches the red, green, and blue phosphor layers 2, 3, and 4, the phosphor layers 2,
The light is reflected by surfaces 3 and 4, passes through the face plate 1 again, and is reflected back to the viewer as reflected light 12. As a result, the three emission colors 8, 9, and 10 are as follows.
When the external light 11 becomes stronger, the reflected light 12 becomes even stronger with respect to the signal component that transmits image information emitted by the electron beams 5, 6, and 7, and the contrast is significantly reduced. Therefore, in order to improve the contrast, the light transmittance of the face plate 1 is lowered and the reflected light 1 from the external light 11 is reduced.
Efforts have been made to reduce the number of 2. In other words, when manufacturing face plates, trace amounts of NiO and CoO are added to the main components such as SiO ₂ and Na ₂ O.
The spectral transmittance in the visible range can be arbitrarily changed by adding such materials as clear panels, gray panels, and taint panels having the spectral transmittances shown at 13, 14, and 15 in FIG. 2. On the other hand, 3
The phosphor layers 2, 3, and 4 that emit light in different colors include Y ₂ O ₂ S:Eu for the red phosphor layer 2 and ZnS: for the green phosphor layer 3.
CuAl, blue phosphor layer 4 contains ZnS:Ag,
It has red, green, and blue phosphor emission spectra shown at 16, 17, and 18 in FIG. And the third
When the phosphor layers 2, 3, and 4 having the red, green, and blue phosphor emission spectra shown in the figure are transmitted through the face plate having the respective transmittances shown in FIG. The light of the emitted color is reduced by the amount of light absorbed by the face plate. Therefore, a face plate with low transmittance can prevent a decrease in contrast due to external light, but the brightness will decrease.

Therefore, the picture tube according to the invention, in particular its face plate, is characterized in that 0.01 to 5% by weight of rare earth element oxides such as Er ₂ O ₃ , Nd ₂ O ₃ are added when manufacturing the face plate panel, and a second A face plate having the spectral transmittance curve 19 shown in FIG. 4 is constructed with the spectral transmittance characteristics of a clear panel as shown by 13 in the figure.

In the face plate constructed in this way, by adding Er ₂ O ₃ , the emission wavelengths correspond to those between the blue phosphor spectrum 18 and the green phosphor spectrum 17 shown in FIG. The spectral transmittance between wavelengths in the range shown by the trough 19a of the spectral transmittance curve 19 in FIG. 4 decreases, and light absorption occurs between these wavelengths. In this example, the thickness of the face plate was 10 mm, and 0.3% by weight of Er ₂ O ₃ was added. Furthermore, by adding Nd ₂ O ₂ , the spectral transmittance curve 19 in FIG. 4 corresponding to the emission wavelength between the green phosphor spectrum 17 and the red phosphor spectrum 16 shown in FIG. The spectral transmittance between wavelengths in the range shown by the trough 19b decreases, and light absorption occurs between these wavelengths. Note that in this example, Nd ₂ O ₃ is
In order to reduce the transmittance of the face plate, that is, the spectral transmittance by 5% or more by adding rare earth element compounds such as Nd ₂ O ₃ and Er ₂ O ₃ , It is necessary to add 0.01% by weight or more. Furthermore, as the amount of these rare earth element compounds added increases, the spectral transmittance decreases as described above, but when the amount added exceeds 5% by weight, the properties of the glass, such as the dielectric constant, change. , will have undesirable properties. Therefore, rare earth element oxides
It is desirable to add it in a range of 0.01 to 5% by weight.

In addition, within this addition amount range, the three-color phosphor layer 2,
The brightness due to the light emission of 3 and 4 hardly decreases compared to a clear panel. Further, in this case, the transmittance (luminous transmittance) T related to contrast is expressed as T=∫P(λ)·f(a)·dλ/∫P(λ)·ydλ. Here, P(λ): Spectral composition of radiation from the light source: Stimulus value in the CIE display system (standard luminous efficiency curve) f(a): Spectral transmittance of the face plate. If Er ₂ O ₃ and Nd ₂ O ₃ are added to give a sensitive transmittance, the same contrast as a gray panel can be obtained. In this case, the brightness of the image was approximately 23% brighter compared to the gray panel, and the contrast was equivalent to that of the gray panel. Furthermore, the 3
The spectral spectrum of the emitted color was sharp, and an image with good saturation, that is, good color purity, was obtained. Here, if the difference between the peak wavelength of light emission of the phosphor and the spectral transmittance between them is 5% or less,
There is no effect of improving contrast, and 5% or more is required. Further, when the amount is less than 5%, not only is the effect of improving the contrast small, but also no effect was observed in the evaluation of the image quality of the fluorescent screen. Furthermore, even if Co and Ni are added to make the contrast the same as described above, the brightness is only improved by about 3%, and the effect of the present application cannot be obtained. When the difference exceeds 5%, the visual difference becomes obvious.

In addition, it was added to the face plate glass.
Rare earth oxides of Er ₂ O ₃ and Nd ₂ O ₃ are 0.01 to 5% by weight
By changing the amount added within the range, the spectral transmittance of the face plate at the peak wavelength of each emission color can be made 5% or more higher than the spectral transmittance of the face plate between each peak wavelength of each emission color, Extremely good high contrast and high brightness characteristics were obtained. Furthermore, in general, the 4f electrons in the electron shell of rare earth element ions do not exhibit strong crystal field dependence like the 3d electrons of transition elements due to the shielding effect of outer shell electrons.
Glasses exhibit narrow absorption bands similar to crystals and liquids. Therefore, the lanthanide series Ce, Pr,
Glasses (face plates) containing elements such as Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, and Tm have similar effects. The above element has absorption in the face plate at a short wavelength between 450 and 540 nm between the peak wavelengths of the phosphor and/or at a long wavelength between 550 and 600 nm. Therefore, desired contrast can be obtained by using these elements alone or in combination. For example, Nd, Er, Pr, Dy,
Sm, Gd, and Ho have absorption on the short wavelength side, and Nd, Pr, and Ho have absorption on the long wavelength side, although the absorption intensities differ. Moreover, there are some elements in which one element has absorption over a plurality of different wavelengths.

In the production of face plates, these elements or compounds, such as oxides, nitrates, and chlorides, are used as raw materials, and generally exist in the form of oxides in face plates. Therefore, even when they are used as elements or compounds as raw materials, they are treated as oxides alone or in combination. This is shown in FIGS. 5 to 9.

Figure 5 shows Er ₂ O ₃ : 0.6% by weight, Gd ₂ O ₃ : 0.7% by weight.
In Figure 6, a is Er ₂ O ₃ : 0.1% by weight;
Nd ₂ O ₃ : 0.3% by weight, b is Er ₂ O ₃ : 0.4% by weight,
Nd ₂ O ₃ : 1.2% by weight, Figure 7 shows Nd ₂ O ₃ : 1.8% by weight
Fig. 8 is Pr ₂ O ₃ :2.6% by weight, Fig. 9
The figure shows Dy ₂ O ₃ : 1.2 weight %, Sm ₂ O ₃ : 1.2 weight %
Ho ₂ O ₃ : 0.6% by weight is shown. Note that in these cases, the face plate thickness was 10 mm.

Furthermore, what is required of the face plate is the body color of the face plate. In order to make the color reproduction formed by the light emission of the three colors of phosphors according to the signal faithful to the signal, it is necessary to make the body color of the face plate achromatic. However, the body color of the face plates currently in practical use tends to be slightly blue. Therefore, the color of the face plate is also considered to be an extremely important factor in order to maintain image quality.

Furthermore, by adding commonly used coloring agents such as CoO and Fe ₂ O ₃ , it was possible to match any body color of face plates currently in practical use. In this case as well, the brightness of the image is the same as that of a clear panel, and the contrast is gray.
I was able to make it similar to a taint panel.

Furthermore, the present invention can also be applied to the color picture tube having the black light absorbing layer and the method of adding a filter material to the phosphor layer to improve the contrast, and it is possible to further improve the contrast. Become.

As explained above, according to the picture tube according to the present invention, the brightness of the image is equivalent to that of a clear panel, and the contrast is equivalent to that of a gray panel or a tainted panel. Effects can be obtained.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of essential parts showing an example of the phosphor surface of a color picture tube, Figure 2 is the spectral transmittance curve of the color picture tube face plate panel, Figure 3 is the emission spectrum of the phosphor, and Figures 4 to 4. FIG. 9 is a spectral transmittance curve of a color picture tube face plate according to the present invention. 1...Face plate, 2...Red phosphor layer,
3... Green phosphor layer, 4... Blue phosphor layer, 5, 6,
7... Red, green, blue electron beam, 8, 9, 10...
Red, green, blue light, 11...External light, 12...Reflected light, 13...Clear panel spectral transmittance curve, 14
... Gray panel spectral transmittance curve, 15 ... Tainted panel spectral transmittance curve, 16 ... Red phosphor emission spectrum, 17 ... Green phosphor emission spectrum, 18 ... Blue phosphor emission spectrum, 19 ……
Face plate spectral transmittance curve, 19a, 19
b...Tanibe.

Claims (1)

[Claims] 1. In a picture tube in which three color phosphors are coated on the inner surface of a face plate, the face plate has a material composition that emits higher light at wavelengths between the peak wavelengths of the emission colors of the phosphors than at the peak wavelengths. Rare earth element oxides with absorption rate
A picture tube characterized in that the content is in the range of 0.01 to 5% by weight, and the minimum spectral transmittance between the peak wavelengths is lowered by 5% or more with respect to the spectral transmittance at the peak wavelength.