JPH03159034A - Cathode-ray tube faceplate - Google Patents

Abstract

PURPOSE:To prevent coloring of a filter resulting from continuous radiation of electron beams by adding and soaking the oxide of a specified element to at least one of every two different layers of a laminate prepared through the process of making alternate lamination of the low refractive index layer and the high refractive index layer in order of the one layer in contact with a phosphor layer and then specifying the refractive index ratio of the low refractive index layer to the high refractive index layer. CONSTITUTION:An optical interference filter 4 formed of a laminate prepared through the process of making alternate lamination of a low refractive index layer 2 and a high refractive index layer 3 is provided between a phosphor layer 5 provided on the inner face of display window of a cathode-ray tube faceplate 1 and the display window. At least one oxide selected from the oxides of lanthanoid system elements formed respectively of La2O3, CeO2 and the like is then added to and soaked in at least one of every two different layers, alternately laminated, in order of the one layer 2a in contact with the phosphor layer 5. Furthermore, the ratio of the refractive index of the low refractive index layer 2 to that of the high refractive index layer 3 is specified to have not more that 0.80. This can prevent coloring of the filter 4 resulting from the entry of electron beams or X-rays radiated onto the surface of the faceplate, into the filter.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a cathode ray tube face plate of a television, and a phosphor layer provided between an inner surface of a cathode ray tube face plate and a phosphor layer coated on the inner surface of the cathode ray tube face plate. The cathode ray tube face plate has an optical interference filter consisting of multiple layers of alternating high-refractive index materials and low-refractive index materials, and in particular, images in front are projected onto the screen via a projection lens placed opposite to the phosphor surface. The present invention relates to a face plate of a projection type cathode ray tube.

[Prior Art] Display by a projection type television that displays a large image by projecting an image onto a screen emits a single blue, green, and red light, respectively, as shown in FIG. 3(a). Each of the blue, green, and red cathode ray tubes has an optical system that condenses the light from the three projection cathode ray tubes 31 using a lens 32, and this is done by projecting each image onto a screen 33. . In the projection type cathode ray tube 31 used here, a phosphor layer 5 is coated on the inner surface of the cathode ray tube face plate 1, as shown in FIG. 3(b), and this phosphor layer 5 and the cathode ray tube face plate 1 In some cases, an optical interference filter 4 made of alternating layers, such as a short-pass edge filter, is provided between the inner surface of the filter and the inner surface of the filter.

As such an optical interference filter, for example, as shown in FIG. 4, an optical interference filter whose cutoff wavelength is a wavelength λ0 slightly longer than the center wavelength λ of the emission spectrum of the phosphor is used. is disclosed in Japanese Patent Application Laid-Open No. 61-273837.

[Problems to be Solved by the Invention] The performance required of the optical interference filter provided on the cathode ray tube face plate described above is that it has good wavelength selectivity of light, and also has a phosphor that emits light when irradiated with an electron beam. It is necessary to efficiently extract this light to the outside of the display window of the cathode ray tube face plate. Therefore, it is important that the so-called browning phenomenon, in which the optical interference filter is colored and blackened by irradiated electron beams or X-rays, does not occur.

However, a cathode ray tube face plate provided with a conventional optical interference filter has a problem in that coloration occurs due to continuous irradiation with electron beams, making it impossible to efficiently extract light emitted from the phosphor to the outside.

The present invention provides a cathode ray tube face plate that is equipped with an optical interference filter that does not cause the Browning phenomenon even when irradiated with electron beams or X-rays for a long period of time, and that can efficiently extract the luminescence of the phosphor to the outside of the display window. It is something to do.

[Means for Solving the Problems] The present invention provides a structure in which a low refractive index layer and a high refractive index layer are provided between a phosphor layer provided on the inner surface of a display window of a cathode ray tube face plate and the display window. A cathode ray tube face plate provided with an optical interference filter consisting of alternately laminated layers, wherein at least one of the alternately laminated layers has L.
a 203゜CeO2, P "At least one selected from oxides of lanthanide elements consisting of 203.Nd2O3
A cathode ray tube face plate, in which the ratio of the refractive index of the low refractive index layer to the refractive index of the high refractive index layer is 0.80 or less. be.

The main component of the low refractive index layer is A11203SIOMgF.
2 are preferred and these 2.

The materials each have a refractive index of approximately 1.6 by a known vapor deposition method.
3. Approximately 1.45. There may be approximately 1.38 layers.

Furthermore, the above-mentioned materials La OCeO2゜2 3' Pr2O3 and Nd2O3 have refractive indexes of approximately 1.9. Approximately 2.0. approx. 2.0° approx. 2,
1 transparent layer. It is generally recognized that the refractive index of a deposited layer consisting of two or more components has a linear additivity relationship with the refractive index of a layer consisting of each component alone, depending on the self-existence rate of the components. Also in the optical interference filter according to the present invention, as the amount of the oxide of the lanthanoid element having a relatively high refractive index added to the low refractive index layer increases, the refractive index of the low refractive index layer linearly increases. Become. In the optical interference filter according to the present invention, the ratio of the refractive index of the low refractive index layer to the refractive index of the high refractive index layer is selected to be 0.80 or less. When the ratio exceeds 0.80, the optical characteristics deteriorate. For example, the cutoff characteristic of light at wavelength λ0 in FIG. 4 becomes less steep, and the color characteristics of the projected image deteriorate.

The main component of the high refractive index layer is TiO2゜ZrOTa
One selected from the group consisting of OHfO2 is preferably used. These oxides are
By a known vapor deposition method, the refractive index is approximately 2J5. Abbreviation 2
．． 1. Abbreviation 2.1. The refractive index of the high refractive index layer does not change significantly even when the oxide of the lanthanoid element described above is added to the high refractive index layer.

The upper limit of the oxide of the lanthanoid element that can be added to the low refractive index layer in order to make the ratio of the refractive index of the low refractive index layer to the refractive index of the high refractive index layer 0.8 or less is: It is related to the main component of the low refractive index layer and the main component of the high refractive index layer, and cannot be uniquely determined. For example, if the high refractive index layer is 1
When the low refractive index layer is composed of 99 wt.% TiO2 and the main component of the low refractive index layer is SiO2, Ce O2 in the low refractive index layer can be added up to 56 wt.%.

In addition, the high refractive index layer is 0.5%CeO99,5%Tt
The main component of the low refractive index layer is A I 20 a
, CeO2 is 35% by weight in the low refractive index layer.
Can be added up to.

In order to prevent coloring from occurring due to irradiation with electron beams or X-rays, the amount of the oxide of the lanthanide element described above may be small, and is usually added in an amount of 0.3% by weight or more. On the other hand, since the layer of the above-mentioned lanthanide-based element oxide tends to become a layer that absorbs light when coated, it is preferable that the layer be small in order to obtain a transparent optical interference filter. Therefore, it is usually preferable to add it in a range of 0.3 to 10% by weight.

Further, the number of layers of the optical interference filter according to the present invention is determined depending on the required optical properties, such as the steepness of the cutoff characteristic, the tolerance of light leakage in the reflection band, and the like. Usually, the number of layers used is preferably 5 to 30 layers, preferably 10 to 25 layers. Further, the optical interference filter according to the present invention can be manufactured by using a known electron beam evaporation method or ion blating method.

The center wavelength λ of the emission spectrum of the phosphor layer emitted by electron beam irradiation and the cutoff wavelength λ serving as the design standard for the optical interference filter. The relationship with is λ.

is set to be larger than 1.05λ and smaller than 50λ. When λ0 is smaller than 1.05λ, the cutoff wavelength falls within a spectral band extending from the center wavelength of the emission spectrum of the phosphor, which may reduce the amount of emitted light.

On the other hand, when λ0 is larger than 1.50λ, the region with large ripples in the transmission band approaches the center wavelength of the emission spectrum, and the light emitted from the phosphor is insufficiently blocked at a large emission angle. Furthermore, since the thickness of each layer of the optical interference filter increases, this is not preferable from the viewpoint of productivity. For the reasons described above, it is most preferable that λ0 be thicker than 1.10λ and smaller than 1.35λ. The phosphor used in the cathode ray tube face plate of the present invention is not particularly limited, and for example, as a green light emitter, yttrium aluminum garnet televisionram (YAG: T
b) Known phosphors such as europium-activated yttrium oxide (Y2O2:Eu) as a red light emitter and zinc silver sulfide (ZnS:Ag) as a blue light emitter can be used. Further, the face plate is not particularly limited as long as it is a known glass face plate, but an X-ray absorbing face plate is preferably used from the viewpoint of safety to the human body when displaying an image.

[Function] La2O3°CeO2,P"203 contained in the low refractive index layer and the high refractive index layer of the optical interference filter according to the present invention
Alternatively, the oxide of a lanthanoid element such as N d 20 a prevents the optical interference filter from being colored when electron beams or X-rays irradiated on the surface of the optical interference filter enter the inside of the filter. In addition, by adjusting the amount of the lanthanide-based oxide contained in the low refractive index layer and the high refractive index layer, the refractive index difference between the low refractive index layer and the high refractive index layer is adjusted, and the optical interference filter Electron beam coloring resistance and X-ray coloring resistance can be obtained without deterioration of optical properties.

[Example] This will be explained below based on examples.

FIG. 1 is a partial cross-sectional view of one embodiment of the cathode ray tube face plate of the present invention.
The optical film thickness on the inner surface is the design wavelength λ.

Low refractive index layers 2 and high refractive index layers 3, which are integral multiples of 1/4 of λ, are alternately laminated, and finally the design wavelength λ. An optical interference filter 4 is provided in which a layer with a low refractive index of 1/8 is laminated, and a phosphor layer 5 is provided on the optical interference filter 4.

Moreover, FIG. 2 shows one of the optical interference filters according to the present invention.
It is a figure which shows the spectral transmittance curve of an Example.

Example 1 A face plate of a projection type cathode ray tube with a diagonal length of 1.1 mm and a diameter of 30 mm was installed in a vacuum evaporation apparatus.
Set it in a rotating holder together with a glass plate of mm and heat it at 300℃.
While heating the inside of the vacuum chamber to [i, 7X 10-'Pa
It was evacuated. Quartz glass containing 0.3% CeO2 and
．． TlO2 sintered pellets containing 3% CeO2 were filled, oxygen was introduced into the vacuum chamber by adjusting a gas introduction valve from the outside, and the vacuum chamber was evaporated under a constant oxygen partial pressure. 0.3% Ce
4. When coating a TIO2 film (H layer) containing O2.
When coating the SiO film 2 (L layer) containing 0.3% CeO at 0.times.10.sup.-2 Pa, the oxygen partial pressure was adjusted to 1.3.times.10'Pa. Optical film thickness is approximately 165nm
The T z O2 layer (H layer) containing 0.3% CeO and the S t O2 layer (L layer) containing 0.3% CeO were coated by optical coating using monochromatic light with a wavelength of 660 r+m, respectively. Film thickness was controlled by so-called 1/4 wavelength control on a monitor.

TiO containing 0.3% CeO2 with the optical film thickness described above
layer (H layer), SiO2 containing 0.3% CeO2
By alternately coating the layers (L layers), the first method can be applied to a projection tube in which the emission center of the phosphor is 544 runs.
Sample 1 of a face plate was obtained, in which the inner surface of a display window was coated with an optical interference filter having the film configuration shown in the table. In addition, the glass plate set in the rotating holder at the same time as the face plate,
The glass plate was removed from the vacuum apparatus, and the spectral transmission characteristics of the glass plate were measured to obtain the curve (a) in FIG.

Table 1 A green phosphor was glued onto the optical interference filter of sample 1 of the cathode ray tube face plate obtained using water glass.
This cathode ray tube face plate was accelerated in a vacuum at a voltage of 30
It was irradiated with an electron beam of kV and an electron current of 6o+A for 10 minutes while scanning, and the coloring of the optical interference filter due to the electron beam irradiation was examined.

As the results are shown in Table 2, no coloring was observed even after 10 minutes of irradiation. Furthermore, a low refractive index layer (L layer)
Sample 1 was prepared by changing the material of the high refractive index layer (H layer) and the type and amount of oxide of the lanthanide element added.
Sample 2 of cathode ray tube face plate in the same manner as above.
-13 were manufactured and their resistance to electron beam coloring was examined. sample 1
Table 2 summarizes the compositions of the low refractive index layer and high refractive index layer of the optical interference filters provided in items 1 to 13 and the test results for electron beam coloring resistance. In addition, the spectral transmittance characteristics of the optical interference filters deposited on the glass plate at the same time as samples 2 and 3 of the cathode ray tube face plates are shown in Fig. 2 (b) and (c), respectively.
).

L: low refractive index layer, H: local refraction Φjso [Comparative example] In the same vacuum evaporation apparatus as in the example, a face plate of a projection type cathode ray tube with a diagonal length of a finch was set on a rotating holder, While heating to 300℃, the inside of the vacuum layer is heated to 6.7X 1
The vacuum was evacuated to 0-4 Pa, and a SiO2 film (L layer) and a TiO□ film (H layer) were placed on the inner surface of the cathode ray tube face plate at 1.3X 10-2 Pa, respectively.

4. Films shown in Table 1 deposited at an oxygen partial pressure of OX 102 Pa (cathode ray tube equipped with an optical interference filter of IX1 composition)
Comparative sample 1 of Ace plate was obtained. Furthermore, by changing the film materials of the L layer and H layer, Comparative Sample 2 was prepared in the same manner.
-5 was obtained. The optical interference filters of Comparative Samples 1 to 5 and the results of the electron beam coloring resistance test conducted in the same manner were
They are summarized in the table.

According to the above, CeO2 according to the present invention.

A cathode ray tube face plate having an optical interference filter in which any of La2O3,P'203.Nd2O3 is included in the low refractive index layer and the high refractive index layer has a lower refractive index than any of Comparative Samples 1 to 5 in which these are not included. It can be seen that the coloring does not easily deteriorate.

[Effects of the Invention] The optical interference filter of the cathode ray tube face plate of the present invention does not cause the browning phenomenon caused by the irradiated electron beam, so it can project bright images when used as a projection tube of a projection television. be able to.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view schematically showing the structure of an embodiment of an optical interference filter attached to a cathode ray tube and a face plate of the present invention, and FIG. 2 is a spectral diagram of an embodiment of the optical interference filter of the present invention. Figure 3(a) is a diagram showing the transmission characteristics, and Figure 3(a) is a diagram showing a state in which an image is being projected by a projection television. Figure 3(b) is a diagram showing the state in which an optical interference filter and phosphor are attached to the cathode ray tube face plate. FIG. 4 is a diagram showing the state in which the optical interference filter is provided, and the cutoff wavelength λ of the optical interference filter is
0 and the center wavelength λ of the emission spectrum of the phosphor. 1... Cathode ray tube face plate, 2... La2O3°CeO2, with an optical film thickness of 1/4 of the cutoff wavelength,
A low refractive index layer containing either Pr2O3 or Nd2O3,
2a...L a where the optical film thickness is 1/8 of the cutoff wavelength
OCe 02 , P r20a . 23゜Low refractive index layer containing either Nd2O3, 3...La2O3゜CeO with an optical film thickness of 1/4 of the cutoff wavelength
2, P "203. High refractive index layer containing any of Nd2O3, 4... Optical interference filter, 5... Phosphor layer, 3
1...Cathode ray tube, 32...Lens, 33...Screen. Figure 1 Figure 3

Claims (1)

[Claims] 1) Low refractive index layers and high refractive index layers are alternately laminated between a phosphor layer provided on the inner surface of the display window of the cathode ray tube face plate and the display window. In the cathode ray tube face plate provided with an optical interference filter consisting of layers, at least one of the alternately laminated layers includes La_2.
O_3, CeO_2, Pr_2O_3, Nd_2O_3
At least one selected from oxides of lanthanoid elements consisting of oxides of lanthanide elements is added and included sequentially from the layer in contact with the phosphor layer, and the refractive index of the low refractive index layer is equal to that of the high refractive index layer. A cathode ray tube face plate characterized in that the ratio to the ratio is 0.80 or less. 2) The main components of the low refractive index layer are SiO_2 and Al_2O
_3 or MgF_2, and the main components of the high refractive index layer are TiO_2, ZrO_2, Ta_2O_
5. 1 selected from the group of transparent oxides consisting of HfO_2
A cathode ray tube face plate according to claim 1, characterized in that: