JPH02250242A - Cathode-ray tube - Google Patents

Abstract

PURPOSE:To provide good performance of tight contacting with fluorescent substance and accomplish an image of high quality by using an optical interfering filter having periodical stratification of layers consisting of a low refraction factor material, with the optical film thickness specified, and layers consisting of a high refraction factor material. CONSTITUTION:The film constitution of an optical interfering filter include periodic stratification 6 of layers 3 made of a material having a low refraction factor, which is approx. 0.25 times as great as the cutoff wavelength lambda0 with the optical film thickness greater than the center wavelength lambda of the emission spectrum of the fluorescent substance, and layers 2, 4 made of a material having high refraction factor, wherein the two outside located layers shall constitute the ones with low refraction factor. Between this periodic stratification 6 and fluorescent substance layer, are interposed one over another a layer 5 consisting of or chiefly containing SiO2 in an optical film thickness from the fluorescent substance layer 0.05lambda0-0.2lambda0 or 0.47lambda0Xm+ or -0.12lambda0 (m is an integer from 1 to 10), respectively, and the mentioned layer 2 with high refraction factor in an optical film thickness of approx. 0.25lambda+0.125lambda0, and another layer 2 with high refraction factor in an optical film thickness of 0.25lambda+0.125lambda0 is provided between the periodic stratification 6 and the display window inne surface. This provides good performance of tight conatcting with the fluorescent substance, less ripples in the penetrative zone, and easy controllability for the optical film thickness of each film.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a high refractive index material provided between the inner surface of a television cathode ray tube and a phosphor layer coated on the inner surface of the cathode ray tube. This invention relates to a cathode ray tube having an optical interference filter consisting of a plurality of alternating layers of a low refractive index material and a low refractive index material, and in particular to a projection type cathode ray tube that magnifies and projects an image in front of the screen onto a screen through a projection lens placed opposite to the phosphor surface. be.

[Prior Art] Display using a projection type television that displays a large image by projecting an image onto a screen involves condensing light from a projection type cathode ray tube 41 with a lens 42, as shown in Fig. 4 f8+. There are optical systems for the three primary colors of blue, green, and red, and each image is projected onto the screen 43. The projection type cathode ray tube 41 used here is a projection type cathode ray tube 8i! as shown in FIG. 4(b). 1j1 tube 4
A phosphor layer 44 is coated on the inner surface of 1, and this phosphor layer 44
An optical interference filter 45 consisting of alternating layers, such as a short bath edge filter, is provided between the projection type cathode ray tube and the inner surface of the projection type cathode ray tube. Such an optical interference filter, as shown in FIG.
slightly longer wavelength λ. An optical interference filter having a cutoff wavelength of

[Problems to be Solved by the Invention] Since water glass is used as the adhesive medium between the above-mentioned light emitter layer and the optical interference filter, the outermost layer of the optical interference filter is made of SiO□ which has good adhesion to the water glass. , or 5i02 as a main component is preferable in order to ensure practical adhesion. A short bath edge filter whose outermost layer is a layer of a low refractive index material made of SiO If H represents a layer having an optical thickness of 1/4 of the cutoff wavelength, its film structure is (L/2 HL/2
) is limited to a multilayer film with a repeating unit.The performance required for a short bath edge filter, which is coated on the inner surface of a projection cathode ray tube, is that it has good adhesion with the phosphor layer mentioned above. In addition, the transmittance is high in a band related to the wavelength of the emission spectrum of the phosphor in the transmission band, and it is transmitted in the reflection band.

It is important that the transmittance is low, and it is preferable that there is little ripple in the transmittance in the transmission band.Furthermore, the designed film structure can be used to easily control the film thickness and provide optical coverage with good workability. It is important to be able to fabricate interference filters.

However, the optical interference filter disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 61-273837, which has a repeating unit of <t, /2 Ht, /2), inherently has a large ripple in the transmission characteristic in the transmission region, and this ripple In order to prevent this, the optical thickness of each layer is determined by the cutoff wavelength λ. 1/ of
It is necessary to change it little by little from 4. Therefore, when coating a film, it is not possible to control the film thickness of each layer using the peak value of the monitored light intensity using an optical monitor, making it difficult to accurately control the film thickness to a predetermined film design value.
There is a problem in that it is difficult to manufacture optical interference filters with good workability.

[Means for solving the problem] An optical interference filter that solves the above-mentioned problems, that is, has good adhesion to the phosphor, has little ripple in the transmission region, and can easily control the optical thickness of the film. In the film configuration, the optical film thickness has a cutoff wavelength λ that is larger than the center wavelength λ of the emission spectrum of the phosphor. having periodic alternating layers in which layers of a low refractive index material and a layer of a high refractive index material, each of which is approximately 0.25 times as large as 0.0 from the phosphor layer between the periodic alternating layer and the phosphor layer
5λ. ~0.2λ. Or 0.47λ. ×m±0.1
2λ. (m is an integer between 1 and 10)
n, or a layer whose main component is SiO□, and about 0.25
λ+0.125λ. A layer of a high refractive index material having an optical thickness of 0.25λ+0.125λ is sequentially formed between the periodic alternating layer and the inner surface of the display window. A layer of high refractive index material with an optical thickness of .

The optical film thickness is the cutoff wavelength λ. A layer of a high refractive index material, which is approximately 0.25 times as large as λ, and a layer of a low refractive index material are designated H and L, respectively, and the optical film thickness is approximately 0.25 times the wavelength λ of the emission spectrum of the phosphor. A layer of high refractive index material
, the optical film thickness is 0.05λ. ~0.2λ. Or 0.4
7λ. ×m±0.12λ.

(m is an integer from 1 to 10) 5ift or Sin
If the layer containing g as a main component is represented by L, then the state in which the optical interference filter according to the present invention is bonded to the phosphor layer can be expressed by equation (1).

Phosphor layer/L'H' (H/2) (LH)K L ()
I/2) H'/inner surface of display window <11
Here, k is an integer representing the repetition of a pair of layers L and H.

Equation (1) is the cutoff wavelength λ. For a layer whose optical thickness is 0.25 times that of (I(/2 L H/2)
is understood to have a basic repeating structure. When k is less than 1, that is, the number of periodic alternating layers is less than 3, the cutoff wavelength λ. The cutoff characteristic of the transmittance in the phosphor becomes less sensitive, the cutoff characteristic with respect to the angle of light emitted from the phosphor deteriorates, and the transmittance in the reflection band becomes higher. If k is larger than 9, that is, if the number of periodic alternating layers is larger than 19 layers, the optical cutoff characteristics of the optical interference filter, the transmittance in the transmission band, the ripple, and other characteristics will be improved, but it will be difficult to manufacture the optical interference filter. This takes a lot of time and requires more precise control of the film thickness and refractive index of the film, which reduces the reproducibility of manufacturing the optical interference filter. Therefore, the number of periodic alternating layers having an optical thickness 0.25 times the cutoff wavelength λ0 of the optical interference filter according to the present invention is preferably 3 to 19 layers, most preferably 9 to 17 layers.

The center wavelength λ of the emission spectrum and the cutoff wavelength λ serving as the design standard for the periodic alternating layer. The relationship is λ.

is preferably larger than 1.10λ and smaller than 1.50λ, and furthermore, λ. is greater than 1.10λ and 1.3
Most preferably, it is less than 5λ. λ. When is smaller than 1.10, 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, λ. When 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.

SiO□ or 5i02 provided facing the phosphor layer
If the optical thickness of the layer containing as a main component is out of the above range, the transmittance in the transmission band will be significantly reduced.

Therefore 0,05λ. ~0.2λ. Or 0.47
The working time is preferably within the range of λoXm±0.12λo (m is an integer greater than or equal to 1 and less than or equal to IO).

Considering optical properties and adhesion, especially 0.4λ. ~0.
5λ. A range of is preferred. Here, the layer containing Sing as a main component is preferably a glassy layer, and the glass composition is Corning Co., Ltd. 9068.
, RCA G999, or the like.

Further, materials that can be used as high refractive index materials according to the present invention are those that form a film with a refractive index of 1.8 or more in the visible range.
2゜5nOz, PrTiO3, InzOa + Zn
A film made of one or a mixture of at least two selected from the group consisting of O is preferable, and a film of Ti(h) is most preferable. Preferably, from the viewpoint of ensuring good durability of the obtained optical filter, Sing
Most preferably 0, the optical interference filter of the present invention is 1/4
The coating material is deposited on the inner surface of the heated projection cathode ray tube using a vacuum evaporation method using an electron beam heating method using a vacuum evaporation device equipped with a normal optical monitor to control the optical film thickness of the wavelength, or by a sputtering method. It can be manufactured.

[Function] The periodic alternating layers having a basic repeating structure of (H/2 L H/2) according to the present invention provide selective transmittance to wavelengths of light due to the interference effect of light, and also reduce the amount of light emitted from the light emitter. give directionality to. A layer H made of a high refractive index material provided on both outer sides of this alternating layer acts to reduce ripple in the transmission band, and is provided facing the phosphor layer with SiO□ or SiO! The layer containing as a main component has the effect of improving adhesion when bonding the phosphor layer and the optical interference filter with water glass without deteriorating the optical properties of the optical interference filter.

[Example] A projection cathode ray tube face plate with a diagonal length of 1.1 fins and a diameter of 30 mm was placed in a vacuum evaporation apparatus.
Set it in a rotating holder together with the fl glass plate and heat it to 300℃.
While heating the inside of the vacuum chamber to 6,7
was evacuated. Different water-cooled crucibles for electron beam heating were filled with granular quartz glass and Ti(h) sintered pellets, and oxygen was introduced into the vacuum chamber by adjusting the gas introduction valve from the outside under a constant oxygen partial pressure. Vapor deposited.TiO2
4. When coating the membrane. OX 10-”Pa, Si
When coating the 0g film, the oxygen partial pressure was adjusted to 1.3 x 10-''Pa.

TiO,lii CH layer with optical film thickness of 165 m) and 5t (hlli (Lli), optical film with 136 m
The coating thickness of the ru++(7)TtOJi (H' layer) was controlled by so-called 174 wavelength control of an optical monitor using monochromatic light with wavelengths of 660 fins and 544 fins, respectively. Ti01 layer (1/
2H layer), the film thickness was determined from the transmittance curve recorded during vapor deposition on an optical monitor using monochromatic light with a wavelength of 660 nm.

In addition, the optical thickness of the last 5 inf layer of 285.5 fins is:
The experiment was performed based on 174 wavelength control using monochromatic light with a wavelength of 660 nm. Tioz layer with the optical thickness described above, 5i (
By alternately coating the h layers, an optical filter having the film configuration shown in Table 1, which can be applied to a projection tube in which the emission center of the phosphor is 544nn+, was created. The glass plate set on the rotary holder at the same time as the face plate was removed from the vacuum apparatus, and the spectral transmission characteristics of the glass plate were measured to obtain the broken line shown in FIG.

Table 1 [Comparative Example] A face plate of a projection type cathode ray tube with a diagonal length of 1/2 inch was placed in the same vacuum evaporation apparatus as in the example.
, set it in a rotating holder together with a glass plate with a diameter of 30 m,
While heating to 300℃, the inside of the vacuum chamber was heated to 6.7 x 10
-'Pa, and the Sin, membrane and Tioz films were each evacuated to 1.3 X 10-''Pa, 4.OX 1
Vapor deposition was carried out at an oxygen partial pressure of 0-''Pa to obtain samples with the film configurations shown in Table 2.Here, the optical thickness of the SiO□ film and the Ti0z film was set to 165 mm, which is the thickness of 1/4 wavelength. Than,
As shown in Table 1, it was small at the center of the layer and increased toward both ends of the layer. The spectral transmittance of the obtained glass plate is shown by the solid line in FIG.

Moreover, the solid line in FIG. 3 shows the dependence of the transmittance on the angle of incidence when monochromatic light with a wavelength of 544 nm is incident on the optical interference filter obtained in the example, and the broken line in FIG. The characteristics of an optical interference filter are shown.

From FIG. 3, it can be seen that the optical interference filter according to the present invention has better dependence of transmittance on the angle of incidence.

54 in the normal direction to the display window surface for the above projection tube.
Table 3 shows the results of irradiating with 4 nm monochromatic light and measuring the real bulb brightness, as well as the results of examining the coatability of the phosphor.

It can be seen from Table 3 that the projection tube having the optical interference filter according to the present invention can obtain high brightness and has good phosphor coating properties.

The phosphor is blue (center wavelength of emission is 450rv, for example)
If the cutoff wavelength is 540nm, the phosphor is red (
For example, if the center wavelength of light emission is 612 nm),
By setting the cutoff wavelength to 740 nm, and coating the inner surface of the projection tube for blue or red light with an optical interference filter in the same manner as in the above embodiment, optical interference can be applied to the projection tubes for each of the three primary colors. You can get filters.

[Effects of the Invention] The cathode ray tube provided with the improved optical interference filter according to the present invention can extract a large amount of luminance from the phosphor, so when used as a projection tube, it is possible to obtain a bright image. I can do it.

In addition, the optical interference filter provided is made of phosphor and SiO□
Or, since it is in contact with a layer mainly composed of SfO□, it has good adhesion with the phosphor and produces fewer pinholes.
High quality images can be obtained. Furthermore, when creating an optical interference filter, it is easy to work with, so it can be manufactured efficiently.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view schematically showing the optical interference filter according to the present invention, FIG. 2 is a diagram showing the transmission characteristics of the optical interference filter of the present invention and a conventional optical interference filter, and FIG. A diagram showing the dependence of the transmittance of the optical interference filter of the invention and the conventional optical interference filter on the angle of incident light. FIG. 4 shows a state in which the optical interference filter is installed in a projection tube and an image is projected by a projection television. FIG. 1...Cathode ray tube, 2...Optical film thickness is approximately 0.25λ
+0, 125λ. A layer of high refractive index material, 3...optical film thickness is approximately 0.25λ. A layer made of a low refractive index material, 4...The optical thickness is approximately 0.25λ. A layer made of a high refractive index material, 5... A layer containing 5iyx or SiO□ as a main component, 6... Periodic alternating layers, 7... Optical interference filter, 41... Cathode ray tube, 42... ··lens,
43. ... Screen, 44 ... Phosphor layer, 45.
...Optical interference filter. Figure Wave input λO length (nm) Fifth factor

Claims (1)

[Claims] 1) Between the phosphor layer provided on the inner surface of the display window of the cathode ray tube and the display window, a layer of alternating layers of a high refractive index material and a layer of a low refractive index material is formed. In a cathode ray tube provided with an optical interference filter, the alternating layers a) have an optical film thickness approximately 0.25 times the cutoff wavelength λ_0, which is larger than the center wavelength λ of the emission spectrum of the phosphor; b) periodic alternating layers consisting of at least three layers, the outer layer of which is a layer of a low refractive index material; and b) 0.05λ_0 provided between the periodic alternating layers and the phosphor layer in order from the phosphor layer side. SiO_2 or SiO with an optical thickness of ~0.2λ_0 or 0.47λ_0×m±0.12λ_0 (m is an integer from 1 to 10)
A layer mainly composed of _2 and approximately 0.25λ+0.1
c) two layers of high refractive index material with an optical thickness of approximately 0.25λ + 0.125λ_0 between the periodic alternating layers and the inner surface of the display window; 2) The cutoff wavelength λ_0 of the optical interference filter is 1.
10λ<λ_0<1.50λ 3) The cathode ray tube according to claim 1 or 2, wherein the number of periodic alternating layers is 3 to 19. The layer of high refractive index material is TiO_2, Ta_2O_5
, ZrO_2, HfO_2, SnO_2, PrTiO_
3. One or a mixture of at least two selected from the group consisting of In_2O_3, and the layer of the low refractive index material is SiO_2 or MgF_2. Cathode ray tube mentioned