JPS59139534A - Face plate of image pick up tube - Google Patents

Abstract

PURPOSE:To restrict the reduction of yield rate due to a surface defect and to improve a picture image characteristic by forming a transparent conductive film formed upon an optically transmissive thin film glass on a filter with solid solution of a predetermined thickness consisting of In2O3 and SnO2. CONSTITUTION:Width 300-1,000Angstrom or 1,800-2,600Angstrom at the bottom of a spectroscopic transparency rate shown in a diagram representing a film thickness vs. transparency rate of a transparent conductive film material consisting of In2O3 and SnO2 in a visual light range is determined to obtain a film thickness proper to a transparent conductive film. Upon a thin plate glass 14, a transparent, conductive film In2O3-SnO2 spattered film 15 of a resistance value being not more than 5kOMEGA/unit area is formed in attached status at a temperature not burning an organic filter, an optically conductive film 16 is attached on it, and preferably a cleaning process is interposed in a forming process and forming is performed at least more than two times dividedly. Accordingly, the reduction of yield rate due to surface defect can be restricted, a good resistance value as for a photo-electric converting element is given, and a picture image property is improved as the surface ruggedness can be made small.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a face plate for a color television image pickup tube, and more particularly to a face plate for an image pickup tube having a color separation filter on the face plate.

In general, a color television camera obtains three color signals of green, blue, and red, and requires one image pickup tube for each color, so it is safe to use three image pickup tubes. Recently, multicolor image pickup tubes or single-tube color image pickup tubes have been developed that can extract two or three color signals using a single image pickup tube.

FIG. 1 is a sectional view of the holder showing an example of this conventional multicolor image pickup tube, and FIG. 2 is a sectional view of the holder showing an example of its face plate structure. In these figures, this image pickup tube has a color separation stripe filter (hereinafter referred to as a color separation filter) 2 on the surface of a face plate 1 (transparent substrate) made of a transparent glass material.
, a grooved glass plate 4, a transparent conductive film 5, and a photoconductive film 6 are sequentially adhered via an adhesive 3, and this face plate 1 is coated with an indium 7
Using a signal type fi8 with a
It is constructed with care. Then, light 1 from subject 11
2 is imaged on the photoconductive film 6 through the optical lens 13, and the charge pattern image corresponding to the image of the subject 11 is formed on the photoconductive film 6.
The electron beam 14 from the electron gun 9 is formed on the outer tube 1.
1 corpse facing coil 15 arranged around the outer circumference of 0, focusing coil 1
The magnetic field created by the photoconductive film 6 focuses and scans the bottom surface of the photoconductive film 6, converting the charge pattern into a current, which is extracted from the signal current 8 through the transparent conductive film 5 and the indium 7 as an electrical signal.

To describe the manufacturing process of this face plate for an image pickup tube, as shown in FIG. A color separation filter 2 is deposited, and a transparent conductive film 1) (CV D Sn 02 Nesa film) is applied on it to a film thickness of 11
A thin plate glass 4 having a thickness of about 30 .mu.m and having a thickness of 00 to 1500 A is adhered thereto using an adhesive 3 (3' also indicates an adhesive), and a photoconductive film 6 is further adhered thereon. This manufacturing method uses Cvv membrane, which has a large thickness and leaves stains and white dust even after cleaning after liquid collection, and chemical etching of only the Nesa membrane is impossible, so the only option is to regenerate the color separation filter. These drawbacks have led to a significant increase in the manufacturing cost of image pickup tubes.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a face plate for an image pickup tube that is inexpensive and has good image quality.

The non-invention for achieving the above purpose is to
The transparent conductive film is made of 203 and SnO2 and has a thickness of either 300 to 1000λ or 1800 to 2600λ.

The transparent conductive film of the present invention having the above structure was discovered through the results of research and experiments described below. That is, the above ■n203 in the visible light region (λ-450 to 600 nm)
When we measured the film thickness-biweekly rate characteristics of a transparent conductive film material consisting of
1200 to 160 corresponding to peak 52 and its vicinity
Two ranges were shown: 0 and 2,500 to 3,200. However, this is the case where light transmission is through two layers of glass and a transparent conductive film, and when it comes to three layers of glass, transparent conductive film, and photoconductive film, light transmission takes on a more complicated aspect. In particular, as in the present invention, the refractive conductors 1,6 to 2.4 of the implicit conductive film 5
Therefore, if the refractive index of the Se-based amorphous photoconductive film 6 with a thickness of 1 to 2 μIn formed above is larger, the 1-minute transmittance is reversed as described below. The opposite is true (not shown). That is, the transparent conductivity 'fM, the peak of the spectral transmittance of the film (
The peak) becomes the valley of the spectral sensitivity, and therefore, the optimum film thickness of the transparent conductive film is different from the value corresponding to the film thickness of the first and second peaks 51. Thickness 300~
The film thickness of 1,000 or 1,800 to 2,600 is most suitable for a transparent conductive film. The relationship between the film thickness and the resistance value in both film thickness ranges is shown in Figure 6.
, the latter being 35 to 60 Ω7/, which is a sufficiently satisfactory value as a photoelectric conversion element, and it was confirmed that a stable and high-quality image pattern could be provided. The present invention particularly focuses on waves f 5
It showed good light resistance for 50 nm blue light. This is a fundamentally different way of thinking, whereas in the past, only the optimal value of transmittance was followed and the film thickness was increased, or only the spectral transmittance of the transparent conductive film was followed (thus, the direction f was determined to determine the film thickness). It can be said to be groundbreaking as it required a correction.

The light transmittance will be explained in detail below.

Now, assuming that the refractive index of glass is n1, the refractive index of the transparent conductive film is nl, and the refractive index of the photoconductive film is O2, the light transmittance T is expressed by the following formula.

2π (however, δ−2" (mouth, d) d; transparent conductive film thickness) glass,
The refractive index n of each of the transparent conductive film and the photoconductive film. ='1.
47. n,=2.0. n2=2.95 (: then s n
Since the relationship is o<nl<O2, the third song in the denominator of the above equation takes a positive value. On the other hand, in the case of the two-layer structure without the photoconductive film mentioned above, it is thought that air has replaced the photoconductive film.
The refractive index n2=1.0, and the relationship O2<no<n is established. As a result, the third term in the denominator of the above equation takes a negative value. Since these third terms in the denominator are related to the trigonometric function cos, the light transmittance for each wavelength has a periodicity of 1υ, and the periodicity of the light transmittance is reversed by the third term in the denominator. Therefore,
If you plot the light transmittance for each wave length λ in sequence, it will be clear that the peak value in the case of two layers corresponds to the position of the trough in the case of three layers including the photoconductive film. .

Next, this manufacturing process is shown in FIG. 4.

The rest in the manufacturing method is (1) 8 samples for forming a transparent conductive film.
Cooling to below 0°C and using sputtering method, (2
) More preferably, the step of forming the transparent conductive film is performed in at least two steps with a cleaning step inserted in the middle. A thin plate glass 14 of about 50 μm is glued onto the face plate 11 on which the color separation filter 12 (in this case, an inexpensive organic filter with good spectral transmittance characteristics is attached) is adhered, and then the adhesive 13 is The total thickness of the thin glass sheets 14 is approximately 30 μm (the thickness of the adhesive is approximately 6 μm, the thickness of the 4 glass sheets is approximately 2
Polish to a thickness of 4 μm) and wash. Next, the temperature at which the organic filter does not burn out on the thin glass (face plate stiffness temperature 1
Transparent conductive film I n 2 with a resistance value of 5 to 27 or less (if the resistance value exceeds 5 to 27, smearing defects of the pattern image will occur and it will become unusable) at 40°C, lhr or less)
03-8n O2 sputtered film 15 is deposited, and photoconductive film 16 is deposited thereon. Compared to the conventional method of forming CVI) films using this manufacturing method, ■n203-
With the 8nO2 sputtered film, there were almost no stains or white scratches after cleaning, and the yield of surface defects on the tube improved from 10% or less to 75%. The face plate surface temperature was 60°C or less, and the resistance value was reduced by more than an order of magnitude. Furthermore, since chemical etching of only the sputtered I203-8nO2 film can be easily performed, the color separation filter can be regenerated, resulting in a significant reduction in manufacturing costs.

In addition, in the above-described process of forming the transparent conductive film 15 of the present invention, a cleaning process was performed after forming the transparent conductive film 15 to about half the thickness, and then the remaining half of the film thickness was formed. By using this method, the yield of the conventional process of removing pinholes caused by scratches, dirt, etc. was improved. This April, even if there is a defect in the membrane due to the initial cleaning, it will be removed in the next two cleanings, or the second high-quality 7,1' membrane (this will cover the defective membrane). In addition, the transparent conductive film in the present invention is an S n 02 film (NESA film) I formed by the conventional CV I) method.
Compared to this, the unevenness on the surface is about 1/10 smaller, so an image pickup tube with improved image quality can be obtained.

Example 1 The samples used for the invention had sizes of approximately 2/3 inch φ and 1 inch φ, and thicknesses of approximately 1.7 mm t and approximately 2.5 mm t.
A color separation filter 12 is attached on the face plate 11 in the form of a stripe, and a micro sheet glass 14 of about 50 μm is adhered thereon, and then the micro sheet glass is bonded to a thickness of about 30 μm including the adhesive 13. A transparent conductive film 15 was formed on the polished and cleaned sample at a low temperature (approximately 60° C. or lower). The conditions for creating the transparent conductive film are the usual 2
A polar high-frequency sputtering device was used. The sample was placed on the substrate holder (heated), and the substrate holder was water-cooled to cool it from the bottom of the sample.
A solid solution of mol %) was used. Inter-electrode spacing is 30-60m
100% Ar gas was used as the inert gas, and the Ar gas pressure was 5.1 x 10' Torr ~ 5. OX1O-
The sputtering power of 3 Torr is due to heat dissipation by sputtering (100 Watt (0,55 Watt
/Cm2). The sputtering time is 30 minutes for grease grasshopper.
After performing the main sputtering for 45 minutes, the film thickness was 2200±200.
It's a person. The spectral transmittance characteristics of the obtained transparent conductive film exhibit a trough pattern at a wavelength of 550 nm. Surface resistance is approximately 40-50Ω
/ It is. The surface condition (irregularities) of the film is approximately 1/10 smoother than that of the conventional 5n02 Nesa film. Finally, a photoconductive film 16 was formed on the transparent conductive film 15.

As explained above, according to the present invention, when creating a transparent conductive film at low temperature (below 140"C), ■r+203-8n
It is optimal to create O2 in two batches, without deteriorating the spectral transmittance characteristics of the color separation filter, and with a resistance value of 100Ω.
/ The optimal condition for the following film thickness is 1,800 to 2,600 people.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view showing an example of a conventional multicolor image pickup tube;
The figure is a sectional view of the face plate structure, FIG. 3 is a conventional image pickup tube face plate manufacturing process diagram, and FIG. 4 is an image pickup tube face plate manufacturing process diagram of the present invention.
FIG. 5 is a variation curve diagram of spectral transmittance depending on film thickness, and FIG. 6 is a characteristic curve diagram showing the relationship between film thickness and resistance value of the transparent conductive film used in the present invention. 11... Face plate, 12... Color separation filter, 13... Adhesive, 14... Thin glass, 15... Transparent conductive film%
16...Photoconductive film. Hair 1 Fig. 2 Fig. 3 Fig. - Fig. 5 + Fig. 5

Claims (1)

[Claims] In an image pickup tube face plate having at least a color separation stripe filter made of an organic material, a transparent thin film glass formed on the filter, and a transparent conductive film formed on the glass, the transparent conductive film is made of indium oxide. A face plate for an image pickup tube, characterized in that the face plate is formed of a solid solution of tin oxide and stannic oxide, and has a film thickness of either 300 to 1000 λ or 1800 to 2600 λ.