JPS5832458B2 - Face plate for image pickup tube with stripe filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of an image pickup tube with a built-in stripe filter for a color television camera using a single image pickup tube system.

There are many types of image pickup tubes with built-in striped filters, but they require that the striped filter for color beam modulation and the photoelectric conversion surface are in close optical contact.

In order to obtain substantial adhesion and avoid chemical and geometric influences between the stripe filter and the photoelectric conversion surface or transparent conductive film, an inorganic transparent material layer may be formed on the stripe filter to smooth it, or A method has been adopted in which a thin glass plate is attached and a transparent conductive film and photoelectric conversion surface are formed on the surface.

In the present invention, a thin glass plate is attached using an adhesive as a protective smoothing layer on the surface of such a striped filter, and then the thin glass plate is further made thinner by polishing to further improve optical adhesion. It is.

The present inventors have proposed attaching a relatively easy-to-handle thin glass plate of about 50 to 100 μm to the surface of the stripe filter, and then polishing the thin glass plate to a thickness of about 20 to 30 μm. .

An example of this is shown in FIG. In Fig. 1, a stripe filter is generally formed on a glass substrate 1 of about 1.5 to 2.5 degrees, and if the stripe filter 2 is made of organic material, it should be exposed inside the vacuum tube as a constituent material of the vacuum tube. Because the vapor pressure is too high and the gas pressure inside the vacuum tube becomes high, making it unsuitable for operation, and in the case of an inorganic filter such as a dichroic, a transparent conductive film or a transparent conductive film is coated on the uneven structure of about 1μ to 2.5μ. The purpose of forming a photoelectric conversion surface is to prevent a signal from being generated due to the presence of the stripe filter even in the absence of imaging light, or from occurring during long-term operation. For example, a thin plate glass 3 with a thickness of about 50 to 100 microns, called Microsheet (trade name), is bonded using a solvent-free adhesive 4 such as epoxy resin.

In general-purpose single-tube camera image pickup tubes with a face plate diameter of about 26 mm to 18 mπ, the width of the stripe filter is about 30 μm, and photoelectric conversion by the imaging light that passes through the imaging lens of the stripe filter. The image projected onto the surface will be blurred.

In order to prevent this, the attached thin plate glass is polished to a thickness of about 20 to 30 μm so that the blur becomes tolerable.

According to this method, the thin plate glass is attached parallel to the surface of the striped filter, and polishing only needs to proceed parallel to the bonded surface. In order to polish efficiently, when polishing is performed using a soft polishing disk made of felt or artificial leather, the polishing of the peripheral area, which is usually referred to as peripheral sagging and shown by the dotted line in Figure 1, proceeds quickly.

Therefore, when polishing the transparent body of this structure, the thin glass around the periphery becomes abnormally thin and easily damaged, or in severe cases, the thin glass disappears and the adhesive layer is exposed, defeating the purpose of surface protection. You will not be able to achieve it.

In order to prevent this, the present invention is designed to maintain a sufficient thickness of the thin glass in the peripheral area even if the polishing method described above is applied.

The present invention will be explained below using FIG. 2.

In addition, in FIG. 2, the same parts as in FIG. 1 are indicated using the same symbols.

It has been found that the thin plate glass 3 of about 50 to 100 μm can be easily bent by a slight external force, and in some cases, it can be bent in a shape along the surface to be bonded and bonded.

In FIG. 2, excluding the filter forming part of the glass substrate 1 on which the stripe filter 2 is formed, the ineffective area as a peripheral imaging surface is lowered by a distance a, and then the thin glass plate 3 is attached, as shown in the figure. The thin glass 3 can be bent along the shape of the substrate and attached so that the peripheral part is lowered.

As the gluing method, it is easy to complete such a shape by using the centrifugal adhesion method proposed by the present inventors.

That is, the glass substrate 1 with a stripe filter is fixed on the rotating shaft, the adhesive is dropped, and then the thin glass 3 is placed so that no air bubbles are introduced into the adhesive, and the adhesive 4 is applied by the weight of the thin glass 3 or other auxiliary means. After waiting for the adhesive to spread over the entire surface, the object to be adhered is rotated at high speed, and the adhesive 4 is spread thinly by centrifugal force and fixed.

By this method, it is possible to effectively bring the peripheral thin glass 3 as close to the substrate glass 1 as possible.

If polishing is performed after the adhesive 4 has solidified, even if the polishing is performed with peripheral sagging as shown by the dotted line, the thin glass 3 at the periphery will not become abnormally thin, and in fact can be made thicker than the central portion. The striped filter face plate with a strong protective glass can be used to protect the filter.

The value of the step a in FIG. 2 is 5 μm to 20 μm for the 27-capacity tube.

It is desirable that the width of the step be as wide as possible without damaging the effective imaging surface.

Furthermore, it has been confirmed that even if the board is not divided by clear steps as shown in Fig. 2, but has a gently sloped periphery, that is, a convex center, the thin plate can be effectively bent by adhesion. Ta.

However, depending on the degree of convexity over the entire surface, it may impair the accuracy of photo processing when forming a stripe filter.

For this purpose, it is desirable that at least the peripheral imaging ineffective portion is formed lower than the effective portion and the peripheral end portion is lower by the above-mentioned 5 to 20 μm.

The easiest way to form this step is to selectively etch the corresponding part of the stripe filter forming substrate, but of course, it is also possible to raise the central imaging area using methods such as vacuum evaporation, sputtering, and low melting point glass welding. There is no problem in forming the step, and if necessary, after forming the step using a drawing method, the surface should be polished to smooth the surface and remove roughness on the formed surface.

As explained above, the present invention has an excellent effect in that a face plate with a stronger protective glass can be easily obtained compared to the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an example of a conventional face plate, and FIG. 2 is a sectional view of a main part of an embodiment of a face plate according to the present invention. 1... Glass substrate, 2... Stripe filter, 3... Thin glass, 4... Adhesive.

Claims (1)

[Claims] 1. In a face plate for an image pickup tube with a built-in stripe filter for color separation, the stripe filter forming part is made to protrude 5 to 20 μm from the peripheral part of the face plate, and a thin glass plate is adhered to the stripe filter forming surface, and the thin glass plate is not bonded. A face plate for an image pickup tube with a stripe filter, characterized in that the face side is polished.