JPS6012646A - Pick-up tube - Google Patents

Abstract

PURPOSE:To maintain the properties of a photoconductive film and prevent generation of a false signal while preventing the light, which reflects at an angular window mesh electrode, from influencing on the properties of the photoconductive film by coating the surface on the target side of the angular window mesh electrode with a light absorbing film. CONSTITUTION:The surface on the side of the target 3 of an angular window mesh electrode 6 in a pick-up tube provided with the angular window mesh electrode 6 is coated with a light absorbimg film 15. Thereby, even when the light incides on the angular windown mesh electrode 6 from a peripheral gap of the target 3, said incident rays 13 are prevented from inciding on a photoconductive film 12 while reflecting as shown by the broken line. Carbon or the other material, for instance, chrome oxide, low-vacuum-evaporated black platinum, black palladium, black gold or carbon can also be used for the light absorbing film 15 due to the properties having secondary electron emission and no generation of gas. Further, the thickness of the light absorbing film 15 is desirably to be about 0.1-5mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an image pickup tube equipped with a square window mesh electrode.

[Background of the invention]

Conventionally, in this type of image pickup tube, when light enters a square window mesh electrode placed between a target with a photoconductive film, such as a Saticon film, and an electron gun through a gap around the outer circumference of the target, the incident light passes through the square window. It has the disadvantage that it is reflected on the surface of the mesh electrode and reaches the photoconductive film, generating false signals. For this reason, countermeasures have been taken such as coating the side of the face plate and the contact area between the target and the bulb with a face mask and installing a mask to prevent incident light. This can be a fatal drawback, especially in broadcast image pickup tubes.

[Purpose of the invention]

The present invention was made in view of these circumstances, and its purpose is to prevent the light reflected by the square window mesh electrode from affecting the properties of the photoconductive film, and to maintain the properties of the photoconductive film. An object of the present invention is to provide an image pickup tube that can prevent the generation of false signals.

[Summary of the invention]

In order to achieve such an object, the present invention coats the target-side surface of a square window mesh electrode with a light-absorbing film. Hereinafter, the present invention will be explained in detail using Examples.

[Embodiments of the invention]

FIG. 1 is a partially sectional side view of an image pickup tube showing an embodiment of the present invention, and FIG. 2 is a partially sectional side view showing a square window mesh electrode section. In the figure, one opening of a cylindrical bulb 1 is provided with a photoconductive target 3 having a face plate 2 as a body, and the other opening has a plurality of electrode legs 4. A stem 5 is integrally provided so as to be sealed. Inside the stem 5,
An electron gun is provided. A square window mesh electrode 6 is provided near the target 3 and on the electron gun side. This square window mesh electrode 6 is composed of a mesh 1 of 1800 meshes/inch and a ring 8 for holding this mesh. One end of a mesh support electrode 9 is fixed to the ring 8, and a focusing electrode 11 is coaxially provided near the other end of the mesh support electrode 9 with an insulator 10 in between. This focusing electrode 11
A grid electrode (not shown) is provided between the electron gun and the electron gun.

In the above configuration, the electron beam emitted from the electron gun scans the top of the target 3, and the image formed on the photoconductive film 12 of the target 3 is left alone to obtain an output. The mesh support electrode 9 and the focusing electrode 11 or the accelerating electrode in the grid electrode constitute an electrostatic lens for the electron beam.

A varnish 14 is applied to the side surface of the face plate 2 and the contact area between the target 3 and the bulb 1 in order to prevent incident light 13 from that area or from around the outer surface of the face plate 2. However, as mentioned above, this becomes a problem when the amount of light transmitted through it is large.

Therefore, the surface of the square window mesh electrode 6 on the target 3 side is coated with a light absorption film 15.

With this, even if light enters the square window mesh electrode 6 from the gap around the outer periphery of the target 3, the incident light 13 can be prevented from being reflected as shown by the broken line and entering the photoconductive film 12. can. As the light absorption film 15, a carbon vapor-deposited film was used in this embodiment due to its characteristics such as no secondary electron emission and no gas emission, but other materials having similar characteristics may be used. Materials such as chromium oxide, black platinum deposited in low vacuum, black palladium, black gold or carbon may also be used. Further, the appropriate thickness of the light absorption film 15 is about 0.1 to 5 μm.

〔Effect of the invention〕

As explained above, according to the present invention, the surface of the square window mesh electrode on the target side is coated with a light absorption film, so that the light incident from the gap around the target periphery is reflected by the square window mesh electrode and enters the target. Adverse effects on the properties of the conductive film can be effectively prevented.

[Brief explanation of drawings]

It is a side view of a part. 1...Pulp, 2II...Face plate, 3
・・・Target, 5...φ-Stem, 6...φ
Corner window mesh electrode, 12... photoconductive film, 15... fist φ light absorption film. Figure 1 Figure 2

Claims (1)

[Claims] An image pickup tube equipped with a square window mesh electrode between an electron gun that emits an electron beam and a target scanned by the electron beam, characterized in that the surface of the square window mesh electrode on the target side is coated with a light absorption film. Image tube.