JPH0747789Y2 - Image Intensifia - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used in the field of photomultiplier tubes.

The present invention relates to an image intensifier, and more particularly to the structure of a cylindrical glass vacuum container.

[Prior Art] An image intensifier or an image tube is a cylindrical glass vacuum container, an input side cathode photocathode formed on one side of the container for emitting photoelectrons, and an anode formed on the bottom side of the other side container. The output side fluorescent screen and the electron lens of the electrode inside the container for accelerating and focusing the emitted photoelectrons are used to convert the accelerated and focused photoelectrons into visible light by the output fluorescent screen.

By the way, the vacuum tube is made of an insulating material such as glass, and in an image tube in which a metal film is formed inside the container by vapor deposition or the like to serve as a focusing electrode, the voltage applied to this electrode is applied. As a result, electric charges are induced on the outer surfaces of the glass container which face each other, and discharge on the surface and local concentration of electric charges affect the internal electron lens, resulting in an unstable output image. Therefore, conventionally, a conductive film is formed on the entire outer wall of the glass container to prevent electric charges from concentrating.

[Problems to be Solved by the Invention] The inner electrode of the vacuum container and the insulating portion such as glass sandwiched between the outer conductive films have a considerably large charge capacity component (to several μΩ) throughout. Therefore, when a voltage is applied, an excessive current exceeding the rating flows, and the heat generated at this time evaporates and destroys the contact point with the internal metal film, resulting in poor conduction.

Further, when the electrode voltage is changed, the response becomes poor, which causes deterioration of the performance of the device.

An object of the present invention is to provide an image intensifier having a glass vacuum container in which excessive charge concentration or local charge concentration is avoided on the outer wall.

[Means for Solving the Problems] The above-mentioned objects are: a cylindrical glass vacuum container, an input-side cathode photocathode for emitting photoelectrons formed on one side of the container, and an anode formed on the bottom of the other-side container. An image intensifier that consists of an output side phosphor screen and a focusing electrode inside the container that accelerates and focuses the emitted photoelectrons, and converts the accelerated and focused photoelectrons into visible light by the output phosphor screen. This is achieved by forming a conductive film on the outer wall surface of the container facing the above and setting the overlapping portion of the conductive film and the electrodes on both sides of the gap to be 10 mm or less.

In this way, the reason why the overlapping portion is set to 10 mm or less is that if the thickness is 10 mm or more, the deterioration of responsiveness exceeds the allowable range due to the increase in capacitance, and the external conductive film forming work for the overlapping portion is performed in the container. It is easy because the glass is transparent.

[Function] The conductive film formed on the outer wall of the glass vacuum container is divided into a plurality of blocks, and preferably the outer conductive film is formed only on the minimum necessary portion, that is, the portion where the induced charge affects the internal electron lens. To do.

Since the overlapping part of the electrode created inside the glass vacuum container and the conductive film on the outer wall is 1/5 to 1/4, which is very small compared to the conventional one, the capacitance induced by this is The components can be reduced proportionally.

Embodiment A preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a front half sectional view showing the first embodiment.

In this drawing, 5 is a glass vacuum container, and the lower surface side thereof is an input surface, which is connected to the photocathode 1. Reference numeral 2 is a focusing electrode or focus electrode for accelerating and focusing the electrons emitted from the photocathode 1, and 3 is an electrode formed on the inner wall of the glass container for the same purpose, which is composed of a metal film. In addition, 4 is an anode and 6 is an output surface made of a phosphor screen.

Regarding such in-container electrodes 1, 2, 3 and 4, a conductive film 5a is formed on the outer wall portion of the glass container 5 corresponding to the gap between the photocathode 1 and the focusing electrode 2 in FIG. It is preferable that the film 5a is formed to have a width (w) wider than the gap by about 10 mm.

Similarly, the conductive film 5b forms a gap between the electrodes 2 and 3 and the conductive film 5c.
Are formed so as to cover the gaps between the electrodes 3 and 4, respectively.

Each conductive film 5a, 5b, 5c is grounded but not shown.

In this way, when forming a conductive film on the outer surface of the container facing each electrode created on the inner wall of a vacuum container such as glass, the overlapping part with the internal electrode is wider than the end part of the electrode by about 10 mm. It is preferable to control

Further, the conductive film is formed also in the portion where the photocathode is directly observed from the container wall, and the conductive film is not formed in other portions.

The divided conductive films may be connected to each other by a linear conductive film or a conductive wire so that they have the same potential.

Further, the division of the conductive film is not limited to the block type as shown in FIG. 1, but may be the stripe shape 5d as shown in FIG. 2 or the mesh shape 5e as shown in FIG.

[Effect] Since the conductive film portion of the surface of the container (glass or the like) facing the electrode formed on the inner wall of the vacuum container is small, the capacitance component induced is about 1/5 to 1/4 of the conventional value.

Since the capacitance component is small, the response to changes in the electrode voltage is improved. In addition, the rush voltage when the power is turned on can be suppressed low.

[Brief description of drawings]

FIG. 1 is a front half sectional view showing an embodiment of the present invention, and FIG.
FIG. 3 is a front view showing another embodiment, and FIG. 3 is a front view showing still another embodiment. 1 is a photocathode, 2 is a focusing electrode, 3 is a vapor deposition electrode, 4 is an anode, 5 is a vacuum container, and 6 is an output surface.

Claims (1)

[Scope of utility model registration request] 1. A cylindrical glass vacuum container, and an input-side cathode photocathode formed on one side of the container for emitting photoelectrons.
An image in which the output side phosphor screen in the anode formed on the bottom surface of the other side container and the focusing electrode in the container that accelerates and focuses the emitted photoelectrons are converted into visible light by the output phosphor screen. In Tenshifia,
An image is characterized in that a conductive film is formed on the outer wall surface of the container facing the gap between the electrodes, and the overlapping portions of the conductive film and the electrodes on both sides of the gap are 10 mm or less at both ends. Intensifia.