JPS585319Y2 - image tube - Google Patents

Description

[Detailed explanation of the invention] This invention relates to an image tube, which effectively suppresses secondary electrons generated when stray electrons in the X-ray image tube are accelerated and impact the anode, etc., and increases the dielectric strength. , concerning an image tube with stable operation.

Generally, an X-ray image tube has an input phosphor surface and a photocathode, an output phosphor surface located opposite to the manually operated phosphor surface, and an input photocathode located near the tube wall. It consists of a focusing electrode that accelerates and focuses photoelectrons emitted from the auxiliary anode, an auxiliary anode, an anode, and a tube that houses them. A power supply is installed between the input luminescent surface and the anode, and between the focusing electrode and the auxiliary anode. Accelerating and focusing voltages are respectively supplied.

With the above configuration, stray electrons generated within the tube are accelerated at the anode potential, impact a high voltage application electrode such as an auxiliary anode, and generate secondary electrons.

Because a positive accelerating voltage is applied to the anode, the secondary electrons emitted from the auxiliary anode are accelerated and stimulate the output fluorescent surface, reducing the quality of the output image and lowering the potential of the electrode. It makes the image tube unstable.

As a phantom measure, at least the surface of the auxiliary anode facing the manually-powered fluorescent surface is made of a material with a small secondary electron gain (secondary electron emission ability) δ.

However, in conventional variable field of view image tubes,
Examples of materials with small secondary electron gain δ include aluminum,
Since the method of using beryllium and lithium and vapor depositing these metals on the electrode material has been exclusively adopted, it requires fairly expensive vapor deposition equipment during production and requires complicated processes for pre-treatment of the bare metal. There was a drawback.

Furthermore, it was not easy to recycle and use it.

This idea solves the above problems by diluting chromium oxide powder with resin into an ink solution, diluting it with a solvent, applying it as ink to the electrodes and the inner surface of the tube, and baking it.

The drawings will be explained below.

FIG. 1 is a cross-sectional view of the image tube of the present invention, in which 1 is an input fluorescent surface and a photocathode, 2 is an output fluorescent surface provided opposite to 1, 3 is an anode, 4 is an auxiliary anode, Reference numerals 5 and 6 designate focusing electrodes arranged near the tube wall to accelerate and focus photoelectrons emitted from the input fluorescent surface 1.

These parts within the bulb are housed in the bulb 16, and a Calorie voltage and a focusing voltage are supplied from a power supply between the input luminescent surface 1 and the anode 3 and between the focusing electrode 5.6 and the auxiliary anode 4. ing.

Note that 15 is the incident direction of the X-rays.

Under such a potential distribution within the bulb, the bending points 7 and 8 of the bulb 16 near the anode 3 and the focusing electrodes 5 and 6
The stray electrons whose generation points are the specific points 9 and 10 above impact the anode 3 and the auxiliary anode 4 along the trajectories shown by the dotted line and the dashed-dotted line in FIG. This is clear from calculation.

First, stray electron generating points 7, 8, 9, and 10 in the tube 16 were coated with chromium oxide I.

8.11, 1:2 to eliminate the source of stray electrons, and also apply chromium oxide coating13.14 to the surfaces of parts that are subject to the impact of stray electrons, such as the anode and auxiliary anode, to prevent secondary emissions caused by stray electrons. It is designed to suppress the generation of electrons and ions.

The method of suppressing the generation of stray electrons and the method of preventing the generation of secondary electrons and ions are effective even if they are implemented individually.

Next, the coating method will be explained.

First, chromium oxide powder and di-phenyl oxide resin are placed in a grinder, and while toluene is mixed in as a solvent, the powder is crushed and ground while avoiding stickiness.

In this case, the weight ratio of each material is chromium oxide powder 35±3
Good results can be obtained if the resin is 35±5% and the remaining amount is toluene.

When applying this ink, which is made in a concentrated liquid form, to the electrodes, it can be applied in a thin film form by brushing, spraying, or dipping methods, making it suitable for metal vapor deposition. Compared to other methods, the range of objects that can be coated is wider and the work is easier.

After the coating is finished, it is dried at room temperature for a certain period of time (within 1 hour), then preheated for about 1 hour (about 150°C) and baked for several hours (about 300°C).
The best effect is achieved by applying the coating to the entire surface of high-voltage electrodes such as the auxiliary anode 4 to suppress the generation of secondary electrons and ions caused by stray electrons that arrive. However, in the case of low-voltage electrodes such as focusing electrodes, stray electrons can On the contrary, it is preferable to apply the coating only to the edges and uneven surfaces, as there are many opportunities for it to occur.1 However, when coating a limited area like this, hand-applying methods such as brushing are appropriate. It is.

In addition to the above-mentioned electrodes, as shown in FIGS. 7 and 8, these membrane electrodes can be used on the inner surface of the glass cylinder of the bulb 16 instead of the conventional membrane electrodes formed with DAG, water-metal, or aluminum vapor-deposited films. By applying a coating, it has become possible to effectively prevent the generation of stray electrons.

As explained above, this invention has had a remarkable effect on improving the pressure resistance performance of tubes, especially small tubes and variable field of view image tubes.

In addition, since chromium oxide has a small secondary electron gain, ion spots and electron spots can be reduced, and the light absorption properties of chromium oxide reduce photocathode reflection, which is effective in improving contrast and background.

In addition, since chromium oxide is contained in a resin solution and applied to the electrode and baked, the adhesion and smoothing effect of the resin prevents dust from falling off, making it possible to omit bare metal treatment such as electrolytic treatment of the electrode, and it can be reused with hot water. Washing alone is sufficient;
In particular, the inner surface of the tube does not need to be rebaked when it is reused, and many useful practical effects can be achieved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the image tube of this invention. Explanation of symbols: 1: Input fluorescent surface and photocathode, 2: Output fluorescent surface, 3: Anode, 4: Auxiliary anode, 5° 6: Focusing electrode, 7, 8; Bend point on the bulb, 9° 10; Specific point on electrode, 11, 12; Partial coating, 13, 14; Full coating, 15; X-ray incident direction, 16; Image tube.

Claims (1)

[Scope of utility model registration request] An image tube characterized in that a chromium oxide-impregnated resin coating is formed by baking on the electrodes of the image tube or on the portions of the tube wall where the potential gradient is high.