JPS5929326A - Television camera tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a television image tube equipped with electrodes, deflection coils and focusing devices. Television image pickup tubes of this type are also used, inter alia, in X-ray diagnostic equipment equipped with a television device.

The television image pickup tube and vidicon in this building are described on pages 75 and 76 of the book IX@Television 6 written by A, Gθbau, er, and others.

The cooperative action of the four electrodes produces a narrowly focused electron beam originating from the cathode, and this quantum beam is directed by a focusing coil to the target of the television tube.
It occurs because it is focused on two things. The deflection of the electron beam (for partial scanning of the target) is effected by a deflection coil.

Direct current is passed through the focusing coil, which generates heat. To increase the resolution, an increased electrode voltage of the television I# tube is used, so the focused energy needs to be increased by the root of the voltage rise rate. In particular, this heat increases the dark current in the case of vidicons with an antimony trisulfide layer, increases the number of spots and spot contrast in the case of cadmium selenide tubes, and irreversibly damages the target layer in the case of selenium arsenide layers. This may cause severe damage.

In order to reduce this heat, a television image pickup tube that performs electrostatic focusing has already been proposed. However, the drawback of this type of image pickup tube is that its resolution characteristics are poor. It is mentioned as.

SUMMARY OF THE INVENTION An object of the present invention is to provide a television image pickup tube equipped with a magnetic focusing device that generates less heat while maintaining good resolution.

This object is achieved according to the invention by providing the focusing device with at least one permanent magnet which is ring-shaped and magnetized in the axial direction.
This is accomplished by having the permanent magnet coaxially surround the deflection tube and the television imager tube. This permanent magnet can eliminate at least a portion of the ttt power that is converted into heat in the television image pickup tube.

By providing an intermediate layer between the permanent magnets, a magnetic field can be created in a desired manner. If the intervening spaces between the permanent magnets or intermediate layers are filled with spacers, the focusing device can be constrained with a better Q. Preferably, this spacer or part of it has a higher magnetic permeability than air.

Guidance of the focusing device near the target is enhanced by making the spacing of the permanent magnets near the target of the television imager tube smaller than the opposite (till) of the target. By inserting a strip of ferromagnetic material between the two, the symmetry and strength of the magnetic field can be adjusted.

The focusing effect can be suitably adjusted by the measures described in the other fτj band requirements.

The invention will be explained in more detail by means of illustrated embodiments.

A television image tube 1 of the vidicon type is shown in the figure, surrounded coaxially by a deflection coil 2 and a focusing device 3. FIG. A target 5 made of a signal board equipped with an optical semiconductor is provided on one side of the glass bulb 4 of the television imaging W1. There is a connection plug 6 on the opposite side of the glass bulb 40.
stands out.

On this side, a cathode 7 surrounded by a Wehnelt cylinder 8 is provided. In front of it is an anode 9. Electrode J
Another electrode consisting of O and a reticular electrode 11 is provided.

Eleventh, the focusing device 3 comprises a ring-shaped permanent magnet 12 magnetized in the axial direction, the intervening space between which is filled with a spacer 13 . target 5
Near zero, the permanent magnets 12 have a smaller spacing than on the side of the connecting plug 6.

The inner and outer surfaces of the focusing device 3 are provided with strips 14 made of ferromagnetic material, for example sheet metal strips.

The outer strip 1/l interconnects three permanent magnets 12, and the inner strip 14 interconnects two permanent magnets 12.

Furthermore, these bands can be as large as the entire length and/or circumference V of the focusing device 3. These bands 14 act as magnetic current shunts and reduce the induction inside the permanent magnet. In this way, if the permanent magnet 12 is non-uniform, the induction is straightened and the desired In size,
Thieves can be a little.

In FIG. 2, another embodiment of the focusing device 3 is shown,
In this case, a ferromagnetic intermediate layer 35 is provided between the permanent magnets 12 . Further, in this case, the intervening space is filled with the spacer J3. In order to finely adjust the focusing effect, a focusing coil 16, which is made smaller than a normal focusing coil, is provided between the deflection coil 2 and the permanent magnet 12.

The adjustment can also be carried out by movably providing one or several permanent magnets 12 inside the focusing device 3. Since the focusing action of the focusing device 3 and the strength of the magnetic field depend on the voltages of the anode 9 and the reticulated pole 11, adjustment can also be carried out by changing these voltages; Adjustment can be made without the need for additional focusing coils 16.

The resolution of television imaging +g 1 is improved by increasing the guidance near the target through a dense arrangement of permanent magnets.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing one embodiment of the invention, and FIG. 2 is a side sectional view showing another embodiment of the invention.・Television m(a'tL 2...Deflection coil, I, 3...Focusing device, 4...Glass bulb, Death...Target, 6...Connection plug, 7...Cathode, 8...・Wehnelt cylinder, 9...anode, 10...electrode, 11...
・Mesh electrode, 12...Permanent magnet, 13...Spacer, 1
4. Obi, J5...middle b ■, 16. Focusing carp I. 111

Claims (1)

[Claims] 1) The focusing device (3) has at least one ring-shaped permanent magnet (12) magnetized in the axial direction, which permanent magnet (12) is connected to the deflection coil (2) and the television set. A television image pickup tube (1) equipped with electrodes, a deflection coil and a focusing device, characterized in that the television image pickup tube (1) is coaxially enclosed. 2) The television tube according to claim 1, characterized in that a ferromagnetic intermediate layer (15) is disposed between the permanent magnets (12). 3) The television image pickup tube according to claim 11 or claim 2, characterized in that the intervening space between the permanent magnet (12) and the intermediate layer (15) is filled with a spacer (13). 4) The television expansion tube according to claim No. 31, characterized in that the spacer (13) has a higher magnetic permeability than air. 5) The distance between the permanent magnets (12) near the target (5) of the television image pickup tube (1) is smaller than that on the opposite side of the target (5). The television image pickup tube according to any one of No. 4@. 6) A band made of ferromagnetic material (
14) The television image pickup tube according to any one of claims 1 to 5, characterized in that the television image pickup tube is provided with: 7) At least one permanent magnet (1
2) The television image pickup tube according to any one of claims 1 to 6, wherein the television image pickup tube is provided in a movable manner. 8) According to any one of claims 1 to 7, the voltage of at least one electrode (9 to 11) of the television image pickup tube is made variable in order to adjust the degree of focusing. television image tube. 9) The television image pickup tube according to any one of claims 1 to 8, characterized in that the focusing device (3) for adjusting the focusing degree is additionally provided with a focusing coil (J6). .