JPS6155844A - Image pickup tube - Google Patents

Abstract

PURPOSE:To correct the focus screen of an image pickup tube and improve its aberration by causing at least two electrodes to encroach upon the target and changing the electric potentials of given areas. CONSTITUTION:Extended areas (g6) of an electrode (G6') connected to a mesh electrode encroach upon the areas (b), (d), (f) and (h) of an electrode (G5) which correspond to the four corners of the effective scanning surface 1 of a target (TA). The width of the extended areas (g6) is the widest in their center and is narrowed toward their end. The electric potential of the areas (b), (d), (f) and (h) of the electrode (G5) is higher than its other area. Accordingly, the focusing of peripheral beams corresponding to the four corners (areas b, d, f and h) of the electrode (G5) is weakened and front pins are corrected, thereby achieving improved aberration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image pickup tube in which electrodes are adhered to the inner surface of a glass bulb.

[Prior art]

There are several types of focusing/deflecting imaging tubes, but all of them have aberrations due to deflection at the corners of the target's effective scanning surface. Conventionally, in order to correct this aberration, dynamic focus correction is known in which the beam focusing power is changed depending on the deflection. For example, in electromagnetic focusing and electrostatic deflection types, instead of changing the focus coil current, the deflection electrode potential is increased at the corners to reduce aberrations caused by the so-called front focus, which focuses in front of the target. .

[Problem that the invention seeks to solve]

In the case of conventional dynamic focus correction, a correction circuit that changes the focus coil current or the deflection electrode potential is required, resulting in problems of 6D, power loss, and an increase in the number of parts. Therefore, the present invention enables dynamic focus correction without the need for a correction circuit.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention is designed to change the potential of a predetermined portion with respect to rotation by assembling two or more electrodes. For example, in the case of the electrostatic focusing/electrostatic deflection type, in the case of so-called front focus, the extension part g6 of the electrode G6 is attached to the part of the electrode G5 corresponding to the part to be corrected.
This is to increase the potential of the electrode G5 portion.

[Effect]

In the above configuration, the beam focusing power changes at a predetermined portion where the potential is changed, and therefore the focus plane is corrected,
Aberrations are improved.

〔Example〕

First, an electrostatic focusing/electrostatic deflection type image pickup tube, which is the premise of the embodiment, will be explained.

FIG. 5 shows the configuration of an electrostatic focusing/electrostatic deflection type (S-S type) image pickup tube. In the same figure, K.

G1 and G2 are a cathode, a first grid electrode, and a second grid electrode, respectively, constituting an electron gun, and LA is a beam limiting aperture. Moreover, G3 r G4 and G5 are respectively 3rd. These are the fourth and fifth grid electrodes.

These electrodes 03 to G5 are formed by, for example, depositing or plating a metal such as nickel or chromium on the inner surface of a glass bulb (not shown), and then cutting it into a predetermined pattern. Electrodes 03 to G5 constitute an electrode system for focusing, and electrode G4 also serves as a deflection electrode.

Further, G6 is a mesh-like electrode, and TA is a tag.

The electrodes 03 to G5 of this image pickup tube have a pattern as shown, for example, in a developed view in FIG.

In particular, the electrode G4 has four electrode parts H+, V+ which are insulated and interlaced in order to obtain a uniform deflection electric field.

This is a so-called Aroni pattern in which H- and V- are arranged in order in the circumferential direction. Also TH+, 'rv+ IT
H- and Tv- are electrode parts H+, V+, kite and V, respectively.
- It is formed in the area of the electrode G3 with the empty two P.

The electrode parts H+ and H- are electrode parts for horizontal deflection, while the electrode parts V+ and V- are electrode parts for vertical deflection. Although not shown, the leads TH+ and T in the electrode section H0 and the former
A sawtooth voltage with a horizontal period that changes symmetrically around a predetermined voltage is applied through H-, while the electrodes V1 and V
A sawtooth voltage with a vertical period that changes symmetrically around a predetermined voltage is applied to the leads Tv+ and Tv-, respectively, to perform horizontal and vertical deflection scanning.

Further, in FIG. 6, Gt is an electrode connected to the mesh-like electrode G6, and is similarly formed on the inner surface of the glass pulp at the same time as the electrodes 03 to G5 are formed. Also, M.A.
SL is a mark for adjusting the angle with the face plate, and SL is a slit provided to prevent electrode G3 from being heated when electrodes G1 and G2 are heated from outside the tube for evacuation.

In addition, in such an S-8 type image pickup tube, in order to improve the focusing characteristics of the electron beam on the target surface, it is necessary to increase the potential of the electrode G5 and increase the potential difference with the electrode G4. be. Furthermore, since a collimation lens is formed between the electrode G5 and the mesh-like electrode G6 to correct the landing error of the electron beam, a certain amount of potential difference is required between the electrodes G5 and 06.

Considering the above points, conventionally, for example, the potential EG3 of the t-pole G3
=500■, center potential EG4 of electrode G4 = OV, peak-to-peak value of deflection voltage Vdef = 123V,
Electrode G501E position BQ5 = 500V, potential E of electrode G6
G6=1160V, Tergutsu) TA potential ETA=5
It is designed to operate at 0V.

Furthermore, in an S-8 type image pickup tube as shown in Fig. 5,
By interlacing electrode G4 and electrode G6 with each other in the region of electrode G5, it is possible to apply the same potential as in the case where electrode G5 is present in this region, and electrode G5 can be made unnecessary. .

That is, the electrodes ear G4 and G6 are formed in a pattern as shown in a developed view in FIG. In FIG. 7, parts corresponding to those in FIG. 6 are designated by the same reference numerals.

In FIG. 7, g4 is a comb-like extension from the electrode G4, g6 is a comb-like extension from the electrode G'6, and these extensions g4 and ge are the electrodes. They are intertwined with each other in the region PG5 where G5 is to be formed. These extensions g4+ge are also formed by vapor-depositing or plating metal such as nickel or chromium on the inner surface of the glass bulb and then cutting it into a predetermined pattern in the same manner as the electrodes G3+G4*G6.

Here, if the width of the extension g4 of the electrode G4 is W4, and the width of the extension g6 of the electrode G6 is W6, then these widths W4. W6 is formed so as to satisfy the following equation.

EG5 = Shame 4 x - Knee + EG6X - 21 - W4 + W
6 W4 + W6・・・・・・・・・
・・・・・・・・・・・・(1) In this formula (1), E
G4 is the center potential of electrode G4, EG6 is the potential of electrode G6,
EG5 is the potential to be applied to region 2G5.

According to the example in FIG. 7 in which each electrode is formed, it is clear from equation (1) that even if electrode G5 is not formed,
A potential similar to that in the case where the electrode G5 is present can be applied to the region ff (, 5) where the electrode G5 is to be formed.

Next, an embodiment of the present invention will be described with reference to FIG. In FIG. 1, parts corresponding to those in FIG. 6 are designated by the same reference numerals.

In the case of an image pickup tube, the focus planes are different for the center beam and peripheral beams, and in particular, the peripheral beams are mostly focused on the front, which accounts for a large portion of aberrations. Particularly large aberrations occur at the four corners of the effective scanning surface (1) of TARDAT TA, as shown in FIG. Second
In the figure, (2) is a glass bulb.

In the example shown in FIG. 1, a plurality of extensions g6 of the electrode G6 are arranged to intertwine with the portions d, f, and h of the t-pole G5 corresponding to the four corners mentioned above. In this case, the plurality of cicada long portions g6 are widest at the center, for example, and narrow toward the ends. Although FIG. 1 only shows a portion corresponding to one of the four corners, portions d, f, and h corresponding to the other three corners are formed in the same manner.

The rest of the structure is the same as the example shown in FIG.

The electrode pattern of one embodiment is formed as described above, with portions of the electrode G5 corresponding to the four corners.

Since a plurality of extensions g6 of the electrode G6 are inserted into the portions d, f', and h, the portions d, f', and h of the electrode G5.

The potentials of f and h are higher than that of mawashi.

Therefore, the focusing power of the peripheral beam corresponding to the four corners of the electrode G5 is weakened,
Front focus is corrected and aberrations are improved.

Next, another embodiment of the present invention will be described with reference to FIG. In FIG. 3, parts corresponding to those in FIG. 7 are designated by the same reference numerals.

In the example shown in FIG. 3, the front focus at the left and right positions is corrected as shown in FIG. 4. In the example shown in FIG. 3, the widths of the extension g4 from the electrode G4 and the extension g6 from the electrode aA are changed from part to part. That is, the extension part g6 is the part j corresponding to the above-mentioned left and right positions.
, 2 and narrowed in the other part i.

The extension g4 is the opposite of this.

The rest of the structure is the same as the example shown in FIG.

The electrodes/guterns of other embodiments are formed as described above,
Since the width of the extension g6 is made wider in the portions j and P of the area 2G5 corresponding to the effective scanning surface (1) and the left and right positions, the potential of these portions J and p is higher than that in the other portions.

Therefore, the focusing power of the peripheral beam corresponding to this portion j,2, that is, the left and right positions of the effective scanning surface (1), is weakened, the front focus is corrected, and aberrations are improved.

The above embodiment is an example in which the focus surface is corrected by increasing the potential of a predetermined portion compared to the rotation, but conversely, the focus surface is corrected by lowering the potential of a predetermined portion compared to the rotation. Correction can also be performed in a similar manner.

Further, although the above-described embodiments have shown s and smO image pickup tubes, the present invention can be similarly applied to other types of image pickup tubes.

〔Effect of the invention〕

' According to the present invention described above, by interweaving two or more electrodes, the potential of a predetermined portion is changed with respect to the rotation, and the beam focusing power at this predetermined portion is changed to correct the focal plane. However, since it improves aberrations,
A conventional correction circuit is not required, and power consumption and the number of parts can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a developed view showing the pattern of an electrode according to an embodiment of the present invention, FIG. 2 is a diagram for explaining the pattern, and FIG. 4 is a diagram for explaining the same, FIG. 5 is a configuration diagram of an electrostatic focusing/electrostatic deflection type image pickup tube, and FIGS. It is a developed view showing a turn. G4 and G6 are a fourth grid electrode and a mesh electrode, respectively, and g4 and g6 are extensions, respectively. Figure 1 Figure 2 Number Figure 3 Figure 5 Figure 6

Claims (1)

[Claims] In those that form electrodes on the inner surface of the glass bulb,
An image pickup tube in which the potential of a predetermined portion is changed relative to the surroundings by interweaving two or more of the above-mentioned electrodes, and the focus plane is corrected.