JPS5838907B2 - Electrostatic focusing picture tube and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic focusing picture tube equipped with a vent gun and a method for manufacturing the same.

Bent guns, which have a partially bent focusing electrode, were developed to prevent ion burning of the phosphor film, but with the advent of metal-back phosphor surfaces, they were no longer used in general television picture tubes. Ta.

On the other hand, picture tubes that take out the television playback image from the inner surface of the phosphor film (on the electron gun side), such as the projection tubes of Schott-type projection television receivers, are metal-backed, could not be adopted, and attempts were made to use a vent gun.

However, in a picture tube using a vent gun, not only is it complicated to adjust the ion trap magnet, but also leakage magnetic flux from the magnet can easily penetrate into the electron lens, causing unwanted deflection of the electron beam. There is a problem.

For this reason, commercially available projection tubes use an electromagnetic focusing method that narrows down the ions relatively little to prevent ion burning of the phosphor film, but in this case, an expensive focusing magnet is required. It also has drawbacks such as a long picture tube.

The present invention has been made with the above-mentioned points in mind,
DESCRIPTION OF THE PREFERRED EMBODIMENTS The picture tube and method of manufacturing the same according to the present invention will be explained in detail below with reference to embodiments shown in the drawings.

Referring to FIG. 1, which shows an embodiment in which the present invention is applied to a projection tube, an electron gun 3 enclosed in a neck portion 2 of a glass bulb 1 includes a cathode 4, a control grid electrode 5, an accelerating electrode 6, a bent A focusing electrode 7 and an anode 8 are provided, and at least the focusing electrode 7 is made of a non-magnetic metal.

Further, the target electrode 10 sealed in the funnel part 9 of the glass bulb 1 has a phosphor film 11 on its spherical convex surface, and has an appropriate number of metal electrode support pieces extending from the target electrode 10. The outer edge of the metal tube 12 is fixed to one opening edge of the metal tube 13, and the reflecting mirror 14 fixed to the other opening edge of the metal tube 13 has a spherical concave light reflecting surface 15 and a central hole 16. have.

Then, an appropriate number of metal spring pieces 18 protruding from the outer peripheral surface of the metal cylinder 13 engage with an appropriate number of metal pins 17 whose bases are embedded in the funnel portion 9, and the anode 8 and the target electrode 10 are electrically connected via the conductive tongue piece 19, the internal conductive film 20, the pin 17, the spring piece 18, the metal tube 13 button, and the electrode support piece 12.

Furthermore, a ring-shaped magnetic body 21 is provided in the neck part 2 and surrounds the bent part 7' of the focusing electrode 7, and the central axis A of the ring-shaped magnetic body 21 extends between the cathode 4 and the control grid electrode 5. It is located between the axis B of the triode consisting of the accelerating electrode 6 and the tube axis C.

In addition, the magnetic shield plates 22 and 23 provided opposite to the surface of the ring-shaped magnetic body 2102 are made of pure iron or the like, and the leakage magnetic flux of the magnetized ring-shaped magnetic body 21 penetrates into the main lens and the brifocus lens side. prevent

In addition, as the ring-shaped magnetic body 21, Vicallo
y (36 to 62 weight percent co, 6 to 16 weight % V, balance Fe) or ferrite can be used.

At the time when the ring-shaped magnetic body 21 is sealed in the neck portion 2, it is not yet magnetized, and the magnetization process is performed when the picture tube is almost completed.

In other words, the picture tube is operated by applying a voltage that matches the typical operating conditions of the picture tube to each electrode of the picture tube, which has been almost completed through various processes such as sealing, exhaust button, aging, etc. At this time, a pulse signal suitable for measuring the electron beam spot is used as the video signal, and no signal is given to the deflection yoke.

Therefore, the electron beam emitted from the cathode 4 and passing through the control grid electrode 5 and the accelerating electrode 6 travels straight along the axis B of the triode and does not reach the target electrode 10.

Therefore, as shown in FIG. 2, magnetizing devices 24 and 2 are provided outside the neck portion 2 to sandwich the ring-shaped magnetic body 21 from the left and right sides.
An excitation current is passed through 5 to magnetize the ring-shaped magnetic body 21.

Then, the electron beam is directed toward the tube axis C side, and while monitoring the position and shape of the beam spot that appears on the phosphor film 11 with the naked eye or with an appropriate sensor, it is possible to determine the best position and shape of the beam spot. Ring-shaped magnetic body 2
1 is gradually magnetized.

At this time, it goes without saying that the positions of the magnetizing devices 24 and 25 may be appropriately moved and the magnitude of the excitation current supplied to the devices may be adjusted.

The direction of the electron beam must be controlled only by the magnetic field of the ring-shaped magnetic body 21, but the direction of the electron beam must be controlled only by the magnetic field produced by the ring-shaped magnetic body 21.
If you are accustomed to being affected by the excitation magnetic field of 25,
It is possible to intermittent the excitation current, or to use a correlation table that graphs the relationship between both magnetic fields.

Furthermore, a plurality of ring-shaped magnetic bodies 21 may be provided.

The television reproduction image obtained on the phosphor film 11 is reflected by the light reflecting surface 15 of the concave mirror 14 and then projected onto a projection screen (not shown).

A plurality of small pieces of magnetic material may be used in place of the ring-shaped magnetic material 21, and this embodiment is shown in FIGS. 3 and 4.

In other words, the two small pieces of magnetic material indicated by numbers 26 and 27 in the figure form a permanent magnet for an ion trap, and the number 2
Two piece-like magnetic bodies indicated by 8 and 29 form permanent magnets for correcting the trajectory of the electron beam.

However, if the assembly accuracy of the electron gun is sufficiently high, the magnetic bodies 28 and 29 are not required.

As described above, according to the present invention, since the ion trap magnetic material (magnet) is provided between the bent part of the focusing electrode made of non-magnetic metal and the valve neck part, the magnet can be extremely small. The leakage magnetic field of the magnet is also narrow, which greatly reduces unwanted deflection of the electron beam.

Furthermore, since the magnet does not protrude outside the tube, there is more space outside the tube.

Furthermore, since the magnetization process is carried out under the operating conditions of the picture tube, it can be adapted to the unique characteristics of the picture tube, taking into account the magnetic influence of the magnetic shield plate, etc., so that the best conditions for the storage and storage can be achieved. It has the advantage of being magnetic.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a picture tube embodying the present invention, FIG. 2 is a perspective view showing the relationship between the picture tube and a magnetizing device, and FIG. 3 is a picture tube according to another embodiment of the present invention. A side sectional view showing the part,
FIG. 4 is a sectional view taken along line A-A' in FIG. 2...Neck part, 3...Bent gun,
7... Focusing electrode, 10... Target electrode, 11... Fluorescent film, 21.26, 27,
28, 29...Magnetic material, 22.23...
・Magnetic shield plate, 24.25...Magnetizing device.

Claims (1)

[Scope of Claims] 1. A vent gun sealed in the neck of a glass bulb is provided with a focusing electrode made of a non-magnetic metal, and a magnetized ion trap for ion trapping is provided between a bent part of the focusing electrode and the neck. An electrostatic focusing picture tube characterized in that a magnetic material is provided, and the magnetic material is magnetically shielded from the electron lens portion by a magnetic shield plate enclosed within the neck portion. 2. The vent gun sealed in the neck of the glass bulb is equipped with a focusing electrode made of a non-magnetic metal, and the ion trap magnetic material provided between the bent part of the focusing electrode and the neck is magnetized, 1. A method for manufacturing an electrostatic focusing picture tube, characterized in that the manufacturing method is carried out using a magnetizing device provided outside the picture tube depending on the operating state of the picture tube.