JPS58198819A - Cathode ray tube manufacturing method - Google Patents

Abstract

PURPOSE:To prevent spark generation between an acceleration electrode and the neck part of a tube by providing a metal ring body on the outer circumference part of the acceleration electrode so as to surround the electrode, and forming a thin high resistance film on the neck part interior in a region facing to the acceleration electrode by subjecting the ring body to high frequency heating during an exhaust process, etc. CONSTITUTION:A negative electrode 2, a G1 electrode 3 acting as a control electrode, a cup-shaped G2 electrode 4 acting as an acceleration electrode, a G3 electrode 5 acting as a focussing electrode, and a G4 electrode 6 acting as a positive electrode are sealed in the interior of the neck part 1a of a glass valve 1, and a metal ring body 7 made of Ni or stainless steel, etc., is sealed so as to surround the outer circumference part of this G2 electrode 4. This ring body 7 is high frequency-heated by a high frequency heating coil 14 during the vacuum exhaust process for valve 1, and a thin high resistance film 13 is formed through vacuum evaporation in a region facing to the G2 electrode 4 on the neck part 1a interior. Hereby, it is possible to prevent spark generation between the G2 electrode and the neck part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a cathode ray tube configured to prevent sparks from occurring between an accelerating electrode and a valve neck.

Generally, when a spark occurs inside a cathode ray tube, an excessive current flows and there is a risk of damaging the cathode and external circuit components. Therefore, the electrodes are polished 2.

The surface of the electron gun electrode is made smooth by using a vane, or by a forced sparking process in which a high voltage approximately twice that of normal operation is applied to the electrode. However, although such treatment may be a measure to mainly prevent sparks between the anode and the focusing electrode, it may prevent sparks between the accelerating electrode, to which a low voltage is applied, and the inner surface of the pulp neck, which is charged to a high potential. This is unlikely to be a measure to prevent sparks.

According to the method for manufacturing a cathode ray tube of the present invention, a metal annular body surrounding the core is provided on the outer periphery of the accelerating electrode, and the metal annular body is high-frequency heated during the exhaust process or the subsequent manufacturing process, and the evaporated product is heated. A thin high-resistance film is deposited on the inner surface of the valve neck mainly in the area facing the accelerating electrode. The high-resistance film maintains the region at a relatively low stable potential during operation of the two-cathode ray tube, thereby preventing the generation of sparks between the accelerating electrode and the valve neck.Next, the manufacturing method of the present invention will be described in detail together with embodiments shown in the drawings.

In FIG. 1, a cathode 2. Cup-shaped G1 electrode as control electrode3. Cup-shaped G2 electrode as an accelerating electrode4. In addition to the cup-shaped G3 electrode 6 as a focusing electrode and the 04 electrode 6 as an anode, the G2 electrode 4
A metal annular body 7 made of nickel or stainless steel or the like surrounding the outer periphery of is enclosed. The cathode 2 is insulated and supported within the G1 electrode 3 by an annular insulating support (not shown), and together with the cathode 2, the G1 electrode 3°G2 electrode 4 constitutes an electron gun. The G6 electrode 5 and the G4 electrode 6 are integrally insulated and supported by electrode supporting metal pins 8 protruding from their respective outer peripheral surfaces and a plurality of glass rod-shaped insulators 9.

Further, the metal annular body 7 has an outer diameter larger than the maximum outer diameter of the G2 electrode 4 made of stainless steel, iron-nickel alloy, Kovar, etc., and is attached to the G2 electrode supporting metal pin 9. Furthermore, cathode 2. The G1 electrode 3° G2 electrode 4 and the G3 electrode 5 are each connected to a number of conductive pins 10 that hermetically penetrate the stem portion 1b of the bulb 1.
The G4 electrode 6 is in contact with a conductive film 12 made of graphite via a conductive tongue 11.

Furthermore, the conductive film 12 starts from the inner surface of the neck portion 1a of the pulp 1 in the area facing the G4 electrode 6 and spreads to the inner surface of the funnel portion 1C of the pulp 1, and is provided on the funnel portion 1C. It is in contact with the anode button (not shown).

Among the inner surfaces of the pulp neck portion 1a, mainly the G2 electrode 4
The thin high-resistance film 13 previously installed in the area facing the
It was obtained by evaporating at least the surface portion of the metal annular body 7 in vacuum.

That is, after inserting the electron gun into the pulp neck portion a, the stem portion 1b is sealed to the neck portion 1a, and the metal annular body 7 is evacuated during or after the evacuation step to evacuate the pulp 1. High-frequency heating is performed for 30 seconds to 2 minutes to evaporate a portion of the high-resistance film 13. 1
4 indicates a high frequency heating coil.

In this case, the high resistance film 13 is thickest in the region facing the G2 electrode 4, and becomes thinner as it gets further away from the region, and in the region, the thickness is such that a slight color can be seen with the naked eye. It has a certain quality.

Considering the potential distribution on the inner surface of the pulp neck portion 1a in a conventional cathode ray tube that does not have a high resistance film 13, as shown by curve a in FIG. The potential is low near . The potential distribution in the intermediate region changes depending on the surface resistance of the inner surface of the pulp neck portion 1a. That is, when the inner surface of the valve neck near the conductive film 12 becomes dirty and its surface resistance decreases, the potential in the intermediate region increases.

Further, when the temperature of the bulb neck portion 11L made of glass rises due to heat generated by the cathode 2 and the deflection yoke, the surface resistance decreases, and the potential distribution in the intermediate region becomes quite unstable. And 0 as an accelerating electrode
When the inner surface area of the pulp neck portion facing the 02 electrode 4 is charged to a high potential, sparks are likely to occur between the area and the 02 electrode 4.

By the way, when the high-resistance film 13 is attached to the inner surface of the valve neck portion 1a as described above, this high-resistance film is located between the stem-side low potential region and the conductive film-side high potential region on the inner surface of the pulp neck portion 1a. It plays the role of a leader resistance, and the film thickness in the region facing the G2 electrode 4 is large and the resistance value is small compared to the other regions, so the potential distribution on the inner surface of the valve neck is as shown in the curve shown in Figure 2. Monotona υ, G2
The potential in the region facing the electrode 4 is relatively low and stabilized, preventing sparks from occurring between it and the G2 electrode 4. Further, the surface portion of the G2 electrode 40 is hardly evaporated by high-frequency heating, and there is an advantage that the original shape of the electrode can be maintained.

The electron gun shown in Figure 1 is of the pi potential type.
Moreover, although this is a single beam type cathode ray tube, the present invention can of course be applied to a cathode ray tube equipped with a unipotential type or multiple beam type electron gun.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the main parts of a cathode ray tube embodying the present invention;
The figure shows the potential distribution on the inner surface of the pulp neck portion of the same cathode ray tube and the conventional cathode ray tube. 1...Glass pulp, 1a...Neck part of the same pulp, 4...02 electrode, 7...
・Metal annular body, 13...High resistance film. Name of agent Patent attorney Toshio Nakao and one other person □ Figure 1 Figure 2 Tenryu □

Claims (1)

[Claims] Manufacture of a cathode ray tube with a built-in electron gun, a conductive film maintained at an anode potential at one end, and a high-resistance film attached to the inner surface of the valve neck part, which has a stem part at the other end. In this step, a metal annular body surrounding the core is provided on the outer periphery of the accelerating electrode of the electron gun, and the metal annular body is high-frequency heated during the exhaust process or the subsequent manufacturing process, and the evaporated matter is heated to the high frequency. A method for manufacturing a cathode ray tube, characterized by forming a resistive film by vapor deposition.