JPS62128417A - Cathode-ray tube - Google Patents

Abstract

PURPOSE:To reduce scattering area of vapor deposition on the neck part without vapor-depositing molybdnum thereon, by forming an annular conductive lead out of a wire material whose core is made of molybdenum and surface is coated with a metal having a vapor pressure higher enough than that of molybdenum. CONSTITUTION:An annular conductive lead 15 is formed on the core made of molybdenum wire out of a wire material coated with a metal having a vapor pressure higher enough than that of molybdenum. Therefore, in a cathode-ray tube provided with such annular conductive lead 15, a vapor-deposited film 17 is formed upon exhaust process without having cupper which is evaporated by the heat of an electrode generated from a high frequency coil 16b. Further, as the evaporation starting temperature is 2,450 deg.C about 1,200 deg.C higher than that of cupper, 1,250 deg.C, if scattering of the heating temperature becomes larger due to scattering of the position of the high frequency coil 16b, the vapor- deposited film 17 can be formed by only cupper 19 coated on a core 18 without evaporating the core 18.

Description

[Detailed description of the invention] [Industrial use! f] The present invention relates to a cathode ray tube with #4 voltage characteristics.

[Prior Art] Figure 2 is a diagram showing an electron gun with the neck part of a cathode ray tube cut away. ( ) is the neck part, (2) is the stem, (3) is the electron gun, ), 1st. 2nd ° 3rd grid electrode (
5), (8), (7) and an anode (8) are each held at a predetermined interval by a bead glass (3) and constitute the main part of the electron gun (3). Further, a cup (lO) is welded to the anode (8), and this cup (10) is connected to the internal conductive film (12) via a spacer (11). (+3)
, (14) are the second . Third grid electrode (8
), (7) are connected to the inner leads.

During operation, the cathode ray system equipped with the electron gun (3) configured in this way has about 25 Kv applied to the anode (8), and the third
The voltage of the grid' electrode (7) is about 4.5 KV, the second grid electrode (8) has a voltage of about 600 V, the first grid electrode (5) has a ground voltage, and the cathode (4) has a voltage of 100 V. are applied respectively.

In such an operating state, stray electrons emitted from the cathode (4) due to scattering of beam electrons, etc.
) is accelerated by the electric field of the neck part (1) and collides with the inner wall of the neck part (1) to form a positively charged part. From the opposing part, move near the cathode (4) and move the negative J4i (4
) and the low-voltage electrode of the first grid electrode (5), causing a creeping discharge to occur, causing a phenomenon in which the conductor components constituting the cathode ray drive circuit are destroyed.

In order to prevent the occurrence of such creeping discharge, in conventional l12 electrode Ti tubes, both ends are welded to the third grid electrode (7) and a bead glass (9) is welded to the third grid electrode (7), as shown in Figures 2 to 4.
A ring-shaped conductive lead (15
), and during the manufacturing process of cathode ray tubes, a high-frequency heating coil (LEA) is heated at a position indicated by the dashed line, and an annular wire made of stainless steel wire coated with copper is heated. Heat and evaporate the adhesive layer (15) on the lead '1 and deposit +1 on the inner wall surface of the opposing untied part (1).
! 2(17) to form 1,1t)-, It! , so that the movement of the parts is inhibited by this deposition n*, (+7).

[Problems to be solved by the invention] When a stainless steel wire core wire coated with copper is used as the annular conductive lead (15), the metal forming the Ml of the stainless steel wire is in the neck portion ( The temperature for vapor deposition on the inner surface of 1) is 14 (10°C), while the group n temperature for copper is 1250°C, a difference of about 150°C.However, the position of the heating coil during the evacuation process If the heating temperature of the annular conductive lead (15) exceeds 150°C due to variations in the heating temperature, not only copper but also the components that make up the stainless steel wire will begin to evaporate, causing the inner surface of the neck part (1) to evaporate. The area of the evaporation surface (17) on which the evaporation is performed becomes large, and there is a problem that damage to the electrodes and neck glass occurs during high-voltage treatment.

This invention was made with the aim of solving these problems, and even if the heating temperature varies widely, the evaporation surface (
17) The objective of El is to obtain a cathode ray tube with small variations in size.

[Means for Solving the Problems] This invention is characterized in that an annular conductive lead is formed on a core wire of a molybdenum wire by a wire coated with a metal having a sufficiently higher vapor pressure than molybdenum. do.

[Function] The vapor pressure of molybdenum constituting the core wire of the annular conductive lead is sufficiently lower than the vapor pressure of the Ya metal. Therefore, due to variations in the position of the heating coil during the exhaust process, Even if the heating temperature of the annular conductive lead rises to a temperature considerably higher than the deposition temperature of the coating metal, it does not reach the temperature at which molybdenum is deposited, so that only the coating metal is deposited on the inner surface of the neck. Therefore, even if the height t of the heating coil varies, it is possible to form 78 contact surfaces with little variation in width.

[Embodiment] Fig. 1 is a partially enlarged cross-sectional view of an electron gun for explaining the essential parts of this invention, and shows the part corresponding to Fig. 54.

In the figure, (15) is an annular conductive lead with a copper coating, and a core wire (18) made of molybdenum wire.
Copper coating (1!9) covering the surface of the core wire (18)
The attachment position and shape of the third grid electrode (7) are the same as those of the conventional annular conductive lead (15).

In a cathode ray tube equipped with such an annular four-electrode lead (15), during the exhaust process, copper is evaporated by the heating of the electrode by the high frequency coil (18b) shown in Fig. 2, forming a deposited film (17). can be formed.

In addition, the evaporation temperature fJN of molybdenum is 2450°C, which is about 1200°C compared to the evaporation temperature of copper which is 1250°C.
℃, so even if the heating temperature varies widely due to variations in the position of the high frequency coil (+8b), the core wire (1
8) without evaporating the core wire (18).
The deposited film (17) can be formed using only the copper (19) present.

Additionally, the area where the vapor deposited film (17) is formed expands, and as shown in FIG. 3, the area near the third grid electrode (7) (
20) Once inside, the anode (8) and the third grid electrode (7) are exposed to intense heat through the vapor deposition 1!2 (17) during the high voltage treatment applied in the manufacturing process of cathode ray tubes. Discharge occurs, causing cracks in the neck part (1), or the anode 8i (8) becomes so hot that the metal that makes up the anode (8) evaporates and forms a deposited film, causing a rough and intense discharge. This creates a vicious cycle that can lead to damage to the cathode ray tube. Therefore, there are planets that limit the area on which the deposited film (17) is formed, but the thickness of the copper coating (19) should be set between 0.05 and 0.05 mm.
By configuring the thickness in the range of 3 μm, a deposited film (17) with an appropriate spread can be formed, and the discharge between the anode (8) and the third grid electrode (7) as described above can be prevented. This can be prevented from occurring.

In the above embodiment, the case where the core wire (18) is coated with 1 g of copper metal layer (18) is explained, but this metal layer (19) is coated with a copper metal layer (19) of The material is not limited to copper as long as it is made of a metal with a high temperature rt.

[Effects of the invention] This invention uses a molybdenum wire as a core wire for the annular conductive lead that is melt-welded to the third grid electrode and surrounds the bead glass, and uses a metal whose vapor pressure is sufficiently higher than that of molybdenum. Since the wire rod is coated with metal, even if the position of the high-frequency heating coil varies during the exhaust process and the heating temperature significantly exceeds the kri temperature of the coated metal, it will not reach the molybdenum deposition temperature. Since the molybdenum does not reach the target region, molybdenum is not deposited, and variations in the deposition area at the neck portion are reduced.

[Brief explanation of drawings]

FIG. 1 is a partially enlarged cross-sectional view of an electron gun showing the configuration of the main parts of an embodiment of this invention, FIG. 2 is a diagram showing the configuration of the electron gun with the neck section of a cathode ray tube cut away, The figures are a cross-sectional view taken along line 2--m in FIG. 2, and FIG. 4 is a cross-sectional view taken along line TV--TV in FIG. 3, showing the structure of a conventional electron gun corresponding to FIG. 1. (1) Neck, (3) Electron gun, (7)
...Grid electrode, (8)...Bead glass, (15)
...Annular conductive lead, (17)...Vapor deposition surface, (1
8) Core wire, (19) Metal layer. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (3)

[Claims] (1) A bead glass is fixed to the grid electrode of the electron gun housed in the neck part, surrounds the outer surface of the bead glass holding each electrode of the electron gun, and is interposed between the inner wall surface of the neck part. The ring-shaped conductive lead is heated and evaporated by a high-frequency heating device installed at a predetermined distance, and the ring-shaped conductive lead is placed opposite to the ring-shaped conductive lead. In a cathode ray tube configured such that a vapor-deposited film is formed on the inner wall surface of the neck portion, the annular conductive lead is made of a metal whose vapor pressure is sufficiently higher than that of molybdenum, and whose core wire is a molybdenum wire. A cathode ray tube characterized in that it is formed from a wire coated with. (2) The cathode ray tube according to claim 1, wherein the coating metal layer of the conductive lead is copper. (3) The thickness of the coating metal layer of the conductive lead is 0.05 to 0.
．． The cathode ray tube according to claim 2, which has a diameter of 3 μm.