JPS6199247A - Heater structure for chip-off of exhaust tube for electron tube - Google Patents

Abstract

PURPOSE:To make the exhaust tube after the seailng shorter than a stem pin by forming a heater structure for chip-off of exhaust tube for electron gun with a heat conductor, a heater and a heat shielding material which shields the heat at the part other than the cutting portion of exhaust tube. CONSTITUTION:At the lower part of aperture of heat resistive socket 1, a heat conductor 5 consisting of metal such as nichrome having a small diameter part 5a and a large diameter part 5b, a heater 2 wound around said large diameter pat 5b and a heat shielding material 8 such as ceramic material to be inserted to the internal side of said large diameter part 5b are arranged. An electron tube 3 having an exhaust tube 3a and a stem pin 3b is loaded to a socket 1, the small diameter part 5a of heat conductor 5 is located between the exhaust tube 3a and stem pin 3b. After the exhaustion, the heater 2 is heated and cut and sealed at the position 4 of exhaust tube 3a. Therefore, the length of exhauste tube 3a after the sealing can be set shorter than the stem pin 3b and total length of electron tube can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a heater structure for tip-off of an exhaust pipe for an electron tube, which is suitable for sealing the exhaust pipe of an electron tube.

[Background of the invention]

In recent years, in order to reduce the size of VTR camera bodies that use, for example, image pickup tubes as electron tubes, the exhaust pipe of the image pickup tube, which is completely unnecessary during use, has been made as short as possible. This leads to miniaturization and is one of the important points.

Conventionally, in electron tubes, a so-called tip-off process has been carried out, in which the exhaust pipe for degassing inside the tube is sealed by melting it with a heat source such as a burner or an electric heater after the evacuation is completed. (Refer to Publication No.-6754).

FIG. 1 is a diagram for explaining an example of tipping off an electron tube exhaust pipe using an electric heater as a heat source. That is, as shown in the same figure, a heater 2 for removing a small tube is arranged under the opening of a heat-resistant socket 1 having an opening of a predetermined size.
By attaching the stem sealing upper part of the electron tube 3 having an exhaust pipe 3a and a plurality of stem pins 3b to this opening, and heating the heater 2 after the exhaust pipe 3a completes exhaust gas, the exhaust pipe 3a can be closed. Melt the stem pin 3
It is sealed by melting and cutting at the cutting position 4 of the tip portion of b.

However, according to such a sealing method, the exhaust pipe 3
Due to the positional relationship of the heater 2, the sealing part a is always sealed and cut at a further point than the tip of the stem pin 3a, so the length of the exhaust pipe 3a after sealing is equal to the length of the stem pin
longer than the length of b, therefore! The overall length of the daughter tube 3 also increased, which became an obstacle to downsizing the VTR camera body.

On the other hand, to reduce the size of VTR camera bodies, there has been an active competition to make tubes smaller in recent years, and many new products have been developed, requiring the overall length of the electron tube to be shortened by even 1 mm. ), even under such circumstances, the tip-off length of the exhaust pipe is hardly shortened for the reasons mentioned above.

[Purpose of the invention]

Therefore, the present invention was developed in view of the above-mentioned problems, and its purpose is to perform the prong-off of the exhaust pipe inside the stem pin, and to adjust the length of the exhaust pipe after sealing to the stem pin. It is an object of the present invention to provide a heater structure for tip-off of an exhaust pipe for an electron tube, which can shorten the length of the exhaust pipe.

[Summary of the Invention] In order to achieve the above object, the tip-off heater structure of an exhaust pipe for an electron tube according to the present invention includes a heat conductor that conducts thermal energy to a cut portion of the exhaust pipe, and this heat conductor. It consists of a heater that heats the exhaust pipe, and a heat insulator that insulates the parts of the exhaust pipe other than the cut part.

[Embodiments of the invention]

Next, embodiments of the present invention will be described in detail using the drawings.

FIG. 2 is a sectional view of a main part showing an embodiment of a tip-off heater structure for an electron tube exhaust pipe according to the present invention, and the same parts as in FIG. 1 are given the same reference numerals. In the figure, reference numeral 5 denotes a nearly funnel-shaped heat conductor having a small diameter part 5a and a large diameter part 5b formed of a highly heat-resistant metal such as nichrome, stainless steel, or beryllia. The small diameter portion 5a of the heat conductor 5 has an inner diameter slightly larger than the outer diameter of the exhaust pipe 3a, and has an outer diameter slightly smaller than the inner diameter of the circular arrangement of the stem pins 3b.
) is formed to have a length in the tube axis direction that can be inserted up to the stem sealing portion of the tube. On the other hand, a heater 2 for heating the heat conductor 5 to a predetermined temperature is wound around the outer surface of the large diameter portion 5b of the heat conductor 5, and an exhaust pipe 3a is freely disposed inside the heater 2. It is formed with a through hole large enough to allow insertion and extraction.

Further, a cylindrical heat insulator 6 made of, for example, a ceramic material is inserted and arranged inside the large diameter portion 5b of the heat conductor 5.

In such a configuration, by attaching the stem sealing part of the electron tube 3, which is provided with the exhaust pipe 3a and the stem pin 3b, to the opening of the socket 1, the small-diameter part 5a1ll of the heat conductor 5 is connected to the femoral bone 3. Since the exhaust pipe 3a and the stem pin 3b are inserted up to the root part,
By heating the heater 2 after the exhaust is completed, the thermal energy is conducted through the large diameter portion 5b of the heat conductor 5, heats and raises the temperature of the root portion of the exhaust pipe 3a via the small diameter portion 5a, and melts the stem pin. It can be melt-cut and sealed at the cutting position 4 inside 3b. Note that the heat conductor 5 and the exhaust pipe 3a disposed within the large-diameter portion 5b are insulated by the heat insulator 6, so that they will not be melted. In this case, in order to prevent contact with the stem pin 3b, the thickness of the socket 1 is made thinner to prevent contact with the stem pin 3b, and the electrical connection of the stem pin 3b is made using the outer peripheral surface of the stem pin 3b, and the overall temperature is compared. Maintain the temperature at a high temperature of 200 to 300℃, paying attention to improving the temperature distribution and preventing glass distortion in the upper part of the stem seal.
Conditions need to be set.

Further, as a result of tipping off an image pickup tube having a total length of 1/3 inch using the tip-off heater structure configured as described above, the total length could be shortened by about 5%.

〔Effect of the invention〕

As explained above, according to the present invention, the exhaust pipe of the electron tube can be tipped off inside the stem pin.
An extremely excellent effect can be obtained in that the total length of the electron tube can be shortened and the electron tube device can be downsized.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part explaining an example of a conventional electron tube exhaust pipe tip-off method, and FIG. 2 is a cross-sectional view showing an example of a heater structure for tip-off of an electron tube exhaust pipe according to the present invention. 1st life... O socket, 2nd @ heating heater, 3rd...
・Electron tube, 3B@Ki... Exhaust pipe, 3a'... 1. Exhaust pipe after sealing, 3b@Φ stem pin, 4-... Cutting position, 5... Φ thermal conductor, 5a. ...Small diameter part, 5b
・・・・Large diameter part, 6・Fig. 1

Claims (1)

[Claims] An exhaust pipe for an electron tube that includes a thermal conductor that conducts thermal energy to a cut part of the exhaust pipe for an electron tube, a heater that heats the heat conductor, and a heat insulator that insulates a part of the exhaust pipe other than the cut part. Heater structure for chip-off.