JPH04106838A - Metal band heating apparatus for shrink-fitting-type explosion-proof cathode-ray tube - Google Patents

Abstract

PURPOSE:To carry out heating to a prescribed temperature stably by putting a magnetic material in the way of enabling the material to be inserted onto the inside of a spiral coil between a high frequency induction coil and a high frequency electric power source and adjusting the self-inductance of the high frequency induction coil corresponding to the alteration of the load of a metal band during heating. CONSTITUTION:A spiral coil 21 is put in the middle of a circular part 20 of a high frequency induction coil 16 and an electric power source connection part and a ferrite 22 is so set as to be detached freely and able to be controlled its insertion level. According to the alteration of load R of a metal band 11 during heating, the ferrite 22 is inserted into the inside of the spiral coil 21 properly by operation of an air cylinder 23 to alter the permeability and adjust the self-inductance L of the high frequency induction coil 16. As a result, independently of the shape and the inner circumferencial length of the metal band 11, the metal band 11 is heated to a prescribed temperature in a set period and stable explosion preventing treatment is carried out.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a metal band heating device for a shrink-fit type explosion-proof cathode ray tube, and particularly relates to a metal band heating device for a shrink-fit type explosion-proof cathode ray tube. This invention relates to a metal band heating device for an explosion-proof cathode ray tube.

(Prior Art) As shown in FIG. 2, a cathode ray tube such as a color picture tube has a substantially rectangular glass panel (2) with a skirt (1) formed around its periphery, and this panel (2). ) has an envelope (4) consisting of a funnel-shaped glass funnel (3) integrally joined to the panel (2), facing the shadow mask (5) attached to the inside of the envelope (4). 2)
A phosphor screen (6) consisting of a three-color phosphor layer is formed on the inner surface and emits three electron beams (9) emitted from an electron gun (8) disposed within the neck (7) of the funnel (3). Formed into a structure that displays an image by scanning the phosphor screen (6) horizontally and vertically by deflecting it by a magnetic field generated by a deflection yoke (not shown) attached to the outside of the funnel (3). has been done. Since the inside of the envelope (4) is evacuated to a high vacuum, it is distorted by atmospheric pressure and may implode if an external shock is applied to it. For this reason, explosion-proof measures have conventionally been taken to prevent implosion.

There are various methods for explosion-proofing this cathode ray tube, but the most widely used is the shrink-fitting method, in which a metal band (11) is attached to the outer periphery of the skirt portion (1) of the panel (2), which is the largest diameter portion, by shrink-fitting. This shrink-fitting method is an explosion-proof method in which the outer periphery of the skirt portion (1) of the panel (2) is tightened by the contraction of the metal band (11) expanded by heating as it cools.

Conventionally, the metal band (11) is attached using this shrink-fitting method.
As shown in FIG. 3, a protective tape (13) is wrapped around the outer periphery of the skirt portion (1) of the panel (2) of the color picture tube manufactured by a predetermined process. Skirt part (1) of shaped panel (2)
A nearly rectangular annular body (14) with an inner circumference shorter than the outer circumference
A metal band (11) is formed at the four corners of this annular body (14) to which support fittings (15) for attaching the color picture tube to the cabinet are fixed, and this metal band (11) is heated. Inflate the above skirt part (1)
Insert it so that it is positioned on the protective tape (13) wrapped around the outer periphery.

Thereafter, the metal band (11) is cooled, and as it shrinks as it cools, the skirt portion (1) of the panel (2) is tightened via the protective tape (13).

Conventionally, as a heating device for the metal band (11), as shown in FIG. ) connected to the high frequency power supply unit (17
), and as a result, the metal band (1
There is a high-frequency induction heating device that heats the entire circumference of a metal band (11) using the hysteresis loss of the high-frequency induced current that occurs in 1).

(Problem to be Solved by the Invention) In general, as the cathode ray tube becomes larger, the metal band also becomes larger and has a larger heat capacity. It is suitable as a heating device for metal bands because it can heat it in a relatively short time regardless of its size.

However, in conventional high-frequency induction heating devices, the lower the output, the lower the cost, so current-type inverters, which use metal bands as the load of a parallel resonant circuit, have become mainstream, making it impossible to obtain high oscillation frequencies. There is a problem. In other words, metal bands are usually formed by press-forming a band-like member cut to a predetermined length, and then welding both ends of the band, so there may be slight variations in the shape and dimensions such as inner circumference. There is variation. Therefore, if the oscillation frequency of the high-frequency current supplied from the high-frequency power supply section is low, the heating temperature changes depending on the shape change or dimensional error, and the heating temperature may not reach the predetermined temperature within the set time. If the metal band is not heated to a predetermined temperature in this way, the inner circumference of the metal band after heating will be smaller than the outer circumference of the maximum diameter part of the cathode ray tube, or a sufficient difference in circumference will not be obtained, and as a result, the metal band will This causes problems such as not being able to install it in the specified position, reducing the explosion-proof effect, and not being able to install it in the cabinet because the supporting metal fittings are inappropriately positioned.

The present invention has been made to solve the above problems, and the metal band of a shrink-fit type explosion-proof cathode ray tube is heated by a high-frequency heating device consisting of a current-type inverter with a parallel resonant circuit as a load. The purpose is to enable stable heating to a predetermined temperature without being affected by changes or dimensional errors such as inner circumference length.

[Configuration of the Invention (Means for Solving the Problems) The present invention includes a high-frequency power source and a high-frequency induction coil that heats a metal band with a current supplied from the high-frequency power source,
In a metal band heating device for a shrink-fit type explosion-proof cathode ray tube, which is comprised of a current-type inverter that uses a metal band heated by the high-frequency induction coil as a load of a parallel resonant circuit, a spiral coil is connected between the high-frequency power supply section and the high-frequency induction coil. A spiral coil is provided, and a magnetic member is insertably arranged inside the spiral coil, so that the self-inductance of the high-frequency induction coil can be adjusted in accordance with load fluctuations during heating of the metal band.

(Function) The resonant impedance ZO of the parallel resonant circuit and the load R when heating the metal band are 20 = L/CR, where L is the self-inductance of the high-frequency induction coil and C is the capacitance.
・・・・・・・・・・・・・・・・・・(There is a relationship of As the electric power fluctuates, it becomes impossible to stably heat the metal band. However, if the heating device is configured as described above, the amount of insertion of the magnetic member into the spiral coil will allow the metal band to be heated in a stable manner depending on the fluctuations in the load R. The self-inductance L can be adjusted by adjusting the self-inductance L, and as is clear from the above equation (1), the resonant impedance ZO
The metal band can be stably heated to a predetermined temperature by preventing fluctuations in the temperature.

(Example) Hereinafter, the present invention will be described based on an example with reference to the drawings.

FIG. 1 shows a heating device that is one embodiment of the invention.

This heating device uses the metal band (
The metal band (11) has an annular high-frequency induction coil (16) of approximately the same shape and a high-frequency power source (17) connected to the high-frequency induction coil (16), which is placed inside the metal band (11). It consists of a current type inverter as the load of a parallel resonant circuit. In this heating device, a spiral coil (21) is provided between the annular portion (20) of the high frequency induction coil (16) and the power supply connection portion, and A columnar ferrite (22) is arranged, and the ferrite (22) can be inserted into and removed from the inside of the spiral coil (21) by driving an air cylinder (23), and the amount of insertion can be adjusted. There is.

By the way, the metal band (11) of the shrink-fit type explosion-proof cathode ray tube
When the heating device for heating the metal band (11) is configured as described above, the air cylinder (23) is driven to heat the ferrite (22) in the helical coil (21) according to the fluctuation of the load R during heating of the metal band (11). The metal band (11
) The metal band (11) can be heated to a predetermined temperature in a set time without being affected by variations in dimensions such as the shape and inner circumference length, and stable explosion-proof treatment can be performed.

That is, when a metal band (11) is heated by a high-frequency induction heating device consisting of a current type inverter with a metal hand as a load of a parallel resonant circuit, the resonance impedance ZO of the parallel resonant circuit and the metal band (11) are heated as described above.
20-L/CR between the self-inductance L and capacitance C of the high-frequency induction coil (16) of the load R1 during heating.
...There is the relationship (1), and since the load R on the metal band changes greatly due to heating, the resonant impedance z
O fluctuates, and as a result, power consumption fluctuates, and the metal band (
11) The heating temperature fluctuates.

Therefore, depending on the variation ΔR of the load R, the spiral coil (
21) and adjust the self-inductance L of the high-frequency induction coil (16) (adjustment amount: ΔL), 20-(L+ΔL)/C(R+ΔR)・Old...( 2)
This prevents fluctuations in the resonant impedance ZO, and prevents fluctuations in the mounting position of the metal band and support metal fittings, which would otherwise occur due to variations in the metal band's shape, inner circumference length, etc. Problems such as inappropriate positioning can be solved, and stable explosion-proof treatment can be performed by heating to a predetermined temperature at a set time.

[Effects of the Invention] In a metal band heating device for a shrink-fit type explosion-proof cathode ray tube, which consists of a current type inverter that uses a metal band heated by a high frequency induction filter as a load of a parallel resonant circuit, the metal band of the cathode ray tube is heated by a high frequency induction coil. If a spiral coil is provided between the high frequency power source and a magnetic member is inserted into the spiral coil, the amount of insertion of the magnetic member into the spiral coil can be adjusted to reduce the load on the metal band during heating. By adjusting the self-inductance of the high-frequency induction coil according to the fluctuations, it is possible to eliminate fluctuations in the resonant impedance of the parallel resonant circuit and heat the metal band to a predetermined temperature in a set time. It is possible to solve problems such as improper positioning of the metal band and the inappropriate position of the supporting metal fittings, which occur due to the lack of the metal band, and provide stable explosion-proof treatment.

[Brief explanation of the drawing]

Fig. 1 shows the structure of a metal band heating device for a shrink-fit type explosion-proof cathode ray tube, which is an embodiment of the present invention; Fig. 2 shows the structure of a color picture tube; A diagram to explain how to attach a metal band to a cathode ray tube,
FIG. 4 is a diagram showing the structure of a conventional metal band heating device for a shrink-fit type explosion-proof cathode ray tube. 11... Metal band 16... High frequency induction coil 17... High frequency power supply part 21... Spiral coil 22... Ferrite 23... Air cylinder agent Patent attorney Norihiro Ogo 11 Principal A, ,・Total

Claims (1)

[Claims] Comprising a high-frequency power source and a high-frequency induction coil that heats a metal band with a current supplied from the high-frequency power source,
In a metal band heating device for a shrink-fit type explosion-proof cathode ray tube, which is comprised of a current-type inverter that uses a metal band heated by the high-frequency induction coil as a load of a parallel resonant circuit, a spiral coil is provided between the high-frequency power source section and the high-frequency induction coil. A magnetic member is arranged so as to be insertable inside the helical coil, so that the self-inductance of the high-frequency induction coil can be adjusted in accordance with changes in the load when heating the metal band. Features a metal band heating device for explosion-proof cathode ray tubes using a shrink-fitting method.