JPH04155901A - Ptc thermistor for demagnetization circuit - Google Patents

Abstract

PURPOSE:To manufacture the device with smaller number of components and by smaller number of assembly processes and to reduce a residual current after the device finishes a demagnetizing operation by uniting PTC thermistor for controlling a transient-decay current and a PTC thermistor for a heater in a body. CONSTITUTION:A ring-shaped PTC thermistor for a heater 35 whose inner diameter is nearly the same with the diameter of a PTC thermistor for controlling a transient-decay current 33 is located around the PTC thermistor 33 having the disk like shape. At that time, two PTC thermistors 33 and 35 are set in each other. Therefore, the PTC thermistor for controlling a transient-decay current 33 and the PTC thermistor for a heater 35 are united into one body. On one side of each of the PTC thermistors 33 and 35, electrodes 37 and 38 are baked respectively. And, terminals 41 and 42 are mounted to the electrodes 37 and 38 respectively. On the other side of the PTC thermistors 33 and 35, an electrode 39 is baked. And, a terminal 43 is mounted to the electrode 39. The whole body of the united device except for a part of the terminals 41, 42 and 43 is molded with resin.

Description

[Detailed description of the invention] The present invention is a PTC (positive T
Regarding emperor-ture Coefficient thermistors, more specifically PTC for degaussing circuits for degaussing shadow masks of color television receivers.
Regarding thermistors.

Generally, color television receivers are equipped with an automatic demagnetization circuit to automatically demagnetize the shadow mask, since convergence and purity deteriorate when the shadow mask of the cathode ray tube becomes magnetized.

FIG. 3 shows an example of the configuration of a conventionally used automatic degaussing circuit. As shown in FIG. 3, in this degaussing circuit, a degaussing coil 12 and a PTC thermistor 13 for attenuation current control are connected in series to an AC power supply 11, and when the power switch 13 is turned on, the PTC thermistor for attenuation current control 1
A current flows through the demagnetizing coil 12 through the degaussing coil 12, and the residual magnetism of the shadow mask of the cathode ray tube is demagnetized. Further, when the current flows, the resistance value rapidly increases due to self-heating of the attenuation current control PTC thermistor 13, the value of the current attenuates, and the demagnetizing operation ends. Even after the degaussing operation is completed, a small amount of current flows through the degaussing coil 12, but if the current is large, screen disturbances such as screen shaking are likely to occur. Therefore, the attenuation current control PTC thermistor 13
A heater PTC thermistor 15 is provided in the vicinity of the heater PTC thermistor 15, and the heater PTC thermistor 15 is connected in parallel to the AC power supply 11, that is, to the degaussing coil 12 and the attenuation current control PTC thermistor 13. When the power switch 14 is turned on, current is also supplied to the heater PTC thermistor 15 to cause the heater PTC thermistor 15 to generate heat, and this heat is transferred to the attenuation current control PTC thermistor 13, thereby reducing damping when stable. The resistance value of the current control PTC thermistor 13 is increased to a high resistance state, thereby minimizing the current flowing through the degaussing coil 12.

The PTC thermistor 13 for attenuation current control and the PTC thermistor 15 for the heater described above are actually incorporated into the automatic degaussing circuit as the PTC thermistor 16 for the degaussing circuit as shown in FIG. , PTC thermistor 1 for heater
The heat generated from 5 is attenuated by PTC thermistor 13 for current control.
This makes it easier for people to communicate. In other words, PTC for degaussing circuit
The thermistor 16 is a two-piece C thermistor 1 for attenuation current control.
3. PTC thermistor for heater 15, electrode 17.18.
19 and a resin case 20 enclosing these, and the electrode 17 and the electrode 19 provide a
TC thermistor 13 and PTC thermistor 15 for heater
One side of the electrode 18 is in pressure contact with the electrode 18 .

However, as described above, this PTC thermistor 16 for the degaussing circuit has a problem that not only the number of parts is large, the size of the element becomes large, but also the number of assembly steps is increased.

Furthermore, since the attenuation current control PTC thermistor 13 and the heater PTC thermistor 15 are only in pressure contact with the electrodes 17 and 19, there is a risk that the elements may fall apart inside the resin case 20 due to vibrations, impacts, etc. It also had the problem of lack of reliability.

The present invention has been made in view of the above-mentioned problems, and provides a PTC thermistor for a degaussing circuit that can be manufactured with a small number of parts and an assembly process, has little residual current after the end of degaussing operation, and has improved reliability. It is intended to.

In order to achieve the above object of 711, a PTC thermistor for a degaussing circuit according to the present invention is a PTC thermistor for a degaussing circuit configured by connecting a PTC thermistor for attenuation current control and a PTC thermistor for a heater in parallel. The PTC thermistor is characterized in that a plate-shaped attenuation current control PTC thermistor and a ring-shaped heater PTC thermistor are fitted and integrated.

According to the configuration described above, the attenuation current control PTC thermistor has a plate shape, and the heater PT has a ring shape.
Since the C thermistor is fitted and integrated, the number of parts is significantly reduced, and the number of assembly steps is accordingly reduced. Further, by fitting the attenuation current control PTC thermistor with the heater PTC thermistor, a decrease in reliability of the element due to vibrations, shocks, etc. is prevented, and the heat of the heater PTC thermistor is transferred to the attenuation current control PTC thermistor. This results in efficient transmission to the PTC thermistor.

Normally, when a PTC thermistor for degaussing circuit is incorporated into an automatic degaussing circuit, when an alternating current of, for example, i oov flows through it, the PTC thermistor for attenuation current control self-heats, and the resistance value of this element itself increases. The current decays. At this time, the temperature of the PTC thermistork for attenuation current control reaches equilibrium at a temperature where the amount of heat generated by self-heating and the amount of heat escaping from the element body are balanced. The attenuation current continues to attenuate as shown in FIG. 2(a) until the equilibrium temperature is reached, and at the equilibrium temperature the attenuation current also becomes balanced. Further, as the attenuation current attenuates, the residual magnetism of the shadow mask also decreases as shown in FIG. 2(b).

As described above, in the PTC thermistor for a degaussing circuit according to the present invention, the heat of the PTC thermistor for the heater is efficiently transferred to the PTC thermistor for controlling the decay current, so that the equilibrium temperature of the PTC thermistor for controlling the decay current further increases. Become. Therefore, the resistance value of the PTC thermistor for controlling the decay current increases, and the residual current at the equilibrium temperature becomes smaller.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a PTC thermistor for a degaussing circuit according to the present invention will be described based on the drawings. Note that components having the same functions as those of the conventional example are given the same reference numerals.

FIGS. 1(a) and 1(b) are a plan view and a back view, respectively, schematically showing an embodiment of a PTC thermistor for a degaussing circuit according to the present invention, and 33 in the figure has a substantially disk shape. A PTC thermistor for attenuation current control is shown. Around this attenuation current control PTC thermistor 33, a ring-shaped heater PTC thermistor 3 having an inner diameter approximately the same size as the diameter of the attenuation current control PTC thermistor 33 is provided.
5 is disposed in such a manner that it fits into the PTC thermistor 33 for attenuation current control.
The C thermistor 33 and the heater PTC thermistor 35 are integrated.

Integrated PTC thermistor 33 for damping current control
and electrodes 37 and tt! on one side of the heater PTC thermistor 35, respectively. i38 is baked in,
A terminal 41.42 is attached to each electrode 37.38. Further, on the entire other side of the attenuation current control PTC thermistor 33 and the heater PTC thermistor 35, electrodes 3
9 is baked in, and a terminal 43 is attached to the electrode 39 in the same manner as above.

All of the terminals 41, 42, and 43 except for a part are molded with resin (not shown) to form a PTC for degaussing circuit.
A thermistor 36 is configured.

In this way, in the degaussing circuit PTC thermistor 36 according to the above embodiment, the attenuation current control PTC thermistor 3
3 and the heater PTC thermistor 35 are fitted and integrated, so it can be manufactured with a small number of parts and with a small number of assembly steps. Further, by fitting the attenuation current control PTC thermistor 33 and the heater PTC thermistor 35 and by resin molding, it is possible to prevent a decrease in reliability of the element due to vibrations, shocks, etc.

In addition, in the PTC thermistor 36 for the degaussing circuit described above, the attenuation current control PTC thermistor 33 and the heater PTC thermistor 35 are integrated and resin molded, so that heat is easily trapped in the resin mold, and the heater The heat of the PTC thermistor 35 for current control P
It is efficiently transmitted to the TC thermistor 33. Therefore, when the degaussing circuit PTC thermistor 36 is incorporated into an automatic degaussing circuit as shown in FIG. 16 above the equilibrium temperature. As a result, the resistance value of the decay current control PTC thermistor 33 increases, and the residual current at the equilibrium temperature decreases.

Table 1 shows PTC thermistor 3 for degaussing circuit according to this embodiment.
This figure shows the results of a characteristic comparison experiment when the conventional PTC thermistor 16 for a degaussing circuit shown in FIGS. 6 and 4 was incorporated into the automatic degaussing circuit shown in FIG. 3.

Table 1: PTC thermistor 36 for degaussing circuit according to this embodiment
and the conventional PTC thermistor 16 for the degaussing circuit, Ts = 60°C, Ra1t = 5Ω, and the PT for the heater
Both the C thermistor 15 and the heater PTC thermistor 35 have Ts=130° C. and R2s:=l 50Ω.

However, here, Rzsz: resistance value of the PTC thermistor at room temperature (25°C) Ts: resistance value of the PTC thermistor is the resistance value at room temperature R2,1
(switching temperature), and the element dimensions of the degaussing circuit PT (,9-mister 36) according to this embodiment are 1.5 mm in thickness and LB mm in outer diameter.

As is clear from Table 1, the PTC thermistor 36 for a degaussing circuit according to this embodiment has a large inrush current and a small residual current compared to the conventional product. This result also shows that integrating the PTC thermistor 33 for attenuation current control and the PTC thermistor 35 for the heater and molding them with resin will efficiently transfer the heat of the PTC thermistor 35 for the heater to the PTC thermistor 33 for attenuation current control, and increase the equilibrium temperature. It can be seen that this method is effective in reducing the residual current.

As is clear from the above explanation, the PTC thermistor for a degaussing circuit according to the present invention includes a plate-shaped PTC thermistor for attenuation current control and a ring-shaped PTC thermistor for heating. Since they are fitted and integrated, they can be manufactured with fewer parts and fewer assembly steps. In addition, the attenuation current control PTC
By fitting the thermistor with the PTC thermistor for the heater, the reliability of the element can be improved and the residual current after the degaussing operation is completed can be reduced.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are a plan view and a back view schematically showing an embodiment of a PTC thermistor for a degaussing circuit according to the present invention, and FIG. 2(a) is a damping flow flowing through a degaussing coil. A waveform diagram showing the state of the current, Figure 2 (b) is shown in Figure 2 (
Figure 3 is a circuit diagram showing a configuration example of a conventional automatic degaussing circuit, and Figure 4 is a circuit diagram showing a configuration example of a conventional automatic degaussing circuit. FIG. 2 is a cross-sectional view schematically showing an example of a PTC mister for a degaussing circuit. 33... PTC thermistor for attenuation current control 35...
PTC thermistor for heater 36... PTC thermistor for degaussing circuit Patent applicant:
Sumitomo Metal Industries Co., Ltd. Agent/Patent Attorney Ryuji Bennai Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) PTC thermistor for attenuation current control and PT for heater
In a PTC thermistor for a degaussing circuit configured by connecting a C thermistor in parallel, a PTC thermistor for attenuation current control having a plate shape and a PTC thermistor for a heater having a ring shape are fitted and integrated. A PTC thermistor for degaussing circuits.