JPH06215904A - Composite positive characteristic thermistor device - Google Patents

Abstract

PURPOSE:To reduce balance current and electric power at operating by a method wherein smoothing conductivity is elevated in a surface of a PTC thermistor, in particular a contact surface with a common terminal. CONSTITUTION:In a composite positive characteristic thermistor device, a heating PTC thermistor element 30 and a current controlling PTC thermistor element 31 are arranged interposing a common terminal. In this composite positive characteristic thermistor device, plane grinding is applied to at least one surface of the PTC thermistors 30, 31, in particular a contact surface with the common terminal 32 and the degree of uneveness is 10mum or less. Thus, the heat generated by the heating PTC thermistor 30 is effectively conducted to the current controlling PTC thermistor 31 via the common terminal 32. Thus, it is possible to reduce balance current and electric power at operating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite positive temperature coefficient thermistor device used in a cathode ray tube (CRT) degaussing circuit of a color television or the like.

[0002]

2. Description of the Related Art A positive characteristic (PTC: Positive Tenpe) is used in a degaussing circuit of a shadow mask type CRT, a compressor motor starting relay circuit of a refrigerator or an air conditioner, or a protector circuit of a communication device where a current value needs to be gradually decreased.
(rature Coefficient) Thermistor is used.

A degaussing circuit of a shadow mask type color CRT, which is a typical example of using this positive temperature coefficient thermistor, will be described. The shadow mask, which is a main component of the shadow mask type color CRT, is provided immediately in front of the color CRT phosphor screen, and collides the electron beams emitted from the three electron guns with the corresponding phosphors. .

As a material used for the shadow mask, a thin steel plate is usually used in view of workability and cost. Therefore, the shadow mask may be magnetized by an external magnetic field or the like, and the course of the electron beam is bent by this magnetization, resulting in color misregistration, color unevenness, or screen fluctuation.

In order to prevent color misregistration, color unevenness or screen fluctuation caused by the magnetization of the shadow mask, a degaussing coil is provided on the outer periphery of the face plate, which is the front glass of the shadow mask type color CRT, near the shadow mask. The shadow mask is demagnetized by providing the degaussing coil with a gradually decreasing degaussing current.

In order to generate this gradually decreasing degaussing current, a positive temperature coefficient thermistor, a so-called PTC thermistor, is used. The PTC thermistor is an oxide semiconductor ceramic whose main component is barium titanate (BaTiO ₃ ), and the Curie point, which is the resistance change temperature, can be set arbitrarily by controlling the material composition. Used as a constant temperature heating element.

1A and 1B show the structure of the PTC thermistor, and FIG. 1C shows the resistance-temperature characteristic of the PTC thermistor. The shape of the PTC thermistor includes the case type shown in (a) and the lead type shown in (b).
In the case type shown in (a), the PTC thermistor element 10 is housed in the case 13 while being sandwiched between the terminals 11 and 12. The lead type shown in (b) has a structure similar to that of the case type.
The thermistor element and terminals are molded.

Shown in (c) is a resistance-temperature characteristic curve of the PTC thermistor. The resistance value of the PTC thermistor gradually decreases as the temperature rises while the temperature is relatively low, and the temperature is in front of the switching temperature. Minimum resistance value R _min
When the switching temperature is exceeded, the temperature rises sharply. Normally, the temperature at which the resistance value is twice R _min is the switching temperature. Like a PTC thermistor, the relationship between temperature and resistance is balanced by self-control. Therefore, P
If the resistance value of the TC thermistor in the stable state is increased and the TC thermistor is balanced in a short time, the equilibrium point current can be lowered and the power consumption can be reduced. The equilibrium point current depends on the initial resistance value of the degaussing element, and tends to increase toward the lower limit of the resistance standard range.

FIG. 2 shows an example of a degaussing circuit using this PTC thermistor.
A C thermistor 21 and a degaussing coil 23 attached around the face plate of the CRT 22 are connected in series, and a switch 24 for turning on / off the degaussing circuit is added. When a driving voltage is applied to the CRT 22, an AC current from the AC power supply 20 is applied to the degaussing circuit.
Degaussing is started by being supplied via the TC thermistor 21. The PTC thermistor 21 is self-heated and heated by the supplied alternating current, and when it reaches a predetermined switching temperature, the resistance value of the PTC thermistor 21 sharply increases and the alternating current sharply decreases, so that the degaussing operation is performed. To do.

If the resistance value of the degaussing PTC thermistor at the time of equilibrium is increased and the resistance value is reached in a short time, complete demagnetization can be performed by lowering the final equilibrium point current. In addition to being possible, it is possible to reduce the total power consumption. For this purpose, a composite positive temperature coefficient thermistor device composed of two PTC thermistors is used.

FIG. 3A shows the structure of the composite positive temperature coefficient thermistor device, and FIG. 3B shows the resistance-temperature characteristic of the composite positive temperature coefficient thermistor device. In the composite positive temperature coefficient thermistor device shown in (a), a heating PTC thermistor element 30 and a current control PTC thermistor element 31 are arranged with a common terminal 32 interposed therebetween, and terminals 33 and 34 are attached to each of them. The whole is stored in the case 35.

In (b), A is a resistance-temperature characteristic of the heating PTC thermistor 30, and B is a characteristic curve showing the resistance-temperature characteristic of the current controlling PTC thermistor 31. When an alternating current is applied in the circuit of FIG. 4, the PTC thermistor 3
0 and 31 self-heat and the temperature rises. The heat of the heating PTC thermistor 30 having a high heat generation temperature is generated by the common terminal 3
2, the current controlling thermistor is further heated and its temperature rises. For this reason, the state shifts to the equilibrium state R ₂ having a higher resistance value than the equilibrium state R ₁ when operated alone, so that the current is controlled to be smaller and the equilibrium point current becomes smaller.

The switching point temperature of the heating PTC thermistor 30 is higher than the switching point temperature of the current control PTC thermistor 31, and is set to be large in order to supply heat. Therefore, each switching temperature T _S
Are set to different values, for example, the switching temperature of the heating PTC thermistor 30 is set to 130 ° C., and the switching temperature of the current control PTC thermistor 31 is set to 50 ° C.

FIG. 4 shows the construction of a degaussing circuit using the composite type positive temperature coefficient thermistor device. In this degaussing circuit, an AC power source 40, a PTC thermistor 41 for current control and a degaussing coil 4 are provided.
2 is connected in series, and another PTC thermistor 43 for heating is connected in parallel with the PTC thermistor 41 for current control and the degaussing coil 42 connected in series, and the degaussing circuit is turned on / on. A switch 44 for turning off is added. In this degaussing circuit, C
An alternating current is supplied when a drive voltage is applied to the RT 42, and the heating PTC thermistor 44 generates heat, whereby the current controlling PTC thermistor 41 is heated to a higher temperature, and when the temperature reaches a predetermined temperature. The shadow mask is demagnetized by gradually decreasing the AC current flowing through the current control PTC thermistor 41.

The PTC thermistor, which is a ceramic, is manufactured by press-molding a granular material containing an organic binder into a predetermined shape with a mold and then firing it. Therefore, the surface of the finished product has very large irregularities. The unevenness difference is 15 μm to 30 μm, reaching an average of 18.4 μm.

In addition to evaporation of the organic binder during firing, softening may occur due to the high temperature during firing, which may cause bending. Therefore, the heating PTC thermistor 30
The adhesion between the common terminal 32 and the common terminal 32 and the PTC thermistor 31 for current control is poor, heat conduction through the common terminal 32 becomes insufficient, the equilibrium point current does not drop to a predetermined value, and demagnetization is insufficient. May become.

In order to reduce the final current of the current control PTC thermistor 31 to a predetermined equilibrium point current, the heating P
There is a method to raise the switching temperature of the TC thermistor 30, but a case 35 which is usually made of plastic is used.
There is a limit in terms of heat resistance.

[0018]

SUMMARY OF THE INVENTION It is an object of the present invention to improve thermal coupling (heat conduction) between a heating PTC thermistor and a common terminal and between a current control PTC thermistor and a common terminal in a composite positive temperature coefficient thermistor device. It is an object of the present invention to reduce the equilibrium point current and the power during operation.

[0019]

In order to solve the above problems, in the present application, the smoothness of the surface of a PTC thermistor used in a composite positive temperature coefficient thermistor device, particularly the surface in contact with a common terminal, is increased. That is, "a positive temperature coefficient thermistor device having a positive temperature coefficient thermistor for heating and a positive temperature coefficient thermistor for current control, characterized in that at least one of the positive temperature coefficient thermistors has a surface on the common terminal side that is planar-polished. The present invention provides a positive temperature coefficient thermistor device.

[0020]

In the present invention having such a structure, the heat generated from the heating PTC thermistor has a high smoothness and is efficiently passed through the common terminal in contact with the current control PTC.
Conducted by the thermistor.

[0021]

EXAMPLES Examples will be described. The same structure as the conventional one,
That is, a heating PTC thermistor with φ = 10 mm and t = 2.3 mm and a current control PT with φ = 14 mm and t = 2.0 mm.
Combined positive temperature coefficient thermistor device consisting of C thermistor
Only the heating PTC thermistor body has an average unevenness of 3.7.
Polished to have a thickness of μm. In the degaussing circuit shown in FIG. 4, this composite type positive temperature coefficient thermistor device is connected to an AC power source with an effective value voltage of 100 V, and a degaussing coil with an AC resistance of 5 Ω is connected to the equilibrium point current at energizing times of 30 seconds and 60 seconds. It was measured. On the other hand, in order to compare with this, the equilibrium point current was similarly measured for the conventional composite positive temperature coefficient thermistor device.

[0022]

[Table 1]

As a result, as shown in Table 1, the energization time is 30
The average value of the equilibrium point current in seconds is 3.9 for the conventional example.
What was 6 mAp-p in the embodiment of the present invention is 2.
98 mAp-p and 0.98 mAp-p decreased, and the average value of the equilibrium point current at a conduction time of 60 seconds was 2.96 for the conventional example.
What was mAp-p is 2.3 in the embodiment of the present invention.
It decreased by 5 mAp-p and 0.61 mAp-p.

This is because by reducing the unevenness due to the flat surface polishing, the thermal coupling is improved, and the current control PTC element equilibrium point resistance is increased.
It is shown that the surface of the C thermistor element is planarly polished to increase the heat conduction efficiency due to the thermal coupling between the heating PTC thermistor and the current control PTC thermistor, and the equilibrium point current can be reduced.

[0025]

The reduction of the equilibrium point current value tends to reduce the magnetization of the shadow mask of the CRT infinitely, and the image quality (color shift etc.) of the CRT is improved. Further, by reducing the large current in a short time, the image output of the CRT becomes stable in a very short time.
Further, the flat surface polishing improves the thermal coupling, makes it possible to reduce the variation in the equilibrium point current to a small level, and also improves the yield of resistance.

[Brief description of drawings]

FIG. 1 is a structural diagram of a PTC thermistor and a resistance-temperature characteristic diagram.

FIG. 2 is a degaussing circuit diagram using a PTC thermistor.

FIG. 3 is a structural diagram and a resistance-temperature characteristic diagram of a composite positive temperature coefficient thermistor device.

FIG. 4 is a degaussing circuit diagram using a composite type positive temperature coefficient thermistor device.

[Explanation of symbols]

 10,21 PTC thermistor 11,12,33,34 Terminal 13,35 Case 20,40 AC power supply 22 CRT 23,42 Degaussing coil 24,44 Switch 30,43 Heating PTC thermistor 31,41 Current control PTC thermistor 32 Common Terminal

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[Procedure amendment]

[Submission date] March 1, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

Shown in (c) is the resistance-temperature characteristic curve of the PTC thermistor. The resistance value of the PTC thermistor gradually decreases as the temperature rises while the temperature is relatively low, and when the temperature is the switching temperature. Minimum resistance value R _min
When the switching temperature is exceeded, the temperature rises sharply. Usually, the temperature at which the resistance value is twice R _min is the switching temperature. Like a PTC thermistor, the relationship between temperature and resistance is balanced by self-control. Therefore, P
If the resistance value of the TC thermistor in the stable state is increased and the TC thermistor is balanced in a short time, the equilibrium point current can be lowered and the power consumption can be reduced. The equilibrium point current depends on the initial resistance value of the degaussing element, and tends to increase toward the lower limit of the resistance standard range.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

The switching temperature of the heating PTC thermistor 30 is set higher than the switching temperature of the current control PTC thermistor 31 for the purpose of supplying heat. Therefore, the respective switching temperatures T _S are set to different values, for example, the switching temperature of the heating PTC thermistor 30 is set to 130 ° C., and the switching temperature of the current control PTC thermistor 31 is set to 50 ° C.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

This is because the thermal coupling is improved by reducing the unevenness due to the flat surface polishing, and the equilibrium point resistance of the current control PTC element is increased.
It is shown that by performing the surface polishing on the surface of the TC thermistor element, the heat conduction efficiency due to the thermal coupling between the heating PTC thermistor and the current control PTC thermistor is increased, and the equilibrium point current can be reduced.

Claims (2)

[Claims] 1. A composite type positive temperature coefficient thermistor device having a positive temperature coefficient thermistor for heating and a positive temperature coefficient thermistor for controlling current, wherein at least one of the positive temperature coefficient thermistors has a surface on the common terminal side that is subjected to planar polishing. Combined positive temperature coefficient thermistor device. 2. The composite positive temperature coefficient thermistor device according to claim 1, wherein the unevenness in the planar polishing is 10 μm or less.