JPS6025205A - Demagnetizing circuit - Google Patents

Abstract

PURPOSE:To eliminate an unnecessary remaining magnetic field after demagnetization and avoid disturbance of an image on a CRT by a method wherein a heat response member which is deformed by heat of a positive characteristics thermistor for heating to cut off a current applied to a series citcuit is connected the series circuit in series. CONSTITUTION:A series circuit is composed of a positive characteristics thermistor PTC3 for control and a demagnetizing coil L and connected to both ends of a source E. A positive characteristics thermistor PTC4 for heating is connected to the series circuit of the positive characteristics thermistor PTC3 for control and the demagnetizing coil L in parallel. A heat responsive member 5 is thermally connected to the positive characteristics thermistor PTC4 and connected to the series circuit of the positive characteristics thermistor PTC3 for control and the demagnetizing coil L in series. A bimetal, shape memory alloy or the like is used for the heat responsive member 5. For instance, the positive characteristics thermistor 3 for control, the positive characteristics thermistor 4 for heating and the heat responsive member 5 are united and housed in one case 1 to make an apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to degaussing circuits for cathode ray tubes in color televisions, computer monitor displays, and the like.

BACKGROUND OF THE INVENTION Demagnetization of a cathode ray tube is completed within a few seconds after the degaussing circuit starts being energized. If current continues to flow through the degaussing coil after degaussing is completed, it not only results in a loss of power consumption, but also causes an unnecessary magnetic field to remain, causing disturbances in the image on the cathode ray tube.

As shown in Fig. 1, a conventional degaussing circuit for a brush-thin tube has a positive characteristic resistor PTC for control at both ends of the power supply E.
I and the degaussing coil L are connected in series, and a heating positive characteristic leakage disk 1] TC2 is connected in parallel with this direct coil 11 circuit,
Generally, a control positive temperature coefficient resistor P T 01 and a heating positive coefficient thermistor PTC2 are thermally coupled. This circuit (゛ is a control positive characteristic thermistor p-rc
By setting the temperature of the heating positive temperature coefficient thermistor PTC2 as low as the temperature of the heating positive temperature coefficient thermistor PTC2, when electricity is started, first the control positive temperature coefficient thermistor I is set to a low value.
increases the resistance ([7) to limit the current to the degaussing coil L, and then increases the heating positive temperature coefficient thermistor PI-C2.
Next, heat the positive characteristic thermistor p-'rci for control, and heat the positive characteristic thermistor p-'rci for control C1.
1'·°; increase and demagnetize] further restrict the current to the coil L.

FIG. 2 shows the resistance of the control positive temperature coefficient thermistor P'l'CI and the heating positive coefficient thermistor PTC2 at a temperature of 1 (-1).
It is a figure which shows an example. For example, here, the Curie temperature of the control PTC thermistor PTC1 is set to 50°C, and the Curie temperature of the heating PTC thermistor PTC2 is set to 120°C.

However, in this conventional method, the heating positive temperature coefficient thermistor 1
) heated by Te3 to control positive characteristic 1 nermistor P
Even if the resistance value of TC1 increases, the positive control characteristic→nosmitter))1'CI does not become an insulator, and a slight (6) current continues to flow to the degaussing coil. This current leaves an unnecessary magnetic field in the degaussing coil, disturbing the image on the cathode ray tube. This is also a loss in power consumption.

In addition, in the conventional method, a control positive temperature coefficient thermistor 1) TC
In order to increase the resistance value of I as much as possible and to limit the current flowing through the degaussing coil as much as possible, a large type heating positive temperature coefficient thermistor PTC2 is used that generates a large amount of heat. Therefore, in order to prevent the heat of the heating PTC 4 no-mistor PTC2 from adversely affecting other circuit functions, the heating PTC thermistor P]-C2 and the control PTC thermistor 1)-r
14 people thermally bonded with Cl in an insulated case,
Sometimes there were restrictions on placement.

Purpose of the Invention The purpose of the present invention is to completely cut off the current to the degaussing coil within a few seconds after the start of energization, to prevent unnecessary magnetic fields from remaining, and to create a heating positive coil that is smaller than conventional ones. An object of the present invention is to provide a degaussing circuit for cathode ray tubes used in color televisions, computer monitor displays, etc., which can use a lenometer.

Summary of the Invention To summarize this invention, in a degaussing circuit in which a series circuit of a limiting positive temperature coefficient thermistor and a degaussing coil is connected to both ends of a power supply, and a heating m19j1 bamboo no mistor is connected in parallel with this series circuit, a heating This is a degaussing circuit in which a thermally responsive body that is deformed by the heat of the positive I11 reamister and interrupts the current in the series circuit l\ is connected in series with the series circuit.

The present invention will be described in detail below with reference to the drawings.

DESCRIPTION OF EMBODIMENTS FIG. 3 is a circuit diagram showing an embodiment of the extinguisher circuit of the present invention. PTC3 is a control positive temperature coefficient thermistor;
It forms a series circuit with the degaussing coil [and is connected to both ends of the power supply E. PTC4 is a positive temperature coefficient thermistor for heating, and PTC3 is a positive temperature coefficient 1 no mister for control and demagnetization:
1 is connected in parallel with the series circuit with L. 5 is a thermally responsive body, which is a positive temperature coefficient thermistor PTC4 for heating.
It is thermally coupled with the control positive temperature coefficient thermistor PTC3.
and the degaussing coil L are connected in series.

For the thermally responsive body 5, bimetal, shape memory alloy, or the like is used. FIG. 4 is a diagram showing an example of the resistance temperature characteristics of the control positive temperature coefficient thermistor PTC3 and the heating positive coefficient thermistor PTC4. For example, here, the Curie temperature of the control PTC thermistor PTC3 is set to 50°C, and the Curie temperature of the heating PTC thermistor Te3 is set to 80°C.

The heating positive characteristic I nermistor PTC4 used in the degaussing circuit of the present invention is designed to heat deformation of the thermally responsive body 5, and has a higher resistance to heating than the one used in the degaussing circuit of 1. The degree can be set low.

First, approximately 5 seconds after the start of energization to the degaussing circuit, the control positive characteristic resistor I)-1-C3 increases the resistance, limits the current to the degaussing coil, and demagnetizes it. Let's do it. While the resistance value of control positive temperature coefficient thermistor)) Te3 is 1, the heating m1Q4j ('L (J-Mister PT
Current also flows through C4 and generates heat, and after a certain period of 115 minutes, this heating positive temperature coefficient thermistor PTC4 also reaches a stable operating point.

The thermally responsive body 5 is heated by the positive temperature coefficient thermistor PT04 for heating, deforms, and becomes the positive temperature coefficient thermistor P for the control 11.
Cut off the current to the series circuit of TC3 and degaussing coil l-. As a result, after the degaussing is completed, no current flows through the degaussing coil L for 4f.

FIG. 5 is a sectional view showing a 14M construction example in which a control PTC thermistor, a heating PTC thermistor, and a thermally responsive body used in the degaussing circuit of the present invention are housed in one case and integrated into a device. It is. Reference numeral 1 denotes a case, which has two abutments 411J and 12 (11) and 12 (11) and 12, respectively, which protrude toward the center of the case 1 on the inner wall surface of the same number. An end a of a pair of opposing inner wall surfaces parallel to the locking piece 2 of the case 1 and one end C of the spring terminal 7 are each led out of the case 1. Furthermore, terminals 8 are installed on two opposing locking pieces 2 on the side closer to the surface on which the rear spring terminals 7 of the four locking pieces 2 are installed. One end of the spring terminal 8 is led out of the case 1. Reference numeral 3 designates a positive temperature coefficient thermistor for control, which is pressed and held between the spring terminals and the locking piece 2 by the spring properties of the spring terminals, and connects one electrode of the positive temperature coefficient thermistor 3 for the recessed part to the spring terminal. It is electrically connected to C by 1a. Reference numeral 4 denotes a heating positive temperature coefficient thermistor, which is compressed and held between a terminal 8 set on the L piece 2 side and a spring terminal 7 by the spring property of the spring terminal 7, and has a positive temperature coefficient thermistor for heating. One electrode of the mister 4 is electrically connected to the terminal 8, and the other electrode and the spring terminal 7 are electrically connected. Reference numeral 5 designates a thermally responsive body in the shape of a letter 7, the - side of which is fixed to the terminal 8 by, for example, welding, and is also electrically connected to the terminal 8. For example, bimetal is used for the thermally responsive body 5. The thermally responsive body 5 is in contact with the electrode of the control PTC thermistor 3 at room temperature, and conducts between the terminal 8 and the control PTC thermistor 3, but is heated by the heating PTC thermistor 4. As a result, it deforms and separates from the electrode of the positive temperature coefficient thermistor 3 for control, completely cutting off the current between the terminal 8 and the positive temperature coefficient 1 non-mistor 3 for control.

One end a of the spring terminal 6, one end b of the terminal 8, one end C of the spring terminal 7 derived from the case 1 of the )14 model is the third
a-b-1 of the diagram showing an embodiment of the degaussing circuit of the present invention in the figure.
c-, respectively.

In other words, at the start of energization, the thermal response (A5 is in contact with the control thermistor 3, so a predetermined current flows through the degaussing coil), but after the degaussing is completed, the heat of the heating positive thermistor 4 is released. As a result, the thermally responsive body deforms and separates from the control positive characteristic reamister 3, cutting off the current to the demagnetizer 1.

The above is a device in which the fli control thermistor 3, heating positive temperature coefficient thermistor 4, and thermally responsive body 5 used in the degaussing circuit of the present invention are integrated and housed in a case 1.
Although this is a VJ example, the method of H assimilation is not limited to this one structural example, and it goes without saying that changes may be made within the scope of not impairing the debt of the present invention. In particular, for the thermally responsive body 5, a shape memory alloy or the like may be used instead of bimetal, and its shape is not limited to the V-shape. The shape of the locking pieces 2 is also arbitrary, and is limited to two locking pieces 2 each protruding toward the center of the case 1 from the opposing inner wall surfaces, as in this structural example. It is not something that will be done.

Effects of the Invention The degaussing circuit of the present invention configured as described above increases the resistance value of the i1i control positive temperature coefficient thermistor and limits the current to the degaussing coil to complete degaussing. Positive Thermal Characteristics - The thermally responsive body heated and deformed by the misc completely cuts off the current to the demagnetized file, so no unnecessary magnetic field remains after demagnetization is completed, which can cause disturbances in the picture on the cathode ray tube. I have never had one.

Furthermore, after the current to the degaussing coil is cut off, the power consumption of this degaussing circuit is limited to the consumption of the positive temperature coefficient thermistor for heating, so that there is little heat loss. Moreover, the purpose of the heating PTC thermistor used in the degaussing circuit of the present invention is not to heat the control PTC thermistor to increase its resistance value as in the conventional case, but to heat deformation of the thermally responsive body. Because it is designed for the purpose of extinguishing f! i
Since it is possible to use a compact device with a small electric nozzle, power consumption can be further reduced.

Furthermore, the heat generated by the heating PTC thermistor used in the degaussing circuit of the present invention can be made smaller than the heat generated by the heating PTC thermistor used in the conventional degaussing circuit. The heat-resistant design of each constituent part is easy. In addition, the degaussing circuit of the present invention does not have an adverse effect on other circuit functions due to heat. There are no restrictions on placement.

Furthermore, the control positive temperature coefficient thermistor used in the degaussing circuit of the present invention is energized for only a few seconds after the degaussing circuit starts being energized, whereas in the conventional case, it continues to be energized throughout the operation of televisions, computer monitor displays, etc. This is much shorter than the energization time of the control downstream 1J1 thermistor used in the degaussing circuit.

Therefore, the control lower Q4j thermistor used in the degaussing circuit of the present invention is similar to the control tall I thermistor used in the conventional degaussing circuit.
Longer life than IJ positive characteristic 4 no mister.

[Brief explanation of the drawing]

Fig. 1 shows a conventional degaussing circuit, Fig. 2 shows a resistance temperature characteristic diagram of a control PTC thermistor and a heating PTC thermistor, and Fig. fjS3 shows an embodiment of the demagnetizing circuit of the present invention. The figure shown in Fig. 4 is the lower 1 for control. Resistance of i-characteristic 4 no-mister and positive-characteristic thermistor for heating! iii'1 degree characteristic diagram,
Force characteristic diagram Positive characteristic thermistor for control and pressure for heating 1'!
(2) It is a cross-sectional view showing an example of a structure in which a rigid mister and a heat-responsive Iho are integrated into a device. 3...Positive characteristic force for control - Mister, 4...
・Positive characteristic thermistor for heating, 5... thermally responsive body.

Claims (1)

[Claims] In the degaussing circuit, in which a series circuit of a control positive temperature coefficient thermistor and a degaussing coil is connected to both ends of the power supply, and a heating positive coefficient thermistor is connected to the direct 11 circuit and the parallel 11 circuit, the heat of the heating positive coefficient thermistor is A degaussing circuit characterized in that a thermally responsive body that deforms to interrupt current flow to the series circuit is connected in series with the series circuit.