JP3449337B2 - Degaussing device and degaussing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a degaussing device and a degaussing method, and more particularly to degaussing a shadow mask provided in a picture tube using a degaussing current generated based on a current supplied from a DC power source. Degaussing device and degaussing method.

[0002]

2. Description of the Related Art Conventionally, as a degaussing device utilizing a degaussing current generated based on a current supplied from an AC power source,
A degaussing device disclosed in Japanese Patent Publication No. 4-39269 is known. This type of degaussing device supplies a degaussing current having a decaying AC voltage waveform to a degaussing coil to degauss a shadow mask. However, when the picture tube is mounted on a vehicle-mounted television set or a portable television set, it is unavoidable to use a battery power source to generate a degaussing current. This type of degaussing device charges a capacitor based on the current supplied from a DC power source, uses the discharge of the capacitor to generate a degaussing current, which is a short-cycle AC current, and uses this degaussing current in a degaussing coil. It is supplied to demagnetize the shadow mask. At that time, since it is difficult to make the positive and negative peak current values of the degaussing current the same, there is residual magnetism in the shadow mask.

[0003]

In the conventional degaussing device that generates a degaussing current based on the current supplied from the DC power source, the electron of the picture tube is caused by the characteristic of the picture tube device itself in which the degaussing device is installed. The deviation of the irradiation position of the beam cannot be corrected, which may cause deterioration of the purity. Further, JP-A-2-214288, JP-A-61-33574, JP-A-3-638.
The device disclosed in Japanese Patent No. 8 can detect and correct the external magnetic field, but cannot correct the deviation of the irradiation position of the electron beam of the picture tube due to the characteristic of the picture tube device itself. In addition, the one disclosed in JP-A-2-268583 can limit the magnetic emission from the picture tube, but the same problem is not solved.
The present invention has been made in view of the above problems, and irradiates an electron beam of a picture tube by the characteristic of the picture tube device itself.
It is possible to reduce the displacement of the position ,
The irradiation position of the electron beam can be adjusted with a simple circuit.
An object of the present invention is to provide a degaussing device and a degaussing method that can be performed.

[0004]

In order to achieve the above object, the invention according to claim 1 provides a power supply line of a DC power supply.
A current limiting resistor connected at one end and the other end of this resistor
And a variable capacitor connected between
Input to the connection part of the anti- and same variable capacitor and ground
It has a connector connected to the
The variable capacitor from the power line through the resistor
Accumulates electric charge on the variable capacitor and discharges it when the power is turned off.
The uses and demagnetizing current generating circuit for generating a demagnetizing current is an alternating voltage waveform of the short cycles, it is attached to the picture tube, both ends
Is connected to the output side of the connector and is supplied with the degaussing current, and the electron beam irradiation surface of the picture tube is narrowed.
Comprising a degaussing coil wound Mari eyes or direction to reduce the tendency of the spread first, the degaussing current generating circuit
Is when the power stored in the variable capacitor is turned off.
Supply to the degaussing coil via the connector
The positive and negative peak currents are made variable when the power is turned off by
It is configured to generate a degaussing current .

In the invention according to claim 1 configured as described above, when the power is turned on, the current is controlled from the power line.
Power is supplied through a limited resistor and a variable capacitor
Accumulates charge. Then, when the power is turned off,
The capacitor transfers the accumulated charge to the degaussing coil through the connector.
Supply. At that time, with the variable capacitor and degaussing coil
Since the resonance circuit is configured, the current flowing through the degaussing coil is
The AC voltage waveform has a short cycle. The degaussing current generation circuit generates a degaussing current having a short cycle AC voltage waveform by using the discharge of the variable capacitor when the power is off, and supplies the degaussing coil to the degaussing coil mounted on the picture tube. Then, the degaussing coil generates a magnetic flux according to the AC voltage waveform of the degaussing current,
Degaussing the shadow mask provided on the picture tube.
At that time, since it is difficult to make the positive and negative peak current values of the degaussing current the same, magnetism remains in the shadow mask. Here, the degaussing coil is the electron beam irradiation surface of the picture tube.
Since it is wound in such a direction that the tendency of narrowing or widening of the electron beam is reduced, the irradiation position of the electron beam is adjusted in the direction in which the deviation is reduced. Therefore, it becomes possible to reduce the deviation of the irradiation position of the electron beam of the picture tube due to the characteristic of the picture tube device itself, and to prevent the deterioration of the purity and the like. Also, for variable capacitors
The resonance frequency of the resonance circuit changes according to the capacitance,
The peak current of the flow also changes. Therefore, the variable conden
The peak current of the degaussing current can be changed by changing the capacitance of the
Variable circuit that can be changed with a simple circuit
Can be configured. The variable circuit is
If the peak current is changed, the degaussing current generation circuit will
Supply this degaussing current to the coil. Where shadow mass
The residual magnetic strength of the magnet is the peak current of the degaussing current.
It depends on the size of the
The adjustment amount of the electron beam irradiation position is determined. Therefore,
Change the positive and negative peak current of degaussing current with variable circuit
This makes it possible to adjust the irradiation position of the electron beam.
is there.

[0006] Here, as an example of a specific configuration of erasure current generating circuit, the invention according to claim 2, in degaussing apparatus according to claim 1, the connector is on the input side
On the other hand, the detachable connector whose mounting direction on the output side is variable
It is configured as a connector . In the invention according to Claim 2 as constructed above, when such design changes, it is possible to easily change the direction of adjustment of the irradiation position of the electron beam.

As another example of the configuration of the degaussing current generating circuit, a current whose one end is connected to the power supply line of the DC power supply is used.
Connect a limiting resistor between the other end of this resistor and ground.
Connected variable capacitor, same resistance and same variable capacitor.
Switching with the connection of the sensor and ground connected to the input side
Switch and has the above power line when the power is turned on.
Charge is accumulated in the variable capacitor through the resistor from
However, when the power is turned off, the discharge of the variable capacitor is used to
Degaussing that produces a degaussing current that is the alternating voltage waveform of a cycle
Attached to the current generation circuit and the picture tube, both ends switch as above
Connected to the output side of the switch to supply the above degaussing current.
And the surface of the cathode ray tube where the electron beam was irradiated narrowed.
Wrap in a direction that reduces the tendency of the eyes or spread eyes
And a degaussing current generating circuit,
When the power is turned off, the charge accumulated in the variable capacitor is
Supply to the above degaussing coil via the changeover switch
This made the positive and negative peak currents variable when the power was off.
The degaussing current may be generated. As above
In the invention configured as described above, it is possible to prevent forgetting to attach the connector.
The circuit configuration is suitable for giving priority.

[0008]

[0009]

As described above, the method for performing degaussing is not necessarily limited to a substantial device. As an example, the invention according to claim 3 is a power source line of a DC power source.
The current limiting resistor connected at one end to the
A variable capacitor connected between the other end and ground,
The connection of the same resistance and the same variable capacitor and the ground
It has a connector connected to the input side and the power is on
From the power line to the variable capacitor via the resistor.
The charge is stored in the sensor and the
Degaussing is a short-cycle AC voltage waveform using discharge.
Degaussing current generating circuit that generates a current and is attached to the picture tube,
Both ends are connected to the output side of the above connector and the above degaussing current
And the electron beam irradiation surface of the same picture tube
Direction to reduce the tendency of narrowing or widening of
With the degaussing coil wound around the
Degaussing method for degaussing a shadow mask
When the power is turned off, the charge accumulated in the variable capacitor is
By supplying the degaussing coil through the connector
Degaussing with a positive and negative peak current variable when the power is turned off
It is configured to generate a current and execute the demagnetization of the shadow mask. That is, it is needless to say that the method is not limited to a substantial apparatus and is effective as a method thereof, and the apparatus configuration described in claim 2 can be applied to the method.

[0011]

As described above, according to the present invention, the irradiation position of the electron beam of the picture tube by the characteristic of the picture tube device itself.
Shift with it is possible to the reduce of simple
It is possible to provide a degaussing device capable of adjusting the irradiation position of the electron beam with various circuits . Further, according to the invention of claim 2, when the design is changed, the electron beam
It is possible to easily change the adjustment direction of the irradiation position .
Further, according to the invention of claim 3, the picture tube device itself is
The electron beam irradiation position of the picture tube depends on the characteristics of the body.
It is possible to reduce the amount of
It is possible to adjust the irradiation position of the electron beam on the road.
A magnetic method can be provided.

[0012]

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a main configuration of a degaussing device according to an embodiment of the present invention. In the figure, the degaussing device is supplied with DC power from a battery 40 of the picture tube device, the degaussing coil 10 according to the present invention is mounted around the picture tube 30 of the picture tube device, and disposed inside the picture tube 30. The degaussing of the shadow mask is performed.

The picture tube 30 has a fluorescent screen inside the front surface, and a predetermined image is projected by irradiating a predetermined position on the fluorescent screen while blocking an electron beam emitted from an electron gun with a shadow mask. There is. At this time, if the shadow mask is magnetized, the electron beam emitted from the electron gun deviates from the original traveling direction in the vicinity of the shadow mask, which causes color unevenness in the projected image. Therefore, the degaussing coil 10 is attached to the picture tube 30, and the shadow mask is degaussed by the magnetic flux generated in the degaussing coil 10 to prevent color unevenness of the image.

Here, if the picture tube device is capable of using an AC power supply, it is possible to supply a degaussing current to the degaussing coil by using the AC power supply. At that time, a sufficient degaussing effect can be obtained by generating a degaussing current having a decaying alternating current waveform. However, when the picture tube is installed in a vehicle-mounted or portable television device, the degaussing current must be generated by using the DC power supply supplied from the battery and supplied to the degaussing coil. .
Therefore, as shown in FIG. 1, the degaussing current generating circuit 20 according to the present invention is provided.

The degaussing current generating circuit 20 includes a battery 40
The current limiting resistor R1 having one end connected to the power supply line 41, the variable capacitor C1 connected between the other end of the resistor R1 and the ground, and the generated degaussing current are supplied to the degaussing coil 10. A detachable connector 21 which is a connecting portion is provided. The input side 21a of the connector 21 is connected to the connecting portion 2 of the resistor R1 and the variable capacitor C1.
2 and the ground, and the output side 21b is connected to both ends of the degaussing coil 10.

When the connector 21 is connected and the power is turned on, electric power is supplied from the power supply line 41 to the variable capacitor C1 via the resistor R1 and electric charges are accumulated. And
When the power is turned off, the degaussing coil 10 receives the charge accumulated from the variable capacitor C1 from the connection portion 22 to the connector 21.
Is supplied via. Here, when the power is off, the variable capacitor C1 and the degaussing coil 10 form a resonance circuit,
The degaussing current flowing through the degaussing coil 10 has a short-cycle AC voltage waveform.

Since this degaussing current utilizes the discharge of the variable capacitor C1, there is a difference between the positive and negative peak currents. Then, magnetic fluxes are generated in the degaussing coil 10 according to different peak currents of positive and negative, so that magnetism remains in the shadow mask. It is possible to change the positive and negative peak currents by changing the circuit by adding components to the degaussing current generation circuit 20, but it is difficult to make the peak currents the same for positive and negative.

Here, depending on the winding direction of the degaussing coil 10 attached to the picture tube 30, the irradiation surface 31, which is the irradiation position of the electron beam of the picture tube 30, becomes narrow as shown in FIG. Magnetism remains in the shadow mask so that the irradiation surface is widened as shown in FIG. Note that the example of FIG. 2 shows that the irradiation surface 31 becomes a narrowed portion when the peak current flowing through the degaussing coil 10 is clockwise, and the example of FIG. 3 is when the peak current is counterclockwise. It is shown that the irradiation surface 31 becomes a spread eye. Since the residual magnetism of the shadow mask depends on the magnitude of the peak current, the irradiation surface 31 becomes narrow when the direction of the maximum peak current flowing through the degaussing coil 10 is clockwise, and when the peak current is counterclockwise, the irradiation surface 31 is counterclockwise. 31 becomes a narrowing eye.

By the way, the picture tube to which the degaussing coil is attached has a tendency that the irradiation surface as a whole tends to be narrowed or widened if the same type of the same manufacturer is used due to its own characteristics. Or Further, even in a picture tube device in which a degaussing device is installed, due to magnetic flux leakage from the flyback transformer or the like, the irradiation surface as a whole tends to be narrowed depending on the layout of the board such as the layout of the flyback transformer, It tends to spread. As described above, depending on the substrate layout, the type of the picture tube, and the like, whether the electron beam irradiation surface of the picture tube tends to be narrowed or widened. Therefore, the degaussing coil 10 is wound in such a direction as to reduce the tendency of narrowing or widening. For example, in the picture tube device in which the irradiation surface 31 of the electron beam has a narrowed characteristic, the degaussing coil 10 may be wound so that the maximum peak current flows in the direction illustrated in FIG. On the other hand, in the picture tube device in which the irradiation surface 31 has the characteristic of widening, the degaussing coil 10 may be wound so that the maximum peak current flows in the direction illustrated in FIG.

When the degaussing current generating circuit 20 generates a degaussing current and supplies it to the degaussing coil 10, the degaussing coil 10 causes residual magnetism in the shadow mask so as to reduce the deviation of the irradiation surface 31. Then, the irradiation surface 31 changes according to the residual magnetism of the shadow mask, and the deviation of the irradiation surface 31 due to the characteristics of the picture tube device is reduced. Therefore, the degaussing coil 10 and the degaussing current generating circuit 20 can reduce the deviation of the irradiation position of the electron beam of the picture tube due to the characteristics of the picture tube device itself. Can be prevented.

In this embodiment, since the direction of the degaussing current flowing through the degaussing coil 10 can be switched,
The mounting direction of the output side 21b with respect to the input side 21a of the connector 21 is variable. Then, when changing the substrate layout of the picture tube device in which the degaussing device is installed or the type of the picture tube, the adjustment direction of the irradiation position of the electron beam can be easily changed. Of course, in order to be able to switch the direction of the degaussing current flowing through the degaussing coil, it is not necessary to use a removable connector,
You may use the changeover switch 71 as shown in FIG. In this case, since it is not necessary to remove the connector when switching the direction of the degaussing current, the circuit configuration is suitable when the emphasis is placed on preventing forgetting to mount the connector.

The variable capacitor C1 provided in the degaussing current generating circuit 20 can change its capacitance. When the capacitance of the variable capacitor C1 changes, the variable capacitor C1
Since the resonance frequency of the resonance circuit constituted by 1 and the degaussing coil 10 changes, the peak current of the degaussing current changes according to the capacitance of the variable capacitor C1. Here, since the strength of the residual magnetism of the shadow mask is determined according to the magnitude of the positive and negative peak currents of the degaussing current, the amount of adjustment of the narrowing or widening of the irradiation surface of the electron beam depends on the magnitude of this residual magnetism. Decided. Therefore, it is possible to adjust the irradiation position of the electron beam by changing the positive / negative peak current of the degaussing current with the variable capacitor C1. In this sense
The variable capacitor C1 constitutes a variable circuit according to the present invention with a simple circuit.

Next, the operation of the degaussing apparatus according to this embodiment when degaussing the shadow mask provided in the picture tube 30 will be described. When the irradiation surface of the cathode ray tube 30 of the electron beam has a narrowed characteristic, the degaussing coil 10 is wound in the direction in which the first peak current flows in the direction illustrated in FIG. When 31 has a widening characteristic, the degaussing coil 10 is wound in a direction in which the first peak current flows in the direction illustrated in FIG. When the user turns on the power of the picture tube device, the battery 40
Supplies power to the variable capacitor C1 via the resistor R1, and the variable capacitor C1 accumulates electric charges. Then, when the power is turned off, the variable capacitor C1 stores the accumulated electric charge in the degaussing coil 10 from the connecting portion 22 via the connector 21.
Supply to. Here, when the power is off, the variable capacitor C
Since 1 and the degaussing coil 10 form a resonance circuit, as shown in FIG. 5, the degaussing current flowing through the degaussing coil 10 has an AC voltage waveform of a short cycle of about 1 cycle starting from the time when the power is turned off. Becomes The degaussing current in FIG. 5 is shown in the direction in which the first peak current becomes positive.

Since this degaussing current is generated by discharging the charge accumulated in the variable capacitor C1, the second peak current value I2 of the degaussing current is smaller than the first peak current value I1 of the degaussing current. And the degaussing coil 1
When 0, magnetic fluxes corresponding to different peak currents of positive and negative are generated to degauss the shadow mask provided in the picture tube 30, so that magnetism remains in the shadow mask. In this case, since the maximum peak current flowing through the degaussing coil 10 is the first peak current, in the example shown in FIGS. 2 and 3, when the direction of the first peak current flowing through the degaussing coil 10 is clockwise. The electron beam irradiation surface 31 of the picture tube 30 becomes a narrowed portion. When the direction of the first peak current flowing through the degaussing coil 10 is counterclockwise, the picture tube 3
The irradiation surface 31 of the electron beam of 0 is a spread. Therefore, in the picture tube device in which the electron beam irradiation surface 31 of the picture tube 30 has a narrowed characteristic, the degaussing coil 10 is wound in advance in the direction in which the first peak current flows in the direction illustrated in FIG. . On the other hand, in the picture tube device in which the irradiation surface 31 has the characteristic of widening, the degaussing coil 10 is wound in advance in the direction in which the first peak current flows in the direction illustrated in FIG.

For example, the picture tube device has a narrowed irradiation surface 3
1 has a degaussing current of one cycle generated by the degaussing current generating circuit 20, the peak current of the first time is in the direction in which the irradiation surface 31 is widened, and is in the opposite direction.
The peak current for the second time narrows the irradiation surface 31 and tends to turn the irradiation surface 31 toward the eyes. Here, since the peak current of the first time is larger than the peak current of the second time, after the degaussing current of one cycle flows through the degaussing coil 10, the residual magnetism that causes the irradiation surface 31 to spread to the shadow mask is increased. Will occur.
Then, the irradiation surface 31 of the electron beam changes in accordance with the residual magnetism that causes the spread eyes to correct the narrowed irradiation surface 31 of the picture tube device itself in the direction of the spread eyes. As a result, the deviation of the electron beam irradiation position due to the characteristics of the picture tube device is reduced.

In addition, the picture tube device has a spread irradiation surface 31.
, The first peak current of the degaussing current tends to narrow the irradiation surface 31. Then, after one cycle of the degaussing current flows through the degaussing coil 10, a residual magnetism that causes the irradiation surface 31 to be narrowed is generated in the shadow mask. In this case, the spread of the picture tube device itself is increased. The irradiation surface 31 is narrowed and corrected in the direction of the eyes. As a result, even when the picture tube device has the spread irradiation surface 31, the deviation of the electron beam irradiation position due to the characteristics of the picture tube device is reduced.

As described above, in the degaussing device of this embodiment, a degaussing current is passed through the degaussing coil 10 so as to correct the irradiation surface 31 of the narrowed or widened area due to the characteristics of the picture tube device itself. 31 can be made suitable width. Therefore, the CRT device is less displacement of the irradiation position of the electron beam of a picture tube according to characteristics of itself, it is possible to prevent deterioration or the like of the purity and
Both of them adjust the electron beam irradiation position with a simple circuit.
It is possible to provide a degaussing device and a degaussing method capable of performing degaussing.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a main configuration of a degaussing device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an irradiation surface of an electron beam when a peak current flows through a degaussing coil.

FIG. 3 is a schematic diagram showing an irradiation surface of an electron beam when a peak current flows in a direction opposite to that of FIG.

FIG. 4 is a circuit diagram showing a main configuration of a degaussing device according to a modification.

FIG. 5 is a waveform diagram showing an example of a degaussing current.

[Explanation of symbols]

10 ... Degaussing coil 20 ... Degaussing current generation circuit 21 ... Connector 22 ... Connection part 30 ... Picture tube 31 ... Irradiation surface 40 ... Battery 41 ... Power line R1 ... resistance C1 ... Variable capacitor 71 ... Changeover switch

Claims (3)

(57) [Claims] 1. One end is connected to a power supply line of a DC power supply.
The current limiting resistor and the other end of this resistor and ground
Variable capacitor connected between, same resistance and same variable
The connection part of the capacitor and the ground were connected to the input side
Connector and has the above power line when the power is turned on.
The charge is stored in the variable capacitor through the resistor.
The degaussing current generation circuit that generates a degaussing current that is a short-cycle AC voltage waveform by using the discharge of the variable capacitor when the power is off, and a degaussing current generation circuit that is attached to the picture tube and has both ends connected to the output side of the connector
It is is supplied to the degaussing current, the same picture tube
A degaussing coil wound in a direction to reduce the tendency of narrowing or widening of the irradiation surface of the electron beam.
However , the degaussing current generator circuit is stored in the variable capacitor.
Degaussing the generated charge via the connector when the power is turned off
Positive and negative peaks when power is off by supplying to coil
A degaussing device that generates the degaussing current with a variable current . 2. The degaussing device according to claim 1, wherein the connector is mounted on the output side with respect to the input side.
A degaussing device, which is a detachable connector with a variable direction . 3. One end is connected to a power supply line of a DC power supply.
The current limiting resistor and the other end of this resistor and ground
Variable capacitor connected between, same resistance and same variable
The connection part of the capacitor and the ground were connected to the input side
Connector and has the above power line when the power is turned on.
The charge is stored in the variable capacitor through the resistor.
However, when the power is turned off, the discharge of the variable capacitor is used to
Degaussing that produces a degaussing current that is the alternating voltage waveform of a cycle
Attached to the current generation circuit and the picture tube, both ends connected to the output side of the above connector
Is supplied with the above degaussing current, and
The tendency of narrowing or widening of the electron beam irradiation surface
By the degaussing coil wound in the direction to reduce the
Degaussing the shadow mask on the picture tube
This is a degaussing method in which the charge accumulated in the variable capacitor is
By supplying the degaussing coil through the connector
Degaussing with a positive and negative peak current variable when the power is turned off
Generate a current to degauss the shadow mask
Degaussing how to, characterized in that.