JP3434531B2 - Demagnetization method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to degaussing <br/> how of the color picture tube.

[0002]

2. Description of the Related Art Generally, in a color picture tube, various tube internal members made of a magnetic material are arranged in the tube. Therefore, if the tube inner member made of these magnetic materials is magnetized undesirably,
Due to the magnetic field generated by the magnetization, the trajectory of the electron beam emitted from the electron gun is deviated, which causes color misregistration on the screen. Therefore, it is necessary for the color picture tube to degauss its undesired magnetization at the time of characteristic inspection after manufacturing or when it is incorporated in a receiver.

As a degaussing method thereof, Japanese Utility Model Laid-Open No. 54-153
As shown in FIGS. 4 and 5, Japanese Patent No. 536 discloses a degaussing coil including a first ring-shaped coil 1 and a first ring-shaped coil 1.
1 is divided into three ring-shaped coils 1, 2a, 2b intersecting each other, which are composed of a pair of second ring-shaped coils 2a, 2b, and the first ring-shaped coil 1 is arranged in front of the color picture tube 3;
The second ring-shaped coils 2a and 2b are arranged on the left and right (x-axis direction) or up-and-down (y-axis direction) side surfaces of the color picture tube 3, and the ring-shaped coils 1, 2a and 2b generate an AC magnetic field to demagnetize. It shows how to do it.

In this method, a magnetic field Hz in the tube axis (z-axis) direction is generated by the first ring-shaped coil 1 arranged on the front surface of the color picture tube, and the second ring-shaped coils 2a and 2b are arranged on the left and right. (In the case of FIG. 4), the magnetic field Hx in the horizontal (x-axis) direction, and in the case where the second annular coils 2a and 2b are arranged above and below (in the case of FIG. 5), the vertical (y-axis) direction. Magnetic field Hy is generated, and demagnetization in two directions is performed at the same time.

However, in this case, arrows 4a, 4b, and
As shown by 5a and 5b, a reverse current flows, and the magnetic field generated by the one annular coil 2a and the magnetic field generated by the other annular coil 2b are in opposite directions. Therefore, the repulsion of the magnetic field generated by each ring-shaped coil 2a, 2b becomes stronger from the left, right, or upper and lower peripheral parts of the front surface of the color picture tube 3 toward the center, and in the center part, the second ring-shaped coil 2a, 2b. The horizontal or vertical magnetic fields Hx and Hy of
There is a problem that the desired degaussing effect cannot be obtained.

[0006]

As described above, as a method of degaussing various in-tube members made of a magnetic material and arranged in the tube of a color picture tube, conventionally, a first ring-shaped coil is provided on the front surface of the color picture tube. There is a method in which a pair of second ring-shaped coils obtained by branching the first ring-shaped coil are arranged so as to intersect each other on the left and right or top and bottom, and an alternating magnetic field is generated by each of these ring-shaped coils to demagnetize. . According to this method, in addition to the magnetic field Hz in the tube axial direction generated by the first annular coil arranged in front of the color picture tube, the second coil
The horizontal magnetic field Hx is generated when the ring-shaped coils are arranged left and right, and the vertical magnetic field Hy is generated when the second ring-shaped coils are arranged vertically.

In this case, however, reverse currents flow in the second ring-shaped coils arranged on the left and right or on the upper and lower sides,
The magnetic field generated by one ring-shaped coil and the magnetic field generated by the other ring-shaped coil are in opposite directions. Therefore, the repulsion of the magnetic field generated by each ring-shaped coil becomes stronger as it goes from the left and right or the upper and lower peripheral parts of the front surface of the color picture tube to the center,
In the central portion, there is a problem that the horizontal or vertical magnetic fields Hx and Hy of the second annular coil are not generated, and the desired degaussing effect cannot be obtained.

The present invention has been made to solve the above problems, and when a plurality of ring-shaped coils are arranged around the front surface of a color picture tube for demagnetization, mutual interference of the ring-shaped coils is eliminated. Te, and an object thereof is to make improve the demagnetization effect.

[0009]

In a degaussing method for a color picture tube, a first ring-shaped coil is arranged in front of the color picture tube, and a current for generating a degaussing magnetic field is passed through the first ring-shaped coil to perform a degaussing operation. How to make it, the left and right of the color picture tube,
One set of second ring-shaped coils is arranged on either one of the upper and lower sides, or one set of second and third ring-shaped coils is arranged on each of the left, right, upper and lower sides, and this one set of second ring-shaped coil is arranged. Or a method of degaussing by passing a current that generates a demagnetizing magnetic field in the same direction through each pair of second and third ring-shaped coils, and the first and second ring-shaped coils or the first and second ring-shaped coils. , The third ring-shaped coil is operated in different time zones, or the second and third ring-shaped coils are respectively set to the first
It was made to operate at the same time as the ring-shaped coil.

[0010]

[0011]

As described above, the first ring-shaped coil is arranged on the front surface of the color picture tube, and apart from this first ring-shaped coil, one set of the second ring is arranged on either the left, right, or top of the color picture tube. Or a pair of second and third ring-shaped coils arranged on each of the left and right sides and the upper and lower sides of the ring-shaped coil, and a current for generating a demagnetizing magnetic field in the same direction is applied to each set of the ring-shaped coils, and ,
The second ring-shaped coil or the first, second, and third ring-shaped coils are operated in different time zones, or the second,
If the third ring-shaped coils are simultaneously operated in different time zones from the first ring-shaped coil, mutual interference of magnetic fields generated by the respective ring-shaped coils can be eliminated or reduced,
The degaussing effect can be improved.

[0012]

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

Example 1. As shown in FIG. 1, the degaussing device of this example includes a first ring-shaped coil 10 arranged on the front surface of the color picture tube 3 and a pair of first coil arranged on the left and right side surfaces of the front surface of the color picture tube 3. It has two ring-shaped coils 11L and 11R. These first and second ring-shaped coils 10, 11L, 11
Each R is connected to a power source (not shown), especially the second
Each of the ring-shaped coils 11L and 11R is configured so that the alternating current ix in the same direction flows as shown by an arrow 12.

In the degaussing method using this degaussing device, for example, a current iz is first applied to the first ring-shaped coil 10 for a certain period of time,
After turning off the first ring-shaped coil 10, a current ix in the same direction is passed through the second ring-shaped coils 11L and 11R for a certain period of time, or the first ring-shaped coil 10 and the second ring-shaped coil 11 are fed.
Currents iz and ix are alternately applied to L and 11R. In either case, generally, the currents iz and ix to be passed are gradually reduced to gradually attenuate the generated magnetic field.

In this case, like the conventional degaussing method, the first
If currents are simultaneously applied to the second ring-shaped coils 10, 11L and 11R, for example, as shown in FIG. 1, a current iz in the direction of arrow 14 is applied to the first ring-shaped coil 10 and the second ring-shaped coil 10 is supplied. Assuming that a current ix in the direction of arrow 12 is applied to 11L and 11R, on the left side of the front of the color picture tube 3, the first
Current iz flowing through the ring-shaped coil 10 and the second ring-shaped coil 11
The current ix flowing through L is in the opposite direction, and the magnetic field generated by these ring-shaped coils 10 and 11L repels, so that the degaussing magnetic field decreases on the left side. On the other hand, on the right side, the current iz flowing through the first ring-shaped coil 10 and the current ix flowing through the second ring-shaped coil 11R have the same direction, and these ring-shaped coils
Due to the increase in the magnetic field generated by 10 and 11R, the demagnetizing field increases on the right side, and it is not possible to obtain a uniform demagnetizing field on the left and right.

However, as described above, when the currents iz and ix are flown to the first ring-shaped coil 10 and the second ring-shaped coils 11L and 11R so that they do not overlap with each other by shifting the time zones, the above-mentioned current flows simultaneously. It is possible to avoid the interference of magnetic fields such as.

Since the currents ix in the same direction are passed through the second ring-shaped coils 11L and 11R, these ring-shaped coils 11L and 11R
Generate a magnetic field Hx in the same direction. Therefore, unlike the conventional case, the repulsion of the magnetic field generated by both annular coils becomes stronger from the peripheral portion of the front surface toward the center, and the undesired phenomenon that the magnetic field Hx is not generated at the center is eliminated. As a result, a uniform demagnetizing magnetic field can be obtained.

Further, since the ring-shaped coils 10, 11L and 11R are arranged independently, each ring-shaped coil 10, 11L,
11R can be formed in a desired shape, and a uniform magnetic field can be easily obtained.

Example 2. As shown in FIG. 2, the degaussing device of this example includes a first ring-shaped coil 10 arranged on the front surface of the color picture tube 3 and a pair of second coil arranged above and below the front surface of the color picture tube 3. It has an annular coil 11T and 11B.
These first and second ring-shaped coils 10, 11T, 11B are respectively connected to a power source (not shown), and in particular, the second ring-shaped coils 11T, 11B are supplied with an alternating current iy in the same direction as indicated by an arrow 16. It is designed to flow.

In the degaussing method using this degaussing device, for example, first, a current iz is applied to the first annular coil 10 for a certain period of time,
After turning off the first ring-shaped coil 10, a current iy in the same direction is applied to the second ring-shaped coils 11T and 11B for a certain period of time, or the first ring-shaped coil 10 and the second ring-shaped coil 11 are fed.
Currents iz and iy are alternately applied to T and 11B. In either case, generally, the currents iz and iy flowing are gradually reduced to gradually attenuate the generated magnetic field.

Also in this case, if currents are simultaneously applied to the first and second ring-shaped coils 10, 11T and 11B as in the conventional degaussing method, for example, as shown in FIG.
Assuming that the current iz in the direction of arrow 14 is passed through the ring-shaped coil 10 and the current iy in the direction of arrow 16 is passed through the second ring-shaped coils 11T and 11B, when viewed from the front of the color picture tube 3, the first coil is Current iz flowing in the ring-shaped coil 10 and the second ring-shaped coil
The current iy flowing in 11B is in the opposite direction, and due to the repulsion of the magnetic field generated by these annular coils 10 and 11B,
The degaussing field is reduced. On the other hand, on the upper side, the current iz flowing through the first annular coil 10 and the second annular coil 11T
The current iy flowing in the same direction has the same direction, and the demagnetizing magnetic field increases on the upper side due to the increase of the magnetic field generated by these ring-shaped coils 10 and 11T.

However, as described above, when the currents iz and iy are made to flow to the first ring-shaped coil 10 and the second ring-shaped coils 11T and 11B so that they do not overlap each other by shifting the time zones, the case where the currents simultaneously flow It is possible to avoid the interference of magnetic fields such as.

Further, since the currents iy in the same direction are passed through the second ring-shaped coils 11T and 11B, these ring-shaped coils 11T and 11B are
Generate a magnetic field Hy of the same direction. Therefore, unlike the conventional case, the repulsion of the magnetic field generated by both annular coils becomes stronger from the peripheral portion of the front surface toward the center, and the undesired phenomenon that the magnetic field Hx is not generated at the center is eliminated. As a result, even in this case, a uniform demagnetizing magnetic field can be obtained.

Further, since the ring-shaped coils 10, 11T and 11B are arranged independently, each ring-shaped coil 10, 11T,
11B can be formed into a desired shape, and a uniform magnetic field can be easily obtained.

Example 3. As shown in FIG. 3, the degaussing device of this example has a color picture tube.
The first ring-shaped coil 10 arranged on the front surface of the CRT 3, the pair of second ring-shaped coils 11L and 11R arranged on the left and right side surfaces of the front surface of the color picture tube 3, and the pair arranged on the upper and lower side surfaces. And third ring-shaped coils 11T and 11B. These first,
Second and third ring-shaped coils 10, 11L, 11R, 11T, 11B
Are connected to a power source (not shown), and in particular , the arrow 1
As shown in 2 and 16, alternating current i in the same direction
It is configured so that x and iy flow.

In the degaussing method using this degaussing device, for example, a current iz is first applied to the first ring-shaped coil 10 for a certain period of time,
After turning off the first ring-shaped coil 10, a current ix in the same direction is applied to the second ring-shaped coils 11L and 11R for a certain period of time,
After turning off the second ring-shaped coils 11L and 11R, a current iy in the same direction is applied to the third ring-shaped coils 11T and 11B for a certain period of time.
Or the currents iz, ix, iy are sequentially and alternately applied to the first ring-shaped coil 10, the second ring-shaped coils 11L and 11R, and the third ring-shaped coils 11T and 11B. The currents iz, ix, iy are gradually reduced,
This is done by gradually attenuating the generated magnetic field.

As described above, the first, second and third annular coils
When the currents iz, ix and iy are supplied to 10, 11L, 11R, 11T and 11B so that they do not overlap each other by shifting the time zones, the ring-shaped coils 10, 11L, 11R and 11T are similar to the above embodiments.
, 11B generated magnetic fields Hz, Hx, and Hy can be prevented from interfering with each other.

The second and third annular coils 11L, 11R,
Since the electric currents ix and iy in the same direction flow in 11T and 11B, the annular coils 11L, 11R, 11T and 11B generate magnetic fields Hx and Hy in the same direction. Therefore, the repulsion of the magnetic field generated by the two annular coils becomes stronger as going from the peripheral portion of the front surface to the center as in the conventional case, and the undesired phenomenon that the magnetic fields Hx and Hy are not generated at the center disappears, and the uniform demagnetization magnetic field is eliminated. Will be obtained. Moreover, since the demagnetization is performed by the magnetic fields Hz, Hx, and Hy in the three directions, the demagnetization can be performed more effectively.

Further, each ring-shaped coil 10, 11L, 11R, 11T,
Since 11B is arranged independently, each of the ring-shaped coils 10, 11L, 11R, 11T, 11B can be formed in a desired shape, and a uniform magnetic field can be easily obtained.

In this degaussing device, as another degaussing method, for example, a current iz is first passed through the first ring-shaped coil 10 for a certain period of time to turn off the first ring-shaped coil 10, and then the second ring-shaped coil 10 is turned off. The currents ix in the same direction are applied to the coils 11L and 11R for a fixed time, and at the same time, the currents iy in the same direction are applied to the third ring-shaped coils 11T and 11B for a fixed time. 3 ring coils 11L, 11R, 11
Currents iz, ix, and iy are alternately applied to T and 11B,
In any case, the currents iz, ix, iy that flow are
May be gradually reduced so that the generated magnetic field is gradually attenuated.

In this way, the second and third ring-shaped coils 11L,
11R, 11T, and 11B have currents ix in the same direction at the same time,
Even if iy is flowed, the mutual interference between the magnetic fields Hx and Hy generated by the second ring-shaped coils 11L and 11R and the third ring-shaped coils 11T and 11B, which are arranged on the left and right, and above and below, is small, and the above first and
The second and third annular coils 10, 11L, 11R, 11T and 11B are shifted in time so that the currents iz and i do not overlap each other.
Almost the same effect as when flowing x and iy can be obtained.

[0033]

The first ring-shaped coil is arranged on the front surface of the color picture tube, and apart from the first ring-shaped coil, one set of the second ring-shaped coil is provided on either the left, right, or top of the color picture tube. Alternatively, one set of second and third ring-shaped coils is arranged on both the left and right sides and the upper and lower sides, and a current for generating a demagnetizing magnetic field in the same direction is passed through each of the one set of ring-shaped coils, and the first and second Or the first, second, and third annular coils are operated in different time zones, or the second and third annular coils are simultaneously operated in different time zones from the first annular coil, respectively. In this case, mutual interference of magnetic fields generated by the ring-shaped coils can be eliminated or reduced, and the degaussing effect can be improved.

[0034]

[Brief description of drawings]

FIG. 1 is a diagram for explaining a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a second embodiment of the present invention.

FIG. 3 is a diagram for explaining a third embodiment of the present invention.

FIG. 4 is a diagram for explaining an example of a conventional degaussing method.

FIG. 5 is a diagram for explaining another example of the conventional degaussing method.

[Explanation of symbols]

3 ... Color picture tube 10 ... First ring-shaped coils 11L, 11R ... One set of second ring-shaped coils 11T, 11B arranged on the left and right side faces ... One set of second ring-shaped coils or the first ring-shaped coils arranged on the upper and lower side faces 3 coils

Claims (2)

(57) [Claims] 1. A method of arranging a first ring-shaped coil on the front surface of a color picture tube and causing a current to generate a degaussing magnetic field in the first ring-shaped coil to perform a degaussing operation, and at least the left and right sides of the color picture tube. A pair of second ring-shaped coils is disposed on either the upper or lower side, and a current for generating a degaussing magnetic field in the same direction is passed through the pair of second ring-shaped coils to perform a degaussing operation. A degaussing method characterized in that the first and second ring-shaped coils are operated in different time zones. 2. A method of arranging a first ring-shaped coil on the front surface of a color picture tube and causing a current to generate a degaussing magnetic field in the first ring-shaped coil to perform a degaussing operation. And a pair of second and third ring-shaped coils are arranged in each of the two sets, and a current for generating a degaussing magnetic field in the same direction is passed through the pair of second and third ring-shaped coils to perform a degaussing operation. A degaussing method comprising operating the first annular coil and the second and third annular coils in different time zones.