JP2002056789A - Deflecting yoke and display equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct simply a vertical unsymmetrical image distortion. SOLUTION: The deflecting yoke is constituted with an image distortion correction coil 19 which forms a correction magnetic field along horizontal axis direction prepared in a back edge side of the deflecting yoke, a 1st bridge circuit 20, and a 2nd bridge circuit 21 which adjusts direction and quantity of the correction current which flows in the image distortion correction coil 19. The 1st bridge circuit 20 transforms a perpendicular deflecting current Ih of saw-tooth-like waves given to a pair of a horizontal deflecting coils 16 into parabola-like correction current, and supplies the correction current to the image distortion correction coil 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cathode ray tube (CR)
The present invention relates to a display device such as a television receiver or a computer display using T), and in particular, to a deflection yoke (Deflection Yoke;
DY).

[0002]

2. Description of the Related Art Generally, a display device using a cathode ray tube is:
A deflection yoke deflects the electron beam emitted from the electron gun up, down, left, and right. The deflection yoke has a horizontal deflection coil and a vertical deflection coil, and is used by being mounted on a cathode ray tube. The horizontal deflection coil forms a horizontal deflection magnetic field that deflects the electron beam left and right (horizontal direction), and the vertical deflection coil shifts the electron beam up and down (vertical direction).
A vertical deflection magnetic field is formed to deflect the light into a vertical direction.

[0003] By the way, the manufacturing process of this type of display device includes a process of incorporating an electron gun into a neck portion of a cathode ray tube and a process of attaching a deflection yoke to a cone portion extending from the neck portion of the cathode ray tube to a funnel portion. . In the process of attaching components to each other, an attachment error occurs due to various factors, which may cause raster distortion on the screen of the display device.

One of the problems is that when the positions of the cathode ray tube, the deflection yoke, and the electron gun are shifted from each other in the vertical direction (vertical axis direction), the raster is distorted asymmetrically on the upper and lower sides of the screen (hereinafter, referred to as "the following"). (Referred to as “vertical asymmetric image distortion”). As a specific form of raster distortion generation, there are a case where the upper side of the screen is distorted in a barrel shape and the lower side is distorted in a barrel shape, and a case where the upper side of the screen is distorted in a barrel shape and the lower side is distorted in a pin cushion shape.

Therefore, conventionally, the vertical asymmetric image distortion is corrected by moving the deflection yoke up and down so as to be slightly inclined with respect to the central axis (tube axis) of the cathode ray tube.

[0006]

However, the operation of moving the deflection yoke up and down is performed manually, and the deflection yoke is finely moved to adjust the position. Therefore, the deflection yoke is fixed at an optimum position. It was difficult.
Further, since the vertically asymmetric image distortion varies from display device to display device (one unit), it is necessary to change the manner in which the deflection yoke is moved each time, and it takes time until the position adjustment is completed. Also, because the deflection yoke is moved up and down,
After the position adjustment, the deflection yoke had to be fixed to the cathode ray tube with a spacer such as a rubber wedge.

An object of the present invention is to provide a deflection yoke and a display device capable of easily correcting vertical asymmetric image distortion. .

[0008]

In the deflection yoke according to the present invention, an image distortion correction coil which is provided at a rear end side of the deflection yoke and forms a correction magnetic field along the horizontal axis direction; On the other hand, a current supply unit for supplying a parabolic correction current having a horizontal deflection period and a current adjustment unit for adjusting the amount and direction of the correction current flowing through the image distortion correction coil are provided. Further, in the display device according to the present invention, the deflection yoke having the above configuration is used.

In the deflection yoke having the above structure and the display device using the same, a parabolic correction current having a horizontal deflection period supplied from the current supply means is supplied to the image distortion correction coil to thereby provide a rear end of the deflection yoke. A correction magnetic field is formed along the horizontal axis. With this correction magnetic field, the electron beam is uniformly deflected upward or downward in the horizontal deflection cycle. At this time, when the electron beam is deflected upward, raster distortion occurs in a barrel shape on the upper side and a pincushion shape on the lower side on the screen, and when the electron beam is deflected downward,
On the screen, a raster distortion occurs in a pincushion shape on the upper side and a barrel shape on the lower side. Further, by adjusting the amount and direction of the correction current flowing through the image distortion correction coil by the current adjusting means, the deflection direction and the deflection amount of the electron beam by the correction magnetic field of the correction coil also change. Therefore, by adjusting the amount and direction of the correction current according to the form of the vertical asymmetric image distortion to be corrected, the vertical asymmetric image distortion can be corrected.

[0010]

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

FIG. 1 is a schematic perspective view showing an overall image of a cathode ray tube to which the present invention is applied. In FIG. 1, a cathode ray tube bulb (cathode ray tube main body) 10 includes a panel section 11, a funnel section 12, and a neck section 13. A fluorescent screen (not shown) in which blue, green, and red color phosphors are arranged in a pattern is formed on the inner surface of the panel unit 11. on the other hand,
An in-line type electron gun 14 serving as an emission source of an electron beam is provided in the neck portion 13. In addition, neck part 1
A deflection yoke 15 for deflecting the electron beam is mounted on a cone portion extending from 3 to the funnel portion 12.
The deflection yoke 15 is mounted and adjusted so that the center axis of the yoke coincides with the center axis of the cathode ray tube bulb 10.

The cathode ray tube having the above-described structure is incorporated in a casing (not shown) together with various accessories necessary for reproducing a color image (or a black and white image) on the phosphor screen on the inner surface of the panel section 11, thereby providing a television. A display device such as a receiver or a display for a computer is configured.

2A and 2B show a configuration of a deflection yoke according to an embodiment of the present invention, wherein FIG. 2A is a schematic side view thereof, and FIG.
FIG. 3 is a front view when viewed from the electron gun side. As shown, the deflection yoke 15 is provided with a horizontal deflection coil 16, a vertical deflection coil 17, and a DY core 18. The horizontal deflection coil 16 is wound in a saddle shape, and the vertical deflection coil 18 is also wound in a saddle shape. The vertical deflection coil 17 may be wound around the DY core 18 in a toroidal shape.

The saddle-shaped horizontal deflection coils 16 are arranged in pairs above and below (vertically) the deflection yoke 15, and the saddle-shaped vertical deflection coils 17 are positioned in pairs left and right (horizontally) of the deflection yoke 15. It is arranged. Then, on the trajectory of the three electron beams emitted in an in-line arrangement from the electron gun 14, the horizontal deflection coil 16 forms a magnetic field (horizontal deflection magnetic field) for deflecting the electron beam in the horizontal direction (horizontal direction) of the screen. The vertical deflection coil 17 forms a magnetic field (vertical deflection magnetic field) that deflects the electron beam in the vertical direction (vertical direction) of the screen.

The DY core 18 is made of a magnetic material such as ferrite and has a cylindrical structure with one opening in the direction of the yoke center axis (Z axis) larger than the other. This DY
The core 18 includes the horizontal deflection coil 16 and the vertical deflection coil 1.
In order to further enhance the effectiveness of the magnetic field generated by the, the deflecting coils 16 and 17 are mounted so as to cover them.

Further, an image distortion correction coil 19 is provided on the rear end side of the deflection yoke 15. The image distortion correction coil 19 includes a pair of correction coils L9 and L10. The pair of correction coils L9 and L10 are arranged in pairs in the X-axis direction that is the horizontal axis of the deflection yoke 15 so as to sandwich the neck portion 13 of the cathode ray tube from both sides (left and right). Further, each correction coil L9, L1
0 is wound on a winding bobbin (not shown) in a substantially rectangular shape in a side view along the outer peripheral surface of the neck portion 13, thereby forming an air-core coil. However, the correction coil L9,
L10 is not limited to the air core coil described above, and may be a coil wound using a core.

FIG. 3 is a circuit diagram showing a coil connection state according to the embodiment of the present invention, and FIG. 4 is a schematic diagram thereof. First, in FIG. 3, a pair of horizontal deflection coils 16 are connected in parallel with each other. A pair of horizontal deflection coils 16 are supplied with a sawtooth current having a horizontal deflection period, that is, a horizontal deflection current Ih by a horizontal deflection circuit (not shown). Further, a first bridge circuit 20 formed by connecting the four coils L1, L2, L3, and L4 in a bridge shape is connected in series to the pair of horizontal deflection coils 16. The first bridge circuit 20 corresponds to a correction current generation circuit according to the present invention.

In the first bridge circuit 20, 2
Two coils L1 and L2 are connected in series with a common connection point T1, and the other two coils L3 and L4 are also connected in series with a common connection point T2. The two coils L1 and L2 connected in series and the two coils L3 and L4 connected in series are connected to a common connection point T.
3 and T4 are connected in parallel. Further, a magnetic bias is applied to the two coils L1 and L2 by a permanent magnet (not shown), and no magnetic bias is applied to the other two coils L3 and L4.

Between the connection points T1 and T2 in the first bridge circuit 20, four coils L5, L6, L
7, a second bridge circuit 21 formed by connecting L8 in a bridge shape is connected in series. In the second bridge circuit 21, two coils L5 and L6 are connected in series with a common connection point T5, and the other two coils L7 and L8 are connected in series with a common connection point T6. ing. Then, two coils L5 and L6 connected in series and two coils L7 and L
8 are connected in parallel with common connection points T7 and T8.

Further, a pair of correction coils L9 and L10 constituting the image distortion correction coil 19 are connected between the connection points T5 and T6 in the second bridge circuit 21.
The pair of correction coils L9 and L10 are connected to each other in series.

Here, as shown in FIG. 4, four coils L5, L6, L7,
Among the coils L8, the coils L6 and L7 are wound (eg, bifilar wound) on one end of a coil bobbin 22 having a hollow structure. Similarly, the coils L5 and L8 are stacked on the other end of the coil bobbin 22. It is wound. A screw core 2 made of ferrite is provided in the hollow portion of the coil bobbin 22.
3 is inserted. The screw core 23 is guided and supported in the hollow portion of the coil bobbin 22 so as to be movable in the central axis direction (the left-right direction in FIG. 4). On the other hand, a rotary knob 24 is provided at an intermediate portion of the coil bobbin 22 in the center axis direction. A screw hole (female screw) (not shown) is formed in the center of the rotary knob 24, and the screw core 23 is screwed into the screw hole. These coil bobbin 22, screw core 23, rotary knob 24 and four coils L
The current adjusting means of the present invention is constituted by the second bridge circuit 21 composed of 5, L6, L7, and L8.

Next, the operation of the deflection yoke having the above configuration will be described.

First, the horizontal deflection current (sawtooth current) Ih supplied to the pair of horizontal deflection coils 16 by a horizontal deflection circuit (not shown) becomes positive in the first half of the horizontal deflection cycle and negative in the second half, for example. The horizontal deflection current Ih flows between the connection points T3 and T4 of the first bridge circuit 20 via the horizontal deflection coil 16.

At this time, the horizontal deflection current Ih is a plus current, that is, in the first half of the horizontal deflection cycle, the current flows from the direction indicated by the solid arrow in FIG. 3 to the connection point T3.
Then, while the coils L1 and L4 generate a magnetic field in the same direction as the bias magnetic field generated by the permanent magnet (not shown), the coils L2 and L3 generate a magnetic field in the opposite direction to the bias magnetic field. In such a case, the coils L1, L
The magnetic field due to No. 4 increases because it is in the same direction as the bias magnetic field, and the magnetic field due to coils L2 and L3 decreases because it is in the opposite direction to the bias magnetic field. Therefore, the coils L1, L4
, The inductance of the coils L2 and L3 increases. As a result, the current flowing from the connection point T3 flows through the coil having the smaller inductance, so that the current flows through the coil L1 to the second bridge circuit 21 as indicated by the solid line arrow in FIG. 3, and further flows through the coil L4. Out of the connection point T4.

On the other hand, when the horizontal deflection current Ih is a negative current, that is, in the latter half of the horizontal deflection cycle,
A current flows into the connection point T4 from the direction indicated by the dashed arrow in FIG. Then, the coils L1 and L4 generate a magnetic field in the direction opposite to the bias magnetic field generated by the permanent magnet (not shown), while the coils L2 and L3 generate a magnetic field in the same direction as the bias magnetic field. In such a case, the coil L
The magnetic field generated by the coils L1 and L4 decreases because they are in the opposite direction to the bias magnetic field, and the magnetic field generated by the coils L2 and L3 increases because they are in the same direction as the bias magnetic field. Therefore, the coil L
The inductance of the coils L2 and L3 increases.
Is reduced. Thereby, the connection point T4
3 flows through the coil having the smaller inductance as in the previous case, and therefore flows through the coil L2 as indicated by the broken line arrow in FIG.
1 and flows out of the connection point T3 via the coil L3.

As described above, even if the horizontal deflection current Ih supplied to the pair of horizontal deflection coils 16 changes to plus and minus in the first half and the second half of the horizontal deflection cycle, the second bridge circuit 21 has the same direction. Current flows. Thus, the first bridge circuit 20 causes the second bridge circuit 2
5 is a parabolic waveform synchronized with the horizontal deflection period 1H as shown in FIG. 5, and the parabolic current of the horizontal deflection period 1H is used to correct the image distortion in the second bridge circuit 21. It is supplied to the coil 19 (L9, L10).

On the other hand, in FIG.
2, each coil L6, L7 and L5, L wound on both sides
When the insertion lengths of the screw cores 23 with respect to each other are equal to each other, the inductances of the respective L6, L7 and L5, L8 are also equal to each other. In this state, the second bridge circuit 21
Is in a balanced state (balanced state).
9. No correction current flows through L10.

On the other hand, when the rotary knob 24 is rotated from the above state, the screw core 23 moves according to the direction and amount of rotation. Thereby, the coil bobbin 2
2, the insertion length of the screw core 23 relative to each of the coils L6, L7, L5, and L8 changes relatively, and accordingly, the inductance of each of the coils L6, L7, L5, and L8 changes differentially. That is, as the inductance of the coils L6 and L7 increases, the coil L6
5, the inductance of the coils L6 and L7 decreases, and conversely, the inductance of the coils L5 and L8 increases accordingly.

As described above, each of the coils L6, L7 and L5
When the inductance of L8 changes, the balance of the second bridge circuit 21 is lost and the image distortion correction coil 19 (L
9, L10), the amount and direction of the correction current flowing through the image distortion correction coil 19 (L9, L10) change according to the change in the inductance. That is, when the inductances of the coils L6 and L7 are larger than the inductances of the coils L5 and L8, the correction current I1 flows from the connection point T6 toward T5, and the inductances of the coils L5 and L8 are reduced.
If the inductance is larger than L7, the connection point T5
From T6 to T6. Further, the amounts of the correction currents I1 and I2 increase as the difference between the inductances L6, L7 and L5, L8 increases.

Here, the image distortion correction coil 19 (L9, L
When the correction current I1 flows in 10), as shown in FIG. 4, one correction coil L is placed on the trajectory of the three electron beams B, G, and R traveling in the neck portion 13 in an in-line arrangement.
A correction magnetic field φV is formed with 9 as the N pole and the other correction coil L10 as the S pole. This correction magnetic field φV is a magnetic field along the horizontal axis direction (X-axis direction in FIG. 2) of the deflection yoke. Therefore, the three electron beams B, G, and R are uniformly deflected upward in the horizontal deflection cycle.

Incidentally, the correction magnetic field formed by the image distortion correction coil 19 is not limited to the pincushion-type magnetic field as shown in the figure, but may be a barrel-type magnetic field or a uniform magnetic field.

As described above, the three electron beams B, G, R
Is deflected upward, the positional relationship between the vertical deflection magnetic field formed by the vertical deflection coil 17 and the electron beams B, G, and R passing through the vertical deflection magnetic field changes. Thus, when the parabolic wave correction current shown in FIG. 5 is clamped at the average value, the electron beam moves uniformly to the upper side of the screen during the horizontal scanning of the center of the screen, and the left and right sides of the screen are horizontally moved. During the scanning period, the electron beam moves uniformly to the lower side of the screen.

Therefore, as shown in FIG. 6, for example, a vertically asymmetric raster 2 having a pincushion shape on the upper side and a barrel shape on the lower side of the screen 1 (vertical asymmetric image distortion).
Has occurred, the correction coil 19 (L
9, L10). As a result, the raster 2 is displaced upward in the center of the screen 1 and the raster 2 is displaced downward on the left and right sides of the screen 1. Therefore, the amount of the correction current I1 is appropriately adjusted by turning the rotary knob 24 described above. By doing so, it is possible to appropriately correct the vertically asymmetric image distortion shown in FIG.

Although not shown, if a vertically asymmetric raster distortion (vertical asymmetric image distortion) in which the upper side has a barrel shape and the lower side has a pincushion shape on the screen 1 (vertical asymmetric image distortion), the correction coil 19 (L9 , L10), and by appropriately adjusting the amount of the correction current I2, it is possible to appropriately correct the vertically asymmetric image distortion as described above.

As described above, in the present embodiment, by rotating the rotary knob 24 to move the screw core 23, the electron beam is deflected upward or downward by the correction magnetic field of the image distortion correction coil 21, so that the image is vertically asymmetric. The distortion can be easily corrected. In addition, rotary knob 2
4 can also be easily performed, so that the image quality can be improved by increasing the correction accuracy of the vertically asymmetric image distortion.

Further, in correcting the vertically asymmetric image distortion, it is not necessary to move the deflection yoke up and down mechanically. Therefore, the labor required for adjusting the position of the deflection yoke can be saved. Also, before correcting the vertical asymmetric image distortion, the deflection yoke is brought into contact with the cathode ray tube (to be in close contact with it).
Since it can be attached, the trouble of fixing the deflection yoke after the position adjustment as in the related art and the spacer used for fixing are unnecessary.

Incidentally, in correcting the vertical asymmetric image distortion, the correction can be performed in principle even if a direct current is supplied to the image distortion correction coil 19. However, in order to supply a DC current to the image distortion correction coil 19, it is necessary to newly provide a current supply source therefor, which is disadvantageous in cost. On the other hand, the circuit (first bridge circuit 20) for generating a parabolic correction current as described above is widely used in existing deflection yokes for applications such as convergence correction, so that a new current supply is required. There is no need to secure a source.

Further, when the parabolic correction current is clamped to the average value as shown in FIG. 5, the amplitude of one side can be suppressed to a small value. Can be.

Further, when a direct current is applied to the image distortion correction coil 19, the trajectory of the electron beam is vertically displaced up and down with respect to the central axis of the cathode ray tube. Of the deflection magnetic fields (vertical deflection magnetic field and horizontal deflection magnetic field) applied to the electron beams B and R of FIG.
As a result, as shown in FIGS.
Comparing before and after correcting the distortion, the convergence deviation amount in which the electron beams B and R on both sides cross each other on the X axis and the Y axis of the screen 1 greatly changes. Such a change in convergence also occurs when the deflection yoke is moved up and down mechanically. On the other hand, when a parabolic correction current is employed, the moving distance Ly of the electron beam in the vertical direction (see FIG. 8)
Therefore, the influence on the convergence can be extremely reduced.

[0040]

As described above, according to the present invention, the current supply means supplies a parabolic correction current having a horizontal deflection period to the correction coil, and the amount and direction of the correction current flowing through the correction coil. Is adjusted by the current adjusting means, the vertically asymmetric image distortion generated on the screen can be easily corrected by the correction magnetic field of the correction coil. This eliminates the need to mechanically adjust the vertical position of the deflection yoke, so that it is possible to simultaneously improve the assemblability of the display device and the quality of the displayed image.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an overall image of a cathode ray tube to which the present invention is applied.

FIG. 2 is a diagram showing a configuration of a deflection yoke according to the embodiment of the present invention.

FIG. 3 is a circuit diagram showing a coil connection state according to the embodiment of the present invention.

FIG. 4 is a schematic diagram showing a coil connection state according to the embodiment of the present invention.

FIG. 5 is a waveform diagram of a correction current generated by a correction current generation circuit (first bridge circuit).

FIG. 6 is a diagram illustrating a change in raster due to a correction magnetic field of an image distortion correction coil.

FIG. 7 is a diagram illustrating a change in convergence caused by image distortion correction.

FIG. 8 is a schematic side view showing a change in the trajectory of an electron beam.

DESCRIPTION OF SYMBOLS 10: cathode ray tube bulb, 15: deflection yoke, 16: horizontal deflection coil, 17: vertical deflection coil, 19: image distortion correction coil, L1 to L8: coil, L9, L10: correction coil, 20 ... 1st bridge circuit, 21 ... second bridge circuit, 22 ... coil bobbin, 23 ... screw core, 24 ... rotary knob

Claims (3)

[Claims] 1. An image distortion correction coil provided at a rear end side of a deflection yoke to form a correction magnetic field along a horizontal axis direction, and a parabolic correction current having a horizontal deflection period is supplied to the image distortion correction coil. A deflection yoke, comprising: a current supply unit that adjusts an amount and a direction of the correction current flowing through the image distortion correction coil. 2. The current supply means is connected in series to a pair of horizontal deflection coils, and corrects the parabolic correction of the sawtooth current of a horizontal deflection cycle supplied to the pair of horizontal deflection coils. 2. The deflection yoke according to claim 1, further comprising a correction current generation circuit that converts the current into a current. 3. An image distortion correction coil provided on the rear end side of the deflection yoke to form a correction magnetic field along a horizontal axis direction, and a current for supplying a parabolic correction current having a horizontal deflection period to the image distortion correction coil. A display device using a deflection yoke comprising: a supply unit; and a current adjusting unit that adjusts an amount and a direction of the correction current flowing through the image distortion correction coil.