JP2705535B2 - Cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube, and more particularly to a cathode ray tube incorporating a raster correction coil for correcting raster distortion.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 6, a cathode ray tube such as a color picture tube emits an electron beam L emitted from an electron gun 3 housed in a neck 2 of a cathode ray tube bulb 1 on the outer periphery of a funnel 4. The fluorescent film 7 formed on the inner surface of the face panel 6 while scanning by the mounted deflection yoke 5.
The structure is such that the electron beam L is accurately landed on the dot-shaped RGB phosphors constituting the phosphor film 8 on the inner surface of the face panel 6 via the shadow mask 8.

That is, the deflection yoke 5 has a horizontal deflection coil 9 for deflecting the electron beam L right and left and a vertical deflection coil 10 for deflecting the electron beam L up and down. 750 KHz, vertical deflection coil 1
0, a sawtooth current of about 60 Hz is caused to flow, and a predetermined electromagnetic deflection magnetic field is generated in the cathode ray tube bulb 1. As shown in FIG. Trajectory).

The raster 11 is provided on the deflection yoke 5.
Is the trajectory of the scanning line of the electron beam L deflected by
Distortion is affected by the performance of the deflection yoke 5 and the manner in which the deflection yoke 5 is attached, so that the peripheral part, both sides, and upper and lower surfaces of the raster 11 are not distorted and a normal image is obtained. There is a problem that there is no. In addition, there is a problem that the electron beam L is twisted right and left under the influence of geomagnetism and the like, and the landing position is shifted, and the four corners of the image are color-shifted.

Since the cathode ray tube bulb 1 is not a spherical surface centered on the deflection point of the electron beam L, the electron beam L
Vibrates greatly at the four corners around the valve, for example, as shown in FIG. 8, causing a vertical pincushion distortion 11a in which the vertical amplitude is insufficient at the center of the screen, or as shown in FIG. The right and left pincushion distortion 11b may be generated as the position becomes smaller.

For this reason, various countermeasures have been taken for the displacement of the landing position due to the upper and lower pincushion distortion 11a and the left and right pincushion distortion 11b of the raster 11 or the terrestrial magnetism.

For example, for the former pincushion distortion 11a, a horizontal period parabolic current is superimposed on the vertical deflection current, and for the latter left / right pincushion distortion 11b, the vertical deflection current is parabolically amplified. The correction is made by passing a current with an unbalanced waveform. Further, as shown in FIG. 10, the horizontal deflection magnetic field of the horizontal deflection coil 9 is formed in a pincushion shape.
As shown in FIG. 11, a method of forming a vertical deflection magnetic field of the vertical deflection coil 10 into a barrel shape to correct pincushion distortion of the raster 11 is also employed.

[0008] In addition, displacement of the landing position due to terrestrial magnetism, for example, as shown in FIG. 12, terrestrial magnetism B0 enters the outer peripheral surface of the face panel 6 of the cathode ray tube bulb 1 and acts on the electron beam L to cause the face panel 6 to move. To solve the problem of displacement at the four corners of the screen, the degaussing coil 12 may be wound around the outer peripheral end face of the face panel 6 or the deflection yoke 5
A demagnetizing coil 13 is mounted in the vicinity of the coil bobbin, and a direct current is applied to these degaussing coils 12 and 13 to apply a tube surface canceling magnetic field B1 to the outer peripheral surface of the face panel 6 to cancel geomagnetism. (Japanese Utility Model Laid-Open No. 3-37743).

[0009]

However, the cathode ray tube which has been subjected to the countermeasures against the pincushion distortion of the raster and the displacement of the landing position of the terrestrial magnetism as described above also has a problem in that the upper and lower amplitudes of the raster during the raster adjustment after the deflection yoke is mounted. A trapezoidal distortion that changes linearly or a parallelogram distortion in which the upper and lower ends of the raster are inclined parallel to each other may occur. The trapezoidal distortion and parallelogram distortion in which the upper and lower ends of the raster are linearly inclined are related to the way of attaching the deflection yoke, etc., but are basically related to the variation in the design and manufacturing of the deflection yoke. Was irrevocable. Therefore, the conventional cathode ray tube having a trapezoidal distortion or a parallelogram distortion of the raster has to be sorted out and a defective product must be discarded.

Therefore, the present invention has been made in view of the trapezoidal distortion and the parallelogram distortion of the raster generated in the cathode ray tube, and corrects the trapezoidal distortion and the parallelogram distortion in which the upper and lower ends of the raster are linearly inclined. It is an object of the present invention to provide a cathode ray tube which can be used.

[0011]

As a method of correcting the trapezoidal distortion and the parallelogram distortion of the raster, the present inventor has arranged the raster near the deflection yoke on the outer periphery of the funnel in the same manner as the countermeasure for the landing position deviation of the terrestrial magnetism. By passing a sawtooth wave current synchronized with the vertical deflection frequency through a substantially annular raster correction coil wound in a planar shape that is substantially perpendicular to the tube axis of the cathode ray tube bulb, a straight line is drawn in the vertical direction of the image of the cathode ray tube. A method of applying a correction magnetic field that corrects the raster distortion that has undergone the amplitude change was considered. In other words, the trapezoidal distortion and parallelogram distortion of the raster focus on the fact that the upper and lower ends of the raster are linearly inclined, and that the center of the raster screen is almost accurately landed by the electron beam. The correction magnetic field is formed so as to obtain a magnetic field that linearly increases or demagnetizes in the vertical direction, and the electron beam is scanned by superimposing the correction magnetic field on the scanning magnetic field of the deflection yoke. . That is, the cathode ray tube of the present invention scans the electron beam emitted from the electron gun housed in the neck of the cathode ray tube bulb by the deflection yoke mounted on the outer periphery of the funnel, and irradiates it on the fluorescent film formed on the inner surface of the face panel. In a cathode ray tube for forming a predetermined raster on the face panel, a sawtooth current synchronized with the vertical deflection frequency is applied to the vicinity of the deflection yoke on the outer periphery of the funnel to generate a vertical magnetic field for correcting raster distortion. It is characterized in that a raster correction coil is provided. Further, in the cathode ray tube of the present invention, the applied current is inclined in one direction with the middle point being zero in one vertical cycle with respect to a raster distortion formed in a trapezoidal shape in which the vertical amplitude changes linearly. It is characterized by being a sawtooth current. Further, in the cathode ray tube of the present invention, in response to raster distortion formed in a parallelogram shape in which the upper and lower ends are inclined in parallel with each other, the applied current bends with the midpoint being zero in one vertical cycle, and It is characterized by a sawtooth current that is inclined in the opposite direction from the point.

[0012]

A correction magnetic field for correcting a raster distortion by a raster correction coil is applied to the electron beam in addition to the scanning magnetic field by the deflection yoke.

Since a sawtooth current synchronized with the vertical deflection frequency is applied to the raster correction coil, a magnetic field that gradually increases or demagnetizes linearly in the vertical direction in accordance with the slope of the sawtooth current to the raster correction coil. A correction magnetic field is formed according to the amount of inclination of the raster distortion generated by the scanning magnetic field of the deflection yoke. In this case, when a sawtooth wave current that is inclined in one direction with the middle point being zero in one vertical cycle is applied to the raster correction coil, the correction magnetic field becomes a correction magnetic field in the opposite direction on the upper and lower sides of the raster, and the upper and lower amplitudes are linear. For a trapezoidal raster distortion that changes gradually, that is, a distortion in which the upper and lower ends are inclined in opposite directions, the inclination is corrected to be flat on the upper and lower sides. Also,
When the midpoint is inflected in one vertical cycle of the raster correction coil and a sawtooth current is inclined in the opposite direction from the midpoint, a correction magnetic field in the same direction is applied to the upper and lower sides of the raster, and the For parallelogram-shaped raster distortion whose edges are inclined parallel to each other, that is, for distortion whose upper and lower ends are inclined in the same direction,
Correct the inclination to be flat on the upper and lower sides.

Since the center point of the sawtooth current applied to the raster correction coil is set to zero, no correction magnetic field is applied to the center of the screen, and the electron beam in the center of the screen does not twist, The landing position does not shift. Further, since the correction magnetic field is proportional to the applied sawtooth current, it is possible to cope with the distortion of the raster image to be corrected by appropriately adjusting the peak value.

[0015]

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

FIG. 1 shows a cathode ray tube used for a color picture tube or the like of the present invention. Like the cathode ray tube of FIG. 6, an electron beam L emitted from an electron gun 3 housed in a neck 2 of a cathode ray tube bulb 1 is shown. Is irradiated onto the fluorescent film 7 formed on the inner surface of the face panel 6 while scanning by the deflection yoke 5 mounted on the outer periphery of the funnel 4. The deflection yoke 5 has a horizontal deflection coil 9 for deflecting the electron beam L right and left and a vertical deflection coil 10 for deflecting the electron beam L up and down.
A sawtooth current having a predetermined period is applied to the horizontal deflection coil 9 and the vertical deflection coil 10 to generate a scanning magnetic field of the electron beam L, and the four sides as shown in FIG. A raster 11 having a shape is formed.

This cathode ray tube differs from the conventional cathode ray tube in that a raster correction coil 14 for correcting raster distortion is arranged near the deflection yoke 5 to apply a sawtooth current synchronized with the vertical deflection frequency. , This correction coil 1
The only difference is that the magnetic field of No. 4 is superimposed on the scanning magnetic field of the deflection yoke 5 for scanning the electron beam L, and the trapezoidal distortion and the parallelogram distortion of the raster scanned by the deflection yoke 5 are corrected to a normal raster pattern. Other configurations are the same as those of the cathode ray tube of FIG. 6, and the same functional components are denoted by the same reference numerals as those of FIG. 6, and the description thereof is omitted.

FIG. 2 shows a trapezoidal distortion pattern 11a in which the raster 11 obtained by scanning the electron beam L with the deflection yoke 5 in the cathode ray tube has a trapezoidal shape whose upper and lower amplitudes change linearly. That is, the trapezoidal distortion 11a
As shown in the figure, has a trapezoidal shape in which the upper end is inclined downward to the right and the lower end is inclined upward to the right. The amplitude value on the right side gradually decreases, and the amplitude in the vertical direction changes linearly.

FIG. 3 shows a waveform of a sawtooth current applied to the correction coil 14 to correct the trapezoidal distortion 11a.

This sawtooth current is inclined in one direction with its midpoint being zero in one vertical cycle, and is applied to the raster correction coil 14 in synchronization with the vertical deflection frequency. Accordingly, an inclined correction magnetic field having a vertical one cycle similar to the sawtooth current is obtained in the raster correction coil 14, and this inclined correction magnetic field is superimposed on the scanning magnetic field of the deflection yoke 5 and applied to the electron beam L. .

Here, the scanning magnetic field of the deflection yoke 5 and the correction magnetic field of the raster correction coil 14 are represented by symbols A,
The points B and C correspond to each other, and the trapezoidal distortion 11a in FIG.
Is located in the lower right area AD centering on the substantially central portion B1 at the upper end side, and in the range AB above the screen, A of the sawtooth wave current shown in FIG.
A correction magnetic field is applied by the positive current in the region B, and the electron beam L is corrected so as to rise rightward. In addition, trapezoidal distortion 1
On the lower end side of 1a, it is located in an area EC that rises to the right around the substantially central portion B2, and in a range BC below the screen,
A correction magnetic field due to the negative current in the BC area of the sawtooth current applied to the correction coil 14 is applied to correct the electron beam L to the lower right. In this case, as the correction magnetic field, a large magnetic field in which the area AD on the upper end side of the screen and the area EC on the lower end side are inclined with respect to the center B of the screen is applied.
The upper and lower inclined portions are enlarged and corrected in the vertical direction as shown by arrows, and are corrected to normal square raster lines 11b as shown by dotted lines.

Since the center point of the sawtooth wave current applied to the raster correction coil 14 is set to zero, no correction magnetic field is applied to the center B of the screen, and the electron beam L applied to the center of the screen is not irradiated. No twisting occurs, and the landing position does not shift. Further, since the correction magnetic field is proportional to the peak value of the applied sawtooth current, raster 1
In the distortion correction of 1, the peak value may be appropriately adjusted according to the amount of distortion at the upper and lower ends.

Next, a description will be given of distortion correction of a parallelogram distortion raster whose upper and lower ends are inclined in parallel with each other.

FIG. 4 shows a pattern example of a parallelogram distortion 11c in which the raster 11 obtained by scanning the electron beam L in the cathode ray tube has a parallelogram shape in which the upper and lower ends are inclined in parallel to each other. As shown in the figure, the parallelogram distortion 11c is a parallelogram shape whose upper and lower ends are parallel to each other and inclined upward to the right, and the amplitude in the vertical direction changes linearly.

FIG. 5 shows the waveform of a sawtooth current applied to the correction coil 14 to correct the parallelogram distortion 11c.

This sawtooth wave current is inflected with the middle point being zero in one vertical cycle, and is inclined in the opposite direction with the middle point as a boundary. Similar to the trapezoidal distortion correction, the sawtooth current is synchronized with the vertical deflection frequency. And applied to the correction coil 14. Accordingly, an inclined correction magnetic field having a vertical one cycle similar to the sawtooth current waveform is obtained in the raster correction coil 14, and the inclined correction magnetic field is superimposed on the scanning magnetic field of the deflection yoke 5 and applied to the electron beam L. Is done.

Here, the scanning magnetic field of the deflection yoke 5 and the correction magnetic field of the correction coil 14 correspond to the points a, b and c in FIGS. 4 and 5, respectively, and correspond to the parallelogram distortion 11c in FIG. On the upper end side and the lower end side, they are applied to the correction coil 14 in the range ab on the upper end side of the screen and the lower end range bc on the screen including regions ad and ec rising to the right, both centering on the substantially central portions b1 and b2. A correction magnetic field due to the positive currents in the ab and bc regions of the sawtooth current shown in FIG. 5 is applied, and the electron beam L is corrected so as to be lowered to the left. In this case, as the correction magnetic field, a large magnetic field in which the region ad on the upper end side and the region ec on the lower end side of the screen are respectively inclined with respect to the center part b of the screen is applied. Are corrected downward as indicated by arrows, and are corrected to a normal square raster 11d as shown by the dotted line.

Also in the case of the parallelogram distortion 11c, since the midpoint of the sawtooth current applied to the raster correction coil 12 is set to zero, no correction magnetic field is applied to the center of the screen, and Without causing the electron beam L to twist
The landing position does not shift. Since the correction magnetic field is proportional to the peak value of the applied sawtooth current, the peak value may be appropriately adjusted according to the amount of distortion of the upper and lower ends of the raster 11.

In this embodiment, the raster distortion to be corrected is a trapezoidal distortion 11a in which the amplitude value on the right side gradually decreases, or a parallelogram distortion 11 in which the upper and lower ends are parallel to each other and inclined upward to the right.
Although c has been exemplified, raster distortion can be corrected in the same manner as long as the distortion has a shape in which the upper and lower ends of the raster are linearly inclined.

[0030]

As described above, according to the present invention, a raster correction coil for correcting raster distortion is provided near the deflection yoke on the outer periphery of the funnel of the cathode ray tube, and the sawtooth current synchronized with the vertical deflection frequency is provided in the correction coil. Is applied, the raster of trapezoidal distortion or parallelogram distortion can be corrected to a normal raster pattern. In addition, since the midpoint of the sawtooth wave current applied to the raster correction coil is set to zero, the electron beam at the center of the screen does not twist and the landing position does not shift. Not a good screen is obtained. Further, since the correction magnetic field is proportional to the applied saw-tooth current, the peak value thereof can be adjusted appropriately to cope with the amount of distortion of the raster image to be corrected, and the correction operation can be simplified.

[Brief description of the drawings]

FIG. 1 is a side view of one embodiment of a cathode ray tube of the present invention.

FIG. 2 is a pattern diagram of a trapezoidal distortion of a raster in an operation example of the cathode ray tube of FIG. 1;

FIG. 3 is a waveform diagram of a current applied to a raster correction coil to correct the distortion in FIG. 2;

FIG. 4 is a pattern diagram of raster parallelogram distortion in another operation example of the cathode ray tube of FIG. 1;

FIG. 5 is a waveform diagram of a current applied to a raster correction coil to correct the distortion in FIG.

FIG. 6 is a side view of a conventional cathode ray tube.

FIG. 7 is a pattern diagram of a normal raster.

FIG. 8 is a pattern diagram of upper and lower pincushion distortion of a raster.

FIG. 9 is a pattern diagram of a left and right pincushion distortion of a raster.

FIG. 10 is a pattern diagram of a horizontal deflection magnetic field for correcting pincushion distortion.

FIG. 11 is a pattern diagram of a vertical deflection magnetic field for correcting pincushion distortion.

FIG. 12 is a side view of a conventional cathode ray tube equipped with a degaussing coil for canceling a tube surface.

[Explanation of symbols]

 1 cathode ray tube bulb 2 neck 3 electron gun 4 funnel 5 deflection yoke 6 face panel 7 phosphor film 9 horizontal deflection coil 10 vertical deflection coil 11a trapezoidal distortion 11c parallelogram distortion 14 raster correction coil L electron beam

Claims (2)

(57) [Claims] An electron beam emitted from an electron gun housed in a neck of a cathode ray tube bulb is scanned by a deflection yoke mounted on the outer periphery of a funnel, and is irradiated on a fluorescent film formed on the inner surface of the face panel to be applied to the face panel. In a cathode ray tube forming a predetermined raster, a sawtooth synchronized with a vertical deflection frequency is provided near a deflection yoke on the outer periphery of the funnel in response to raster distortion formed in a trapezoidal shape in which the vertical amplitude changes linearly. And a raster correction coil for generating a vertical magnetic field for correcting raster distortion by applying a wave current. The cathode ray tube is characterized in that the generated current is a sawtooth current which is inclined in one direction with its midpoint being zero in one vertical cycle. 2. An electron beam emitted from an electron gun housed in a neck of a cathode ray tube bulb is scanned by a deflection yoke mounted on the outer periphery of a funnel, and irradiates a fluorescent film formed on the inner surface of the face panel to irradiate the face panel. In a cathode ray tube for forming a predetermined raster, a sawtooth current synchronized with a vertical deflection frequency is provided near a deflection yoke on the outer periphery of the funnel in response to a raster distortion formed by linearly changing upper and lower amplitudes. Is applied, a raster correction coil for generating a vertical magnetic field for correcting raster distortion is provided, and the raster distortion is applied to a raster distortion formed in a parallelogram shape whose upper and lower ends are inclined in parallel with each other. A cathode ray tube characterized in that the current is a sawtooth current in which the midpoint is inflected in one vertical cycle with the midpoint being zero, and the current is inclined in the opposite direction at the midpoint.