JPH0566705B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for correcting color cathode ray tubes.

[Conventional technology]

As is well known, the polarity adjustment of a shadow mask type color cathode ray tube is performed using the three B.
This is done by a pilot tailing adjustment to align the trajectory of the G/R electron beam with the light source position, and a longitudinal position adjustment to align the deflection center of the deflection yoke with the light source position. This adjustment improves the design and manufacturing accuracy of color cathode ray tubes and deflection yokes to ensure color uniformity across the entire display surface. Or super large 37
In inch color cathode ray tubes, the landing of the electron beam shifts (hereinafter referred to as mislanding), particularly at the corners of the display screen, resulting in extremely low error margin. This means that under natural geomagnetic conditions, it is not possible to ensure corner integrity just by adjusting the above.
The reason for this is that in the design of color cathode ray tubes, there is a problem with the design of the correction lens used when creating the fluorescent surface, and in manufacturing, there are problems with the reproducibility of shadow masks and the dimensional accuracy of panels, funnels, etc. Variations, variations in exposure equipment, etc. are involved in a complicated manner.

Next, we will explain the phenomenon in which mislanding reduces the readiness margin under geomagnetic conditions.

In Figure 4a, the horizontal component of geomagnetism (hereinafter abbreviated as B _H ) is zero, and the vertical component (hereinafter abbreviated as B _V ).
The above-mentioned precision adjustment is performed under a magnetic field condition of a certain strength, and the corner of the raster is placed in an ideal beam landing state without mislanding (hereinafter referred to as "just-landing"). A diagram showing a raster on which a certain striped phosphor is formed. Figure b is an enlarged diagram showing the beam landing state at the corner points (5 points). 1 is the raster, 2 is the black matrix, and 3 is the In the light-emitting part of the phosphor that emits light due to the impact of the electron beam 4, B, G, and R indicate the blue, green, and red light-emitting parts, respectively, and the dots (5 points) at the corner are just Indicates that it is in a landing state.

Normally, _BH always exists except in specific areas near the earth's polar regions, and in Japan it is approximately 0.3 Gauss. If a color cathode ray tube is installed with its tube axis horizontal in a place where such _BH exists, beam landing deviations will occur at the corners depending on the direction of the tube axis. Figures 5a to 5d are diagrams showing, with arrows, the directions in which the beam landing shifts at the corners (directions observed with a microscope) when color cathode ray tubes are installed facing east, west, south, and north, respectively. Arrow _5L indicates a state in which the electron beam impact position is shifted to the left, and arrow _5R indicates a state in which it is shifted to the right.

In this way, the phenomenon of beam landing deviation due to the presence of _BH always exists unless the magnetic shielding is perfect. In particular, since the display surface of a color cathode ray tube cannot be covered with a magnetic shielding member, when the tube axis is installed in the north-south direction,
The beam landings at the corners are shown in Figure 5c and d.
As shown in , it is impossible to avoid the phenomenon of deviation in the left and right rotational directions. Therefore, facing south,
Alternatively, when considering the case where a color cathode ray tube is installed facing north, it is necessary to adjust the corner portion to a state of zigzag stranding under the condition that _BH is zero. This means that under the condition that B _H is zero, if there is a leftward landing shift of 5 _L at the corner point P as shown in Figure 6a, if the color cathode ray tube is installed facing north, As shown in FIG. 6b, the mislanding at point P increases due to the addition of the leftward shift 5 _L , and as shown in the enlarged view, the electron beam 4 hits the adjacent phosphor, causing color unevenness. This is because it causes

FIG. 7 is a diagram for explaining the transition tolerance (hereinafter referred to as "other color tolerance") d until just before the electron beam hits the adjacent phosphor, and shows the width of the black matrix 2. B _M , the stripe width of the phosphor is S,
When the width of the electron beam 4 is W, it is defined as d=B _M -W-S/2.

[Problem that the invention seeks to solve]

In addition to the above-mentioned bolt tail adjustment and deflection yoke front/rear position adjustment, the conventional bolt tail adjustment method involves scanning raster 1 with a microscope video camera, etc. in order to prevent color unevenness at the corners as described above. Then, magnify and observe, and while looking at the position of the electron beam 4 hitting the phosphor, attach a correction magnet to the outer surface of the funnel of the color cathode ray tube, etc., for the best beam landing. The trajectory of electron beam 4 was corrected.

However, in this conventional method, in the corner of raster 1, the landing tendency is not necessarily the same between point P shown in Figure 6a and point Q nearby, so a large number of observation points are required. It is necessary to
In addition, the landing correction effect of the magnet, which is corrected by pasting it, differs depending on the location, so it is necessary to adjust the position and strength of the magnet several times, which is extremely inefficient. .

This invention was made in order to solve the above-mentioned problems, and it is possible to macroscopically check the landing state over the entire surface of the raster, and it is possible to carry out predetermined pilotage adjustment work very efficiently. The purpose of the present invention is to provide a method for correcting color cathode ray tubes.

[Means for solving problems]

A color cathode ray tube correction method according to the present invention applies an alternating current magnetic field of a frequency different from a vertical deflection magnetic field in a predetermined direction to a color cathode ray tube in which a raster is drawn by an electron beam of a shadow mask type color cathode ray tube. [Operation] This invention is characterized by disposing a correction magnet in the color cathode ray tube so as to displace the electron beam at a low frequency and, at this time, forcibly eliminate color unevenness occurring in the raster. According to the above, a color cathode ray tube that draws a raster with the electron beam of a shadow mask type color cathode ray tube is installed in an environment with no magnetic field in the plane direction including the tube axis, and then the color cathode ray tube is exposed to a vertical deflection magnetic field. When alternating current magnetic fields of different frequencies are applied in a predetermined direction, the trajectory of the electron beam is shifted, and color unevenness occurs in areas where there is no deviation. Change.

Here, the color adjustment operator who is observing the raster can forcibly eliminate the color unevenness occurring in each part of the raster by arranging a correction magnet to increase the strength of the applied alternating current magnetic field. For the geomagnetic component corresponding to the magnetic field and the direction thereof, it is possible to easily perform the right correction so that the other color printing latitude is in the best state.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a perspective view showing a device for adjusting the environment of a color cathode ray tube or a color television receiver, in which 10 _H includes a tube axis of a color cathode ray tube 11 placed horizontally. A pair of Helmholtz coils, 10 _V , cancel out the earth's magnetic field B _H applied in the plane direction so that it becomes zero, so that the strength of the vertical magnetic field applied to the color cathode ray tube 11 is the same as the B _V in the area where it is used. In the pair of Helmholtz coils 10 _H and 10 _V , appropriate amounts of direct current are supplied from a power source (not shown), respectively.

As shown in FIG. 2, the color cathode ray tube 11 is equipped with a coil 12 that generates a magnetic field in the direction of the tube axis.The color cathode ray tube 11 is equipped with a coil 12 that generates a magnetic field in the tube axis direction. An alternating current is applied. At the same time, the color cathode ray tube 11 displays a red raster on the screen 1 when a predetermined scan is performed by operating only a single red electron beam among its electron beams.

In this way, when an alternating current magnetic field of a predetermined strength in the direction of the tube axis is applied by the coil 12 in an environment where B _H is zero and B _V is a predetermined strength, as shown in FIGS. Left-handed and right-handed beam landing shifts occur alternately, and change at a frequency of 10 Hz, which is the difference frequency between the vertical deflection frequency and the applied alternating current magnetic field frequency. If the strength of the alternating current magnetic field applied by the coil 12 is set to a displacement amount that does not exceed the other color printing tolerance d in the case of a straight stranding state, then in the case of a straight stranding, as shown in FIG. As shown in a, the light emitting part 3 of the phosphor
is only displaced within the range shown by the one-dot chain line and the two-dot chain line, so color unevenness does not occur. On the other hand, as shown in Figure 3b, if the beam landing is shifted to the left, when the electron beam is displaced to the position shown by the dashed-dotted line, it will hit the green phosphor and change color. Unevenness occurs, and this uneven color appears at a frequency of 10Hz. Such a change in color unevenness appears in each portion that is not in a state of jiast stranding, so that an adjustment operator observing raster 1 can easily visually recognize it. Therefore, the adjustment operator places a correction magnet 13 on the outer surface of the funnel corresponding to the area where uneven coloring occurs, and adjusts its polarity, strength, and By sequentially performing the position selection process for each part where color unevenness occurs, it is possible to efficiently perform the unevenness correction suitable for the area where the color cathode ray tube is used.

In the above embodiment, the alternating current flowing through the coil 12 is 50 Hz, and the fluctuation period of the beam landing is
Although the frequency is set to 10 Hz, it may be set to a frequency slightly different from the vertical deflection frequency, and may vary at a slow period of several Hz.

In the above embodiment, the amount of current applied to the coil 12 was set to a value that does not exceed the other color printing tolerance d, but this means that if the strength exceeds the other color printing tolerance d, even in the part of the deviation This is because color unevenness occurs, making it difficult to judge whether or not the image quality adjustment is appropriate.

Further, in the above embodiment, the coil 12 is provided for applying an alternating magnetic field in the direction of the tube axis. If so, you can use that coil.

Furthermore, although the above embodiment shows an example in which an alternating magnetic field is applied in the tube axis direction of a color cathode ray tube, the application is not limited to this direction. If the receiving direction is other than north-south, e.g.
Needless to say, if the direction is the east-west direction of _BH or any other direction including the vertical component _BV , it is sufficient to provide a coil 12 that generates an alternating magnetic field in that direction.

Note that the alternating current flowing through the coil 12 may be a sine wave or a square wave, but its amplitude is important.

Furthermore, in the above embodiment, the Helmholtz coil _10H is used to set _BH to 0, but if the AC current flowing through the coil 12 includes a DC component, the Helmholtz coil _10H can be omitted. be able to.

〔Effect of the invention〕

As described above, according to the present invention, a color cathode ray tube that draws a raster with the electron beam of a shadow mask type color cathode ray tube is installed under an environmental condition in which the earth's magnetic field _BH is zero, and An alternating current magnetic field with a frequency different from that of the deflection magnetic field is applied in a predetermined direction to displace the electron beam at a low frequency, and a correction magnet is installed to eliminate color unevenness occurring in each part of the raster. Since this is a mislanding correction method that applies a magnetic field, if the mislanding correction is incomplete, the position of the part that does not have mislanding accompanied by color unevenness and the degree of mislanding will depend on the vertical deflection magnetic field and the frequency of the applied alternating current magnetic field. It appears on the raster with a period of difference of , so
Can be easily recognized visually. Furthermore, rather than observing locally using a microscope, the landing state over the entire surface of the raster can be visually confirmed macroscopically.

Therefore, the correction effect of the correction magnet can be directly observed, and it is also possible to determine whether or not the image is in a state of deviation from the presence or absence of color unevenness. Color cathode ray tubes are capable of performing image correction with a tolerance for color printing that best suits the area corresponding to the applied alternating magnetic field.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a device for adjusting the environment of a color cathode ray tube that performs pulse adjustment according to the present invention, FIG. 2 is a perspective view showing an alternating current magnetic field applying coil used in the present invention, and FIGS. b is a diagram for explaining the displacement of the electron beam due to the applied alternating magnetic field, Figures 4a and b are diagrams for explaining the state of jiast landing, and Figures 5a to d are the directions of the color cathode ray tube. Figures 6a and b are diagrams to explain the influence of geomagnetism in the case of mislanding. FIG. 3 is a diagram for explaining the latitude for printing other colors. 1...Raster, 2...Black matrix,
3... Light-emitting part of phosphor, 4... Electron beam, 1
0 _H , 10 _V ...Helmholtz coil, 11...Color cathode ray tube, 12...AC magnetic field generation coil, 1
3...Correction magnet. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An alternating current magnetic field with a frequency different from the vertical deflection magnetic field is applied in a predetermined direction to a color cathode ray tube whose electron beam forms a raster pattern using a shadow mask type color cathode ray tube. 1. A color cathode ray tube correction method, comprising disposing a correction magnet in the color cathode ray tube so as to forcibly eliminate color unevenness occurring in the raster when the color cathode ray tube is displaced. 2. Adjust the strength of the alternating current magnetic field applied to the color cathode ray tube to within a range where the amount of beam landing movement caused by the application of the alternating magnetic field does not exceed the other color printing tolerance based on the design value of the color cathode ray tube. A color cathode ray tube correction method according to claim 1. 3. A color cathode ray tube correction method according to claim 1, wherein the frequency of the alternating current magnetic field applied to the color cathode ray tube is several Hz different from the frequency of the vertical deflection magnetic field. 4. A color cathode ray tube correction method according to claim 1, wherein the direction of the alternating current magnetic field applied to the color cathode ray tube is the direction in which the color cathode ray tube causes the most mislanding due to earth's magnetism. 5. The color cathode ray tube according to claim 1, wherein the alternating current magnetic field applied to the color cathode ray tube is generated by passing an alternating current through a magnetic cancel coil for geomagnetic correction mounted on the color cathode ray tube. Piyuri correction method.