JPH0352167B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for correcting convergence and polarity errors in a color picture tube, in which a magnetic pole is provided in or around the neck of the tube housing and around the electron beam path. The present invention relates to a method of manufacturing a color picture tube which is formed by magnetizing a permanent magnet member that generates a permanent static magnetic field and has the magnetic poles provided around an electron beam path.

The color picture tube is equipped with an electron gun that emits three electron beams that cause three types of phosphors to emit light separately, emitting red, green, and blue colors. The three electron beams must be concentrated on the image receiving screen surface, and if they are not concentrated, normal color development will not occur. Further, each electron beam must be correctly incident on the corresponding phosphor after passing through a shadow mask.
If the light does not enter the corresponding phosphor accurately, not only will it not produce the correct color, but it will also enter other phosphors, resulting in a completely different overall color. For this reason, color picture tubes are assembled with great precision. However, certain errors may occur in static convergence and color purity due to unavoidable errors such as assembly errors of the electron gun, dimensional errors of electron gun parts, sealing errors of the electron gun, and sealing errors between the panel and funnel. Since these errors cannot be avoided, these errors must be corrected in some way. Normally, a permanent magnet magnetized with two poles, four poles, and six poles is installed in the path of the electron beam at the neck of a color picture tube, and this permanent magnet is adjusted manually.

However, such adjustment requires great skill and takes a long time. Therefore, in recent years, in order to improve the performance and reduce costs of color picture tubes, permanent magnet members have been installed in the middle of the electron beam path inside and outside the network of color picture tubes, and these members are magnetized after the color picture tube has been assembled. A method for correcting convergence and integrity errors has been proposed, for example, in Japanese Patent Application Laid-Open No. 122322/1983. In this method, a color picture tube is first operated, and then data regarding the value and direction of the convergence error of the electron beam are determined, and based on these data, the magnetic poles are adjusted to correct the convergence error occurring in the color picture tube. Determine direction and intensity. This method requires displaying the screen and reading it in some way. The position of this image is detected using a television camera or a solid-state device. However, as a method of magnetizing a permanent magnet, a method of demagnetizing after saturation magnetization is used in order to reduce the change over time after magnetization. This method is indispensable especially for magnets for color picture tubes, which require precise magnetization and cannot be allowed to change over time. Therefore, the method used is to first saturate the magnet with a very strong magnetic field and then demagnetize it with a magnetic field of appropriate magnitude and direction. The problem at this time is that because the three electron beams in the color picture tube are initially magnetized by a very strong magnetic field, they are deflected very strongly, causing them to deviate greatly from their initial positions on the screen of the color picture tube. It's something that happens. The direction and amount of this shift of the electron beam vary greatly depending on the magnitude and direction of the initial error, so the direction and amount cannot be predicted in advance. Therefore, the error detection detector must detect a large deviation after saturation magnetization, and therefore must detect a very wide range on the screen. Therefore, detection accuracy becomes extremely poor. Normally, errors such as color shift on the screen of color picture tubes are a problem of about 0.1 mm, so this decrease in detection accuracy is a fatal drawback. Therefore, methods are being used to mechanically change the precision and magnification, or to improve the precision by using a precise detector. However, all of these methods lead to a significant increase in cost and require a lot of time to adjust as various additional functions are added.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a method for manufacturing a color picture tube that detects errors on a color picture tube screen in a simple and precise manner.

In the method of manufacturing a color picture tube of the present invention, a static convergence correction device is provided, a permanent magnet that can be magnetized is provided inside or outside the neck portion, and after saturation magnetization, a permanent magnet is formed using three electron beams. The method is characterized in that demagnetization is performed using an alternating current magnetic field so that each of the three color images is within the detection range of the detector.

According to one embodiment of the method for manufacturing a color picture tube of the present invention, a magnetic pole and coil for magnetization and a demagnetizing magnetic pole and coil for demagnetization can be provided around a permanent magnet for convergence and pillality correction.
Further, the magnetizing magnetic pole and the demagnetizing magnetic pole or the magnetizing coil and the demagnetizing coil can be used in common.

To enable uniform AC demagnetization after saturation magnetization for convergence and pulley adjustment, more precise demagnetization can be performed, AC demagnetization magnetic poles and coils are placed outside of the magnetization magnetic poles and coils. It is also possible to place

Multiphase AC is convenient for the magnetic field for AC demagnetization because it is necessary to very uniformly demagnetize the permanent magnets for convergence and integrity correction. If polyphase alternating current is used, a uniform alternating current demagnetizing field can be applied to the convergence/pilarity correction magnet. Even when a two-phase alternating current magnetic field is used, it is possible to create a uniformly attenuated alternating magnetic field by appropriately shifting the phase using, for example, a capacitor.

Further, the number of permanent magnets for convergence and integrity correction may be one or more, and it is of course possible to demagnetize only the magnet that deflects the electron beam particularly greatly.

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

FIG. 1 is a configuration diagram showing an example of a magnetization device used in the method of manufacturing a color picture tube of the present invention. An electron gun 5 equipped with a permanent magnet 4 for convergence/pilarity correction is disposed within the color picture tube bulb 1, and is electrically connected to the outside of the color picture tube by a stem pin 12. The convergence/pilarity error of the color picture tube is detected by operating the color picture tube and outputting an appropriate image to the color picture tube and detecting the detector 8.
to detect the position of the signal. A control device 9 calculates a convergence error of the color picture tube based on the position of the signal. Based on this result, a magnetizing power source 10 is operated to energize the magnetizing magnetic pole 6 and magnetize the permanent magnet 4. Thereafter, the AC demagnetizing power supply 11 is operated to energize the AC demagnetizing and demagnetizing magnetic poles 7, thereby demagnetizing the permanent magnets 4.

FIG. 2 is a schematic diagram showing an example of a magnetizing magnetic pole. The magnetic pole frame 13 is provided with multiple magnetic poles, and a magnetizing coil 15 is connected to each magnetic pole. Further, the coil 15 can be used not only for magnetization but also as a coil for AC demagnetization and demagnetization. Moreover, the magnetic pole for magnetization can also be used as the magnetic pole for AC demagnetization and demagnetization.

FIG. 3 is a schematic diagram showing magnetic poles for AC demagnetization and demagnetization. The example shown in FIG. 3 is an example of a magnetic pole having six magnetic poles and generating a magnetic field for demagnetization and demagnetization using three-phase alternating current.

That is, the magnetic pole shown in FIG. 3 forms a rotating alternating current magnetic field inside the magnetic pole. A three-phase AC voltage is applied to the terminal 16, and the AC magnetic field may be placed near the permanent magnet 4 or may be placed so as to surround the magnetizing magnetic pole 4 on the permanent magnet.

Figures 4a, b, and c show examples of convergence errors in color picture tubes, examples when the permanent magnet 4 is saturated magnetized, and examples when AC demagnetization is performed to correct the convergence errors. .

In FIG. 4a, it is assumed that a red circle image 19, a green circle image 20, and a blue circle image 21 are lined up from the left in the detection range 18 on the color picture tube screen 17. In order to correct the error shown in a, the blue circle image 21 and the green circle image 2 should be
0 and the red circle image 19 are arranged in this order.Saturation enhancement is performed. At this time, if the detection range is made small so that the amount of convergence integrity error can be detected accurately, the detection range will be outside the detection range 18 as shown in FIG. 4b, and detection will be impossible, so care must be taken. After this, if demagnetization is performed in an AC demagnetizing field, the fourth
As shown in Figure c, within the detection range 18 from the left, a blue circle image 21, a green circle image 20, and a red circle image 19
They are entered in this order and can be detected.

The above can be similarly obtained when demagnetizing with a reverse magnetic field of an appropriate magnitude after saturation magnetization.

Thereafter, as in the conventional example, the permanent magnet is demagnetized based on convergence and purity error data obtained from the screen of the color picture tube after demagnetization. Such data acquisition and demagnetization are normally not carried out once, but are carried out until it is determined that the convergence and purity errors of the color picture tube are good, but if the errors are sufficiently small, it may be carried out once.

As described above, according to the method of manufacturing a color picture tube of the present invention, even when the convergence-pilarity error is large, the image position can be detected without degrading the detection accuracy of the convergence-pilarity error, and the complicated device Detection that does not require much time becomes possible.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of a magnetizing device according to the method of manufacturing a color picture tube of the present invention, Fig. 2 is a schematic diagram showing the structure of magnetizing magnetic poles, and Fig. 3 is a schematic diagram showing magnetic poles for AC demagnetization and demagnetization. Schematic diagram showing Figure 4 a, b, c
is a schematic diagram for explaining the procedure of AC demagnetization. DESCRIPTION OF SYMBOLS 1... Color picture tube, 2... Color picture tube neck part, 3... Deflection yoke, 4... Permanent magnet, 5...
...electron gun, 6... magnetic pole for magnetization, 7... magnetic pole for demagnetization, 8... detector, 9... control device, 10...
Magnetizing current, 11...Reduction, demagnetizing power supply, 12...Stem pin, 13...Magnetic pole frame, 14...Magnetic pole, 15...
... Coil, 16 ... Three-phase AC power supply, 17 ... Color picture tube screen, 18 ... Detection range, 19 ... Red circle image, 20 ... Green circle image, 21 ... Blue circle image.

Claims (1)

[Scope of Claims] 1. A face plate having a phosphor layer adhered to the inner surface thereof, which has a regularly arranged phosphor layer that develops colors of red, green, and blue upon impingement of an electron beam, and said face plate. Netsuku, which faces the electron gun inside,
a shadow mask having a large number of openings arranged opposite to the fluorescent surface at predetermined intervals and supported by the face plate via a support structure; and attached to the outer wall of a funnel connecting the neck part and the face plate. In the method for manufacturing a color picture tube, which is equipped with a deflection device and a permanent magnet for adjusting convergence and purity on the inside or outside of the tube near the neck portion, the color picture tube is first operated, and the screen of the color picture tube is After the permanent magnet is saturated and magnetized using the convergence and pipulity error data obtained from the process, it is demagnetized with an alternating current magnetic field so that the convergence and pipulity detection device of the color picture tube can easily detect the permanent magnet. A method for manufacturing a color picture tube, characterized in that the permanent magnet is demagnetized based on data on convergence and purity errors obtained from the screen of the color picture tube after magnetization. 2. The method of manufacturing a color picture tube according to claim 1, wherein after the saturation magnetization, demagnetization is performed using a magnetic field in a direction opposite to the saturation magnetization.