JPS6337793A - Doming correcting circuit - Google Patents

Abstract

PURPOSE:To prevent color shading from being generated by connecting a coil driving circuit for purity correction, a microcomputer, and a correction data memory and correcting the doming during the operation of a cathode-ray tube. CONSTITUTION:A correcting coil 6 provided behind a deflection coil 2 consists of four coils 6a-6d, which are connected in series. A beam position correcting coil is connected to the microcomputer 8 and memory 9 through a driving circuit 7, and the memory 9 is stored with correction data matching with doming characteristics of the cathode-ray tube. The computer 8 reads correction data corresponding to the elapsed time from the start of the operation of the cathode- ray tube out of the memory 9 and supplies a current to the coil to produce a correcting magnetic field. Consequently, variation in purity with time corresponding to the secular doming characteristics of the cathode-ray tube can be corrected and the generation of a color shape during the operation of the cathode-ray tube is easily controlled.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to color unevenness in shadow mask type color cathode ray tubes, and in particular, to properly correct doming during operation of the cathode ray tube and prevent the occurrence of color unevenness. .

[Conventional technology]

As a conventional privacy correction circuit,
As described in Japanese Patent No. 284, a DC power source and a variable resistor were connected to the coil to perform a certain purity correction. However, no consideration was given to dynamic changes in purity such as doming.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not consider dynamic correction of the purity, and does not make any correction for changes in the purity during cathode ray tube operation such as doming.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a correction circuit that can also correct temporal changes in purity during operation of a cathode ray tube, that is, doming.

[Means for solving problems]

The above object is achieved by changing the current flowing through the correction coil over time using a microcomputer.

[Effect]

The correction data is stored in the memory in advance in accordance with the characteristics of the cathode ray tube, thereby making it possible to correct the average doming during operation of the cathode ray tube.

〔Example〕

In FIG. 1, numeral 1 represents a shadow mask type color cathode ray tube, and numeral 2 represents a deflection coil. The three red, green, and blue electron beams emitted from the electron gun 3 pass through the holes in the shadow mask 4 to form red, green, and blue electron beams on the fluorescent surface 5.
It hits a blue phosphor and emits light.

During operation of the cathode ray tube, the movement of the electron beam on the fluorescent surface 5 due to thermal expansion of the shadow mask 4 is in the direction of the arrow shown in FIG. The change in purity can be corrected by generating .

Reference numeral 6 indicates a beam position correction coil according to the present invention, which is provided behind the deflection coil 2. Beam position correction coil 6
is composed of four coils 6a to 6d as shown in FIG. 2, and connected as shown in FIG. When four coils are connected as shown in FIG. 2 and a current is applied, the magnetic field generated by the coils becomes oriented in the direction shown in FIG. 4 on the surface of the cathode ray tube panel.

The beam position correction coil is connected to a microcomputer 8 and a memory 9 via a drive circuit 7.

The memory 9 stores the doming characteristics of the cathode ray tube (Fig. 5, 10).
Pre-store correction data suitable for the purpose.

The microcomputer 8 reads correction data corresponding to the elapsed time from the start of operation of the cathode ray tube from the memory 9, and applies current to the coil via the drive circuit 7 to generate a correction magnetic field B.
to occur.

〔Effect of the invention〕

According to the present invention, it is possible to correct the temporal change in purity corresponding to the temporal doming characteristic of the cathode ray tube, so that it is possible to easily suppress the occurrence of color unevenness during the operation of the cathode ray tube.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a shadow mask type color cathode ray tube in which the present invention is implemented, Fig. 2 is a block diagram of the doming correction circuit of the present invention, and Fig. 3.4.5 is the principle of doming correction according to the present invention. FIG. 3 shows the direction in which the purity changes due to doming, FIG. 4 shows the direction of the magnetic field to be corrected, and FIG. 5 shows the general doming characteristics.

Claims (1)

[Claims] 1. The purity correction coil device attached to the neck of the cathode ray tube is connected to a drive circuit that drives it, a microcomputer that controls it, and a memory that stores correction data, thereby properly correcting doming during cathode ray tube operation. A doming correction circuit for a shadow mask type color cathode ray tube.