JPH021345B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a network for a single electron gun type cathode ray tube.
The present invention relates to a high resolution cathode ray tube device equipped with a quadrupole magnetic field generator for correcting astigmatism distortion.

In general, cathode ray tubes used in data display devices are required to have the same high resolution at the periphery of the phosphor screen as at the center. However, since the electron beam in a cathode ray tube is greatly affected by aberrations as the amount of deflection increases, beam spots (bright spots) that occur around the periphery of the phosphor screen 1 as shown in FIG.
2, 3, and 4 are longer than the beam spot 5 formed at the center of the phosphor screen 1, and the resolution at the periphery is lower.

On the other hand, since the known dynamic focus correction as a measure against such distortion is correction using an axially symmetrical lens, the size and shape of the beam spot 3 generated near the corner of the phosphor screen 1 can be adjusted as shown in FIG. Even if it can be improved, it cannot improve the size and shape of the beam spots 2, 4 that occur near the periphery on the central vertical axis and near the periphery on the central horizontal axis. In the vicinity of the corner, the distortion caused by the horizontal deflection and the distortion caused by the vertical deflection cancel each other out, so that almost no astigmatic distortion occurs in the beam spot.

In the cathode ray tube device of the present invention, a quadrupole magnetic field generator is used to prevent the occurrence of astigmatic distortion, and this will be explained below in conjunction with an embodiment shown in the drawings.

In FIG. 3, the cathode ray tube 6 includes an electron gun 13 consisting of a cathode 7, a control electrode 8, a first accelerating electrode 9, a focusing electrode 10, a second accelerating electrode 11, an electrode supporting insulator 12, etc. It is provided internally and has a phosphor screen 16 on the inner surface of the face panel section 15. A quadrupole magnetic field generator 17 and a deflection yoke 18 are attached to the outer peripheral surface of the neck portion 14.

The quadrupole magnetic field generator 17 is provided at a position surrounding the focusing electrode 10, and includes four solenoid coils 19, 20, 21,
It has 22. Coil shafts 19a, 20a, 2
1a and 22a are located on a plane perpendicular to the axis 23 of the neck portion 14 and are inclined at an angle of 45 degrees with respect to the horizontal deflection axis 24, and adjacent ones are arranged with an angular difference of 90 degrees. has been done.

The four solenoid coils 19, 20, 21, and 22 connected as shown in FIG. 5 generate a magnetic field in the direction shown by the solid arrow 25 when energized in the direction shown by the broken arrow. That is, the solenoid coils 19, 20, 21, 22 are connected to the focusing electrode 10.
A magnetic field with the polarity shown in FIG. 6 is applied to the electron beam passing through the phosphor screen, that is, a quadrupole magnetic field with N poles at the upper right and lower left and S poles at the lower right and upper left when viewed from the phosphor screen side. Therefore, the shape of the beam spot 26, which is distorted into a horizontally oblong ellipse due to horizontal deflection, can be made closer to a perfect circle.

In addition, solenoid coils 19, 20, 21, 2
When a quadrupole magnetic field with the polarity as shown in FIG. 7 is applied to the electron beam by reversing the direction of the current flowing through the electron beam 2, the shape of the beam spot 27 is distorted into a vertically elongated ellipse due to the vertical deflection effect. can be made close to a perfect circle.

In horizontal deflection (or vertical deflection), the magnitude of the current flowing through the solenoid coils 19, 20, 21, and 22 is large at both the left and right ends (or at both the top and bottom ends) of the phosphor screen, and at the center of the phosphor screen. The ideal is a quadratic curve that becomes zero at . However, even if it is not a parabolic wave current as shown by the broken line in a of FIG. 8, a triangular wave current as shown by the solid line is sufficient. Such a triangular wave correction current can be extracted from the deflection output circuit of the television receiver through a waveform shaping circuit, and is synchronized with the sawtooth wave deflection current shown in FIG. 8b.

Therefore, in addition to performing the same dynamic focus correction as in the past, the four solenoid coils 19 and 2 connected as shown in FIG.
0, 21, and 22, if a parabolic wave or triangular wave current synchronized with the horizontal deflection current is passed in one direction, and a parabolic wave or triangular wave current synchronized with the vertical deflection current is passed in the opposite direction, the horizontal deflection and vertical It is possible to almost completely eliminate astigmatic distortion of the beam spot caused by deflection, and it is possible to generate a beam spot that is close to a perfect circle even at the periphery of the phosphor screen, achieving good resolution across the entire screen. Can be done.

The quadrupole magnetic field generator 17 is installed at a location where it is not affected by the deflection magnetic field, but it is preferably selected at a location where the potential of the electron beam is low. If it is installed at a location with the same potential as the phosphor screen, power consumption will increase. As an example, the deflection angle
A solenoid coil with 100 turns each (wire diameter 0.3 mm, L = 626 μH, R = 6.8 Ω) was installed on the outer periphery of the focusing electrode of an 18-inch monochrome cathode ray tube with a diameter of 110° and a neck diameter of 29.1 mm, and a phosphor screen was installed. When the voltage (anode voltage) is 18kV and the focusing electrode voltage is 4.9kV,
The optimal correction current is 350 mA at the left and right ends on the central horizontal axis of the phosphor screen, and 200 mA at the top and bottom ends on the central vertical axis of the phosphor screen.
Astigmatic distortion of the beam spot can be corrected with a power that is a fraction of the deflection power. When the distance from the center of the phosphor screen to the periphery on the central horizontal axis was plotted on the horizontal axis and the beam spot diameter was plotted on the vertical axis, the characteristics shown in FIG. 9 were obtained. However, here, curve A is obtained when dynamic focus correction is not performed.
Curve B shows the case when the same correction is performed, and curve C shows the case when dynamic focus correction and astigmatism distortion correction of the present invention are performed.

[Brief explanation of drawings]

1 and 2 are plan views schematically showing the shape of beam spots generated on the phosphor screen of a conventional cathode ray tube device, and FIG. 3 is a partially cutaway side view of a cathode ray tube device according to the present invention. , Fig. 4 is a layout diagram of the four solenoid coils of the quadrupole magnetic field generator of the same device, Fig. 5 is a wiring diagram of the solenoid coil,
6 and 7 are diagrams showing the relationship between the magnetic field generated by the quadrupole magnetic field generator and the electron beam cross section,
Fig. 8 is a waveform diagram showing the relationship between the correction current and the deflection current flowing to the quadrupole magnetic field generator, and Fig. 9 compares the beam spot diameter characteristics of a conventional cathode ray tube device and a cathode ray tube device according to the present invention. It is a diagram. 6... Cathode ray tube, 17... Quadrupole magnetic field generator, 1
9, 20, 21, 22... Solenoid coil.

Claims (1)

[Claims] 1 A quadrupole magnetic field generator attached to the neck of a single electron gun type cathode ray tube activates four solenoid coils, one each placed at the upper right, lower left, upper left, and lower right around the axis of the neck. The solenoid coils are connected to each other in such a direction that the upper right and lower left become N poles, and the upper left and lower right become S poles, and generate a parabolic wave or a parabolic wave synchronized with the horizontal deflection current. Triangular wave current in one direction,
The cathode ray tube device is connected to a correction current generation circuit that flows parabolic wave or triangular wave currents in opposite directions in synchronization with the vertical deflection current to generate a quadrupole magnetic field for astigmatism correction.