JPH0454092A - cathode ray tube - Google Patents

Abstract

PURPOSE:To correct dynamically a convergence of an intermediate part by supplying a vertical deflection current to an auxiliary coil so as to generate a magnetic field causing reverse deflection to predeflection due to a leakage magnetic field by means of the auxiliary and adjusting a magnetic sturation characteristic of a core of the auxiliary coil and using a vertical deflection current when an electron beam is deflected to the intermediate position in the vertical direction so as to saturate the core of the auxiliary coil magnetically. CONSTITUTION:An auxiliary coil 18 and a core 19 are provided to a rear side of a deflection yoke 19 of a CRT 10, that is, at the side of an electron gun 15. Then a vertical deflection current is supplied to the auxiliary coil 18 to generate a magnetic field 20 thereby applying pre-deflection to the electron beam. The beam is deflected as shown in solid lines by applying pre-deflection. The current supplied to the auxiliary coil 18 is increased in response to the deflection and since the core 19 is saturated after the intermediate part in the vertical direction, the increase in the generated magnetic field is not caused and the quantity of pre-deflection is unchanged.

Description

[Detailed description of the invention]

Field of Industrial Application] The present invention is applied to CRT (Cathode Ray Tube).
(cathode ray tube), and particularly relates to a deflection yoke that is equipped with a horizontal deflection coil and a vertical deflection coil and that is attached from the funnel section to the neck section of a CRT. K Summary of the Invention 1 This relates to the modification of the convergence of a deflection yoke, in which an auxiliary coil is provided behind the deflection yoke and on the electron gun side, and the electron beam is controlled by the auxiliary coil to have a vertical deflection period before entering the deflection yoke. By changing the amount of deflection, mid-layer misconvergence is corrected.

[Conventional technology]

In a color CRT, when the three R, G, and B electron beams are deflected by the deflection coil, the three electron beams must be focused on exactly the same point in any part of the aperture grill. . However, since the distance from the center of deflection to the aperture grill is different between the center and the periphery of the screen, if the three beams are aligned at the center and concentrated at a predetermined position on the aperture grill, the distance from the center of the screen to the aperture grill is different. In this case, three beams do not pass through the same slit, causing color shift. In order to correct such defects, a convergence coil is used. In addition, the trinitron tube, in which three electron beams are arranged in-line, is a convergence-free CR system that does not require a convergence coil.
T is now supplied. Problems to be Solved by the Invention The deflection yoke of a convergence-free CRT distorts the deflection magnetic field to match the convergence of the corners of the screen in the X-axis direction and the Y-axis direction. However, with such a convergence-free deflection yoke, as shown in FIG. 6, an intermediate misconvergence occurs in which the convergence does not match in the vertically intermediate portion of the left and right ends. Such intermediate misconvergence is extremely difficult to correct, and is the biggest problem in achieving high convergence accuracy. An object of the present invention is to provide a CRT deflection yoke that corrects such intermediate misconvergence. Means for Solving Problem K] The present invention provides a deflection yoke that is equipped with a horizontal deflection coil and a vertical deflection coil and is installed from the funnel section to the neck section of a CRT. An auxiliary coil is provided on the electron gun side, and a vertical deflection current is passed through the auxiliary coil so that the auxiliary coil generates a magnetic field that causes a deflection in the opposite direction to the pre-deflection due to the leakage magnetic field, and the magnetism of the core of the auxiliary coil is The saturation characteristics are adjusted so that the core of the auxiliary coil is magnetically saturated by the vertical deflection current when the electron beam swings vertically to an intermediate position. 1 Effect] Therefore, the core of the auxiliary coil, which generates a magnetic field that causes deflection in the opposite direction to the pre-deflection due to the leakage magnetic field, becomes magnetically saturated when the vertical deflection current reaches the current pot that swings the electron beam to the middle part. , such magnetic saturation characteristics make it possible to improve misconvergence in the intermediate region.

【Example】

FIG. 1 shows a CRTIO according to an embodiment of the present invention, and this CRTIO is composed of a trinitron tube that emits three electron beams in-line. A deflection yaw 11 is attached from the funnel section to the neck section of the CRTIO. The deflection yoke 11 has a horizontal deflection coil 12 and a vertical deflection coil 13.
It is composed of. The horizontal deflection coil 12 is composed of a saddle-shaped coil. On the other hand, the vertical deflection coil 13 is composed of a toroidal coil, and is attached to the outside of the horizontal deflection coil 12 while being wound around the core 14 . Further, an electron gun 15 is housed inside the neck portion of the CRT. An auxiliary coil 18 is disposed on the rear side of the deflection yoke 11 and on the electron gun 15 side. The auxiliary coil 18 is wound around the upper and lower cores 19, respectively, as shown in FIG. The auxiliary coil 18 generates a magnetic field 20 as indicated by the arrow in FIG. Note that this magnetic field 20 is a vertical deflection magnetic field 21
It is designed to be generated in synchronization with the That is, the auxiliary coil 18 is connected in series with the vertical deflection coil 13, as shown in FIG.
It is designed to be driven by Moreover, the core 19 around which the auxiliary coil 18 is wound has a magnetic saturation characteristic as shown in FIG.
is magnetically saturated. As described above, in the CRTlo according to this embodiment, the auxiliary coil 18 and the core 19 are provided on the rear side of the deflection yoke 11, that is, on the electron gun 15 side. and the third
A vertical deflection current is passed through the auxiliary coil 18 using a circuit as shown in the figure to generate a magnetic field 20 to pre-deflect the electron beam. If pre-deflection is not performed, the beam will take a path as shown by the dotted line in FIG. 1, whereas by performing pre-deflection, the beam will be deflected as shown by the solid line in FIG. Therefore, such pre-deflection is expected to increase the neck shadow margin. Furthermore, the pre-deflection of the electron beam by the auxiliary coil 18 is equivalent to the electron beam being upwardly off-axis, resulting in a convergence pattern as shown in FIG. Similarly, if it is pre-deflected downward, the result will be as shown in FIG. 4B. Therefore, by performing pre-deflection in the vertical deflection period, the fourth
The pattern will look like Figure C. Here, the core 19 of the auxiliary coil 18 that generates the pre-deflection magnetic field is made to have a low saturation magnetic density as shown in Figure 5, and the deflection current when deflecting outward from the middle part of the screen is used. I'm trying to get it saturated. The current flowing in the auxiliary coil 18 increases according to the deflection, but after the vertical middle part, the current flowing in the core 1
9 is saturated, the generated magnetic field does not increase and the amount of pre-deflection remains unchanged. Therefore, C in Figure 4C
The amount of change in misconvergence called CV and MCv becomes the same. On the other hand, when the main deflection magnetic field by the deflection coil 13 is distorted to change the CCV, the change in MCV is approximately 1/2 of CCv. As a result, the MCV is corrected. The direction of correction in this case is determined by the directions of the main deflection magnetic field produced by the vertical deflection coil 13 and the auxiliary magnetic field produced by the auxiliary coil 18. K Effects of the Invention As described above, the present invention provides an auxiliary coil on the back side of the deflection yoke and on the electron gun side, so that the auxiliary coil generates a magnetic field that causes deflection in the opposite direction to the pre-deflection caused by the leakage magnetic field. A vertical deflection current is applied to the auxiliary coil, and the magnetic saturation characteristics of the auxiliary coil's core are adjusted so that the core of the auxiliary coil becomes magnetically saturated with the vertical deflection current when the electron beam swings vertically to an intermediate position. It is. Therefore, by performing pre-deflection in the vertical direction using an auxiliary coil and changing the amount of pre-deflection by the magnetic saturation of the core, it is possible to improve the convergence in the intermediate portion. Furthermore, by simply adding an auxiliary coil wound around the core, it becomes possible to dynamically correct the convergence in the intermediate region without using a special correction current.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of the main part of a CRT according to an embodiment of the present invention, FIG. 2 is a front view showing an auxiliary coil of the same CRT, FIG. 3 is a drive circuit diagram of the auxiliary coil, and FIG. 4 is a convergence diagram. FIG. 5 is a front view showing the pattern, FIG. 5 is a graph of magnetic saturation characteristics of the auxiliary coil, and FIG. 6 is a graph showing misconvergence. Also, the names of the main parts in the drawings are as shown. 10 ・ 11 ・ 12 ・ 13 ・ 15 ・ 18 ・ 19 ・ 20 ・ 21 ・ 22 ・ ・CRT ・Deflection yoke ・Horizontal deflection coil ・Vertical deflection coil ・Electron gun ・Auxiliary coil ・Core ・Magnetic field ・Vertical deflection magnetic field ・Vertical deflection circuit

Claims (1)

[Claims] 1. A CR comprising a horizontal deflection coil and a vertical deflection coil;
In the deflection yoke that is attached from the funnel part to the neck part of the T, an auxiliary coil is provided on the back side of the deflection yoke and on the electron gun side, and the magnetic field that causes the deflection in the opposite direction to the pre-deflection due to the leakage magnetic field is A vertical deflection current is passed through the auxiliary coil so as to be generated by the auxiliary coil, the magnetic saturation characteristics of the core of the auxiliary coil are adjusted, and the vertical deflection current is applied to the auxiliary coil when the electron beam swings to an intermediate position in the vertical direction. A CRT deflection yoke characterized in that the core is magnetically saturated.