JPH0261942A - Deflection yoke of cathode-ray tube - Google Patents

Abstract

PURPOSE:To decrease the amount of leakage of the deflecting magnetic field to outside a deflection yoke by installing a shield made from a metal plate having a high magnetic permeability in close constant with the whole circumference of a magnetic core. CONSTITUTION:When deflection current is supplied to a saddle type yoke 1, a deflecting magnetic field is generated on the inside of the yoke 1 and used to deflect an electron beam in a CRT. The deflecting magnetic field is released from inside to the outside and detoured by a core 2. As the core 2 is composed of an upper and a lower part, the magnetic resistance will increase, which together with high frequency loss in the core 2 causes leakage of the magnetic field to outside the core 2. A shield 3 is formed from a metal plate having a high permeability and put in close contact with the whole periphery of the core 2, and the seam 4 of the shield shall be situated 90 deg. rotated from the seam of core 2. This accomplishes decrease of the leaking amount of deflecting magnetic field to outside the deflection yoke.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a deflection yoke for scanning an electron beam of a CRT, and more particularly to a saddle-saddle type deflection yoke that reduces the amount of deflection magnetic field leaking to the outside.

[Conventional technology]

Conventionally, the saddle-saddle type deflection yoke used in CRTs consists of a pair of horizontal yokes and a pair of horizontal yokes for deflecting the electron beam.
It consisted of a pair of vertical yokes and a magnetic core attached to their outer peripheries to form a magnetic path.

[Problem to be solved by the invention]

The conventional deflection yoke described above is constructed as shown in Fig. 3, and the core on the outer periphery of the yoke consists of upper and lower parts as shown in Fig. 4, which are attached closely together. Because the magnetic resistance increases in the core and the high frequency loss of the core is relatively large, it is not possible to completely bypass the magnetic field generated by the deflection yoke inside the core, and the magnetic field is generated outside the core. It had the drawback of leaking. Therefore, conventional CRT displays and televisions using deflection yokes have the disadvantage that they may emit electromagnetic waves exceeding the regulation value.

[Means to solve the problem]

The deflection yoke of the present invention is characterized by having a horizontal and vertical yoke, a core on its outer periphery, and a shield made of a metal plate with high magnetic permeability attached to the entire outer periphery of the core, so that the magnetic field leaking from the core is not radiated outside the deflection yoke. Have (・ru.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a perspective view showing a core portion and a shield portion shown to clarify the structure of the present invention.

When a deflection current is applied to the saddle type yoke, a deflection magnetic field is generated inside the yoke 1 and is used to deflect the electron beam of the CRT. The deflection magnetic field is emitted from the inside to the outside, but is bypassed by the core I. Since the core is composed of two upper and lower parts as shown in FIG. 2, the magnetic field leaks to the outside of the core 1 due to increased magnetic resistance and high frequency loss of the core 1. The shield 1 is made of a metal plate with high magnetic permeability such as permalloy, and functions to shield the magnetic field leaking from the core 1 so as not to radiate it to the outside.

It is effective to attach the shield cap in contact with the core I, and the shielding effect is great if the shield is attached so that the seam of the shield is rotated 90 degrees from the seam of the core I.

[Effects of the Invention] As explained above, the present invention reduces the amount of deflection magnetic field leaking out of the deflection yoke by closely attaching a shield made of a metal plate with high magnetic permeability to the outer periphery of the core of the deflection yoke. This has the effect of reducing electromagnetic wave radiation from CRT displays and televisions.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of the present invention, Fig. 2 is a perspective view showing the shape of the main part of the invention, Fig. 3 is a longitudinal sectional view of a conventional deflection yoke, and Fig. 4 is a portion related to the invention. FIG. 1... Saddle type yoke, 2... Core,
3... Shield, 4... Shield seam. Agent Patent Attorney Uchihara Onji Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A saddle-saddle type CRT deflection yoke characterized by having a shield molded from a high magnetic permeability metal plate closely attached to the entire outer periphery of a magnetic core.