KR0137112Y1 - Focus magnet for controlling electronic beam - Google Patents

Abstract

The present invention relates to an electron focusing focus magnet disposed between an image gun and an electron gun of a cathode ray tube, particularly a high-quality projection type receiving tube, and used for electron beam control, and a short circuit of an auxiliary coil due to excessive current applied to the auxiliary coil in the prior art. And at least one static coil and two or more dynamic coils arranged coaxially with the other bobbins inside the two permanent magnets disposed so as to face different magnetic poles through the bobbins to prevent overheating. By configuring the auxiliary coil to minimize the difference in resolution between the center portion and the periphery of the water pipe screen, it is possible to extend the life and reduce the power consumption.

Description

Focus magnet for electron beam control

1 is a longitudinal sectional view showing a focus magnet for electron beam control according to an embodiment of the present invention;

2 is a longitudinal sectional view showing a focus magnet for controlling a general electron beam.

* Explanation of symbols for main parts of the drawings

1, 10: Focus magnet 9: Permanent magnet

12, 17: bobbin 21: static coil

23, 25: dynamic coil

The present invention relates to a focus magnet for controlling an electron beam, and more particularly, an electron beam disposed between an image gun and an electron gun of a cathode ray tube, particularly a high quality projection type receiving tube, to improve peripheral dynamic focus on a screen, thereby improving product resolution. The present invention relates to an electron focusing focus magnet used for control.

Projection-type water tube used in high-definition television of projection type shows the received image as an enlarged image on the screen. In the water tube having a relatively small optical surface, the electron beam emitted from the electron gun can emit light obtained by leisure of the phosphor. Through an optical lens placed close to the front of the boss and projected again on a relatively large screen, a clear and enlarged image is obtained.

Conventionally, an electrostatic type is used as a device for converging an electron beam of a water tube, and a magnetic field type is used for special tubes of X-ray tubes, magnetrons, and traveling wave tubes. However, in recent years, high resolution televisions and the like have been required to have a high resolution. As one of the magnetic field methods, the electromagnet system has a large size and a drawback that requires a power source. Therefore, permanent magnets have emerged.

A conventionally known focus magnet used for electron beam focusing using such a magnetic field method is shown in FIG.

In the figure, the focus magnet 1 is provided on the outer periphery of the neck portion 5 between the video screen (not shown) of the water pipe and the electron gun.

The focus magnet 1 opposes two hollow-cylindrical permanent magnets 9 that are magnetized in the axial direction through the bobbin 11 having a cross section substantially cross-shaped to form a magnetic pole in the cross section with different magnetic poles. Similarly disposed on the coaxial, the auxiliary coils 13, 15 for adjusting the central magnetic field are arranged on the inner circumference of the permanent magnet 9, and on the outer circumference of the permanent magnet 9 A yoke 19 surrounding the component is provided to form a ring-shaped assembly.

The bobbin 11 interposed between the permanent magnet 9 and the auxiliary coils 13 and 15 may be divided into a plane perpendicular to the axis to facilitate assembly.

The auxiliary coils 13 and 15 may include a static coil 13 for adjusting the magnetic field generated by the permanent magnet 9 at the center of the screen where the electron beam is formed, and a dynamic coil 15 for adjusting the focus of the outer periphery of the screen. Consists of That is, since the permanent magnet 9 does not have a wide margin so as to completely complement the characteristics of the electron gun, the permanent magnet 9 is generated in the permanent magnet 9 using the auxiliary coils 13 and 15. This is for achieving accurate focus of the electron beam 7 reaching the screen by adding and decreasing magnetic flux density.

Accordingly, the electron beam 7 emitted from the cathode 3 of the electron gun adjusts the magnetic field generated by the permanent magnet 9 as the excitation current of the auxiliary coils 13 and 15 to form the electron lens 1. Electrons are focused and deflected by a deflection coil (not shown) to form an image on the screen of the receiving tube.

A problem associated with the above-described focusing magnet for controlling the electron beam is that it is difficult to achieve accurate focus together at the center and the periphery of the screen on which the electron beam emitted from the cathode of the electron gun is imaged.

The conventional focus magnet maintains proper focus by adding or subtracting a magnetic field of a permanent magnet as an auxiliary coil. The focus magnet has a design value and a position that varies depending on the electrostatic part of the electron gun, so that the optimal electron beam focusing can be achieved during assembly. In order to achieve this, a predetermined current is applied to the auxiliary coil, that is, the dynamic coil or the static coil, thereby adding or decreasing a magnetic field of the permanent magnet.

However, the auxiliary coil has a different inductance value of the coil according to the material and the amount of applied current. When the current flows above the threshold to achieve the just focus of the electron beam, the coil is short-circuited and cannot use the entire focus magnet.

In other words, a current of 250 mA or more is applied to a conventional dynamic coil or a static coil in order to focus the electron beam by adjusting a magnetic field of a permanent magnet. At this time, the inductance value of the coil is not matched with the frequency current and the coil is shorted. The phenomenon is often occurring.

In addition, when excessive current flows in the auxiliary coil as described above, a large burden is generated on the driving circuit of the focus magnet, and power consumption is also increased.

In order to solve the above problems of the prior art, the present invention is mounted on the neck portion between the image screen of the water pipe and the electron gun, the focus magnet for controlling the electron beam emitted from the cathode of the electron gun, via a bobbin A secondary coil comprising two or more dynamic coils arranged coaxially with at least one static coil via two bobbins inside two permanent magnets arranged to face each other with different magnetic poles. .

The auxiliary coil has at least one dynamic coil for pre-focusing the electron beam which proceeds to the static coil.

The focus magnet of the present invention is provided with a plurality of dynamic coils having at least one pre-focusing function, which is intended to solve the problem that the auxiliary coil is shorted by preventing excessive current from being applied to the auxiliary coil.

The plurality of dynamic coils disposed before and after the static coil include at least one dynamic coil for pre-focusing the electron beams directed to the static coil, thereby reducing the overload of the static coil and at the center of the screen. It is easy to maintain just focus.

In addition, since the dynamic coil is composed of a plurality, it is a matter of course that the conventional overload is reduced by half even if not described, and the electron beam focus on the periphery of the screen is also advantageous.

Therefore, the focus magnet of the present invention is able to achieve accurate focus together at the center and periphery of the screen where the electron beam emitted from the cathode of the electron gun is imaged, and there is no burden on the driving circuit of the focus magnet because no overcurrent is applied to the auxiliary coil. In addition, power consumption can be reduced.

EXAMPLE

1 is a longitudinal cross-sectional view showing a state in which the electron beam control focus magnet of the present invention is mounted on the neck portion of the water pipe. In order to avoid duplication of description of the drawings, the same parts as in FIG.

The focus magnet 10 for electron beam focusing according to the present invention has the same shape as that of the hollow park cylindrical permanent magnet 9 disposed coaxially so as to face different magnetic poles through the bobbin 12. On the inner circumferential side, auxiliary coils for center magnetic field adjustment are provided via bobbins 17, respectively.

The auxiliary coil coaxially applies a static coil 21 for adjusting the focus of the center of the screen by adding or subtracting a magnetic field generated by the permanent magnet 9 and a dynamic coil 23, 25 for adjusting the focus of the outer periphery of the screen. It is placed in a phase.

That is, the focus magnet 10 of the present invention includes two or more dynamic coils for adjusting the focus at the periphery of the screen, and in the embodiment of the present invention, two dynamic coils 23 and 25 are installed. An Example is shown.

The dynamic coils 23 and 25 have at least one dynamic coil 23 having a function of pre-focusing an electron beam directed to the static coil 21 in order to reduce excessive current applied to the static coil 21. Equipped with.

As can be seen from the drawing, the arrangement of the auxiliary coils includes the dynamic coil 23, the static coil 21, and the dynamic coil 25 in order of adjusting the focus of the center of the screen. It is preferable to arrange in the middle. This is because the dynamic coil 23 pre-focuss the electron beam traveling to the static coil 21, thereby reducing the overcurrent applied to the static coil 21 to short-circuit the coil. Will be prevented.

Referring to the operation of the focus magnet for electron beam control of the present invention configured as described above in more detail as follows.

The electron beam 7 emitted from the cathode 3 of the electron gun is focused while passing through the focus magnet 10 of the electron focusing method, and the electron beam passing through the focus magnet 10 is a permanent magnet 9. The static coil 21 and the dynamic coil 25 which are pre-focused while passing through the dynamic coil 23 which forms the electronic lens by adjusting the magnetic field generated by the magnetic field, and add or subtract the magnetic field of the permanent magnet 9 again. Through this electron focusing is achieved.

The electron beam is then deflected by a convergence yoke and deflection coil (not shown) mounted on the neck of the receiver tube to form the desired image on the screen.

As described above, the focus magnet of the present invention is provided with at least two dynamic coils in an auxiliary coil for magnetic field adjustment installed through a bobbin on an inner circumferential side of a permanent magnet, which is conventionally used as a dynamic coil and a static coil, respectively. Since excessive current is applied to the configured auxiliary coil, the auxiliary coil has a benefit of solving the short-circuit problem.

In addition, the dynamic coil disposed before the static coil reduces the overload that has been applied to the static coil by pre-focusing the electron beam directed to the static coil, and easily maintains the just focus at the center of the screen. Since the dynamic coil is configured in plural numbers, the conventional overload is reduced by half as described above, and the electron beam focus on the screen periphery is also advantageous.

This can suppress excessive heat generation of the auxiliary coil due to the conventional overload. Therefore, the focus magnet of the present invention can minimize the difference in resolution by forming an accurate focus together at the center and the periphery of the screen where the electron beam emitted from the cathode of the electron gun is formed. In addition, since the overcurrent is not applied to the auxiliary coil, power consumption is reduced and the long life can be maintained because it does not burden the driving circuit of the focus magnet.

Claims (3)

In the focus magnet mounted on the neck portion between the image screen of the water pipe and the electron gun to control the electron beam emitted from the cathode of the electron gun by adjusting the magnetic field generated in the permanent magnet by using the excitation current of the auxiliary coil, the auxiliary coil The focus magnet for electron beam control, characterized in that it comprises two or more dynamic coils (23, 25) and at least one static coil (21) arranged coaxially. 2. The focus magnet for electron beam control according to claim 1, wherein the auxiliary coil comprises at least one dynamic coil (23) for pre-focusing. 2. Focus magnet for electron beam control according to claim 1, characterized in that the static coil (21) is arranged between the dynamic coils (23, 25).