JP2570734Y2 - Focus magnet for electronic lens - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a focus magnet for an electron lens which is used for adjusting the electromagnetic deflection of an electron beam emitted from, for example, a cathode ray tube electron gun.

[0002]

2. Description of the Related Art FIG. 4 is a side sectional view of a main part showing a peripheral structure of a focus magnet for an electronic lens of this type as a conventional example. In FIG. 4, inside the glass bulb neck portion 7 of the cathode ray tube, the anode 8 is controlled by the first and second grids 9a and 9b from the cathode 10.
There is an electron gun mechanism that emits an electron beam B toward
A so-called electron lens that electromagnetically deflects this electron beam B to form an image on a cathode ray tube (not shown)
Many developments have been made. FIG. 4 itself is also a means to be an invention of the applicant. For the electron beam B from the electron gun mechanism, a center yoke 4 made of a cylindrical ferromagnetic material is disposed at the center, and magnets made of the same cylindrical permanent magnets 3a and 3b are fixed to both end surfaces. A static magnetic field for an electron lens is formed. Two types of coils are cascaded and arranged in order from the electron gun side to the cathode ray tube screen while being inscribed on the inner peripheral side and circumscribing the outer peripheral surface of the glass bulb neck portion 7 of the cathode ray tube stem. One of these two types of coils is a static coil 1 composed of a hollow cylindrical coil that applies a direct current and focuses near the center of the picture plane of the cathode ray tube to create an electromagnetic field for initial adjustment. Is a hollow cylindrical dynamic coil 2 that focuses near the periphery of the picture plane of the cathode ray tube and creates an electromagnetic field for distortion correction. A dynamic magnetic field for an electron lens is provided. Permanent magnets 3a and 3b in which these center yokes 4 are sandwiched, and side yokes 5a and 5b made of a disk-shaped ferromagnetic material fixed to the permanent magnets on the outer end surfaces of the dynamic coil and the static coil. By doing so, a focus magnet for an electron lens is configured. In this manner, by adjusting the static and dynamic magnetic fields of the electron lens focus magnet, an appropriate deflection of the electron beam B is performed by the action of the magnetic flux φ.

Further, FIG. 3 developed by the applicant shows a focus magnet for an electron lens (hereinafter referred to as a "prior example") having a configuration shown in a side sectional view of a main part. In the drawings, the same reference numerals represent the same or corresponding members. In this prior example, a dynamic coil and a static coil are each divided into two or more parts, and the divided small dynamic coils and small static coils are connected in series to each other to form the original dynamic coil and static coil. The number of turns of the coil is maintained. This dividing means can easily presume from the arrangement of the static coil and the dynamic coil that there is electromagnetic coupling. However, either of these coils is divided and each of the divided small coils is insulated. By providing the function as a single static coil or a dynamic coil, the equivalent capacitance of those coils is significantly reduced, and as a result, the frequency characteristic of the inductance L of the dynamic coil is far greater than that of the conventional example. This is based on the parallel resonance circuit theory that, for example, in the case of two divisions, it extends to about twice (the peak value extends from 140 KHz of the conventional example to 280 KHz). That is, the capacitance of the coil changes from left to right as indicated by the arrow in FIG. 5, and the frequency characteristic of the parabolic pulsating current flowing through the dynamic coil 2 is extended.

[0004]

However, in this conventional example, however, for example, the outer diameter of the glass bulb neck 7 of the tube stem is 34 mm, the outer diameter of the side yoke is 58 mm, the thickness is 2.3 mm, and the permanent magnet 3a, The outer diameter of 3b is
59mm, thickness 8mm each, static coil 1 has a diameter of 0.
A DC current is passed by winding an enamel wire of 18 mm only 560 times, and the dynamic coil 2 is wound 75 times of an enamel wire of 0.35 mm diameter. The coil current passed through the dynamic coil 2 is shown in FIG. Such a parabolic pulsating parabolic current. Then, as shown, the outermost diameter (3a,
3b) The width of the permanent magnets 3a, 3b and the ring-shaped portions of the coils 1, 2 is set so that the width of 59mm and the innermost diameter (1, 2) of 34mm is split, and each coil is housed in the bobbin 6. .
Under such conditions of the conventional example, the frequency characteristic of the parabolic current of the inductance L of the dynamic coil 2 has a peak value near a frequency of 140 KHz, and the characteristic curve appears remarkably before and after the peak value. The frequency band is at most about 130 KHz. Such narrowing of the used frequency band has been a bottleneck in stepping up image quality and other quality. Then
In the prior example which was made to overcome the difficulties of the conventional example, since the static coil and the dynamic coil have electromagnetic coupling, the static coil driving power supply [DC]
The influence of the impedance level on the dynamic coil affects the value (frequency characteristic) of the inductance L of the dynamic coil, causing a problem that the image quality changes. Here, in order to solve such a problem of the conventional example, the present invention forms a dynamic coil and a static coil into two or more divided windings, and magnetically separates the dynamic coil and the static coil from each other. It is an object of the present invention to provide a focus magnet for an electronic lens provided with means for disposing a blocking yoke for blocking.

[0005]

In order to achieve the above object, the present invention provides a center yoke made of a cylindrical ferromagnetic material at a central portion, and uses a same cylindrical permanent magnet at both end surfaces. A static magnetic field formed by fixing a magnet is provided, inscribed in the inner peripheral side surface, circumscribed and circumscribed to the outer peripheral surface of the CRT stem portion, and arranged in order from the electron gun side to the CRT screen, a direct current is supplied. A static coil consisting of a hollow cylindrical coil that focuses near the center of the CRT screen and creates an electromagnetic field for initial adjustment, and a high-frequency current flows to focus around the CRT screen and create an electromagnetic field for distortion correction A permanent magnet and a static magnet having a dynamic magnetic field formed by a hollow cylindrical coil and having a center yoke sandwiched therebetween. Focusing electron lens having a coil and side yokes made of a disk-shaped ferromagnetic member fixed to the permanent magnets on the outer end face of the dynamic coil
In the magnet, the static coil and the dynamic coil are divided into two or more parts each having the outside of the coil insulated and covered with each other, and each divided coil is connected in series, and the center yoke is substantially centered. Divided into two parts, between each of the two divided center yokes,
A focus magnet for an electron lens, wherein a cut-off yoke for magnetically shutting off between a static coil and a dynamic coil is arranged in the same material and shape as the side yoke.

[0006]

[Effect] It can be easily inferred from the arrangement of the static coil and the dynamic coil that there is electromagnetic coupling. However, either of these coils is divided, and each of the divided small coils is coated with an insulating film. One static
Provide a function as a coil or dynamic coil, the equivalent capacitance of those coils is significantly reduced,
As a result, the frequency characteristic of the inductance L of the dynamic coil is much improved as compared with the conventional example, and a blocking yoke for blocking the electromagnetic coupling between the static coil and the dynamic coil is interposed. Electromagnetic interference between the dynamic coils is reduced, so that the influence of the impedance of the driving power supply of the static coil does not interfere with the dynamic coil.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a block diagram showing a circuit configuration of an embodiment of the present invention. In FIG. 1, center yokes 4a and 4b made of a cylindrical ferromagnetic material are disposed at the center, and magnets 3a and 3 made of the same cylindrical permanent magnet are provided at both end surfaces.
Provide a static magnetic field formed by fixing b. A static coil 1 and a dynamic coil 2 are arranged in order from the electron gun side to the cathode ray tube screen, inscribed in the inner peripheral side surface and circumscribed and circumscribed to the outer peripheral surface of the cathode ray tube stem 7, and stored in the bobbins 6a, 6b. I do. The static coil 1 is divided into three to become small static coils 1a and 1b and further to 1c [in contrast to the previous example of 560 windings, this embodiment has 244 windings × 3 windings]. In addition, each of the small static coils 1a, 1b, and 1c is covered with an insulating member and insulated from each other as if the coils had different functions. 1
a, 1b, and 1c are connected in series and arranged at the same position as in the conventional example. The dynamic coil 2 is also divided into two small dynamic coils 2a and 2b.
In this embodiment, the number of turns of 75 is changed to 39 times x 2 turns].
a and 2b are wrapped with insulating members to insulate each other as if they were coils having different functions, but the two small dynamic coils 2a and 2b are connected in series, Arrange in the same position. At this time, the outer diameter of the glass bulb neck portion 7 of the cathode ray tube portion is 34 mm, the outer diameter of the side yoke is 68 mm, the thickness is 3.0 mm, and the permanent magnets 3a, 3b
Has an outer diameter of 69 mm, a thickness of 10 mm each, and the static coils 1a, 1b, 1c are 244 times enameled wires of 0.18 mm diameter x 3
The dynamic coils 2a and 2b are wound 39 times x 2 enamel wires having a diameter of 0.35 mm. The coil current flowing through the dynamic coils 2a and 2b is shown in FIG. It is a parabolic current of a parabolic pulsating flow as shown. Thus, the dynamic coils 2a, 2b
And the static coils 1a, 1b, 1c are electromagnetically coupled from each other, so that the dynamic coil 2 is divided into two and the small dynamic coils 2a and 2b
In FIG. 5, the capacitance of the coil changes from left to right as shown by an arrow in FIG. 5, and the static coil 1 is similarly divided into three to obtain small static coils 1a, 1b, and 1c. This also means that the capacitance of the coil changes from left to right as indicated by the arrow in FIG. 5, and the parallel resonance frequency characteristics of the parabolic current flowing through the dynamic coils 2a and 2b are extended.

However, as shown in FIG. 2 (a), in the prior art, since the static coil and the dynamic coil have electromagnetic coupling, the static coil drive power supply [DC] depends on the level of the impedance. Of dynamic coil inductance L (frequency characteristics)
By opening or shorting both terminals of the small static coils 1a, 1b, 1c connected in series,
Regarding the L value (milli-Henry mH of the inductance) of the dynamic coil connected in series with the small dynamic coils 2a and 2b, the curve 21 is obtained when both ends of the static coils 1a, 1b and 1c are open. When both terminals are short-circuited, the curve 22 changes and accordingly the image quality changes accordingly. In view of the above, according to the present invention, the center yoke is divided into two substantially at the center portion, and the center yoke 4a, 4b is divided between the center yokes 4a and 4b by the same material and shape as the side yoke. A focusing magnet for an electronic lens, which is provided with a blocking yoke 5c for magnetically blocking between the coil and the dynamic coil. As a result, FIG.
The value of the inductance L of the dynamic coil shown in (b) does not depend on the change of the impedance characteristic of the static coil driving power supply [DC] from the frequency of 1 KHz to 100 KHz. , 1c are open, the curve is 23, and when both terminals are short-circuited, the curve is 24, and there is no change. The impedances of the static coils 1a, 1b, 1c and the dynamic coils 2a, 2b The frequency characteristic of the inductance, which is the L value of the dynamic coil connected in series, is the same in both extremes of open and short, and becomes flat. That is, the static coils 1a, 1b, 1c
Is low, the sensitivity of the dynamic coils 2a and 2b does not decrease due to the impedance of the static coils 1a, 1b and 1c.

[0009]

Thus, according to the present invention, the built-in static coil or both the static coil and the dynamic coil are separately wound to extend the resonance frequency inherent in the coil, thereby increasing the dynamic coil. The frequency characteristics of the dynamic coil can be shifted to the higher frequency side by increasing the frequency of the high-frequency signal flowing through the Magnetically cut off between the two to flatten the frequency characteristics by preventing the dynamic coil from following the change in the impedance of the static coil,
The magnetic circuit of the static coil and the magnetic circuit of the dynamic coil can be approximately separated from each other, reducing the magnetic interference between the two coils. Can be particularly improved.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a configuration of a main part in an embodiment of the present invention.

FIG. 2 is a frequency characteristic diagram showing how the inductance of a dynamic coil is affected by a change in the impedance of a static coil in a prior art and an embodiment of the present invention;

FIG. 3 is a side sectional view showing a configuration of a main part of a prior art example.

FIG. 4 is a side sectional view showing a configuration of a main part in a conventional example.

FIG. 5 is an explanatory diagram of an equivalent electric circuit of the coil dividing means of the present invention.

FIG. 6 is an explanatory diagram of a parabolic current flowing through the dynamic coil of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Static coil 1a Static coil 1b Static coil 1c Static coil 2 Dynamic coil 2a Dynamic coil 2b Dynamic coil 3a Permanent magnet 3b Permanent magnet 4 Center yoke (ferromagnetic material) 4a Center yoke (ferromagnetic Body 4b Center yoke (ferromagnetic material) 5a Side yoke (ferromagnetic material) 5b Side yoke (ferromagnetic material) 5c Shielding yoke (ferromagnetic material) 6 Bobbin (electrical insulator) 6a Bobbin (electricity) 6b Bobbin (electrical insulator) 7 Glass bulb neck 8 Anode 9a First grid 9b Second grid 10 Cathode B Electron beam φ Magnetic flux

Claims (1)

(57) [Scope of request for utility model registration] 1. A static magnetic field formed by fixing a center yoke made of a cylindrical ferromagnetic material at the center and fixing magnets made of the same cylindrical permanent magnet to both end surfaces thereof. Electromagnetic for initial adjustment by flowing DC current and focusing near the center of the CRT screen, inscribed in the inner peripheral side and circumscribed and circumscribed to the outer peripheral surface of the CRT stem in order from the electron gun side to the CRT screen. A dynamic coil formed by a static coil consisting of a hollow cylindrical coil that creates a field, and a dynamic coil consisting of a hollow cylindrical coil that creates an electromagnetic field for correcting distortion by focusing near the CRT screen by applying a high-frequency current A permanent magnet with a magnetic field and a sandwich of these center yokes and permanent magnets on the outer end faces of the static and dynamic coils. A focus magnet for an electron lens having a side yoke made of a disk-shaped ferromagnetic material fixed to a stone, wherein two or more static coils and a dynamic coil are mutually insulated and covered on the outside of the coil. The split yoke is connected in series with each split coil, and the center yoke is split into two parts at almost the center part. A focusing magnet for an electronic lens, wherein a blocking yoke for magnetically blocking between a static coil and a dynamic coil is provided.