JPH0492342A - Deflection yoke and horizontal deflection circuit - Google Patents

Abstract

PURPOSE:To suppress a ringing of the current flowing and to a resonance circuit formed of flouting capacities horizontal deflection coils, by adding a magnetic core to a horizontal deflection coil couple, or the like. CONSTITUTION:By adding a magnetic core to the tangent lines 4 and 5 for deflecting current of a deflection yoke 2, or by making the direction of winding of horizontal deflection coils L1 and L2 in the reverse direction, a current flows to floating capacities between the horizontal deflection coils and a CRT, and to a resonance circuit formed of the horizontal deflection coils, in the period of retrace line, and a ringing of the current is suppressed. As a result, a raster ringing can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a deflection yoke and a horizontal deflection circuit that can reduce raster ringing, and is particularly useful when the horizontal deflection frequency is a high frequency of several tens of kHz or more.

[Prior Art] Raster ringing is a phenomenon that produces bright and dark Mlo at the left edge of the screen, as shown in FIG.

In order to solve this raster ringing problem, as shown in FIGS. 6(a) and 6(b), a pair of horizontal deflection coils Ll and L2 connected in parallel are wound around the magnetic core in the same way at the coupling part. Two sub-coils 81. A technique for interposing S2 has been proposed (see Japanese Patent Laid-Open No. 1-184841).

In this prior art, horizontal deflection coils LL and L2 and their surrounding members (especially CR
Stray capacitance CO between (coating of T) and horizontal deflection coil L
Considering that one of the causes of raster ringing is that a resonant current flows through the resonant circuit consisting of L and L2, this resonant current is attenuated by the sub coils S1 and S2.

[Problems to be Solved by the Invention] In the above-mentioned prior art described in JP-A-1-134841, firstly, as shown in FIG. 6(a), the sub coils Sl, S2
When connected, the horizontal deflection coil L2 has the above-mentioned resonance current damping effect, but the horizontal deflection coil L1 has no resonance current damping effect at all, so there is a problem that raster ringing cannot be sufficiently reduced.

Second, as shown in FIG. 6(b), the sub coil Sl.

When S2 is connected, if there is a difference in the current flowing through the horizontal deflection coil LI L2, not only will there be a loss in the horizontal deflection current, but the current difference will saturate the magnetic core, reducing its energy absorption function. There are some problems.

Thirdly, due to the structure, in both cases shown in FIGS. 6(a) and 6(b), the sub-coils Sl, S2 and the magnetic core must be attached to the deflection side, which poses a problem that imposes restrictions on implementation. be.

Therefore, an object of the present invention is to significantly reduce raster ringing effectively for either of a pair of horizontal deflection coils, and without causing any problems even if there is a difference in the deflection current flowing between the horizontal deflection coils. The object of the present invention is to provide a deflection yoke and a horizontal deflection circuit that can be easily implemented.

[Means for Solving the Problems] In a first aspect, the present invention provides a deflection yoke having a horizontal deflection coil pair in which a pair of horizontal deflection coils are connected in parallel, in which a horizontal deflection current is supplied to the horizontal deflection coil pair. A magnetic core is attached to the connection wire for horizontal deflection coil and CR.
Provided is a deflection yoke characterized in that ringing of a current flowing through a resonant circuit formed by a stray capacitance between T and a horizontal deflection coil is suppressed.

In a second aspect, the present invention provides a deflection device characterized in that the winding directions of a pair of horizontal deflection coils connected in parallel are opposite to each other, and the window side of each horizontal deflection coil is set as a low voltage side. Provide a yoke.

In a third aspect, the present invention attaches a magnetic core to the horizontal deflection current output line to suppress stray capacitance between the horizontal deflection coil and the CRT and ringing of the current flowing in the resonant circuit formed by the horizontal deflection coil. A horizontal deflection circuit is provided.

[Operation] A resonant circuit is formed by the stray capacitance between the horizontal deflection coil and the CRT and the horizontal deflection coil. A current flows through this resonant circuit during the retrace period, and the ringing of the current is one cause of raster ringing.

However, in the deflection yoke and horizontal deflection circuit of the present invention, a magnetic core is attached or the winding method of the horizontal deflection coil is devised so that the current flowing from the horizontal deflection coil to the CRT or from the CRT to the horizontal deflection coil during the retrace period is reduced. to suppress ringing.

Therefore, raster linking can be reduced.

Furthermore, in the deflection yoke according to the first aspect of the present invention and the horizontal deflection circuit according to the third aspect, since the magnetic core is attached to the connecting line between the horizontal deflection coil and the horizontal deflection circuit, It is valid.

Further, even if there is a difference in the deflection currents flowing through one horizontal deflection coil, no problem occurs.

Further, in the deflection yoke according to the second aspect of the present invention, the winding directions of the pair of horizontal deflection coils are opposite to each other, and
Since a low voltage is applied to the window side of each horizontal deflection coil, the amount of charge charged to the stray capacitance is reduced, and raster ringing can be controlled.

[Example] The present invention will be further described below with reference to Examples shown in the drawings. Note that this invention is not limited to this.

FIG. 1 is a circuit explanatory diagram showing a deflection yoke 2 according to an embodiment of the present invention, a horizontal output circuit 1 that is a part of a horizontal deflection circuit that supplies a horizontal deflection current to the deflection yoke 2, and a CRT 3. be.

In the horizontal output circuit 1, a switching transistor T is activated by a pulse voltage from a horizontal drive circuit (not shown).
r is driven, and by the action of the damper diode D, the resonant capacitor C1, and the pair of horizontal deflection coils Ll and L2 provided in the deflection yoke 2, the horizontal deflection coils Ll and L2
A sawtooth deflection current is supplied to the In addition, E is a DC power supply,
C2 is a figure-8 correction capacitor, and FBT is a flyback transformer.

In the deflection yoke 2, the connecting wires 4 and 5 between the pair of horizontal deflection coils Ll and L2 connected in parallel and the horizontal output circuit 1 are inserted through a ring-shaped ferrite core 6 and wound once.

Since the ferrite core 6 functions as a common mode choke, it is preferable to use a ferrite core for EMI (electromagnetic interference) prevention.

Graphite conductive films 8a and 8b are formed on the inner and outer surfaces of the CRT 3, and the external conductive film 8a is grounded via the CRT return line 7.

The conductive films 8a and 8b of the CRT 3 and the horizontal deflection coil Ll
, L2 is one of the causes of raster ringing in high frequency CRT display devices.

Note that in this embodiment, the horizontal deflection coil Ll.

The self-inductance of L2 is about 85 μH1 and the horizontal deflection frequency is about 85 kHz.

Figure 3 shows the connecting wire 4 without the ferrite core 6.
, 5 are the results of measuring the current flowing through them in common mode. This current flows from the horizontal deflection coils LL and L2 to the CRT3 via the stray capacitance CO during the first half of the retrace period, and from the CRT3 to the horizontal deflection coils Ll and L2 during the second half, and during the scanning period. It can be seen that ringing occurs at the beginning of the line. This current ringing is
This is the cause of raster ringing on the screen. The frequency of this ringing portion is about several MHz, which is about two orders of magnitude higher than the horizontal deflection frequency.

FIG. 2 shows the results of measuring the current flowing through the connecting wire 4.5 in common mode with the ferrite core 6 provided in the connecting wire 4.5. Compared to FIG. 3, the high frequency ringing portion is damped and significantly reduced. At this time, the raster ringing on the screen was also significantly reduced.

The ferrite core 6 has a large energy absorption effect on the ringing portion having a high frequency in the common mode portion of the current flowing through the connecting wire 4.5. On the other hand, since the directions of the currents are opposite to each other, no effect is exerted on the deflection current.

Therefore, by providing the ferrite core 6, there is no risk of increasing loss in the horizontal deflection circuit, unlike when impedance elements are connected to both ends of the horizontal deflection coils LL and L2. Therefore, raster ringing on the screen is effectively suppressed.

In the above embodiment, the ferrite core 6 is integrally attached to the deflection yoke 2, but it may be integrally attached to the horizontal output circuit 1.

Note that the ferrite core 6 may be provided on the return line 7 of the CRT 3.

On the other hand, the winding directions of the pair of horizontal deflection coils LL and L2 are opposite to each other, and furthermore, each of the horizontal deflection coils LL and L
If the horizontal output circuit 1 is connected to the window side part 2 at a low voltage, the amount of charge charged in the stray capacitance CO will be reduced, and raster ringing will also be reduced. FIG. 4 shows a sectional view of a main part of the horizontal deflection coil L1 having this structure.

A portion C of the horizontal deflection coil L1 on the window W side is a low voltage side, and a portion C on the opposite side to the window W is a high voltage side.

[Effects of the Invention] According to the deflection yoke and horizontal deflection circuit of the present invention, it can be applied effectively to either of a pair of horizontal deflection coils, and there is no problem because there is a difference in the deflection current flowing between the two horizontal deflection coils. , raster ringing can be reduced.

Further, the magnetic core for damping ringing is not limited to being attached to the deflection yoke, but can also be attached to the horizontal deflection circuit.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the circuit configuration of an embodiment of the present invention, Fig. 2 is a waveform diagram of the current measured in common mode with the magnetic core attached to the connection line between the horizontal deflection coil and the horizontal deflection circuit, and Fig. 3. is a waveform diagram of the current measured in common mode with no magnetic core attached to the connection line between the horizontal deflection coil and the horizontal deflection circuit, Figure 4 is a cross-sectional view of the main part of the horizontal deflection coil, and Figure 5 is an explanation showing raster ringing. Figure, Figure 6 (
a) and (b) are explanatory diagrams of conventional raster ringing suppression techniques. (Explanation of symbols) 1...Horizontal output circuit 2...Deflection yoke 3...CRT 4.5...Connection wire 6...Magnetic core LL, L2...Horizontal deflection coil CO...Floating Capacity W: Horizontal deflection coil window.

Claims (1)

[Claims] 1. In a deflection yoke having a horizontal deflection coil pair in which a pair of horizontal deflection coils are connected in parallel, a magnetic core is attached to a connecting wire for supplying a horizontal deflection current to the horizontal deflection coil pair, and a horizontal A deflection yoke is characterized in that ringing of a current flowing through a resonant circuit formed by a stray capacitance between a deflection coil and a CRT and a horizontal deflection coil is suppressed. 2. A deflection yoke characterized in that the winding directions of a pair of horizontal deflection coils connected in parallel are opposite to each other, and the window side of each horizontal deflection coil is set as a low voltage side. 3. A magnetic core is attached to the horizontal deflection current output line to suppress stray capacitance between the horizontal deflection coil and the CRT and ringing of the current flowing through the resonant circuit formed by the horizontal deflection coil. Horizontal deflection circuit.