JPH0793110B2 - Deflection yoke of cathode ray tube - Google Patents

Description

TECHNICAL FIELD The present invention relates to a deflection yoke of a cathode ray tube.

[Outline of Invention]

A pair of auxiliary coils provided to adjust the inductance balance of a pair of horizontal deflection coils are magnetically coupled with a positive coupling coefficient so that the total number of leakage magnetic fluxes is kept constant even when the inductance is adjusted. At the same time, the auxiliary deflection coil is magnetically coupled to the vertical deflection coil to cancel the horizontal deflection pulse leaked to the vertical deflection coil side so as to reduce crosstalk and thereby reduce the crosstalk.

[Conventional technology]

In a cathode ray tube, beam deflection is performed by a deflection yoke including a pair of horizontal deflection coils and a pair of vertical deflection coils. If, for example, the core is displaced due to manufacturing variations, the magnetic field balance of the pair of horizontal deflection coils is disrupted, and misconvergence occurs. For example, as shown in FIG. 7, a convergence error called cross-miscon occurs in which the scanning lines of the R beam and the scanning lines of the B beam intersect on the vertical axis.

Therefore, as shown in FIG. 8, a pair of horizontal deflection coils LH ₁ , L
Horizontal deflection coils by connecting auxiliary coils La and Lb in series to H _2.
The inductance of LH ₁ and LH ₂ is adjusted to balance the generated magnetic field. This type of auxiliary coil is, for example,
No. 61-53846.

The two auxiliary coils La and Lb have a common core c (for example, a rod core) as shown in FIG. 9, and by inserting and removing the core c from the coil, the inductances of both coils are differentially changed, The horizontal deflection coils LH ₁ and LH ₂ are balanced in inductance.

[Problems to be solved by the invention]

A magnetic flux is generated by the horizontal deflection current from the auxiliary coils La and Lb. When this magnetic flux interlinks with the vertical deflection coil, crosstalk of the horizontal deflection pulse is induced in the vertical deflection system. Therefore, the mounting direction of the auxiliary coil is made to be the direction orthogonal to the magnetic flux of the vertical deflection coil, or the auxiliary coil is mounted so as to be separated from the vertical deflection coil so as to minimize the coupling between them.

However, since the adjustment direction of the auxiliary coil is limited when mounted in this manner, the workability of adjusting the inductance is deteriorated and a mounting space problem occurs.

Crosstalk is caused not only by the auxiliary coil as described above but also by stray capacitance coupling and magnetic coupling between the horizontal deflection coil and the vertical deflection coil. The one caused by the stray capacitance is not so large, but in the case of the high definition CRT, the influence becomes large. As the total amount of crosstalk increases, the interlace characteristic, that is, the uniformity of the spacing between the odd field lines and the even field lines, deteriorates.

Further, as shown in FIG. 9, each of the horizontal deflection coils LH ₁ and LH ₂ is arranged so that the coupling coefficient between the auxiliary coils La and Lb becomes negative.
It is proposed to connect to. In this case, if the core c is located at the center, the strengths of the magnetic fluxes generated in the coils La and Lb are the same, and the directions thereof are opposite to each other. Therefore, since these magnetic fluxes cancel each other out, the leakage magnetic flux from the auxiliary coil can be made extremely small to reduce the crosstalk amount.

However, when the core c is moved to correct the misconvergence, the magnetic fluxes generated in the coils La and Lb become unbalanced, and there is a drawback that the crosstalk sharply increases.

The present invention has been made in view of the above problems, and an object thereof is to reduce crosstalk between a horizontal deflection coil and a vertical deflection coil.

[Means for solving problems]

The deflection yoke 1 of the present invention includes a pair of toroidal vertical deflection coils LV ₁ and LV ₂ and a pair of hull type horizontal deflection coils L.
H ₁ and LH ₂ and a pair of auxiliary coils 2 and 3 connected to each horizontal deflection coil in order to change the inductance balance of the pair of horizontal deflection coils LH ₁ and LH ₂ .

The pair of auxiliary coils as the coupling coefficient is positive with be magnetically coupled to each other, the auxiliary in order to bind to the leakage flux phi _1, the phi ₂ vertical deflection coil LV _1, LV ₂ of the auxiliary coils 2 and 3 Coil 2 and 3 are the above vertical deflection coils LV ₁ and L
It is located near V ₂ .

[Action]

Leakage fluxes φ ₁ and φ ₂ of the auxiliary coils 2 and 3 are vertical deflection coils.
If the position of the auxiliary coil is determined so as to cancel the horizontal deflection pulse leaked to the vertical deflection coil side by combining with LV ₁ and LV ₂ , the total crosstalk amount is reduced. Since the auxiliary coils 2 and 3 are magnetically coupled so that the coupling coefficient is positive, the total leakage magnetic flux φ ₁ + φ ₂ is substantially constant even if the coil core 4 is adjusted. Therefore the horizontal deflection coil L
Even if the core 4 is moved to adjust the current balance of H ₁ and LH ₂ , it does not deviate from the cancellation point.

〔Example〕

FIG. 1 is a side view of a deflection yoke showing an embodiment of the present invention, and FIG. 2 is a rear view. This deflection yoke 1
Is a pair of vertical deflection coils L formed in a toroidal shape
V ₁ and LV ₂ and a pair of horizontal deflection coils L formed in a paddle shape
It has H ₁ and LH ₂ . The vertical deflection coils LV ₁ and LV ₂ are provided on the peripheral surface of the cylindrical frame 10 and vertically scan the electron beam with a magnetic field generated when a vertical deflection current is applied.
The horizontal deflection coils LH ₁ and LH ₂ are provided above and below the inside of the vertical deflection coils LV ₁ and LV ₂ , and when a horizontal deflection current is applied, a magnetic field is generated to horizontally scan the electron beam.

Even if the number of turns of the horizontal deflection coils LH ₁ and LH ₂ is the same, if the mounting positions of the horizontal deflection coils LH ₁ and LH ₂ deviate due to manufacturing variations, the vertical balance of the generated magnetic field is lost and misconvergence occurs. A pair of auxiliary coils 2 and 3 are attached to the peripheral surface of the deflection yoke 1 so as to correct the up-and-down balance of the horizontal deflection coils LH ₁ and LH ₂ and prevent misconvergence caused thereby.

These auxiliary coils 2 and 3 have one terminal as shown in FIG.
2a and 3a are connected to the terminals 6 and 7 of the horizontal deflection coils LH ₁ and LH ₂ , and the other terminals 2b and 3b are commonly connected. The horizontal deflection current is passed between the common connection terminal 8 of the horizontal deflection coils LH ₁ and LH ₂ and the common connection terminal 5 of the auxiliary coils 2 and 3.

The auxiliary coils 2 and 3 are closely attached in the winding direction, and the common core 4 is inserted. When this core 4 is moved in the left-right direction in FIG. 3, the inductance of each auxiliary coil 2, 3 changes differentially. Therefore, a pair of horizontal deflection coils LH ₁ , LH ₂
It is possible to slightly change the horizontal deflection currents flowing in each of the horizontal deflection currents, and it is possible to correct the misconvergence due to the loss of the magnetic field balance generated in the horizontal deflection coils LH ₁ and LH ₂ .

When the horizontal deflection current flows through the auxiliary coils 2 and 3, magnetic fluxes φ ₁ and φ ₂ are generated in the coils 2 and 3, respectively. Each coil 2, so that these magnetic fluxes φ ₁ , φ ₂ pass through the core 4 in the same direction,
The winding direction of 3 is defined. That is, the coupling coefficient of the auxiliary coils 2 and 3 is positive.

When the core 4 is moved to correct the misconvergence as described above, the magnetic flux of the one auxiliary coil 2 or 3 increases and the magnetic flux of the other auxiliary coil 2 or 3 decreases. However, since these auxiliary coils have a positive coupling coefficient, the sum of the magnetic fluxes φ ₁ + φ ₂ is always constant.

In this embodiment, this constant magnetic flux φ ₁ + φ ₂ is used to cancel the horizontal deflection current leaked to the vertical deflection coil side. That is, the auxiliary coils 2 and 3 are fixed on the support plate 11 provided on the cylindrical frame 10 of the deflection yoke, and are arranged close to the vertical deflection coils LV ₁ and LV ₂ . The auxiliary coil 2,
The winding direction of 3, that is, the longitudinal direction of the core 4 is the tangential direction of concentric circles around the beam axis. Therefore, the auxiliary coils 2 and 3 interlink with the leakage magnetic fluxes generated from the vertical deflection coils LV ₁ and LV ₂ concentrically around the beam axis. On the contrary, the leakage fluxes from the auxiliary coils 2 and 3 are vertical deflection coils LV ₁ and LV ₂
And the two are magnetically coupled. Further, the coupling direction is a direction for canceling the above-mentioned crosstalk.

FIG. 4 shows the waveform of the vertical deflection current on which the crosstalk component of the horizontal deflection current is superimposed, and FIGS. 5A and 5B are partial enlarged views. When the amplitude e ₁ of the horizontal deflection current component ih leaking to the vertical deflection current iv was actually measured with a certain picture tube, it was about 1 Vp-p. Here, by changing the positions of the auxiliary coils 2 and 3 and appropriately changing the degree of coupling with the vertical deflection coils LV ₁ and LV ₂ , the maximum amplitude e ₂ of the horizontal deflection current component ih is shown in FIG. As shown in [B], about 0.
The cancellation point was halved to 5Vp-p.

Since the coupling coefficients of the auxiliary coils 2 and 3 are positive as described above, the core 4 is moved to move the horizontal deflection coil L
Even if the misconvergence correction of H ₁ and LH ₂ is performed, the total magnetic flux φ ₁ + φ ₂ does not change. Therefore, the above cancellation points do not change as they are.

FIG. 6 shows a voltage waveform of a coil terminal connected to the drive circuit of the vertical deflection coil. The crosstalk component is also superimposed on the vertical deflection voltage ev as indicated by the dotted line eh. Although the amplitude of the vertical deflection voltage ev has a margin with respect to the power supply voltage E as shown in FIG. 6, when the crosstalk voltage component (horizontal deflection pulse) eh is superposed, it exceeds the power supply voltage by that amount. The characteristics of the driving circuit may be deteriorated because the clipping occurs. For example, the width of the blanking pulse BLK widens, and the deflection linearity at the upper end of the screen deteriorates.

When the crosstalk is canceled and reduced as in the present embodiment, the voltage component eh also becomes small, and the above-mentioned inconvenience does not occur. Therefore, it becomes possible to lower the power supply voltage while satisfying a certain output swing.
The power loss of is reduced. Further, even for a large-sized tube that requires a large vertical output voltage, it becomes possible to use the same vertical drive IC and power supply voltage as the medium-sized tube.

〔The invention's effect〕

As described above, according to the present invention, the pair of auxiliary coils for correcting the inductance balance of the pair of horizontal deflection coils are coupled with a positive coupling coefficient, and the leakage flux thereof is coupled with the vertical deflection coil. By selecting the coupling direction and coupling degree, the horizontal deflection pulse component leaked to the vertical deflection coil side can be canceled and the total amount of crosstalk can be reduced. Further, even if the inductance of the horizontal deflection coil is corrected, the total number of leakage magnetic fluxes from the auxiliary coil does not change, so that the cancellation point does not shift, and the inductance correction and the crosstalk suppression can be made to function independently of each other. .

[Brief description of drawings]

FIG. 1 is a side view of a deflection yoke showing an embodiment of the present invention,
FIG. 2 is a rear view of the deflection yoke, FIG. 3 is a connection diagram of each coil, FIG. 4 is a waveform diagram of the vertical deflection current showing a state in which the horizontal deflection current leaks, and FIG. 5 is a partial enlargement of the vertical deflection current. FIG. 6A is a diagram showing a state where the amplitude of crosstalk is large, FIG. 6B is a diagram showing a state where the magnetic flux of the auxiliary coil is coupled to reduce the amplitude of crosstalk, and FIG. FIG. 7 is a waveform diagram showing a state in which crosstalk is present on the waveform, FIG. 7 is an explanatory diagram of raster scanning, and FIGS. 8 and 9 show a conventional technique, which is a connection diagram of a horizontal deflection coil and an auxiliary coil. In the reference numerals used in the drawings, 1 ... Deflection yoke 2, 3 ... Auxiliary coil 4 ... Core LV ₁ , LV ₂ ... Vertical deflection coil LH ₁ , LH ₂ ... Horizontal deflection coil.

Claims (1)

[Claims] 1. A pair of toroidal vertical deflection coils, a pair of hull-shaped horizontal deflection coils, and a pair of auxiliary coils connected to each horizontal deflection coil for changing the inductance balance of the pair of horizontal deflection coils. The pair of auxiliary coils are magnetically coupled to each other so that the coupling coefficient is positive, and the auxiliary coil is arranged in the vicinity of the vertical deflection coil to couple the leakage flux of the auxiliary coil to the vertical deflection coil. Deflection yoke of a cathode ray tube.