JP2940080B2 - Deflection yoke - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a deflection yoke for a cathode ray tube.

[Summary of the Invention] A deflection yoke according to the present invention is a deflection yoke in which a pair of auxiliary coils for changing the inductance balance of a horizontal deflection coil are connected to the horizontal deflection coil in order to correct misconvergence due to a magnetic field imbalance of the pair of horizontal deflection coils. A yoke, in which both auxiliary coils are magnetically coupled so that the coupling coefficient is positive, and this auxiliary coil is
The auxiliary coil is provided near the T-neck portion, and the leakage magnetic field of the auxiliary coil deflects the beam before horizontal and vertical deflection, so that raster distortion can be corrected.

[Prior Art] As a video signal source input to a television receiver, not only a video signal photographed by an imaging tube but also a CC
There are video signals captured by a D (solid-state imaging device) camera and digitized video signals such as computer graphics.

[Problems to be Solved by the Invention] However, as is well known, an image obtained by a CCD camera, computer graphics, or the like has no vertical deflection operation component in each horizontal line scan.
If you monitor on a CRT, raster distortion will occur.

For example, as schematically shown in FIG. 6, as shown in FIG. 6 (a), the image captured by the image pickup tube is scanned by the electron beam in an oblique direction. As shown in FIG. 2B, there is no raster distortion, but if a scan for capturing or generating a video signal by a CCD camera, computer graphics, or the like is shown in correspondence with the case of an image pickup tube, As shown in FIG.
If this is monitored by a CRT that scans in an oblique direction, the image will be distorted as shown in FIG.

Such raster distortion (hereinafter, this raster distortion will be described
Raster distortion caused by digitized video signals) is particularly noticeable in the case of large-screen CRT monitor displays.
It is a problem.

[Means for Solving the Problems] In view of such problems, the present invention has a very simple configuration and configures a deflection yoke so that raster distortion due to a digitized video signal can be eliminated. It is.

That is, in a deflection yoke provided with a pair of auxiliary coils connected to each horizontal deflection coil in order to change the inductance balance of the pair of horizontal deflection coils, the pair of auxiliary coils are magnetically coupled so that the coupling coefficient between them becomes positive. At the same time, the auxiliary coil is provided near the CRT neck and at a position where the leakage magnetic field of the auxiliary coil can deflect the beam before horizontal and vertical deflection.

[Operation] A pair of auxiliary coils can differentially change the inductance of each coil by inserting and extracting a common core from the coil, and balance the inductance of a pair of horizontal deflection coils connected in series to each other. Although the auxiliary coils are magnetically coupled to each other so that the coupling coefficient is positive, the sum of the leakage magnetic fluxes from both the auxiliary coils is substantially constant even when the core is adjusted.
That is, the leakage magnetic flux is generated stably with respect to the supplied current amount regardless of the inductance balance adjustment position by the core.

Therefore, if the auxiliary coil is provided near the CRT neck,
Along with the original operation for adjusting the inductance balance, the leakage magnetic flux generated with the supplied current can be used to correct the raster distortion by the digitized video signal.

Embodiment FIG. 1 is a side view of a deflection yoke showing one embodiment of the present invention. The deflection yoke 1 has a pair of vertical deflection coils LV ₁ and LV ₂ formed in a toroidal shape, and a pair of horizontal deflection coils LH ₁ and LH ₂ formed in a black shape. The vertical deflection coils LV ₁ and LV ₂ are provided around the cylindrical frame 10,
The electron beam is vertically scanned by 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 generate a magnetic field when a horizontal deflection current is applied to scan the electron beam horizontally.

Each horizontal deflection coil LH ₁ , LH ₂ has the same number of turns,
If the mounting position is shifted due to manufacturing variations, the vertical balance of the generated magnetic field is lost, and misconvergence occurs. Therefore, a pair of auxiliary coils 2 and 3 are provided to correct the magnetic field imbalance and prevent misconvergence.

The auxiliary coils 2 and 3 are connected to one terminal 2a and 3a as shown in FIG.
Is 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. Here, the horizontal deflection current is supplied to the common terminal 8 of the horizontal deflection coils LH ₁ and LH ₂ and the auxiliary coils 2 and 3.
To the common connection terminal 5.

As shown in FIG. 3, a common core 4 is inserted into each of the auxiliary coils 2, 3, and when the core 4 is moved in the left-right direction in the figure, the inductance of each of the auxiliary coils 2, 3 becomes differential. Change. Therefore, since the horizontal deflection current flowing through the pair of horizontal deflection coils LH ₁ and LH ₂ can be slightly changed, the imbalance of the magnetic field generated by the horizontal deflection coils LH ₁ and LH ₂ is corrected and misconvergence is corrected. can do.

Incidentally, when it flows horizontal deflection current to the auxiliary coil 2, each coil 2, 3 flux [Phi _1, but to generate a [Phi _2, the auxiliary coils 2 and 3, the magnetic flux [Phi _1, [Phi ₂ is in Figure 2 As shown, the winding direction is determined so as to pass through the core 4 in the same direction. That is, the coupling coefficient of the auxiliary coils 2 and 3 is positive.

In this case, when the misconvergence is corrected by moving the core 4 as described above, the magnetic flux of one auxiliary coil increases and the magnetic flux of the other auxiliary coil decreases. However, since these auxiliary coils have a positive coupling coefficient, the sum Φ ₁ + Φ ₂ of the magnetic flux by each auxiliary coil is always constant.

In this embodiment, as can be seen from FIG. 1, the auxiliary coils 2 and 3 are located behind the horizontal deflection coil (on the side of the electron gun).
And is attached near the neck N indicated by a dashed line.

Then, as shown in FIG. 4, leakage magnetic fluxes Φ _A and Φ _B are generated at the neck N, and the electron beam before being horizontally deflected is deflected in a predetermined direction.
Winding direction of the auxiliary coil 2 as described above is set so that the magnetic flux directions due to the coils coincide, further, according to the direction of flow of the horizontal deflection current I _H, the winding direction so as to have a predetermined flux direction Is set.

That is, the auxiliary coils 2 and 3 and the horizontal deflection coils LH ₁ and LH ₂
In the case where the horizontal deflection current I _H is supplied during this time, R, G, B in FIG.
During the period when the electron beam is horizontally deflected in the _HA direction by the horizontal deflection coils LH ₁ and LH ₂ , the magnetic flux Φ is generated by the auxiliary coils 2 and 3.
Electron beam _{because A} is formed is deflected in the A direction, is the flux [Phi _A is formed by the auxiliary coil 2 during a period to be horizontally deflected to H _B direction by a flat deflection coil LH _1, LH ₂ electrons The beam is deflected in the B direction.

By deflecting the electron beam before horizontal deflection by the leakage magnetic fluxes Φ _A and Φ _{B in} this manner, it is possible to correct the raster distortion due to the digitized video signal as shown by the dotted line in FIG. At this time, even if the core 4 is moved to adjust the inductance of the horizontal deflection coils LH ₁ and LH ₂ ,
As described above, since the sum of the leakage magnetic flux does not change, the operation of correcting the raster distortion by the digitized video signal is not affected.

[Effects of the Invention] As described above, in the deflection yoke of the present invention, each auxiliary coil for changing the inductance balance of the horizontal deflection coil is magnetically coupled so that the coupling coefficient becomes positive, and this is coupled to the vicinity of the CRT neck. By providing the position, it is possible to very easily correct the raster distortion by the digitized video signal by the leakage magnetic field of the auxiliary coil without requiring a special circuit for the raster distortion correction by the digitized video signal. .

[Brief description of the drawings]

FIG. 1 is a side view of one embodiment of a deflection yoke of the present invention, FIG. 2 is a connection diagram of each coil of this embodiment, FIG. 3 is an explanatory diagram of an auxiliary coil of this embodiment, and FIG. FIG. 5 is an explanatory diagram of a magnetic flux leakage due to the auxiliary coil of the embodiment, FIG. 5 is a diagram illustrating a state in which raster distortion due to a digitized video signal is corrected, and FIGS. FIG. 1 is a deflection yoke, 2 and 3 are auxiliary coils, 4 is a core, LH ₁ and LH ₂
Indicates a horizontal deflection coil, and N indicates a CRT neck.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01J 29/46-29/82

Claims (1)

(57) [Claims] 1. A deflection yoke provided with a pair of auxiliary coils connected to each horizontal deflection coil for changing the inductance balance of the pair of horizontal deflection coils, wherein the pair of auxiliary coils have a positive coupling coefficient. Wherein the auxiliary coils are magnetically coupled to each other, and the auxiliary coil is provided in the vicinity of a CRT neck portion, so that a raster distortion can be corrected by a leakage magnetic field of the auxiliary coil.