JPS5946739A - Deflection yoke - Google Patents

Abstract

PURPOSE:To correct the variation of the horizontal trapezoidal distortion and horizontal linearity generated since a projected optical axis is inclined for a screen without using an electric distortion correction circuit by providing an asymmetrical jumper coil for the vertical central line of a deflection yoke. CONSTITUTION:One conductor of jumper coils 17a and 17b is arranged on a horizontal deflection coil 11 and the other conductor is arranged near a vertical central axis 16 in which the horizontal deflection coil 11 does not exist. When the right semi-surface of a CRT for projection is deflected, current flows in the horizontal deflection coil 11 and the magnetic field 18 that is symmetrical to the vertical central line 16 and horizontal central line 15 is generated. At the same time, inverse induced current iS flows in jumper coils 17a and 17b arranged on the horizontal deflection coil 11 and an asymmetrical magnetic field 19 is generated for the vertical central line 16 by the jumper coils 17a and 17b. The sum of magnetic fields 18 and 19 forms a magnetic field 20 that differs in the curvature of right and left magnetic force lines and their density for the vertical central line 16.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a deflection yoke used in a projection television set.

In general, a projection television device using a projection tube (hereinafter referred to as a projection CRT) has a red color (R) as shown in FIG.
Three CRTs project light in the three primary colors of green (G) and blue (B).
xl? , xG, and IB from different positions and mix the three primary colors of light on the screen 4 to obtain a color image. Red and blue il! l
Even if the image is rectangular, the projection CRTll? , IB
And Lettuce 2 is also IL in 2B? The projection optical axis 3/(,
Since 3B is horizontally located at a certain angle θ with respect to the screen 4, the image of the image 1 on the screen 4 is as shown in Fig. 2. These image distortions, along with the lascro G caused by the green projection CR 7' located in the center, cause a difference in image distortion, resulting in color misalignment (hereinafter referred to as misconvergence). Therefore, in order to increase the misconvergence, the image on the red projection CRfxR should be shaped like a trapezoid by going to the top and bottom horizontal lines to the bottom b, as shown by the solid line f in Figure 3. II, JR (hereinafter referred to as horizontal trapezoidal distortion) is formed 1-1 left and right kfF, 赳 (with Rastuff C, 7LL)
e interval 11. The conventional method for this purpose is to form a difference in l* (hereinafter referred to as a change in horizontal linearity) and to cancel out the image plane caused by projection onto the screen 4.
The image It' on the projection CRT is distorted in advance by a method using a dedicated frost and air circuit, and the electrical distortion is canceled out by canceling out the above-mentioned horizontal trapezoidal distortion and change in horizontal linearity. It was meant to be corrected. The electrical circuit for this purpose is not only complicated, but also requires a sub-deflection yoke 8 in addition to the deflection yoke 5, as shown in FIG. It is not economical to pass a current, and it also has the drawback of being unstable due to electrical fluctuations, which worsens misconvergence and reduces image quality, so a high degree of stability is required. Met. Note that the horizontal deflection coil 11 and vertical deflection coil 13 of the conventional deflection yoke are shown in (, b) in FIG.
and the horizontal center of the deflection yoke #!, as shown in (,C). The deflection magnetic field formed by the deflection yoke also has symmetry with respect to the center line Q16. The disadvantages of the conventional technology described above are that a dedicated electrical distortion correction circuit is used to correct horizontal keystone distortion and changes in horizontal linearity that occur due to the projection optical axis being aligned with the screen. It is an object of the present invention to provide a deflection yoke that can sufficiently correct or reduce the degree of correction without using it.

In order to achieve the above object, the present invention includes a short-circuited coil asymmetrical with respect to the vertical center line in the deflection yoke to generate a magnetic field that forms the deflection magnetic field asymmetrically. This creates changes in horizontal trapezoidal distortion and horizontal linearity, which are offset and corrected on the screen.

Hereinafter, the present invention will be explained with reference to a deflection yoke shown in the drawings.

As mentioned above, in order to correct horizontal keystone distortion and changes in horizontal linearity of the image reproduced on the screen 4,
There is a method of canceling the distortion by forming an image having distortions in opposite directions vertically and horizontally on the projection CRT in advance and projecting this image onto the screen 4. Hereinafter, means for forming a change in horizontal trapezoidal distortion and horizontal straightness in the image reproduced on the phosphor surface of the projection CKT will be explained for the red projection CRTIR shown in FIG. 1.

Incidentally, FIG. 3 shows the shape of an image that needs to be formed on the fluorescent surface of a projection CRT. Further, FIG. 4 shows a schematic configuration diagram of a conventional correction method.

FIG. 5 shows an embodiment of a deflection yoke 50 according to the present invention.
Short-circuit coil 1 phase α operating together with horizontal deflection coil 11
, 1f b. In the figure, one conductor of the short-circuit coil is placed on the horizontal deflection coil 11, and the other conductor is placed near the vertical central axis 16 where the horizontal deflection coil 11 is not present. When deflecting the right half of the projection CRT, currents t and H flow through the horizontal deflection coil 11 in the directions shown in FIG. A magnetic field having a shape symmetrical with respect to the center line 15 of the direction is generated. At the same time, 17Vs is applied to the short circuit coil 17 placed on the horizontal deflection coil 11.
The current ay'! is in the opposite direction to the current in. # Current is flows, and short circuit coil 17α, 1FIA causes (h
), an asymmetrical magnetic field is generated with respect to the central layer 16 in the vertical direction. The sum of the magnetic fields indicated by 0 and <h> in FIG. 6 becomes a magnetic field 18 in which the curvature of the lines of magnetic force and the density of the lines of magnetic force differ on the left and right sides of the vertical center line 16, as shown by <C) VC in the same figure. As shown in Figure 1, the magnetic field on the right side is stronger than the magnetic field on the left side, and as shown in Figure 1, the raster 7 produces a change in horizontal linearity in the desired direction (zt>1), and - force horizontal trapezoidal distortion in the desired direction. is in the opposite direction.

Next, FIG. 8 shows another embodiment of the deflection yoke according to the present invention. In the same figure, the shorting coil 7 that operates together with the vertical deflection coil 13 includes a conductor arranged asymmetrically with respect to the vertical center m16 on the vertical deflection coil 13, and an electron gun side 20 and a fluorescent surface side 21 of the conductor. It is formed from circumferential conductors that connect the two. Further, the circumferential conductors are connected to form a closed circuit surrounding the central axis 18 of the deflection yoke. When the upper half of the projection CRT is deflected, a current IV flows in the vertical deflection coil unit 3 in the direction shown in (h) of FIG. A magnetic field having a shape symmetrical with respect to the center line 15 of the direction is generated. At the same time, an electromotive force #, ip in the opposite direction to the current IY flows through the short-circuit coil 17 disposed on the vertical deflection coil 13, and the short-circuit coil 1
As shown in FIG. 9(h), a magnetic field is generated which is asymmetrical with respect to the vertical center line 16. The sum of the magnetic fields shown in (a,) and (h) in Figure 9 is as shown in (C) in the same figure.
As shown in , the magnetic field 18 is asymmetrical with respect to the vertical center line 16, and the magnetic field on the right side is stronger than the magnetic field on the left side. Therefore, as shown in FIG. 10, the raster tld produces a horizontal trapezoidal distortion in the desired direction, and the vertical lines c, 7d, and e become arched in the opposite direction to the X axis.

On the other hand, the magnetic field B2 formed by the circumferential current of the short-circuited coil 17 shown in FIG. 8 is a component in the length direction of the deflection yoke as shown in FIG. The Lorentz force F, which acts as a vector product with V, acts in the direction of counterclockwise rotation when it is deflected toward the upper half of the projection CRT, and acts in the direction of clockwise rotation when it is deflected toward the lower half of the projection CRT. Therefore, the shape change of the raster 1 due to the magnetic field generated by the current in the circumferential direction of the short-circuit coil l'7 causes horizontal trapezoidal distortion in the desired direction, as shown in FIG. At the same time, it becomes a vertical line C9γd,'y shape.

Therefore, the overall effect of the short circuit coil 17 shown in FIG. 8 is equal to the sum of the shape changes of the raster shown in FIGS. 10 and 12, and as shown in FIG. 13,
a horizontal trapezoidal distortion in the desired direction, and a vertical line raster lc,
ld. , rye can form a linear raster.

In addition, short-circuit coils 1γa and 1 shown in FIGS. 5 and 8
By using 7J and l'/ in combination, the desired raster in the horizontal trapezoid shown in Fig. 3 and in the same direction as the change in horizontal linearity can be obtained as the sum of the changes in the shape of the raster shown in Figs. 7 and 13. shape can be obtained.

A short-circuit coil 17 shown in FIGS. 5 and 8 can be easily manufactured by connecting the conductor wire to the winding L7 and the beginning and end of the winding. However, as shown in FIG. 14, a conductive flat plate 19 is By cutting into the desired shape 20 and press processing, 1
A short circuit coil 17 corresponding to a turn may be formed and used.

As shown in FIG. 15, another embodiment according to the present invention, some of the conductors of the short-circuit coil 11 disposed on the vertical deflection coil 13 are connected not only to the inner diameter side 22 of the vertical deflection coil 13 but also to the outer diameter side 22 of the vertical deflection coil 13. You can also place it on side 23. In this case, the leakage magnetic field on the outer diameter side of the vertical deflection coil 13 contributes to the generation of an induced electromotive force that causes η to flow and Is to flow through the short-circuited coil F.

In the above explanation, the deflection yoke used for the red projection CRT 1R was explained, but the structure of the deflection yoke used for the blue projection CRT 1B is used for the red projection CRTIR. It is sufficient to make it symmetrical with respect to the vertical center line of the deflection yoke.

The present invention is constructed as described above,
By sufficiently correcting the horizontal keystone distortion and changes in horizontal linearity that cause misconvergence on the screen, or by reducing the amount of correction, the convergence circuit and sub-deflection yoke can be eliminated or simplified. It is possible to obtain economical and stable images.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a conventional projection type color television device, Fig. 2 is a pattern diagram showing changes in horizontal trapezoidal shape and horizontal linearity of an image projected on a screen, and Fig. 3 is a pattern diagram showing changes in horizontal linearity of an image projected on a screen. FIG. 4(a) is a pattern diagram showing the shape of an image that needs to be formed on the screen of a projection CRT, and FIG. ) is a front view of a conventional horizontal deflection coil, FIG. 4(C) is a front view of a conventional vertical coil, and FIG. Front view, Figure 6 (α)
is a diagram of the magnetic field created by the horizontal deflection coil, Figure 6 (A) is a diagram of the magnetic field generated by the short-circuited coil in Figure 5, and Figure 6 (←) is the diagram of the magnetic field created by the short-circuited coil in Figure 6.
FIG. 7 is a pattern diagram showing the shape of the image formed by all the configurations in FIG. 5; FIG. Figures showing the vertical deflection coil, lS, and coil of the deflection yoke; (α) is a plan view of ld; (i is a front view as viewed from arrow A in figure (α); and Figure 9 (α) is a diagram of the magnetic field created by the vertical deflection coil. , Fig. 9 (/1) ij: Explanatory diagram showing the magnetic field generated by the conductor of the short-circuited coil placed on the vertical deflection coil in Fig. 8, Fig. 9 (C) is (α). (5) In Fig. The composite diagram of the magnetic field shown in Figure 10 is similar to Figure 9 (
Shape diagram of the image formed by the magnetic field shown in C), 1st
1- is an explanatory diagram showing the magnetic field generated by the conductor of the short-circuited coil in the circumferential portion of FIG. 8 and the force received by the electron beam; FIG. Fig. 12 is a pattern diagram showing the shape of the image formed by the magnetic field shown in Fig. 11, Fig. 13 is a state diagram when the lower half of the projection CRT is deflected. mud 8
A pattern diagram showing the shape of an image formed by all the configurations shown in the figure, FIG. 14 is an explanatory diagram of a method for manufacturing a short circuit coil according to an embodiment of the present invention, and FIG. 15 is a deflection yoke according to another embodiment of the present invention. FIG. 3 is a diagram showing a vertical deflection coil and a short-circuit coil in FIG. 1 IG...To CRT 2 for projection 2 2G...To lens 3 543G...Projection optical axis 4...To screen 5 5G, 5...Deflection yoke 6G, 646G, 7 ．． F α, F b, F C, 7 beams...image (raster) 8...sub-deflection yoke 9...electron gun lO...electron beam 11...horizontal deflection coil 12...separator 13 ...Vertical deflection coil 14 °゛core 5 ...Horizontal center line 16 ・
・Vertical center line 1 1 h, l ・ Short circuit coil 18 ・ Magnetic field 19 ・ Conductive flat plate 20 ・
... Electron gun side 21 ... Fluorescent side 22 ... Inner diameter side 23 ... Outer diameter side (1
7) O 7 evil blade (0-)
(Shin/, 9 Oq figure (o-) (F)) ;t10 Maro/31 ￥1

Claims (1)

[Claims] In a projection television device that includes a projection tube and a screen and projects an image reproduced on the fluorescent surface of the projection tube obliquely onto the screen, the deflection yoke used in the projection tube includes: A deflection yoke comprising a short-circuit coil disposed asymmetrically with respect to a vertical centerline of the deflection yoke to form a deflection magnetic field asymmetrically with respect to the centerline.