JPH0410173B2 - - Google Patents

Description

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

In general, a projection television device using a projection tube (hereinafter referred to as CRT) consists of a projection CRT 1, a lens 2, a screen 4, and a
Consists of etc. In such projection television equipment, as shown in Figure 1,
If the projection optical axis 3 consisting of the CRT 1 and lens 2 is perpendicular to the screen 4, the projection CRT 1
The image is linearly expanded as it is and displayed on screen 4.
If the image on the projection CRT 1 is rectangular, the image reproduced on the screen 4 will also appear as an accurate rectangle as shown by the solid line 5 in FIG.

However, as shown in Figure 2, the projection CRT
A projection optical axis 3 consisting of a lens 1 and a lens 2 is a screen 4.
Even if the image reproduced on the projection CRT 1 is a correct rectangle when it is tilted in the horizontal direction by a certain angle θ with respect to a, the image reproduced on the screen 4a is shown by the solid line 6 in FIG. This results in an image having such horizontal trapezoidal distortion as well as a change in horizontal linearity such that the left side deflection amount 6a and the right side deflection amount 6b in the horizontal direction are different. In addition, when the screen 4b is a part of a spherical surface as shown by the broken line in FIG. become.

In order to correct horizontal keystone distortion, bow distortion, and changes in horizontal linearity of the image reproduced on the screen 4b, conventionally, the image produced on the projection CRT is electrically distorted in advance by a distortion correction circuit. This is corrected by canceling out the electrical distortion and the horizontal trapezoidal distortion, bow distortion, and change in horizontal linearity.

However, the electric circuit for correcting this distortion is not only complicated, but also has the drawback of being unstable with respect to electrical changes. In particular, as shown in Figure 4, the three primary colors of light of red (R), green (G), and blue (B) are projected from separate positions and the three primary colors of light are mixed on the screen 4 to create a color image. If you are trying to get
As shown in FIG. 5, the horizontal keystone distortion (horizontal line 6R) and bow distortion (vertical line 7R) of the red image on the surface of the screen 4, and the horizontal keystone distortion (horizontal line 6B) and bow distortion (vertical line 7R) of the blue image. 7B) is in the opposite direction. Also, the change in horizontal linearity of the red image is that the left side deflection amount 6a-R in the horizontal direction is the right side deflection amount 6b.
-R, and the change in horizontal linearity of the blue image occurs in the direction in which the right side deflection amount 6b-B in the opposite horizontal direction is larger than the left side deflection amount 6a-B. occurs in Therefore, a misconvergence (color shift) occurs between the green image 5G and the green image 5G that is reproduced in a substantially rectangular shape indicated by a broken line. In this case, the electrical correction circuit becomes more complicated, and as shown in FIG.
It is necessary to provide a distortion correction current to this sub-deflection yoke 9 separately. Adjustment of the conventional projection television apparatus is thus extremely difficult. In this case, electrical fluctuations worsen misconvergence and degrade image quality, so the correction circuit is required to have a high degree of stability.

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to sufficiently correct or reduce the misconvergence reproduced on the screen due to horizontal trapezoidal distortion, bowing distortion, or horizontal linearity variation of the raster; The object of the present invention is to provide a deflection yoke having performance that makes it possible to eliminate or simplify an electrical correction circuit.

As mentioned above, in order to correct the horizontal keystone distortion that occurs in the image reproduced on the screen and the bow distortion that occurs in the vertical line raster at the center of the screen, the present invention takes into account that the image is inverted by the lens.
When looking at the image on the CRT's fluorescent surface from the electron gun side,
It is necessary to form on the fluorescent surface of the CRT in advance an image having a distortion in the same direction as the distortion occurring in the image reproduced on the screen to offset the distortion occurring in the image reproduced on the screen.

Therefore, in the present invention, in each of the screen side cross section and the electron gun side cross section in the direction perpendicular to the central axis of the deflection yoke, the winding of the vertical deflection coil is located on the left side with respect to the center line in the vertical axis direction of the screen side cross section. The angle and the winding angle of the vertical deflection coil on the right side are different, and the winding angle of the vertical deflection coil on the left side and the winding angle of the vertical deflection coil on the right side are made different with respect to the center line in the vertical axis direction of the cross section on the electron gun side. In the cross section on the screen side, the winding angle of the vertical deflection coil on one side of the left or right side is larger than the winding angle of the vertical deflection coil on the other side, and in the cross section on the electron gun side, The winding angle of the vertical deflection coil on the other side is greater than the winding angle of the vertical deflection coil on one side. A deflection yoke is constituted by a horizontal deflection coil wound so that the left and right sides are asymmetrical. This forms an image on the fluorescent surface of the CRT that has a distortion that offsets the distortion that occurs in the image reproduced on the screen.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a deflection yoke for a projection television apparatus, which illustrate the present invention in the drawings, will be described.

The means for forming horizontal trapezoidal distortion on the image reproduced on the fluorescent surface of the projection CRT and bow distortion on the vertical line raster of the image is as shown in Figure 4 below, using a CRT1R from the right side and a blue CRT1B from the left side. A red CRT1R in a projection television apparatus for projection will be described.

Furthermore, in the following explanation, all images on the fluorescent surface of the CRT will be explained as seen from the electron gun side.

FIG. 7 shows a raster with horizontal trapezoidal distortion and bow-shaped distortion that is required to be formed on the fluorescent surface of the red projection CRT1R in order to obtain a rectangular raster on the projection screen surface, and the horizontal line 10 is a horizontal trapezoid. The vertical lines 11 also represent bow-shaped distortions.

FIG. 8 shows a perspective view of the vertical deflection coil according to the present invention, and FIG. 9 shows a front view of the vertical deflection coil 13 used in the deflection yoke according to the present invention.

In the electron gun side end face of the vertical deflection coil 13 according to the present invention shown in FIGS. 8 and 9, the winding angle α 1 on the left side with respect to the center line 14 in the vertical axis direction is the winding angle α ₁ on the right side with respect to the center line 14 in the vertical axis direction. Since it is smaller than β ₁ , the winding angle on the left side with respect to the centerline 14 is smaller than the winding angle on the right side. On the other hand, on the end surface of the vertical deflection coil 13 on the screen side, the winding angle α ₂ on the left side with respect to the center line 14 is equal to the winding angle β ₂ on the right side.
, so the winding angle on the left side with respect to the centerline 14 is larger than the winding angle on the right side. In this way, regarding the winding angle of the vertical deflection coil 13, the magnitude relationship between the left and right winding angles of the vertical deflection coil 13 is as follows.
The relationship between the electron gun side and the screen side of 3 is reversed, and the wires are wound diagonally with respect to the central axis O of the deflection yoke 8.

The shape of the raster reproduced on the CRT fluorescent surface when the vertical deflection coil is configured in this manner will be explained. In the vertical deflection coil 13 of the present invention shown in FIGS. 8 and 9, the shape of the magnetic lines of force 15a in a cross section on the electron gun side in the direction perpendicular to the central axis of the deflection yoke is shown in FIG. 10, and the shape of the magnetic lines of force 15b in a cross section on the screen side The shape is shown in FIG. 1st
As shown in FIGS. 0 and 11, the strength of the vertical deflection magnetic field in the vertical deflection coil 13 according to the present invention is determined by The strength and the strength on the right reverse as you move towards the screen,
The strength on the left side will be stronger than the strength on the right side.

First, the effect on horizontal line rasters at the top and bottom of the screen will be explained.

The electron beam that reaches the corner of the raster formed on the CRT fluorescent surface is deflected both horizontally and vertically. Vertical deflection coil 13 according to the present invention
Due to the vertical deflection magnetic field generated by the yoke 8, the strength of the vertical deflection applied to the electron beam reaching the left corner of the screen and the electron beam reaching the right corner of the screen can be adjusted in a direction perpendicular to the central axis O of the deflection yoke 8. Considering the cross section of the vertical deflection coil, in the cross section of the vertical deflection coil on the side closer to the electron gun, the position of the electron beam reaching the left corner of the screen and the position of the electron beam reaching the right corner of the screen are both located at the deflection yoke. Since the electron beam is near the central axis O, the strength of the vertical deflection applied to the electron beam reaching the left corner of the screen is greater than the strength of the vertical deflection applied to the electron beam reaching the right corner of the screen. It's small, but the difference is very small.

Furthermore, as the electron beam advances toward the screen, the position of the electron beam moves away from the central axis O of the deflection yoke 8, so that in the cross section of the deflection coil on the side closer to the screen, it is located at the left corner of the screen. The strength of the vertical deflection applied to the electron beam reaching the screen is greater than the strength of the vertical deflection applied to the electron beam reaching the right corner of the screen, and the difference between them is also large.

On the other hand, since the electron beam that reaches the vertical line at the center of the raster screen formed on the CRT fluorescent surface is deflected only in the vertical direction, the vertical deflection magnetic field created by the vertical deflection coil according to the present invention causes this electric beam to Since the direction of the deflection force applied to is the direction of the arrow shown in each figure of FIG. 10 and FIG. 11, the effect of the winding distribution state in the cross section on the electron gun side and the winding distribution in the cross section on the screen side The state effects almost cancel each other out. Therefore, the raster shape appearing on the fluorescent surface of the CRT is such that the left side of the horizontal line raster at the top and bottom of the screen is wider than the right side, as shown in FIG. 12.

Next, the effect on the vertical line raster at the center of the screen will be explained. Regarding the vertical line raster at the center of the screen, the relationship between the position of the center of gravity of the winding in the cross section on the electron gun side and the position of the center of gravity of the winding in the cross section on the screen side is adjusted, and the center of gravity is shifted to the right as a whole. By configuring this, as shown in FIG. 13, the horizontal line raster 10 at the top and bottom of the screen is similar to that shown in FIG. 12, but the vertical line raster 11 at the center of the screen can form an arcuate distortion with the right side curved. .

In this way, by using the vertical deflection coil 13 according to the present invention shown in FIG.
A raster having a horizontal trapezoidal distortion and an arcuate distortion as shown in FIG. 7 can be formed on the fluorescent surface. As a result, on the projection screen surface of a projection television device, horizontal keystone distortion occurs when the projection optical axis is tilted with respect to the screen, and horizontal keystone distortion occurs when the screen is part of a curved surface. Since both of the arcuate distortions of the two parts can be canceled out at the same time and a rectangular image as shown in FIG. 14 can be obtained, misconvergence on the screen caused by the above distortions can be corrected.

In addition to the above-mentioned distortion, misconvergence on the screen can also be caused by changes in horizontal linearity as described below. This means that when the projection optical axis is tilted horizontally with respect to the screen, the image on the screen surface has the length of the horizontal line raster 6 at the center of the screen as shown in FIG. 3 or 14. When looking at this, a change in horizontal linearity occurs such that the deflection amount 6a on the left side of the horizontal direction and the amount of deflection 6b on the right side in the horizontal direction are different from the vertical line raster 7 in the center of the screen, and this only occurs with the vertical deflection coil. Since it is not possible to correct this by using a horizontal coil, which will be explained below.

Figure 15 shows the red projection CRT1R shown in Figure 4.
2 is a front view of a horizontal deflection coil 16 that constitutes a deflection yoke used in the present invention. In a cross section perpendicular to the central axis of the deflection yoke, the winding density (the number of windings per unit angle) is everywhere where there are windings. However, on the left side of the center line 14 in the vertical axis direction, the number of turns is at a winding angle α both above and below the center line 17 in the horizontal axis direction, whereas on the right side of the center line 14 in the vertical axis direction, the number of turns is is wound at a winding angle α with a gap of angle θ on both the upper and lower sides. In this horizontal deflection coil, there are more windings near the center line in the horizontal axis direction on the left side with respect to the center line 14 in the vertical axis direction, so the strength of horizontal deflection is greater than on the right side. As shown in Figure 16a
As for the raster shape on the CRT screen, regarding the length of the screen horizontal line raster 10, the length of the line segment 10a on the left side of the vertical line 11 can be made longer than the length of the line segment 10b on the right side. Therefore, by combining the horizontal deflection coil 16 and the vertical deflection coil 13 according to the present invention, by combining FIG. 7 and FIG. has an arcuate distortion curved to the right, and regarding the screen top and bottom horizontal line raster 10, the left side is wider than the right side, and the left side has a horizontal trapezoid shape that extends horizontally more than the right side. can be formed. As a result, on the projection screen surface of the projection television device, the projection optical axis is tilted horizontally with respect to the screen, and the screen is a part of a curved surface, so that the projection optical axis is tilted horizontally, and the screen is a part of a curved surface. All geometric distortions are almost completely canceled out and the third
Since a good rectangular raster 5 as shown in the figure can be obtained, screen-like misconvergence can be corrected by the deflection yoke alone.

Figure 17a, b, and c show the configuration of the deflection yoke used in combination with CRT1B, 1G, and 1R that emit light in the three primary colors of blue, green, and red, and the fluorescent surface of the CRT in which the deflection yoke is used. The top shows the shape of the raster that will be played. As shown in FIG. 17a, the vertical deflection coils 13B and 13R are wound symmetrically, and as shown in FIG. 17b, the horizontal deflection coils 13B and 16R are also wound symmetrically. It's wrapped. Vertical deflection coil 13G,
The horizontal deflection coil 16G is the same as that used conventionally. And the first
As shown in Figure 7c, the vertical deflection coil 13B
The horizontal lines 10B of the raster reproduced on the fluorescent surface of the CRT using the horizontal deflection coil 16B have a shape that spreads toward the right, and the vertical lines 11B have an arcuate shape that is concave toward the left. Vertical deflection coil 1
CRT using 3R and horizontal deflection coil 16R
The horizontal lines 10R of the raster reproduced on the fluorescent surface have a shape that spreads toward the left, and the vertical lines 11R have a concave arch shape toward the right. In addition, 13G of vertical coils and 16G of horizontal deflection coils were used.
Raster horizontal line 10 reproduced on the fluorescent surface of CRT
G and the vertical line 11G are the same as the conventional one.

Another example of means for correcting misconvergence due to changes in horizontal linearity using a deflection yoke using a vertical deflection coil according to the present invention will be described below with reference to the red CRT1R shown in FIG.

As shown in FIG. 18, the deflection yoke 8 and the electron gun 1
A beam bender (permanent magnet) 20 is installed between the deflection yoke 8 and the deflection yoke 8, and the electron beam is eccentrically leftward as shown at 18a in FIG. 18 when no current flows through the deflection yoke 8. In the cross section of the horizontal deflection coil perpendicular to the central axis 22 of the deflection yoke, the horizontal deflection magnetic field is always stronger at the left and right ends of the horizontal axis than near the center of the deflection coil. If the bender is eccentric, the amount of horizontal deflection of the electron beam 18b that reaches the left end of the CRT's phosphor surface as shown by the broken line in FIG. 18 is the amount of horizontal deflection of the electron beam 18c that reaches the right end of the CRT's phosphor surface becomes larger than

Therefore, in this case, even if the horizontal deflection coil is a symmetrical winding as in the past, misconvergence due to changes in horizontal linearity can be corrected, and as shown in FIG. If the electron beam is decentered in the direction shown by the arrow 21 with respect to the vertical deflection coil 13 involved, the CRT
The raster shape on the fluorescent surface can be any desired raster shape similar to that shown in FIG. 16b.

If the amount of eccentricity of the electron beam by the beam bender is large, the horizontal deflection coil 16 is made asymmetrical, as shown in FIG.
Even if the orientation is reversed from that shown in FIG. 15, a desired raster shape as shown in FIG. 20b can be obtained. In this case, the horizontal deflection coil 16 works to reduce the effect of correction due to eccentricity of the electron beam by the beam bender in terms of correction of the horizontal linearity of the raster on the screen, but it works in the direction of correcting the horizontal trapezoidal distortion of the raster on the screen. , which works to increase the effect of correction by the vertical deflection coil according to the present invention.

FIG. 21A shows a case where a deflection yoke that combines the above-mentioned horizontal deflection coil and the vertical deflection coil according to the present invention is used in an actual color projection television set, and the respective vertical deflection coils are shown in FIG. FIG. 21b shows the direction of eccentricity of the electron beam by each horizontal deflection coil and each beam bender, and FIG. 21c shows the shape of the raster formed on the fluorescent surface of each CRT. In FIG. 21b, arrows 21B and 21R indicate the direction in which the electron beam is deflected by the beam bender.

In FIG. 21, horizontal deflection coils 16B and 16
Although R is placed in the opposite position to that in Fig. 17,
The beam bender 20 causes the electron beam to move in the direction of the arrow 21.
Since the light is deflected in the directions B and 21R, the raster formed on the fluorescent surface of the CRT has the same shape as shown in FIG. 17c, and therefore the misconvergence of the raster is corrected.

As explained above, according to the present invention, the horizontal trapezoidal distortion, bow distortion, and horizontal linearity change of raster, which are causes of misconvergence that occurs in images reproduced on a screen, can be sufficiently corrected or the amount of correction can be reduced. By doing so, it is possible to eliminate or simplify the misconvergence correction circuit and the sub-deflection yoke, and it is possible to provide a deflection yoke for a projection television apparatus that can reproduce stable images.

[Brief explanation of drawings]

Figures 1 and 2 are schematic diagrams showing the relationship between the screen and the projection device in a projection television device, and Figure 3 shows the horizontal keystone distortion, bow distortion, and horizontal linearity of the projected image reproduced on the screen surface. 4 is a schematic diagram showing a color projection device, and FIG. 5 is a pattern diagram showing a misconvergence pattern that occurs in an image reproduced on the screen of the color projection device shown in FIG. 4. , 6th
The figure is a front view showing the configuration of the projection CRT, deflection yoke, and sub-deflection yoke. Figure 7 is for red projection to obtain a rectangular raster on the screen surface.
FIG. 8 is a perspective view of the vertical deflection coil according to the present invention; FIG. 9 is a front view of the vertical deflection coil according to the present invention; 10 and 11 are pattern diagrams showing the shapes of magnetic lines of force in a cross section on the electron gun side and a cross section on the screen side in the direction perpendicular to the central axis of the deflection yoke, respectively, for the vertical deflection coil according to the present invention, and FIG. Figures 13 and 14 are pattern diagrams of raster shapes formed on the fluorescent surface of a CRT by an electron beam deflected by a vertical deflection coil according to the present invention, and Figure 15 is a diagram according to the present invention. A front view of the horizontal deflection coil used in combination with the vertical deflection coil, FIG. 16a is a pattern showing the shape of the raster formed by the electron beam deflected by the horizontal deflection coil shown in FIG. 15. Figure 16b
17 is a pattern diagram showing the shape of a raster formed on a fluorescent surface by the electron beam deflected by the vertical deflection coil according to the present invention and the horizontal deflection coil shown in FIG. A front view of each deflection coil when the vertical deflection coil according to the invention and the horizontal deflection coil shown in FIG. 15 are used in a color projection device, and FIG. FIG. 3 is a pattern diagram showing a raster shape reproduced on a light surface. FIG. 18 is a schematic diagram showing the eccentricity of the electron beam by the beam bender and the horizontal deflection of the electron beam by the deflection yoke. FIG. 19 is a schematic diagram showing the eccentricity of the electron beam by the beam bender and the vertical FIG. 20a is a diagram showing the relationship between the orientation of the deflection coil, and FIG. 20b is a front view of a horizontal deflection coil used in combination with the vertical deflection coil according to the present invention, in which the electric beam is decentered by a beam bender. 21A and 21B are pattern diagrams showing the raster shape formed on the fluorescent surface by the electron beam deflected by the horizontal deflection coil and the vertical coil, and FIGS. A vertical deflection coil according to the present invention,
FIG. 21c is a front view of each of the vertical and horizontal deflection coils when used in a color projection device in combination with a horizontal deflection coil, and is a pattern diagram showing the raster shape formed on the fluorescent surface of the CRT. . 12... Core, 13, 13B, 13G, 13R
...Vertical coil, 16, 16B, 16G, 16R
...Horizontal coil.

Claims (1)

[Claims] 1. In a deflection yoke for a projection television device that is used by being attached to the projection tube of a projection television device that projects a reproduced image on the fluorescent surface of the projection tube from an oblique direction to the projection screen surface, A vertical deflection coil wound around a core constituting the deflection yoke is wound obliquely to the center axis of the deflection yoke, and a cross section perpendicular to the center axis on the screen side of the deflection yoke and the electron gun side of the deflection yoke The angular distribution of the windings of the vertical deflection coil in the cross section perpendicular to the central axis is different on the left and right sides with respect to the center line in the vertical axis direction of both cross sections, and the center line in the horizontal axis direction of both cross sections is different. The angular distribution of the windings of the vertical deflection coil is symmetric with respect to
and the winding angle of the vertical deflection coil on the left side and the winding angle of the right vertical deflection coil are different with respect to the center line in the vertical axis direction of the cross section on the screen side, and with respect to the center line in the vertical axis direction of the cross section on the electron gun side. The winding angle of the vertical deflection coil on the left side and the winding angle of the vertical deflection coil on the right side are different, and in the cross section on the screen side, the winding angle of the vertical deflection coil on one side of the left side or the right side is different from the winding angle of the vertical deflection coil on the other side. The winding angle of the vertical deflection coil on the other side is larger than the winding angle of the vertical deflection coil on one side in the cross section on the electron gun side. Deflection yoke for projection television equipment.