JPH07226942A - Convergence correction device - Google Patents

Abstract

PURPOSE:To correct independently mis-convergence of a longitudinal line caused to an upper part and a lower part of a CRT screen. CONSTITUTION:When an upper part of a screen is deflected vertically, a vertical deflection current I inputted to a terminal T1 flows through vertical deflection coils VL1, VL2 and through a diode D1 and the current is branched into shunt currents I1, I2 by a variable resistor R1 and return to a vertical deflection circuit from a terminal T2 through convergence correction coils L1, L1. When a lower part of the screen is deflected vertically, the vertical deflection current I inputted to the terminal T2 is branched into shunt currents I1, I2 flowing through the convergence correction coils L1, L2 and combined at a variable resistor VR2 into the vertical deflection current and return to the vertical deflection circuit from the terminal 1 through a diode D2 and the vertical deflection coils VL1, VL2. A ratio of the shunt currents I1, I2 is independently adjusted by using the variable resistors VR1, VR2 when the upper part of the screen and the lower part of the screen are deflected vertically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection yoke which is used by being attached to an in-line color cathode ray tube (hereinafter referred to as a CRT), and more particularly, a vertical line misconversion occurring at the upper and lower portions of the screen. The present invention relates to a convergence correction device that corrects the presence.

[0002]

CRTs using in-line array beams
In this case, vertical line misconvergence occurs as shown in FIG. 5 at the top and bottom of the screen. Here, the solid line passing through the center of the screen is the R (red) vertical line, and the broken line passing through the center of the screen is B.
(Blue) Vertical line. This is caused by the misalignment between the R beam and the B beam at the upper and lower parts of the screen, which becomes noticeable and deteriorates the image quality.

As a conventional example of the convergence correction device for correcting the misconvergence of the vertical lines, there is known one disclosed in Japanese Patent Laid-Open No. 3-247093. This is because a first diode and an upper side correction coil are connected in series, and a second diode opposite to the first diode and a lower side correction coil are connected in parallel. It is connected in series to the vertical deflection coil, and an impedance element is connected between the connection point of the first diode and the upper side correction coil and the connection point of the second diode and the lower side correction coil.

With such a configuration, when vertically deflecting the upper half of the screen, the first diode is turned on and the vertical deflection current flows through the upper side correction coil, and the lower side correction coil is passed through the impedance element. Part of the vertical deflection current flows. Therefore, the magnitudes of the currents flowing through the upper side correction coil and the lower side correction coil are different, and the vertical line misconvergence generated at the upper part of the screen is corrected by the action of the magnetic fields generated by the respective coils. When vertically deflecting the upper half of the screen, the second diode conducts, and the same operation as described above corrects the vertical line misconvergence that occurs at the bottom of the screen.

[0005]

However, in the above-mentioned prior art, the vertical line misconvergence occurring in the upper and lower portions of the CRT screen cannot be adjusted independently. Therefore, if the vertical line misconvergence occurring at the upper part and the lower part of the screen is different, such misconvergence cannot be sufficiently corrected.

The object of the present invention is to eliminate such problems and to provide C
It is an object of the present invention to provide a convergence correction device capable of independently adjusting the misconvergence of vertical lines generated in the upper part and the lower part of the RT screen.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides at least a pair of diodes, which are connected in opposite directions and are connected in parallel, connected to a vertical deflection coil, and the diode, respectively. It is composed of a variable resistor connected to each of the convergence correction coils to divide a vertical deflection current flowing through the vertical deflection coil.

Further, according to the present invention, a fixed resistor having a predetermined resistance value is connected in series to each of the variable resistors.

Further, according to the present invention, each convergence correction coil is composed of two coils connected in series, and these two coils are provided on the magnetic body.

[0010]

The vertical deflection current is shunted to the respective convergence correction coils by the variable resistors. Depending on the direction in which the vertical deflection current flows, that is, when the upper half of the screen is vertically deflected and when the lower half of the screen is vertically deflected. The variable resistance for shunting the vertical deflection current to the convergence correction coil is different when the deflection is performed. Therefore, it is possible to independently adjust the ratio of the currents flowing in the respective convergence correction coils when vertically deflecting the upper half of the screen and vertically deflecting the lower half of the screen, and therefore, the upper part of the screen is adjusted. Even if the vertical line misconvergence that occurs is different from the vertical line misconvergence that occurs at the top of the screen, they can be corrected independently.

Further, by connecting a fixed resistor in series to the variable resistor, the resistance value of the fixed resistor can be appropriately set and a bias can be added to the correction amount of the misconvergence, whereby the misconvergence of the variable resistor can be suppressed. The center value of the adjustment range can be changed and the optimum value can be set.

Further, two convergence correction coils are provided.
By constructing the coils connected in series, the coils can be provided at two symmetrical positions of the magnetic body, and these coils may be attached to both ends of the magnetic body as already wound.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of a convergence correction apparatus according to the present invention, in which 1 is a convergence yoke drive circuit, VL1 and VL2 are vertical deflection coils, and D1 and D are D1 and D2.
2 is a diode, R1 and R2 are fixed resistors, VR1 and VR
2 is a variable resistor, L1 and L2 are convergence correction coils, T1 and T2 are terminals, P1 is a contact point, I is a vertical deflection current, and I1 and I2 are split currents.

In the figure, terminals T1 and T2 are connected to a vertical deflection circuit (not shown), and vertical deflection coils VL1 and VL2 are connected in series between one terminal T1 and a contact point P1. Between the other terminal T2, a series circuit of a fixed resistor R1 and a convergence correction coil L1 and a series circuit of a fixed resistor R2 and a convergence correction coil L2 are connected in parallel. In addition, fixed resistance R
1, variable resistors VR1 and VR2 are connected in parallel between a connection point of the convergence correction coil L and a connection point of the fixed resistance R2 and the convergence correction coil L2,
A contact point P1 is provided between the variable contact piece of the variable resistor VR1 and the contact point P1.
The diode D1, which is in the forward direction when viewed from the side, is
Between the variable contact piece of R2 and the contact point P1, a diode D2 which is in the opposite direction when viewed from the contact point P1 side is connected.

In such a structure, the vertical deflection current I is supplied from the vertical deflection circuit between the terminals T1 and T2.
Vertically deflecting the upper half area of the CRT screen and CRT
The direction in which the vertical deflection current I flows is opposite to that in the case of vertically deflecting the lower half region of the screen, and when vertically deflecting the upper half region of the CRT screen, the vertical deflection current I is, for example, from the terminal T1 to the terminal T2. In the case of vertically deflecting the lower half area of the CRT screen, the vertical deflection current I
Flows from the terminal T2 toward the terminal T1.

Therefore, the vertical deflection current I is now applied to the terminal T1.
The vertical deflection current I passes through the vertical deflection coils VL1 and VL2, and is divided into the divided currents I1 and I2 by the variable resistor VR1 from the contact point P1 through the diode D1 in the forward direction at this time. These divided currents I1 and I2 respectively flow through the convergence correction coils L1 and L2, and return from the terminal T2 to the vertical deflection circuit.

Here, under the constant condition of VCR (convergence pattern defined by the EIAJ standard) (that is, all conditions such as winding distribution, which are factors that change the amount of convergence that can be defined as VCR, are constant. The vertical line convergence correction (when
This is performed by adjusting R1 to optimize the ratio of the divided currents I1 and I2.

When the vertical deflection current I flows from the terminal T2, the vertical deflection current I is shunted to the convergence correction coils L1 and L2 and flows, and is combined by the variable resistor VR2. These convergence correction coils L1 and L
The ratio of the currents flowing through 2 is optimized by adjusting the variable resistor VR2. The vertical deflection current I synthesized by the variable resistor VR2 is in the forward direction at this time.
It returns to the vertical deflection circuit through the terminal D2 and the vertical deflection coils VL1 and VL2.

The vertical line convergence correction under a constant VCR condition is performed by adjusting the variable resistor VR2 to optimize the ratio of the divided currents I1 and I2.

In this way, the variable resistors VR1 and VR2 are
Is adjusted, the ratio of the amount of current flowing through the convergence correction coils L1 and L2 can be independently optimized when vertically deflecting the upper half of the CRT screen and when deflecting the lower half. .

FIG. 2 is a circuit diagram showing another embodiment of the convergence correction device according to the present invention, in which R3 to R6 are fixed resistors, and the parts corresponding to those in FIG.

In this figure, this embodiment differs from the embodiment shown in FIG. 1 in that fixed resistors R3 and R4 are provided in series with variable resistor VR1 and fixed resistor R2 is provided in series with variable resistor VR2.
5 and R6 are provided.

Also in this embodiment, when the vertical deflection current I flows from the terminal T1, it is divided into two divided currents I1 and I2 by the variable resistor VR1 via the diode D1.
One shunt current I1 flows to the terminal T2 via the fixed resistor R3 and the convergence correction coil L1, and the other shunt current I2 is fixed resistor R4 and the convergence correction coil L.
2 to the terminal T2.

Here, by appropriately setting the resistance values of the fixed resistors R3 and R4, a vertical line converter is obtained from the resistance ratio of the variable resistor VR1 and the resistance ratio of these fixed resistors R3 and R4.
A bias can be added to the presence correction, and the design center value of the vertical line convergence amount can be changed. As a result, the center value of the resistance value variable range of the variable resistors VR1 and VR2 can be matched with the value corresponding to the center of the range of change in the convergence amount of the vertical line, and the adjustment range can be maximized. Further, as in the embodiment shown in FIG. 1, the vertical line convergence correction under the constant VCR condition is performed by adjusting the variable resistor VR1.
This is done by optimizing the ratio of

When the vertical deflection current I flows from the terminal T2, this vertical deflection current I is shunted to the convergence correction coils L1 and L2 and flows, and the fixed resistances R5 and R6.
Via the variable resistor VR2. These converters
The ratio of the currents flowing through the presence correction coils L1 and L2 is optimized by adjusting the variable resistor VR2. The vertical deflection current I synthesized by the variable resistor VR2 returns to the vertical deflection circuit through the diode D2 and the vertical deflection coils VL1 and VL2 which are in the forward direction at this time.

The vertical line convergence correction under the constant VCR condition is performed by adjusting the variable resistor VR2 to optimize the ratio of the divided currents I1 and I2.

In this way, the variable resistors VR1 and VR2 are
Is adjusted, the ratio of the amount of current flowing through the convergence correction coils L1 and L2 can be independently optimized when vertically deflecting the upper half of the CRT screen and when deflecting the lower half. .

Next, a concrete example of the convergence yoke and its operation will be described with reference to FIG. However, 2 is a convergence yoke, and M1 and M2 are magnetic materials.

FIG. 3 (a) shows a first specific example of the convergence yoke 2. In the figure, a pair of magnetic bodies M1 and M2 are attached so as to face each other vertically on the electron gun side of a CRT (not shown), and a convergence correction coil L1 is provided on the magnetic body M1 and a convergence correction is provided on the magnetic body M2. Convergence yoke 2 is configured by providing each coil L2. As described with reference to FIGS. 1 and 2, currents I1 and I2 are applied to the convergence correction coils L1 and L2, respectively, and the convergence correction magnetic field B1 is generated by the convergence correction coil L1. A convergence correction magnetic field B2 is generated by the convergence correction coil L2.

The G (green) beam is made to pass through the portion where the convergence correction magnetic fields B1 and B2 are horizontal, and the R (red) beam.
The beam and the B (blue) beam pass through the portions on both sides of the G beam in the horizontal direction. Therefore, due to the convergence correction magnetic fields B1 and B2, only the electromagnetic force in the vertical direction acts on the G beam, but in the R beam and the B beam, the direction and the convergence of the electromagnetic force by the convergence correction magnetic field B1.
The direction of the electromagnetic force due to the presence correction magnetic field B2 is different. Moreover, as shown in the figure, the electromagnetic force F1R, F due to the convergence correction magnetic field B1 acting on the R beam and the B beam is generated.
The direction of 1B is the assumed vertical axis (hereinafter referred to as the vertical axis)
The opposite direction with respect to the electromagnetic force F2R by the convergence correction magnetic field B2 acting on the R beam and the B beam,
The orientation of F2B is also opposite with respect to the vertical axis.

Here, the magnetic field distributions of the convergence correction magnetic field B1 and the convergence correction magnetic field B2 are as follows:
When the current values of I2 are different, they are not the same, and due to the asymmetry of the convergence correction magnetic fields B1 and B2, the electromagnetic force F1R and the convergence correction magnetic field B2 due to the convergence correction magnetic field B1 that the R beam receives. Electromagnetic force F2 by
A difference occurs in the horizontal (X) component and the vertical (Y) component from R. The same applies to the electromagnetic force F1B due to the convergence correction magnetic field B1 received by the B beam and the electromagnetic force F2B due to the convergence correction magnetic field B2. Thus, the electromagnetic forces F1R, F2R and the electromagnetic forces F1B, F2
Due to the difference between the horizontal (X) component and the vertical (Y) component of B, vertical line misconvergence can be corrected as will be described later with reference to FIG.

FIG. 3B shows a second specific example of the convergence yoke 2. In the figure, in this specific example, two convergence correction coils are provided for each of the magnetic bodies M1 and M2. That is, one magnetic body M
1 includes the convergence correction coils L11 and L12,
The other magnetic member M2 has a convergence correction coil L2.
1 and L22 are provided respectively. Convergence correction coils L11, L provided on one magnetic body M1.
Reference numeral 12 is connected in series to form the convergence correction coil L1 shown in FIGS. 1 and 2, and the convergence correction coils L21 and L2 provided on the other magnetic body M2.
2 are connected in series to form the convergence correction coil L2 shown in FIGS.

As described with reference to FIGS. 1 and 2, the split current I1 is applied to the convergence correction coils L11 and L12, and the convergence correction coils L21 and L2 are also supplied.
The split current I2 is applied to the second coil 2. As a result, FIG.
Similar to the specific example of (a), the convergence correction coils L11 and L12 generate the convergence correction magnetic field B1, and the convergence correction coils L21 and L21.
A convergence correction magnetic field B2 is generated by L22. Also here, when the current values of the divided currents I1 and I2 are different, the magnetic field distributions of the convergence correction magnetic fields B1 and B2 are not the same, and the convergence correction magnetic fields B1 and B2 are not the same.
Due to the asymmetry of 2, the electromagnetic force F1R, which the R beam receives,
A difference occurs in the horizontal (X) component and the vertical (Y) component of F2R. This means that the electromagnetic force F1 against the B beam is
The same applies to B and F2B. Then, due to the difference between the electromagnetic forces F1R and F2R and the difference between the electromagnetic forces F1B and F2B, the vertical line convergence correction can be performed, as described later with reference to FIG.

In this embodiment, there are manufacturing advantages such as the fact that the convergence correction coils L11, L12, L21 and L22 can be wound on bobbins and then attached to the respective magnetic bodies M1 and M2.

FIG. 3C shows a third specific example of the convergence yoke 2. In the figure, two magnetic bodies M1 and M2 are attached so as to face each other in the horizontal direction of the neck portion of the CRT, and the convergence correction coils L11 and L21 are provided on the magnetic body M1 and the convergence correction is performed on the magnetic body M2. Coils for use L12 and L22 are provided respectively.
The convergence correction coils L11 and L12 provided on the different magnetic bodies M1 and M2 are arranged to face each other,
Further, they are connected in series to form the convergence correction coil L1 shown in FIGS. 1 and 2, and the divided current I1 flows. Further, the convergence correction coils L21 and L22 provided on the different magnetic bodies M1 and M2 are also arranged to face each other and connected in series to form the convergence correction coil L2 shown in FIGS. None, the divided current I2 flows.

Therefore, as in the previous embodiment, the convergence correction magnetic fields B1 are generated by the convergence correction coils L11 and L12, and the convergence correction magnetic field B2 is generated by the convergence correction coils L21 and L22. Is generated. When the current values of the divided currents I1 and I2 are different, the magnetic field distributions of the convergence correction magnetic fields B1 and B2 are not the same, and the convergence correction magnetic field B is not the same.
The electromagnetic force F received by the R beam due to the asymmetry of 1 and B2
A difference occurs in the horizontal (X) component and the vertical (Y) component of 1R and F2R. This also applies to the electromagnetic forces F1B and F2B on the B beam. Then, due to the difference between the electromagnetic forces F1R and F2R and the difference between the electromagnetic forces F1B and F2B, the vertical line convergence correction can be performed, as described later with reference to FIG.

Next, in the specific example shown in FIGS. 3A to 3C, the R beam will be taken as an example to explain the correcting action of the vertical line misconvergence due to the electromagnetic force with reference to FIG. However, FT is the electromagnetic force FB received by the R beam by the convergence correction magnetic field B1 in FIGS. 3 (a) to 3 (c).
Is the convergence correction magnetic field B2 in FIGS. 3 (a) to 3 (c).
The electromagnetic force received by the R beam by F beam, FTX, FBX is the horizontal (X) component of electromagnetic force FT, FB, FTY, FBY, respectively.
Is the vertical (Y) component of the electromagnetic forces FT and FB, FX is the combined force of the horizontal (X) components FTX and FBX of the electromagnetic forces FT and FB, and FY is the vertical (Y) component FTY of the electromagnetic forces FT and FB,
It is the synthetic power of FBY.

In FIG. 4, when there is a difference in the partial currents I1 and I2 as described with reference to FIGS. 1 and 2, the electromagnetic forces FT and FB generated in the R beam are opposite to each other with respect to the vertical axis Y passing through the R beam. The orientation, and therefore the horizontal (X) components FTX, FBX of these electromagnetic forces FT, FB, are opposite to each other with respect to the R beam. Assuming that the screen is viewed from the side opposite to the electron gun in FIG. 4, the horizontal (X) component F of the electromagnetic force FT is
TX points to the left and the horizontal (X) component FB of the electromagnetic force FB
Assuming that X is pointing to the right, the horizontal (X) component FT
Assuming that X is larger than the horizontal (X) component FBX, the resultant force FX of the horizontal (X) components FTX and FBX is directed to the left as shown in the figure, and thus the R beam is caused by this resultant force FX. It is deflected to the left.

On the other hand, for the B-beam, the electromagnetic forces FT and FB acting on the B-beam have a relation inverted with respect to the vertical axis Y in FIG. 4, so that the B-beam is deflected to the right.

Therefore, in FIG. 5 showing the case where the CRT screen is viewed from the front side of the panel, the R vertical line passes through the center of the screen as shown by the solid line and shifts to the right above and below the screen, and the B vertical line as shown by the broken line. When a misconvergence occurs in which the line passes through the center of the screen and shifts to the left and right at the top and bottom of the screen, the R beam is deflected to the left as it goes up and down due to the action shown in FIG. 4, and the B beam also appears on the screen. It is deflected to the right as you go up and down,
As these beams are deflected above and below the screen by the vertical deflection coil, the current flowing through the convergence correction coil increases, and the horizontal (X) component of the electromagnetic forces FT and FB increases. Misconvergence can be corrected.

Here, as shown in FIG. 5, even if the misconvergence amount of the vertical line is different between the upper part and the lower part of the screen, the divided currents I1 and I2 in FIGS. By adjusting the variable resistors VR1 and VR2, the divided currents I1 and I2 when vertically deflecting the upper portion of the screen are adjusted.
And the partial current I1, when vertically deflecting the lower part of the screen.
Since the ratio of I2 can be adjusted independently, the misconvergence between the upper part and the lower part of the screen can be independently corrected.

When the direction of misconvergence of the vertical line is opposite to that in FIG. 5 (that is, the R beam is in the left direction of the screen,
In the case where the beams are shifted to the right of the screen respectively), as shown in FIGS. 1 and 2, the direction of the flow of the partial currents I1 and I2 in the convergence correction coils L1 and L2 is reversed so that the convergence is reversed. The winding directions or connection directions of the presence correction coils L1 and L2 may be reversed.

[0043]

As described above, according to the present invention,
Misconversion of vertical lines occurring at the top and bottom of the CRT screen
The presence can be corrected independently, and even if the amount of misconvergence is different between the upper portion and the lower portion of the CRT screen, it is possible to sufficiently correct each.

Since a constant bias can be applied to the vertical line convergence correction, the design center value of the vertical line misconvergence amount can be changed.
More accurate vertical line convergence correction becomes possible.

Further, according to the present invention, the convergence correction coil is divided into two and provided on the magnetic body, so that the convergence correction coil can be wound and then attached to the magnetic body. Manufacturing is simple.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a convergence correction device according to the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the convergence correction device according to the present invention.

FIG. 3 is a diagram showing a specific example of the convergence yoke in the embodiment shown in FIGS. 1 and 2 and a magnetic field generated thereby.

FIG. 4 is a diagram for explaining correction of vertical line misconvergence due to the action of the magnetic field shown in FIG. 3;

FIG. 5 is a diagram showing an example of vertical line misconvergence.

[Explanation of symbols]

1 Convergence Yoke Drive Circuit 2 Convergence Yoke VL1, VL2 Vertical Deflection Coil D1, D2 Diode R1-R6 Fixed Resistor VR1, VR2 Variable Resistor L1, L2, L11, L12, L21, L22 Convergence Correction coil T1, T2 terminal P1 contact I Vertical deflection current I1, I2 Current distribution M1, M2 Magnetic material B1, B2 Convergence correction magnetic field F1R, F2R R Electromagnetic force F1B, F2B B beam received by beam Electromagnetic force received FT Electromagnetic force received by R beam due to convergence correction magnetic field B1 FB Electromagnetic force received by R beam due to convergence correction magnetic field B2 FTX Horizontal (X) component of electromagnetic force FT FBX Electromagnetic force FB Horizontal (X) component FTY Electromagnetic force FT vertical (Y) component FBY Electromagnetic force FB vertical (Y) component FX Electromagnetic force FT , FB horizontal (X) component FTX, FB
Combined force of X FY Electromagnetic force FT, FB vertical (Y) component FTY, FB
Synthetic power of Y

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Soichi Sakurai 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Ltd. Inside the Visual Media Research Laboratory, Hitachi, Ltd. (72) Inventor ▲ Yoshi ▼ Hiroshi Oka 3300 Hayano, Mobara-shi, Chiba Address Hitachi Electronics Co., Ltd. Electronic Device Division (72) Inventor Yoshihiro Ohara No. 1 Kitano, Masaki, Mizusawa-shi, Iwate Prefecture Hitachi Mizusawa Electronics Co., Ltd. (72) Nobutaka Okuyama 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Ceremony Company Hitachi Media Media Research Laboratories

Claims (5)

[Claims] 1. A convergence correction device mounted on a color cathode ray tube using a multi-electron beam of an in-line arrangement, comprising a convergence yoke drive circuit and a plurality of magnetic bodies provided for each magnetic body. A convergence correction coil, wherein the convergence yoke drive circuit is connected to each of the diodes and at least one pair of diodes connected to the vertical deflection coil in opposite directions and connected in parallel. And a variable resistor that divides a vertical deflection current flowing through the vertical deflection coil into each of the convergence correction coils, and the vertical deflection current flows through different diodes and variable resistors according to the flowing direction thereof. By adjusting the variable resistance, vertical line misconvergence that occurs at the top and bottom of the screen can be independently corrected. Convergence correction device. 2. The vertical line converter according to claim 1, wherein a fixed resistor having a predetermined resistance value is connected in series for each variable resistor, and a bias is added by the fixed resistor.
A convergence correction device characterized in that the design center value of the amount of presence can be changed. 3. The convergence according to claim 1, wherein one set of the magnetic bodies is arranged in the vertical direction, and one convergence correction coil is provided for each magnetic body. Correction device. 4. The convergence correction coil according to claim 1, wherein one set of the magnetic bodies is arranged in a vertical direction, and the convergence correction coil including two coils connected in series is provided for each magnetic body. Convergence correction device. 5. The magnetic sensor according to claim 1 or 2, wherein one set of the magnetic bodies is arranged in the horizontal direction, and the convergence correction coil is composed of a set of two coils connected in series. A convergence correction device, wherein the two coils forming the correction coil are provided on different magnetic bodies.