JP2001128188A - Convergence correcting circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a convergence correcting circuit which can suppress the occurrence of miss-convergence by a fish tail which occurs at the scanning end section of an electron beam in a deflection yoke device. SOLUTION: The convergence correcting circuit which is connected in series with the vertical deflection coil of a deflection yoke and provided with a coil for correcting convergence contains an Yh correcting section which corrects miss-convergence in the same direction with respect to the vertical direction of a screen. The Yh correcting section is provided with at least one diode and all diodes of the correcting section are connected in such a way that an electric current flows only when vertical deflection is made in the same direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a convergence correction circuit for a deflection yoke used in a cathode ray tube such as a television receiver and a color monitor display.

[0002]

2. Description of the Related Art In cathode ray tubes used for television receivers, color monitor displays, etc., red
(R), blue (B), and green (G) The three electron beams that excite and emit phosphors of the three primary colors are the same position on the screen of the cathode ray tube when displaying a white line or point. Is ideal, but due to design limitations of the deflection yoke and the cathode ray tube and manufacturing variations, the three electron beams do not reach the same point and a certain degree of misconvergence occurs.

Therefore, in order to minimize such misconvergence, the deflection current is controlled by a circuit attached to the deflection yoke to change the balance of the current flowing into the main deflection coil or to correct the current applied to the deflection yoke. At the design stage, countermeasures such as using a convergence correction circuit for correcting the convergence by supplying the convergence to the supply coil are taken.

[0004] Regarding manufacturing variations, a sheet-like magnetic piece made of ferrite or the like is inserted between the inner surface of the deflection yoke and the outer surface of the cathode ray tube, or a magnetic material is attached to the end of the deflection yoke on the electron gun side. Measures have been taken to correct the magnetic field, such as by attaching pieces or by eccentrically attaching the deflection yoke and the electron gun to each other.

FIG. 4 shows a conventional correction circuit for misconvergence in the Y-axis (vertical) direction.

In FIG. 4, (1) is a Yh skew correction unit which corrects the misconvergence Yh Skew in the direction opposite to the vertical direction of the screen shown by the broken line in FIG. 5 by adjusting the variable resistor VR2. (2) is a Yh correction unit which adjusts the variable resistor VR1 to
Misconvergence Yh in the same direction with respect to the vertical direction of the screen shown by the broken line in FIG. 6 is corrected. Note that FIG.
In FIG. 6, the misconvergence of blue (B) with red (R) as a reference is shown by a broken line.

[0007]

However, in the conventional convergence correction circuit as shown in FIG. 4, a so-called fish in which misconvergence suddenly increases at the scanning end of the electron beam as shown by the broken line in FIG. Misconvergence called the tail was occurring.

[0008] Such fish tails are especially Yh S
The convergence correction coil of the keW correction unit and the convergence correction coil of the Yh correction unit appear remarkably in the case of being wound around the same magnetic core in order to save installation space. Also, it is possible to reduce the overscan amount, which makes the electron beam scan width larger than the screen size,
A large fish tail also appears when the vertical deflection frequency is increased.

Misconvergence that appears at the scanning end of the electron beam, such as the fishtail, cannot be corrected by the conventional convergence correction circuit as shown in FIG.

As a measure for improving such a fish tail,
A method of increasing the resistance value of the closed circuit portion including each convergence correction coil is considered, but such a convergence correction circuit is connected in series with the vertical deflection coil, and limits the vertical output voltage and the like of the deflection yoke. However, there was no sufficient improvement.

Accordingly, the present invention provides a convergence correction circuit capable of suppressing misconvergence at the scanning end of the electron beam.

[0012]

In order to solve the above problems, a convergence correction circuit according to the present invention has a convergence correction circuit connected in series with a vertical deflection coil of a deflection yoke and provided with a coil for correcting convergence. , The convergence correction circuit includes a Yh correction unit that corrects misconvergence in the same direction with respect to the vertical direction of the screen, the Yh correction unit includes at least one diode, and all the diodes are in the same direction. The connection is such that current flows only during vertical deflection.

The convergence correction circuit according to the present invention further includes a Yh Skew correction unit for correcting misconvergence in a direction opposite to the vertical direction of the screen,
Further, a coil for correcting misconvergence of the Yh correction unit and a coil for correcting misconvergence of the Yh Skew correction unit may be wound around the same magnetic core.

[0014]

FIG. 1 shows an embodiment of a convergence correction circuit according to the present invention.

In FIG. 1, (1) is a Yh skew correction section, (2) is a Yh skew correction section, and the Yh skew correction section (1) is the same as the Yh skew correction section of the conventional circuit shown in FIG.

The feature of this embodiment is that the Yh correction unit (2)
That is, the diode D1 in the conventional circuit of FIG. 4 is not provided. That is, in the conventional circuit, when a current flows from the top to the bottom of the paper (when the electron beam scans in the upward direction of the screen), a current flows through the diode D2,
When current flows from the bottom to the top of the page (when the electron beam scans down the screen), current flows through the diode D1, so current flows through one of the diodes in both directions during vertical deflection However, in this embodiment, the current flows through the diode D2 only when the current flows from the top to the bottom of the paper (when the electron beam scans in the upward direction of the screen), and when the current flows from the bottom to the top of the paper ( No current flows through the diode when the electron beam scans down the screen).

In such an embodiment, the misconvergence Yh Skew in the direction opposite to the vertical direction of the screen is defined as:
FIG. 2 (a) shows the result of measuring the fishtail when the correction is made by adjusting the central axes of the cathode ray tube and the deflection yoke and the value of the variable resistor VR2 of the Yh Skew correction unit (1) is taken as the center. Misconvergence Yh Skew in the reverse direction to the vertical direction of
After adjusting by adjusting the variable resistor VR2 of
FIG. 2B shows the results of measuring the fishtail of the conventional circuit and the present example. FIG. 2 shows the misconvergence amount on the horizontal axis with the vertical axis being the vertical direction of the screen (the center of the screen is assumed to be 0). The red (R) misconvergence is based on the green (G) of the electron beam. With a solid line, blue (B)
Are indicated by broken lines.

Next, the same measurement was performed on the conventional circuit shown in FIG. The results are shown in FIGS. In this embodiment and the conventional circuit, the coil for correcting the misconvergence of the Yh skew correction unit (1) and the coil for correcting the misconvergence of the Yh correction unit (2) are wound around the same magnetic core.

2 and 3, it can be seen that in this embodiment, the amount of misconvergence in the fish tail is suppressed as compared with the conventional circuit.

From the comparison between FIG. 2B and FIG. 3B,
In the present embodiment, the coil of the Yh correction unit and the Yh Sk
The coil of the ew correction unit is wound around the same magnetic core, and Yh
It can be seen that the phenomenon that the fish tail becomes remarkable when the adjustment is performed by the skew correction unit can be suppressed.

In this embodiment, only one diode D2 is used, but a plurality of diodes may be used to adjust misconvergence. However, in this case, the conduction directions of all the diodes must be aligned in one direction.

In the Yh correction unit (2) of this embodiment, there is no diode that conducts when a current flows from the bottom to the top of the page (when the electron beam scans in the downward direction of the screen). In the correction of misconvergence in the same direction as the vertical direction, the correction amount for the lower deflection is larger than the correction amount for the upper deflection. However, when the state shown in FIG. 6 is corrected, since the amount of correction at the time of downward deflection is large, the variable resistor VR1 is adjusted to adjust the state shown in FIG.
Then, misconvergence can be corrected using the variable resistor VR2, and the convergence correction circuit can be used without any practical problem.

[0023]

As described above, in the convergence correction circuit according to the present invention, the fish tail appearing at the scanning end of the electron beam can be suppressed. Therefore,
A high-definition convergence characteristic can be obtained even in a progressive double-speed television having a vertical deflection frequency twice as high as the conventional one and a small overscan amount.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing misconvergence due to fish tails in the embodiment.

FIG. 3 is a diagram showing misconvergence due to fishtail in a conventional example.

FIG. 4 is a circuit diagram showing a conventional example of a convergence correction circuit.

FIG. 5 is a diagram showing misconvergence occurring in a direction opposite to a vertical direction of a screen.

FIG. 6 is a view showing misconvergence that occurs in the same direction as the vertical direction of the screen.

FIG. 7 is a diagram showing misconvergence caused by fish tails.

[Explanation of symbols]

 (1) Yh skew correction unit (2) Yh correction unit D1, D2 Diode VR1, VR2 Variable resistor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsumi Sakamoto 1-1, Sanyocho, Daito-shi, Osaka Sanyo Electronics Components Co., Ltd. F-term (reference) 5C060 BE07 CE01 CF01 HA03 HA14 JA01

Claims (3)

[Claims] 1. A convergence correction circuit connected in series with a vertical deflection coil of a deflection yoke and provided with a coil for correcting convergence, wherein the convergence correction circuit reduces misconvergence in the same direction with respect to the vertical direction of the screen. A convergence correction unit comprising: a Yh correction unit for correcting, wherein the Yh correction unit includes at least one diode, and all of the diodes are connected so that current flows only during vertical deflection in the same direction. circuit. 2. The convergence correction circuit according to claim 1, further comprising a Yh Skew correction unit for correcting misconvergence in a direction opposite to a vertical direction of the screen. 3. The convergence according to claim 2, wherein the coil for correcting misconvergence of the Yh correction unit and the coil for correcting misconvergence of the Yh Skew correction unit are wound around the same magnetic core. Correction circuit.