JPH02130091A - Convergence correcting circuit - Google Patents

Abstract

PURPOSE:To facilitate the convergence adjustment and to curtail the adjusting manday by detecting the current to flow at a convergence yoke coil corresponding to the center of the picture by a clamping circuit, and controlling the discharging current of a capacitor so that the valve of the current attain a prescribed value. CONSTITUTION:The current to flow at a convergence yoke coil 3 corresponding to the center of a picture is detected by a clamping circuit 5. The discharging current of the convergence yoke coil 3 and a capacitor 4 of the serial connection is controlled so that the valve of the detected current attain a prescribed value, for example, DC=OA. The correcting current to flow at the convergence yoke coil 3 is clamped, for example, to DC=OA. Thus, even when the convergence adjustment is executed by the 5-point adjustment, the convergence is fixed at the picture center as it is, not moved, the adjustment is made very easy and the adjusting manday can be curtailed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a convergence correction circuit suitable for use in CRT display devices such as television receivers and monitors.

[Summary of the invention]

This invention provides a convergence correction circuit in which a convergence yoke coil is connected to a convergence yoke coil +1llJ driven by a convergence correction current, and a clamp circuit is provided in series with the convergence yoke coil. By detecting the current flowing through the coil and controlling the discharge current of the capacitor so that the current value becomes a predetermined value, convergence adjustment is made easier and the number of adjustment steps is reduced. .

[Conventional technology]

Conventionally, when convergence adjustment is performed in a convergence correction circuit, adjustment is performed over a plurality of points, and so-called 5-point adjustment is one such adjustment. For this 5 point adjustment, 11・AMP adjustment, )! -TIL
T adjustment, Y-8 open adjustment, C-BOW adjustment and Y-CR
There is O3S adjustment. 11. AMP adjustment changes the level of the horizontal parabolic wave by varying the voltage source in the circuit. 1
1.TILT adjustment is performed by moving the phase of the horizontal parabolic wave. In the Y-BO-adjustment, a vertical parabolic wave is added to the horizontal component of the current flowing through the convergence yoke coil by adding a vertical parabolic wave current source. c.
-Bow1 round adjustment modulates the amplitude of the horizontal component of the correction current flowing through the convergence yoke coil in a vertical parabolic manner by modulating the current flowing through the convergence circuit that generates the horizontal component in a vertical parabolic manner. Y-CROS
The S adjustment is performed by superimposing a vertical sawtooth wave on the correction current waveform of the convergence yoke coil.

[Problem to be solved by the invention]

By the way, in the case of the conventional convergence correction circuit that performs convergence adjustment using the 5-point adjustment as described above, 1
Every time you move two adjustment VRs, the convergence at the center of the screen moves, and each time you move, you have to adjust the convergence at the center of the screen using the so-called H-5TATνR, which is related to a CRT.As a result, it is very difficult to make adjustments. There were drawbacks such as increased man-hours.

The present invention has been made in view of this problem, and it is an object of the present invention to provide a convergence correction circuit that fixes the convergence at the center of the screen even when convergence adjustment is performed, making it easy to adjust and reducing the number of adjustment steps.

[Means for Solving the Problems] A convergence correction circuit according to the present invention includes a convergence yoke coil (3) and a capacitor (4) connected in series with a convergence yoke coil (3) driven by a convergence correction current. A clamp circuit (5) is provided in series with 3), and this clamp circuit (5) detects the current flowing through the convergence yoke coil (3) corresponding to the center of the screen, so that the value of this current becomes a predetermined value. It is configured to control the discharge current of the capacitor (4).

[Operation] The clamp circuit (5) detects the current flowing through the convergence yoke coil (3) corresponding to the center of the screen.

Then, the value of this detected current is set to a predetermined value, for example, DC=O
The discharge current of the convergence yoke coil (3) and the capacitor (4) connected in series is controlled so that the current is A. That is, the correction current flowing through the convergence yoke coil (3) is clamped to, for example, DC=OA. As a result, even if the convergence is adjusted by 5-point adjustment, the convergence remains fixed at the center of the screen and does not move, making the adjustment extremely easy and reducing the number of adjustment steps.

(Example) Hereinafter, an example of the present invention will be described in detail based on FIGS. 1 and 2.

Figure 1 shows the circuit configuration of this embodiment, where (1) is the input terminal to which the convergence correction current is supplied, (2) is the amplifier, (3) is the convergence yoke coil, and (4) is the input terminal to which the convergence correction current is supplied.
) is a capacitor. A clamp circuit (5) is placed between this convergence yoke coil (3) and the capacitor (4).
will be provided. This clamp circuit (5) is a diode (
6), (7), a capacitor (8), a transistor (9), a resistor (to), and (II). The anode of the diode (6) is connected to the convergence yoke coil (
3) and its cathode is connected to one end of the capacitor (4
) is connected to one end of the

The cathode of the diode (7) is connected to the connection point between the convergence yoke coil (3) and the diode (6), and its anode is connected to the transistor (9) via a resistor (00).
It is connected to the base of the diode (6) and the capacitor (4) and to the emitter of the transistor (9) via the capacitor (8). The collector of the transistor (9) is connected via a resistor (11) to an input terminal 02 to which a vertical parabolic wave is applied, and is also connected to the base of 20 stages of transistors which also serve as a current source for the vertical parabolic wave. The emitter on the transistor side is resistor 0
grounded through the hair, whose collector is a diode (6)
and the connection point of the capacitor (4).

Further, the clamp circuit (5) has a plurality of current limiting elements such as diodes (15,) to (153) for preventing the capacitor (8) from being excessively charged, and these diodes (151) ~ (153) has its anode side facing the capacitor (4) side, and its cathode side facing the diode (
7) Connected in parallel to the capacitor (8) so as to face the side.

Next, the operation of the circuit shown in FIG. 1 will be explained with reference to FIG. 2. In this embodiment, as shown in FIG. 2, the convergence correction current is applied to
The clamp circuit (5) clamps the voltage to a predetermined value, for example, DC=OA, as shown in FIG. Normally, the convergence correction current flows in the direction shown by the arrow a in Figure 1, but if there is no clamp circuit (5), the waveform of the convergence correction current is shifted by the error amount e and becomes a broken line as shown in Figure 2B. DC=OA will be located at . In other words, when the current becomes negative, it means that the convergence correction current flows in the direction opposite to the arrow a. Therefore, in this embodiment, the negative portion is detected by the clamp circuit (5) and the DC current is shifted in the positive direction by that amount.

To explain this in more detail, as mentioned above, when the convergence correction current becomes negative, it means that the current flows in the opposite direction to arrow a, but here, if the convergence correction current becomes even slightly negative, The capacitor (8) is charged by passing current in the direction indicated by the arrow in FIG. In other words, this capacitor (
8) The amount of current that becomes negative due to charging is detected.

When the capacitor (8) discharges, a current flows in the direction shown by arrow C in Figure 1, and at the same time, the transistor (9) turns on and current flows in the direction shown by arrow d in Figure 1. . As the current flows in the direction shown by arrow d, the DC level on the transistor side changes. At that time, so that the convergence correction current flows in the direction of arrow a, that is, in the direction of shifting to the positive side, the change in the DC level of the current source due to the transistor side and resistor 07I is substantially changed by the capacitor (4) and diode (6). It is fed back to the connection point.

As a result, the convergence correction current is clamped to DC=OA with respect to the point P at the center of the screen as shown in Figure 2.
Even if the convergence is adjusted using the 5-point adjustment, the convergence is fixed at the center of the screen and does not move.

The clamp circuit (5) has a high gain, so that if the convergence correction current becomes negative even by a small amount, the gain is amplified to double the gain. Further, the discharge time constants of the capacitor (8) and resistor 00) are set long enough to sufficiently follow the vertical period. Further, in this circuit, when the power is turned on, a large current momentarily flows in the negative direction and charges the capacitor (8). Then, the capacitor (8) is discharged, but as described above, since the discharge time constant of the capacitor (8) and the resistor 0ω is long, it takes a very long time for the capacitor (8) to discharge. Therefore, in order to limit excessive charging of the capacitor (8), the diodes (15,) to (15z) described above are used.
This means that it is added.

In this way, in this embodiment, in order to clamp the convergence correction current corresponding to the center of the screen at DC=OA, the portion where the convergence correction current becomes negative is detected by charging the capacitor (8), and the distributed type let me,
Since the convergence correction current is shifted in the positive DC direction by this amount of discharge, even if convergence is adjusted using 5-point adjustment, the convergence is fixed at the center of the screen and does not move, making adjustment very easy. , the adjustment man-hours can be reduced.

Note that in the above embodiment, the convergence correction current is DC.
Although the clamping is performed at =OA, the present invention is not limited to this, and the clamping may be performed at any DC current value.

Furthermore, by adding a circuit that can change the clamp point using a DC voltage, static convergence adjustment becomes possible using a pass line.

〔Effect of the invention〕

As described above, according to the present invention, a clamp circuit is provided in series with the convergence yoke coil, and the clamp circuit detects the current flowing through the convergence yoke coil corresponding to the center of the screen, and adjusts the current value to a predetermined value. Since the discharge current of the capacitor in series with the convergence yoke coil is controlled, the convergence can be fixed and not move at the center of the screen even if the convergence is adjusted by 5-point adjustment etc.
This makes adjustment easier and reduces adjustment man-hours.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a diagram for explaining the operation of FIG. (3) is a convergence yoke coil, (4) is a capacitor, and (5) is a clamp circuit.

Claims (1)

[Claims] In a convergence correction circuit in which a capacitor is connected in series with a convergence yoke coil driven by a convergence correction current, a clamp circuit is provided in series with the convergence yoke coil, and the clamp circuit corresponds to the center of the screen. A convergence correction circuit comprising: detecting a current flowing through the convergence yoke coil; and controlling a discharge current of the capacitor so that the value of the current becomes a predetermined value.