JPH1066002A - Dynamic focus circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve precision in the voltage of a finally required parabolic waveform and to standardize a transformer for waveform amplification by suppressing the influence upon horizontal linearity to a negligible degree concerning a dynamic focus circuit (DAF circuit). SOLUTION: Parallelly with a capacitor 1 for S curve correction, an instrument serially connecting capacitors more than two having capacitances sufficiently less than that of the capacitor 1 for S curve correction is attached and from both terminals of one of these capacitors, a voltage is supplied to the primary winding wire of the transformer for waveform amplification. The voltage of the parabolic waveform having an optimum amplitude can be provided and the influence upon horizontal linearity can be suppressed to a negligible degree. Besides, the transformer for amplification corresponding to small-lot large-kind production can be standardized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DAF circuit (dynamic focus circuit) used for a cathode ray tube (CRT) display device.

[0002]

2. Description of the Related Art In a DAF circuit for obtaining a voltage of a parabola waveform having a horizontal cycle, a DAF circuit in which a primary winding of a transformer for waveform amplification and a capacitor are connected in series is attached in parallel with a capacitor for S-shaped correction. A method of obtaining a parabolic waveform voltage from both ends of a secondary winding of a transformer has been used.

FIG. 2 shows an example of a circuit diagram of a conventional DAF circuit for obtaining a voltage of a parabolic waveform having a horizontal cycle. A parabolic waveform voltage generated at both ends of the S-shaped correction capacitor 1 causes a primary winding of the waveform amplifying transformer 4 and a secondary winding of the waveform amplifying transformer 4 by passing current through the capacitors 3 and 5. The voltage of the horizontal period parabolic waveform was obtained at both ends. (JP-A-54-155721)

[0004]

The amplitude of the parabolic waveform obtained in this way is adjusted by setting the turns ratio of the waveform amplifying transformer. For this reason, accuracy is poor, and it is necessary to change the winding specification of the transformer for each model in small lot multi-model production, and it has not been possible to standardize the transformer. Further, when a capacitor in which a capacitor is connected in series is attached in parallel with the S-shaped capacitor, there is a problem that the horizontal linearity is greatly affected.

[0005]

In order to solve the above-mentioned problems, a DAF circuit according to the present invention comprises two or more capacitors having a capacity sufficiently smaller than the capacity of the S-shaped correction capacitor in parallel with the S-shaped correction capacitor. Are connected in series, and a voltage is supplied from both ends of one of the capacitors to the primary winding of the transformer for amplifying the waveform.

According to the present invention, the influence on the horizontal linearity is suppressed to a negligible level, the voltage accuracy of the finally required parabolic waveform is improved, and a transformer for waveform amplification is used in order to cope with the production of small lots and many models. DA that can be standardized
An F circuit is provided.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention described in claim 2 of the present invention is directed to a dynamic focus circuit (hereinafter abbreviated as DAF circuit) which requires a voltage of a parabolic waveform having a horizontal period, and is provided in parallel with an S-shaped correction capacitor. Attach two or more capacitors of a capacity sufficiently smaller than the capacity of the S-shaped capacitor in series, and connect the capacitor in series with the primary winding of the transformer for waveform amplification in parallel with one of these capacitors. A DAF circuit that obtains a parabolic waveform voltage with high accuracy from both ends of the secondary winding of the transformer by attaching a transformer that has two or more capacitors in parallel with the S-shaped correction capacitor. By attaching the connected one and changing the capacitance ratio of this capacitor, the amplitude of the parabolic waveform voltage applied to the primary winding of the transformer can be adjusted, It has an effect of following the winding ends in can be obtained parabolic waveform with high precision horizontal period of.
Further, since the amplitude of the parabolic waveform voltage can be adjusted by changing the capacitance ratio of the capacitor, it is not necessary to adjust the amplitude by changing the winding specification of the transformer.

Further, by selecting the capacity of the capacitor connected in parallel with the S-shaped capacitor to be sufficiently smaller than that of the S-shaped capacitor, the total capacitance change of the S-shaped capacitor can be suppressed to a very small extent. The effect on the horizontal linearity can be reduced to a negligible level.

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment) FIG. 1 shows a DAF for generating a voltage having a horizontal period of a parabolic waveform according to an embodiment of the present invention.
It is a circuit diagram of a circuit. This DAF circuit is composed of capacitors 2 and 3 for amplitude adjustment, a transformer 4 for waveform amplification, and a capacitor 5 with respect to the S-shaped correction capacitor 1 which is a part of the horizontal deflection circuit.

In the DAF circuit configured as described above, the voltage of the parabolic waveform generated at both ends of the S-shaped correction capacitor 1 is divided by the capacitance ratio of the capacitors 2 and 3 for amplitude adjustment. The amplitude of the voltage of the parabolic waveform applied to both ends of is adjusted. The parabolic waveform voltage having the adjusted amplitude is applied to the primary winding of the waveform amplifying transformer 4 and both ends of the capacitor 5 so that the transformer 4
A voltage having a parabolic waveform corresponding to the ratio between the primary winding and the secondary winding is generated at both ends of the secondary winding of the transformer 4. Here, the capacitors 2 and 3 are adjusted so that the amplitude of the parabolic waveform generated at both ends of the secondary winding of the transformer 4 becomes optimal.
By adjusting the ratio, a parabolic waveform with high voltage amplitude accuracy can be obtained. Also, since the amplitude of the parabolic waveform can be adjusted by changing only the capacitors 2 and 3, the components of the waveform amplifying transformer 4 can be standardized. Further, by setting the capacitances of the capacitors 2 and 3 sufficiently smaller than the capacitance of the capacitor 1 for S-character correction, the total S-characteristic correction capacitance C0 becomes C0 = C1 + (C2 + C3) / (C2 × C3) ≒ C1 Thus, the influence on the horizontal linearity can be suppressed to a negligible level. (However, C1 is the capacity of the S-shaped correction capacitor 1, C2 is the capacity of the capacitor 2, C3
Is the capacity of the capacitor 3, C1≫C2, C3)

[0012]

As described above, by connecting two or more capacitors having a sufficiently smaller capacity than the S-shaped capacitor in parallel with the S-shaped capacitor and adjusting the amplitude of the parabolic waveform, the voltage of the parabolic waveform having the optimum amplitude is adjusted. And the influence on the horizontal linearity can be suppressed to a negligible level. In addition, since the amplitude of the parabolic waveform can be adjusted by changing the capacitance ratio of the capacitor, the standardization of the amplifying transformer for small lot multi-model production can be realized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a DAF circuit according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a conventional DAF circuit.

[Explanation of symbols]

 1 S-shaped correction capacitor 2 Amplitude adjustment capacitor 3 Amplitude adjustment capacitor 4 Waveform amplification transformer 5 Capacitor

Claims (2)

[Claims] 1. A dynamic focus circuit characterized in that the amplitude of a horizontal period parabola voltage waveform generated at both ends of an S-shaped capacitor is adjusted to obtain an accurate parabola voltage waveform. 2. A capacitor in which two or more capacitors having a capacity smaller than the capacity of the S-shaped capacitor are connected in series with the S-shaped correction capacitor, and a capacitor for waveform amplification is further provided in parallel with one of the capacitors. The primary winding of the transformer and the capacitor connected in series are attached.
A dynamic focus circuit characterized by obtaining a parabolic waveform voltage from both ends of the next winding.