JPH06164957A - Vertical output circuit for multiscan monitor - Google Patents

Abstract

PURPOSE:To obtain a vertical output circuit for a multiscan monitor capable of supplying deflection currents whose linearity is satisfactory regardless of a using frequency only by supplying a constant voltage to one edge of a vertical deflection coil, thereby setting the constant of a DC negative feedback circuit. CONSTITUTION:The vertical output circuit is constituted of a vertical driving circuit 1 which supplies tooth-shaped currents to a vertical deflection coil 2, DC negative feedback circuit 3 which corrects the linearity of the output signal of the circuit 1, and AC negative feedback circuit 4 with which a capacitor 5 for DC cut is connected, which improves the stability of the circuit 1. Then, a circuit 7 for supplying the constant voltage is connected with the vertical output circuit. The circuit 7 is equipped with complement-connected NPN type and PNP type transistors, and an output from a connecting point 8 is outputted to the deflection coil 2. Also, the complement-connected transistors are equipped with a parallel circuit in which two diodes are serially connected, and the constant voltage from a middle point 9 is applied to the bases of the transistors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical output circuit of a multi-scan monitor which supplies a deflection current having good linearity at different vertical scanning frequencies.

[0002]

2. Description of the Related Art Conventionally, in order to remove the distortion of the sawtooth wave current (deflection current) flowing in the deflection coil which causes the top or bottom of the screen to expand or contract, linearity is obtained by applying negative feedback to the vertical drive circuit. Was corrected. In the multi-scan monitor, for example, since the range of the corresponding vertical scanning frequency extends from 50 to 120 Hz, the linearity is corrected by changing the characteristic of the negative feedback circuit according to the frequency used. FIG. 3 shows a conventional vertical output circuit. A vertical drive circuit 20 supplies a sawtooth current (iL) to the vertical deflection coil 21. Reference numeral 22 is a DC (direct current) negative feedback circuit that corrects the linearity, and 23 is an AC for improving the stability of the circuit.
(AC) Negative feedback circuit. FIG. 4 is an equivalent circuit of the conventional vertical output circuit (FIG. 3). Reference numeral 25 represents a variable voltage source equivalent to the capacitor C1. FIG. 5 shows the waveform of each part of the conventional vertical output circuit. Reference numeral 30 denotes a voltage waveform output from the vertical drive circuit 20, and a sawtooth wave current iL (31) flows as a charging / discharging current of the capacitor C1 via the vertical deflection coil 21 by this voltage waveform. The voltage EC (32) across the capacitor C1 or the parabolic waveform becomes gentle. By appropriately selecting the constant of the DC negative feedback circuit, the sawtooth wave current iL (31) is corrected, and the sawtooth wave current (33) having good linearity can be obtained. But on a multi-scan monitor,
Since the vertical frequency used is often changed, the impedance of the capacitor C1 changes accordingly, and the parabolic waveform of the voltage EC (32) across the capacitor C1 changes. Therefore,
Since the sawtooth current that causes the top or bottom of the screen to expand or contract is also distorted, the linearity had to be corrected each time by changing the constant of the DC negative feedback circuit. Another conventional method is to change the impedance according to the vertical frequency to be used, remove the capacitor that causes the distortion of the sawtooth current, and use a vertical drive circuit that requires two positive and negative power supplies.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and by supplying a constant voltage to one end of a vertical deflection coil, the constants of the DC negative feedback circuit are set to one set. In other words, it is an object of the present invention to provide a vertical output circuit of a multi-scan monitor that supplies a deflection current with good linearity regardless of the frequency used.

[0004]

To achieve the above object, a vertical drive circuit for amplifying an input signal, a deflection coil connected in series with an output of the vertical drive circuit, and an output of the vertical drive circuit are connected to a direct current. It comprises a circuit for negative feedback, a circuit for AC negative feedback of the output of the vertical drive circuit via the deflection coil and a capacitor, and means for supplying a constant voltage to one side of the deflection coil.

[0005]

With the above configuration, the deflection current having good linearity is applied to the deflection coil based on the output voltage of the vertical drive circuit having good linearity and the constant voltage applied to the deflection coil at different vertical frequencies. Can be supplied.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vertical output circuit of a multi-scan monitor according to the present invention will be described in detail below with reference to the drawings. Figure 1
FIG. 6 is a vertical output circuit diagram of a multi-scan monitor according to the present invention. A vertical drive circuit 1 supplies a sawtooth wave current to the vertical deflection coil 2. Reference numeral 3 is a DC negative feedback circuit that corrects the linearity of the output signal of the vertical drive circuit 1. Reference numeral 4 is for connecting a capacitor 5 for DC cut to improve the stability of the vertical drive circuit 1. It is an AC negative feedback circuit. Reference numeral 7 denotes a circuit for connecting a NPN type transistor and a PNP type transistor in a complementary connection, a circuit for connecting a resistor having a first power source grounded to the other side, a resistor, a diode, a diode and a resistor connected in series. , Connect the second power supply to one side and ground the other side,
It is a circuit that supplies a bias voltage to each of the NPN-type and PNP-type transistors, and supplies a constant voltage (V0) 9 to one side 8 of the vertical deflection coil 2 which is approximately half the second power supply.

FIG. 2 is an equivalent circuit of the vertical output circuit (FIG. 1) of the multi-scan monitor according to the present invention. 10 is N
A voltage source equivalent to a circuit 7 for supplying a constant voltage (V0) composed of PN type and PNP type transistors and the like is shown. The vertical drive circuit 1 supplies an output voltage having good linearity to one side of the vertical deflection coil 2 regardless of the vertical frequency used. Since a constant voltage (V0) is supplied to the other side of the vertical deflection coil 2 regardless of the vertical frequency used, the linearity of the sawtooth current supplied to the vertical deflection coil 2 is Holds well.

[0008]

As described above, according to the present invention, by supplying a constant voltage to one end of the vertical deflection coil, DC
Provided that the constants of the negative feedback circuit are determined in one way, a vertical output circuit of a multi-scan monitor that supplies a deflection current with good linearity is provided regardless of the frequency used. Therefore, it is not necessary to change the constant of the DC negative feedback circuit according to the vertical frequency to be used as in the prior art and to correct the linearity of the sawtooth current which causes the top or bottom of the screen to expand or contract. In addition, the impedance is changed according to the vertical frequency to be used, the capacitor that causes the distortion of the sawtooth current is removed, and the conventional method using the vertical drive circuit that requires two positive and negative power supplies is used. The power supply circuit can be used.

[Brief description of drawings]

FIG. 1 is a vertical output circuit diagram of a multi-scan monitor according to the present invention.

FIG. 2 is an equivalent circuit of a vertical output circuit (FIG. 1) of the multi-scan monitor according to the present invention.

FIG. 3 is a conventional vertical output circuit.

FIG. 4 is an equivalent circuit of a conventional vertical output circuit (FIG. 3).

FIG. 5 shows waveforms at various parts of a conventional vertical output circuit.

[Explanation of symbols]

 1 Vertical Drive Circuit 2 Vertical Deflection Coil 3 DC Negative Feedback Circuit 4 AC Negative Feedback Circuit 5 Capacitor for DC Cut 7 Circuit for Supplying Constant Voltage (V0) 8 Vertical Deflection Coil One Side 9 Almost of Second Power Supply Half constant voltage (V0) 10 Equivalent voltage source 20 Vertical drive circuit 21 Vertical deflection coil 22 DC negative feedback circuit 23 AC negative feedback circuit 25 Variable voltage source 30 Voltage waveform 31 Sawtooth current 32 Voltage across capacitor (parabola Voltage) 33 Sawtooth current with good linearity

Claims (2)

[Claims] 1. A vertical drive circuit for amplifying an input signal, a deflection coil connected in series to the output of the vertical drive circuit, a circuit for negatively feeding back the output of the vertical drive circuit by direct current negative, and an output of the vertical drive circuit. A vertical output circuit for a multi-scan monitor, comprising: a circuit for negatively feedbacking AC through the deflection coil and a capacitor; and means for supplying a constant voltage to one side of the deflection coil. 2. The means for supplying the constant voltage is NP
In addition to complement-connecting N-type and PNP-type transistors, a circuit for connecting a resistor to one side of which a power source is grounded, a resistor, a diode, a diode and a resistor are connected in series, and a power source is connected to one side. 2. The vertical output circuit of a multi-scan monitor according to claim 1, further comprising a circuit for connecting the other side to ground and supplying a bias voltage to each of the NPN-type and PNP-type transistors.