KR940007991B1 - Vertical dynamic focus circuit - Google Patents

Abstract

The frequency discriminating vertical dynamic focusing circuit includes a parabolic waveform generator for receiving the output signal of a vertical outputting portion and generating a parabolic waveform, an inversion amplifier for invertedly amplifying the vertical dynamic focusing waveform of a vertical focusing portion, a vertical frequency/voltage converter for converting the frequency of the vertical sync signal to a voltage, a comparator for comparing the output voltage with other set voltages, and an analog switch for operating variable resistors to make uniform the output voltage of the amplifier, thereby enhancing quality of picture.

Description

Frequency Discrimination Vertical Dynamic Focus Circuit

1 is a conventional vertical dynamic focus circuit diagram.

2 is a waveform diagram of each part according to the prior art.

3 is a frequency discriminating vertical dynamic focus circuit diagram of the present invention.

4 is a characteristic graph of vertical-frequency / voltage according to the present invention.

5 is an analog switch connection characteristics table according to the present invention.

* Explanation of symbols for main parts of the drawings

1: vertical output unit 2: parabolic waveform generator

3: inverted amplification part 4: vertical focus part

5: vertical-frequency / voltage converter 6, 7: first and second comparison unit

8: Analog switch part R1-R12: Resistance

VR1-VR3: Variable resistor C1-C5: Capacitor

Q1, Q2: Transistor OP1, OP2: Operational Amplifier

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical dynamic focus circuit, and in particular, to determine a vertical dynamic focus waveform voltage magnitude as a vertical frequency so as to have a constant voltage magnitude in each mode, thereby adjusting the focus in each mode to the best. It relates to a frequency discriminating vertical dynamic focus circuit suitable for improving picture quality.

In the conventional vertical dynamic focus circuit, as illustrated in FIG. 1, a vertical output unit in which a signal input through a vertical IC and a vertical deflection coil V-DY is output by a capacitor C1 and a ground resistor R1 ( 1), the parabola waveform generator 2 in which the signal output from the vertical output unit 1 is integrated by the resistors R2 and R3 and the ground capacitor C2 and C3 and output as a parabolic waveform; An inverted amplifier 3 in which the parabola waveform is inverted and amplified by the transistors Q1, Q2 and the resistors R4-R7 and the capacitor C4 in the parabola waveform generator 2, and the inverted amplifier The parabola waveform amplified in (3) is composed of a vertical focus portion 4 which is input by AC coupling with a resistor R8 and a capacitor C5.

In the prior art operation configured as described above, the input signal is output as a waveform as shown in FIG. 2A at the secondary side of the vertical deflection coil V-DY of the vertical output unit 1 and one connection point a of the capacitor C1. The parabolic waveform b is generated as shown in b of FIG. 2 by integrating with the resistors R2 and R3 and the ground capacitors C2 and C3. This parabola waveform is applied to the base of the transistor Q1 and is converted from the inverted amplifier 3 by the transistors Q1 and Q2 and the resistors R4 and R7 and the capacitor C4 to the waveform c as shown in FIG. Where the magnitude of the voltage V3 of the point C waveform is determined by the magnitude of the divided voltage by the resistors R5 and R6 applied to the base of the transistor Q2 and the voltage magnitude V2 of the point B waveform. (V3) The size is determined.

Accordingly, the waveform c, which is inverted and amplified in this manner, is AC-coupled to the resistor R8 and the capacitor C5 and operated as a vertical dynamic focus waveform in the vertical focus unit 4.

However, in the conventional vertical dynamic focusing circuit, when the AC voltage V1 is multi-mode in the A-point waveform, it varies depending on the vertical frequency and the vertical size for each mode, so that the B point applied to the base of the transistor Q1 is applied. The voltage magnitude V2 of the waveform is different and the voltage magnitude V3 appearing at point C is different when the DC voltage applied to the base of the transistor Q2 is constant by the resistors R5 and R6.

Accordingly, there is a problem in that the vertical dynamic focus voltage magnitude is different for each mode in the multi mode, so that the vertical focus state of the display screen is not constant and worse in some modes.

The present invention provides a frequency discriminating vertical dynamic focus circuit that can determine and adjust a vertical frequency in a multi-mode monitor and adjust the dynamic focus voltage for each mode to create a constant voltage level in each mode. The invention is described with reference to the accompanying drawings as follows.

3 is a frequency discrimination vertical dynamic focus circuit diagram of the present invention, as shown here, a vertical output unit 1 for outputting a signal according to a vertical frequency and a size of a vertical screen size, and an output signal of the vertical output unit 1. Parabola waveform generator 2 for integrating and outputting the parabola waveform, an inverted amplifier 3 for inverting and amplifying the signal output from the parabola waveform generator 2, and outputted from the inverted amplifier 3 In a vertical dynamic focusing circuit composed of a vertical focusing unit (4) for alternating an AC signal to adjust the vertical dynamic focus, the vertical-frequency / vertical frequency (V-SYNC) frequency is converted into a voltage and output. The voltage Va and the voltage set by the resistors R9 and R10 in the respective operational amplifiers OP1 and OP2 are converted into voltages 5 and the voltages output from the vertical-frequency / voltage converter 5. By R11) (R12) Operation is performed in accordance with the first and second comparison units 6 and 7 for comparing and outputting the set voltage Vb and the output voltages A0 and A1 compared in the first and second comparison units 6 and 7. Since the terminal Z0 is operated by switching to the fixed terminals Y0, Y2 and Y3 and the fixed terminal Y1 connected to the respective ground variable resistors VR1 to VR3, the transistors in the inverting amplifier 93 are operated with the corresponding voltages. It comprises a analog switch unit (8) for setting a base voltage of (Q2) to adjust a constant voltage for each mode.

The operation and effect of the present invention configured as described above will be described with reference to the vertical-frequency / voltage characteristic graph of FIG. 4 and the analog switch connection characteristic table of FIG.

First, the waveform a output from the vertical output unit 1 is integrated in the parabola waveform generating unit 2 and output as the parabola waveform b, and then applied to the base of the transistor Q1 of the inverting amplifier 3. The waveform c inverted and amplified from the collector of transistor Q2 to which the emitter is connected to the collector of Q1) is output.

At this time, since the magnitude of the voltage V1 in the waveform of point A is different in each mode, when the voltage V2 of the point B waveform applied to the base of the transistor Q1 is different, the base voltage of the transistor Q2 is constant. The magnitude of voltage V3 at point C is different.

Accordingly, the present invention uses the vertical-frequency / voltage converter 5 for converting the vertical synchronization signal V-SYNC into the frequency voltage to vary the driving voltage applied to the base of the transistor Q2 according to the vertical frequency. .

In this case, when the output voltage of the vertical-frequency / voltage converter 5 is output as V5 voltage at 50 Hz, V6 voltage at 60 Hz, and V7 voltage at 70 Hz as shown in FIG. The reference voltage of the inverting terminal (-) of the amplifier OP1 sets the voltage Va corresponding to the F / V voltage having a vertical frequency of 55 Hz with the resistors R9 and R10 and is calculated by the second comparator 7. The reference voltage of the inverting terminal of the amplifier OP2 sets a voltage Vb corresponding to an F / V voltage having a vertical frequency of 65 Hz with the resistors R11 and R12.

Accordingly, when the output of the vertical-frequency / voltage converter 5 is input to the non-inverting terminals of the operational amplifiers OP1 and OP2, it is compared with the set voltage of the inverting terminal of each comparator as shown in FIG. The outputs A0 and A1 of the first and second comparison parts 6 and 7 are outputted, and the channel connection of the analog switch part 8 is made by the input signals A0 and A1 as shown in FIG. If the vertical frequency is 50Hz, Z0-Y0 is connected to operate the variable resistor (VR1), and at 60Hz, Z0-Y2 is connected to the variable resistor (VR2), and at 70Hz, Z0-Y3 is connected to the variable resistor. VR3 is operated so that the voltage divided by the resistor R5 and the variable resistors VR1 to VR3 is applied to the base voltage of the transistor Q2 of the inverting amplifier 3.

Therefore, the base voltage of the transistor Q2 is set differently for each frequency so that the V1 size of A point in each mode is different, so that the V3 of the vertical dynamic focus voltage output waveform is constant in each mode in the vertical focus unit 4. . That is, when the V1 size of the point A is smaller than other modes, the base voltage of the transistor Q2 is made higher, and the base voltage of the transistor Q2 is lowered in the mode where the size of V1 of the point A is larger, so that the voltage in each mode is reduced. Adjust the size of (V3) constantly.

As described in detail above, the present invention improves the dynamic focus characteristics in each mode by allowing the voltage magnitude of the vertical dynamic focus waveform of the multi-mode monitor to be the voltage level of the constant dynamic focus waveform in each mode according to the vertical frequency discrimination. The effect is to increase the quality.

Claims (1)

A parabolic waveform generator 2 for receiving and integrating the output signal of the vertical output unit 1 according to the vertical frequency and the size of the vertical screen size to generate a parabola waveform; An inverting amplifier 3 for inverting and amplifying the vertical dynamic focus waveform to be adjusted; a vertical-frequency / voltage converter 5 for converting a frequency of the vertical synchronization signal into a voltage; The first and second comparators 6 and 7 which Va (Vb) compares and outputs the respective variable resistors VR1-VR3 set by discriminating the vertical frequency according to the compared voltages A0 and A0. A frequency discriminating vertical dynamic focusing circuit, characterized in that it comprises an analog switch section (8) which operates to make the output voltage level of the inverting amplifier section (3) constant in each mode.