KR970005650Y1 - Screen stabilizing circuit to control grid voltage - Google Patents

Abstract

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Description

Screen stabilization circuit with grid voltage

1 is a conventional image processing circuit diagram

2 is a screen stabilization circuit diagram of the grid voltage of the present invention

3 is a graph showing the relationship between horizontal frequency and voltage

* Description of the symbols for the main parts of the drawings *

1: video signal output unit 2: cathode ray tube

3: screen brightness adjustment unit 4: F / V conversion unit

5 Comparative Unit 6: Differentiation

7: switching unit 10: buffer unit

The present invention relates to a screen stabilization circuit, and in particular, to compose a comparator and to adjust a grid voltage by comparing an input frequency voltage with a reference voltage to solve a transient state in which screen synchronization is broken.

As shown in FIG. 1, the conventional video signal processing circuit includes a video output unit 1 for outputting a video signal, and a video signal output from the video signal output unit 1 to the cathode ray tube 2; A buffer unit 10 for outputting to the cathode terminal K, a cathode ray tube 2 for displaying an image signal output from the buffer unit 10, and a grid terminal G1 of the cathode ray tube 2; It consists of a screen brightness control unit 3 for adjusting the brightness of the screen.

Reference numeral C3 denotes a capacitor, and R7 and R8 denote resistors.

The operation of the conventional video signal processing circuit configured as described above is performed when the video signal is output from the video signal output unit 1, as shown in FIG. 1. In the condenser C3 of the buffer unit 10, the video signal output unit 1 Only the signal of the pure AC component of the video signal output from the output to the cathode terminal (K) of the cathode ray tube (2), the cathode ray tube (2) by the signal output from the condenser (C3) to display the image signal In this case, the voltage of the cathode ray tube 2 and the grid terminal G1 is adjusted by the screen brightness adjusting unit 3.

However, in the conventional video signal processing circuit, when a frequency higher than the operating frequency is input, the output of the video signal has a problem in that the cathode ray tube 2 displays a screen in which the synchronization is unstable or unstable.

In order to solve such a conventional problem, the present invention is designed to stabilize the screen in an unstable state by adjusting a grid voltage of a cathode ray tube by comparing a frequency voltage input by configuring a comparator with a reference voltage. The configuration and the effect of the operation are as follows.

The screen stabilization circuit for adjusting the grid voltage according to the present invention includes a video signal output unit 1 for outputting a video signal and a video signal output from the video signal output unit 1 as shown in FIG. The screen brightness of the cathode ray tube (2) and the cathode ray tube (2) which displays the buffer unit (10) output to the cathode terminal (K) of (2), and the image signal output from the buffer unit (10) In the screen brightness adjusting unit 3 for adjusting, the frequency (F) / voltage (V) converting unit 4 for converting and outputting the input horizontal frequency fH into voltage, and the F / V converting unit 4 The comparator 5 for comparing the output voltage with the reference voltage, the differentiator 6 for differentiating and outputting the signal output from the comparator 5, and the signal output from the differentiator 6 It is composed of a switching unit (7) for outputting the sub-bias voltage input from the flyback transformer (FBT) to the grid terminal of the cathode ray tube (2) .

The comparator 5 includes a bias resistor R1 and R2 and a comparator A1 for comparing the voltage output from the F / V converter 4 with a reference voltage, and the differentiator 6 is a differential loop. And a capacitor C1 and a resistor R3 forming a LOOP, and the switching unit 7 is differentiated by the voltage divider resistors R4 and R5 and the capacitor C1 and the resistor R3. The output signal is composed of a transistor Q1 that switches on / off by a voltage distributed through the voltage divider resistors R4 and R5.

Reference numerals R6, R7 and R8 are resistors, C2 and C3 are capacitors, and D1 is a diode.

As shown in FIG. 2, the F / V converter 4 detects an input horizontal frequency fH and converts the voltage into a voltage as shown in FIG. 2. As shown in the drawing, when the horizontal frequency (fH) is inputted at 31 KHz, the F / V converter (4) outputs a 2V voltage, and when the horizontal frequency (fH) is input at 48KHz, the 4V voltage is output, and the horizontal frequency (fH) is 64KHz. Is input, the F / V converter 4 outputs a 6V voltage.

When the operating frequency is 48KHz, the reference voltage becomes 4V. When the horizontal frequency fH is inputted to 64KHz, the F / V converter 4 outputs 6V as shown in FIG. 3 and converts the F / V. The 6V voltage output from the unit 4 is input to the comparator A1 via the bias resistor R1.

The comparator A1 of the comparator 5 outputs a high voltage in comparison with the reference voltage 4V, and the derivative of the comparator A1 is composed of the capacitor C1 and the resistor R3 of the differentiator 6. Is differentiated by the circuit and applied to the base of the transistor Q1 of the switching unit 7, so that the transistor Q1 is turned on by the differential signal of the differentiator 6 and is input from the full-back transformer FBT. Is applied to the grid terminal G1 of the cathode ray tube 2 to adjust the grid voltage of the cathode ray tube 2 to display the image signal output from the image signal output unit 1 at the cathode ray tube 2 to display the cathode ray tube ( By generating a mute phenomenon on the screen of 2), it is possible to prevent a transient phenomenon that the screen synchronization is broken.

On the other hand, when the operating frequency is 48Hz, when the horizontal frequency fH is 31KHz input, the F / V converter 4 outputs 2V as shown in FIG. 3 and inputs it to the comparator A1, and the F / V converter When the low signal is output by comparing the 2V voltage output from (4) and the reference voltage 4V by the comparator A1, the derivative is differentiated in the differential circuit composed of the capacitor C1 and the resistor R3 to the base of the transistor Q1. Since the transistor Q1 is turned off by the signal applied and differentiated in the differentiator 6, the -100V input from the flyback transformer FBT is prevented from being applied to the grid terminal G1 of the cathode ray tube 2. The video signal output from the signal output unit 1 is normally displayed in the cathode ray tube 2.

As described above, the present invention configures the comparator 5 to adjust the grid voltage of the cathode ray tube 2 in comparison with the reference voltage when the horizontal frequency fH greater than the operating frequency is input. By zooming in, a transient phenomenon generated when a horizontal frequency fH larger than the operating frequency is input is improved.

Claims (2)

An F / V converter for converting and outputting an input horizontal frequency fH into a voltage, a comparator for comparing the voltage output from the F / V converter with a reference voltage, and differentiating a signal output from the comparator And a switching unit configured to output a differentiator to be output by the signal output from the differentiator and output a negative bias voltage input from the flyback transformer (FBT) to the grid terminal of the cathode ray tube. Grid) Screen stabilization circuit with voltage control. The method of claim 1, wherein the comparator comprises a bias resistor, a comparator for comparing a voltage output from the F / V converter and a reference voltage, and the differential is composed of a capacitor and a resistor forming a differential loop (LOOP). The switching unit adjusts a grid voltage, characterized in that consisting of a transistor for switching the voltage divided by the capacitor and the resistor is divided on and off by the voltage divided through the voltage divider resistor. One screen stabilization circuit.