KR19990005594A - B + voltage automatic adjustment device and method in monitor - Google Patents

Abstract

The present invention relates to an apparatus and method for automatically adjusting the B + voltage in a monitor for automatically adjusting the B + voltage applied to a high voltage circuit and a deflection circuit of the monitor, wherein the apparatus of the present invention provides a sensing unit 210 for sensing a B + voltage. And a microcomputer 220 which receives the sensing voltage Vs output from the sensing unit 210, compares it with a reference value, and outputs a reference voltage Vref according to the sensing voltage Vs, and the microcomputer 220. And a differential amplifier 230 for differentially amplifying the reference voltage Vref output from the output voltage and the feedback voltage Vb output from the tertiary winding of the FBT 120 and outputting the amplified voltage to the DC-DC converter 140. .

Therefore, the present invention has the effect of improving the reliability and workability by automatically adjusting the B + voltage using a microcomputer when mass-producing the monitor.

Description

B + voltage automatic adjustment device and method in monitor

The present invention relates to an apparatus and a method for automatically adjusting a B + voltage in a monitor for automatically adjusting a B + voltage applied to a high voltage circuit and a deflection circuit of the monitor.

In general, a color cathode ray tube (CRT) used to display information output from a computer is provided with three electron guns to sufficiently amplify the RGB image signal input from the computer through the D sub contactor, and then drives the cathode. The hot electrons emitted from the cathode by heating are passed through the control grid, the screen grid, and the focus grid, and are deflected by the vertical and horizontal deflection magnetic fields so as to collide with the fluorescent surface through the shadow mask to display an image screen.

The deflection circuit and the high voltage circuit of the CRT are typically driven with the same B + voltage, and a diagram for explaining this is shown in FIG. 1.

Referring to FIG. 1, when a horizontal synchronous signal (H.sync) is input from a computer to a horizontal oscillator (not shown), the horizontal oscillator generates a horizontal drive signal (H.drive) of a predetermined frequency, and the horizontal drive signal is After driving in the horizontal driver 100, the horizontal output transistor Q1 of the horizontal output unit 110 is turned on and off.

Meanwhile, the DC voltage supplied from the main power supply (SMPS) 130 is converted by the DC-DC converter 140 to generate the B + voltage. The B + voltage is applied to one end of the primary winding of the FBT 120 and the FBT. Accumulated as current energy during the on operation of the horizontal output transistor Q1 connected to the other end of the primary winding of 120, and then induced into the secondary winding of the FBT 120 during the off operation of the horizontal output transistor Q1.

In this case, a voltage proportional to a turns ratio and an on-off duty ratio of the switching transistor is generated in the secondary winding of the FBT 120. The voltage induced in the secondary winding of the FBT 120 is rectified to reduce the voltage of the CRT. High voltage (HV) and focus (FOCUS) grid and screen grid voltages are applied to the node.

In addition, the voltage induced in the tertiary winding of the FBT 120 is rectified by the diode D1 and smoothed by the smoothing capacitor C1, and then fed back to the DC-DC converter 140, thereby providing the anode terminal of the B + voltage and the CRT. High pressure (HV) is applied to be stabilized.

That is, it should be adjusted to output the correct B + voltage during mass production, and adjust the variable resistor VR1 while reading the B + voltage output from the DC-DC converter 140 with a voltage meter so that the B + voltage matches the reference value. do.

However, the B + voltage adjustment method as described above has a problem in that workability is reduced because of manual adjustment and reliability deteriorates because the B + voltage must be read by a voltage meter.

Accordingly, an object of the present invention is to provide an apparatus and method for automatically adjusting B + voltage in a monitor capable of automatically adjusting the B + voltage, which has been devised to solve the above problems of the prior art.

In order to achieve the above object, the apparatus of the present invention includes a DC-DC converter for converting a direct current output from the main power supply and outputting the B + voltage applied to the FBT, the monitor configured to sense the B + voltage A sensing unit, a microcomputer that receives a sensing voltage output from the sensing unit, compares it with a reference value, and outputs a reference voltage according to the sensing voltage, a reference voltage output from the microcomputer, and a feedback voltage output from the tertiary winding of the FBT. And a differential amplifier configured to differentially amplify and output the DC-DC converter.

In addition, the method of the present invention according to the present invention includes the steps of (A) the microcomputer outputs a reference voltage to the differential amplifier, (B) the sensing unit senses the B + voltage output from the DC-DC converter, (C) The microcomputer receives and reads the sensing voltage output from the sensing unit, and (D) terminates when the sensing voltage is equal to the reference value, increases the reference voltage when the sensing voltage is greater than the reference value, and returns to step (B). And, if the sensing voltage is less than the reference value is characterized in that the step consisting of reducing the reference voltage and then returning to the step (B).

1 is a block diagram showing a B + voltage generation circuit of a typical monitor;

2 is a circuit diagram of a monitor to which the B + voltage automatic adjustment device is applied in the monitor according to the present invention;

3 is a flowchart illustrating a method of automatically adjusting the B + voltage in the monitor according to the present invention.

Explanation of symbols for main parts of the drawings

100: horizontal drive unit 110: horizontal output unit

120: high pressure generating unit (FBT) 130: main power supply (SMPS)

140: DC-DC converter 210: sensing unit

220: Micom 230: differential amplifier

Vs: sensing voltage Vref: reference voltage

Vb: feedback voltage

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a circuit diagram illustrating a part of a monitor to which the B + voltage automatic adjustment device according to the present invention is applied, a horizontal drive unit 100, a horizontal output unit 110, an FBT 120, and a main power supply unit 130. And a DC-DC converter 140 and a B + voltage automatic controller.

Here, the B + voltage automatic adjusting unit receives the sensing unit 210 for sensing the B + voltage and the sensing voltage Vs output from the sensing unit 210, compares the reference value with a reference value, and adjusts the voltage according to the sensing voltage Vs. The DC by differentially amplifying the microcomputer 220 outputting a reference voltage Vref, the reference voltage Vref output from the microcomputer 220 and the feedback voltage Vb output from the tertiary winding of the FBT 120. And comprises a differential amplifier 230 outputting to the DC converter 140.

Looking at the operation and effects of the present invention configured as described above are as follows.

First, the main power supply unit 130 receives a commercial AC power, rectifies and smoothes through a bridge diode (not shown), and outputs a DC voltage.

The DC voltage is input to the DC-DC converter 140 and converted into a B + voltage, and the B + voltage is sensed by the sensing unit 210. In this case, the sensing unit 210 is usually formed of a plurality of resistors for dividing the B + voltage, and is properly divided by the resistors before the sensing voltage Vs is output.

The sensing voltage Vs is input to the microcomputer 220. The microcomputer 220 adjusts the reference voltage Vref after comparing the sensing voltage Vs with a preset reference value. That is, if the sensing voltage Vs is greater than the reference value, the reference voltage Vref is increased than before, and if the sensing voltage Vs is less than the reference value, the reference voltage Vref is decreased before the differential amplifier 230. Will output

On the other hand, the B + voltage output from the DC-DC converter 140 is input to the FBT 120, the high voltage (HV), the focus (FOCUS) grid voltage and the screen (Screen) as the secondary winding of the FBT 120 The grid voltage can be obtained. In addition, the feedback voltage Vref is output through the tertiary winding of the FBT 120.

The feedback voltage Vref is applied to the negative input terminal of the differential amplifier 230, and the reference voltage Vref output from the microcomputer 220 is applied to the positive input terminal of the differential amplifier 230. The differential amplifier 230 amplifies the reference voltage Vref and the feedback voltage Vb at a constant amplification factor and inputs the same to the DC-DC converter 140.

That is, when the voltage difference between the reference voltage Vref and the feedback voltage Vb decreases because the reference voltage Vref decreases, the output voltage of the differential amplifier 230 decreases. As described above, DC-DC When the output voltage of the differential amplifier 230 input to the converter 140 is lowered, the B + voltage is increased while the on-time of the PWM signal becomes longer.

However, if the voltage difference between the reference voltage Vref and the feedback voltage Vb increases due to an increase in the reference voltage Vref, the output voltage of the differential amplifier 230 is increased. As described above, the DC-DC converter ( When the output voltage of the differential amplifier 230 input to 140 increases, the on-time of the PWM signal is shortened and the B + voltage decreases.

3 is a flowchart of a method for automatically adjusting the B + voltage in a monitor according to the present invention.

Referring to FIG. 3, step 31 is a step in which the microcomputer 220 outputs an initial reference voltage, and step 32 is a step in which the sensing unit 210 senses the B + voltage and then outputs the sensing voltage Vs.

In step 33, the microcomputer 220 receives the sensing voltage Vs, and in step 34, the microcomputer 220 reads the sensing voltage Vs and compares the sensing voltage Vs with a reference value. If the sensing voltage Vs is equal to the reference value, the process ends. If the sensing voltage Vs is greater than the reference value, the process proceeds to step 36. If the sensing voltage Vs is less than the reference value, the process proceeds to step 35.

In step 35, the microcomputer 220 reduces and outputs the reference voltage Vref from the initial reference voltage. Then, the microcomputer 220 performs the step 35 and returns to step 32.

Step 36 is a step in which the microcomputer 220 increases the reference voltage Vref after the initial reference voltage and outputs the same, and performs step 36 and returns to step 32.

As described above, the present invention has the effect of improving the reliability and workability by automatically adjusting the B + voltage using a microcomputer when mass-producing the monitor.

Claims (2)

A monitor comprising a DC-DC converter for converting the direct current output from the main power supply to output the B + voltage applied to the FBT, comprising: a sensing unit for sensing the B + voltage and a sensing voltage output from the sensing unit A differential amplifier for differentially amplifying the microcomputer for comparing the reference value with the reference voltage and outputting the reference voltage according to the sensing voltage, the reference voltage output from the micom, and the feedback voltage output from the tertiary winding of the FBT, and outputting the DC-DC converter. In the monitor characterized in that it comprises a B + voltage automatic adjustment device. (A) the microcomputer outputs a reference voltage to the differential amplifier, (B) the sensing unit senses the B + voltage output from the DC-DC converter, and (C) the microcomputer senses the sensing voltage output from the sensing unit. Receiving and reading; and (D) if the sensing voltage is equal to the reference value, and ending; if the sensing voltage is greater than the reference value, increasing the reference voltage and then returning to step (B); if the sensing voltage is less than the reference value, the reference voltage The method for automatically adjusting the B + voltage in the monitor, characterized in that consisting of the step of reducing and then returning to the step (B).