KR19990005560A - Horizontal Deflection Linearity Correction Circuit for Multimode Monitors - Google Patents

Abstract

The present invention relates to a deflection circuit of a monitor, which receives a horizontal frequency output from a video card and outputs a F / V voltage according to the horizontal frequency, and amplifies the control voltage by amplifying the F / V voltage. An amplifying means 20 for outputting, a voltage-current converter 30 for receiving the control voltage and converting the control voltage into a control current I _C , and outputting a horizontal deflection coil HD.Y and a correction capacitor C _S. By providing a horizontal deflection linearity correction circuit of a multimode monitor composed of a variable inductor 40 connected in series and having an inductance variable according to the magnitude of the control current I _C , Therefore, when the horizontal frequency changes from 31 to 75 kHz, the inductance of the variable inductor for adjusting the horizontal linearity of the screen is 4 to 7.5. The image quality is improved because the image is variably adjusted so that the left and right symmetry of the screen can be exactly matched.

Description

Horizontal Deflection Linearity Correction Circuit for Multimode Monitors

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal deflection circuit of a monitor. In particular, a horizontal mode for multi-mode monitors can be improved by changing inductance according to the horizontal frequency variation of each video card supported by a multi-mode monitor. It relates to a deflection linearity correction circuit.

In general, a monitor is a device that receives information from a computer video card and a synchronization signal and displays information on a CRT screen. The monitor includes a video system for processing a video signal, a deflection system for vertical and horizontal deflection, and a power supply. It consists of a system.

Here, the video card is classified into various modes. The classification of the monitor according to the mode of the video card will be described with reference to Table 1 below.

Classification by video mode

Video mode Horizontal frequency (KHz) Vertical frequency (Hz) Resolution (H * V) CGA 15.75 60 640 * 200 EGA 21.8 60 640 * 350 VGA 31.5 60/70 720 * 350 640 * 480 SVGA 35 to 37 INTERLACE 1024 * 768 High resolution mode 64 to 75 60 to 70 1024 * 7681280 * 1024

That is, the video mode outputs a horizontal frequency and a vertical frequency differently according to the resolution to be implemented. As the vertical frequency increases from a low frequency to a high frequency, screen flicker is prevented, thereby reducing eyestrain of users. .

Here, the multi-mode monitor is a monitor that is compatible with at least two video modes, and changes the size and position of images according to various horizontal frequencies (about 30 to 75 KHz) output from the video card, horizontal and vertical synchronization, and This means that the monitor can be used to optimize the deflection unit and to adjust various deflection correction circuits.

Before describing the horizontal deflection circuit of the multi-mode monitor, the deflection principle of a general monitor is as follows. The electron beam emitted from the cathode of the monitor is accelerated through the grid, and moves the light spot of the fluorescent surface by changing its course by the electromagnetic action of the magnetic field of the deflection coil.

At this time, the deflection distance of the electron beam is proportional to the strength of the magnetic field, and the magnetic field uses the principle of electron deflection, which is proportional to the current of the deflection coil. In order to return to, the horizontal deflection coil for moving the light point in the horizontal direction (left and right) and the vertical deflection coil for moving the light point in the vertical direction (up and down) are used.

That is, a sawtooth current as shown in FIG. 1 flows through the horizontal deflection coil, and at the point a of the sawtooth current, a force that deflects the electron beam to the leftmost direction acts on the electron beam, and at the point b, the current Does not flow, the electron beam goes straight.

In addition, at point b, the current that causes the electron beam to bend to the right gradually increases, and at point c, the electron beam is deflected to the right, and the current rapidly decreases, and the above process is repeated from point a '.

FIG. 2 illustrates a horizontal deflection circuit of a monitor generating the sawtooth wave current as described above. The horizontal synchronizing signal output from a video card (not shown) is a horizontal drive signal (H.drive) at a horizontal oscillator (not shown). The signal is properly modulated and supplied to the horizontal driving transistor TR1.

The horizontal driving signal H.drive turns on the horizontal driving transistor TR1 and conducts the driving power supply Vcc, the horizontal driving transistor TR1 and the horizontal driving transformer HDT to the base of the horizontal output transistor TR2. Supply current to the terminal.

At this time, when the horizontal output transistor TR2 is turned on, the B + power current of the flyback transformer (not shown) flows to the horizontal output transistor TR2 through the horizontal deflection coil HD.Y.

While the horizontal output transistor TR2 is turned on as described above, it corresponds to the second half of the effective syringe of the sawtooth wave (that is, between the point b and the point c), and the horizontal output transistor TR2 according to the horizontal drive signal H.drive. Is rapidly turned off, the current accumulated in the horizontal deflection coil (HD.Y) charges the retrace capacitor (RE.C).

In this case, when the retrace capacitor RE.C is fully charged, the discharge capacitor discharges back to the horizontal deflection coil HD.Y, and accordingly, current is accumulated in the horizontal deflection coil HD.Y.

At this time, the period between the charging and discharging of the retrace capacitor is a period corresponding to the retrace period (that is, between c point and a 'point).

In addition, when the energy is accumulated in the horizontal deflection coil HD.Y as described above, and the deflection coil voltage is such that the forward bias is applied to the damper diode DD, the damper diode DD is conducted and the horizontal deflection coil HD is applied. The current flowing in .Y) drops to zero.

At this time, the period in which the current flows through the damper diode D.D corresponds to the first half of the effective syringe of the sawtooth wave (that is, between point a and point b).

As described above, the horizontal output transistor TR2 is turned on again by the horizontal drive signal H.drive when the current flowing in the horizontal deflection coil HD.Y becomes zero, and the above process is repeated. The saw-tooth wave current flows through the horizontal deflection coil HD.Y so that the horizontal deflection of the electron beam is achieved.

However, as shown in FIG. 3B, when the complete sawtooth current shown in FIG. 3A flows through the horizontal deflection coil HD.Y, a non-linear phenomenon of the screen horizontal width occurs. Since the distance from the center of the HD.Y becomes longer toward the edge of the fluorescent screen, the amount of change in the horizontal deflection angle of the horizontal deflection coil HD.Y is constant on the screen object. ( )

Therefore, in order to improve the linearity of the screen as shown in FIG. 3D, the S-shaped sawtooth wave as shown in FIG. 3C must be flowed to the horizontal deflection coil HD.Y. A horizontal deflection linearity correction circuit 50 for generating a is connected in series with the horizontal deflection coil HD.Y as shown in FIG.

That is, the horizontal deflection linearity correction circuit 50 includes a horizontal linear coil L _S and a correction capacitor C _S connected in series with the horizontal deflection coil HD.Y, and the horizontal linear coil L _S. It consists of a resistor (R) and a capacitor (C) connected in parallel to the bar, the horizontal deflection linearity correction circuit 10 configured as described above and oscillate by forming a series and parallel resonant circuit with the retrace capacitor (RE.C) Generates an appropriate sigmoidal sawtooth current.

In this case, the horizontal linear coil (L _S ) is adjusted so that the horizontal width of the screen is symmetrical, the correction capacitor (C _S ) to compensate the S sawtooth wave current to prevent the left and right of the horizontal scan, the resistance (R) ) And the capacitor C remove noise, and the inductance of the horizontal linear coil L _S and the capacitance of the correction capacitor C _S determine the oscillation frequency and magnitude of the sawtooth current.

When the S-shaped sawtooth current determined as described above flows to the horizontal deflection coil HD.Y, the screen horizontal width and linearity are corrected by deflecting the electron beam according to the strength of the magnetic force generated in proportion to the magnitude of the sawtooth current.

Here, the horizontal linear coil (L _S ), which is a factor for determining the horizontal width of the screen, can be obtained by winding a conductive wire around a permanent magnet, and has the characteristics as shown in FIG. 4, and the inductance when a sawtooth wave does not flow is constant. It is fixed to a value, so that the inductance increases rapidly while the sawtooth current is in the positive period, and decreases slowly while the sawtooth current is in the negative period. As described above, while the inductance is changed to the S-shape, the screen is equally balanced with the distance of the screen left and right from the center of the screen of the monitor.

However, the horizontal linear coil L _S can be suitably applied to a single mode monitor because the inductance of the sawtooth current is not fixed. However, the horizontal linear coil L _S can be applied to a multi mode monitor designed to realize various modes. There is a problem that cannot be done.

In other words, when a multi-mode monitor capable of implementing VGA, SVGA and high resolution modes is input with various horizontal frequencies of 31 to 75 kHz, the inductance of the horizontal linear coil L _S when no sawtooth current flows is 4 to 7.5. Since the inductance of the horizontal linear coil L _S is fixed, there is a problem in that an unbalanced phenomenon occurs in a screen in which the distance of the screen left and right from the center of the screen is changed.

Accordingly, the present invention has been made to solve the above problems, the image quality is improved by improving the unbalance of the screen by varying the inductance of the horizontal linear coil (L _S ) in accordance with the horizontal frequency variation of each mode in the multi-mode monitor It is an object of the present invention to provide a horizontal deflection linearity correction circuit for a multimode monitor.

Horizontal deflection linearity correction circuit for a multi-mode monitor according to the present invention for achieving the above object is a microcomputer receiving the horizontal frequency output from the video card and outputs the F / V voltage according to the horizontal frequency, and the F / An amplifying means for amplifying a V voltage and outputting a control voltage, a voltage-current converter for receiving the control voltage and converting the control voltage into a control current, and a series connection between a horizontal deflection coil and a correction capacitor and a magnitude of the control current. In accordance with the inductance is characterized by consisting of a variable inductor.

1 is a graph of the sawtooth current;

2 is a circuit diagram illustrating a horizontal deflection circuit for a monitor to which a conventional horizontal deflection linearity correction circuit is applied;

3 is a diagram showing the necessity of a horizontal deflection linearity correction circuit for a monitor;

3a is a graphical representation of a complete sawtooth current;

3b is a plan view showing a non-linear state of the screen horizontal width when a complete sawtooth current flows through the deflection coil;

3C is a graph of the S-shaped sawtooth current;

3d is a plan view showing a linear state of a screen horizontal width when an S-shaped sawtooth current flows through a deflection coil;

4 is a graph showing a change in inductance of a correction coil;

5 is a circuit diagram showing a horizontal deflection linearity correction circuit for a multi-mode monitor according to the present invention;

6 is a graph illustrating a change in inductance of the variable inductor according to the change of the control current.

Explanation of symbols for main parts of the drawings

10: micom 20: amplification means

21: Op amp 22: Reference voltage capacitor

23: feedback resistance 30: voltage-to-current converter

31: transistors 32,33,34: noise canceling capacitor

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

5 shows a horizontal deflection circuit of a multimode monitor to which a horizontal deflection linearity correction circuit is applied according to the present invention, wherein the horizontal deflection linearity correction circuit of the multimode monitor according to the present invention inputs a horizontal frequency output from a video card. A microcomputer 10 for receiving the F / V voltage according to the horizontal frequency, an amplifying means 20 for amplifying the F / V voltage and outputting a control voltage, and a control current I _{C for} receiving the control voltage. ) Is connected in series between the voltage-current converter (30) and the horizontal deflection coil (HD.Y) and the correction capacitor (C _S ) and converts the output current into a variable voltage according to the size of the control current (I _C ). Consisting of a variable inductor 40.

Here, the amplifying means 20 is connected between the op amp 21, the F / V voltage is input to the non-inverting input terminal, and the non-inverting input terminal and the inverting input terminal of the op amp 21 is the inverting input A reference voltage capacitor 22 which provides a reference voltage to a terminal, a feedback resistor 23 connected between an output terminal of the op amp 21 and an inverting input terminal, and a driving power to be divided to the non-inverting input terminal. The first voltage divider resistor 24 and the second voltage divider resistor 25 are provided.

In addition, the voltage-current converter 30 includes a transistor 31 for changing the base current according to the control voltage output from the amplifying means 20 and outputting the control current I _C to the emitter stage, and the transistor ( A first noise canceling capacitor 32 for removing the noise component included in the base current of the transistor 31 and a second noise canceling capacitor 33 for removing the noise component included in the emitter current of the transistor 31. And a third noise removing capacitor 34 for removing noise components contained in the collector current of the transistor 31.

Finally, the variable inductor 40 includes a primary coil through which a sawtooth current flows, a secondary coil through which a control current I _C output from the emitter terminal of the transistor 31 flows, and the primary coil and the secondary side. The coil is formed of a magnetic core wound around the inductance so that the inductance is varied according to the magnitude of the sawtooth current and the control current I _C.

Next, the operation and effects of the apparatus according to the present invention configured as described above are as follows.

Prior to describing the present invention, a process of outputting the horizontal drive signal H.drive input to the horizontal drive transistor TR1 in FIG. 2 will be described briefly. As shown in Table 1, the video card is implemented accordingly. Output various horizontal frequencies (H.sync) according to the video mode you want to use.

At this time, the microcomputer 10 receives the horizontal frequency (H.sync) from the video card and outputs an F / V voltage in the form of PWM (Pulse Width Modulation) corresponding to the horizontal frequency (H.sync), PWM The / DC converter converts the F / V voltage back to a DC voltage having a constant magnitude and outputs the DC voltage to the horizontal oscillator. The DC converter receives the DC voltage from the horizontal oscillator to generate a horizontal drive signal (H.drive).

In the present invention, as described above, the F / V voltage output from the microcomputer 10 is used, and the F / V voltage is output at a value proportional to the horizontal frequency.

The F / V voltage output from the microcomputer 10 is properly amplified by the op amp 21, which is a non-inverting amplifier, and the op amp 21 outputs a control voltage. The base current of 31) is varied.

In addition, when the base current changes, the emitter current of the transistor 31 also varies, and the control current I _C , which is the emitter current, flows to the secondary coil of the variable inductor 40.

In this case, the control current I _C flows in the direction of decreasing the inductance of the variable inductor 40. When the size of the control current I _C increases, the inductance of the variable inductor 40 decreases. As the magnitude of the current I _C decreases, the inductance increases.

Here, the operation of the amplifying means 20 and the voltage-current converter 30 are as follows.

First, the amplifying means 20 is a driving power is divided by the first voltage divider 24 and the second voltage divider 25, the voltage applied to the second voltage divider 25 is the reference voltage capacitor 22 The voltage is divided by the auxiliary resistor, and the reference voltage is accumulated in the reference voltage capacitor 22 so that the op amp 21 always has a positive output signal even when the F / V voltage is not input.

In the above state, when the F / V voltage is input to the non-inverting input terminal of the op amp 21, the control voltage is output after the F / V voltage is properly amplified, which is the voltage of the F / V voltage. This is because the F / V voltage must be amplified so as to be recognized by the voltage-current converter 30 because it cannot be recognized by the DC converter 30.

As described above, the control voltage output after the amplification of the F / V voltage is applied to the base end of the transistor 31 of the voltage-current converter 30, and the potential of the base end of the transistor 31 is the emitter end. More than 0.7V, the transistor 31 is turned on, and the base current of the transistor 31 is amplified by an amplification factor to flow to the emitter stage.

That is, the base current in proportion to the magnitude of the control voltage flows, and the emitter current in proportion to the base current flows, so that the emitter current becomes the control current I _C and the secondary coil of the variable inductor 40. And the inductance of the variable inductor 40 is varied by the control current I _C.

At this time, since the noise component induced from the primary coil to the secondary coil of the variable inductor 40 is bypassed by the first, second, and third noise canceling capacitors 32, 33, and 34, the DC component is controlled. Current I _C flows to the secondary coil of the variable inductor 40.

FIG. 6 is a diagram illustrating a change in inductance of the variable inductor 40 according to the sawtooth wave current and the control current, in which the S-shaped inductance change occurs and the size of the control current I _C according to the change of the sawtooth wave current As a result, the inductance increases or decreases as a whole.

That is, when a low frequency horizontal frequency is input from the video card, the microcomputer 10 outputs a low voltage F / V voltage, and the amplifying means 20 outputs a low voltage control voltage and the voltage-current converter 30. Outputs a low current control current I _C so that the inductance of the variable inductor 40 becomes relatively high.

However, when a video mode is converted from a low resolution to a high resolution and a high frequency horizontal frequency is input from the video card, the microcomputer 10 outputs a high voltage F / V voltage, and the amplifying means outputs a high voltage control voltage. The voltage-current converter 30 outputs a high current control current I _C so that the inductance of the variable inductor 40 is lowered.

As described above, in the device of the present invention, when the horizontal frequency changes from 31 to 75 kHz according to the mode to be implemented in the multi-mode monitor, the inductance of the variable inductor for adjusting the horizontal linearity of the screen is 4 to 7.5. The image quality is improved because the image is variably adjusted so that the left and right symmetry of the screen can be exactly matched.

Claims (5)

A microcomputer 10 for receiving a horizontal frequency output from a video card and outputting an F / V voltage according to the horizontal frequency, an amplifying means 20 for amplifying the F / V voltage and outputting a control voltage, and the control A voltage-current converter 30 that receives a voltage and converts it into a control current I _C and outputs it in series, and is connected in series between a horizontal deflection coil HD.Y and a correction capacitor C _S , and the control current I _C ) A horizontal deflection linearity correction circuit for a multi-mode monitor, characterized in that consisting of a variable inductor 40 inductance is variable according to the size. 2. The amplifying means (20) according to claim 1, wherein the amplifying means (20) is connected between an op amp (21) in which an F / V voltage is input to a non inverting input terminal, and is connected between a non inverting input terminal and an inverting input terminal of the op amp. A horizontal deflection linearity correction circuit for a multi-mode monitor, comprising a reference voltage capacitor 22 providing a reference voltage as an input terminal, and a feedback resistor 23 connected between an output terminal of the op amp and an inverting input terminal. . According to claim 1, wherein the voltage-to-current converter 30 is a transistor 31 that changes the base current in accordance with the control voltage output from the amplifying means 20 and outputs the control current (I _C ) to the emitter stage Horizontal deflection linearity correction circuit of a multi-mode monitor characterized in that configured. The method of claim 3, wherein the voltage-current converter 30 is a first noise removing capacitor 32 for removing the noise component included in the base current of the transistor 31 and the emitter current of the transistor And a second noise canceling capacitor (33) for removing the noise component included therein, and a third noise canceling capacitor (34) for removing the noise component included in the collector current of the transistor. Horizontal deflection linearity correction circuit in mode monitor. The variable inductor 40 of claim 1, wherein the variable inductor 40 includes a primary coil through which a sawtooth current flows, a secondary coil through which a control current I _C output from the voltage-current converter, and a primary coil; The horizontal deflection linearity correction circuit of the multi-mode monitor, characterized in that the inductance is varied according to the magnitude of the sawtooth current and the control current, wherein the differential coil is wound around the magnetic core.