KR19990003589U - Vertical / horizontal size control circuit of the screen in the monitor - Google Patents

Abstract

The present invention relates to a vertical / horizontal size control circuit for controlling a virtual size horizontal size of a monitor.

According to the present invention, the vertical deflection coil is provided by the vertical / horizontal deflection IC 220 to the vertical deflection part 230 and the horizontal deflection part 240 respectively according to the vertical / horizontal magnitude signal provided by the microcomputer 210. Emitter follower (Q22) for transmitting an increase or decrease in the ABL current of the FBT in a monitor that can adjust the size of the display screen by controlling the current flowing through the V.DY and the horizontal deflection coil H.DY. ; A variable resistor VR1 for adjusting the output of the emitter follower; A first transistor Q21 for varying a vertical size (V.size) signal applied to the vertical / horizontal deflection IC 220 according to a change in an ABL current input through a variable resistor; And a diode D21 for varying a horizontal size (H.size) signal applied to the vertical / horizontal deflection IC 220 according to the change of the ABL current.

The present invention changes the size of the screen according to the change in the ABL current, and as the ABL current increases and the screen becomes larger, the vertical / horizontal size signal is reduced to prevent the screen from becoming larger, and conversely, the screen of the ABL current decreases to decrease the screen. When the size is small, the vertical / horizontal size signal can be increased to prevent the screen from becoming smaller.

Description

Circuit for controlling horizontal / vertical size of display in a monitor

The present invention relates to a virtual size horizontal size control technology of a monitor, and more particularly, to a vertical / horizontal size control circuit of a screen for preventing the size of the screen from being changed according to the brightness of the screen.

In general, CRT beam current (i.e. anode current) varies depending on the brightness of the screen. This is a load change from the FBT point of view, the high voltage of the FBT is changed according to the change of the beam current, and the screen size is changed accordingly. In general, when the screen is dark and the beam current is small, the high voltage becomes high and accordingly, the horizontal size becomes small. On the contrary, when the screen is bright and the beam current increases, the high voltage becomes low and the horizontal size becomes large.

That is, in the CRT, the size of the screen depends on the amount of deflection (the larger the deflection amount, the larger the screen, and the smaller the deflection amount, the smaller the screen). The deflection amount is approximately expressed by the following equation (1).

[Equation 1]

Here, 'B' is the magnitude of the magnetic field, which is proportional to the product of the number of turns of the deflection coil and the current (i _dy ) flowing in the coil, Is the length of the deflection coil, and 'L' is the distance from the deflection point to the fluorescent surface. 'Va' is also the anode voltage of the receiving tube.

When the voltage of the anode is constant in Equation 1, Since L and L are fixed constants, the amount of deflection varies according to 'B', and since the number of turns of the deflection coils also has a fixed constant value, the amount of deflection is usually determined according to the current i _dy flowing in the deflection coil. Therefore, in the horizontal and vertical deflection circuits, a sawtooth current is generated and flows through this deflection coil, thereby deflecting the beam to form a screen.

However, in practice, since the voltage Va of the anode is changed, the amount of deflection changes according to the anode voltage Va. As shown in Equation 1, as the anode voltage increases, the amount of deflection decreases and thus the size of the screen. It becomes smaller, and as the anode voltage decreases, the amount of deflection increases and the screen becomes larger.

At this time, the voltage (high voltage) of the anode of the CRT is expressed as in Equation 2 below.

[Equation 2]

Here, 'Va ₀ ' is the anode voltage when the anode current is '0', 'Rs' is the internal resistance of the CRT, and 'Ia' is the anode current.

Referring to Equations 1 and 2, as the current Ia of the anode increases, the voltage Va of the anode decreases, and as the voltage Va of the anode decreases, the deflection amount increases according to Equation 1 so that the screen is increased. Will increase in size. On the contrary, as the current Ia of the anode decreases, the voltage Va of the anode increases, and as the voltage of the anode increases, the amount of deflection decreases according to Equation 1, thereby reducing the size of the screen.

On the other hand, the general ABL circuit is a circuit for preventing a large anode current from flowing and overloading the component when the brightness is abnormally high. The brightness is controlled by detecting a change in the anode current. ABL is applied by feeding back voltage or contrast control voltage. That is, when the brightness increases and the anode current exceeds the threshold, the anode current is limited by lowering the contrast control voltage of the video preamplifier.

However, the anode current Ia increases when the brightness of the screen becomes bright and decreases when the screen becomes dark, so that the size of the screen changes according to the brightness of the screen. As the node current increases, the screen size increases, and when the screen darkens, the anode current decreases and the screen decreases. Therefore, it is required to prevent the size of the screen from changing according to the brightness of the screen.

Accordingly, the present invention has been made to meet the above necessity, and an object of the present invention is to provide a vertical / horizontal size control circuit of a screen for preventing the size of the screen from fluctuating due to the change of the high voltage.

In order to achieve the above object, the circuit of the present invention provides a vertical deflection coil and a horizontal deflection IC by providing a control signal to the vertical deflection portion and the horizontal deflection portion, respectively, according to the vertical / horizontal magnitude signal provided by the microcomputer. A monitor adapted to control the size of a display screen by controlling a current flowing through a deflection coil, comprising: an emitter follower for transmitting an increase or decrease of an ABL current of an FBT; A variable resistor to adjust the output of the emitter follower; A first transistor for varying a vertical size (V.size) signal applied to the vertical / horizontal deflection IC according to a change in the ABL current input through the variable resistor; And a diode for varying a horizontal size (H.size) signal applied to the vertical / horizontal deflection IC according to the change of the ABL current.

1 is a schematic diagram showing the configuration of a general monitor;

2 is a circuit diagram illustrating a vertical / horizontal size control circuit according to the present invention in a monitor.

* Explanation of symbols for main parts of the drawings

210: micom 220: vertical / horizontal deflection IC

230: vertical deflection portion 240: horizontal deflection portion

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

First, the circuit for adjusting the horizontal and vertical size common in the monitor is to adjust the current flowing in the deflection coil in accordance with the user's key input (user control), as shown in FIG.

Referring to FIG. 1, the horizontal output transistor Q1 is turned on and off according to the horizontal drive signal H. drive to switch the B + voltage applied through the primary winding of the FBT 130 and at the same time, a damping diode Dd. , And sawtooth current flows through the horizontal deflection coil by the action of the retrace capacitor Cr and the horizontal deflection coil Ly. At this time, the S-shaped correction capacitor Cs and the linearity correction coil (not shown) are connected to the horizontal deflection coil Ly to correct the horizontal linearity.

In addition, the H.size signal input from the microcomputer 170 and the pincushion adjustment signal input from the pincushion correction IC (not shown) are connected to the horizontal deflection unit 150 of the diode modulator 160. The horizontal size of the screen can be adjusted by varying the base deflection current by varying the base current of the transistor Q2.

That is, as described above, the size of the horizontal screen is determined by the amount of deflection, and the amount of deflection is changed by the current flowing through the deflection coil, so that the user can adjust the size of the horizontal size (H.size) by user control. When adjusted, the microcomputer 170 outputs an appropriate PWM signal to adjust the current of the horizontal deflection coil to adjust the size of the horizontal screen, and corrects the current flowing in the horizontal deflection coil according to the pincushion signal to increase or decrease the size of the screen. Keep it constant in the middle.

Subsequently, the monitor to which the vertical / horizontal size control circuit according to the present invention is applied, as shown in FIG. 2, the microcomputer 210, the vertical / horizontal deflection IC 220, the vertical deflection unit 230, and the horizontal deflection unit 240. ), A vertical / horizontal size control unit 250. The vertical / horizontal size control unit 250 includes an emitter follower for transmitting an ABL signal, a variable resistor VR21, a first transistor Q21, and a diode D21. A resistor R30 is connected to the base of the second transistor Q22 that implements the emitter follower, the collector is connected to + 12V through the resistor R29, and the resistor R28 is connected between the emitter and the ground. And capacitor C23 are connected respectively. The variable resistor VR21 adjusts the rate at which the output of the emitter follower is delivered to the base of the first transistor, and the emitter of the first transistor is connected to the V.size control terminal through the resistor R25 and the diode D21. Also connected here is a resistor (R24) in series.

The microcomputer 210 provides PWM signals (H.size, V.size) for controlling the vertical size and the horizontal size of the display screen according to a user control (not shown), and receives a vertical / horizontal synchronization signal. Differentiate and control each part of the monitor and provide various control signals. The horizontal size PWM signal (H.size) output from the microcomputer 210 is converted into an analog DC voltage in an integrated circuit composed of a resistor R21 and a capacitor C21, and is then converted into an analog DC voltage through an operational amplifier OP1. It is input to the horizontal size (H.size) terminal of 220. The vertical size PWM signal V.size output from the microcomputer 210 passes through an integrated circuit consisting of a resistor R22 and a capacitor C22 and is vertical to the vertical / horizontal deflection IC 220 through the second transistor Q21. The size (V.size) terminal is entered.

The vertical / horizontal deflection IC 220 is synchronized with the vertical / horizontal synchronization signal input through the desub connector, and the vertical drive signal Vo to be provided to the vertical deflection circuit and the horizontal drive signal H.drive to be provided to the horizontal deflection circuit. Oscillate). The vertical / horizontal deflection IC 220 is also capable of providing a signal for correcting the distortion of the screen, such as pincushion correction, trapezoidal correction, and the like, and a vertical magnitude signal (V.size) input from the microcomputer 210. And a signal for adjusting the vertical / horizontal size of the display screen according to the horizontal size signal (H.size).

The vertical deflection unit 230 supplies the sawtooth wave deflection current to the vertical deflection coil V.DY according to the vertical driving signal provided by the vertical / horizontal deflection IC 220 to make the vertical deflection in the CRT, and the horizontal deflection unit. The 240 is a horizontal deflection in the CRT by supplying a sawtooth deflection current to the horizontal deflection coil (H.DY) in accordance with the horizontal drive signal (H.drive) provided by the vertical / horizontal deflection IC (220).

In the monitor to which the present invention configured as described above is applied, the current of the emitter follower varies according to the ABL current of the FBT, and accordingly, the current flowing through the first transistor Q21 is changed to the original vertical magnitude signal outputted by the microcomputer. A control signal according to the magnitude of the ABL current is added. In addition, when the current of the first transistor Q21 is changed, the emitter side voltage of the first transistor Q21 is changed so that the diode D21 is conducted so that the horizontal size signal H.size is also changed. As such, a magnitude control signal according to the ABL current is added to the original vertical magnitude signal and the horizontal magnitude signal provided by the microcomputer to vary the horizontal magnitude signal and the vertical magnitude signal input to the vertical / horizontal deflection IC 220.

In this case, when the ABL current increases, the size of the screen increases, and when the ABL current decreases, the anode current decreases and the size of the screen decreases. In the vertical / horizontal size control circuit of the present invention, when the ABL current increases, vertical and horizontal By reducing the size signal, the size of the screen is prevented from increasing. On the contrary, when the ABL current decreases, the size of the screen is reduced by increasing the vertical and horizontal size signals.

As described above, when the ABL current changes, the size of the screen also changes accordingly. As the ABL current increases, the screen becomes larger and the vertical / horizontal size signals are reduced to prevent the screen from becoming larger. When the screen is smaller, the vertical / horizontal size signal is increased to prevent the screen from becoming smaller.

Claims (1)

According to the vertical / horizontal magnitude signal provided by the microcomputer 210, the vertical / horizontal deflection IC 220 provides control signals to the vertical deflection unit 230 and the horizontal deflection unit 240, respectively, so that the vertical deflection coil V.DY ), And the monitor screen that can adjust the size of the display screen by controlling the current flowing through the horizontal deflection coil (H.DY), An emitter follower Q22 to convey the increase or decrease of the ABL current of the FBT; A variable resistor VR1 for adjusting the output of the emitter follower; A first transistor (Q21) for varying a vertical size (V.size) signal applied to the vertical / horizontal deflection IC 220 according to a change in the ABL current input through the variable resistor; And The vertical / horizontal size of the screen in the monitor, characterized in that consisting of a diode (D21) for varying the horizontal size (H.size) signal applied to the vertical / horizontal deflection IC 220 according to the change of the ABL current. Control circuit.