Abstract: A display device has a video input unit for inputting video signals from an external device via a signal cable, a video amplifying unit for amplifying the video signals transmitted via the video input unit, and an impedance matching circuit connected between the video input unit and the video amplifying unit, for compensating for the decrease of the video signals. The impedance matching circuit includes: a first resistor connected to the video input unit; a capacitor connected in series with the first resistor and connected to the video amplifying unit; and at least two second resistors connected in series between a connecting point of the first resistor and capacitor and ground.

Abstract: A horizontal position adjusting circuit for a raster includes a reference voltage outputting unit for outputting a reference voltage to enable a raster to be centered on a fluorescent screen; a reference voltage adjusting unit for varying an output voltage of the reference voltage outputting unit in accordance with an operating mode for displaying an image signal; and a deflection voltage outputting unit for generating a deflection voltage in accordance with the output signal of the reference voltage outputting unit, and for applying it to a horizontal deflection coil. In accordance with the present invention, the position of the raster formed on the fluorescent screen of the cathode-ray tube is automatically adjusted according to the operating mode so that positioning of the image screen on the fluorescent screen is simply adjusted to be at the center of the fluorescent screen, resulting in improved reliability of the display device.

Abstract: A linearity correction coil device and a video display apparatus using the same are disclosed. In a video display apparatus having a cathode-ray tube, a deflecting yoke for deflecting the electron beam and a linearity correction coil device for compensating a linearity of the electron beam, the linearity correction coil device is horizontally installed on a printed circuit board for the cathode-ray tube, and wherein a vertical length of said linearity correction coil in an intersecting direction to a progressive direction of the electron beam has a shorter length than a horizontal length of said linearity correction coil device in a parallel direction to the progressive direction of the electron beam. Accordingly, it is able to prevent the electron beam from running off a normal orbit by a magnetic field generated from the linearity correction coil device. Therefore, since the electron beam exactly collides with fluorescent material, it is able to prevent a stained image from showing on the cathode-ray tube.

Abstract: A horizontal size regulation circuit of a horizontal deflection circuit of a display device maintains a constant horizontal size despite transformer manufacturing tolerances, by using a horizontal flyback output value fed back from a choke coil of a horizontal output circuit. A voltage supplied to a switching element providing current to a horizontal output transistor is sensed according to the duty cycle output from a horizontal size controller. A voltage detector incorporated into the horizontal deflection circuit controls the value fed back to the horizontal size controller according to the variation of the voltage supplied to the switching element.

Abstract: A circuit for automatically selecting between the BNC or the D-SUB includes a detector for discriminating a signal currently being input by D-SUB or BNC synchronizing signals input from a computer system. Responsive to a control signal input from the detector, a D-SUB/BNC selecting integrated circuit for generating a predetermined operating signal to either a D-SUB driving circuit or BNC driving circuit.