Abstract A monitor-mode control circuit and method thereof determines a video mode by detecting horizontal and vertical sync frequencies and the polarities of the sync frequencies received from a video card, varies an external resistance value connected to a predetermined port of a microprocessor in accordance with the determined video mode to output a voltage for controlling the picture status of the monitor, in which a program of the microprocessor is changed by a demand of a buyer without changing the hardware to easily correspond to any specification required by the buyer unrestricted by the specification, an external resistance value connected to the predetermined port of the microprocessor at a high or low state is varied to adjust and output voltages of a horizontal size, a vertical size, a horizontal position, a vertical position and a side pin/barrel corresponding to the determined video mode, and a voltage of an oscillating frequency for correcting the synchronization of a picture is output by a pulse width modulation method, so that manufacturing cost is reduced without using a D/A converter of an EEPROM to heighten the competitive power of the products.
A monitor-control method comprising the steps of: detecting horizontal and vertical sync frequencies and polarities of horizontal and vertical sync signals input from a video card; determining, in a microprocessor, a video mode of said video card, using the detected horizontal and vertical sync frequencies and polarities; producing an oscillating voltage in accordance with corresponding horizontal and vertical sync frequencies by pulse width modulation in which said horizontal and vertical sync frequencies are divided into predetermined levels; outputting a high or low signal, simultaneously while outputting said oscillating voltage, by selecting a respective one of a plurality of ports of a picture control terminal of said microprocessor in accordance with the determined video mode, thereby adjusting a voltage of a signal supplied to said picture control terminal, and connecting resistors to said ports in parallel to each said picture control terminal associated with a respective plurality of said ports to adjust said voltage supplied to each said picture control terminal depending on the selected one of said ports associated therewith and its associated resistor.
Claim 2
Dependent Claim
174 words
A monitor-control method comprising the steps of: detecting horizontal and vertical sync frequencies and polarities of horizontal and vertical sync signals input from a video card; determining, in a microprocessor, a video mode of said video card, using the detected horizontal and vertical sync frequencies and polarities; producing an oscillating voltage in accordance with corresponding horizontal and vertical sync frequencies by pulse width modulation in which said horizontal and vertical sync frequencies are divided into predetermined levels; outputting a high or low signal, simultaneously while outputting said oscillating voltage, by selecting a respective one of a plurality of ports of a picture control terminal of said microprocessor in accordance with the determined video mode, thereby adjusting a voltage of a signal supplied to said picture control terminal, and connecting resistors to said ports in parallel to each said picture control terminal associated with a respective plurality of said ports to adjust said voltage supplied to each said picture control terminal depending on the selected one of said ports associated therewith and its associated resistor.