Duty cycle alteration circuit

A duty cycle alteration circuit in a monitor, comprising:

• a microcomputer for outputting a waveform amplifying ratio control signal;
• a direct current level adjusting circuit for inputting said waveform amplifying ratio control signal according to a horizontal size adjusting signal supplied from said microcomputer and for converting said waveform amplifying ratio control signal into a direct current signal;
• an integrating circuit for inputting a flyback pulse generated within said monitor, said integrating circuit being charged and discharged in accordance with the supplied flyback pulse for generating a triangular wave;
• an amplifying circuit for amplifying said triangular wave, generated by said integrating circuit, in response to the direct current signal, output from said direct current level adjusting circuit, for outputting an amplified triangular wave;
• and
• a Schmitt circuit for establishing a logic “high” level and a logic “low” level centering around a reference level according to the amplified triangular wave supplied from said amplifying circuit and for changing a duty cycle on the basis of the logic “high” and “low” levels and for outputting a rectangular wave having an altered duty cycle.

A horizontal duty cycle alteration circuit alteration circuit in a monitor, comprising:

• a microcomputer for inputting a horizontal synchronous signal and a vertical synchronous signal to discriminate a video mode and for outputting a waveform amplifying ratio control signal according to a horizontal size adjusting signal, based upon the discriminated video signal;
• a duty cycle alteration circuit for inputting and amplifying said waveform amplifying ratio control signal according to the horizontal size adjusting signal outputted form said microcomputer and for outputting a rectangular wave having an altered duty cycle;
• a horizontal size drive circuit for inputting the rectangular wave outputted from said duty cycle alteration circuit and for fully amplifying the inputted rectangular wave;
• a regulation sensor for sensing a variation of a sawtooth current outputted from a horizontal output circuit and for outputting a sensed variation signal corresponding to the sensed variation of said sawtooth current;
• a horizontal regulation controller for inputting the sensed variation signal of said sawtooth current outputted from said regulation sensor and for inputting a horizontal drive signal outputted from a horizontal size drive circuit and for stabilizing an output waveform of said sawtooth current;
• and
• a horizontal regulation output circuit for inputting a horizontal size adjusting signal outputted from said horizontal regulation controller and for controlling an output of said horizontal output circuit.

A duty cycle alteration circuit in a video display monitor, comprising:

• a microcomputer generating a pulse width modulation adjusting level signal;
• an amplifying circuit amplifying said pulse width modulation adjusting level signal generated by said microcomputer and outputting an amplified triangular wave;
• and
• a Schmitt circuit establishing a logic “high” level and a logic “low” level centering around a reference level according to the amplified triangular wave output from said amplifying circuit to change a duty cycle on the basis of the logic “high” and “low” levels for outputting a rectangular wave having an altered duty cycle.