Patent ID: 6150999
Filing Date: 2000-11-21
Classification: G09G

Abstract:
A driving circuit for driving a plasma display unit over which the plasma display unit can be repeatedly charged for sustaining a display of an image signal, the plasma display unit comprising a first end and a second end, the driving circuit comprising a first driving circuit, a second driving circuit, a control circuit, and a power supply, the first driving circuit comprising a first inductor, a first switch electrically connected between the power supply and a first end of the first inductor, a second switch electrically connected between the first end of the first inductor and a ground, a first diode electrically connected between the power supply and a second end of the first inductor, a second diode electrically connected between the second end of the first inductor and the ground, wherein the first end of the plasma display unit is electrically connected with the second end of the first inductor, the second driving circuit comprising a third switch electrically connected between the power supply and the second end of the plasma display unit, a fourth switch electrically connected between the second end of the plasma display unit and the ground, the control circuit being used for controlling the first, second, third and fourth switches so that the power supply can repeatedly charge the plasma display unit through the first and second driving circuits, each of the first and second switches comprising a transistor with a parasitic diode existed between a drain and source of the transistor; wherein the control circuit will:step (1) switch on the first switch and fourth switch to increase the current flowing through the first inductor and the potential at the first end of the plasma display unit, and when the potential at the first end of the plasma display unit rises to the potential of the power supply, the first diode will be turned on and then the current of the first inductor will flow through the first diode and first switch to form a first circulating current;step (2) switch off the first switch and fourth switch, the parasitic diode of the second switch will be forced to be turned on because the current of the first inductor must follow a continuity character of current, and then the first circulating current will flow through the power supply and the parasitic diode of the second switch into the first inductor;step (3) switch on the second switch and third switch, the second switch is turned on at a zero crossing voltage because the parasitic diode of the second switch is in an on state, the first diode will be turned off when the current of the first inductor drops to 0A, the plasma display unit will start charging the first inductor through the first inductor and second switch to increase the current of the first inductor in a reverse direction, the potential at the first end of the plasma display unit will drop, the second diode will be turned on when the potential at the first end of the plasma display unit drops to a ground potential, and the current of the first inductor flowing in the reverse direction will flow through the second switch and second diode to form a second circulating current;step (4) switch off the second switch and third switch, the parasitic diode of the first switch will be forced to be turned on because the current of the first inductor must follow the continuity character, and then the second circulating current will flow through the parasitic diode of the first switch back to the power supply;step (5) switch on the first switch and fourth switch, the first switch is turned on at a zero crossing voltage because the parasitic diode of the first switch is in an on state, the second diode will be switched off when the current of the first inductor flowing in the reverse direction drops to 0A, the power supply will then charge the plasma display unit through the first switch and first inductor, the current of the first inductor will increase and the potential at the first end of the plasma display unit will rise, the first diode will be turned on when the potential at the first end of the plasma display unit rises to the potential of the power supply, and the current of the first inductor will flow through the first diode and first switch to form a first circulating current;step (6) repeat steps (2) to (5) so that the plasma display unit can be repeatedly charged for sustaining the display of the image signal.