Display panel sustain circuit enabling precise control of energy recovery

Claim 1

An energy efficient driver circuit for driving a display panel having panel electrodes and panel capacitance, said driver circuit comprising: inductor means having a first terminal and a second terminal, said second terminal coupled to said panel electrodes; driving voltage source means for providing a driving voltage; voltage supply means for providing a supply voltage of a magnitude which is greater than said driving voltage; first switch means for selectively coupling said driving voltage source means to said first terminal in response to an input signal transition, said input signal transition commencing a first state wherein, during said coupling, a first current flow occurs through said inductor means to charge said panel capacitance, said inductor means causing said panel electrodes to achieve a voltage in excess of said driving voltage, at which point said first current flow reaches zero; second switch means for selectively coupling said voltage supply means to said second terminal and said panel electrodes; and switch control means coupled to said inductor means and responsive to current flow therein, said switch control means operative during at least a portion of said first state to maintain said second switch means in an open condition, and thereafter in response to a signal derived from said inductor means, to cause a closure of said second switch means at a time which enables said second switch means to be fully conductive at about the time said first current flow reaches zero, whereby said voltage supply means, during a succeeding second state, supplies current to both said panel electrodes and flyback current to said inductor means.