Scanning apparatus for electroluminescent crossed-grid panel

Claim 1

A scanning apparatus for an electroluminescent crossed-grid panel having a multiplicity of electroluminescent elements at the intersections of horizontal and vertical electrodes, said scanning apparatus comprising a horizontal electrode driving circuit adapted to be coupled to said horizontal electrodes and having a set of pulse generators for supplying a selecting pulse to a horizontal electrode to be scanned sequentially in response to a synchronizing signal of a video signal and for supplying the remaining horizontal electrodes at the same time with blanking pulses which are in phase with said selecting pulse and have an amplitude less than one-half of said selecting pulse, said horizontal electrode driving circuit further including a set of resonant circuits, each of which includes an inductor in series and a capacitor in parallel with a corresponding horizontal electrode and pulse generator, each said resonant circuit having a natural frequency determined by said pulse generator, said inductor, and said capacitor, one-half of the reciprocal of said natural frequency being less than the width of said selecting pulse and being more than three times as large as the rise time of said selecting pulse; a video signal supply means coupled to said horizontal electrode driving circuit for supplying the synchronizing signal of the video signal; a vertical electrode driving circuit consisting essentially of a set of brightness control circuits, each of which includes a transistor having the collector thereof adapted to be connected to a corresponding vertical electrode, and a circuit for supplying a multi-channel video signal connected to the base of each said transistor, and a delay means having a delay time corresponding to one horizontal period of the video signal and having taps connected to associated brightness control circuits, respectively; a sample reset signal generator coupled to said brightness control circuits and to said video signal supply means for supplying a sample signal and a reset signal to said brightness control circuits in response to synchronizing signals of a video signal; said video signal supply means being coupled to said vertical electrode driving circuit for supplying an amplified video signal to the input terminal of said delay means; whereby each of said electroluminescent elements along the horizontal electrode to be scanned is simultaneously controlled with respect to the brightness thereof by varying the collector resistance of each of said transistors in response to the multi-channel video signals which are sampled at each tap of said delay means at the same time.