Abstract: The present invention relates to a rotary lawn mower blade that is designed to make multiple cuts of grass or other material being cut as the lawn mower blade is advanced over a cutting area. This is achieved by providing a generally upturned cutting edge about each end of the lawn mower blade. Because the cutting edge is inclined outwardly and upwardly, it follows that the grass or other material being cut will be progressively cut and recut as the mower blade passes over underlying material to be cut.

Abstract: Large values of avalanche current are avoided in a gas discharge display panel by "staggering" in time the application of the sustain voltage waveforms to different portions of the display panel. A plurality of individual sustain circuit modules each having two 100 v FET's are connected to a common sustain circuit module having another two 100 v FET's. The "staggered" sustain operation is provided by selectively controlling the individual sustain circuit modules. The individual and common sustain circuit modules combine to alternatively produce 0-200 v square wave or a 0-100-200 v return-to-midpoint waveform by selectively controlling the FET's.

Abstract: A plasma discharge display device is operated at a high frequency above the response range of the inherent wall charge storage phenomenon and utilizes a refresh buffer. The vertical drive selection includes a pair of shift registers operated in parallel into which data from the host or associated controller is loaded, with an individual driver associated with each register stage. The horizontal lines are addressed through associated shift registers in an even-odd interlace sequence to generate a display on a horizontal scan basis. The horizontal drivers are referenced at the level and frequency of the high frequency energizing signals, while the vertical drivers are selectively set to ground or a positive a.c. voltage according to the state of associated register cells. By using the high frequency signal in the horizontal axis as a floating reference and unique selection techniques, the display is operated by low voltage signals.

Abstract: An improved write waveform is provided for a gas panel of the type in which light emitting cells are formed in an ionizable medium at the cross points of a set of horizontally and vertically extending insulated wires. A write pulse of high amplitude is followed by an opposite polarity pulse of an amplitude and width to produce cell wall charge storage from the ionization that accompanies the fall of the high amplitude write pulse. The invention also provides a method and circuit for reading the state of a cell by applying the high amplitude write pulse to a cell and detecting the difference between the smaller current that occurs at the leading edge of the write pulse for a previously written cell and the larger current for an erased cell.