Bi-directional television scan system

Claim 1

In a television system, bidirectional horizontal scan circuitry comprising: a master sync signal generator; a vertical sync signal generator responsive to master sync signals to provide vertical sync signals; a horizontal sync signal generator responsive to master sync signals to provide horizontal sync signals; triangular waveform generator means responsive to the output of said horizontal sync signal generator and providing a symmetrical triangular waveform output for application to horizontal deflection means; stairstep waveform generator means responsive to the outputs of said vertical and horizontal sync signal generators and providing a stairstep vertical deflection signal for application to vertical deflection means comprising: a first capacitor; a flip-flop responsive to said vertical sync signal to alternately provide first and second outputs each of voltage V1; first diode means connecting said first output to charge said first capacitor; voltage divider means connected to receive said second output and operative to provide a reduced voltage of V1- e/2; second diode means connecting said reduced output to charge said first capacitor; a second capacitor; normally non-conductive transistor means connected between said capacitors; and second means responsive to said horizontal sync signals to provide a square wave of a predetermined voltage e to said second capacitor, whereby said transistor is periOdically rendered conductive and said charge on said first capacitor is reduced with each conductive period by the voltage increment e; whereby scansion is characterized by horizontal, parallel sweeps in alternate directions, with a vertical step at the end of each sweep.