Electro-optical processor having electrical signal writing means

Claim 1

Apparatus for writing time varying signal information on a non-conductive recording medium in the form of a spatially modulated electrostatic charge pattern comprising, means for supporting the recording medium in proximate movable relation to precharging electrode means and writing electrode means, said precharging electrode means including a precharging electrode disposed adjacent a side of the recording medium and operative in conjunction with conductive means disposed on the opposite side of the recording medium, said writing electRode means including a writing electrode disposed adjacent a side of the recording medium and also operative in conjunction with conductive means disposed on the opposite side of the recording medium, means for energizing the precharging electrode to establish on a given region of the recording medium moving past the precharging electrode a uniform electrostatic charge distribution of a predetermined polarity at a level capable of producing a discharge across the gap between the writing electrode and the recording medium when the uniformly precharged region thereof moves past the writing electrode held in a de-energized condition, and means for applying to the writing electrode time-amplitude varying signal information of the same polarity and lower amplitude than said uniform electrostatic charge so that when the instantaneous value of the time varying signal is suitably lower than the uniform charge an electrical discharge is produced across the gap between the writing electrode and the adjacent segment of the recording medium causing the charge on said segment to change to a value substantially equal to the potential on the writing electrode thereby spatially modulating said uniform charge by partial erasure thereof to produce on said recording medium as it moves past the writing electrode an electrostatic charge pattern representative of said time varying signal information.