Device for recording images with signal level being maintained for one line period

Abstract

A method of recording an electrostatic charge pattern on an insulating layer. The method comprises the steps of scanning a pattern line-wise to produce an electric signal which is composed of a multiplicity of distinct electric signals determined by successively scanned portions of the pattern. The distinct electrical signals are applied to different places of the insulating layer during a period which is greater than the corresponding period during which the corresponding area of the pattern is being scanned. The charge pattern on the insulating layer is developed in a known way to produce a visible image.

We claim: 
     
       1. A device for recording a two-dimensional image pattern which comprises: a. means for producing .[.an electric image signal.]. .Iadd.a collection of electrical signals in sequence .Iaddend.which is representative of an image pattern to be recorded, .[.said electric image signal being composed of.]. .Iadd.from which .Iaddend.a plurality of line electrical signals in sequence .[.may be.]. .Iadd.are derived .Iaddend.and each such line signal being composed of a plurality of elementary image electrical signals in sequence,   b. recording member composed of a plurality of separate signal-tracing electrodes arranged in spaced relation to each other in one direction,   c. means for .Iadd.stepwise .Iaddend.transporting a recording material capable of being electrostatically charged along said electrodes .Iadd.said transporting means comprising a step motor adapted to rotate through a discrete arc of predetermined extent during each step and to thereby advance said recording material a discrete linear distance proportionate to said arc extent, .Iaddend.in a direction normal to the direction of spacing of said electrodes,   d. plural amplifier circuit means each having the output thereof connected to a corresponding signal-tracing electrode and operative on receiving an elementary image signal at their input to raise the potential of such electrode to a value sufficient to deposit an electrostatic charge on the recording material,   e. plural electric storage circuit means associated with said amplifier circuit means for maintaining the input of each associated amplifier means at an electric potential corresponding with that of a particular elementary image signal for a period of time which is at least equal to the period of one line signal, .Iadd.whereby each operative electrode retains an electrostatic charge for a period of time at least equal to the period of one line signal, .Iaddend.   f. plural gate circuit means connecting the elementary image signals of one line signal one by one in sequence to said associated amplifier and electric storage circuit means,   g. means for closing said gate circuit means in timed relation with the sequence of the elementary image signals of one line signal,   h. means for removing the stored electric signals from the storage circuit means and the potential from said electrodes prior to the recording of an elementary image signal which belongs to another line signal,   i. .Iadd.synchronizing .Iaddend.means responsive to the sequence of the line signals to control the .Iadd.stepwise .Iaddend.transportation of the recording material at a rate proportional with the succession of the line signals of the image signal, .Iadd.said synchronizing means activating said step motor to advance said recording material to effect deposition of said charges of each line signal thereon while the material is moving said discrete linear distance, .Iaddend.and   j. means for developing the electrostatic image thus formed on the recording material.   
     
     
       2. A device according to claim 1 wherein each electric storage circuit means is controlled to store an elementary image signal during a lapse of time which is comprised between a line period and .[.half an image period..]. .Iadd.the period of one of one of said collections of electrical signals in sequence. .Iaddend. 
     
     
       3. Device according to claim 1, including an amplification electrode which runs closely parallel to the recording member at its upstream side relative to the direction of movement of the recording material is connected to a potential of a polarity opposite to that of said signal-tracing electrodes. 
     
     
       4. Device according to claim 1, wherein said means for closing said gate circuit means in timed relation comprises a shift register. 
     
     
       5. Device according to claim 1, wherein said signal-tracing electrodes are in the form of needle-like conductors, the extremities of which facing the recording material are arranged in a line. 
     
     
       6. Device according to claim 1, wherein the said signal-tracing electrodes mechanically contact the recording material. 
     
     
       7. Device according to claim 1, including a backing electrode which runs parallel to the recording member at the rear side of the recording material and is connected to a potential of a polarity opposite to that of said signal-tracing electrodes.