Electrostatic recorder with resilient conductive fabric backup electrode

Claim 1

In an electrostatic recorder responsive to input signals for forming a surface charge image on a recording medium having a charge retentive coating and a conductive base, the combination comprising: recording head means having a plurality of styli electrodes; a conductive resilient fabric base backup electrode with extending looped piles mounted directly adjacent to the plurality of styli electrodes, the looped piles having a relatively low coefficient of friction and good recovery characteristics to permit easy passage of the recording medium while the recording medium is engaged between the recording head means and the looped piles of the backup electrode; rigid means for mounting the backup electrode; means for urging the rigid means and the recording head means together with the recording medium engaged therebetween with the backup electrode conductive looped piles in electrical contact with the conductive base to establish a charging path from the plurality of styli electrodes through the recording medium to the backup electrode, the charging path traversing the recording medium substantially perpendicularly for including a minimum of the recording medium in the charging path; means for moving the recording medium past the recording head while the recording medium is electrically engaged between the plurality of styli electrodes and the backup electrode; means for receiving and processing the input signals for addressing and activating selected styli to cause charging current to flow through the charging path which in conjunction with the moving recording medium creates a surface charge image on the charge retentive coating of the recording medium.