×

Electrophotographic copying apparatus including transfer hold-down pump

  • US 4,550,999 A
  • Filed: 03/05/1984
  • Issued: 11/05/1985
  • Est. Priority Date: 03/05/1984
  • Status: Expired due to Fees
First Claim
Patent Images

1. In an electrophotographic copying apparatus in which electrically charged toner of one polarity is transferred from an oppositely electrically charged surface of a photoconductive drum to the front side of a blank sheet for transforming said front side of the blank sheet into an intended copy as the back side of the blank sheet engages the surface of a transfer drum positioned adjacent said photoconductive drum, the transfer of toner occurring within a transfer nip defned by said photoconductive drum and said transfer drum, the improvement comprisinga cam rotating in a timed sequence relative to said transfer drum,a vacuum pump located adjacent said transfer drum and actuated by said cam and in communication with the surface of said transfer drum to create a vacuum at said back side of the blank sheet, whereby said paper is held to the surface of said transfer drum by ambient air pressure and said vacuum, overcoming the electrostatic attraction of the blank sheet to said photoconductive drum.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×