Control system for electrophotographic reproduction machines

Claim 2

A control system for operating a component of an electrophotographic reproduction machine comprising corona charging means adapted to receive a sheet of material to be charged, said corona charging means including at least one corona charging wire and a screen partially surrounding said corona charging wire and having a leakage current of a first level prior to receiving the sheet of material to be charged and having a leakage current varying from said first level after receiving the sheet of material, said leakage current passing from said corona charging wire to said screen; and control means for sensing said variation in leakage current and responsive to said variation in leakage current to control the operation of the component whereby the component is operated in timed relation with the receiving of the sheet of material to be charged at said corona charging means.

Claim 3

The control system as recited in claim 1 wherein said control means includes resistance means connected with said screen to receive said leakage current, and switch means connected across said resistance means and actuated in response to the voltage thereacross.

Claim 4

The control system as recited in claim 2 wherein said switch means includes a controlled rectifier having a gate and a cathode connected across said resistance means, said controlled rectifier being maintained nonconductive by the voltage across said resistance means when said leakage current is at said first level and said controlled rectifier being rendered conductive by the voltage across said resistance means in response to said increased leakage current.

Claim 5

The control system as recited in claim 3 wherein said control means includes a relay winding for controlling the operation of the component, said relay winding being connected in series with the anode and cathode of said controlled rectifier.

Claim 6

The control system as recited in claim 1 wherein said control means includes means for sensing said leakage current passing from said screen to a reference potential.

Claim 7

The control system as recited in claim 5 wherein said current sensing means includes resistance means connected between said screen anD the reference potential to receive said leakage current and switch means responsive to the voltage drop across said resistance means.

Claim 8

The control system as recited in claim 6 wherein said leakage current increases above said first level after said corona charging means receives the sheet of material, and said resistance means includes a variable resistor, said switch means includes a controlled rectifier having a gate connected with said screen, a cathode connected with the reference potential and an anode, and relay means and a source of electricity connected in series between said anode and cathode of said controlled rectifier whereby said controlled rectifier is triggered in response to said variation in leakage current to energize said relay means.

Claim 9

A control system for operating a component of an electrophotographic reproduction machine comprising corona charging means adapted to receive a sheet of material to be charged, said corona charging means including first and second corona electrode devices disposed in diametric opposition to receive the sheet of material to be charged and high impedance generator means supplying a high positive potential to said first corona electrode device and a high negative potential to said second corona electrode device, said corona charging means having a leakage current of a first level prior to receiving the sheet of material to be charged and having a leakage current increasing above said first level after the sheet of material is received between said first and second corona electrode devices; and control means for sensing said increase in leakage current and responsive to said increase in leakage current to control the operation of the component whereby the component is operated in timed relation with the receiving of the sheet of material to be cahrged at said corona charging means.

Claim 10

A control system for operating a component of an electrophotographic reproduction machine comprising corona charging means adapted to receive a sheet of material to be charged, said corona charging means including first and second corona electrode devices disposed in diametric opposition to receive the sheet of material to be charged and high impedance generator means supplying a high positive potential to said first corona electrode device and a high negative potential to said second corona electrode device, said corona charging means having a leakage current of a first level prior to receiving the sheet of material to be charged and having a leakage current increasing above said first level after the sheet of material is received between said first and second corona electrode devices; and control means for sensing said increase in leakage current and responsive to said increase in leakage current to control the operation of the component whereby the component is operated in timed relation with the receiving of the sheet of material to be cahrged at said corona charging means.

Claim 11

The control system as recited in claim 8 wherein said first and second corona electrode devices each includes at least one corona charging wire and a screen partially surrounding said corona charging wire, said leakage current passing from said corona charging wire to said screen of one of said first or second corona electrode devices, and said control means includes means for sensing said leakage current passing from said screen to a reference potential.

Claim 12

The control system as recited in claim 9 wherein said current sensing means includes resistance means connected between said screen and the reference potential to receive said leakage current, and switch means responsive to the voltage drop across said resistance means.