Bias cleaning system and electrostatic printing apparatus therewith and operating method thereof

A method of operating a bias cleaning system having an electrically conductive brush roller for collecting charge-carrying toner carried on a rotating toner carrying nonphotosensitive member and a collecting roller for collecting toner from said electrically conductive brush roller, comprising the steps of:

• scrubbing the rotating toner carrying member using said brush roller under a condition in which a direct current voltage of opposite polarity to the charge on the toner is applied to the electrically conductive brush roller;
• contacting the electrically conductive brush roller with said collecting roller under a condition in which a direct current voltage having the same polarity as and a higher level than the voltage applied to the electrically conductive brush roller is applied to the collecting roller;
• stopping rotation of the toner carrying member;
• and then
• moving said brush roller and said collecting roller in a direction which is opposite to a moving direction of said brush roller and said collecting roller before stopping rotation of the toner carrying member.

A method of operating a bias cleaning system having an electrically conductive brush roller for collecting remaining charge-carrying toner on a rotatable toner carrying member and a collecting roller for collecting toner from said electrically conductive brush roller, comprising the steps of:

• starting rotation of said toner carrying member;
• scrubbing the toner carrying member using said brush roller under a condition in which a direct current voltage of opposite polarity to the charge on the toner is applied to the electrically conductive brush roller;
• and
• contacting the electrically conductive brush roller with said collecting roller under a condition in which a direct current voltage having the same polarity as and a higher level than the voltage applied to the electrically conductive brush roller is applied to the collecting roller;
• wherein
• said direct current voltage is applied to the electrically conductive brush roller after starting rotation of the toner carrying member, and rotation of the toner carrying member is stopped after turning off the direct current voltage applied to the electrically conductive brush roller.

A method of operating a bias cleaning system having an electrically conductive brush roller for collecting remaining charge-carrying toner on a rotatable toner carrying nonphotosensitive member and a collecting roller for collecting roller toner from said electrically conductive brush roller, comprising the steps of:

• starting rotation of said toner carrying member;
• scrubbing the toner carrying member using said brush roller under a condition in which a direct current voltage of opposite polarity to the charge on the toner is applied to the electrically conductive brush roller;
• and
• contacting the electrically conductive brush roller with said collecting roller under a condition in which a direct current voltage having the same polarity as and a higher level than the voltage applied to the electrically conductive brush roller is applied to the collecting roller;
• wherein
• a direct current voltage is applied to said collecting roller not before a direct current voltage is applied to said electrically conductive brush roller.

A method of operation a bias cleaning system in an electrostatic printing apparatus, in which sheets are supplied to a printing region for printing, having an electrically conductive brush roller for collecting remaining toner charge-carrying on a rotatable toner carrying member and a collecting roller for collecting toner from said electrically conductive brush roller, comprising the steps of:

• starting rotation of said toner carrying member;
• supplying sheets to said printing region for printing;
• scrubbing the toner carrying member under a condition in which a direct current voltage of opposite polarity to the charge on the toner is applied to the electrically conductive brush roller;
• contacting the electrically conductive brush roller with said collecting roller under a condition in which a direct current voltage having the same polarity as and a higher level than the voltage applied to the electrically conductive brush roller is applied to the collecting roller;
• and
• counting the number of sheets supplied to said printing region;
• wherein
• the voltages applied to the electrically conductive brush roller and the collecting roller are increased in a step by step manner corresponding to an increase in the counted number of sheets.

A bias cleaning system comprising:

• an electrically conductive brush roller for collecting a charge-carrying toner which has adhered on a rotatable toner carrying member by scrubbing the toner from the toner carrying member under a condition in which said toner carrying member is rotating in contact with said brush roller and a direct current voltage of opposite polarity to the charge on the toner is applied to said brush roller;
• a collecting roller for collecting the toner scrubbed off said toner carrying member by said brush roller by effecting contact between the collecting roller and the electrically conductive brush roller under a condition in which a direct current voltage having the same polarity as and a higher level than the voltage applied to the electrically conductive brush roller;
• and
• an opposed roller placed in opposition to the electrically conductive brush roller with the toner carrying member being interposed therebetween, wherein a high resistivity coating film is formed on at least a part of the opposed roller which is not in contact with the toner carrying member so as to contact directly the electrically conductive brush roller.

A method of operation a bias cleaning system in an electrostatic printing apparatus, in which sheets are supplied to a printing region for printing, having an electrically conductive brush roller for collecting remaining toner charge-carrying nonphotosensitive on a rotatable toner carrying member, a collecting roller for collecting toner from said electrically conductive brush roller and an opposed roller place in opposition to the brush roller with the toner carrying member being interposed therebetween, comprising the steps of:

• starting rotation of said toner carrying member;
• supplying sheets to said printing region for printing;
• scrubbing the toner carrying member under a condition in which a direct current voltage of opposite polarity to the charge on the toner is applied to the electrically conductive brush roller;
• contacting the electrically conductive brush roller with said collecting roller under a condition in which a direct current voltage having the same polarity as and a higher level than the voltage applied to the electrically conductive brush roller;
• wherein
• the voltage applied to the opposed roller is decreased in a step by step manner corresponding to an increase in a counted number of sheets.

An electro-static printing apparatus using a belt transfer system for transferring a charged toner image on a photosensitive body to a print paper sheet by causing the print paper sheet mounted on a rotating transfer belt formed of a dielectric material come into contact with the photosensitive body while applying a charge of opposite polarity to that of the toner to the reverse side surface of the transfer belt, which apparatus comprises:

• an electrically conductive brush roller for collecting remaining toner which has adhered on said transfer belt by scrubbing the toner adhering to said transfer belt under a condition in which a direct current voltage of the opposite polarity to that of the charge on the toner is applied to said electrically conductive brush roller;
• a collecting roller for collecting from said brush roller toner by contacting the electrically conductive brush roller under a condition in which a direct current voltage having the same polarity as and a higher voltage level than the voltage applied to the electrically conductive brush roller is applied to said collecting roller;
• and
• toner charge decreasing means for decreasing the amount of charge on the toner in a region of the transfer belt up-stream of the electrically conductive brush roller in the moving direction of the transfer belt.

An electro-static printing apparatus of intermediate transfer body type in which contact is effected between an intermediate transfer body made of a dielectric material and a photosensitive body having a charged toner image formed thereon, the charged toner image on the photosensitive body is transferred to the intermediate transfer body, and the toner image on the intermediate transfer body is transferred to a print paper sheet, which apparatus comprises:

• an electrically conductive brush roller for collecting remaining toner which has adhered on the intermediate transfer body by scrubbing the intermediate transfer body under a condition in which a direct current voltage of opposite polarity to that of the charge on the toner is applied to said electrically conductive brush roller;
• a collecting roller for collecting toner from said brush roller by of contacting the electrically conductive brush roller under a condition in which a direct current voltage having the same polarity as and a higher voltage level than the voltage applied to the electrically conductive brush roller is applied to the collecting roller;
• and
• toner charge decreasing means for decreasing the amount of charge on the toner in the region of the intermediate transfer body up-stream of the electrically conductive brush roller in the moving direction of the intermediate transfer body.

A bias cleaning system comprising:

• an electrically conductive brush roller for collecting a charge-carrying toner which has adhered on a rotatable toner carrying nonphotosensitive member by scrubbing the toner from the toner carrying member under a condition in which said toner carrying member is rotating in contact with said brush roller and a direct current voltage of opposite polarity to the charge on the toner is applied to said brush roller;
• a collecting roller for collecting the toner scrubbed off said toner carrying member by said brush roller by effecting contact between the collecting roller and the electrically conductive brush roller under a condition in which a direct current voltage having the same polarity as and a higher level than the voltage applied to the electrically conductive brush roller is applied to the collecting roller;
• and
• control means for moving said brush roller and said collecting roller in a reverse direction opposite to the moving direction thereof during scrubbing of the toner carrying member before stopping of the toner carrying member.

A bias cleaning system comprising:

• an electrically conductive brush roller for collecting a charge-carrying toner which has adhered on a rotatable toner carrying nonphotosensitive member by scrubbing the toner from the toner carrying member under a condition in which said toner carrying member is rotating in contact with said brush roller and a direct current voltage of opposite polarity to the charge on the toner is applied to said brush roller;
• a collecting roller for collecting the toner scrubbed off said toner carrying member by said brush roller by effecting contact between the collecting roller and the electrically conductive brush roller under a condition in which a direct current voltage having the same polarity as and a higher level than the voltage applied to the electrically conductive brush roller is applied to the collecting roller;
• and
• control means for applying said direct current voltage to said electrically conductive brush roller after starting rotation of the toner carrying member and for stopping rotation of the toner carrying member after turning off the direct current voltage applied to the electrically conductive brush roller.

A bias cleaning system comprising:

• an electrically conductive brush roller for collecting a charge-carrying toner which has adhered on a rotatable toner carrying member by scrubbing the toner from the toner carrying member under a condition in which said toner carrying member is rotating in contact with said brush roller and a direct current voltage of opposite polarity to the charge on the toner is applied to said brush roller;
• a collecting roller for collecting the toner scrubbed off said toner carrying member by said brush roller by effecting contact between the collecting roller and the electrically conductive brush roller under a condition in which a direct current voltage having the same polarity as and a higher level than the voltage applied to the electrically conductive brush roller is applied to the collecting roller;
• and
• control means for applying said direct current voltage to said collecting roller not before a direct current voltage is applied to said electrically conductive brush roller.

A bias cleaning system comprising:

• an electrically conductive brush roller for collecting a charge-carrying toner which has adhered on a rotatable toner carrying nonphotosensitive member by scrubbing the toner from the toner carrying member under a condition in which said toner carrying member is rotating in contact with said brush roller and a direct current voltage of opposite polarity to the charge on the toner is applied to said brush roller;
• a collecting roller for collecting the toner scrubbed off said toner carrying member by said brush roller by effecting contact between the collecting roller and the electrically conductive brush roller under a condition in which a direct current voltage having the same polarity as and a higher level than the voltage applied to the electrically conductive brush roller is applied to the collecting roller;
• means for supplying sheets to a printing zone for printing;
• and
• control means for increasing the voltages applied to the electrically conductive brush roller and the collecting roller in a step by step manner corresponding to an increase in a number of sheets supplied to said printing zone.

A bias cleaning system comprising:

• an electrically conductive brush roller for collecting a charge-carrying toner which has adhered on a rotatable toner carrying nonphotosensitive member by scrubbing the toner from the toner carrying member under a condition in which said toner carrying member is rotating in contact with said brush roller and a direct current voltage of opposite polarity to the charge on the toner is applied to said brush roller;
• a collecting roller for collecting the toner scrubbed off said toner carrying member by said brush roller by effecting contact between the collecting roller and the electrically conductive brush roller under a condition in which a direct current voltage having the same polarity as and a higher level than the voltage applied to the electrically conductive brush roller is applied to the collecting roller;
• an opposed roller placed in opposition to the electrically conductive brush roller with the toner carrying member being interposed therebetween, said opposed roller having a direct current voltage applied thereto;
• means for supplying sheets to a printing zone for printing;
• and
• control means for decreasing the voltage applied to the opposed roller in a step by step manner corresponding to an increase in a number of sheets supplied said printing zone.

A bias cleaning system comprising:

• an electrically conductive brush roller for collecting a charge-carrying toner which has adhered on a rotatable toner carrying nonphotosensitive member by scrubbing the toner from the toner carrying member under a condition in which said toner carrying member is rotating in contact with said brush roller and a direct current voltage of opposite polarity to the charge on the toner is applied to said brush roller;
• a collecting roller for collecting the toner scrubbed off said toner carrying member by said brush roller by effecting contact between the collecting roller and the electrically conductive brush roller under a condition in which a direct current voltage having the same polarity as and a higher level than the voltage applied to the electrically conductive brush roller is applied to the collecting roller;
• toner charge decreasing means for decreasing the amount of charge on the toner on the toner carrying member in a region up-stream of the electrically conductive brush roller in the moving direction of the toner carrying member;
• and
• a flicker bar acting on brush fibers in the electrically conductive brush roller to remove toner therefrom.

An electrically conductive brush roller for use in a bias cleaning system, said bias cleaning system comprising:

• an electrically conductive brush roller for collecting a charge-carrying toner which has adhered on a rotatable toner carrying a non-photosensitive member by scrubbing the toner from the toner carrying non-photosensitive member under a condition in which said toner carrying non-photosensitive member is rotating in contact with said brush roller and a direct current voltage of opposite polarity to the charge on the toner is applied to said brush roller;
• a collecting roller for collecting the toner scrubbed off said toner carrying non-photosensitive member by said brush roller by effecting contact between the collecting roller and the electrically conductive brush roller under a condition in which a direct current voltage having the same polarity as and a higher level than the voltage applied to the electrically conductive brush roller is applied to the collecting roller;
• and
• toner charge decreasing means for decreasing the amount of charge on the toner carried on the toner carrying non-photosensitive member in a region up-stream of the electrically conductive brush roller in the moving direction of the toner carrying non-photosensitive member;
• wherein said electrically conductive brush roller includes a resistivity per unit area in the range between 10.sup.-2 M .OMEGA./cm.sup.2 and 4 M .OMEGA./cm.sup.2 and a high cleaning efficiency when the amount of charge on the toner carried on the toner carrying non-photosensitive member is reduced to 15 .mu.C/g or less.