Reducing toning spacing sensitivity
View Patent ↗A method for reducing toning spacing sensitivity in an electrophotographic process is disclosed. The method includes providing a rotating magnetic member within a conductive non-magnetic development sleeve; providing a developer to the non-magnetic development sleeve for use with the rotating magnetic member including: i) hard magnetic particles with a coercivity of greater than 300 oersted and an induced moment of less than 20 emu per gram at an applied field of 1000 oersted; and ii) soft magnetic particles with a coercivity of less than 300 oersted and an induced moment of greater than 20 emu per gram an applied field of 1000 oersted; and iii) toner particles. The method further includes moving a charged receiving medium into a toner transfer relationship with the developer on the non-magnetic development sleeve so as to provide a developed image on the receiving medium with reduced toning spacing sensitivity.
1. A method for reducing toning spacing sensitivity in an electrophotographic process comprising:
(a) providing a rotating magnetic member within a conductive non-magnetic development sleeve;
(b) providing a developer to the non-magnetic development sleeve for use with the rotating magnetic member including:
(i) hard magnetic particles with a coercivity of greater than 300 oersted and an induced moment of less than 20 emu per gram at an applied field of 1000 oersted;
(ii) soft magnetic particles with a coercivity of less than 300 oersted and an induced moment of greater than 20 emu per gram an applied field of 1000 oersted; and
(iii) toner particles;
c) treating the hard magnetic particles in a magnetic field to lower the induced moment to less than 20 emu per gram at an applied field of 1000 oersted before providing the developer to the non-magnetic development sleeve; and
(d) moving a charged receiving medium into a toner transfer relationship with the developer on the non-magnetic development sleeve so as to provide a developed image on the receiving medium with reduced toning spacing sensitivity.
2. The method of claim 1 wherein the non-magnetic sleeve is rotated.
3. The method of claim 1 wherein the non-magnetic sleeve is stationary.
4. The method of claim 1 wherein the toner concentration of the developer is in a range from 3% to 25% by weight.
5. The method of claim 1 wherein the percentage of soft magnetic particles in the carrier component of the developer is in a range from 10% to 75% by weight.
6. The method of claim 1 wherein the hard magnetic particles comprise strontium ferrite.
7. The method of claim 1 wherein the hard magnetic particles are composite particles with hard magnetic materials dispersed in a resin matrix.
8. The method of claim 1 wherein the soft magnetic particles comprise manganese ferrite, lithium ferrite, copper-zinc ferrite or manganese-magnesium-strontium ferrite.
9. The method of claim 1 wherein the soft magnetic particles are composite particles with soft magnetic materials dispersed in a resin matrix.