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Electrophotographic negative charged developer having specific voltage dependant index

IP.com Disclosure Number: IPCOM000033707D
Publication Date: 2004-Dec-23
Document File: 1 page(s) / 35K

Publishing Venue

The IP.com Prior Art Database

Abstract

This Invention describes emulsion aggregation negatively charged electrophotographic developers.

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Electrophotographic negative charged developer having specific voltage dependant index

This Invention describes emulsion aggregation negatively charged electrophotographic developers.

A negatively charged electrophotographic developer comprising a magnetic carrier and a toner has a voltage-dependent index, Y, of the developer, obtained from resistance values R500 (Wcm) and R2500 (Wcm), which are measured at electric field strengths of 500 V/cm and 2500 V/cm, respectively, in accordance with the formula:
          Y =  log (R500      (1)
                  log (R2500)
This developer also has a number proportion X (%), in the total toner, of a non-charged toner which is within a region of the formula:
               Q/D > - 0.2          (2)
in a charged amount distribution of toner defined by a charged amount Q (fC) and a particle size D(mm) of the toner, have a relation satisfying the following formula:
          Y >    3X      + 1     (3)
                    400

This electrophotographic developer may also have its voltage-dependent index, Y, within a range of 1.00 to 1.50.

The electrophotographic developer may in addition have the number proportion X (%) of the non-charged toner to the total toner be not more than 40%.

Eight negatively charged emulsion aggregation developers used in an electrophotographic copier are used for this example. These developers were sampled across th...