(19)
(11)EP 2 708 957 A3

(12)EUROPEAN PATENT APPLICATION

(88)Date of publication A3:
06.12.2017 Bulletin 2017/49

(43)Date of publication A2:
19.03.2014 Bulletin 2014/12

(21)Application number: 13183922.7

(22)Date of filing:  11.09.2013
(51)International Patent Classification (IPC): 
G03G 15/16(2006.01)
(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
Designated Extension States:
BA ME

(30)Priority: 18.09.2012 JP 2012205116
13.05.2013 JP 2013101677

(71)Applicant: Ricoh Company, Ltd.
Tokyo 143-8555 (JP)

(72)Inventors:
  • Tanaka, Shinya
    Ohta-ku Tokyo 143-8555 (JP)
  • Ishii, Hirokazu
    Tokyo 143-8555 (JP)
  • Shimizu, Yasunobu
    Tokyo 143-8555 (JP)
  • Nakamura, Keigo
    Tokyo 143-8555 (JP)

(74)Representative: Schwabe - Sandmair - Marx 
Patentanwälte Rechtsanwalt Partnerschaft mbB Joseph-Wild-Straße 20
81829 München
81829 München (DE)

  


(54)Image forming apparatus


(57) An image forming apparatus includes a power source (39) to output a voltage having an alternating waveform to transfer a toner image from an image bearing member (31) to a recording medium. A time-averaged value (Vave) of the voltage has a polarity in a transfer direction, in which the toner image is transferred from the image bearing member (31) to the recording medium, and an absolute value of the time-averaged value is greater than a midpoint value (Voff) of the voltage intermediate between a maximum value and a minimum value of the voltage. As a roughness of the recording medium increases, a duty ratio (Duty) expressed by A / (A+B) is reduced, where A is an area of the waveform of the voltage in a return direction opposite the transfer direction relative to the midpoint value in one cycle and B is an area in the transfer direction relative to the midpoint value.







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