(19)
(11) EP 1 594 016 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
02.03.2011 Bulletin 2011/09

(43) Date of publication A2:
09.11.2005 Bulletin 2005/45

(21) Application number: 05252414.7

(22) Date of filing: 18.04.2005
(51) International Patent Classification (IPC): 
G03G 15/16(2006.01)
(84) Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU MC NL PL PT RO SE SI SK TR
Designated Extension States:
AL BA HR LV MK YU

(30) Priority: 06.05.2004 JP 2004137353

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

(72) Inventor:
  • Sakai, Yoshihiro
    Tokyo 143-8555 (JP)

(74) Representative: Lamb, Martin John Carstairs 
Marks & Clerk LLP 90 Long Acre
London WC2E 9RA
London WC2E 9RA (GB)

   


(54) Belt device, image forming apparatus, and method to control belt speed


(57) A first sensor (6, 70) detects a first speed of the belt (10) based on detection of marks on the belt (10) and a first belt speed controlling unit (70) controls a speed of the belt (10) based on the first speed. A second sensor (65, 70') detects a second speed of the belt (10) based on some other method and a second belt speed controlling unit (70') controls a speed of the belt (10) based on the second speed. A scale-mark degradation determining unit (73) that determines whether there is a degradation in the quality of the marks and detects an amount of degradation upon determining that there is a degradation in the quality of the marks. The first belt speed controlling unit (70) is made to control a speed of the belt (10) if the amount of degradation detected by the scale-mark degradation determining unit (73) is less than a predetermined value, and the second belt speed controlling unit (70') is made to control a speed of the belt (10) if the amount of degradation detected by the scale-mark degradation determining unit (73) is not less than the predetermined value.







Search report