IMAGE FORMING APPARATUS AND PROCESS CARTRIDGE INCLUDING A DEVELOPING DEVICE PROVIDED AT LEAST WITH A DEVELOPER HOLDING MEMBER FOR HOLDING A DEVELOPER CONTAINING A TONER AND A DEVELOPER REGULATING MEMBER

摘要

An image forming apparatus includes an electrophotographic photosensitive member rotated at a peripheral speed of 150 mm/second or more and a specific toner. The toner has a weight-average particle diameter from 5 to 12 mum, and of the toner having a circle-equivalent diameter of 3 mum or more, particles with a circularity of 0.900 or more are present at a rate of 90% or more in a number-based cumulative valve. The toner also satisfies one of two sets of conditions defined by the relationship between a cut rate and a weight-average particle diameter and the relationship between a number-based cumulative valve and a weight-average particle diameter. The cut rate Z is represented by the expression:wherein A is a concentration of all the measured particles and B is a concentration of the measured particles whose circle-equivalent diameters are 3 mum or more.