Patent ID: 8000639

Claim:
A developing device using developer containing a toner and a carrier to makes an electrostatic latent image on an electrostatic latent image bearing body into a visible image, comprising: developer containing a toner and a carrier, the toner being charged to a first polarity by frictional contact between the toner and the carrier, while the carrier being charged to a second polarity which is different from the first polarity; a first conveyance member which is rotationally driven; a second conveyance member which faces the first conveyance member via a first region, which is rotationally driven so as to move to a direction opposed to the first conveyance member in the first region, and which faces the electrostatic latent image bearing body via a second region; first electric field unit which forms a first electric field between the first conveyance member and the second conveyance member to move the toner in the developer retained by the first conveyance member to the second conveyance member; and second electric field forming unit which forms a second electric field between the second conveyance member and the electrostatic latent image bearing body to move the toner retained by the second conveyance member to an electrostatic latent image on the electrostatic latent image bearing body for making the electrostatic latent image into a visible image, wherein the first electric field is an oscillating electric field having both a function to supply the toner to the second conveyance member and a function to collect the toner from the second conveyance member while a time average field strength is biased to a side where the toner is supplied from the first conveyance member to the second conveyance member, and wherein a time ratio for carrying out a function to collect the toner from the second conveyance member to the first conveyance member is 60 to 80%.