Patent ID: 8588627
Filing Date: 2013-11-19
Classification: G03G

Abstract:
1. An image forming apparatus comprising: an image carrying member; a developing device that develops an electrostatic latent image on the image carrying member by using a toner; a controller that switches between a first toner empty stop condition and a second toner empty stop condition are in response to the state of the device, wherein said first toner empty stop condition and said second toner empty stop condition for prohibiting printing because of a lack of the remaining amount in the toner are provided; a toner cartridge that contains toner and is replaceably fitted to a body of the image forming apparatus; a sub hopper that is placed between said toner cartridge and said developing device to deliver the toner of said toner cartridge to said developing device; a first unit that replenishes the toner from said toner cartridge to said sub hopper; a second unit that replenishes the toner from said sub hopper to said developing device; a sub hopper remaining amount detection unit that detects a toner remaining amount in said sub hopper; and a toner concentration detection unit that detects the toner concentration in said developing device; wherein: said first toner empty stop condition is judged by said sub hopper remaining amount detection unit depending on the fact that said sub hopper is vacant; and said second toner empty stop condition is judged by said toner concentration detection unit after said sub hopper is vacant depending on the fact that the toner concentration in said developing device is not more than a predetermined value.