The present invention relates to an image forming apparatus such as a color laser printer.
An image forming apparatus such as a laser printer is generally known, which comprises a plurality of development devices each containing different color toner, a plurality of photoconductor drums each of which is supplied with toner from a corresponding development device via a developing roller, a belt arranged opposite to the plurality of photoconductor drums, and a plurality of transfer devices configured to cause toner retained on the plurality of photoconductor drums to be attracted to the belt. In this image forming apparatus, the plurality of photoconductor drums are arranged in tandem, and a sheet is conveyed on the belt and passes between the plurality of photoconductor drums and the plurality of transfer devices, during which a transfer bias having the reverse polarity of the charged toner is applied to the transfer devices so that different color toner retained on the surfaces of the respective photoconductor drums is attracted by the transfer devices and continuously transferred onto the sheet to perform a color printing on the sheet.
According to this image forming apparatus, in order to ease maintenance of the photoconductor drums, each of the photoconductor drums for different colors is integrally held in a photoconductor drum unit, and this photoconductor drum unit is attached to or detached from a main body of the image forming apparatus. Further, in order to remove adhering substance such as toner and paper dust adhering to the conveyor belt due to sheet jamming, etc., the image forming apparatus is also provided with a cleaning unit configured to contact with the conveyor belt to remove and collect the adhering substance.
For example, Japanese Laid-open Patent Publication No. 2006-98772, which corresponds to US 2006/0067734 A1, discloses an image forming apparatus in which a photoconductor drum unit is arranged above the conveyor belt and a cleaning unit is arranged at a lower position of the conveyor belt where a sheet does not pass through.
An image forming apparatus equipped with a cleaning unit requires maintenance of the cleaning unit in order to dispose of adhering substance that has been removed and collected from the conveyor belt.
However, in the above conventional image forming apparatus, because the cleaning unit is arranged below the conveyor belt, it is necessary to remove the conveyor belt during the maintenance of the cleaning unit. Therefore, the maintenance work becomes complicated and time-consuming.
Further, according to an arrangement where the photoconductor drum unit is arranged above the conveyor belt and the cleaning unit is arranged below the conveyor belt, the height of the image forming apparatus is increased and thus the overall size of the image forming apparatus is enlarged.
In view of the foregoing drawbacks of the prior art, the present invention seeks to provide an image forming apparatus, which can ease the maintenance work of the cleaning unit and which can reduce the overall size of the image forming apparatus.
USPTO Backgrounds
USPTO Backgrounds