Development device, process cartridge, image forming apparatus incorporating same, and developer amount adjustment method therefor

A development device to develop a latent image formed on a latent image bearer with two-component developer contained therein, the development device comprising:

• a partition dividing, at least partly, an interior of the development device into a supply channel and a collection channel;
• a developer bearer to carry developer and disposed facing the latent image bearer;
• a developer regulator to adjust an amount of developer carried on the developer bearer;
• and
• multiple developer conveyance members to transport developer in a longitudinal direction of the development device and circulate developer therein, the multiple developer conveyance members including first and second conveyance members disposed facing the developer bearer,
• the first developer conveyance member to supply developer to the developer bearer,
• the second developer conveyance member to transport developer collected from the developer bearer in the collecting channel,
• wherein the development device is operable in multiple different speed modes and performs developer amount balance adjustment in which a driving velocity of at least the multiple developer conveyance members is increased from a driving velocity in a lower-speed mode, and
• the development device executes the developer amount balance adjustment for a predetermined period after image development in the lower speed mode is completed and before image development in a higher speed mode is started.