Development device and image forming apparatus incorporating same

A development device comprising:

• a cylindrical developer bearer to carry by rotation two-component developer including toner and magnetic carrier particles to a development range where the developer bearer faces a latent image bearer;
• a magnetic field generator disposed inside the developer bearer for generating magnetic force;
• a developer regulator disposed upstream from the development range in a rotational direction of the developer bearer and facing a circumferential surface of the developer bearer across a regulation gap for adjusting an amount of the developer carried by the developer bearer to the development range;
• a supply compartment disposed adjacent to the developer bearer, from which the developer is supplied to the developer bearer and in which the developer removed from the developer bearer by the developer regulator is collected, the supply compartment partially separated by a side wall from a portion where the developer bearer is provided,
• a developer agitator provided in the supply compartment for transporting the developer in an axial direction of the developer bearer;
• and
• a blocker disposed facing an upper end of the side wall of the supply compartment across a supply gap through which the developer moves from the supply compartment toward the developer bearer, the supply gap extending at least over an entire development range in the axial direction of the developer bearer,
• wherein the magnetic field generator has an attraction magnetic pole for generating an attraction magnetic force to attract the developer from the supply compartment beyond the upper end of the side wall of the supply compartment to the circumferential surface of the developer bearer as well as a regulation magnetic pole for generating a regulation magnetic force to cause the developer passing through the regulation gap to stand on end on the circumferential surface of the developer bearer, the regulation magnetic pole adjacent to the attraction magnetic pole and having a polarity opposite a polarity of the attraction magnetic pole, and
• the blocker prevents the developer blocked by the developer regulator from moving toward the circumferential surface of the developer bearer along a magnetic force line of the regulation magnetic force.