Image forming apparatus and toner cartridge therefor

A toner cartridge comprising:

• a developer storage container for storing a developer;
• a rotary conveyance body, arranged in said developer storage container, for carrying a developer in the storage container toward an exhaust port;
• and
• detection windows through which a light beam projected from a developer detector is input and output to detect the remaining state of the developer in the toner cartridge when the toner cartridge is mounted to a developing unit, wherein
• said detection windows are arranged such that the optical axis of the input and output light beam becomes parallel to a direction that said rotary conveyance body carries the developer.

An image forming apparatus comprising:

• a toner cartridge for storing a developer, which comprises a rotary conveyance body for carrying the stored developer toward an exhaust port;
• an image carrier having a latent image formed thereon and holding a developer image developed with the developer;
• a developing unit for developing the latent image formed on the surface of the image carrier;
• and
• a developer detector having a light beam projecting unit and a light beam receiving unit to detect the remaining state of the developer in said toner cartridge, wherein
• said toner cartridge has detection windows through which a light beam projected from said developer detector is input and output when the toner cartridge is mounted to the developing unit;
• and
• said detection windows are arranged at positions where the optical axis of the input and output light beam intersects the rotary shaft of said rotary conveyance body obliquely on a projection plane when seen from the top or side of the toner cartridge.

An image forming apparatus comprising:

• a toner cartridge for storing a developer, which comprises a rotary conveyance body for carrying the stored developer toward an exhaust port;
• an image carrier having a latent image formed on the surface and holding a developer image developed with the developer:
• a developing unit for developing the latent image formed on the surface of the image carrier;
• and
• a developer detector having a light beam projecting unit and a light beam receiving unit, for detecting the remaining state of the developer in said toner cartridge, wherein
• said toner cartridge has detection windows through which a light beam projected from said developer detector is input and output when the toner cartridge is mounted to the developing unit;
• and
• said detection windows are arranged such that the optical axis of the input and output light beam becomes parallel to a direction that said rotary conveyance body carries the developer on a projection plane when seen from the top or side of the toner cartridge.