Image forming apparatus having detection of residual toner amount

An image forming apparatus comprising:

• (i) an apparatus body;
• (ii) an image bearing member on which an image is formed;
• and
• (iii) a process unit attached to the apparatus body, the process unit including:
• (iii-i) a frame including a storage portion configured to store developer;
• (iii-ii) a developer bearing member configured to bear the developer and to supply the developer to the image bearing member to develop an electrostatic latent image, the developer bearing member being supported by the frame;
• (iii-iii) a light emitting portion configured to emit light, the light emitting portion being one of an LED, a halogen lamp, and a fluorescent lamp;
• and
• (iii-iv) a light receiving portion configured to receive light emitted from the light emitting portion and having passed through an interior of the storage portion, the light receiving portion being one of a phototransistor and a photodiode,
• wherein the light emitting portion and the light receiving portion are supported by the frame and are arranged on a side of a surface, of the frame, that is opposite from a side of the developer bearing member in a direction perpendicular to a longitudinal direction of the developer bearing member, the light emitting portion and the light receiving portion being provided at a center portion of the storage portion of the frame with respect to the longitudinal direction of the developer bearing member.

A process unit used in an image forming apparatus, the process unit comprising:

• a frame including a storage portion configured to store developer;
• a developer bearing member configured to bear the developer, the developer bearing member being supported by the frame;
• and
• a circuit board attached to the frame,
• wherein the circuit board includes:
• a light emitting portion configured to emit light;
• and
• a light receiving portion configured to receive the light emitted from the light emitting portion and having passed through an interior of the storage portion, the light emitting portion and the light receiving portion being provided at a center portion of the storage portion of the frame with respect to a longitudinal direction of the developer bearing member.

A process unit used in an image forming apparatus, the process unit comprising:

• a frame including a storage portion configured to store developer;
• a developer bearing member configured to bear the developer, the developer bearing member being supported by the frame;
• a light emitting portion configured to emit light, the light emitting portion being one of an LED, a halogen lamp, and a fluorescent lamp;
• and
• a light receiving portion configured to receive light emitted from the light emitting portion and having passed through an interior of the storage portion, the light receiving portion being one of a phototransistor and a photodiode,
• wherein the light emitting portion and the light receiving portion are supported by the frame and are arranged on a side of a surface, of the frame, that is opposite from a side of the developer bearing member in a direction perpendicular to a longitudinal direction of the developer bearing member, the light emitting portion and the light receiving portion being provided at a center portion of the storage portion of the frame with respect to the longitudinal direction of the developer bearing member.