Developer cartridge for developing a latent image detachably mountable to a main assembly of an image forming apparatus

A developing cartridge for developing a latent image formed on an electrophotographic photosensitive member, wherein said developing cartridge is detachably mountable to a main assembly of an electrophotographic image forming apparatus, said developing cartridge comprising:

• a developing roller for developing a latent image formed on the electrophotographic photosensitive member with toner;
• a developing bias contact for receiving a developing bias to be supplied to said developing roller from the main assembly when said developing cartridge is mounted to the main assembly, said developing bias contact being exposed at one longitudinal end of said developing cartridge;
• a toner accommodating portion for accommodating the toner to be used by said developing roller;
• first and second light transmitting portions provided in said toner accommodating portion, wherein said first light transmitting portion and said second light transmitting portion are disposed at positions closer to the longitudinal end where said developing bias contact is provided than the opposite longitudinal end;
• a first light guide for directing, to said first light transmitting portion, light emitted by a light emission member provided in the main assembly, wherein one end of said light guide is opposed to said first light transmitting portion, and the other end thereof is exposed at the end where said developing bias contact is provided;
• and
• a second light guide for directing the light having passed through said second light transmitting portion to a light receiving element provided in the main assembly, wherein one end of said second light guide is opposed to said second light transmitting portion, and the other end thereof is exposed at the end of said developing cartridge where said developing bias contact is provided, and wherein when said developing cartridge is mounted to the main assembly, said second light guide is positioned above said first light guide.

An electrophotographic image forming apparatus for forming an image on a recording material, to which a developing cartridge is detachably mountable, comprising:

• (a) a light emission member;
• (b) a light receiving member;
• (c) a main assembly developing bias contact;
• (d) a mounting member for mounting a developing cartridge, which includes:
• a developing roller for developing a latent image formed on an electrophotographic photosensitive drum with toner;
• a developing bias contact for receiving a developing bias to be supplied to said developing roller from a main assembly of said electrophotographic image forming apparatus when the developing cartridge is mounted to the main assembly, said developing bias contact being exposed at one longitudinal end of the developing cartridge;
• a toner accommodating portion for accommodating the toner to be used by said developing roller;
• first and second light transmitting portions provided in said toner accommodating portion, wherein said first light transmitting portion and said second light transmitting portion are disposed at positions closer to a longitudinal end where said developing bias contact is provided than the opposite longitudinal end;
• a first light guide for directing, to said first light transmitting portion, light emitted by said light emission member, said light emission member being provided in the main assembly, wherein one end of the first light guide is opposed to the first light transmitting portion, and the other end thereof is exposed at the end where said developing bias contact is provided;
• and
• a second light guide for directing the light having passed through said second light transmitting portion to said light receiving elements said light receiving element being provided in the main assembly, wherein one end of said second light guide is opposed to said second light transmitting portion and the other end thereof is exposed at an end of said developing cartridge where said developing bias contact is provided, and wherein when said developing cartridge is mounted to the main assembly, said second light guide is positioned above said first light guide;
• said apparatus further comprising:
• (e) a feeding member for feeding the recording material.