Removable developing units for a copying machine and display for indicating the useful life of the machine

A developing device for an image-forming machine, said developing device comprising:

• a main body;
• applicator means mounted on the main body for applying a toner to a latent electrostatic image;
• a plurality of toner cartridges adapted to be selectively loaded detachably into the main body;
• loading hampering means responsive to the loading and/or detachment of a predetermined number of the plurality of toner cartridges into and from the main body for assuming a hampering position at which the loading hampering means hampers loading of a toner cartridge into the main body.

An image-forming machine comprising:

• image-forming means including image-bearing means having a surface with electrostatographic material thereon;
• means for forming a latent electrostatic image on said electrostatographic surface;
• a developing device for developing the latent electrostatic image, said developing device including:
• (1) a main body member;
• (2) applicator means mounted on said main body member for applying toner to the latent electrostatic image;
• and
• (3) a plurality of toner cartridges, each toner cartridge adapted to be selectively loaded in a predetermined sequence into said main body member;
• cartridge discriminating means for generating a cartridge discrimination signal indicative of the one of said plurality of toner cartridges loaded in said main body member to indicate the one of said plurality of sequentially loaded toner cartridges that is in said main body member and thus to provide an approximate indication of the remaining useful life of said developing device;
• and
• means for adjusting the image-forming conditions on the basis of the cartridge discrimination signal.

An image-forming machine comprising:

• image-bearing means having a surface with electrostatographic material thereon;
• means for forming a latent electrostatic image on the electrostatographic surface;
• a developing device for developing the latent electrostatic image, said developing device comprising a main body, applicator means mounted on the main body for applying a toner to the latent electrostatic image, and a plurality of toner cartridges adapted to be selectively loaded into the main body;
• first detecting means for producing a cartridge replacement signal when the amount of toner in a toner cartridge loaded into the main body for applying to the latent electrostatic image becomes excessively small;
• second detecting means responsive to detecting of a specified one of the toner cartridges for producing a final cartridge signal;
• and
• life signal producing means responsive to simultaneous production of the cartridge replacement signal and the final cartridge signal for producing a life signal indicating that the life of the electrostatographic material has substantially come to an end.

An image-forming machine comprising:

• image-bearing means having a surface with electrostatographic material thereon;
• means for forming a latent electrostatic image on the electrostatographic surface;
• a developing device for developing the latent electrostatic image, said developing device comprising a main body, applicator means mounted on the main body for applying a toner to the latent electrostatic image, and a plurality of toner cartridges adapted to be selectively loaded into the main body;
• first detecting means for producing a cartridge replacement signal when the amount of toner in a toner cartridge loaded into the main body becomes too small;
• second detecting means responsive to detecting of a selected one of said plurality of toner cartridges for producing a final cartridge signal;
• third detecting means responsive to detection of a number of rotations of the image-bearing member exceeding a predetermined value for producing a rotation signal;
• and
• life signal producing means responsive to simultaneous production of the final cartridge signal and the cartridge replacement signal or simultaneous production of the final cartridge signal and the rotation signal for producing a life signal indicating that the life of the electrostatographic surface has substantially come to an end.