Image forming apparatus for controlling developer to be replenished in accordance with density of developer

An image forming apparatus comprising:

• electrostatic latent image forming means for forming an electrostatic latent image on a predetermined area of an image carrier;
• developer supplying means for supplying a developer for developing the electrostatic latent image formed on said image carrier by said electrostatic latent image forming means;
• image transfer means for transferring the image developed by said image developer supplying means onto a recording medium;
• the density detecting means arranged on a portion of said image carrier whereon the electrostatic latent image is not formed, for detecting a developer density of the developer;
• comparing means for comparing a developer density value detected by said developer density detecting means with a reference value;
• and
• stopping means for stopping operations of said electrostatic latent image forming means or said developer supplying means in accordance with a comparison result from said comparing means.

An image forming apparatus for forming an electrostatic latent image in a predetermined area on an image carrier, comprising:

• developer supplying means, including a developing unit for storing developer to be used in developing the electrostatic latent image formed on said image carrier by said electrostatic latent image forming means, and developer replenishing means for storing replenishment developer therein and replenishing the developer;
• image transfer means for transferring the image developed by said developer supplying means onto a recording medium;
• developer density optical detecting means comprising a light-emitting element for radiating light onto said image carrier, said light emitting element being arranged to radiate on a portion of said image carrier on which the electrostatic latent image is not formed and located outside of said developing unit, and a light-receiving element for receiving the light radiated from said light-emitting element and reflected by said image carrier, said developer density optical detecting means optically detecting the density of the developer;
• first comparing means for comparing the developer density value optically detected by said developer density optical detecting means with a first reference value, said first reference value setting a reference density of the developer;
• second comparing means for comparing the developer density value optically detected by said developer density optical detecting means with a second reference value, said second reference value representing that said developer replenishing means is empty;
• and
• stopping means for stopping operations of said latent image forming means, said image transfer means, or said developer replenishing means, in accordance with a comparison result from said second comparing means.

An image forming apparatus comprising:

• an image carrier having an image forming area and a reference image forming area;
• latent image forming means for forming an electrostatic latent image in the image forming area and an electrostatic latent reference image in the reference image forming area;
• developer supplying means for supplying developer to both the electrostatic latent image and the electrostatic latent reference image on said image carrier;
• developer density detecting means for photoelectrically detecting the density of the developer developing the electrostatic latent reference image formed on said image carrier to obtain a density signal having a value corresponding to the density of the developer;
• comparing means for comparing the value of the density signal with a reference value;
• and
• stopping means for stopping operations of said developer supplying means when it is determined that the value of the density signal is less than the reference value.

An image forming apparatus comprising:

• an image carrier having an image forming area and a reference image forming area;
• latent image forming means for forming an electrostatic latent image at the image forming area and an electrostatic latent reference image at the reference image forming area;
• developer supplying means for supplying developer to both the electrostatic latent image and the electrostatic latent reference image on said image carrier;
• developer density detecting means for photoelectrically detecting the density of the developer supplied to the electrostatic latent reference image, to obtain a density signal having a value corresponding to the density of the developer;
• first comparing means for comparing the value of the density signal with a first reference value,
• second comparing means for comparing the value of the density signal with a second reference value, which is smaller than the first reference value;
• and
• control means for respectively driving said developer supplying means to replenish the developer or stopping operation of the developer, depending on the value of the density signal.

An image forming apparatus comprising:

• means for supplying developer to an image carrier;
• means for detecting the density of the developer;
• first comparing means for comparing the developer density value detected by said detecting means with a first reference value;
• second comparing means for comparing the developer density value detected by the detecting means with a second reference value which is less than the first reference value;
• means for replenishing the developer in the supplying means when the comparison from the first and second comparing means indicates that the detected toner density is smaller than the first reference value and larger than the second reference value;
• and
• means for stopping the operation of the supplying means when the comparison from the second comparing means indicates that the detected toner density is smaller than the second reference value.