Image forming apparatus for controlling the dynamic range of an image

An image forming equipment for electrostatically forming a latent image on a photoconductive element and developing the latent image by a developer containing at least a toner to produce a corresponding toner image on the photoconductive element, the equipment comprising:

• a) developing means including a developing sleeve for forming a predetermined toner image pattern on the photoconductive element;
• b) photosensor means for sensing a reflection from the predetermined toner image pattern;
• and
• c) control means for changing at least one of:
• 1) a developing bias;
• 2) a charge potential;
• 3) a quantity of exposing light;
• and
• 4) a quantity of toner supply;
• in response to the output signal of the photosensor means representative of a reflection incident to the photosensor means, wherein the control means includes:
• 1) means for comparing with a predetermined value a greater of:
• i) a background output VSG+ of the photosensor means representative of a reflection from a non-image area of the photoconductive element and appearing when the developing sleeve is not rotating and the photoconductive element is rotating;
• and
• ii) a background output VSG of the photosensor means representative of a reflection from the photoconductive element and appearing when the developing sleeve is rotating and the photoconductive element is rotating;
• and
• 2) means for controlling the quantity of toner supply on the basis of the result of comparison of the means for comparing.

An image forming equipment for electrostatically forming a latent image on a photoconductive element and developing the latent image by a developer containing at least a toner to produce a corresponding toner image on the photoconductive element, the equipment comprising:

• a) developing means including a developing sleeve for forming a predetermined toner image pattern on the photoconductive element;
• b) photosensor means for sensing a reflection from the predetermined toner image pattern;
• and
• c) control means for changing at least one of:
• 1) a developing bias;
• 2) a charge potential;
• 2) a quantity of exposing light;
• and
• 4) a quantity of toner supply;
• in response to the output signal of the photosensor means representative of a reflection incident to the photosensor means, wherein the control means includes:
• 1) means for calculating a difference between:
• i) a background output VSG+ of the photosensor means representative of a reflection from a non-image area of the photoconductive element and appearing when the developing sleeve is not rotating and the photoconductive element is rotating;
• and
• ii) a background output VSG of the photosensor means representative of a reflection from the photoconductive element and appearing when the developing sleeve is rotating and the photoconductive element is rotating;
• 2) means for calculating a gradient of changes of a plurality of background outputs VSG, when the difference calculated by the means for calculating is smaller than a predetermined value;
• and
• 3) means for variably controlling a dynamic range of an electrostatic latent image on the basis of the gradient.

An image forming equipment for electrostatically forming a latent image on a photoconductive element and developing the latent image by a developer containing at least a toner to produce a corresponding toner image on the photoconductive element, the equipment comprising:

• a) developing means including a developing sleeve for forming a predetermined toner image pattern on the photoconductive element;
• b) photosensor means for sensing a reflection from the predetermined toner image pattern;
• and
• c) control means for changing at least one of:
• 1) a developing bias;
• 2) a charge potential;
• 3) a quantity of exposing light;
• and
• 4) a quantity of toner supply;
• in response to the output signal of the photosensor means representative of a reflection incident to the photosensor means, the control means including:
• 1) means for calculating a first gradient of changes of a plurality of background outputs VSG representative of reflections from the photoconductive element and appearing when the developing sleeve is rotating;
• 2) means for determining whether or not the equipment is in an unusual state on the basis of the first gradient;
• and
• 3) means for calculating a second gradient of changes of a greater number of background outputs VSG than the plurality of background outputs VSG, if the equipment is not in an unusual state;
• and
• 4) means for determining whether or not the equipment is in an unusual state on the basis of the second gradient.

An image forming equipment for electrostatically forming a latent image on a photoconductive element and developing the latent image by a developer containing at least a toner to produce a corresponding toner image on the photoconductive element, the equipment comprising:

• a) developing means including a developing sleeve for forming a predetermined toner image pattern on the photoconductive element;
• b) photosensor means for sensing a reflection from the predetermined toner image pattern;
• and
• c) control means for changing at least one of:
• 1) a developing bias;
• 2) a charge potential;
• 3) a quantity of exposing light;
• and
• 4) a quantity of toner supply;
• in response to the output signal of the photosensor means representative of a reflection incident to the photosensor means, the control means including:
• 1) means for determining whether the equipment is in an unusual state, the determining occurring when each of the following outputs i) and ii) has a gradient greater than a predetermined value:
• i) a background output VSG+ of the photosensor means representative of a reflection from a non-image area of the photoconductive element and appearing when the developing sleeve is not rotating and the photoconductive element is rotating;
• and
• ii) a background output VSG of the photosensor means representative of a reflection from the photoconductive element and appearing when the developing sleeve is rotating and the photoconductive element is rotating;
• and
• 2) means for determining that the equipment is in an unusual state.