Image density control apparatus and method for controlling image density on a photoconductor surface

An image density control apparatus for controlling an image density on a photoconductor surface, comprising:

• charging means for charging said photoconductor surface uniformly;
• forming means, by a scanning of a laser beam from a laser source, for forming a standard latent image having an electric potential distribution on said photoconductor surface;
• first detection means for detecting an electric potential distribution of said standard latent image;
• developing means for developing a standard toner image from said standard latent image;
• second detection means for detecting a density of said standard toner image;
• and
• selection means for selecting a gradation correction table in accordance with the detected electric potential distribution and the detected density.

A method for controlling an image density on a photoconductor surface by selecting a gradation table from a plurality of gradation tables stored in a memory comprising the steps of:

• charging said photoconductor surface uniformly;
• forming, by scanning a laser beam, a latent image having an electric potential distribution on said uniformly charged photoconductor surface;
• detecting said electric potential distribution of said latent image;
• calculating an electric potential difference between a maximum electric potential and a minimum electric potential in the electric potential distribution;
• determining a relationship between density of an image and the gradation tables in accordance with said electric potential difference;
• charging said photoconductor surface uniformly again;
• forming, by the scanning of the laser beam, a standard latent image;
• developing said standard latent image;
• detecting a density of said developed standard toner image;
• and
• selecting a gradation correction table in accordance with the density of the standard toner image by using the determined relationship.