Control method of an electrophotographic record apparatus and image formation apparatus including controlling developing bias and photoconductor surface potential

A control method of an electrophotographic record apparatus comprising:

• detecting a density of a solid test patch image formed on a photoconductor;
• controlling a developing bias so that the density of the solid test patch image reaches a predetermined target value;
• detecting a density of a dot test patch image in a given area percentage formed, the dot test patch image formed on the photoconductor while the control condition of the developing bias is maintained;
• and
• controlling a light application amount in which a dot image is exposed to light so that the sensed density of the dot test patch image becomes constant.

An image formation apparatus comprising:

• a photoconductor;
• a charger for charging the photoconductor;
• a light exposure unit for applying light to the photoconductor for forming an electro static latent image;
• and
• a developing machine for giving a developer to the electrostatic latent image for forming an image on a surface of the photoconductor;
• an image density sensor for detecting a density of an image formed on the photoconductor;
• means for controlling a developing bias of the developing machine in a predetermined value based on an output of the image density sensor so that the sensed density of a solid test patch image formed on the photoconductor reaches a predetermined target value;
• means for forming a dot test patch image in a given area percentage on the photoconductor while the developing bias is controlled in the predetermined value;
• and
• means for controlling the light exposure unit based on output of the image density sensor to expose a dot image, a thin line image, and an edge of a solid image with a light application amount in which the sensed density of the dot test patch image become constant.

An image formation apparatus comprising:

• a photoconductor;
• a charge section for charging a surface of the photoconductor;
• a light exposure section for exposing the photoconductor surface to light in a predetermined light exposure amount for forming an electrostatic latent image;
• a developing section for depositing toner on the photoconductor for developing;
• a detection section for detecting the density of the image provided by the developing section;
• a first control section for determining values of a developing bias applied to the developing section and a surface potential of the photoconductor based on first image density information of a first test image detected by the detection section, the first image developed on the photoconductor by a parallel electric field;
• a second control section for determining the light exposure amount based on second image density information of a second test image detected by the detection section, the second test image developed on the photoconductor by a peripheral electric field;
• and
• a light exposure amount change section for switching a light exposure amount for an image area adjacent to a blank paper portion to the light exposure amount determined by the second control section.

A control method of an electrophotographic record apparatus, comprising:

• controlling a developing bias so that a density of a solid test patch image, formed on a photoconductor, reaches a predetermined target value;
• detecting a density of a dot test patch image, the dot test patch image being formed on the photoconductor while the control condition of the developing bias is maintained;
• and
• controlling a light application amount so that the detected density of the dot test patch image becomes constant.

A control method of an electrophotographic record apparatus, comprising:

• sensing a density of a solid test patch image on a conductive plate;
• controlling a developing bias of the solid test patch image based on the density sensed;
• sensing a density of a dot test patch image formed on the conductive plate while the developing bias is being controlled;
• and
• controlling a light application amount in response to the sensed density of the dot test patch image.

A control apparatus for an image formation device including a photoconductor, comprising:

• a first controller for controlling a developing bias so that a density of a solid test patch image reaches a predetermined target value;
• a detector for detecting a density of a dot test patch image, the dot test patch image being formed on the photoconductor while the first controller is controlling the developing bias;
• and
• a second controller for controlling a light application amount so that the sensed density of the dot test patch image becomes constant.