Patent ID: 6483998
Filing Date: 2002-11-19
Classification: G03G

Abstract:
An image-forming apparatus for forming an image by electrically charging a photosensitive material, forming an electrostatic image through the exposure to light and developing the electrostatic image, wherein the main charged potential, Vo, of the photosensitive material, the potential, Vr, of the exposed portion of the photosensitive material and the developing bias potential DB are so set as to satisfy the following formulas (1) and (2),V1&lE;|DBâˆ’Vr|&lE;V2â€ƒâ€ƒ(1) V3&lE;|Voâˆ’DB|&lE;300â€ƒâ€ƒ(2) wherein V1, V2 and V3 are parameters calculated from a developing characteristics curve obtained by plotting the image densities to a potential difference between the developing bias potential and the surface potential, 0 V, of the photosensitive material when the image is formed by changing the developing bias potential with the exposure amount being zero in a state where the potential on the surface of the photosensitive material is maintained at zero, V1 being a potential difference, absolute value, at a point at where an approximated straight line A in a region where the image density linearly increases intersects an approximated straight line B in a region where the image density increases to its saturation on the developing characteristics curve; V2 being a potential difference absolute value, at a point where the approximated straight line B separates away from the developing characteristics curve; and V3 being a potential difference, absolute value, at a point at where the image density exhibits a value of base paper density+0.005.