Kyocera Corporation

Tadashi Ohba

Keiji Itsukushima

Hisashi Higuchi

Norio Tomiie

Jun Nakai

When intending gradational representation of each of the dots composing the image by changing the amount of light emission of each of the dots composing an image by changing the amount of light emission of said light emitting diode, the magnitude of each of the dots becomes reduced resulting in unstable reproducibility of dot. This causes damage in the regularity of the distribution of image density and the graininess of the printed image increases. The invention aims to provide an image forming apparatus which can decrease granularity (graininess) by simple and inexpensive construction by defocusing on the photo conductor the light ray passing through the lens array of the exposing device in the image forming apparatus in accordance with the percentage of the luminous dots changed in the amount of light emission among the dots composing the image. This prevents the occurrence of irregular density distribution in the latent image on the photo conductor drum. As a result, the graininess of the printed image is decreased.

Image forming apparatus

An electrophotographic apparatus using an a-Si photosensitive drum. The a-Si photosensitive drum has a thickness between 2 and 25 .mu.m. The initial charging potential on the photosensitive drum is set to 450V or below. The center exposure wavelength of an exposure means is set to 700 nm or above. The photosensitive drum includes a photoconductive layer formed as a thin film a-Si layer having a temperature characteristic of 1.0 V/.degree.C. or below. For realizing low charging potential and low electric field development, the thickness d of the photoconductive layer in the photosensitive drum is set to 2 to 24 .mu.m, the relative dielectric constant .epsilon.r is set to 2 or above, and the ratio d/.epsilon.r is set to 9 or below. The photosensitive drum is formed on a conductive support and has a three-layer structure, including a carrier charge blocking layer for blocking the introduction of carrier charge (of the opposite polarity to that of charging) from the conductive support into the photoconductive layer, a photoconductive layer and an insulating or high resistivity layer.

Growing community of inventors

Kyoto, Japan

Tadashi Ohba