Abstract: A large number of holes are formed in a two-layered porous film sandwiched between a lower substrate and an upper substrate and filled with a light transmitting liquid and fine particles. When a voltage is applied between an upper electrode and a lower electrode, migration of the fine particles, takes place based on electrophoresis. White color is displayed when the fine particles are located on an upper transparent porous film side and black color is displayed when the fine particles are located on a lower black porous film side. Color display is also possible by periodically repeating three primary colors of RGB in the lower layer porous film or arranging a color filter on the transparent upper substrate. Bubbles-containing fine particles or bubbles themselves may be employed in place of the fine particles.

Abstract: A large number of holes are formed in a two-layered porous film sandwiched between a lower substrate and an upper substrate and filled with a light transmitting liquid and fine particles. When a voltage is applied between an upper electrode and a lower electrode, migration of the fine particles, takes place based on electrophoresis. White color is displayed when the fine particles are located on an upper transparent porous film side and black color is displayed when the fine particles are located on a lower black porous film side. Color display is also possible by periodically repeating three primary colors of RGB in the lower layer porous film or arranging a color filter on the transparent upper substrate. Bubbles-containing fine particles or bubbles themselves may be employed in place of the fine particles.

Abstract: When a halftone image region that is below a predetermined density is to be reproduced, a processing unit controlling an exposure unit selects an exposure pattern that can represent a record dot diameter within a range based on a predetermined rule from exposure patterns prepared in advance. Accordingly, graininess is suppressed. When there are a plurality of exposure patterns that can be applied, the exposure pattern with the lowest number of dots present per 1 inch is employed. Accordingly, a halftone image is formed with the image reproducibility improved.

Abstract: When a halftone image region that is below a predetermined density is to be reproduced, a processing unit controlling an exposure unit selects an exposure pattern that can represent a record dot diameter within a range based on a predetermined rule from exposure patterns prepared in advance. Accordingly, graininess is suppressed. When there are a plurality of exposure patterns that can be applied, the exposure pattern with the lowest number of dots present per 1 inch is employed. Accordingly, a halftone image is formed with the image reproducibility improved.

Abstract: In a digital electrophotographic imaging process in which a latent electrostatic image is written to a charged photoreceptor using an exposure beam diameter Ds larger than pixel pitch Dp and the image is visualized by development, an unsaturated region of photo-induced discharge characteristics of the photoreceptor is used for an image portion of isolated 1 line, and a saturated region of the photo-induced discharge characteristics of the photoreceptor or gamma characteristics of development is used for an image portion for n lines (n≧2).

Abstract: An exposure apparatus for image formation uses power control means provided to a laser driver for controlling exposure energy and accordingly forming an image. Specifically, exposure energy is varied depending on an isolated-dot pattern and an isolated-line pattern by changing the pulse height (drive power) of a drive pulse for each dot. Both of the isolated-line and isolated-dot patterns of a high resolution can thus be reproduced with a high image quality without increase of cost due to requirements for accuracy in processing and positioning of a lens and without decrease of life of a photoreceptor due to a decreased thickness of its photosensitive layer.

Abstract: A control unit of an image forming apparatus for controlling exposure energy includes a reference image storage unit storing a plurality of reference images, an image recognition unit comparing image information consisting of a plurality of pieces of pixel information with data stored in the reference image storage unit, an exposure energy density storage unit storing an exposure energy density for each reference image stored in the reference image storage unit, an exposure energy density determination unit based on data from the image recognition unit and data in the exposure energy density storage unit an exposure energy density to be applied to a dot position corresponding to each piece of the pixel information, and a laser drive driving a laser of an exposure unit based on data from the exposure energy density determination uni. Accordingly, the image forming apparatus can be provided which exhibits an excellent image reproducibility for images with various dot densities.

Abstract: In a digital electrophotographic imaging process in which a latent electrostatic image is written to a charged photoreceptor using an exposure beam diameter Ds larger than pixel pitch Dp and the image is visualized by development, an unsaturated region of photo-induced discharge characteristics of the photoreceptor is used for an image portion of isolated 1 line, and a saturated region of the photo-induced discharge characteristics of the photoreceptor or gamma characteristics of development is used for an image portion for n lines (n≧2).

Abstract: An image forming apparatus has the following characteristics: the diameter of an exposure beam for exposing a latent image is not more than twice a minimum dot recording period p in peak intensity 1/e2, and the value of a spatial frequency characteristic function of a latent image defined by the thickness of a photoreceptor layer, the dielectric constant of the photoreceptor layer, the thickness of a developer layer, the dielectric constant of the developer layer and a spatial frequency &ohgr; defined as &ohgr;=&pgr;/p is at least 0.3. The image forming apparatus having such characteristics can reproduce an image of high resolution exceeding 600 to 1200 DPI with high fidelity.

Abstract: An exposure apparatus for image formation uses power control means provided to a laser driver for controlling exposure energy and accordingly forming an image. Specifically, exposure energy is varied depending on an isolated-dot pattern and an isolated-line pattern by changing the pulse height (drive power) of a drive pulse for each dot. Both of the isolated-line and isolated-dot patterns of a high resolution can thus be reproduced with a high image quality without increase of cost due to requirements for accuracy in processing and positioning of a lens and without decrease of life of a photoreceptor due to a decreased thickness of its photosensitive layer.

Abstract: It is an object of the invention that development quality is improved by increasing the amount of charge during the transportation of toner by a toner holding member and decreasing the amount of charge during development for rendering an electrostatic latent image visible. A one-component non-magnetic toner is supplied from a toner supplying unit to the toner holding member such that the toner is electrostatically attracted to adhere to the toner holding member with a large amount of charge. The charge of the toner under transportation is reduced by charge adjusting means such as a conductive roller supplied with a potential from a frictional charging member or a voltage source, whereby the amount of development or the amount of toner adhering to an electrostatic latent image is increased and development quality is improved.

Abstract: An exposure energy control unit of an image forming apparatus controls exposure energy density Edot (&mgr;J/cm2) to be applied to an isolated one-dot pattern of image information to satisfy a relation −0.11P+6.4≦Edot/Eline≦−0.2P+10.7 where Eline (&mgr;J/cm2) represents exposure energy density applied to a line pattern of the image information having lines on every second lines and P (&mgr;m) represents dot pitch. Accordingly, image reproducibility of both of a periodic line pattern and an isolated dot pattern can be enhanced without decreasing the film thickness of a photoreceptor even if the resolution is high.