Introduction to classification
Copier according to the working principle, the copier can be divided into photochemical copy, thermal copy, electrostatic copy and digital laser copy four categories.
Photochemical copy has direct photocopying, blueprint copying, diazo copying, dye transfer and diffusion transfer and other methods. Direct photocopying method with high contrast photo paper instead of photographic film on the original photography, can increase or shrink; blueprint method is coated with iron coated surface, the original is a single sheet of translucent material, both stacked together to accept exposure, development After the formation of blue-white image; diazo method and blueprint method similar to the copy paper coated with diazo compounds, exposure in liquid or gas ammonia in the development, resulting in dark hue image; dye transfer method is the original and the surface coating The translucent negative film of the photosensitive emulsion is put together, and then exposed to the liquid and then transferred to the paper. The diffusion transfer method is similar to the dye transfer method. After the exposure, the negative film is affixed with the copy paper coated with the film , The silver salt on the negative film after the liquid development spreads onto the copy paper to form a black image.
Thermal copy is the surface coated with heat-sensitive material of the copy paper, with a single original sheet attached to accept infrared or heat source exposure. The heat absorbed by the image part is transferred to the surface of the copy paper so that the color tone of the heat-sensitive material becomes darker to form a copy. This copy method is mainly used for fax machines to receive faxes.
The use of material photoconductive phenomena and electrostatic phenomena combined with the principle of copying. Commonly used photoreceptors are cartridges, zinc oxide paper, cadmium sulfide drums and organic light conductor tape. Copying methods are indirect and direct.
The indirect electrostatic copying step (see figure) is: first with high-pressure corona discharge so that the photoreceptor surface in the dark charge on the static charge; and then the original exposure, exposure part of the static charge disappeared, the rest of the static charge to retain the formation of the naked eye The electrostatic image of the electrostatic latent image; and then the developer to develop the electrostatic latent image into a visible toner image; the toner image is transferred to plain paper, the toner is melted and fused on the paper to obtain a copy The After the copy of the fixed and ordinary printed as long-term preservation. Remove the toner remaining on the photoreceptor after the transfer, and the cleaned photoreceptor can be used immediately. Directly electrostatic photocopying of the photoreceptor for the zinc oxide paper, the final image directly on the paper, without transfer and cleaning.