| Q1: In regard to photosensitive materials, what is the difference between visible light material and near-infrared material? |
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A1: When near-infrared light (laser of 700nm or greater) is used as the exposure light source, incident light and light reflecting from the substrate surface interfere with each other, which generates interference patterns on the image. To prevent this, near-infrared photosensitive material has two additional characteristics as compared to visible light material.
1) A light-absorption layer (to absorb incident and reflected light)
2) A roughened substrate surface (to scatter the reflected light)
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| Q2: Once an image is exposed and printed, how is it erased from the imaging engine? |
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A2: A light image of the previous pattern — called a "residual image" or "ghost" — remains on the photosensitive material during its next rotation. This is caused when part of the carriers generated by the exposed portion are trapped inside the layer, so they cannot reach the outer surface before the next process. Ghosting tends to become more of a problem at longer wavelengths, which cause light to penetrate the photosensitive material more deeply. The process of erasing can overcome this problem. To erase the residual image properly, it is necessary to select a wavelength that is close to, but actually slightly shorter than, the exposure wavelength.
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| Q3: Why is there no high-charge type of near-infrared material available? |
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A3: Because of its thicker layer, high-charge material is more than twice as chargeable as standard material. The portion of the carriers generated by the erase light trapped inside the layer are moved to the surface by the strong electric field following the charging process, which neutralizes the surface charge. The longer the wavelength, the deeper the light penetrates, and the greater the volume of carriers that become trapped, leading to a noticeable drop in charging. In the case of a long-wavelength exposure system that requires use of a long-wavelength erase light (described in Q2, above), the long-wavelength erase light increases the drop in charging. At the current state of the technology, it is difficult to improve chargeability further by making the layer thicker.
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| Q4: What indicates the end of a photoconductive material’s service life? |
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A4: A photoconductive material has reached the end of its service life when friction begins to cause wear on the surface, deteriorating the material's characteristics and reducing print performance. Kyocera’s amorphous-silicon (a-Si) imaging drum has a very hard surface protection layer, which limits wear to a level less than half a micron after printing three million sheets.
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| Q5: Is the photoconductive material reusable? |
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A5: The aluminum substrate is reusable. The layer is nontoxic, so there is no special handling required when disposing of it.
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| Q6: Is the a-Si drum available with non-standard custom specifications? |
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A6: Yes. Since the a-Si drum is custom made, customers can specify size, layer specifications (characteristics), and shipping configuration.
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| Q7: Can a-Si photoconductive material be produced in belt form? |
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A7: With an a-Si semiconductor, the application of extreme pressure can cause the layer network to break, resulting in a loss of semiconductive characteristics, and therefore making a belt configuration unrealistic at this point. However, since some photovoltaic cells and other related devices are being manufactured in sheet form, we cannot rule out such a possibility for the future.
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| Q8: Can materials other than aluminum be used for the substrate? |
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A8: Though aluminum is the ideal substrate material from the viewpoint of layer adhesion, please feel free to contact Kyocera concerning specific inquiries about using other materials.
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| Q9: Are specifications available? |
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| A9: Though there are standard specifications that cover external appearance and electrical characteristics, other characteristics depend on customer specifications for each custom design. |
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