User manual CANON LBP-1120

[. . . ] 2002 COPYRIGHT © 2002 CANON INC. FY8-13HT-000 CANON LBP-1120 REV. 0 MAY. 2002 PRINTED IN JAPAN (IMPRIME AU JAPON) Application This manual has been issued by Canon Inc. for qualified persons to learn technical theory, installation, maintenance, and repair of products. For this reason, there may be information in this manual that does not apply to your locality. [. . . ] The toner functions as an insulator, and acquires a negative charge by friction due to the rotating cylinder. The areas on the drum that were exposed to the laser beam have a higher potential (are less negative) than the negatively charged toner particles on the developing cylinder. When these areas approach the toner layer of the cylinder (with negative charges), the potential difference (higher on the drum) projects the toner particles to them. This is called toner projection development, which develops the latent image on the drum into a visible image. Developing cylinder surface potential +V Voltage (V) 0 Drum surface potential (Lightarea) DC bias Drum surface potential (Darkarea) -V Time (t) Figure 2-4-9 2 - 27 CHAPTER 2 An AC bias is applied to the developing cylinder to help project the toner particles to the drum surface and improve the contrast of the printed image. The center voltage of the AC bias (1460 Vp-p) varies with the developing DC bias. This printer changes the developing DC bias value according to the IMAGE DENSITY DATA signal sent from the interface controller. The changes of the developing DC bias value makes the potential difference between the cylinder and drum so that the density of the print can be adjusted. Transfer Stage In the transfer stage, the toner image is transferred from the drum surface onto the paper. Step 4: Transfer Photosensitive drum Paper Transfer charging roller Figure 2-4-10 Positive charges are applied to the back of the paper to attract the negatively charged toner particles to the paper. Step 5: Separation Photosensitive drum Paper e Static charg eliminator Transfer charging roller Figure 2-4-11 The elasticity of the paper causes it to separate from the drum (curvature separation). To stabilize the paper feed system and to prevent droplets on the printed image at low temperature and low humidity, the charge on the back of the paper is reduced by the static charge eliminator. 2 - 28 CHAPTER 2 4. Fixing Stage As the toner image transferred onto the paper in the transfer stage is held to the paper only by the static electricity, even a light touch will smear the image. The toner particles are fused to the paper to make a permanent image by applying pressure and heat to the paper and toner. Step 6: Fixing Fixing film Toner Fixing film Fixing heater Toner Paper Pressure roller Paper Pressure roller Figure 2-4-12 As the toner particles transferred onto the paper are held to the paper by the positive charge applied to the back of the paper, they may be dispersed at fixing. This printer applies the negative DC voltage to the fixing film via the pressure roller shaft. The negative charge is applied to the paper surface by the fixing film before the paper reaches the fixing heater. This improves the adhesion force of the toner particles to the paper and prevents dispersion of the toner particles. This printer utilizes an on-demand fixing method which uses the fixing film that requires small heat capacity. This method can heat the roller quickly and does not require the power supply to the fixing heater at the standby mode. Therefore, the wait time is reduced to eight seconds or less, and the energy can be saved. The surface is coated with fluorine to prevent offset. 2 - 29 CHAPTER 2 5. Photosensitive Drum Cleaning Stage At the photosensitive drum cleaning stage, the photosensitive drum surface is cleaned in preparation for the next print operation. [. . . ] When multiple errors occur, an error with the highest priority will be indicated first. When the first error is cleared, then an error with the second high priority will be indicated. When an error occurs and then is cancelled in the middle of printing, the printer will resume printing on the ongoing page. Message area: Port Busy Error message area: The port is being used by another device. [. . . ]