File information: | |
File name: | Process Control.pdf [preview ] |
Size: | 1448 kB |
Extension: | |
Mfg: | |
Model: | |
Original: | |
Descr: | Process Control |
Group: | Electronics > Other |
Uploaded: | 20-10-2009 |
User: | ghost2003 |
Multipart: | No multipart |
Information about the files in archive: | ||
Decompress result: | OK | |
Extracted files: | 1 | |
File name Process Control.pdf Process Control Basic Concepts Process control is a system that automatically changes machine processes to compensate for changes in the environment or the machine condition. The objective of process control is to stabilize the quality of image output. The practical result is a decrease in the frequency of service calls, thus increasing customer satisfaction and decreasing service cost. The box to the right lists the machine conditions that process control compensates for. Basic Concepts OPC Analog Systems OPC Digital Systems Selenium Analog Systems Target Machine Conditions ! Dirty optics ! Exposure lamp deterioration ! Dirty charge corona wire/grid ! Change of drum sensitivity ! Deterioration of developer In this section (Basic Concepts) we will take an overall look at process control. Then we will look at the details of process control using several example machines. We will look at two OPC analog machines--one using a potential sensor (model A095) and one using a V sensor (model A074). Then we will study an OPC digital system (model A229). Finally, we will look at selenium drum analog systems (models A029 and A058). NOTE: Unlike other parts of the Core Technology Manual, we don't pull out and compare example sub-units of process control but instead look at the process control systems of the example machines in their entirety. This is because process control components are interactive and best studied as a whole. 1 April 2001 Page 848 PROCESS CONTROL Basic Concepts Latent Image Control and Image Density Control This illustration represents a copier model that uses two process control methods. One compensates for variation in the drum potential (latent image control) and the other controls the toner concentration and toner supply amount (image density control). All process control components affect one or the other (or both) of these methods. 1 April 2001 Page 849 PROCESS CONTROL Basic Concepts Latent Image Control The figure shows the changes of the drum potential during the copy process. VO VD (Dark Potential) VL (Light Potential) VR (Residual Voltage) Drum potential just after charging the drum. Drum potential just after exposing the black pattern (VD pattern) Drum potential just after exposing the white pattern (VL pattern) Drum potential just after the exposure of the erase lamp. 1 April 2001 Page 850 PROCESS CONTROL Basic Concepts Image Density Control The following sensors control image density. · · Toner density sensor (TD sensor) Image density sensor (ID sensor) Data from the TD sensor is used to keep the toner concentration in the developer at a constant level. However, the image on the OPC drum varies due to the variation of toner chargeability (influenced by the environment) even if the toner concentration is constant. By the ID sensor compensation, toner concentration is changed to keep the image density on the OPC drum constant. The following items are controlled to maintain a constant copy image density: · · To |
Date | User | Rating | Comment |