Panasonic FP-7818, Service Manual & Parts Manual

Page: 26 / 402

Control
Functions
2-1
Section II
Control Functions
2. 1 Image Control
Qualitative Reasoning Based Adaptive Controller
• Even if the toner density is at it's standard level, the copy image may vary with time
depending on the characteristics of drum and the environmental variations.
To prevent this change, the copy density sensor which is installed under the
developer unit controls the image to stablize the copy image.
• Controlling the image
During initialization after turning on the power, the copy density sensor reads the
white density, medium density (line pattern density patch) and black density
developed on the drum surface.These three values are compared with the ideal
gamma curve stored in the copiers memory.
The copier detects the amount offset from the standard gamma curve (such as "a
little background" or "light image") and calculates the variables for copy density
control in accordance with Qualitative Reasoning Based Adaptive Controller. In
this way it finds the optimum compensation values to tighten the gamma curve for
maintaining peak copy quality.
By means of this process, copy quality is stabilized by the various compensations
enabled by Qualitative Reasoning Based Adaptive Controller adjustment in image
production.
• The control of the gamma curve stabilizes copy quality by monitoring three points
of copy quality (white density, medium density and black density) and has a direct
effect on background, solid area density and good reproduction of fine lines
regardless of environmental changes and variation with time and copy volume.