Patent ID: 7911652

Claim:
A method comprising: (a) writing a first periodic spatial test pattern in a non-image area of a photoreceptor while simultaneously writing a first image in an image area of the photoreceptor; (b) sensing the first pattern at the photoreceptor; (c) computing first amplitude and phase values using a stored first banding frequency value and measurements of the sensed first pattern; (d) comparing the first amplitude and phase values to a threshold; (e) if the threshold is not met, instituting writing a second, different periodic spatial test pattern in a non-image area of the photoreceptor while simultaneously writing a second image in the image area of the photoreceptor; (f) sensing the second test pattern at the photoreceptor; (g) computing a current second banding frequency value from the measurements of the sensed second test pattern; (h) updating the memory to replace the stored first banding frequency value with the current second banding frequency value; and, (i) repeating steps (a) through (d).