Means and method for controlling raster output scanner intensity

Claim 1

In a raster output scanner a combination of a laser source for generating modulated high intensity output beams of radiation in response to input video image signals, means to scan said beams across a photoreceptor to expose said photoreceptor forming a latent electrostatic image thereon, means for developing said exposed latent image and transferring said developed image to an output medium, the combination of, a memory means for storing data relating to a plurality of beam intensity correction signals, each stored signal creating a different varying beam intensity exposure of the photoreceptor, and means for periodically providing test pattern video signals to said laser source causing a test pattern output print to be formed, said test pattern output print formed with a plurality of horizontal bands of differing density, each band produced by a scanning beam having a beam intensity which varies across scan in conformance with an associated one of said beam correction signals, and wherein one of said bands has a generally uniform density further including means for changing the beam intensity level of said laser output in response to changes in the test pattern band representing optimum density.

Claim 4

A method for correcting for variations in scanning intensity levels in a ROS printer comprising the steps of, creating and storing in memory input data signals representing a test pattern of varying density segments, creating and storing in memory a series of beam intensity correction signals, each said correction signal associated with one of said test pattern density segments, and periodically inputting to a laser source, said test pattern input data, scanning the laser output across a photoreceptor surface to produce a latent image of pattern density segments developing said latent image and transferring the image to an output sheet comprising a test pattern print having a plurality of horizontal bands of differing density, visually observing said bands and identifying a band of optimum uniform density, selecting the beam intensity correction signal associated with said identified band, and applying said correction signal to said laser.

Claim 5

A method for correcting for variations in scanning intensity levels in a ROS printer comprising the steps of, creating and storing in memory input data signals representing a test pattern of varying density segments, creating and storing in memory a series of beam intensity correction signals, each said correction signal associated with one of said test pattern density segments, and periodically inputting to a laser source, said test pattern input data, scanning the laser output across a photoreceptor surface to produce a latent image of pattern density segments developing said latent image and transferring the image to an output sheet comprising a test pattern print having a plurality of horizontal bands of differing density, visually observing said bands and identifying a band of optimum uniform density, selecting the beam intensity correction signal associated with said identified band, and applying said correction signal to said laser.