Abstract: A method and apparatus are provided to calibrate a xerographic print engine toner concentration sensor to accurately control the toner concentration to a specified operating target. At least two control patches are imaged onto a photoreceptor. Each patch has a different voltage level where the voltage levels are the difference between the exposure discharge voltage and the developmental roll voltage. The relative reflectivity of each patches is obtained. The latent patches are repeatedly developed at different toner concentrations. The reflectivities of the patches formed at the same toner concentration are combined to obtain a combined reflectivity for that toner concentration. As a result, a toner concentration curve is obtained that has an improved response relative to the toner concentration curves that correspond to each of the individual voltage levels.

Abstract: A system and method suppresses automatically a background of a document being scanned. A histogram circuit generates a histogram from a predetermined group of scanlines of image data collected at a lead edge of the document being scanned, and a gain correction circuit calculates a gain value from the histogram and applies the gain to the image data. The histogram circuit generates a next histogram from a next predetermined group of scanlines of image data collected from the document being scanned. The gain correction circuit then calculates a next gain value from the next histogram. A comparator enables the application of the next gain value to the image data if the next gain value is less than a previously calculated gain value.

Abstract: A printing machine having a moving imaging surface, a projecting system for modulating a beam and projecting an image onto the imaging surface, a developer for application of toner to the image projected onto the imaging surface for transfer of the image to a medium, a method of development control including the steps of; generating a setup calibration tone curve base on a preset representative halftone patches; marking a test pattern in the interdocument zone of the imaging surface, the test pattern comprising a plurality of halftone patches; sensing the test pattern and measuring a relative reflection of each of said plurality of halftone patches in the interdocument zone of the imaging surface; entering said measured values into a matrix and correlating said matrix to a plurality of print quality actuators; generating a representative tone reproduction curve base on the matrix results; producing a feedback signal by comparing the representative tone reproduction curve to said setup calibration tone curve;

Abstract: A method adjusting variations in toner concentration in a printing machine by first determining a pixel count of documents to be imaged. The system then provides two test targets on the imaging surface in the image area, one of the test targets having a relatively low reflectance and the other test target having a medium reflectance. The reflectance value of the test targets is sensed and the difference between the reflectance values is calculated and compared to a reference value to provide an error value. The system then to the error value and the pixel count of documents to be imaged to determine a time period of dispense for a toner dispenser.