Abstract: A method by which the target of a toner concentration (TC) sensor can be set up based on the equivalent developability concept without using an expensive patch generator. First, use a black toner area coverage (BTAC) sensor to measure the relative reflectance (RR) of a 100% area coverage developed patch (ROS generated) at a series of development levels (Vem or Vdev) to generate a pseudo development curve and estimate VdO in real-time (VdO is the Vdev level that starts to develop toner onto the photoreceptor belt.) Then, add a nominal delta Vdev to VdO to get the development level (Vdev) needed to generate 100% area coverage gray patch. Finally, using a BTAC sensor to measure the RR level of a 100% area coverage (AC) gray patch, move the target of the TC sensor, and converge the sensor's reading to the sensor's target continuously until the RR level of the gray patch hits the RR target (predefined) within the tolerance range. Thus, the target of the TC sensor is set for the xerographic system automatically.

Abstract: A method of using toner concentration (TC) as an active actuator in the tonal reproduction curve (TRC) controller, so that not only will the TRC controller maintain the TRC of the output, but also all the electrostatic actuators will not diverge, and the toner concentration will be within the latitude range of the xerographic system. The process ensures that the target of the toner concentration (TC) sensor will be changed properly in direction (up/down) and amplitude to compensate the TRC output of the print engine based on either reflective reactance readings and/or the level of the electrostatic actuators.

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 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 corotron assembly comprising a coronode for generating an electrostatic field and including an electrically nonconductive protective guard having a U-shaped base member forming a channel for receiving the coronode wherein a plurality of finger elements are provided, extending from the sidewalls such that the coronode is recessed between the finger elements. Each finger element is further provided with a spherical radii tip for reducing the attenuating effects of the finger elements on the electrostatic field generated by the coronode.