Abstract:
The present invention employs an inexpensive method and apparatus for media height sensing. A sheet fed media-using-machine (63) has a media holder (64). The media holder (64) holds a stack (24) of a variable quantity of sheets of a medium to be supplied to a media-using-machine (63). The media holder (64) has a structure (30) for supporting the sheets and has a stack pusher (32) which may be a mechanical device that pushes the stack into a position such that said media-using-machine (63) may withdaw the sheets from said stack (24). The stack pusher (32) has a variable position within a range of motion wherein such position is dependent upon a quantity of sheets in the stack (24). A variable device (40) is attached to the stack pusher such that an electrical property of said variable device varies in relation to said position thereby allowing calculation of an estimate of the quantity of sheets in said stack (24), where the calculation is performed using said electrical property. The variable device (40) may be, for example, a capacitor or a resistor, and the electrical property being capacitance or resistance, respectively.
Abstract:
An apparatus and a method for optimizing the quality of electrophotographic imaging based on the properties of the printing media are presented. In order to determine the properties of the printing media without interrupting the normal image transfer process, the present invention uses rollers (36) as a part of a sensor. When the printing media lies between the rollers (36), the rollers and the printing media form an RC circuit. A pulse is applied to the RC circuit, the step response of which is periodically sampled. The samples may be obtained logarithmically in time. Based on the resultant response, a controller (30) calculates the resistance (R m ) and the capacitance (C m ) of the printing media and adjusts imaging parameters, such as the transfer bias voltage, for optimal image transfer. The entire optimization process occurs between the time of the printing media passes through the rollers (36) and the time the imaging transfer is executed.