Nipped rollers for centering images on sheet media

A method for sensing the position of an electrical resistive sheet media moving along a transport path having a center line in a processing device, the method includes the steps of:

• a) positioning a pair of parallel nipped rollers laterally across a transport path for said sheet media, said nipped rollers being formed from an electrical conductive material and arranged to have a lineal contact area between said rollers;
• b) dividing one of said rollers at its mid-point to form two electrically insulated halves and aligning the mid-point of said divided roller with the mid-point of said transport path;
• c) connecting an electrical power source to the undivided roller and connecting an electrical output from each of said insulated halves;
• d) passing an electrically resistive sheet media between said rollers which will reduce the length of the lineal contact area between each of the halves of the divided roller and the undivided roller;
• e) measuring the electrical current from each half of the divided roller and determining the length of the remaining lineal contact area for each half which determines the actual position of the sheet media with respect to the center line of the transport path;
• and
• f) generating an output signal which is indicative of the position of the sheet media at the time that the reading is taken.

An image aligning system for an image printing device wherein the image is aligned with a sheet media in a transport path which includes a center line whereby the image will be properly registered and printed on the sheet media during a printing operation, said sheet media having a relatively high electrical resistivity, the system comprising;

• a) an image printing device in communication with a sheet media transport path, said printing device having a processing means capable of positioning and adjusting the image to be printed;
• b) a pair of nipped parallel rollers arranged laterally opposed to the transport path so that the sheet media will pass between said rollers as it moves along said transport path to said printing device;
• c) said pair of nipped rollers includes a first roller having an electrically conductive outer surface and a second roller having an electrically conductive outer surface which is separated circumferentially at its mid-point to form two insulated electrically conductive surface halves, the mid-point of said second roller being aligned with the center line of the transport path;
• d) said first and second rollers being arranged to have a lineal contact area formed therebetween;
• e) the surface of said first roller being connected to an input electrical source, each of said surface halves of said second roller having an electrical output which is related to the current flowing through the lineal contact area between the first roller and each of the halves of the second roller;
• f) an output processor means for determining the resulting lineal contact dimensions for each half as an electrical resistive sheet passes between said rollers, said output processor generating an image position correction signal for the print processor which is indicative of the actual lateral position of the sheet media with respect to the center line of the transport path at the time that the signal is generated so that the print processor can align the image so that it will be properly registered with the sheet media as it passes through the printing operation.