1. Field of the Disclosure
The present disclosure relates document creation. More specifically, the present disclosure is directed to a system and method for actively detecting the depth of penetration of a decurling roller
2. Brief Discussion of Related Art
In a printer, substrate media, e.g., paper, vellum, etc., is often turned over rollers or drums, etc., for example to change direction of media transport in handling and/or to effect printing processes. Occasionally and to varying degrees, the media retains the shape of the bend, which is referred to as “curl”. Curl is often detrimental to further handling and processes, and is undesirable in the finished document.
To address the problem of curl, U.S. Pat. No. 6,282,403 to Spencer, et al. (“Spencer”), hereby incorporated by reference, discloses a Decurler Roll Setup. The solution embodied in Spencer, e.g., is to pass the media over a decurling roller that has a radius in the opposite direction of the curl, to reverse the curl and result in a flatter media. For example, it is known from Spencer to use a pinch roller in conjunction with an opposing elastomeric roller, with the pinch roller penetrating the elastomeric roller and the media passing between the two rollers (Spencer, FIG. 2B). Accordingly, the elastomeric roller presses the media (sheet “S”) over the pinch roller. Furthermore, in such an embodiment, the pinch roller has substantially smaller radius, as compared with both the radius of the curl exhibited in the media, and the opposing elastomeric roller.
In a decurling technique and apparatus as just disclosed by Spencer, the amount by which the media is to be decurled is variable, and is dependent upon the depth of penetration of the pinch roller into the elastomeric roller. Accordingly, the relative position of the two rollers must be controlled to a high degree of precision and accuracy. Accurately determining the relative position of the pinch and elastomeric decurling rollers in Spencer requires a relatively lengthy homing process (Spencer, FIG. 7), which slows cycle time and is a significant source of customer dissatisfaction.
Further, the process only infers the positions of the rollers by calculation. In order to calculate the position accurately, extremely tight tolerances in the mechanism are required, which increases build costs.
Lastly, one common and cost-effective method of locating the rollers is by use of a cam driven by a step motor. However, the failure to hold position of the cam under load is another source of error in decurling operation. Spencer does not provide real-time feedback of the relative positions between the pinch roller and the elastomeric roller. Therefore, an inadvertent shift of position by the step-motor driven locating system cannot be detected.