Apparatus and method for measuring recording medium thickness, apparatus and method for detecting multi-feed of recording medium and apparatus and method for forming image

Abstract

A recording medium thickness measuring apparatus includes: an output value detection unit that detects an output value which fluctuates in accordance with thickness of a recording medium passing through a predetermined position of a transport path; and a calculation unit that calculates the thickness of the recording medium based on a first output value detected by the output value detection unit before passage of the recording medium and after passage of an immediately preceding recording medium in the predetermined position of the transport path, and a second output value detected by the output value detection unit while the recording medium is passing through the predetermined position.

Description

Technical field [0001] The present invention relates to an apparatus and method for measuring the thickness of a conveyed recording medium, an apparatus and method for detecting multi-page conveyance of a recording medium, and an apparatus and method for forming an image. Background technique [0002] As is well known, an image forming apparatus such as a printer, a facsimile machine, or a multi-function device detects the overlapping state of multiple sheets of paper (multi-page conveyance). [0003] Japanese Published Unexamined Patent Application No. Heisei 3-192050 discloses such a paper multi-page conveyance detection device by measuring the difference between the thickness data of the nth page and the data in the absence of paper. The difference between the thickness data of the (n+1)th sheet of paper and the data in the absence of paper is compared to determine the occurrence / non-occurrence of multi-page conveyance. [0004] Japanese Published Unexamined Patent Application...

AI Technical Summary

Problems solved by technology

[0006] However, since the data update in the absence of paper and the multifeed judgment criterion values ​​are calculated based on the data in the case of paper present, these values ​​are affected by variations in the respective paper thickness values, and the accuracy of judgment is lowered

Also, when the interval between paper conveying operations is long, the sensor output value changes greatly after detection of the previous paper presence position data

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