Patent ID: 7370862

Claim:
An apparatus for detecting overlay of paper, comprising: paper feeding means for guiding upper and lower surfaces of the paper and feeding the paper; a pivot member pivotally installed to a rotary shaft, and having a contact portion disposed in a paper feeding path of the paper feeding means and contacting with one surface of the feeding paper, and an encoder portion with a plurality of slits, in which the rotary shaft is closer to the contact portion rather than the encoder portion; and a sensor for counting the number of slits of the encoder portion when the pivot member pivots, wherein the paper feeding means includes: paper guides including an upper paper guide formed with a through-hole and a lower paper guide spaced apart from each other at a constant interval to form the paper feeding path between the two guides; and two conveyor belts installed to a belt mounting groove formed along a paper feeding direction for forcibly contacting the upper and lower surfaces of the paper and feeding the paper, wherein the upper paper guide includes a protruding fixture which protrudes upward from one side of the through-hole, wherein the pivot member is pivotally coupled to the rotary shaft formed at a lower part of the protruding fixture, wherein the pivot member includes a torsion spring for urging the contact portion against the paper, wherein the sensor includes a photo sensor including a light emitting portion and a light receiving portion which are disposed opposite to front and rear surfaces of the plurality of slits of the encoder portion and installed to an upper part of the protruding fixture, wherein the contact portion penetrates though the through-hole and includes a roller.