Patent ID: 8495821

Claim:
A sheet stack thickness estimating device for detecting a thickness of a stack of sheets on a paper tray, comprising: a driving device, for providing a motive force to the sheet stack thickness estimating device; a first connecting rod, comprising a notch, wherein the first connecting rod connects to the driving device, so as to be driven to move horizontally by the driving device; a second connecting rod, wherein a first end of the second connecting rod connects to the first connecting rod and is synchronized with the first connecting rod, and a second end of the second connecting rod is pivoted to a shaft and is capable of rotating about the shaft; a pressing part, for pressing the stack of sheets on the paper tray, wherein the pressing part is extended from the second end of the second connecting rod; and a sensor, comprising an emitting end and a receiving end, wherein the emitting end and the receiving end are respectively located at two side of the first connecting rod.