Patent ID: 7872662

Claim:
A printer, comprising: a lower unit including a paper storage for storing paper; an upper unit adapted to open and close pivotably relative to the lower unit; a paper path which is formed between the lower unit and the upper unit and extends from the paper storage to an exterior; a printing section for executing a print operation on the paper; a sensor unit which: (i) comprises a lower sensor holder which includes one of a light emitting element and a light receiving element, and an upper sensor holder which includes the other of the light emitting element and the light receiving element, and (ii) is attached to the lower unit such that the paper path passes between the lower sensor holder and the upper sensor holder, wherein the upper sensor holder is openable and closeable by pivoting about a fulcrum positioned at a first end of the upper sensor holder in a width direction of the paper path, and a second end of the upper sensor holder is a free end; a support mechanism for supporting the upper sensor holder when the upper sensor holder has been opened; and a displacing mechanism including a displacing member which is moved in accordance with a closing motion of the upper unit, and which, upon movement thereof in accordance with the closing of the upper unit, exerts a force on the upper sensor holder, which is supported by the support mechanism, in a direction to cause the upper sensor holder to pivot and close by its own weight; wherein when the upper sensor is supported by the supporting mechanism, the upper sensor holder is positioned at an obtuse angle relative to the lower sensor holder, and wherein the displacing member comprises a slider which is driven by the closing and opening of the upper unit to slide in a direction in which a pivot shaft of the upper sensor holder extends, and the slider moves along a movement path which interferes with the upper sensor holder when the upper sensor holder is supported by the support mechanism and which does not interfere with the upper sensor holder when the upper sensor holder is closed, such that the force is exerted on the upper sensor holder by the slider when the slider interferes with the upper sensor holder, so as to cause the upper sensor holder to be closed pivotably by its own weight.