Patent ID: 7854427

Claim:
A paper feed tray unit for a printer with a controller, comprising: a paper support for supporting paper supplied to a paper inlet for feeding at least one printing paper into the printer in a paper feed direction and for receiving the at least one printing paper thereon; a pair of slide guides provided on the paper support so as to be movable in a width direction which is perpendicular to the paper feed direction; a drive mechanism which is provided with a drive motor for moving the slide guides closer to or away from each other in opposite directions, and which is controlled by the controller to automatically move the slide guides to a predetermined position according to a paper size input to the controller by a user; a paper sensor for detecting whether or not a printing paper is present on the paper support; and a guide position sensor provided on at least one of the slide guides for detecting the position of the slide guides based on markings on a paper width detection sheet provided on a housing of the printer in the vicinity of the paper inlet at a location facing the guide position sensor and corresponding to a moving range of the guide position sensor, wherein: the controller determines, using the paper sensor, whether a printing paper is present on the paper support; the controller recognizes the position of the slide guides based on an output level of a detection signal, which is output from the guide position sensor by detecting the markings on the paper width detection sheet, if the controller determines that an absence of a printing paper on the paper support exists; the controller controls the drive mechanism to move the slide guides according to the paper size input by the user for printing; and the controller stops the drive mechanism when the output level of the detection signal is equal to a level corresponding to the input paper size, while the controller allows the slide guides to stay still if the controller determines, using the paper sensor, that a printing paper is present on the paper support.