Patent ID: 8449065
Filing Date: 2013-05-28
Classification: B41J

Abstract:
1. An image forming apparatus that forms an image by discharging a liquid on a medium, the image forming apparatus comprising: a discharge head that discharges a liquid; a movement unit that reciprocates the discharge head such that the discharge head moves across the medium placed on a placement surface; a light emitting/receiving unit that is mounted on the movement unit so as to be capable of moving, and that includes a light emitting section for emitting light in a substantially vertical direction to the placement surface and a light receiving section for receiving reflected light from the substantially vertical direction to the corresponding placement surface; a reflection member that is formed on a non-placement surface which is different from the placement surface, and that, when the light emitting/receiving unit is moved into a position which faces the non-placement surface by the movement unit, reflects light emitted from the light emitting section in a substantially parallel direction to the placement surface, and that reflects the light from the substantially parallel direction to the placement surface in a substantially vertical direction to the corresponding placement surface; a position detection unit that detects a position in a movement direction of the light emitting/receiving unit; and a medium size determination unit that performs operations of: (a) determining a width of the medium based on a light reception signal detected by the light emitting/receiving unit and a position signal detected by the position detection unit while moving the light emitting/receiving unit such that the light emitting/receiving unit moves across the medium placed on the placement surface; and (b) determining a thickness of the medium based on the light reception signal detected by the light emitting/receiving unit and the position signal detected by the position detection unit while moving the light emitting/receiving unit such that the light emitting/receiving unit moves across the reflection member.