Patent ID: 7654518

Claim:
An image forming apparatus, comprising: a paper cassette, in which a printing medium is loaded; and a guide unit which registers the printing medium loaded in the paper cassette, according to a size of the printing medium, wherein the guide unit comprises: a length-adjusting assembly to register the printing medium lengthwise, comprising a length-adjusting rack part; a width-adjusting assembly to register the printing medium widthwise, comprising a width-adjusting rack part; and a pinion assembly having a stepped shape to interlock the length-adjusting assembly and the width-adjusting assembly, comprising a first pinion part to engage with the length-adjusting rack part, and a second pinion part to engage with the width-adjusting rack part, wherein the length-adjusting rack part comprises a first rack gear to engage with a first side of the first pinion part, and a second rack gear to engage with a second side of the first pinion part.