Medium support tray, medium conveyance device, and recording device

A medium support tray comprising:

• a support part configured to support a medium to be conveyed;
• an auxiliary support part provided expandably with respect to the support part, the auxiliary support part being configured to support the medium together with the support part at an expanded position upstream of the support part in a conveyance direction of the medium;
• a side end guide part provided at the support part movably in a width direction intersecting the conveyance direction, the side end guide part being configured to regulate a side end in the width direction of the medium supported by the support part;
• an auxiliary side end guide part provided at the auxiliary support part movably in the width direction, the auxiliary side end guide part being configured to regulate the side end of the medium supported by the auxiliary support part;
• and
• a coupler coupling the side end guide part and the auxiliary side end guide part,
• wherein the side end guide part moves in the width direction in conjunction with movement of the auxiliary side end guide part in the width direction and expandably guides the auxiliary support part via the coupler,
• wherein the coupler includes
• a guiding part provided at the auxiliary side end guide part, the guiding part extending along the conveyance direction, and
• a lever provided at the side end guide part and fitted to the guiding part, and
• the auxiliary support part is expanded with respect to the support part by the guiding part sliding with respect to the lever.