Printing apparatus

1. A printing apparatus comprising:

a transport roller configured to transport a print medium in a transport direction;

a print head configured to print on the print medium;

a platen having first suction arrays each including at least a first suction hole having a first diameter and second suction arrays each including at least a second suction hole having a second diameter that is different from the first diameter, the first suction arrays and the second suction arrays being alternately arranged in a direction intersecting the transport direction;

a suction fan configured to suck the print medium through frame portions each having one first suction array and one second suction array; and

a shutter mechanism configured to open or close the frame portions stepwise.

2. The printing apparatus according to claim 1 , wherein the first diameter is larger than the second diameter.

3. The printing apparatus according to claim 2 , wherein the platen has a reference position along which an end of the print medium in a width direction passes through, and

each of the frame portions includes the second suction array and the first suction array that is closer to the reference position than the second suction array.

4. The printing apparatus according to claim 1 , wherein the shutter mechanism comprises a drum having first openings corresponding to the frame portions and second openings of sizes different from the sizes of the first openings, the first openings and the second openings being arranged in the direction intersecting the transport direction, and a drum drive unit configured to drive the drum to rotate.

5. The printing apparatus according to claim 4 , wherein the shutter mechanism comprises an air intake chamber that communicates with the frame portions and the suction fan, and

the drum is rotated in the air intake chamber to open or close stepwise the frame portions.