Clamp

1. A unit mask clamp that clamps an end of a unit mask that is supported while a tensile force is applied to the unit mask, the clamp comprising:

a clamp main body; and

a rotation contact portion rotatably supported by the clamp main body and directly contacting the end of the unit mask,

the rotation contact portion including a concaved portion and the clamp main body including a non-rotatable shaft inserted to the concaved portion, the rotation contact portion rotating about the non-rotatable shaft.

2. The clamp of claim 1 , wherein the clamp main body is directly connected to the non-rotatable shaft inserted to the concaved portion.

3. The clamp of claim 1 , further comprising bearings provided between the concaved portion and the non-rotatable shaft and surrounding the non-rotatable shaft.

4. The clamp of claim 1 , wherein an elastic restoring force is generated between the rotation contact portion and the clamp main body.

5. The clamp of claim 4 , further comprising a restoring spring directly connecting the rotation contact portion and the clamp main body and generating the elastic restoring force.

6. The clamp of claim 1 , further comprising a stopper that is provided between the rotation contact portion and the clamp main body and that limits rotation of the rotation contact portion, the stopper being movable into the clamp main body from between the rotation contact portion and the clamp main body when the rotation contact portion contacts the end of the unit mask.

7. The clamp of claim 1 , wherein:

the rotation contact portion includes:

a first sub-rotation contact portion contacting a bottom side of the end of the unit mask and

a second sub-rotation contact portion contacting a front side of the end of the unit mask, and

the clamp main body includes,

first tongs disposed on the bottom side of the end of the unit mask, the first tongs including a concaved first groove where the first sub-rotation contact portion is located, the first tongs being directly connected to the non-rotatable shaft, and

second tongs disposed on the front side of the end of the unit mask so as to be rotatable to a direction of the first tongs, the second tongs including a concaved second groove where the second sub-rotation contact portion is located, the second tongs being directly connected to the non-rotatable shaft.

8. The clamp of claim 7 , further comprising:

a first stopper disposed between the first sub-rotation contact portion and the first tongs to limit rotation of the first sub-rotation contact portion, the first stopper being movable into the first tongs from between the first sub-rotation contact portion and the first tongs when the first sub-rotation contact portion contacts the end of the unit mask; and

a second stopper disposed between the second sub-rotation contact portion and the second tongs to limit rotation of the second sub-rotation contact portion, the second stopper being movable into the second tongs from between the second sub-rotation contact portion and the second tongs when the second sub-rotation contact contacts the end of the unit mask.

9. The clamp of claim 8 , wherein:

the first tongs further include a first protruded side disposed on an imaginary line that aligns with a first contact side of the first sub-rotation contact portion that is in contact with the end of the unit mask,

the second tongs further includes a second protruded side disposed on an imaginary line that aligns with a second contact side of the second sub-rotation contact portion that is in contact with the end of the unit mask,

the first stopper includes:

a first stopper main body extended in a bent manner into the first tongs from between the first sub-rotation contact portion and the first tongs, the first stopper main body penetrating the first protruded side, and

a first spring located in the first tongs and generating an elastic restoring force between the first stopper main body and the first tongs, and

the second stopper includes:

a second stopper main body extended in a bent manner into the second tongs from between the second sub-rotation contact portion and the second tongs and penetrating the second protruded side, and

a second spring disposed in the second tongs and generating an elastic restoring force between the second stopper main body and the second tongs.

10. The clamp of claim 8 , wherein:

the first stopper includes:

a third main body extended into the first tongs from between the first sub-rotation contact portion and the first tongs and then protruded in a bent manner to the outside of the first tongs, and

a third spring disposed in the first tongs and generating an elastic restoring force between the third stopper main body and the first tongs,

the second stopper includes:

a fourth stopper main body extended into the second tongs from between the second sub-rotation contact portion and the second tongs and then protruded in a bent manner to the outside of the second tongs, and being overlapped with the third stopper main body, and

a fourth spring disposed in the second tongs and generating an elastic restoring force between the fourth stopper main body and the second tongs,

the first tongs further include a protrusion protruded in a direction of the second tongs, and

the second tongs further include a weight being liftable by the protrusion, a lever shaft extended from the weight and supported by the second tongs, and a lever bar including a hook extended to the fourth stopper from the lever shaft.