Droplet ejecting apparatus having carriage marks, droplet ejecting method, and computer storage medium

1. A droplet ejecting apparatus comprising:

a workpiece table configured to receive a workpiece;

a carriage including a plurality of pairs of droplet ejecting heads which includes a first pair of droplet ejecting heads provided side by side to a second pair of droplet electing heads in a main scanning direction, the main scanning direction being orthogonal to a sub-scanning direction, and a plurality of carriage marks which includes a first carriage mark and a second carriage mark, said first carriage mark and said second carriage mark being disposed on a lower surface of the carriage at opposite ends of the carriage and arranged along a centerline of the carriage in the main scanning direction, each droplet ejecting head including a nozzle surface configured to eject droplets of a functional liquid onto the workpiece placed on the workpiece table so as to draw a pattern;

a workpiece mover configured to move the workpiece table in the main scanning direction relative to the carriage;

a position detector including a camera configured to detect a position of the first pair of droplet ejecting heads by capturing an image of the first carriage mark and the second carriage mark of the first pair of droplet ejecting heads;

a scanning direction slider configured to move the camera relative to the carriage in the main scanning direction; and

a controller configured to:

perform a first movement of the camera in the main scanning direction using the scanning direction slider to a first image capturing position directly under the first carriage mark to detect a position of the first carriage mark;

perform a second movement of the camera in the main scanning direction using the scanning direction slider to a second image capturing position directly under the second carriage mark to detect a position of the second carriage mark;

calculate positional deviation amounts in the main scanning direction between the position of the first carriage mark detected by the camera in the first movement and a reference position of the first carriage mark, and between the position of the second carriage mark detected by the camera in the second movement of the camera and a reference position of the second carriage mark; and

correct a droplet ejection timing of the plurality of droplet ejecting heads based on the positional deviation amounts,

wherein the plurality of pairs of the droplet ejecting heads are arranged such that nozzle surfaces of each pair of the plurality of pairs of droplet ejecting heads are symmetrically arranged on opposite sides of the centerline of the carriage.

2. The droplet ejecting apparatus of claim 1 , further comprising:

a droplet ejecting head mover configured to move the droplet ejecting heads in a rotation direction and a sub-scanning direction orthogonal to the main scanning direction,

wherein the plurality of carriage marks are positioned side by side in the main scanning direction to correspond to the position of the droplet ejecting head.

3. The droplet ejecting apparatus of claim 2 , wherein the controller is further configured to:

calculate the positional deviation amounts in the sub-scanning direction and the rotation direction between the position of the first carriage mark detected by the position detector and the reference position of the first carriage mark and between the position of the second carriage mark detected by the position detector and the reference position of the second carriage mark; and

correct positions of the plurality of pairs of droplet ejecting heads in the sub-scanning direction and the rotation direction based on the positional deviation amounts in the sub-scanning direction and the rotation direction.

4. The droplet ejecting apparatus of claim 1 , further comprising:

a flusher and an ejection inspector configured to perform maintenance of the plurality of pairs droplet ejecting heads,

wherein the scanning direction slider is configured to move the flusher and the ejection inspector relative to the plurality of pairs droplet ejecting heads in the main scanning direction, and

the position detector is provided on the scanning direction slider.

5. The droplet ejecting apparatus of claim 1 , wherein a plurality of position detectors are provided at positions corresponding to the plurality of pairs of droplet ejecting heads.

6. The droplet ejecting apparatus of claim 1 , wherein the position detector is configured to be movable in the sub-scanning direction.

7. A droplet ejecting method comprising:

providing a workpiece table configured to receive a workpiece;

providing a carriage including a plurality of pairs of droplet ejecting heads which includes a first pair of droplet ejecting heads provided side by side to a second pair of droplet ejecting heads in a main scanning direction, the main scanning direction being orthogonal to a sub-scanning direction, and a plurality of carriage marks which includes a first carriage mark and a second carriage mark, the first carriage mark and the second carriage mark being disposed on a lower surface of the carriage at opposite ends of the carriage and arranged along a centerline of the carriage in the main scanning direction, each droplet ejecting head including a nozzle surface configured to eject droplets of a functional liquid onto the workpiece placed on the workpiece table so as to draw a pattern;

providing a workpiece mover configured to move the workpiece table in the main scanning direction relative to the carriage;

detecting, with a position detector including a camera a position of the first pair of droplet ejecting heads by capturing an image of the first carriage mark and an image of the second carriage mark of the first pair of droplet ejecting heads;

providing a scanning direction slider configured to move the camera relative to the carriage in the main scanning direction;

providing a controller configured to: calculate a positional deviation amount in the main scanning direction between the position of the first pair of droplet ejecting heads detected by the position detector and a reference position of the first pair of droplet ejecting heads and correct a droplet ejection timing of the first pair of droplet ejecting heads based on the positional deviation amount;

performing a first movement of the camera in the main scanning direction using the scanning direction slider to a first image capture position under the first carriage mark to detect a position of the first carriage mark;

performing a second movement of the camera in the main scanning direction using the scanning direction slider to a second image capturing position directly under the second carriage mark to detect a position of the second carriage mark;

calculating with the controller positional deviation amounts in the main scanning direction between the position of the first carriage mark detected by the camera in the first moving and a reference position of the first carriage mark, and between the position of the second carriage mark detected by the camera in the second moving and a reference position of the second carriage mark; and

correcting with the controller the droplet ejection timing of the first pair of droplet ejecting heads based on the positional deviation amounts,

wherein the plurality of pairs of the droplet ejecting heads are arranged such that nozzle surfaces of each pair of the plurality of pairs of droplet ejecting heads are symmetrically arranged on opposite sides of the centerline of the carriage.

8. The droplet ejecting method of claim 7 , wherein the calculating step includes:

calculating positional deviation amounts in a sub-scanning direction orthogonal to the main scanning direction and positional deviation amounts in a rotation direction between the position of the first carriage mark and the reference position of the first carriage mark, and the positional deviation amounts in the sub-scanning direction and the positional deviation amounts in the rotation direction between the position of the second carriage mark and the reference position of the second carriage mark; and

correcting positions of the plurality of pairs of droplet ejecting heads in the sub-scanning direction and the rotation direction based on the positional deviation amounts in the sub-scanning direction and the positional deviation amounts in the rotation direction.

9. The droplet ejecting method of claim 7 , further comprising:

performing the calculating step before the droplets are ejected onto the workpiece and performing maintenance of the plurality of pairs of droplet ejecting heads using a flusher and an ejection inspector, and

providing the position detector on a scanning direction slider, the scanning direction slider being configured to move the flusher and the ejection inspector relative to the carriage in the main scanning direction.

10. The droplet ejecting method of claim 7 , further comprising: providing a plurality of position detectors in the sub-scanning direction, and

in the detecting step, detecting with the plurality of position detectors positions of the plurality of pairs of droplet ejecting heads which correspond to the plurality of position detectors, respectively.

11. The droplet ejecting method of claim 7 , wherein in the detecting step detecting with the position detector positions of the plurality of pairs of droplet ejecting heads while moving the position detector in the sub-scanning direction.