Image recording apparatus and image recording method

1. An image recording apparatus that irradiates a recording target with laser light and records an image thereon, the image recording apparatus comprising:

a laser irradiation device that has plural laser emitting elements, and is configured to irradiate the recording target with laser light emitted from the plural laser emitting elements;

an irradiation condition adjusting unit configured to cause the laser irradiation device to emit laser light such that a part of an image dot recorded on the recording target moving relatively to the laser irradiation device overlaps an image dot adjacent thereto, and make a laser irradiation condition for when image dots forming a boundary between a colored portion and a non-colored portion are recorded, different from a laser irradiation condition for when the other image dots are recorded; and

an output control unit configured to control the irradiation with laser light by the laser irradiation device, based on the laser irradiation condition adjusted by the irradiation condition adjusting unit.

2. The image recording apparatus according to claim 1 , wherein

the irradiation condition adjusting unit makes laser irradiation start timing for when image dots forming a boundary between the colored portion and the non-colored portion are recorded, the boundary being at an upstream side in a relative movement direction of the recording target, later than the laser irradiation start timing for when the other image dots are recorded, and makes laser irradiation end timing for when image dots forming a boundary between the colored portion and the non-colored portion are recorded, the boundary being at a downstream side in the relative movement direction of the recording target, earlier than the laser irradiation end timing for when the other image dots are recorded.

3. The image recording apparatus according to claim 2 , wherein

the irradiation condition adjusting unit sets, based on a pitch of image dots in the relative movement direction and a radius of the image dots, laser irradiation timing by the laser irradiation device.

4. The image recording apparatus according to claim 3 , wherein

the irradiation condition adjusting unit sets the laser irradiation timing such that the following relation is satisfied, where the pitch of the image dots in the relative movement direction is P 1 , the radius of the image dots is R, and an amount of shift of the laser irradiation timing is W:

0.5×( R− 0.5 P 1)≤ W≤ 1.5×( R− 0.5 P 1).

5. The image recording apparatus according to claim 4 , wherein

the irradiation condition adjusting unit changes the laser irradiation timing, when power of laser light by the laser irradiation device has been changed.

6. The image recording apparatus according to claim 2 , wherein

the irradiation condition adjusting unit sets laser irradiation timing such that the following relation is satisfied, where a pitch of image dots in the relative movement direction is P 2 and a radius of the image dots is R:

1.1≤ P 2≤2 R≤ 1.5 P 2.

7. The image recording apparatus according to claim 1 , wherein

the irradiation condition adjusting unit makes power of laser light for when image dots forming a boundary between the colored portion and the non-colored portion in a direction intersecting the relative movement direction of the recording target are recorded, lower than power of laser light for when the other image dots are recorded.

8. The image recording apparatus according to claim 7 , wherein

the irradiation condition adjusting unit causes plural image dots to be continuously recorded by continuous lighting of laser light by the laser irradiation device, when an image dot adjacent, in the relative movement direction, to an image dot forming a boundary between the colored portion and the non colored portion in the direction intersecting the relative movement direction is present.

9. The image recording apparatus according to claim 1 , wherein

the non-colored portion is an outlined image.

10. The image recording apparatus according to claim 1 , wherein

the laser irradiation device has:

the plural laser emitting elements;

plural optical fibers that are provided correspondingly to the plural laser emitting elements and guide laser light emitted from the laser emitting elements, to the recording target;

plural laser emitting portions that are included correspondingly to the plural optical fibers and emit laser light; and

a laser array that holds the plural laser emitting portions in an array in a predetermined direction.

11. The image recording apparatus according to claim 1 , wherein

the irradiation condition adjusting unit sets power of laser light emitted from the laser irradiation device, according to temperature of the laser emitting elements.

12. An image recording method executed by an image recording apparatus that irradiates a recording target with laser light and records an image thereon, wherein

the image recording apparatus comprises:

a laser irradiation device that has plural laser emitting elements, and is configured to irradiate the recording target with laser light emitted from the plural laser emitting elements, and

the image recording method includes:

causing the laser irradiation device to emit laser light such that a part of an image dot recorded on the recording target moving relatively to the laser irradiation device overlaps an image dot adjacent thereto, and making a laser irradiation condition for when image dots forming a boundary between a colored portion and a non-colored portion are recorded, different from a laser irradiation condition for when the other image dots are recorded; and

controlling the irradiation with laser light by the laser irradiation device, based on the laser irradiation condition adjusted through the irradiation condition adjusting step.