JP2000025268A - Image-recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set a recording layer within a focal depth of laser beams even at a place in tight adhesion to a drum by shifting a focal position of the laser beams closer to a light source than a position of the recording layer of a recording medium. SOLUTION: A laser beam 100 is irradiated from the side of a base (supporting body) 3a. A focal position P1 of the laser beam 100 is shifted closer to a light source than a position of a recording layer 3b. Since the foal position P1 of the laser beam 100 is shifted towards the light source, the recording layer 3b can be set within a focal depth F of the laser beam 100 even where a recording medium 3 floats due to a foreign matter 120 or the like or even at a place in tight adhesion to a drum 2. Favorable images can be obtained accordingly. A shift amount X is not smaller than 5 μm and preferably not larger than the focal depth F of the laser beam 100, so that more favorable images can be obtained even where the recording medium 3 floats due to the foreign matter 120 or the like or even at the place in tight adhesion to the drum 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus for heat mode recording in which a recording medium is exposed using thermal energy of a laser.

[0002]

2. Description of the Related Art In heat mode recording in which a recording medium is exposed using thermal energy of a laser, a laser beam is applied to a recording medium wound around a rotating drum to apply heat to the drum or an optical system. In some cases, pixels of a gradation image are recorded on a recording medium as a dot array image while being moved in a direction substantially perpendicular to the rotation direction of.

[0003]

In such an image recording apparatus, when foreign matter such as dust is present on the drum, for example, the sheet floats and the focal position shifts to the light source side. By the way, the depth of focus of the laser beam is as very small as 20 μm or less, and foreign matter of this degree adversely affects an image, and cannot follow foreign matter and the like even by using autofocus.

That is, when the autofocus is not used, foreign matter such as dust is caught between the drum and the recording medium, or when the recording medium is loosened and wound around the drum, the recording medium floats slightly. It becomes out of focus.

When using auto focus,
Although it is possible to follow the gentle unevenness of the recording medium by autofocus, it cannot follow sudden changes. In particular, when the recording medium is wound around the drum by suction, when foreign matter or the like is caught, it is effective because abrupt irregularities occur near the foreign matter.

The present invention has been made in view of the above point, and it is possible to provide a recording layer within a focal depth of a laser beam in a place where a recording medium floats due to a foreign matter or the like or in a place where the recording medium is in close contact with a drum. It is intended to provide an image recording device.

[0007]

Means for Solving the Problems In order to solve the above problems and achieve the object, the present invention has the following constitution.

According to a first aspect of the present invention, there is provided an image recording apparatus for recording an image by applying a minute laser beam from a light source to a recording medium wound around a drum and applying heat thereto.
An image recording apparatus, wherein a focal position of the laser beam is shifted to a light source side from a position of a recording layer of the recording medium. ].

According to the first aspect of the present invention, the focal position of the laser beam is set to be smaller than the position of the recording layer of the recording medium.
Since the recording layer is shifted to the light source side, the recording layer can be provided within the depth of focus of the laser beam at a place where the recording medium floats due to a foreign substance or the like or at a place where the recording medium is in close contact with the drum, and a good image can be obtained.

According to a second aspect of the present invention, there is provided the image recording apparatus according to the first aspect, wherein the shift amount is not less than 5 μm and not more than the focal depth of the laser beam. ].

According to the second aspect of the present invention, even when the shift amount is 5 μm or more and the focus depth of the laser beam or less and the recording medium floats due to foreign matter or the like,
A more preferable and good image can be obtained even in a place close to the drum.

According to a third aspect of the invention, there is provided the image recording apparatus according to the second aspect, wherein the shift amount is 5 μm or more and 20 μm or less. ].

According to the third aspect of the present invention, the shift amount is 5 μm or more and 20 μm or less, and a more preferable and good image can be obtained even in a place where the recording medium floats due to foreign matter or the like or in a place where it is in close contact with the drum. be able to.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an image recording apparatus according to the present invention will be described with reference to the drawings, but the present invention is not limited to this embodiment.

FIG. 1 is a schematic diagram of an image recording apparatus, and FIG. 2 is a diagram for explaining image recording. The image recording apparatus 1 has a drum 2, and a recording medium 3 is wound around the drum 2. A multi-laser head 60 is arranged at a predetermined distance from the image recording surface. The image is recorded by rotating the drum 2 in the R direction and moving the multi laser head 60 in the drum axis direction in the X direction.

As described above, in the image recording apparatus 1, the recording medium is irradiated with a plurality of light beams by using the multi-laser head 60, and the light beam and the recording medium 3 are relatively moved (main scanning). A two-dimensional image is recorded by moving the light beam or the recording medium 3 in a direction substantially perpendicular to the direction (sub-scanning). In the image recording apparatus 1, banding unevenness may occur due to a light amount distribution for each channel n or a boundary between sub-scans.

The image recording apparatus 1 includes an image processing unit 10 for performing image processing on image data, a threshold mask 20 for converting multi-valued image data into a binary light beam modulation signal, Multi-valued image data is stored in a threshold mask unit 20
And a comparison unit 30 that converts the signal into a binary light beam modulation signal as compared with the threshold mask described above. The multi-laser head 60 is driven by the laser driving unit 50 to record a two-dimensional image. As described above, when changing the density gradation data to the binary data, the mask data having the relevant value is used.

FIG. 3 is a schematic diagram of a threshold mask having a minimum unit of 4 × 4. The threshold mask has a dither pattern (a) composed of an aggregate of the minimum unit, and converts the dither pattern (a) to image data (corresponding to 82 → 0.5D) (b)
When the image data is larger than the mask value, 0 is obtained, that is, a hole is formed to obtain binary image data (c). Also,
The dither pattern (a) is compared with the image data (corresponding to 8 → 1.2D) (d), and if the image data is larger than the mask value, 0, that is, a hole is formed to obtain binary image data (e).

Banding unevenness may occur due to variations in light quantity and beam diameter and unevenness in sub-scan feed. In order to scatter, the minimum units of the dither pattern are not aligned in a line but are shifted and arranged.

The multi-laser head 60 is provided with a plurality of laser beam light sources, and forms an image as a minute beam on the recording medium 3 via an imaging lens 61 by an imaging optical system having a predetermined magnification. .

4A and 4B are diagrams illustrating the embodiment of FIG. 4. FIG. 4A is a diagram illustrating a configuration in which a recording medium is irradiated with a laser beam to apply heat to record an image, and FIG. FIG. 4 is a diagram for explaining a configuration for performing image recording in a state where there is no image.
FIG. 3C is a diagram illustrating a configuration for performing image recording in a state where a foreign substance is present.

In the image recording apparatus 1 of this embodiment, a recording medium 3 wound around a drum 2 is irradiated with a laser beam from a light source to apply heat to record an image. As the recording medium 3, a heat mode recording medium is used, and the recording medium 3 basically includes three layers. When the recording layer 3b is irradiated with a laser beam focused to 5 to 10 μm from the side of the base (support) 3a, a micro ablation phenomenon occurs on the surface of the recording layer, and in this portion, the adhesive force between the base 3a and the recording layer 3b is reduced. It becomes substantially 0. By peeling off the peel sheet 3c after the exposure, the recording layer 3b is removed from the base 3a only in the laser irradiation part, and minute transparent dots are formed.

As a heat mode recording medium, a heat-fusible recording medium is also applicable. When this type of recording medium is used, the laser is irradiated from the peel sheet side of the recording medium. Since the recording layer is fused to the peel sheet by the thermal energy in the laser irradiation section, if the peel sheet is peeled off after exposure, transparent dots are formed in the laser irradiation section. The same effect can be obtained when a heat-fusible recording medium is used. However, this type of recording medium irradiates a laser from the side of the peel sheet, so that the support which causes interference is thin (10 to 10). (About 50 μm). Therefore, the spectrum half width is 0.2 n
If m or more, the effect of preventing interference is exhibited.

In this embodiment, the laser beam 10
0 is irradiated from the base (support) 3a side, and the focal position P1 of the laser beam 100 is shifted to the light source side from the position of the recording layer 3b.

By shifting the focal position P1 of the laser beam 100 to the light source side from the position of the recording layer 3b in this way, the recording medium 3 is lifted by the foreign matter 120 or the like as shown in FIG. 4C, the recording layer 3b can be provided within the depth of focus F of the laser beam 100, even at a place close to the drum 2 as shown in FIG.
Good images can be obtained.

The shift amount X is preferably not less than 5 μm and not more than the depth of focus F of the laser beam 100. Preferably, a good image can be obtained. The shift amount X is more preferably 5 μm or more and 20 μm or less.
Thus, even in a place where the recording medium 3 floats due to the above, or a place where the recording medium 3 is in close contact with the drum 2, it is possible to obtain a more preferable and good image.

In this image recording apparatus 1, the image formation by ablation is described in JP-A-9-104172, JP-A-9-104173, JP-A-9-104174 and JP-A-08-28.
2099, 08-337054, 08-33489
4, 08-337055, 08-337056, 08-337053, 08-310124, 09-
106079, 09-109462, 09-015
849, 09-226236, 09-28617
3, 09-300816, 09-300819, 09-309269, 10-052980, 10-
039519, Japanese Patent Application No. 10-28468, 10-0
37209, 10-040440, 10-0535
16, 10-055080, 10-055081,
10-068419, 10-068425, 10
Materials and methods described in -086042 can be used.

Further, in the image forming method by the fusion heat transfer,
WO-88004237, WO-9209441, WO
-9209442, WO-9209443, US-51
69476, US-5279889, EP-54433
5, US-5275914, WO-94123353, U
Materials and methods described in S-5328798 can be used.

For other image formation, an image forming element and an image forming method which can be addressed by an infrared laser can be used, as described in JP-A-07-270965 and JP-A-06-316.
177 and 9-127644 can be used.

[0030]

As described above, according to the first aspect of the present invention, since the focal position of the laser beam is shifted to the light source side from the position of the recording layer of the recording medium, the recording medium floats due to foreign matter or the like. The recording layer can be provided within the depth of focus of the laser beam both at a place and at a place close to the drum, and a good image can be obtained.

According to the second aspect of the present invention, the shift amount is 5 μm.
m or more and not more than the depth of focus of the laser beam,
A more favorable image can be obtained even in a place where the recording medium floats due to foreign matter or the like, or in a place where the recording medium is in close contact with the drum.

According to the third aspect of the present invention, the shift amount is 5 μm.
m or more and 20 μm or less, and it is possible to obtain a still more preferable and good image even in a place where the recording medium floats due to foreign matter or the like or in a place where the recording medium is in close contact with the drum.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image recording apparatus.

FIG. 2 is a diagram illustrating image recording.

FIG. 3 is a schematic diagram of a threshold mask having a minimum unit of 4 × 4 squares.

FIG. 4 is a diagram illustrating a configuration of an image recording apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image recording apparatus 2 Drum 3 Recording medium 3b Recording layer 10 Image processing part 20 Threshold mask part 30 Comparison part 50 Laser drive part 60 Multi laser head

Claims (3)

[Claims] An image recording apparatus for recording an image by irradiating a minute laser beam from a light source to a recording medium wound on a drum and applying heat to the recording medium, the focal position of the laser beam is set to the position of the recording medium. An image recording apparatus wherein the position of the recording layer is shifted to the light source side. 2. The image recording apparatus according to claim 1, wherein the shift amount is not less than 5 μm and not more than a focal depth of the laser beam. 3. The image recording apparatus according to claim 2, wherein said shift amount is 5 μm or more and 20 μm or less.