JP5121744B2 - Plate making apparatus and plate making method - Google Patents

Description

  The present invention relates to a plate making apparatus and a plate making method.

  A drum having a recording plate (recording medium) mounted on the outer peripheral surface is rotated in the main scanning direction, and a laser beam corresponding to image data of an image to be engraved (recorded) on the recording plate is sub-scanned perpendicular to the main scanning direction. 2. Description of the Related Art A plate making apparatus that engraves (records) a two-dimensional image on a recording plate by performing scanning in a direction is known.

  In such a plate making apparatus, as a problem when directly engraving a relief printing plate such as a flexographic printing plate or an intaglio printing plate such as a gravure plate with a laser beam, fine lines in shallow engraving (precision engraving) engraving a narrow area Both reproducibility of halftone dots and deep engraving (coarse engraving) for engraving a wide area can be improved.

  Since it is generally difficult to achieve both of these, both a laser beam with a small spot diameter for shallow engraving (precision engraving) and a high-power laser beam for deep engraving (rough engraving) are provided. A method of engraving separately is known (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3).

US6150629A US2006 / 0279794A1 JP-A-2005-224481

  However, engraving with higher definition is required.

  SUMMARY An advantage of some aspects of the invention is that it provides a plate making apparatus and a plate making method capable of engraving with higher definition than before.

  The plate making apparatus according to claim 1 is a plate making apparatus for engraving the surface of the recording medium by scanning the recording medium at a predetermined pixel pitch with a light beam, wherein the surface of the recording medium is convex. The optical power of the light beam for engraving a partial region or the entire region in the adjacent region adjacent to the convex portion to be left in the shape is set so that the upper surface of the convex portion is equal to or lower than the engraving threshold energy, and is set as the adjacent region The optical power of the light beam in the adjacent area close to the outside of the area is higher than that in the adjacent area.

  In the plate making apparatus according to claim 1, the light power of the light beam applied to a partial region or the entire region in the adjacent region adjacent to the convex portion that leaves the surface of the recording medium in a convex shape is applied to the upper surface of the convex portion. By lowering the exposure of the beam to be equal to or lower than the engraving threshold energy, engraving on the upper surface of the convex portion is prevented or suppressed.

  Therefore, for example, when the convex portion is linear, the width of the upper surface of the convex portion is brought close to a desired width (a desired width is ensured or substantially ensured). Alternatively, for example, when the convex portion has a dot shape (a two-dimensional shape such as a polygonal shape in plan view or a circular shape in plan view), the upper surface of the convex portion can be brought close to a desired size (width, etc.) or shape.

  Furthermore, in the adjacent area that is close to the outside of the engraving threshold energy in the adjacent area, the side surface of the convex portion has a steep angle by engraving with the light power of the light beam higher than that of the adjacent area. It becomes. In other words, the cross-sectional shape of the convex portion can be approximated to a rectangular shape.

  In this way, the upper surface of the convex portion can be brought close to a desired width, shape, size, etc., and the cross-sectional shape of the convex portion can be made closer to a rectangular shape. That is, the convex portion is engraved with high definition. Therefore, the reproducibility of fine lines and halftone dots in a printed matter printed on the recording medium after plate making is improved.

  In this way, by applying this configuration, even if the light beam diameter is large, the convex portion is engraved with high definition. Even when the light beam diameter is small, the convex portions are engraved with higher definition than when the present configuration is not applied.

  In addition, the amount by which the optical power of the light beam is increased in the proximity region is determined in consideration of the type of the recording medium.

  The adjacent area and the adjacent area are determined in consideration of the size of the convex portion, the beam diameter of the light beam, the pixel pitch, the type of the recording medium, and the like.

  The plate making apparatus according to claim 2 is characterized in that, in the configuration according to claim 1, the area in the adjacent area is one pixel or more.

  In the plate making apparatus according to claim 2, by setting the adjacent region to one pixel or more, the upper surface of the convex portion can be effectively brought closer to a desired width, shape, size, and the like. In addition, since the optical power is controlled in units of pixels, the optical power control is easy.

  The plate making apparatus according to claim 3 is characterized in that, in the configuration according to claim 1 or 2, the engraving is performed by pulse exposure with a pulse width of one pixel or less in the proximity region.

  In the plate making apparatus according to claim 3, engraving is performed by pulse exposure with a pulse width of one pixel or less, so that the inclination of the side surface of the convex portion becomes a steeper angle. In other words, the cross-sectional shape of the convex portion can be brought closer to the rectangular shape more effectively.

  Note that the pulse exposure referred to here refers to control of changing the optical power of the light beam from “off → on → off”, and the pulse width refers to the width (between) that is on.

  According to a fourth aspect of the present invention, in the configuration of the third aspect, the pulse width of the pulse exposure is 0.5 pixels or less.

  In the plate making apparatus according to claim 4, when the pulse width of the pulse exposure is 0.5 pixels or less, the inclination of the side surface of the convex portion becomes a steeper angle. In other words, the cross-sectional shape of the convex portion can be brought closer to the rectangular shape more effectively.

  According to a fifth aspect of the present invention, there is provided the plate making apparatus according to the third aspect, wherein the pulse width of the pulse exposure is 0.25 pixels or less.

  In the plate making apparatus according to claim 5, when the pulse width of the pulse exposure is 0.25 pixels or less, the inclination of the side surface of the convex portion becomes a steeper angle. In other words, the cross-sectional shape of the convex portion can be brought closer to the rectangular shape more effectively.

  The plate making apparatus according to claim 6 is the configuration according to any one of claims 1 to 5, wherein the light beam engraving the recording medium is emitted from a fiber array light source and then imaged. It is characterized by being a light beam condensed by a lens.

  In the plate making apparatus according to the sixth aspect, the recording medium is engraved with the light beam emitted from the fiber array light source and then condensed by the imaging lens. Therefore, for example, the cost is lower than an expensive light source such as a fiber laser or a CO2 laser.

  Even at such a low cost, the upper surface of the convex portion can be brought close to a desired width, shape, size, etc., and the cross-sectional shape of the convex portion can be made closer to a rectangular shape. That is, the reproducibility of fine lines and halftone dots in a printed matter printed on the recording medium after plate making is improved.

  The plate making apparatus according to claim 7, in the configuration according to any one of claims 1 to 6, when the convex portion has a polygonal shape in a plan view, an area that is set to be equal to or lower than an engraving threshold energy. Includes a region adjacent to at least one corner of the convex portion having a planar polygonal shape.

  In the plate making apparatus according to claim 7, the corners of the convex portions adjacent to the region set to be equal to or lower than the engraving threshold energy are more clearly formed (the corners are not chamfered).

  The plate making apparatus according to an eighth aspect is characterized in that, in the configuration according to the seventh aspect, the engraving threshold energy is set to be equal to or lower than the entire circumference of the convex portion having a rectangular shape in plan view. .

  In the plate making apparatus according to claim 8, since the upper surface of the convex portion is set to be equal to or lower than the engraving threshold energy over the entire circumference of the convex portion having a rectangular shape in plan view, the full-angle portion is formed more clearly. The

  A plate making apparatus according to a ninth aspect is characterized in that, in the configuration according to the seventh or eighth aspect, the convex portion has a rectangular shape in a plan view.

  In the plate making apparatus according to the ninth aspect, a desired convex portion having a rectangular shape in plan view can be obtained as compared with a case where the entire area adjacent to the corner portion of the convex portion having a rectangular shape in plan view is exposed.

  The plate making method according to claim 10 is a plate making method for engraving the surface of the recording medium by scanning the recording medium with a light beam at a predetermined pixel pitch, wherein the surface of the recording medium is convex. Reduce the optical power of the light beam engraving part or all of the adjacent area adjacent to the convex part to remain in the shape so that the upper surface of the convex part is below the engraving threshold energy, and close to the outside of the adjacent area The optical power of the light beam for engraving the adjacent area is higher than that of the adjacent area for engraving.

  In the plate making method according to the tenth aspect, the upper surface of the convex portion is brought close to a desired width, shape, size and the like, and the cross-sectional shape of the convex portion is made close to a rectangular shape. The convex part is engraved with high definition. Therefore, the reproducibility of fine lines and halftone dots in a printed matter printed on the recording medium after plate making is improved.

  The engraving threshold energy is the light energy of a light beam necessary for engraving the surface of the recording medium, and the recording medium is not engraved unless the energy is larger than the engraving threshold energy. In other words, the surface of the recording medium is not engraved even if a light beam having an engraving threshold energy or less is exposed. The engraving threshold energy differs depending on the type (material, etc.) of the recording medium.

  According to the plate-making apparatus of claim 1, the upper surface of the convex portion can be brought close to a desired width, shape, size, etc. and the cross-sectional shape of the convex portion can be made close to a rectangular shape, so that the recording medium can be engraved with high definition. It has an excellent effect of being able to.

  The plate making apparatus according to claim 2 has an excellent effect that the upper surface of the convex portion can be effectively brought closer to a desired width, shape, size, and the like.

  According to the plate-making apparatus of Claims 3-5, it has the outstanding effect that the cross-sectional shape of a convex part can be closely approached more rectangularly.

  According to the plate making apparatus of the sixth aspect, for example, it has an excellent effect that the cost can be suppressed as compared with an expensive light source such as a fiber laser.

  According to the control device of the seventh aspect, there is an excellent effect that the corners of the convex portions can be more clearly formed.

  According to the plate making apparatus of the eighth aspect, there is an excellent effect that the full-angle portion of the convex portion can be more clearly formed.

  According to the control device according to claim 9, compared to the case where all the areas adjacent to the corners of the convex portion of the rectangular shape in plan view are exposed, the convex portion can be brought close to a desired planar square shape. It has an excellent effect.

  According to the plate making method of claim 10, since the upper surface of the convex portion can be made close to a desired width, shape, size, etc., and the cross-sectional shape of the convex portion can be made close to a rectangular shape, It has an excellent effect that it can be engraved with high definition.

1 is a schematic configuration diagram (perspective view) showing a plate making apparatus according to an embodiment of the present invention. It is a perspective view which shows the fiber array part and optical fiber of a laser recording apparatus. It is a schematic diagram which shows the exposure part of a fiber array part. It is explanatory drawing for demonstrating the arrangement position and scanning line of an optical fiber edge part. It is the figure which looked at the plate-making apparatus in planar view. It is a block diagram which shows the structure of the control system of a plate-making apparatus. It is a flowchart which shows the outline | summary of the process at the time of recording an image with a laser recording apparatus. It is explanatory drawing which showed typically the principal part of the exposure head and the emitted laser beam. When the optical power control and the beam diameter D are not applied to the present invention, the right figure of (a) shows the spot diameter (spot shape) of the laser beam, and the left figure shows the optical power of the central section. It is a graph, and (b) schematically shows a change in optical power when scanning with a laser beam having the spot diameter (spot shape) shown in (a) to form a 21.2 μm convex fine line (a pixel area to be left). (A) shows the pixel exposure amount signal of the laser beam, (B) is a graph showing the integrated energy of the optical power of the cross section along the AA line of (b) of the laser beam, (C) is a figure which shows typically the cross-sectional shape along AA 'of (b) of the convex fine wire P. FIG. When the optical power control and the beam diameter D are not applied to the present invention, the right figure of (a) shows the spot diameter (spot shape) of the laser beam, and the left figure shows the optical power of the central section. It is a graph, and (b) schematically shows a change in optical power when scanning with a laser beam having the spot diameter (spot shape) shown in (a) to form a 21.2 μm convex fine line (a pixel area to be left). (A) shows the pixel exposure amount signal of the laser beam, (B) is a graph showing the integrated energy of the optical power of the cross section along the AA line of (b) of the laser beam, (C) is a figure which shows typically the cross-sectional shape along AA 'of (b) of the convex fine wire P. FIG. When the optical power control to which the present invention is applied and the beam diameter D is 20 μm, (A) shows a pixel exposure amount signal of the laser beam, and (B) shows an AA line of (b) of the laser beam. 6C is a graph showing the integrated energy of the optical power of the cross section along the line A, and FIG. 5C is a diagram schematically showing the cross-sectional shape along the line AA ′ of the convex thin line P in FIG. When the optical power control and the beam diameter D are not applied to the present invention, the right figure in (a) shows the spot diameter (spot shape) of the laser beam, and the left figure shows the optical power distribution in the central section. (B) is a diagram schematically showing a change in optical power when a 21.2 μm convex fine line is formed by scanning with a laser beam having the spot diameter (spot shape) shown in (a), (A) shows the pixel exposure amount signal of the laser beam, (B) is a graph showing the integrated energy of the optical power of the cross section along the line AA ′ of (b) of the laser beam, and (C). It is a figure which shows typically the cross-sectional shape along AA 'of (b) of the convex fine line P. FIG. When the optical power control and the beam diameter D are not applied to the present invention, the right figure in (a) shows the spot diameter (spot shape) of the laser beam, and the left figure shows the optical power distribution in the central section. (B) is a diagram schematically showing a change in optical power when a 21.2 μm convex fine line is formed by scanning with a laser beam having the spot diameter (spot shape) shown in (a), (A) shows the pixel exposure amount signal of the laser beam, (B) is a graph showing the integrated energy of the optical power of the cross section along the line AA ′ of (b) of the laser beam, and (C). It is a figure which shows typically the cross-sectional shape along AA 'of (b) of the convex fine line P. FIG. (A) shows the pixel exposure amount signal of the laser beam and (B) shows the integrated energy of the optical power of the laser beam when the optical power control to which the present invention is not applied and the beam diameter D is 40 μm. It is a graph and (C) is a figure which shows typically the section shape of convex fine line P. (A) shows the pixel exposure amount signal of the laser beam and (B) shows the integrated energy of the optical power of the laser beam when the optical power control to which the present invention is applied and the beam diameter D is 40 μm. (C) is a figure which shows typically the cross-sectional shape of the convex fine wire P. FIG. (A) shows the pixel exposure amount signal of the laser beam and (B) shows the integrated energy of the optical power of the laser beam when the optical power control to which the present invention is applied and the beam diameter D is 20 μm. (C) is a figure which shows typically the cross-sectional shape of the convex fine wire P. FIG. (A) shows the pixel exposure amount signal of the laser beam and (B) shows the integrated energy of the optical power of the laser beam when the optical power control to which the present invention is applied and the beam diameter D is 20 μm. (C) is a figure which shows typically the cross-sectional shape of the convex fine wire P. FIG. (A) shows the pixel exposure amount signal of the laser beam and (B) shows the integrated energy of the optical power of the laser beam when the optical power control to which the present invention is applied and the beam diameter D is 20 μm. (C) is a figure which shows typically the cross-sectional shape of the convex fine wire P. FIG. (A) shows the pixel exposure amount signal of the laser beam and (B) shows the integrated energy of the optical power of the laser beam when the optical power control to which the present invention is not applied and the beam diameter D is 40 μm. It is a graph and (C) is a figure which shows typically the section shape of convex fine line P. It is explanatory drawing explaining optical power control in the case of forming a convex point of planar view rectangular shape by applying this invention. It is explanatory drawing explaining optical power control in the case of forming a convex point of planar view rectangular shape by applying this invention. It is a figure which shows the convex point part at the time of forming the convex point of planar view rectangular shape by the optical power control of FIG. It is a figure which shows the convex point part at the time of forming the convex point of planar view rectangular shape by the optical power control of FIG. It is explanatory drawing explaining optical power control in the case of forming a convex point of planar view rectangular shape by applying this invention.

  Hereinafter, the configuration of the plate making apparatus 11 according to the embodiment of the present invention will be described. The plate making apparatus 11 rotates a drum 50 having a recording plate F (recording medium) mounted on its outer peripheral surface in the main scanning direction, and a plurality of images corresponding to image data of an image to be engraved (recorded) on the recording plate F. The two-dimensional image is engraved (recorded) on the recording plate at a high speed by scanning the exposure head 30 in the sub-scanning direction orthogonal to the main scanning direction at a predetermined pitch while simultaneously emitting the laser beam. Making a plate. Further, when leaving a narrow area (thin lines, halftone dots, etc.), the recording plate F is shallowly engraved (precision engraving), and when leaving a wide area, the recording plate F is deeply engraved (coarse engraving).

  FIG. 1 is a schematic configuration diagram (perspective view) showing a plate making apparatus 11. As shown in FIG. 1, the plate making apparatus 11 is rotationally driven in the direction of arrow R in FIG. 1 so that a recording plate F on which an image is recorded by engraving with a laser beam is mounted and the recording plate F moves in the main scanning direction. The drum 50 and the laser recording apparatus 10 are configured. The laser recording apparatus 10 includes a light source unit 20 as a fiber array light source that generates a plurality of laser beams, an exposure head 30 that exposes a plurality of laser beams generated by the light source unit 20 onto a recording plate F, and an exposure head 30. And an exposure head moving unit 40 that moves along the sub-scanning direction. The rotation direction R of the drum 50 is the main scanning direction, and the direction (details will be described later) in which the exposure head 30 moves along the axial direction (longitudinal direction) of the drum 50 indicated by the arrow S is the sub-scanning direction. The

  The light source unit 20 includes 32 semiconductor lasers 21A and 21B (64 in total) each composed of a broad area semiconductor laser in which one end portions of the optical fibers 22A and 22B are individually coupled, and the semiconductor lasers 21A and 21A, Light source boards 24A and 24B having 21B disposed on the surface, and a plurality of adapters for SC type optical connectors 25A and 25B (the same number as semiconductor lasers 21A and 21B) are provided at one end of the light source boards 24A and 24B. LD driver circuit for horizontally driving the semiconductor lasers 21A and 21B according to the image data of the image to be engraved (recorded) on the recording plate F while being horizontally attached to the other end portions of the adapter substrates 23A and 23B and the light source substrates 24A and 24B. LD driver boards 27A and 27B provided with a reference numeral 26 (see FIG. 6), It is gills.

  SC optical connectors 25A and 25B are provided at the other ends of the optical fibers 22A and 22B, respectively. The SC optical connectors 25A and 25B are connected to the adapter boards 25A and 25B. Therefore, the laser beams emitted from the respective semiconductor lasers 21A and 21B are transmitted to the SC type optical connectors 25A and 25B connected to the adapter boards 23A and 23B through the optical fibers 22A and 22B, respectively.

  In addition, output terminals for driving signals of the semiconductor lasers 21A and 21B in the LD driver circuit 26 provided on the LD driver substrates 27A and 27B are individually connected to the semiconductor lasers 21A and 21B. The driving of 21B is individually controlled by the LD driver circuit 26 (see FIG. 6).

  On the other hand, the exposure head 30 is provided with a fiber array unit 300 (see FIG. 2) that collectively emits laser beams emitted from the plurality of semiconductor lasers 21A and 21B. The fiber array unit 300 includes laser beams emitted from the semiconductor lasers 21A and 21B by a plurality of optical fibers 70A and 70B connected to SC type optical connectors 25A and 25B connected to adapter boards 23A and 23B, respectively. Is transmitted.

  FIG. 3 shows a view of the exposure unit 280 (see FIG. 2) of the fiber array unit 300 viewed in the direction of arrow A shown in FIG. As shown in FIG. 3, the exposure unit 280 of the fiber array unit 300 has two bases 302A and 302B. The bases 302A and 302B are formed on one side so that the same number of semiconductor lasers 21A and 21B, that is, 32 V-shaped grooves 282A and 282B are adjacent to each other at a predetermined interval. The bases 302A and 302B are arranged so that the V-shaped grooves 282A and 282B face each other.

  One optical fiber end 71A at the other end of the optical fiber 70A is fitted into each V-shaped groove 282A of the base 302A. Similarly, one optical fiber end 71B at the other end of each optical fiber 70B is fitted into each V-shaped groove 282B of the base 302B. Therefore, from the exposure unit 280 of the fiber array unit 300, a plurality of laser beams emitted from the semiconductor lasers 21A and 21B, in this embodiment, 64 (32 × 2) are emitted simultaneously.

  That is, the fiber array unit 300 of the present embodiment is configured by arranging a plurality (32 in the present embodiment × 2 = 64 in total) of optical fiber end portions 71A and 72B in a straight line along a predetermined direction. The optical fiber end groups 301A and 301B are configured to be provided in two rows in parallel to a direction orthogonal to the predetermined direction.

  As shown in FIGS. 1 and 3, in the laser recording apparatus 10 according to the present embodiment, the fiber array unit 300 (exposure head 30) configured as described above has the predetermined direction with respect to the sub-scanning direction. And inclined. Further, as shown in FIGS. 3 and 4, when the fiber array unit 300 is viewed in the main scanning direction, the optical fiber end group 301A and the optical fiber end group 301B are arranged without overlapping in the sub scanning direction. It is arranged.

  As shown in FIG. 1, in the exposure head 30, a collimator lens 32, an aperture member 33, and an imaging lens 34 are arranged in order from the fiber array unit 300 side. The opening member 33 is arranged so that the opening is positioned at the far field as viewed from the fiber array unit 300 side. As a result, the same light quantity limiting effect can be given to all laser beams emitted from the optical fiber end portions 71A and 71B of the plurality of optical fibers 70A and 70B in the fiber array unit 300.

  In the present embodiment, a multimode optical fiber having a relatively large core diameter is applied to the optical fibers 22A and 22B in order to increase the output of the laser beam. Specifically, in this embodiment, the core diameter is 105 μm. The semiconductor lasers 21A and 21B use 8.5w (6397-L3) as the maximum output. The core diameters of the optical fibers 70A and 70B are set to 105 μm.

  As shown in FIG. 8, the laser beam is imaged in the vicinity of the exposure surface (front surface) FA of the recording plate F by the imaging means composed of the collimator lens 32 and the imaging lens 34 (the opening member 33 is shown in FIG. 8). (Not shown in FIG. 8). In the present embodiment, it is desirable from the viewpoint of fine line reproducibility and the like that the imaging position (imaging position) X is set on the exposure surface FA. The laser beam emitted from the optical fiber end 71A (optical fiber end group 301A) is used as a laser beam LA, and the laser beam emitted from the optical fiber end 72B (optical fiber end group 301B) is used as a laser beam. LB. In addition, when it is not necessary to distinguish both, it is simply described as “laser beam”.

  Then, an optical fiber end 71B at the end of the optical fiber end group 301B is arranged next to the optical fiber end 71A at the end of the optical fiber end group 301A (see also FIG. 3). In FIG. 4, the number of the optical fiber end portions 71 </ b> A and 71 </ b> B is smaller than the actual number for easy understanding.

  As shown in FIG. 5, a recording plate F on which an image is recorded by engraving with a laser beam is mounted on the outer peripheral surface of a drum 50 that is driven to rotate in the direction of arrow R. The recording plate F is mounted on the outer peripheral surface of the drum 50 by a belt-like chuck member 98 whose longitudinal direction is the rotation axis direction of the drum 50. More specifically, the recording plate F is mounted on the outer peripheral surface of the drum 50 by attaching the chuck member 98 to the drum 50 so as to press the upper portion of the end portion FT of the recording plate F. The chuck member 98 is a non-recording area.

  As shown in FIGS. 1 and 5, the exposure head moving unit 40 includes a ball screw 41 and two rails 42 (see FIG. 1) arranged so that the longitudinal direction thereof is along the sub-scanning direction. By operating the sub-scanning motor 43 that rotationally drives the ball screw 41, the pedestal portion 310 provided with the exposure head 30 can be moved in the sub-scanning direction while being guided by the rails 42. Further, the drum 50 can be rotated in the direction of the arrow R in FIG. 1 by operating a main scanning motor 51 (see FIG. 6), whereby main scanning is performed. The exposure head 30 is provided on the pedestal portion 310.

  In the present embodiment, as described above, exposure and scanning are performed with 64 laser beams LA and LB at a time.

  Next, the configuration of the control system of the plate making apparatus 11 (see FIG. 1) according to the present embodiment will be described.

  As shown in FIG. 6, the control system of the plate making apparatus 11 includes an LD driver circuit 26 that drives the semiconductor lasers 21A and 21B according to image data, a main scanning motor drive circuit 81 that drives the main scanning motor 51, and A sub-scanning motor driving circuit 82 for driving the sub-scanning motor 43; an actuator driving circuit 299 for driving the actuator 304; a main scanning motor driving circuit 81; a sub-scanning motor driving circuit 82; a control circuit 80 for controlling the actuator driving circuit; It is equipped with. Image data representing an image to be engraved (recorded) on the recording plate F is supplied to the control circuit 80.

  Next, an outline of the process of engraving (recording) on the recording plate F by the plate making apparatus 11 (see FIG. 1) configured as described above will be described. FIG. 7 is a flowchart showing a flow of processing when image recording is performed by the plate making apparatus 11.

  As shown in FIG. 7, first, image data of an image to be engraved (recorded) on the recording plate F is transferred from the image memory (not shown) temporarily stored to the control circuit 80 (step 100). The control circuit 80 sends the adjusted signal to the LD driver circuit 26, the main data based on the transferred image data, resolution data indicating a predetermined resolution of the recorded image, data indicating shallow engraving, deep engraving, and the like. This is supplied to the scanning motor drive circuit 81, the sub-scan motor drive circuit 82, and the actuator drive circuit 299.

  Next, the main scanning motor drive circuit 81 controls the main scanning motor 51 so as to rotate the drum 50 in the direction of arrow R in FIG. 1 based on the signal supplied from the control circuit 80 (step 102).

  The sub-scanning motor drive circuit 82 sets a feed interval in the sub-scanning direction of the exposure head 30 by the sub-scanning motor 43 (step 104).

  Next, the LD driver circuit 26 controls driving of the semiconductor lasers 21A and 21B according to the image data (step 106).

  The laser beams LA and LB emitted from the respective semiconductor lasers 21A and 21B are optical fiber end portions 71A of the fiber array section 300 via the optical fibers 22A and 22B, the SC type optical connectors 25A and 25B, and the optical fibers 70A and 70B. 1, 71 B, and as shown in FIGS. 1 and 8, the collimator lens 32 converts the light into a substantially parallel light beam. Then, the light quantity is limited by the aperture member 33, and the recording plate on the drum 50 is passed through the imaging lens 34. An image is formed (condensed) in the vicinity of the F exposure surface FA (the imaging surface X and FA may coincide).

  In this case, beam spots are formed on the recording plate F in accordance with the laser beams LA and LB emitted from the respective semiconductor lasers 21. With these beam spots, the exposure head 30 is fed in the sub-scanning direction at the pitch of the feed interval set in step 104 described above, and the resolution is determined by the resolution data by the rotation of the drum 50 started in step 102 described above. A two-dimensional image having the resolution shown is engraved (formed) on the recording plate F (step 108).

  When the engraving (recording) of the two-dimensional image on the recording plate F is completed, the main scanning motor drive circuit 81 stops the rotation driving of the main scanning motor 51 (step 110), and then the present process ends.

  Next, the optical power control of the laser beams LA and LB in step 108 will be described, and the operation and effect of this embodiment will be described.

  As shown in FIG. 4, when the optical fiber end group 301A and the optical fiber end group 301B are viewed in the main scanning direction, the distance between the optical fiber end parts 71A and 71B, that is, the distance between the scanning lines K (pixel pitch). ) Is 10.58 μm (resolution: 2400 dpi). In other words, one pixel is 10.58 μm.

  Also, a case where the convex fine line P that leaves the surface FA of the recording plate F in a convex shape is formed will be described. The convex thin line P has a longitudinal direction in the sub-scanning direction and a desired width (width in the main scanning direction) of 21.2 μm.

  First, the case where the spot diameter D of the laser beam is φ20 μm will be described with reference to FIGS.

  In each figure, the right figure in (a) shows the spot diameter (spot shape) of the laser beam, and the left figure is a graph showing the optical power distribution in the central section. (B) is a figure which shows typically the optical power change at the time of scanning with the laser beam of the spot diameter (spot shape) shown to (a) and forming the 21.2 micrometer convex fine line P. FIG. The darker the color, the stronger the optical power, and the thinner the color, the weaker the optical power. (A) shows a pixel exposure amount signal of the laser beam. (B) is a graph which shows the integrated energy of the optical power of the cross section along the AA line of (b) of a laser beam. (C) is a figure which shows typically the cross-sectional shape (vertical cross-sectional shape when a convex direction is made into an upper direction) along AA of (b) of the convex fine wire P. FIG. Further, G in the drawing indicates one pixel width (10.58 μm). In FIG. 11, the figures corresponding to (a) and (b) are omitted, and only the figures corresponding to (A) to (C) are shown. Furthermore, the arrow R direction in the figure is the laser beam scanning direction (in this embodiment, the main scanning direction).

  The engraving threshold energy (see (B)) is the energy of the laser beam necessary for engraving the surface of the recording plate F, and engraving the recording plate F if the energy is not larger than the engraving threshold energy. I can't. In other words, if the energy is below the engraving threshold energy, the surface of the recording plate F is not engraved even when the laser beam is irradiated. The engraving threshold energy varies depending on the type (material, etc.) of the recording plate F.

  FIG. 9 shows a case where optical power control is performed with the pixel exposure amount signal of the laser beam turned off only in the portion corresponding to the 21.2 μm wide convex fine line P (optical power control to which the present invention is not applied). . In this case, even if the pixel exposure amount signal of the laser beam is turned off, the region of the convex fine line P is exposed. For this reason, as shown in FIG. 9C, the width of the upper surface P5 of the convex fine line P is a portion that is equal to or less than the engraving threshold energy, and thus the cross-sectional shape of the convex fine line P is substantially trapezoidal. Therefore, the width of the upper surface P5 of the convex fine line P is less than the desired 21.2 μm.

  FIG. 10 shows a case where optical power control is performed by turning off the pixel exposure signal of the laser beam for one pixel (both for two pixels) on the upstream and downstream sides in the scanning direction of the 21.2 μm wide convex thin line P. Is shown. In this case, since the convex fine line P portion is not completely exposed, the width of the upper surface P5 of the convex fine line P can be brought close to the desired 21.2 μm (21.2 μm width is ensured or substantially ensured). In addition, since the width of the upper surface P5 of the convex thin line P is a portion that is equal to or less than the engraving threshold energy, the width is exactly the α1 portion in the drawing. Further, as shown in FIG. 10C, the base of the trapezoid is about 20 μm.

  In the case of FIG. 10, the width of the upper surface P5 of the convex fine line P can be brought close to the desired value of about 20 μm. However, as shown in FIG. The inclination angle of P2 is gentle. That is, the angle of the edge portion E formed by the upper surface P5 and the side wall surfaces P1 and P2 is laid down (the angle is larger than 90 °). However, in order to print the fine line after printing with high definition, it is necessary to raise this edge portion E (need to be close to 90 °). That is, it is necessary to make the inclination angles of the side wall surfaces P1 and P2 close to vertical.

  Therefore, in the plate making apparatus 11 of this embodiment, the present invention is applied, and the inclination angle of the wall surfaces P1 and P2 is increased by increasing the optical power for one pixel outside the laser beam as shown in FIG. Is close to vertical. That is, the edge portion E is more erected (closer to 90 °). As a result, the cross-sectional shape of the convex fine line P (vertical cross section when the convex direction is the upward direction as shown in the figure) can be made closer to a rectangular shape.

  In addition, since the width of the upper surface P5 of the convex thin line P is a portion that is equal to or less than the engraving threshold energy, the width of the α2 portion in the figure is wide, but the inclination angles of the wall surfaces P1 and P2 are close to vertical. , Very little and no problem. Further, the width for raising the optical power of the laser beam is increased or the width for turning off the pixel exposure amount signal is slightly narrowed so that the width is narrowed by α2 (to bring the width closer to the desired 21.2 μm). Etc., and may be adjusted.

  As described above, in the plate making apparatus 11 of this embodiment, the optical power is turned off by one pixel on the upstream side and the downstream side in the scanning direction in the adjacent region adjacent to the convex fine line P, and the laser beam is close to the outside where the laser beam is turned off. By increasing the optical power of one pixel (proximity region), the inclination angles of the wall surfaces P1 and P2 are made closer to vertical (the edge portion E is more upright (closer to 90 °)).

  Thus, even if the beam diameter D is as large as 20 μm (even if the beam diameter D is larger than one pixel), the width of the upper surface P5 of the convex thin line P is desired by applying the optical power control of the present invention. In addition to being able to approach the width (21.2 μm in the present embodiment), the cross-sectional shape of the convex thin line P can be approximated to a rectangular shape. That is, the convex fine line P can be engraved with high precision. Therefore, it is possible to improve the reproducibility of fine lines in the printed matter printed on the recording plate F after plate making.

  As shown in FIG. 18, the upstream side and the downstream side in the scanning direction of the convex thin line P having a width of about 20 μm are each one pixel (both are two pixels), and the pixel exposure signal of the laser beam is turned off (the optical power is reduced). Instead of setting to 0 (zero)), the optical power control may be performed so that the exposure is performed with the engraving threshold energy or less.

  Next, the case where the spot diameter D of the laser beam is set to φ40 μm will be described with reference to FIGS.

  In each figure, as in the case where the spot diameter D is φ20 μm, the right figure in (a) shows the spot diameter (spot shape) of the laser beam, and the left figure is a graph showing the optical power distribution in the central section. (B) is a figure which shows typically the optical power change at the time of scanning with the laser beam of the spot diameter (spot shape) shown to (a), and forming the 20 micrometer convex fine wire P. FIG. The darker the color, the stronger the amount of light, and the thinner the color, the weaker the optical power. (A) shows a pixel exposure amount signal of the laser beam. (B) is a graph which shows the integrated energy of the optical power of the cross section along the AA line of (b) of a laser beam. (C) is a figure which shows typically the cross-sectional shape (vertical cross section when a convex direction is made into an upper direction) along AA of (b) of the convex fine wire P. FIG. Further, G in the drawing indicates one pixel width (10.58 μm). In FIGS. 14 and 15, the figures corresponding to (a) and (b) are omitted, and only the figures corresponding to (A) to (C) are shown. Furthermore, the arrow R direction in the figure is the laser beam scanning direction (in this embodiment, the main scanning direction).

  FIG. 12 shows a case where optical power control is performed by turning off the exposure signal of the laser beam only for the portion corresponding to the 21.2 μm wide convex thin line P (optical power control to which the invention is not applied). In this case, even if the pixel exposure amount signal of the laser beam is turned off, even the convex fine line P is exposed. Further, since the spot diameter D is as large as φ40 μm, the laser beam overlaps on the convex fine line P as shown in FIG. 12 (B), and the accumulated energy becomes large. Therefore, as shown in FIG. P is not formed.

  FIG. 13 shows a case where optical power control is performed by turning off the pixel exposure signal of the laser beam for one pixel (both for two pixels) on the upstream and downstream sides in the scanning direction of the 21.2 μm wide convex thin line P. (Optical power control to which the present invention is not applied). Even in this case, since the spot diameter D is as large as φ40 μm, even the convex fine line P is exposed. For this reason, as shown in FIG. 13C, since the width of the upper surface P5 of the convex fine line P becomes a portion that is equal to or smaller than the engraving threshold energy, the cross-sectional shape is substantially trapezoidal. Therefore, the width of the upper surface P5 of the convex fine line P is less than the desired 20 μm.

  FIG. 14 further shows optical power control in which the pixel exposure amount signal of the laser beam is turned off for two pixels (both for four pixels) on the upstream and downstream sides in the scanning direction of the 21.2 μm wide convex thin line P. (Optical power control to which the present invention is not applied). In this case, since the convex thin line P portion is not almost completely exposed, the width of the upper surface P5 of the convex fine line P can be made close to the desired 21.2 μm.

  However, in the case of FIG. 14, the width of the upper surface P5 of the convex fine line P can be brought close to the desired 21.2 μm. However, as shown in FIG. 14C, the upstream side and the downstream side of the convex fine line P in the scanning direction. The inclination angles of the wall surfaces P1 and P2 are gentle. That is, the angle of the edge portion E formed by the upper surface P5 and the side wall surfaces P1 and P2 is laid down (the angle is larger than 90 °). In order to make fine lines after printing have higher definition, it is necessary to raise this edge portion E (need to be close to 90 °). That is, it is necessary to make the inclination angles of the side wall surfaces P1 and P2 close to vertical.

  Therefore, as in the case where the beam diameter D is 20 μm, the present invention is applied to increase the optical power for one pixel outside the laser beam as shown in FIG. By making the inclination closer to vertical (by raising the edge portion E (by approaching 90 °)), the cross-sectional shape of the convex thin line P can be made closer to a rectangular shape.

  As described above, even if the beam diameter D is as large as 40 μm (even if the beam diameter D is larger than one pixel and larger than the width of the convex fine line P), by applying the present invention, The width of the upper surface P5 can be made closer to the desired 20 μm, and the cross-sectional shape of the convex fine line P can be made closer to a rectangular shape. That is, even if the beam diameter D is as large as 40 μm, the convex fine line P can be engraved with high precision. Therefore, the reproducibility of fine lines in the printed matter printed on the recording plate F after plate making is improved.

  In addition, as shown in FIG. 19, the pixel exposure amount signal of the laser beam is not turned off for two pixels (both for four pixels) on the upstream and downstream sides in the scanning direction of the convex thin line P having a width of about 20 μm. You may perform optical power control which exposes with below engraving threshold energy. In this case as well, by increasing the amount of power for one outer pixel with the laser beam equal to or lower than the engraving threshold energy and making the slopes of the wall surfaces P1 and P2 close to vertical (by making the edge E more upright (closer to 90 °). )), The cross-sectional shape of the convex fine wire P is made close to a rectangular shape.

  The laser beam diameter D may be the same between the laser beam LA and the laser beam LB (see FIG. 8) or may be different. For example, the beam diameter D of the laser beam LA may be 20 μm for shallow carving, and the laser beam LB may be 40 μm for deep carving.

  Next, when increasing the amount of power for one pixel outside the laser beam turned off (or less than the engraving threshold energy), pulse exposure is performed to make the inclination of the wall surfaces P1 and P2 closer to the vertical (edge) The optical power control will be described by raising the portion E more (by approaching 90 °). In other words, the optical power control that brings the cross-sectional shape of the convex thin line P closer to a rectangular shape will be described.

  Here, an example in which the beam diameter D is about 20 μm will be described, but the same applies even when the beam diameter D is 40 μm.

  FIG. 16 shows a case where pulse exposure is performed with a pulse width of 0.5 pixels. As can be seen from FIG. 16, it is understood that the inclination of the wall surfaces P1 and P2 can be made more vertical by performing pulse exposure. At this time, it is desirable to increase the maximum value of the optical power so that the integrated energy is substantially the same as in FIG.

  Further, FIG. 17 shows a case where pulse exposure is performed with a pulse width of 0.25 pixel. As can be seen from FIG. 17, it can be seen that the inclination of the wall surfaces P1 and P2 can be made more vertical by further narrowing the pulse width. At this time, it is desirable to further increase the maximum value of the optical power so that the integrated energy is substantially the same as in the case of FIG. 11 (FIG. 16).

  In the above embodiment, the region for controlling the optical power is performed on the upstream side and the downstream side in the main scanning direction, respectively, but may be applied only to either the upstream side or the downstream side.

  Further, the optical power control according to the present invention may be applied to at least one of the upstream side and the downstream side in the sub-scanning direction instead of the upstream side and the downstream side in the scanning direction (main scanning direction). In other words. The width of the upper surface P5 in the cross section along the line B-B 'shown in FIG. 9 may be close to the desired 21.2 μm, and the cross sectional shape may be close to a rectangular shape (side wall surfaces P3 and P4 are also close to the vertical).

  Up to now, the convex thin line P has been described. Next, optical power control in the case of forming a convex point Q having a rectangular shape in plan view (leaving the convex point Q) will be described. Here, the size of the desired convex point Q is 21.2 μm × 21.2 μm. Further, the control of the beam diameter D, the pulse width, and the like are the same as those of the convex thin line P described so far, and the description thereof is omitted.

  FIG. 20 shows that one pixel (pixel A, pixel B, pixel C, pixel D) adjacent to the corners QA, QB, QC, QD of the convex point Q does not turn off the laser beam (below the threshold energy). It is explanatory drawing explaining the case where it sets to the proximity | contact area | region R which raised power. FIG. 22 is a diagram schematically showing the shape of the convex point Q in plan view when the optical power is controlled as shown in FIG. In FIG. 21, the laser beam is turned off for one pixel (including pixel A, pixel B, pixel C, and pixel D) over the entire circumference of the convex point Q, and the optical power is increased over the entire outer circumference. It is explanatory drawing explaining the case where it sets to the proximity | contact area | region R. FIG. FIG. 23 is a diagram schematically showing the shape of the convex portion Q when the optical power is controlled as shown in FIG. In FIG. 24, one pixel adjacent to a part of corners of the convex point Q (in this case, corners QA, QB, QC, QD) is set in the proximity region R where the optical power is increased without turning off the laser beam. It is explanatory drawing explaining the case where it did.

  As shown in FIG. 20, when exposure is performed without turning off the laser beam for one pixel (pixel A, pixel B, pixel C, pixel D) adjacent to the corners QA, QB, QC, QD of the convex point Q, As shown in FIG. 22, the shape of the convex point Q does not sufficiently approach the rectangular shape in plan view. Note that FIG. 22 is shown deformed (distorted) for easy understanding.

  On the other hand, as shown in FIG. 21, the laser beam is turned off for one pixel (including pixel A, pixel B, pixel C, and pixel D) over the entire circumference of the convex point Q, and the outer circumference thereof. When the optical power is increased over the range, the shape of the convex point Q approaches a rectangular shape in plan view as shown in FIG.

  As shown in FIGS. 20 and 22, the laser beam is not turned off for one pixel (pixel A, pixel B, pixel C, pixel D) adjacent to the corners QA, QB, QC, QD of the convex point Q. The case where the optical power is increased is also included in the present invention.

  In addition, as shown in FIG. 24, the present invention also includes a case where the optical power of one pixel adjacent to some corners QA, QB, QD of the convex point Q is increased without turning off the laser beam. Also in this case, as shown in FIG. 24, it is preferable to increase the optical power of the laser beam over the entire circumference (as shown in FIG. 21).

  However, as described above, as shown in FIGS. 21 and 23, adjacent to the corners QA, QB, QC, and QD of the convex point Q are adjacent to one pixel (pixel A, pixel B, pixel C, and pixel D). By not exposing the region to be exposed (set so that the upper surface of the convex portion Q is equal to or lower than the threshold energy), the convex point portion Q having a desired rectangular shape in plan view can be obtained more effectively.

  Even in the case where the shape in plan view is a convex point portion other than a rectangular shape in plan view (for example, a circular shape or a triangular shape), the surface of the recording medium is partially or entirely in the adjacent region adjacent to the convex point portion ( The present invention is not applied by setting the optical power of the light beam engraving over the entire circumference of the convex point portion so that the exposure of the light beam applied to the upper surface of the convex point portion is equal to or lower than the engraving threshold energy. Compared to the case, it can be closer to the convex portion of the desired size and shape.

  In addition, in the case where the shape in plan view is a polygonal point other than the plan view rectangular shape (for example, a triangular shape or a pentagonal shape), the region set below the engraving threshold energy in the adjacent region By including the area adjacent to the corner of the convex part of the projection, the corner of the convex part is formed more clearly than when exposing all the areas adjacent to the corner of the convex part of the polygonal shape in plan view. (The corners are not chamfered).

  In addition, this invention is not limited to the said embodiment.

  In this embodiment, the laser exposure system that emits the laser beam is a fiber array exposure system that is emitted from the light source unit 20 (fiber array light source) and then condensed by the imaging lens 34. Compared with a laser exposure system using a laser or a CO2 laser light source, the cost is low.

  As described above, the engraving threshold energy is the light energy of a light beam necessary for engraving the surface of the recording medium, and the recording medium is not engraved unless the energy is larger than the engraving threshold energy. The engraving threshold energy is a technique that is not disclosed in the prior art, and by taking this into account, finer engraving is possible.

DESCRIPTION OF SYMBOLS 10 Laser recording apparatus 11 Plate making apparatus 20 Light source unit (fiber light source)
30 exposure head 34 imaging lens 50 drum 70A optical fiber 70B optical fiber 71A optical fiber end 71B optical fiber end 300 fiber array LA laser beam (light beam)
LB Laser beam (light beam)
F Recording plate (recording medium)
FA exposure surface (surface of recording medium)
P Convex wire (convex part)
Q Convex point (convex)
QA Corner QB Corner QC Corner QD Corner

Claims (10)

A plate making apparatus for engraving a plate of the recording medium by scanning the recording medium with a light beam at a predetermined pixel pitch,
The optical power of the light beam for engraving a partial area or the entire area in the adjacent area adjacent to the convex part that leaves the surface of the recording medium convex is set so that the upper surface of the convex part is equal to or lower than the engraving threshold energy. ,
The plate making apparatus characterized in that the optical power of the light beam in the adjacent area close to the outside of the adjacent area is higher than that in the adjacent area.   2. The plate making apparatus according to claim 1, wherein an area of the adjacent area that is equal to or lower than the engraving threshold energy is 1 pixel or more.   3. The plate making apparatus according to claim 1, wherein the proximity region is engraved by pulse exposure with a pulse width of 1 pixel or less. 4.   The plate making apparatus according to claim 3, wherein a pulse width of the pulse exposure is 0.5 pixel or less.   The plate making apparatus according to claim 3, wherein a pulse width of the pulse exposure is 0.25 pixels or less.   6. The light beam for engraving the recording medium is a light beam that is emitted from a fiber array light source and then condensed by an imaging lens. The plate making apparatus as described in the item. When the convex portion is a polygonal shape in plan view,
The region set so as to be equal to or lower than the engraving threshold energy includes a region adjacent to at least one corner of the convex portion having a polygonal shape in plan view. The plate making apparatus as described in the item.   The plate making apparatus according to claim 7, wherein the plate making apparatus is set so as to be equal to or lower than an engraving threshold energy over the entire circumference of the convex portion having a polygonal shape in plan view.   The plate making apparatus according to claim 7 or 8, wherein the convex portion has a rectangular shape in plan view. A plate making method for engraving the surface of the recording medium by scanning the recording medium with a light beam at a predetermined pixel pitch,
Lowering the optical power of the light beam for engraving a partial region or the entire region in the adjacent region adjacent to the convex portion leaving the surface of the recording medium in a convex shape so that the upper surface of the convex portion is equal to or lower than the engraving threshold energy;
A plate making method, wherein engraving is performed by raising the optical power of a light beam for engraving an adjacent area close to the outside of the adjacent area.