JP2006159800A - Method and equipment for making printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and equipment for making a printing plate which enable reduction of a platemaking time by efficiently using laser beams. <P>SOLUTION: The method for making a printing plate comprises a first engraving process wherein a laser beam L1 having a first beam diameter is used and a flexo sensitized material is irradiated thereby at a first pixel pitch so that engraving is performed to a first depth dp and a second engraving process wherein a laser beam L2 having a second beam diameter larger than the first beam diameter is used and the flexo sensitized material is irradiated thereby at a second pixel pitch larger than the first pixel pitch so that the engraving is performed to a second depth d larger than the first depth. A laser light source is made to oscillate continuously and modulation is conducted by AOM in the first engraving process, while the source is made to oscillate in pulses in the second engraving process. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printing plate making method and a printing plate making apparatus for making a printing plate such as a relief printing plate such as a flexographic printing plate and an intaglio printing plate such as a gravure plate.

Conventionally, for example, a laser engraving machine described in Patent Document 1 is known as such a plate making apparatus. This laser engraving machine scans a recording material with a laser beam emitted from a laser light source to engrave the surface of the recording material to make a relief printing plate. The laser light source and the laser light source A modulator for modulating the laser beam, a recording drum that rotates with a recording material mounted on the outer periphery thereof, and a structure that is movable in a direction parallel to the axis of the recording drum. And a recording head that irradiates a recording material mounted on the unit with a laser beam emitted from a laser light source.
US Pat. No. 5,327,167

  In such a relief printing plate making apparatus, the main scanning speed of the laser beam, that is, the rotational speed of the recording drum, provides the required maximum engraving depth based on the power of the laser light source and the sensitivity of the recording material. Set to a value. In the engraving area shallower than the maximum engraving depth, engraving is executed in a state where the power of the laser beam irradiated to the recording material is reduced.

  At this time, the engraving of the recording material by the laser beam requires a relatively large energy, so that there is a problem that it takes a relatively long time to make the printing plate.

  The present invention has been made to solve the above problems, and provides a printing plate making method and a printing plate making apparatus capable of shortening the plate making time by efficiently using a laser beam. With the goal.

  According to the first aspect of the present invention, there is provided a printing plate for engraving the surface of a recording material and making a printing plate by scanning the recording material with a laser beam emitted from a laser light source and modulated in accordance with an image signal. A first engraving step of engraving to a first depth by irradiating a recording material at a first pixel pitch using a laser beam having a first beam diameter; Using a laser beam having a second beam diameter larger than the beam diameter and irradiating the recording material at a second pixel pitch larger than the first pixel pitch, a second depth deeper than the first depth A second engraving process for engraving until the laser light source is continuously oscillated in the first engraving process, and the laser light source is pulse-oscillated in the second engraving process. To do.

  According to a second aspect of the present invention, in the plate making method of a printing plate, the surface of the recording material is engraved to make a printing plate by scanning the recording material with a laser beam emitted from a laser light source. A first engraving step of engraving to a first depth by irradiating a recording material at a first pixel pitch using a laser beam having a diameter, and a second beam diameter larger than the first beam diameter A second engraving step of engraving to a second depth deeper than the first depth by irradiating a recording material at a second pixel pitch larger than the first pixel pitch using a laser beam having And in the first engraving step, the laser beam is modulated by the modulator, and in the second engraving step, the laser beam is modulated by the laser light source itself.

  According to a third aspect of the present invention, in the plate making method of a printing plate, the surface of the recording material is engraved to make a printing plate by scanning the recording material with a laser beam emitted from a laser light source. A first engraving step of engraving to a first depth by irradiating a recording material at a first pixel pitch using a laser beam having a diameter, and a second beam diameter larger than the first beam diameter A second engraving step of engraving to a second depth deeper than the first depth by irradiating a recording material at a second pixel pitch larger than the first pixel pitch using a laser beam having In the second engraving step, the recording material is preheated to a temperature higher than that in the first engraving step.

  According to a fourth aspect of the present invention, there is provided a printing plate for making a printing plate by engraving a surface of a recording material by scanning the recording material with a laser beam emitted from a laser light source and modulated in accordance with an image signal. In the plate-making method, a first engraving step using a laser beam having a first beam diameter, irradiating a recording material at a first pixel pitch to a first depth, and the first beam diameter Using a laser beam having a smaller second beam diameter, irradiating the recording material with a second pixel pitch smaller than the first pixel pitch, and engraving to a second depth shallower than the first depth A first engraving step for performing the above-mentioned, wherein in the first engraving step, the laser light source is pulsated, and in the second engraving step, the laser light source is continuously oscillated or quasi-continuously oscillated. Features and That.

  According to a fifth aspect of the present invention, in the plate making method of a printing plate, the surface of the recording material is engraved to make a printing plate by scanning the recording material with a laser beam emitted from a laser light source. A first engraving step of engraving to a first depth by irradiating a recording material at a first image pitch using a laser beam having a diameter, and a second beam diameter smaller than the first beam diameter A second engraving step of engraving to a second depth shallower than the first depth by irradiating the recording material with a second image pitch smaller than the first image pitch using a laser beam having In the first engraving step, the laser beam is modulated by the laser itself, and in the second engraving step, the laser beam is modulated by the modulator.

  According to a sixth aspect of the present invention, in the plate making method of a printing plate, the surface of the recording material is engraved to make a printing plate by scanning the recording material with a laser beam emitted from a laser light source. A first engraving step of engraving to a first depth by irradiating a recording material at a first image pitch using a laser beam having a diameter, and a second beam diameter smaller than the first beam diameter A second engraving step of engraving to a second depth shallower than the first depth by irradiating the recording material with a second image pitch smaller than the first image pitch using a laser beam having In the first engraving step, the recording material is preheated to a temperature higher than that in the second engraving step.

  According to a seventh aspect of the present invention, in the plate making method of a printing plate according to any one of the first to third aspects, the printing plate is a relief printing plate.

  According to an eighth aspect of the present invention, in the plate making method of the printing plate according to the seventh aspect, the first depth is a boundary portion of the reliefs when the reliefs whose halftone dot percentages are substantially zero are adjacent to each other. The sculpture depth.

  According to a ninth aspect of the present invention, in the plate making method of a printing plate according to any one of the fourth to sixth aspects, the printing plate is a relief printing plate.

  According to a tenth aspect of the present invention, in the plate making method of the printing plate according to the ninth aspect, the second depth is a boundary portion between the reliefs when the reliefs whose halftone dot percentages are substantially zero are adjacent to each other. The sculpture depth.

  According to an eleventh aspect of the present invention, in the plate making method of a printing plate according to any one of the first to sixth aspects, the printing plate is an intaglio printing plate.

  The invention according to claim 12 is the plate making method of a printing plate according to any one of claims 1 to 11, wherein the first pixel pitch, the first depth, the sensitivity of the recording material, The scanning speed of the first engraving process is determined from the power of the laser light source.

  The invention according to claim 13 is the plate making method of a printing plate according to any one of claims 1 to 11, wherein the second pixel pitch, the second depth, the sensitivity of the recording material, The scanning speed of the second engraving process is determined from the power of the laser light source.

  According to a fourteenth aspect of the present invention, there is provided a printing plate making apparatus for engraving a surface of a recording material to make a printing plate by scanning the recording material with a laser beam emitted from a laser light source. A modulator for modulating the emitted laser beam, a recording drum on which the recording material is mounted, a rotation motor for rotating the recording drum, and a movement parallel to the axis of the recording drum And a recording head that irradiates a recording material mounted on the outer peripheral portion of the recording drum with a laser beam emitted from the laser light source, and the recording head is moved in a direction parallel to the axis of the recording drum. And a beam diameter changing mechanism for changing the beam diameter of the laser beam emitted from the recording head, and the laser light source is oscillated and linked. By controlling the laser light source control unit to oscillate, the modulator, the rotation motor, the moving motor, the beam diameter changing mechanism, and the laser light source control unit, the laser light source is continuously oscillated, Using a laser beam having a first beam diameter, irradiating a recording material at a first pixel pitch, engraving to a first depth, and then oscillating the laser light source in a pulsed state. A laser beam having a second beam diameter greater than the first beam diameter is used to irradiate the recording material at a second pixel pitch greater than the first pixel pitch, and a second deeper than the first depth. And a control unit for engraving to a depth.

  According to a fifteenth aspect of the present invention, there is provided a printing plate making apparatus for engraving a surface of a recording material to make a printing plate by scanning the recording material with a laser beam emitted from a laser light source. A modulator for modulating the emitted laser beam, a recording drum on which the recording material is mounted, a rotation motor for rotating the recording drum, and a movement parallel to the axis of the recording drum And a recording head that irradiates a recording material mounted on the outer peripheral portion of the recording drum with a laser beam emitted from the laser light source, and the recording head is moved in a direction parallel to the axis of the recording drum. Motor, a beam diameter changing mechanism for changing the beam diameter of the laser beam emitted from the recording head, and the modulator can modulate the laser beam A modulator moving mechanism that moves between a modulation position and a retracted position; and the modulator, the rotation motor, the moving motor, the beam diameter changing mechanism, and the modulator moving mechanism to control the modulator Is placed at the modulation position, a laser beam having a first beam diameter is used, and the recording material is irradiated with the laser beam modulated by the modulator at a first pixel pitch to the first depth. After engraving, a laser beam having a second beam diameter larger than the first beam diameter is used with the modulator placed in the retracted position, and the laser beam modulated by the laser light source itself is used. And a controller that performs engraving to a second depth deeper than the first depth by irradiating the recording material at a second pixel pitch larger than the first pixel pitch.

  According to a sixteenth aspect of the present invention, there is provided a printing plate making apparatus for engraving a surface of a recording material to make a printing plate by scanning the recording material with a laser beam emitted from a laser light source. A modulator for modulating the emitted laser beam, a recording drum on which the recording material is mounted, a rotation motor for rotating the recording drum, and a movement parallel to the axis of the recording drum And a recording head that irradiates a recording material mounted on the outer peripheral portion of the recording drum with a laser beam emitted from the laser light source, and the recording head is moved in a direction parallel to the axis of the recording drum. A moving motor, a beam diameter changing mechanism for changing a beam diameter of a laser beam emitted from the recording head, and a recording material mounted on the recording drum A heating mechanism for heating, a laser beam having a first beam diameter is controlled by controlling the modulator, the rotation motor, the moving motor, the beam diameter changing mechanism, and the heating mechanism. The recording material is irradiated at a pixel pitch of 1 mm and engraved to the first depth, and then the recording material is preheated to a higher temperature and has a second beam diameter larger than the first beam diameter. A control unit that uses a laser beam to irradiate a recording material at a second pixel pitch larger than the first pixel pitch and engraves the recording material to a second depth deeper than the first depth. And

  According to a seventeenth aspect of the present invention, there is provided a printing plate making apparatus for engraving a surface of a recording material to make a printing plate by scanning the recording material with a laser beam emitted from a laser light source. A modulator for modulating the emitted laser beam, a recording drum on which the recording material is mounted, a rotation motor for rotating the recording drum, and a movement parallel to the axis of the recording drum And a recording head that irradiates a recording material mounted on the outer peripheral portion of the recording drum with a laser beam emitted from the laser light source, and the recording head is moved in a direction parallel to the axis of the recording drum. And a beam diameter changing mechanism for changing the beam diameter of the laser beam emitted from the recording head, and the laser light source is oscillated and linked. The laser light source control unit to be oscillated, and the modulator, the rotation motor, the moving motor, the beam diameter changing mechanism, and the laser light source control unit are controlled so that the laser light source is oscillated in a pulsed state. After engraving up to a depth of 1, using the laser beam having a second beam diameter smaller than the first pitch in a state where the laser light source is continuously oscillated or quasi-continuously oscillated, the first pixel And a controller that sculpts the recording material at a second pixel pitch smaller than the pitch and performs engraving to a second depth deeper than the first depth.

  The invention described in claim 18 is a printing plate making apparatus for engraving the surface of a recording material and making a printing plate by scanning the recording material with a laser beam emitted from a laser light source. A modulator for modulating the emitted laser beam, a recording drum on which the recording material is mounted, a rotation motor for rotating the recording drum, and a movement parallel to the axis of the recording drum And a recording head that irradiates a recording material mounted on the outer peripheral portion of the recording drum with a laser beam emitted from the laser light source, and the recording head is moved in a direction parallel to the axis of the recording drum. Motor, a beam diameter changing mechanism for changing the beam diameter of the laser beam emitted from the recording head, and the modulator can modulate the laser beam A modulator moving mechanism that moves between a modulation position and a retracted position; and the modulator, the rotation motor, the moving motor, the beam diameter changing mechanism, and the modulator moving mechanism to control the modulator Is placed at the retracted position, a laser beam having a first beam diameter is used, and a recording material is irradiated at a first pixel pitch by a laser beam modulated by the laser light source itself, After engraving to a depth, a laser beam modulated by the modulator using a laser beam having a second beam diameter smaller than the first beam diameter in a state where the modulator is arranged at a modulation position. A control unit that irradiates the recording material at a second pixel pitch smaller than the first pixel pitch and engraves to a second depth deeper than the first depth. .

  According to a nineteenth aspect of the present invention, there is provided a printing plate making apparatus for engraving a surface of a recording material to make a printing plate by scanning the recording material with a laser beam emitted from a laser light source. A modulator for modulating the emitted laser beam, a recording drum on which the recording material is mounted, a rotation motor for rotating the recording drum, and a movement parallel to the axis of the recording drum And a recording head that irradiates a recording material mounted on the outer peripheral portion of the recording drum with a laser beam emitted from the laser light source, and the recording head is moved in a direction parallel to the axis of the recording drum. A moving motor, a beam diameter changing mechanism for changing a beam diameter of a laser beam emitted from the recording head, and a recording material mounted on the recording drum In a state where the recording material is preheated to a high temperature by controlling a heating mechanism for heating, the modulator, the rotation motor, the moving motor, the beam diameter changing mechanism, and the heating mechanism, Using a laser beam having a beam diameter, irradiating the recording material at a first pixel pitch and engraving to a first depth, a lower temperature recording material is smaller than the first beam diameter. A control unit that uses a laser beam having a beam diameter of 2 and irradiates a recording material at a second pixel pitch smaller than the first pixel pitch to engrave to a second depth deeper than the first depth And.

  According to a twentieth aspect of the present invention, in the plate making apparatus for a printing plate according to any one of the fourteenth to sixteenth aspects, the printing plate is a relief printing plate.

  According to a twenty-first aspect of the present invention, in the plate making apparatus according to the twenty-first aspect, the first depth is a depth of engraving at a boundary portion between the reliefs where the halftone dot percentages are adjacent to each other. That's it.

  According to a twenty-second aspect of the present invention, in the plate making apparatus for a printing plate according to any one of the seventeenth to nineteenth aspects, the printing plate is a relief printing plate.

  According to a twenty-third aspect of the present invention, in the plate making apparatus according to the twenty-second aspect, the second depth is the engraving depth of the boundary portion of the reliefs when the reliefs whose dot percentage is substantially zero are adjacent to each other. That's it.

  According to a twenty-fourth aspect of the present invention, in the plate making apparatus for a printing plate according to any one of the fourteenth to nineteenth aspects, the printing plate is an intaglio printing plate.

  According to the invention described in claim 1 and claim 14, in the first engraving process, the laser light source is continuously oscillated to perform precise engraving, and in the second engraving process, the laser light source is pulse-oscillated. Engraving can be performed with a strong laser beam. Therefore, the laser beam can be used efficiently, and the plate making time can be shortened while maintaining high plate making accuracy.

  According to the second and fifteenth aspects of the present invention, in the first engraving process, the laser beam is modulated by the modulator to perform precise engraving, and in the second engraving process, the laser beam is used as the laser light source itself. By modulating with, engraving can be performed with a strong laser beam while preventing loss of light quantity in the modulator. Therefore, the laser beam can be used efficiently, and the plate making time can be shortened while maintaining high plate making accuracy.

  According to the invention described in claim 3 and claim 16, in the first engraving process, precise engraving is performed by preventing thermal expansion, and in the second engraving process, the recording material is transferred from the first engraving process. It becomes possible to perform engraving efficiently by preheating to a higher temperature. Therefore, the laser beam can be used efficiently, and the plate making time can be shortened while maintaining high plate making accuracy.

  According to the invention described in claim 4 and claim 17, in the first engraving process, the laser light source is pulse-oscillated to perform engraving with a strong laser beam, and in the second engraving process, the laser light source is continuously oscillated. And precise engraving becomes possible. Therefore, the laser beam can be used efficiently, and the plate making time can be shortened while maintaining high plate making accuracy.

  According to the invention described in claim 5 and claim 18, by modulating the laser beam with the laser light source itself in the first engraving step, and modulating the laser beam with the modulator in the second engraving step, It is possible to perform engraving with a strong laser beam while preventing loss of light quantity in the modulator. Therefore, the laser beam can be used efficiently, and the plate making time can be shortened while maintaining high plate making accuracy.

  According to the invention described in claim 6 and claim 19, in the first engraving process, the recording material is pre-heated to a temperature higher than that in the second engraving process, and the engraving is performed in the second engraving process. Precise engraving can be performed while preventing thermal expansion. Therefore, the laser beam can be used efficiently, and the plate making time can be shortened while maintaining high plate making accuracy.

  According to the inventions of claims 7 to 10 and claims 20 to 23, it is possible to efficiently make a relief plate.

  According to the invention described in claim 11 and claim 24, it is possible to efficiently make the intaglio.

  According to the invention described in claims 12 and 13, the most efficient scanning speed can be determined, and the plate making time can be minimized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In the following description, first, a precision engraving process in which engraving is performed up to the maximum depth dp by irradiating the flexo sensitive material 10 with a precision engraving pixel pitch pp using the precision engraving beam L1, and a coarse engraving using the coarse beam L2. Explaining the first feature of the present invention that shortens the plate-making time by executing engraving in two steps, the rough engraving step of engraving to the relief depth d by irradiating the flexo sensitive material 10 with the pixel pitch pc, Next, a second feature of the present invention that shortens the plate making time while maintaining high plate making accuracy by using the laser beam efficiently will be described.

  FIG. 1 is a block diagram showing an outline of a laser engraving machine which is a plate making apparatus for a relief printing plate according to the present invention.

  This laser engraving machine includes a recording drum 11 on which a flexo direct photosensitive material (hereinafter referred to as “flexo-sensitive material”) 10 as a recording material for a relief printing plate is mounted on the outer periphery thereof, and an axis of the recording drum 11 The recording head 12 is configured to be movable in a direction parallel to the head, a personal computer 13 serving as an input / output unit and a display unit, a laser light source 14 formed of a gas laser, and a control unit 15 that controls the entire apparatus.

  The recording drum 11 is connected to a rotary motor 21 and rotates around a shaft 22. The rotary motor 21 is connected to a motor driver 23. The motor driver 23 receives a rotational speed command from the control unit 15 and controls the rotation of the rotary motor 21. The rotational speed of the rotary motor 21 and the rotational angular position of the recording drum 11 rotated by the rotary motor 21 are measured by the encoder 24, and the information is transmitted to the control unit 15.

  The recording head 12 can be moved in a direction parallel to the axis of the recording drum 11 by being guided by guide means (not shown). The recording head 12 is installed in parallel with the axis of the recording drum 11, is driven by a ball screw 32 that is rotated by a moving motor 31, and reciprocates in a direction parallel to the axis of the recording drum 11. This moving motor 31 is connected to a motor driver 33. The motor driver 33 receives a rotation speed command from the control unit 15 and controls the rotation of the moving motor 31. The rotational speed of the moving motor 31 and the position of the recording head 12 moved by the moving motor 31 are measured by the encoder 34, and the information is transmitted to the control unit 15.

  FIG. 2 is a schematic diagram showing the recording head 12 together with the recording drum 11.

  In the recording head 12, an objective lens 46 and a preheating mechanism 71 are disposed. The preheating mechanism 71 is for preheating the flexo sensitive material 10 mounted on the outer periphery of the recording drum 11. The preheating mechanism 71 is, for example, for hot air blowing means for blowing hot air toward the flexo sensitive material 10 mounted on the outer peripheral portion of the recording drum 11 or for the recording material 10 mounted on the outer peripheral portion of the recording drum 11. It is composed of a halogen lamp for irradiating infrared rays or induction heating means.

  Referring to FIG. 1 again, an AOM unit 41 having a built-in AOM (acousto-optic modulator) 72 (see FIG. 3) is disposed in the subsequent stage of the laser light source 14. The AOM unit 41 receives an image signal from the control unit 15 via the AOM driver 42 and the switching circuit 65. After the laser beam emitted from the laser light source 14 is modulated by the AOM unit 41, the variable beam expander 51, a pair of folding mirrors 43 and 44 fixed to the apparatus, a folding mirror 45 fixed to the recording head 12, and The light is applied to the flexo sensitive material 10 mounted on the outer periphery of the recording head 12 through the objective lens 46.

  The AOM unit 41 is movable between a modulation position where the laser beam can be modulated and a retracted position by driving a motor 61. The motor 61 is connected to the control unit 15 via a motor driver 62.

  FIG. 3 is a schematic diagram showing the AOM unit 41.

  The AOM unit 41 includes an AOM 72 and a plane parallel plate 73 therein. When the AOM 72 does not modulate the laser beam, the AOM unit 41 is disposed at a retracted position indicated by a solid line in FIG. On the other hand, when it is necessary to perform modulation by the AOM 72, the AOM 72 is moved to the modulation position arranged at the position indicated by the phantom line in FIG. This modulation position is a position where the AOM 72 is arranged in the optical path of the laser beam.

  The plane parallel plate 73 is disposed in the optical path of the laser beam when the AOM unit 41 is disposed at the retracted position. The plane parallel plate 73 is used to cause the laser beam to generate a displacement equivalent to the displacement of the optical path of the laser beam that occurs when the laser beam passes through the AOM 72 when the AOM unit 41 is disposed at the retracted position. is there.

  Referring again to FIG. 1, the variable beam expander 51 changes the beam diameter of the laser beam applied to the flexographic material 10 by changing the beam diameter of the laser beam emitted from the laser light source 14. Is for. The variable beam expander 51 includes three pairs of lenses 52, 53, and 54 that constitute the beam expander, a support member 55 that supports the pair of lenses 52, 53, and 54, and a support member 55 that moves. Thus, a moving mechanism 56 having a motor or the like for disposing any one of the lens pairs 52, 53, 54 at a position facing the emission end of the AOM unit 41 is provided. This moving mechanism 56 is connected to a motor driver 57. The motor driver 57 receives a command from the control unit 15 and arranges the lens pair most suitable for engraving among the lens pairs 52, 53, and 54 at a position facing the emission end of the AOM unit 41.

  The laser light source 14 is connected to the control unit 15 via a driver 63 and a laser light source control unit 64. The laser light source control unit 64 receives an instruction signal for continuous oscillation or pulse oscillation described later from the control unit 15. Further, the laser light source control unit 64 receives an image signal from the control unit 15 via the switching circuit 65. The switching circuit 65 receives from the control unit 15 a switching signal indicating whether an image signal is transmitted to the laser light source control unit 64 or the above-described AOM driver 42.

  In this laser engraving machine, the laser beam emitted from the laser light source 14 is modulated by the AOM 72 in the AOM unit 41, the beam diameter is changed by the variable beam expander 51, and then the folding mirrors 43, 44, 45 and The light is emitted from the recording head 12 through the objective lens 46. Then, in a state where the recording drum 11 having the flexo sensitive material 10 mounted on the outer peripheral portion thereof is rotated, the recording head 12 is moved in a direction parallel to the axis of the recording drum 11, so that the laser beam is placed on the flexo sensitive material 10. Are engraved and a relief is formed on the flexo sensitive material 10. However, when the AOM 72 is not used as will be described later, the laser beam is modulated by the laser light source 14 itself.

  At this time, in this laser engraving machine, the precision engraving beam L1 having a small beam diameter is used, the flexo sensitive material 10 is irradiated with the precision engraving pixel pitch pp, and engraving is performed up to the maximum depth dp with the precision engraving beam L1. Using the precision engraving process to be performed and the coarse beam L2 having a large beam diameter, the flexo sensitive material 10 is irradiated with the coarse engraving pixel pitch pc (equal to the halftone dot pitch) larger than the precise engraving pixel pitch pp, and the relief depth d Engraving is performed by two processes including a rough engraving process for engraving until the plate making time is shortened.

  FIG. 4 is an explanatory view schematically showing the shape of the surface of the flexo sensitive material 10 after engraving using this laser engraving machine. 4A is a plan view of seven reliefs formed in the main scanning direction on the flexo sensitive material 10, and FIG. 4B is a cross-sectional view thereof. In this figure, for the convenience of explanation, seven reliefs having a halftone dot area ratio of 0%, 1%, 1%, 2%, 2%, 0%, and 0% are formed from the left side of the figure. Shows the case.

  As shown in this figure, in the precision engraving process, a precision engraving beam L1 having a small beam diameter is used. Then, this precision engraving beam L1 is irradiated onto the flexo sensitive material 10 at a precise engraving pixel pitch pp, and the flexo sensitive material 10 is engraved from its surface to the maximum depth dp.

  This maximum depth dp coincides with the engraving depth of the boundary portion of these reliefs when the reliefs having very small halftone dot area ratios are adjacent to each other. When the maximum depth dp is smaller than this, it is impossible to express fine halftone dots satisfactorily. Although it is possible to make the maximum depth dp larger than this, the engraving efficiency deteriorates in this case. In this embodiment, when the reliefs having a halftone dot area ratio of 1% are adjacent to each other, the engraving depth of the boundary portion between these reliefs is set to the maximum depth dp.

  In this precision engraving process, engraving of the portion that directly affects the shape of the halftone dots from the surface of the flexo sensitive material 10 to the maximum depth dp is executed. Therefore, a relatively small precision engraving pixel pitch pp is employed as the engraving pixel pitch at this time, and engraving is performed in minute units as schematically shown in FIG. 4C. As the beam diameter of the precision engraving beam L1 at this time, a small beam diameter capable of engraving with the precision engraving pixel pitch pp is employed.

  After the precision engraving process, a rough engraving process is performed. In this rough engraving process, a rough engraving beam L2 having a large beam diameter is used. Then, the rough engraving beam L2 is irradiated onto the flexo sensitive material 10 at the coarse engraving pixel pitch pc, and the flexo sensitive material 10 is engraved from the maximum depth dp to the relief depth d. Thus, since the area engraved by the precision engraving process is engraved again by the coarse engraving process, the engraving depth d from the surface of the flexographic photosensitive material 10 after execution of the coarse engraving process is the engraving depth dp by the precision engraving. Bigger than. In this rough engraving process, the engraving of the portion that does not directly affect the shape of the halftone dots is performed, so that the coarse engraving pixel pitch pc can be increased.

  As the coarse engraving pixel pitch pc at this time, the halftone pitch w can be adopted. The rough engraving pixel pitch pc can be arbitrarily set in the range of the above-described precision engraving pixel pitch pp and the halftone dot pitch w. However, the closer this is to the halftone pitch w, the better the engraving efficiency.

  FIG. 5 is an explanatory diagram showing the relief shape formed on the flexo sensitive material 10 more accurately.

  As parameters representing the relief shape, there are a relief angle θ, a relief depth d, a step dt for forming the top hat portion T, and a plateau wt. The relief angle θ is a value common to all reliefs. The relief depth d is the engraving depth in an area where the halftone dot percentage is zero. Step dt is provided to improve the dot gain, and the plateau wt is provided to increase the mechanical strength of the relief. However, when the top hat portion T itself is not formed, The value of the plateau wt is zero. In the above description, the case where step dt and plateau wt are omitted is described.

  When the relief shape shown in FIG. 4 is adopted, the above-described maximum depth dp can be calculated by the following equation (1).

dp = (2 ^1/2 · pc / 2−wt) tan (θπ / 180) + dt (1)
When the top hat portion T itself is not formed, zero may be substituted for step dt and plateau wt.

  Next, the plate making process of the flexographic printing plate which engraves the flexographic sensitive material 10 using this laser engraving machine will be described. 6 and 7 are flowcharts showing the plate making process.

  When making a flexographic printing plate, the operator first specifies the relief shape and the number of screen lines (step S1). The relief shape and the number of screen lines are input from the personal computer 13 and transmitted to the control unit 15.

  Next, the halftone dot pitch w is determined from the screen line number designated in advance (step S2). This halftone pitch w is the reciprocal of the number of screen lines.

  Next, the maximum depth dp in the precision engraving process is calculated (step S3). This calculation is performed using the above-described equation (1).

  Next, the operator designates the resolution (step S4). This resolution is selected from, for example, 1200 dpi, 2400 dpi, and 4000 dpi.

  Next, the precise engraving pixel pitch pp is determined from the designated resolution (step S5). Note that the width of the precision engraving beam L1 in the sub-scanning direction is adjusted so that the precision engraving pixel pitch pp and the width of the precision engraving beam L1 in the sub-scanning direction substantially coincide with each other.

  Next, the scanning speed v1 at the time of precision engraving is determined (step S6). The scanning speed v1 includes the precision engraving pixel pitch pp, the maximum depth dp, the engraving sensitivity Y of the flexo sensitive material 10, and the power P of the laser beam emitted from the laser light source 14 and irradiated onto the flexo sensitive material 10. Is determined by the following equation (2).

pp · dp · v1 · Y = P (2)
Here, the engraving sensitivity Y is a value obtained by dividing the energy E of the laser beam by the volume V engraved by the laser beam. The energy E of the laser beam is a value obtained by multiplying the irradiation time by the power of the laser beam emitted from the laser light source 14 and irradiated on the flexographic photosensitive material 10.

  FIG. 8 is a graph showing the relationship between the engraving sensitivity Y and the S / V ratio obtained by dividing the surface area of the recess engraved by the laser beam by the volume.

  In this graph, the horizontal axis represents the S / V ratio obtained by dividing the surface area of the recess engraved by the laser beam by the volume, and the vertical axis represents the engraving sensitivity obtained experimentally. As is apparent from this graph, the value of the engraving sensitivity is large (that is, the sensitivity is poor) almost in proportion to S / V. This is presumably because the greater the S / V ratio, the greater the ratio of the heat dissipation to the volume, and the applied energy is not effectively used for engraving. For this reason, in order to execute engraving efficiently, it is effective to use a region having a small S / V ratio.

  In the graph shown in FIG. 8, when the engraving sensitivity is Y and the S / V ratio is X, the following approximate expression (3) is established.

Y = 3.221748 + 0.0577759X (3)
6 and 7 again, next, engraving depth dc in the rough engraving process is calculated (step S7). The engraving depth dc is a value obtained by subtracting the maximum depth dp at the time of precision engraving from the relief depth d.

  Next, the coarse engraving pixel pitch pc for executing the coarse engraving is determined (step S8). The rough engraving pixel pitch pc coincides with the halftone dot pitch w as described above.

  Next, the scanning speed v2 at the time of rough engraving is determined (step S9). As in the case of the scanning speed v 1, the scanning speed v 2 is a coarse engraving pixel pitch pc, an engraving depth dc, an engraving sensitivity Y of the flexo sensitive material 10, and a laser light source 14 that is emitted from the flexo sensitive material 10. Based on the power P of the irradiated laser beam, it is determined by the following equation (4).

pc · dc · v2 · Y = P (4)
Next, relief data indicating the relief shape to be engraved is created from the image data to be formed on the flexo sensitive material 10 (step S10). The basic image data is transferred to the control unit 15 via the personal computer 13 online or offline. Relief data is created based on this image data. This relief data is data obtained by superimposing the data of each relief, and in a region overlapping each other, priority is given to data having a shallower depth.

  FIG. 9 is an explanatory diagram schematically showing a method for creating relief data.

  This figure shows a state in which the relief 1 and the relief 2 are formed. The relief 1 side relief data is used for the area on the relief 1 side from the point where the inclined part of the relief 1 and the relief 2 abuts, and the area on the relief 2 side from the point where the inclined part of the relief 1 and the relief 2 abuts is used. Two relief data are used.

  Next, multivalue data for precision engraving is created from the relief data (step S11). This multi-value data is multi-value data in which engraving up to the maximum depth dp is executed for an area where the dot area ratio is 0%. This multi-value data is created as data that can form a relief inclined portion in a step shape as shown in FIG. 4C in a region where the dot area ratio is 0% to 100%.

  Next, multivalued data for rough engraving is created from the relief data (step S12). This multivalued data is finally engraved with a relief depth d by engraving an area with a halftone dot area ratio of 0% in consideration of the relief angle θ and with an engraving depth dc. Such multivalued data.

  Next, the moving mechanism 56 is controlled under the control of the control unit 15, and the lens pairs 52, 53, and 54 are selected so that the laser beam that has passed through the variable beam expander 51 has the required beam diameter as the precision engraving beam L1. (Step S13). Thus, the width of the precision engraving beam L1 in the sub-scanning direction is adjusted so that the precision engraving pixel pitch pp and the width of the precision engraving beam L1 in the sub-scanning direction are substantially the same.

  Then, precision engraving is executed (step S14). At this time, the control unit 15 controls the motor drivers 23 and 33 to thereby rotate the recording drum 11 and the recording head 12 so that the precision engraving beam L1 scans the flexo sensitive material 10 at the scanning speed v1 described above. Control the moving speed of the. Further, when the control unit 15 controls the AOM driver 42, engraving such as an inclined surface up to the maximum depth dp is executed.

  At the time of this precision engraving, as will be described later, the AOM unit 41 is disposed at the modulation position, and the laser light source 14 continuously oscillates under the control of the laser light source controller 64.

  Next, the moving mechanism 56 is controlled under the control of the control unit 15, and the lens pairs 52, 53, and 54 are selected so that the laser beam that has passed through the variable beam expander 51 has the required beam diameter as the coarse engraving beam L2. (Step S15). As a result, the width of the coarse engraving beam L2 in the sub-scanning direction is adjusted so that the coarse engraving pixel pitch pc and the width of the coarse engraving beam L2 in the sub-scanning direction substantially coincide with each other.

  Then, rough engraving is executed (step S16). At this time, the control unit 15 controls the motor drivers 23 and 33 to rotate the recording drum 11 and the recording head 12 so that the coarse engraving beam L2 scans the flexo sensitive material 10 at the scanning speed v2. Control the moving speed of the. Further, when the control unit 15 controls the AOM driver 42 or the driver 13, engraving such as an inclined surface from the maximum depth dp to the relief depth d is executed. Through the above steps, the relief engraving as shown in FIG. 4 is completed.

  At the time of this rough engraving, as described later, one of the following methods is adopted.

(1) The laser light source 14 is pulse-oscillated and the AOM unit 41 is placed at the retracted position.
(2) The laser light source 14 is pulse-oscillated, and the AOM unit 41 is arranged at the modulation position.
(3) The laser light source 14 is continuously oscillated, and the AOM unit 41 is disposed at the retracted position. At the time of the rough engraving, the flexo sensitive material 10 is preheated by the preheating mechanism 71.

Next, engraving times of the conventional plate making method and the plate making method according to the present invention are compared. However, the following comparison is for the case where the laser light source 14 is continuously oscillated and modulation is performed by the AOM 72 without preheating.
[Conventional engraving method]
For example, as shown in FIG. 10, when a laser beam having the same beam diameter as the precision engraving beam L1 is used and a recess having a width of 21.2 μm and a depth of 500 μm is engraved at a scanning speed L (mm / s), And V are expressed by the following formula, and the S / V ratio is approximately 98.

S = (0.5 × 2 + 0.0212 × 2) · L = 1.0424L
V = 0.5 ・ 0.0212 ・ L = 0.0106 ・ L
And if S / V ratio 98 is input into X of Formula (3) mentioned above, engraving sensitivity Y will be 9.86 (J / mm < ³ >). At this time, assuming that the area of the engraving region is A and the maximum engraving depth (relief depth) is d, the energy required for engraving the entire region is A · d · Y = 9.86 · A · d, and the laser light source If the power of the laser beam emitted from 14 and irradiated onto the flexo sensitive material 10 is P, the engraving time te is expressed by the following equation.

te = 9.86 · A · d / P
When the engraving area A is 1000000 (mm ² ), the relief depth d is 0.5 (mm), and the power P of the laser beam emitted from the laser light source 14 and applied to the flexo sensitive material 10 is 200 (W), The engraving time te is about 6.8 hours.
[Engraving method according to the present invention]
First, in order to execute precision engraving, as shown in FIG. 11, a precision engraving beam L1 is used and a recess having a width of 21.2 μm and a depth of 119.7 μm is engraved at a scanning speed L (mm / s). The S and V are represented by the following formula, and the S / V ratio is approximately 111. The engraving depth of 119.7 μm is calculated from the above-described equation (1).

S = (0.1197 × 2 + 0.0212 × 2) · L = 0.2818L
V = 0.1197 / 0.0212 / L = 0.00053764 / L
When the S / V ratio 111 is input to X in the above-described formula (3), the engraving sensitivity Y is 10.7 (J / mm ³ ). At this time, assuming that the area of the engraving area is A and the maximum depth is dp, the energy required for engraving the entire area is A · dp · Y = 10.7 · A · dp, which is emitted from the laser light source 14. If the power of the laser beam irradiated on the flexo sensitive material 10 is P, the engraving time t1 is expressed by the following equation.

t1 = 10.7 · A · dp / P
If the engraving area A is 1000000 (mm ² ), the maximum depth dp is 0.1197 (mm), and the power P of the laser light source 14 is 200 (W), the engraving time t1 is about 1.7789 hours.

  Next, in order to execute rough engraving, as shown in FIG. 12, a rough engraving beam L2 was used, and a concave portion having a width of 84.7 μm and a depth of 308.3 μm was engraved at a scanning speed L (mm / s). In this case, S and V are expressed by the following formula, and the S / V ratio is approximately 28.9. The engraving depth 308.3 μm is obtained by subtracting the maximum depth dp from the relief depth d, and the engraving width 84.7 μm is determined based on the coarse engraving pixel pitch pc.

S = (0.3803 × 2 + 0.0847 × 2) · L = 0.93L
V = 0.3803 ・ 0.0847 ・ L = 0.032211 ・ L
And if S / V ratio 28.9 is input into X of Formula (3) mentioned above, engraving sensitivity Y will be 5.18 (J / mm < ³ >). At this time, if the area of the engraving area is A and the engraving depth is dc, the energy required for engraving the entire area is A · dc · Y = 5.18 · A · dc, which is emitted from the laser light source 14. If the power of the laser beam irradiated on the flexo sensitive material 10 is P, the engraving time t2 is expressed by the following equation.

t1 = 5.18 · A · dc / P
When the engraving area A is 1000000 (mm ² ), the maximum depth dp is 0.3803 (mm), and the power P of the laser beam emitted from the laser light source 14 and applied to the flexo sensitive material 10 is 200 (W), The engraving time t2 is about 2.7361 hours.

  The engraving time t obtained by adding the precision engraving time t1 and the rough engraving time t2 is 4.515 hours. This engraving time t is much shorter than the conventional engraving time te (6.8 hours).

  In the above-described embodiment, the flexographic photosensitive material, which is one of the relief printing plates, is used as the recording material. However, even when an intaglio printing plate such as a gravure plate is formed by recessing the recording material by laser engraving, The invention is applicable.

  FIG. 13 is an explanatory view schematically showing the shape of the intaglio printing plate in such an embodiment.

  As shown in this figure, even when the intaglio printing plate is made, the precision engraving beam L1 having a small beam diameter is used in the precision engraving process. Then, the intaglio printing plate is irradiated with the precision engraving beam L1 at the precision engraving pixel pitch pp, and the intaglio printing plate is engraved from the surface to the depth dp.

  In the coarse engraving process, a coarse engraving beam L2 having a large beam diameter is used. Then, the rough engraving beam L2 is irradiated onto the intaglio printing plate at the rough engraving pixel pitch pc to engrave the intaglio printing plate from the depth dp to the depth d. Thus, since the area engraved by the precision engraving process is engraved again by the rough engraving process, the engraving depth d from the surface of the intaglio printing plate after execution of the coarse engraving process is greater than the engraving depth dp by the precision engraving. Is also big. In this rough engraving process, the engraving of the portion that does not directly affect the shape of the cell is performed, so that the coarse engraving pixel pitch pc can be increased.

  Next, a second feature of the present invention that shortens the plate-making time while maintaining high plate-making accuracy by efficiently using a laser light source will be described.

  First, the waveform of the laser light source 14 will be examined.

  A general laser light source can switch between continuous oscillation and pulse oscillation. The peak power during pulse oscillation is larger than the peak power during continuous oscillation. For example, in the case of a carbon dioxide laser, the peak power at the time of pulse oscillation is several times to 10 times the peak power at the time of continuous oscillation, and in the case of a YAG laser, the peak power at the time of pulse oscillation is at the time of continuous oscillation. It is about 100 times the peak power. When the printing plate is engraved, the larger the peak power, the more efficiently engraving can be achieved by preventing heat dissipation.

  On the other hand, the maximum frequency during pulse oscillation is about 100 kHz. This frequency is sufficient for the rough engraving process described above, but is insufficient to perform the precision engraving process. Therefore, engraving is performed by oscillating the laser light source 14 in the rough engraving process, and engraving is performed in the precision engraving process by continuously oscillating the laser light source 14 and modulating the laser beam by another modulator. As a result, the laser beam can be used efficiently, and the plate-making time can be shortened while maintaining high plate-making accuracy.

  Next, the presence or absence of a modulator will be examined.

  For example, the AOM 72 can perform high-speed modulation of about 1 MHz, but germanium used for the AOM 72 has a low laser beam transmittance, and the laser beam causes a loss of about several percent in the AOM 72. For this reason, if the laser beam is modulated by the laser light source 14 itself in the rough engraving process and engraving is performed by the modulator in the precision engraving process, the laser beam can be used efficiently. It is possible to shorten the plate making time while maintaining high plate making accuracy.

  The laser light source 14 may be quasi-continuously oscillated when the precision engraving process is executed. Then, the laser beam emitted from the laser light source 14 is modulated by the AOM 72.

The following methods can be considered as a method of causing the laser light source 14 to oscillate continuously in a pseudo manner.
For example, when a high-frequency drive signal exceeding the response speed is supplied from the driver 63 to the laser light source 14, the laser light source 14 emits a laser beam that appears to be continuous but apparently continuous. Alternatively, when a high duty drive signal is supplied from the driver 63 to the laser light source 14, the laser light source 14 oscillates in a pulse but emits an apparently continuous laser beam. In this way, while the laser light source 14 is oscillated continuously in a pseudo manner, an image signal is supplied from the switching circuit 65 to the AOM driver 42 to modulate the laser beam, and the flexo sensitive material 10 is subjected to precision engraving.

  Next, preheating will be examined.

  For example, when the flexo sensitive material 10 is used, it is known that if the flexo sensitive material 10 is heated to about 100 degrees Celsius in advance, the processing efficiency by the laser beam is improved by about 30%. For this reason, if such preheating is performed, engraving can be performed efficiently. However, when preheating is performed, the flexo sensitive material 10 is thermally expanded and its dimensional accuracy is deteriorated. In addition, when the heating temperature is uneven, the relief depth varies. Therefore, pre-heating is performed in the rough engraving process and engraving is performed. In the precision engraving process, pre-heating is not performed, or pre-heating is performed at a lower temperature than the rough engraving process. It is possible to shorten the plate making time while maintaining the plate making accuracy.

  Based on the premise as described above, an embodiment of the plate making process for the flexo sensitive material 10 shown in FIG. 4 will be described.

  First, the precision engraving process will be described. FIG. 14 is an explanatory diagram showing a recording beam and the like in the precision engraving process.

  In the precision engraving process, as described above, since the engraving depth is relatively shallow, the scanning speed is fast and the pixel pitch is fine, so it is necessary to increase the modulation frequency. For this reason, in the precision engraving process, the AOM unit 41 is arranged at the modulation position. Further, the laser light source 14 is continuously oscillated or quasi-continuously oscillated under the control of the laser light source controller 64. Further, an image signal is input to the AOM driver 42 by the switching circuit 65. In this case, as shown in FIG. 14, it is possible to form a recording beam by modulating a continuously oscillating laser beam with a modulation signal whose modulation efficiency by the AOM 72 is changed. In the precision engraving process, preheating is not performed in order to obtain high engraving accuracy.

  Next, a first embodiment of the rough engraving process will be described. FIG. 15 is an explanatory diagram showing a recording beam in the rough engraving process according to the first embodiment.

  In the rough engraving process, the scanning speed is slow because the engraving depth is deep, and the modulation speed may be relatively slow because the pixel pitch is coarse. For this reason, in the rough engraving process according to the first embodiment, the AOM unit 41 is moved to the retracted position. Further, the laser light source 14 is oscillated in pulses by the control of the laser light source control unit 64. In addition, an image signal is input to the laser light source controller 64 by the switching circuit 65. Further, the flexo sensitive material 10 is preheated by the preheating mechanism 71. In this case, as shown in FIG. 15, the laser beam is modulated by the laser light source 14 itself. By doing so, the laser light source 14 emits a pulsed laser beam having a high peak power. Then, since the laser beam is modulated by the laser light source 14 itself, no light loss of the laser beam by the AOM 72 occurs. Furthermore, since the flexo sensitive material 10 is preheated, engraving is performed efficiently. Therefore, it is possible to shorten the plate making time.

  Next, a second embodiment of the rough engraving process will be described. FIG. 16 is an explanatory diagram showing a recording beam and the like in the rough engraving process according to the second embodiment.

  In the rough engraving process according to the second embodiment, the AOM unit 41 is moved to the modulation position. Further, the laser light source 14 is pulse-oscillated with a constant intensity under the control of the laser light source controller 64. In addition, an image signal is input to the AOM driver 42 by the switching circuit 65. Further, the flexo sensitive material 10 is preheated by the preheating mechanism 71. In this case, as shown in FIG. 16, it is possible to form a recording beam by modulating a laser beam pulse-oscillated with a constant output by a modulation signal in which the modulation efficiency by the AOM 72 is changed. In this case, the laser light source 14 emits a pulsed laser beam having a high peak power. Furthermore, since the flexo sensitive material 10 is preheated, engraving is performed efficiently. Therefore, it is possible to shorten the plate making time. Further, since modulation is performed using the modulation signal of AOM 72, accurate modulation is possible.

  Next, a third embodiment of the rough engraving process will be described. FIG. 17 is an explanatory diagram showing a recording beam in the rough engraving process according to the third embodiment.

  In the rough engraving process according to the third embodiment, the AOM unit 41 is moved to the retracted position. Further, the laser light source 14 is continuously oscillated under the control of the laser light source control unit 64. In addition, an image signal is input to the laser light source controller 64 by the switching circuit 65. Further, the flexo sensitive material 10 is preheated by the preheating mechanism 71. In this case, as shown in FIG. 17, the laser beam is modulated by the laser light source 14 itself. In this case, the peak power of the laser beam from the laser light source 14 is small, but since the laser beam is modulated by the laser light source 14 itself, no light loss of the laser beam by the AOM 72 occurs. Furthermore, since the flexo sensitive material 10 is preheated, engraving is performed efficiently. Therefore, it is possible to shorten the plate making time.

  In the embodiment described above, preheating is stopped in the precision engraving process in order to obtain high engraving accuracy. However, in the precision engraving process, engraving may be performed efficiently while maintaining the required accuracy by performing preheating at a lower temperature than in the rough engraving process.

  However, preheating is not necessarily required in the rough engraving process.

  In the embodiment described above, the AOM 72 is moved to the retracted position so that the AOM 72 is not positioned on the optical path of the laser light emitted from the laser light source 14. However, by setting an appropriate detour optical path without moving the AOM 72 itself, the laser light emitted from the laser light source 14 does not pass through the AOM 72 and any of the lens pairs 52, 53, 54 of the variable beam expander 51. You may make it inject into such a lens pair.

  Further, in the above-described embodiment, the engraving on the sheet-like recording material wound around the recording drum 11 has been described as an example. However, the surface of the recording material is rotated while rotating a cylindrical recording material such as a gravure cylinder. Alternatively, engraving may be performed directly according to the image signal.

  In the above-described embodiment, the laser beam emitted in the precision engraving process has a small beam diameter as the first beam diameter, and the first engraving pixel pitch pp as the first pixel pitch is the first. For engraving up to the maximum depth dp as the depth, the laser beam emitted in the coarse engraving process has a large beam diameter as the second beam diameter, and the coarse engraving as the second pixel pitch This is for engraving with the pixel pitch pc to the relief depth d as the second depth.

  Further, in the above-described embodiment, rough engraving is performed after precision engraving. However, the order of engraving is not limited to this. The rough engraving may be performed first and then the fine engraving may be performed. Even in this case, the scanning time can be shortened compared with the case where image recording is performed only by precision engraving. This will be described with reference to FIG.

  FIG. 18 is an explanatory view for schematically explaining the shape of the surface of the flexo sensitive material 10 similar to that described above with reference to FIG. 18A is a plan view of seven reliefs formed in the main scanning direction on the flexo sensitive material 10, and FIG. 18B is a diagram after rough engraving is performed on the flexo sensitive material 10. FIG. 18C is a cross-sectional view after further precision engraving is performed on the flexo sensitive material 10 after rough engraving. In FIG. 18, for the convenience of explanation, seven reliefs having a dot area ratio of 0%, 1%, 1%, 2%, 2%, 0%, and 0% are formed from the left side of the drawing. Shows the case.

  As shown in FIG. 18B, in the coarse engraving process, engraving is performed on an area other than the area to be engraved only by precision engraving (that is, the area that directly affects the dot shape). That is, the hatched region in the figure is removed by irradiating the flexo sensitive material 10 with the coarse engraving beam L2 at the coarse engraving pixel pitch pc (equal to the halftone dot pitch). Thereby, an inclined surface or the like that does not directly affect the halftone dot shape of each relief is formed.

  The maximum engraving depth ddc executed at this stage is substantially equal to the engraving depth dc described above with reference to FIG.

  Further, in this coarse engraving process, engraving of a portion that does not directly affect the shape of the halftone dots is performed, so that the coarse engraving pixel pitch pc can be increased.

When performing this rough engraving, as described above, one of the following methods is adopted.
(1) The laser light source 14 is pulsated and the AOM unit 41 is disposed at the retracted position. (2) The laser light source 14 is pulsated and the AOM unit 41 is disposed at the modulation position. (3) The laser light source 14 is continuously oscillated. The AOM unit 41 is disposed at the retracted position. At the time of rough engraving, the flexo sensitive material 10 is preheated by the residual heat heating mechanism 71.

  When the rough engraving process is completed, the precision engraving is then performed by irradiating the flexo sensitive material 10 with the precision engraving beam L1 at a precision engraving pixel pitch pp smaller than the coarse engraving pixel pitch pc. At this stage, as shown in FIG. 18 (c), an area that directly affects the halftone dot shape (hatched area a) and an area that does not affect the halftone dot shape depending on the previous rough engraving. Engraving is performed on an area that has not reached the desired relief depth d (hatched area b). Thus, since the area engraved in the coarse engraving process is engraved again by precision engraving, the engraving depth d from the surface of the flexo sensitive material after execution of the precision engraving process is larger than the engraving depth ddc by coarse engraving. . Further, the engraving depth ddp of the region b in the precision engraving process is substantially equal to the maximum engraving depth dp. As described above, the laser light source 14 is continuously oscillated or pseudo-continuously oscillated in precision engraving.

  Thus, even when precise engraving is performed after rough engraving, an appropriate relief shape can be formed. In this case, the laser beam emitted in the coarse engraving process has a large beam diameter as the first beam diameter, and the relief depth as the first depth at the coarse engraving pixel pitch pc as the first pixel pitch. The laser beam emitted in the precision engraving process has a small beam diameter as the second beam diameter, and has a precision engraving pixel pitch pp as the second pixel pitch. This is for engraving up to the maximum depth dp as the second depth.

It is a block diagram which shows the outline | summary of a laser engraving machine. 3 is a schematic diagram showing the recording head 12 together with the recording drum 11. FIG. 4 is a schematic diagram showing an AOM unit 41. FIG. It is explanatory drawing which shows the shape of the flexo sensitive material 10 surface typically. It is explanatory drawing which shows a relief shape. It is a flowchart which shows a plate making process. It is a flowchart which shows a plate making process. It is a graph which shows the relationship between the engraving sensitivity Y and the S / V ratio of the recessed part processed with the laser beam. It is explanatory drawing which shows the production method of relief data typically. It is a schematic diagram which shows the engraving state by the conventional engraving method. It is a schematic diagram which shows the engraving state by the engraving method which concerns on this invention. It is a schematic diagram which shows the engraving state by the engraving method which concerns on this invention. It is explanatory drawing which shows the shape of an intaglio printing plate typically. It is explanatory drawing which shows the recording beam etc. in a precision engraving process. It is explanatory drawing which shows the recording beam in the rough engraving process which concerns on 1st Embodiment. It is explanatory drawing which shows the recording beam etc. in the rough engraving process based on 2nd Embodiment. It is explanatory drawing which shows the recording beam in the rough engraving process which concerns on 3rd Embodiment. It is explanatory drawing which shows the shape of a flexo sensitive material surface typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Flexo sensitive material 11 Recording drum 12 Recording head 13 Personal computer 14 Laser light source 15 Control part 21 Rotation motor 23 Motor driver 24 Encoder 31 Moving motor 32 Ball screw 33 Motor driver 34 Encoder 41 AOM unit 42 AOM driver 46 Objective lens 51 Variable type Beam expander 56 Movement mechanism 57 Motor driver 61 Motor 62 Motor driver 63 Driver 64 Laser light source controller 65 Switching circuit 71 Preheating mechanism 72 AOM
73 Parallel plane plate L1 Precision engraving beam L2 Coarse engraving beam d Relief depth dp Maximum depth dc Engraving depth pp Precision engraving pixel pitch pc Coarse engraving pixel pitch

Claims (24)

In a plate making method of a printing plate for engraving the surface of a recording material and making a printing plate by scanning the recording material with a laser beam emitted from a laser light source and modulated in accordance with an image signal,
A first engraving step of engraving to a first depth by irradiating a recording material at a first pixel pitch using a laser beam having a first beam diameter;
Using a laser beam having a second beam diameter larger than the first beam diameter and irradiating a recording material at a second pixel pitch larger than the first pixel pitch, the depth is deeper than the first depth. A second engraving process for engraving to a second depth,
In the first engraving step, the laser light source is continuously oscillated or pseudo-continuously oscillated,
In the second engraving step, a method for making a printing plate, wherein the laser light source is pulse-oscillated. In the plate making method of a printing plate for making a printing plate by engraving the surface of the recording material by scanning the recording material with a laser beam emitted from a laser light source,
A first engraving step of engraving to a first depth by irradiating a recording material at a first pixel pitch using a laser beam having a first beam diameter;
Using a laser beam having a second beam diameter larger than the first beam diameter and irradiating a recording material at a second pixel pitch larger than the first pixel pitch, the depth is deeper than the first depth. A second engraving process for engraving to a second depth,
In the first engraving step, a laser beam is modulated by the modulator,
In the second engraving step, a printing plate making method, wherein a laser beam is modulated by the laser light source itself. In the plate making method of a printing plate for making a printing plate by engraving the surface of the recording material by scanning the recording material with a laser beam emitted from a laser light source,
A first engraving step of engraving to a first depth by irradiating a recording material at a first pixel pitch using a laser beam having a first beam diameter;
Using a laser beam having a second beam diameter larger than the first beam diameter and irradiating a recording material at a second pixel pitch larger than the first pixel pitch, the depth is deeper than the first depth. A second engraving process for engraving to a second depth,
In the second engraving step, the recording material is preheated to a temperature higher than that of the first engraving step, and a printing plate making method is characterized. In a plate making method of a printing plate for engraving the surface of a recording material and making a printing plate by scanning the recording material with a laser beam emitted from a laser light source and modulated in accordance with an image signal,
A first engraving process using a laser beam having a first beam diameter and irradiating a recording material at a first pixel pitch to a first depth;
Using a laser beam having a second beam diameter smaller than the first beam diameter and irradiating a recording material at a second pixel pitch smaller than the first pixel pitch, the recording material is shallower than the first depth. A first engraving process for engraving to a second depth,
In the first engraving step, the laser light source is pulsated,
In the second engraving step, a method for making a printing plate, wherein the laser light source is continuously oscillated or pseudo-continuously oscillated. In the plate making method of a printing plate for making a printing plate by engraving the surface of the recording material by scanning the recording material with a laser beam emitted from a laser light source,
A first engraving step of engraving to a first depth using a laser beam having a first beam diameter and irradiating a recording material at a first image pitch;
A laser beam having a second beam diameter smaller than the first beam diameter is used, and the recording material is irradiated with a second image pitch smaller than the first image pitch, and is shallower than the first depth. A second engraving process for engraving to a second depth,
In the first engraving process, a laser beam is modulated by the laser itself,
In the second engraving step, a printing plate making method, wherein a laser beam is modulated by the modulator. In the plate making method of a printing plate for making a printing plate by engraving the surface of the recording material by scanning the recording material with a laser beam emitted from a laser light source,
A first engraving step of engraving to a first depth using a laser beam having a first beam diameter and irradiating a recording material at a first image pitch;
A laser beam having a second beam diameter smaller than the first beam diameter is used, and the recording material is irradiated with a second image pitch smaller than the first image pitch, and is shallower than the first depth. A second engraving process for engraving to a second depth,
In the first engraving step, the recording material is pre-heated to a temperature higher than that in the second engraving step, and a printing plate making method is characterized. In the plate-making method of the printing plate in any one of Claim 1 thru | or 3,
The plate making method of a printing plate, wherein the printing plate is a relief printing plate. In the plate-making method of the printing plate of Claim 7,
The printing plate making method of the printing plate, wherein the first depth is a sculpture depth of a boundary portion between reliefs having halftone dot percentages of substantially zero adjacent to each other. In the plate-making method of the printing plate in any one of Claim 4 thru | or 6,
The plate making method of a printing plate, wherein the printing plate is a relief printing plate. In the plate-making method of the printing plate of Claim 9,
The plate making method of a printing plate, wherein the second depth is a sculpture depth of a boundary portion between the reliefs having halftone dot percentages of approximately zero adjacent to each other. In the plate-making method of the printing plate in any one of Claims 1 thru | or 6,
A method for making a printing plate, wherein the printing plate is an intaglio printing plate. In the plate-making method of the printing plate in any one of Claims 1 thru | or 11,
A printing plate making method for determining a scanning speed of the first engraving process from the first pixel pitch, the first depth, the sensitivity of a recording material, and the power of the laser light source. In the plate-making method of the printing plate in any one of Claims 1 thru | or 11,
A printing plate making method for determining a scanning speed of the second engraving step from the second pixel pitch, the second depth, the sensitivity of a recording material, and the power of the laser light source. In a plate making apparatus for a printing plate for engraving the surface of the recording material and making a printing plate by scanning the recording material with a laser beam emitted from a laser light source,
A modulator for modulating a laser beam emitted from the laser light source;
A recording drum for mounting a recording material on the outer periphery,
A rotation motor for rotating the recording drum;
A recording head configured to be movable in a direction parallel to the axis of the recording drum and irradiating a recording material mounted on an outer peripheral portion of the recording drum with a laser beam emitted from the laser light source;
A moving motor for moving the recording head in a direction parallel to the axis of the recording drum;
A beam diameter changing mechanism for changing a beam diameter of a laser beam emitted from the recording head;
A laser light source controller for causing the laser light source to oscillate and continuously oscillate;
By controlling the modulator, the rotation motor, the moving motor, the beam diameter changing mechanism, and the laser light source control unit, the first beam is oscillated continuously or pseudo-continuously. A laser beam having a diameter, irradiating a recording material at a first pixel pitch, engraving to a first depth, and then pulsing the laser light source, Using a laser beam having a larger second beam diameter, irradiating the recording material at a second pixel pitch larger than the first pixel pitch, and engraving to a second depth deeper than the first depth A control unit to perform,
An apparatus for making a printing plate, comprising: In a plate making apparatus for a printing plate for engraving the surface of the recording material and making a printing plate by scanning the recording material with a laser beam emitted from a laser light source,
A modulator for modulating a laser beam emitted from the laser light source;
A recording drum for mounting a recording material on the outer periphery,
A rotation motor for rotating the recording drum;
A recording head configured to be movable in a direction parallel to the axis of the recording drum and irradiating a recording material mounted on an outer peripheral portion of the recording drum with a laser beam emitted from the laser light source;
A moving motor for moving the recording head in a direction parallel to the axis of the recording drum;
A beam diameter changing mechanism for changing a beam diameter of a laser beam emitted from the recording head;
A modulator moving mechanism for moving the modulator between a modulation position where the laser beam can be modulated and a retracted position;
By controlling the modulator, the rotation motor, the moving motor, the beam diameter changing mechanism, and the modulator moving mechanism, the modulator has the first beam diameter in a state of being arranged at a modulation position. Using a laser beam, irradiating a recording material with a first pixel pitch with a laser beam modulated by the modulator, engraving to a first depth, and then placing the modulator in a retracted position A recording material using a laser beam having a second beam diameter larger than the first beam diameter and having a second pixel pitch larger than the first pixel pitch by a laser beam modulated by the laser light source itself. And a controller that performs engraving to a second depth deeper than the first depth;
An apparatus for making a printing plate, comprising: In a plate making apparatus for a printing plate for engraving the surface of the recording material and making a printing plate by scanning the recording material with a laser beam emitted from a laser light source,
A modulator for modulating a laser beam emitted from the laser light source;
A recording drum for mounting a recording material on the outer periphery,
A rotation motor for rotating the recording drum;
A recording head configured to be movable in a direction parallel to the axis of the recording drum and irradiating a recording material mounted on an outer peripheral portion of the recording drum with a laser beam emitted from the laser light source;
A moving motor for moving the recording head in a direction parallel to the axis of the recording drum;
A beam diameter changing mechanism for changing a beam diameter of a laser beam emitted from the recording head;
A heating mechanism for heating the recording material mounted on the recording drum;
By controlling the modulator, the rotation motor, the moving motor, the beam diameter changing mechanism, and the heating mechanism, a laser beam having a first beam diameter is used, and a recording material is recorded at a first pixel pitch. , Engraving to the first depth, and using a laser beam having a second beam diameter larger than the first beam diameter in a state in which the recording material is preheated to a higher temperature, A controller that sculpts the recording material at a second pixel pitch that is larger than the first pixel pitch and engraves to a second depth that is deeper than the first depth; and
An apparatus for making a printing plate, comprising: In a plate making apparatus for a printing plate for engraving the surface of the recording material and making a printing plate by scanning the recording material with a laser beam emitted from a laser light source,
A modulator for modulating a laser beam emitted from the laser light source;
A recording drum for mounting a recording material on the outer periphery,
A rotation motor for rotating the recording drum;
A recording head configured to be movable in a direction parallel to the axis of the recording drum and irradiating a recording material mounted on an outer peripheral portion of the recording drum with a laser beam emitted from the laser light source;
A moving motor for moving the recording head in a direction parallel to the axis of the recording drum;
A beam diameter changing mechanism for changing a beam diameter of a laser beam emitted from the recording head;
A laser light source controller for causing the laser light source to oscillate and continuously oscillate;
Engraving was performed up to a first depth in a state where the laser light source was pulsated by controlling the modulator, the rotation motor, the moving motor, the beam diameter changing mechanism, and the laser light source control unit. Thereafter, in a state where the laser light source is continuously oscillated or quasi-continuously oscillated, a laser beam having a second beam diameter smaller than the first pitch is used, and a second pixel pitch smaller than the first pixel pitch. A control unit that irradiates the recording material with a sculpture to a second depth deeper than the first depth;
An apparatus for making a printing plate, comprising: In a plate making apparatus for a printing plate for engraving the surface of the recording material and making a printing plate by scanning the recording material with a laser beam emitted from a laser light source,
A modulator for modulating a laser beam emitted from the laser light source;
A recording drum for mounting a recording material on the outer periphery,
A rotation motor for rotating the recording drum;
A recording head configured to be movable in a direction parallel to the axis of the recording drum and irradiating a recording material mounted on an outer peripheral portion of the recording drum with a laser beam emitted from the laser light source;
A moving motor for moving the recording head in a direction parallel to the axis of the recording drum;
A beam diameter changing mechanism for changing a beam diameter of a laser beam emitted from the recording head, a modulator moving mechanism for moving the modulator between a modulation position where the laser beam can be modulated and a retracted position;
By controlling the modulator, the rotation motor, the moving motor, the beam diameter changing mechanism, and the modulator moving mechanism, the first beam diameter is set in a state where the modulator is disposed at the retracted position. The recording material is irradiated with a recording material at a first pixel pitch by a laser beam modulated by the laser light source itself, engraving to a first depth, and then the modulator is arranged at a modulation position. In this state, a laser beam having a second beam diameter smaller than the first beam diameter is used, and recording is performed at a second pixel pitch smaller than the first pixel pitch by the laser beam modulated by the modulator. A controller that irradiates the material and engraves to a second depth deeper than the first depth;
An apparatus for making a printing plate, comprising: In a plate making apparatus for a printing plate for engraving the surface of the recording material and making a printing plate by scanning the recording material with a laser beam emitted from a laser light source,
A modulator for modulating a laser beam emitted from the laser light source;
A recording drum for mounting a recording material on the outer periphery,
A rotation motor for rotating the recording drum;
A recording head configured to be movable in a direction parallel to the axis of the recording drum and irradiating a recording material mounted on an outer peripheral portion of the recording drum with a laser beam emitted from the laser light source;
A moving motor for moving the recording head in a direction parallel to the axis of the recording drum;
A beam diameter changing mechanism for changing a beam diameter of a laser beam emitted from the recording head;
A heating mechanism for heating the recording material mounted on the recording drum;
A laser beam having a first beam diameter in a state in which the recording material is preheated to a high temperature by controlling the modulator, the rotation motor, the moving motor, the beam diameter changing mechanism, and the heating mechanism. And sculpting to a first depth by irradiating the recording material at a first pixel pitch and then having a second beam diameter smaller than the first beam diameter for a lower temperature recording material A control unit that uses a laser beam to irradiate a recording material at a second pixel pitch smaller than the first pixel pitch, and engraves to a second depth deeper than the first depth;
An apparatus for making a printing plate, comprising: The plate making apparatus for a printing plate according to any one of claims 14 to 16,
The plate making apparatus for a printing plate, wherein the printing plate is a relief printing plate. The plate making apparatus according to claim 20,
The plate making apparatus for a printing plate, wherein the first depth is a sculpture depth of a boundary portion between reliefs having halftone dot percentages of substantially zero adjacent to each other. In the plate-making apparatus of the printing plate in any one of Claim 17 thru | or 19,
The plate making apparatus for a printing plate, wherein the printing plate is a relief printing plate. The plate making apparatus according to claim 22,
The plate making apparatus for a printing plate, wherein the second depth is a sculpture depth of a boundary portion between the reliefs having halftone dot percentages of approximately zero adjacent to each other. In the plate-making apparatus of the printing plate in any one of Claim 14 thru | or 19,
The plate making apparatus for a printing plate, wherein the printing plate is an intaglio printing plate.

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