JP2006095931A - Plate making method and plate making apparatus for printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plate making method and a plate making apparatus for a printing plate, which can reduce plate making time by efficiently using a laser beam. <P>SOLUTION: Engraving is performed through two steps, that are, a precise engraving step of performing the engraving up to a maximum depth dp by a precise engraving beam L1 by irradiating a flexographic sensitized material 10 with a precise engraving pixel pitch pp through the use of the beam L1 with a small beam diameter, and a rough engraving step of performing the engraving up to a relief depth d by irradiating the sensitized material 10 with a rough engraving pixel pitch pc, larger than the pitch pp, through the use of a rough engraving beam L2 with a beam diameter. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  A printing plate making method 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, wherein a laser beam having a first beam diameter is used. And recording at a second pixel pitch using a first engraving step of engraving to a first depth by irradiating a recording material at a first pixel pitch and engraving up to a first depth. And a second engraving step of engraving to a second depth deeper than the first depth by irradiating the material.

  According to a second aspect of the present invention, in the first aspect of the invention, the second beam diameter is not less than the first beam diameter, and the second pixel pitch is not less than the first pixel pitch. It is characterized by.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the printing plate is an intaglio printing plate.

  The invention according to claim 4 is the invention according to claim 1 or 2, wherein the printing plate is a relief printing plate.

  According to a fifth aspect of the present invention, in the printing plate invention of the fourth aspect, the first 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.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the first pixel pitch, the first depth, the sensitivity of the recording material, and the laser light source. The scanning speed of the first engraving process is determined from the power.

  According to a seventh aspect of the present invention, in the first aspect of the present invention, the second pixel pitch, the second depth, the sensitivity of the recording material, and the laser light source The scanning speed of the second engraving process is determined from the power.

  The invention according to claim 8 is a printing plate making apparatus for engraving the 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 laser beam having a first beam diameter by controlling the movement motor, the modulator, the rotation motor, and the movement motor. The recording material is irradiated with the first pixel pitch, engraved to the first depth, and then the laser beam having the second beam diameter is used, and the recording material is applied at the second pixel pitch. And a control unit that performs engraving to the second depth by irradiation.

  The invention according to claim 9 is the invention according to claim 8, further comprising a beam diameter changing mechanism for changing a beam diameter of a laser beam emitted from the recording head, wherein the control unit The beam diameter changing mechanism is controlled so that the beam diameter is larger than the first beam diameter.

  The invention according to claim 10 is the invention according to claim 8 or 9, wherein the printing plate is a relief printing plate.

  According to an eleventh aspect of the present invention, in the tenth aspect of the present invention, the first depth is the engraving depth of the boundary portion between the reliefs when the halftone dot percentages are adjacent to each other. It is.

  According to the inventions of claims 1 to 5 and claims 8 to 11, after engraving to the first depth in the first irradiation step, Since the recess is engraved to a second depth deeper than the depth, the laser beam can be used efficiently, and the plate making time can be shortened.

  According to the invention described in claims 6 and 7, 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. 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.

  An AOM (acousto-optic modulator) 41 is disposed following the laser light source 14. The AOM 41 receives a control signal from the control unit 15 via the AOM driver 42. After the laser beam emitted from the laser light source 14 is modulated by the AOM 41, the variable beam expander 51, the pair of folding mirrors 43 and 44 fixed to the apparatus, the folding mirror 45 fixed to the recording head 12, and the objective lens The flexo sensitive material 10 mounted on the outer peripheral portion of the recording head 12 is irradiated through 46.

  The variable beam expander 51 is for changing the beam diameter of the laser beam irradiated to the flexographic photosensitive material 10 by changing the beam diameter of the laser beam emitted from the laser light source 14. 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 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, 54 at a position facing the emission end of the AOM 41.

  In this laser engraving machine, the laser beam emitted from the laser light source 14 is modulated by the AOM 41, the beam diameter is changed by the variable beam expander 51, and then the folding mirrors 43, 44, 45 and the objective lens 46 are moved. Through the recording head 12. 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.

  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. 2 is an explanatory view schematically showing the shape of the surface of the flexo sensitive material 10 after engraving using this laser engraving machine. 2A is a plan view of seven reliefs formed in the main scanning direction on the flexo sensitive material 10, and FIG. 2B 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 adopted as the engraving pixel pitch at this time, and engraving is performed in minute units as schematically shown in FIG. As the beam diameter of the precision engraving beam L 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 precision engraving beam L2 having a large beam diameter is used. Then, the precision 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. 3 is an explanatory view 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. 3 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. 4 and 5 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 is determined by the following equation (2) based on the precision engraving pixel pitch pp, the maximum depth dp, the engraving sensitivity Y of the flexographic photosensitive material 10, and the power P of the laser light source 14.

pp · dp · v1 · Y = P (2)
Here, the engraving sensitivity 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 power of the laser light source 14 and the irradiation time.

  FIG. 6 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. 6, 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)
4 and 5 again, the 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 v1, the scanning speed v2 is based on the coarse engraving pixel pitch pc, the engraving depth dc, the engraving sensitivity Y of the flexographic photosensitive material 10, and the power P of the laser light source 14 as follows. It is determined by 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. 7 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 slope in a staircase pattern as shown in FIG. 2C 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.

  Next, the moving mechanism 56 is controlled by 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 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 thereby rotate the recording drum 11 and the recording head 12 so that the precision 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, 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. 2 is completed.

Next, engraving times of the conventional plate making method and the plate making method according to the present invention are compared.
[Conventional engraving method]
For example, as shown in FIG. 8, 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). 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 14 is P, the engraving time te is expressed by the following equation.

te = 9.86 · A · d / P
If the engraving area A is 1000000 (mm ² ), the relief depth d is 0.5 (mm), and the power P of the laser light source 14 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. 9, when 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, and the power of the laser light source 14 is P Then, the engraving time t1 is expressed by the following formula.

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 perform rough engraving, as shown in FIG. 10, a precision engraving beam L2 was used, and a recess 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, and the power of the laser light source 14 is P Then, the engraving time t2 is expressed by the following formula.

t1 = 5.18 · A · dc / P
If the engraving area A is 1000000 (mm ² ), the maximum depth dp is 0.3803 (mm), and the power P of the laser light source 14 is 200 (W), the engraving time t2 is approximately 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 embodiment described with reference to FIG. 1, a flexographic material, which is one of the relief printing plates, is used as a recording material. However, an intaglio printing plate such as a gravure plate is recessed by laser engraving on the recording material. The present invention can be applied even when forming.

  In the above embodiment, the laser beam diameter used in the second laser engraving is set to be equal to or larger than the laser beam diameter used in the first engraving. However, the second engraving may be executed with a laser beam having the same diameter as the laser beam used for the first engraving. In this case, at the time of the second engraving, there is a possibility that the flexo sensitive material cannot be scanned at the S / V ratio at which the sensitivity of the flexo sensitive material is the best, and the engraving time is longer than when engraving with the coarse engraving pixel pitch pc. It may take a long time. However, even in this case, it is considered that the engraving time is shortened compared with the case of engraving up to the maximum engraving depth d with one engraving using the precise engraving pixel pitch pp. In addition, since a mechanism for adjusting the laser beam diameter is not necessary, the cost is reduced.

It is a block diagram which shows the outline | summary of a laser engraving machine. 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.

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 Rotating motor 23 Motor driver 24 Encoder 31 Moving motor 32 Ball screw 33 Motor driver 34 Encoder 41 AOM
42 AOM driver 46 Objective lens 51 Variable beam expander 56 Moving mechanism 57 Motor driver 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 (11)

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;
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 using a laser beam having a second beam diameter;
A method for making a printing plate, comprising: In the plate-making method of the printing plate of Claim 1,
The plate making method of a printing plate, wherein the second beam diameter is equal to or greater than the first beam diameter, and the second pixel pitch is equal to or greater than the first pixel pitch. In the plate-making method of the printing plate in any one of Claim 1 or Claim 2,
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 Claim 1 or Claim 2,
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 4,
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 Claims 1 thru | or 5,
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 5,
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;
By controlling the modulator, the rotation motor, and the moving motor, a laser beam having a first beam diameter is used as the first beam diameter, and the recording material is irradiated at a first pixel pitch, A controller that performs engraving to a second depth by irradiating a recording material at a second pixel pitch using a laser beam having a second beam diameter after engraving to the first depth;
An apparatus for making a printing plate, comprising: In the plate-making apparatus of the printing plate of Claim 8,
A beam diameter changing mechanism for changing a beam diameter of a laser beam emitted from the recording head;
The control unit is a printing plate making apparatus that controls the beam diameter changing mechanism so that the second beam diameter is larger than the first beam diameter. In the plate-making apparatus of the printing plate in any one of Claim 8 or Claim 9,
The plate making apparatus for a printing plate, wherein the printing plate is a relief printing plate. In the plate making apparatus according to claim 10,
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.

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