JPH06234087A - Laser plate making device - Google Patents

Abstract

PURPOSE:To maintain the spacing between a plate sheet surface and an objective lens at a specified value with simple constitution. CONSTITUTION:The plate sheet 14 is irradiated with a laser beam L while a revolving roller 78 is pressed to the plate sheet 14 by a compression spring 84 at the time of providing the revolving roller 78 integrally mounted to a laser block 26 and forming recesses 15 on the plate sheet 14. The revolving roller 78 is, therefore, eventually moved in the forward and backward directions (arrow H, I directions) of the plate sheet 14 in compliance with the surface of the plate sheet 14 and, therefore, the specified spacing d between the objective lens 12 and the plate sheet 14 is obtd. at all times if the spacing d is once so adjusted that the focus of the laser beam L is matched with the surface of the plate sheet 14. The surface of the plate sheet 14 is thus irradiated with the laser beam L having the specified laser power meeting the focus. The recesses 15 of the same depth are, therefore, formed on the plate sheet 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser plate making apparatus for forming a printing plate for a gravure printing machine, for example.

[0002]

2. Description of the Related Art Conventionally, in a laser plate making apparatus, a plate block wound around a rotating plate cylinder is irradiated with a laser beam from a laser block to form a recess corresponding to image information on the plate sheet. It is like this.

In this case, an objective lens is arranged in the laser block so that the laser beam is focused on the surface of the plate sheet.

FIG. 4A shows a partial plan view of such a laser plate making apparatus. FIG. 4B shows the side structure.

In FIGS. 4A and 4B, a moving table 6 which moves in the directions of arrows A and B is arranged on the guide rails 2 and 4 arranged in parallel.

On the moving table 6, a laser block mounting base 8 is arranged. The mount 8 is integrally attached to the arm 10. A laser block 9 is integrally mounted on the mount 8. An objective lens 12 is attached to the tip of the laser block 9, and the laser beam L passes through the objective lens 12.
Is irradiated on the plate sheet 14.

The plate sheet 14 is wound around the plate cylinder 5 and rotated in the direction of arrow E.

Accordingly, the laser beam L is applied to the plate sheet 14 rotated in the direction of arrow E (direction opposite to the main scanning direction), and the laser block 9 moves on the guide rails 2 and 4 in the direction of arrow A ( By being moved in the sub-scanning direction), a depression 15 corresponding to image information is formed on the entire surface of the plate sheet 14.
Can be formed.

Since the depth of the recess 15 formed in this way corresponds to the gradation at the time of gravure printing, it is necessary to maintain a constant depth at a constant gradation.

In order to maintain a constant depth, it is necessary to maintain a constant distance (distance) d between the objective lens 12 and the surface of the plate sheet 14.

Therefore, in the laser plate making apparatus according to the prior art shown in FIG. 4, the plate cylinder 5 is manufactured as accurately as possible to reduce the eccentricity of the plate cylinder 5 and the lateral feed direction of the laser block 9. The direction (arrows A and B directions) and the line parallel to the axis of the circumferential surface of the plate cylinder 5 (direction of movement of the laser block 9 in the directions A and B) are made as parallel as possible, and the plate sheet 14 is made as close as possible to the plate. Careful consideration is given to the body 5 such that it is attached closely. Then, the distance d between the objective lens 12 and the surface of the plate sheet 14 is kept at a constant value by the mechanical precision and precise adjustment.

[0012]

However, in the above-mentioned conventional laser plate making apparatus, with the same laser power,
In order to form a constant depression over the entire surface of the plate sheet 14, the objective lens 1 is in the order of several μm to several tens of μm.
Since it is necessary to keep the distance d between the surface 2 and the surface of the plate sheet 14 constant, it is necessary to improve the processing accuracy of the laser block 9 and the like, and the adjustment at the time of installation is complicated and critical. It was difficult and time consuming. In addition, if the plate sheet 14 has uneven thickness, the distance d changes, and the effect cannot be removed. Therefore, there is a problem that the depth of the recess 15 changes in the end.

The present invention has been made in consideration of the above problems, and provides a laser plate making apparatus capable of easily maintaining a constant distance between the plate sheet surface and the objective lens with a simple structure. The purpose is to provide.

[0014]

The present invention is described in, for example, FIG.
As shown in FIG. 2, the laser beam emitting means 2 is applied to the plate sheet 14 wound around the circumferential surface of the rotating cylinder 5.
6 (12) is moved in the axial direction of the cylinder 5 to irradiate the laser beam L to form a recess 1 in the plate sheet 14.
In the laser plate making apparatus for forming 5 to make a printing plate,
A spacer 78 integrally attached to the laser beam emitting means 26 (12) is provided, and when the recess 15 is formed in the plate sheet 14, the spacer 78 is brought into contact with the plate sheet 14 while the spacer 78 is in contact with the plate sheet 14. Plate sheet 1
4 is irradiated with the laser beam L.

[0015]

According to the present invention, the laser beam emitting means 26
When the spacer 78 integrally attached to (12) is provided and the recess 15 is formed in the plate sheet 14, the spacer 7
The plate sheet 14 is irradiated with the laser beam L while 8 is in contact with the plate sheet 14. Therefore, the spacer 78 moves in the front-rear direction (arrows H and I directions) of the plate sheet 14 following the surface of the plate sheet 14, so that the laser beam emitting means 26 (12) and the plate sheet 14 are moved.
The distance d between the surface of the plate sheet 14 and the surface of the plate sheet 14 is constant, and the surface of the plate sheet 14 is irradiated with the laser beam L having a constant laser power. Therefore, the recess 15 having the same depth can be formed in the plate sheet 14. Laser beam emitting means 2
Since it is only necessary to provide the spacer 78 integrally attached to 6 (12), the structure is simple. Also, adjustment of the focus etc. is easy.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the laser plate making apparatus of the present invention will be described below with reference to the drawings. In the drawings referred to below, the same reference numerals are given to those corresponding to those shown in FIG.

FIG. 2 shows the overall construction of the laser plate making apparatus according to this embodiment. In FIG. 1, 20 is a base, and a plate cylinder rotating unit 22 and a laser block moving unit 24 are provided on the base 20.

The laser block 26 as a laser beam emitting means can move along the guide rails 2 and 4 in the directions of arrows A and B, that is, in the axial direction of the plate cylinder 5.

The plate cylinder 5 is a cylinder made of metal, and a plate sheet 14 made of synthetic resin is wound around and fixed to the circumferential surface of the cylinder. Metal caps 28 and 29 are fixed to both ends of the plate cylinder 5. These caps 28,
29, shafts 30 and 31 are provided so as to project in the axial direction of the plate cylinder 5.

The shaft 30 is connected to a plate cylinder rotating motor 38 via a pulley 34 and a belt 36. When the plate cylinder rotating motor 38 is rotated, the plate cylinder 5 around which the plate sheet 14 is wound is rotated in the arrow E direction or in the arrow F direction which is the opposite direction.

The laser block mounting base 40 which constitutes the laser block moving unit 24 includes a cross roller table 39,
It is fixed to the mover 45 via the moving table 41 and the arm 42. The mover 45 is screwed into a ball screw 46 arranged between the bearings 43 and 44. The ball screw 46 is connected to a laser block moving motor 50 via a bearing 43 and a shaft joint 48.

Therefore, as the motor 50 rotates, the mover 45 moves in the direction of arrow A or B, and the arm 42 and the laser block mount 4 are attached to the mover 45.
The laser block 26 integrally attached via 0 moves along the guide rails 2 and 4 in the arrow A or B direction.

Next, before explaining the detailed construction of the laser block 26 which is the main part of the present invention, the electrical system of this embodiment will be explained.

FIG. 3 is a block diagram showing the configuration of the electrical system of this embodiment.

In FIG. 3, on the input operation panel 52,
When a panel switch on which a symbol such as “□” is drawn is operated, a signal (hereinafter, “status signal”) 54 corresponding to the operation, which represents a status such as stop or reset, is sent to a microcomputer (hereinafter, “CPU”). ) 56.

The CPU 56 outputs a forward rotation pulse or a reverse rotation pulse to the laser block moving motor driver 58 and the plate cylinder rotating motor driver 6 according to the status signal 54.
0 to supply the laser block moving motor 5 described above.
0 and the plate cylinder rotation motor 38 are rotationally controlled.

The plate cylinder 5 is rotated in the direction of the arrow E by the plate cylinder rotating motor 38, while the laser light emitted from the semiconductor laser 62 constituting the laser block 26 is passed through a collimator lens and an objective lens 12 (not shown). By irradiating the plate sheet 14 as the beam L,
The plate sheet 14 is provided with the recess 15 corresponding to the image data 63. In FIG. 3, reference numeral d denotes a distance between the objective lens 12 and the surface of the plate sheet 14, and the distance corresponds to the distance at which the objective lens 12 is focused on the surface of the plate sheet 14. That is, the laser beams L that have passed through the objective lens 12 are spaced so that the focal point of the laser beam L coincides with the surface of the plate sheet 14. From this point, the objective lens 12 can be regarded as a laser beam emitting means.

After the plate cylinder 5 makes one rotation in the direction of arrow E, the motor 50 for moving the laser block is rotated by a predetermined amount to rotate the laser block 26 in the direction of arrow A (see FIG. 2 and in FIG. 3, the front side of the paper surface). 1 pixel in the direction from the arrow direction toward the back side) to form a new depression 15 on the next line.

In this manner, the recess 15 having a shade according to the image data 63 is formed on the entire surface of the plate sheet 14 wrapped around the circumferential surface of the plate cylinder 5 under the control of the CPU 56.

The image data 63 is fetched in advance by an image scanner (not shown) or the like, and is stored in the data RAM 6
6 is stored.

The CPU 56 uses the data RAM 6 to store the image data 63 of the pixel, which is designated by the operation of the input operation panel 52 and is to be made on the plate sheet 14, from now on.
6 is supplied to the read gray scale conversion circuit 68.

The gray scale conversion circuit 68 has a function of converting the light and shade (gradation) of an image into a certain amount of laser irradiation time, and the image data 63 is processed as such and supplied to the laser driver 70. The semiconductor laser 76 is driven by the laser driver 70.

The density gradation of the image is determined by the depth z of the recess 15 formed, and as is well known, the depth z of the recess 15 is determined by the product of the laser irradiation time of the laser beam L and the laser power. It is determined. That is, the density gradation of the image is determined by the product of the laser irradiation time and the laser power.

In this case, the objective lens 12 and the plate sheet 14
When the distance d from the surface of the plate sheet 14 changes, the beam spot diameter of the laser beam L irradiated on the plate sheet 14 changes, and the laser power on the surface of the plate sheet 14 changes. When such a situation occurs, the density gradation of the image will not be the predetermined gradation.

FIG. 1A is a plan view showing the structure of a main part of the present invention including a laser block 26 for keeping the distance d constant. FIG. 1B is a side view thereof.

In FIGS. 1A and 1B, a moving table 41 which moves in the directions of arrows A and B is arranged on the guide rails 2 and 4 arranged in parallel, and a cross roller table 39 is provided on the moving table 41. A laser block mount 40 is attached.

The cross roller table 39 has arrows H and I.
The laser block 26 is moved in the direction, that is, the direction in which the laser block 26 approaches the plate sheet 14 or the direction in which the laser block 26 moves away from the plate sheet 14 (front-back direction).

On the surfaces of the moving table 41 and the laser block mounting base 40 facing each other, spring mounting pieces 80,
82 is arranged and fixed, and a plurality of compression springs 84 are mounted between the spring mounting pieces 80, 82.

In this case, the spring attachment piece 80 is moved by the mover 45 (see FIG. 2) via the moving table 41 and the arm 42.
Since it is connected to the laser block mounting base 40, the laser block mounting base 40 is always given a force to move in the direction of arrow H by the compression spring 84.

The laser block 26 is integrally mounted on the laser block mount 40. The laser block 26 basically has a laser block main body 72, the objective lens 12 and a laser housing portion 74.

A semiconductor laser 76 is provided in the laser accommodating portion 74.
The laser driver 70 (see FIG. 3) supplies a drive current signal to the semiconductor laser 76. The laser light emitted from the semiconductor laser 76 is collimated by a collimator lens (not shown) arranged in the laser block main body 72, and is further condensed by the objective lens 12. By irradiating the surface of the plate sheet 14 with the laser beam L emitted from the objective lens 12, the surface of the plate sheet 14 is focused and the recess 15 is formed.

Therefore, in order to keep the depth z of the recess 15 at a constant value, it is necessary that the laser power be constant at the surface irradiation position P of the plate sheet 14, and for that purpose, the objective lens 12 and The distance d between the surfaces of the plate sheet 14 must be maintained at a constant value (a constant value corresponding to the focal length of the objective lens 12).

Therefore, a rotary roller 78 functioning as a spacer is integrally provided from the laser block main body 72 via an arm 80. The rotating roller 78 is preferably made of metal such as stainless steel. Even if it is not a metal, a material having a relatively smooth surface and a relatively hard material may be used. From this point, the rotating roller 78 may be a member that does not rotate.

With this construction, the compression spring 84
As a result, the laser block mount 40 is given a force to move it in the direction of the arrow H, so that the rotating roller 78 is constantly pressed against the surface of the plate sheet 14 and comes into contact therewith. Therefore, the rotating roller 78 rotates in the arrow G direction with respect to the plate sheet 14 rotated in the arrow E direction.

In this case, the rotating roller 78 is the plate sheet 1
4 and the objective lens 12, and as a result, the distance d between the objective lens 12 and the surface of the plate sheet 14 is d.
Functions so that becomes a constant value.

Here, the rotary roller 78 is on the front side in the moving direction of the laser block 26, in other words, the laser beam L.
On the virtual scanning line in front of the moving direction (direction of arrow A) (on the line where the laser beam L moves on the plate sheet 14 from now on)
Since it is arranged on the plate sheet 14, the vehicle does not travel on the recess 15 (see FIG. 1A), and travels on the plate sheet 14 while making a smooth contact. That is, the rotating roller 78
Does not affect the shape of the recess 15 and is not affected by the shape of the recess 15.

The rotary roller 78 is arranged so that the laser beam L is irradiated onto the plate sheet 14 at the irradiation position P with respect to the plate sheet 1.
4 on the upstream side in the rotation direction of 4 (direction of arrow E) (see FIG. 1B)
It may be arranged at. Here, on the downstream side K,
Since the recess 15 is formed, the rotary roller 78 is formed there.
Is not preferable.

The rotary roller 78 is used for the objective lens 12
It is better to arrange them as close to each other as possible, and it is needless to say that the distance d between the objective lens 12 and the surface of the plate sheet 14 can be maintained at a more constant distance by doing so. From that point, the rotary roller 78 may be changed to a configuration in which the rotary roller 78 and the objective lens 12 are integrally arranged.

Instead of the rotating roller 78, a rotatable sphere or a non-rotating sphere may be adopted.

As described above, according to the above-described embodiment, the rotary roller 7 integrally attached to the laser block 26.
8 is provided to irradiate the plate sheet 14 with the laser beam L while pressing the rotary roller 78 against the plate sheet 14 by the compression spring 84 when forming the recess 15 in the plate sheet 14. Therefore, the rotating roller 78 follows the surface of the plate sheet 14 in the front-back direction of the plate sheet 14 (directions of arrows H and I).
Therefore, once the distance d between the objective lens 12 and the surface of the plate sheet 14 is adjusted so that the laser beam L is focused on the surface of the plate sheet 14, the objective lens 12 and the plate are always The distance d from the surface of the sheet 14 becomes constant, and the surface of the plate sheet 14 is irradiated with a laser beam L having a focused and constant laser power.
Therefore, the recess 15 having the same depth can be formed in the plate sheet 14.

In this case, even if the position of the surface of the plate sheet 14 is deviated by, for example, several tens of μm due to the eccentricity of the plate cylinder 5, the objective lens 12 follows it and moves in the front-back direction (arrows H, I
Direction), the objective lens 12 and the plate sheet 1 are moved.
The distance d from the surface of No. 4 can be maintained at a constant value.

Even if the thickness of the plate sheet 14 changes, the distance d between the objective lens 12 and the surface of the plate sheet 14 can be kept constant.

As a result, according to the above-described embodiment, in order to keep the distance d between the objective lens 12 and the surface of the plate sheet 14 constant, the precision such as the eccentricity of the plate cylinder 5 and other mechanical precision are increased. It becomes unnecessary to do so, and the position can be easily adjusted with a simple structure.

The present invention is not limited to the above-described embodiments, and it goes without saying that various configurations can be adopted without departing from the gist of the present invention.

[0055]

As described above, according to the present invention,
A spacer integrally attached to the laser beam emitting means is provided, and when forming a recess in the plate sheet, the plate sheet is irradiated with a laser beam while the spacer is in contact with the plate sheet. For this reason, since the spacer moves in the front-back direction of the plate sheet following the surface of the plate sheet, the distance between the laser beam emitting means and the surface of the plate sheet becomes constant, and the surface of the plate sheet becomes uniform. A laser beam having a laser power is emitted. For this reason, it is possible to obtain the effect that the depressions having the same depth can be formed in the plate sheet.

Further, since it is only necessary to provide the spacer integrally attached to the laser beam emitting means, it is possible to obtain an effect that the structure is simple and the adjustment of the above-mentioned interval is also simple.

[Brief description of drawings]

FIG. 1A is a plan view showing a main configuration of an embodiment of a laser plate making apparatus according to the present invention. B is a partial cross-sectional view of the side surface.

FIG. 2 is a perspective view showing the overall configuration of an embodiment of a laser plate making apparatus according to the present invention.

FIG. 3 is a system diagram showing an electrical configuration of the example of FIG.

FIG. 4A is a plan view showing a partial configuration of a laser plate making apparatus according to a conventional technique. B is a partial cross-sectional view of the side surface.

[Explanation of symbols]

 5 plate cylinder 12 objective lens 14 plate sheet 15 indentation 26 laser block 76 semiconductor laser 78 rotating roller d spacing L laser beam

Claims (6)

[Claims] 1. A recess is formed in the plate sheet by irradiating the plate sheet wound around the circumferential surface of a rotating cylinder with a laser beam while moving the laser beam emitting means in the axial direction of the cylinder. In the laser plate making apparatus for making a printing plate by providing a spacer integrally attached to the laser beam emitting means, when forming a recess in the plate sheet, the laser beam while contacting the spacer with the plate sheet A laser plate making apparatus, wherein the plate sheet is irradiated with the laser beam from an emitting means. 2. The laser plate making apparatus according to claim 1, wherein the spacer is arranged on the front side in the moving direction of the laser beam emitting means. 3. The laser plate making apparatus according to claim 1, wherein the spacer is arranged on an upstream side in a rotation direction of the cylinder with respect to an irradiation position of the laser beam on the plate sheet. 4. The spacer is arranged on the front side in the moving direction of the laser beam emitting means, and is arranged on the upstream side in the rotating direction of the cylinder with respect to the irradiation position of the laser beam on the plate sheet. The laser plate making apparatus according to claim 1, wherein: 5. The laser plate making apparatus according to claim 1, wherein the spacer is a rotating roller. 6. The surface of the plate sheet in contact with the spacer is spherical.
The laser plate making apparatus according to any one of 1.