JP2000202980A - Printing original plate laser image drawing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simply structured printing original plate laser image drawing device with a function to prevent control instability from occurring with a clamp for fixing a printing original plate. SOLUTION: In the printing original plate laser image drawing device 10, a laser beam 23a is condensed to the surface of a cylindrical body 22 in the radial direction of a rotor by a laser beam condensing means 25 provided on a mobile table 24 which travels in parallel with a rotary shaft 21 along the surface 22a of the cylindrical body 22, and consequently, a printing original is imaged on the surface of the cylindrical body 22. On the mobile table 24, two displacement sensors 26a, 26b for measuring a displacement in the radial direction on the surface of the cylindrical body 22, are provided. Further, an output from a photoelectric sensor 36 for identifying an output from the displacement sensors 26a, 26b and the non-presence of the printing master on the side face of the cylindrical body 22 is entered to a sample hold circuit, and an output signal to be sent by the sample hold circuit controls a linear motor 27. Entry of data to a mirror controller 34 results in the elimination of significant variability in a clamping part, so that the follow-up action of the linear motor 27 is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing plate laser drawing apparatus for drawing a printing original by focusing a laser beam on the surface of a printing plate cylinder, and in particular, a projection such as a clamp on the surface of the cylinder. The present invention relates to a laser writing apparatus capable of performing stable control even if it is provided.

[0002]

2. Description of the Related Art Conventionally, a printing original plate laser drawing apparatus using a semiconductor laser by the present applicant has been known as an apparatus for producing an original plate for gravure printing (Utility Model Registration No. 2554332). As shown in FIG. 11, the printing apparatus cylinder 2 is rotated around a rotation axis 21.
A laser 23a for drawing a print original on the surface of 2 is generated by a drawing laser generating means 23, and the laser 23a is provided on a moving table 24 which moves in parallel with the rotation axis 21 along the surface 22a of the cylindrical body 22. By the laser focusing means 25,
A printing original plate laser drawing apparatus 20 for condensing light on a surface of a cylindrical body in a radial direction of a rotating body and drawing a printing original on the surface, and displacing a moving table 24 with a displacement of the surface of the cylindrical body 22 in a radial direction. At least one or more displacement sensors 26a to measure,
26b, and a condensing unit 25 via a linear driving unit 27 that moves in the radial direction following the displacement measured on the moving table 24.

[0003] By constructing the printing original plate laser drawing apparatus 20 as described above, the cylinder rotated at a high speed bends due to the imbalance of its balance, and the surface of the cylinder is displaced in the radial direction. As a result, the drawing of the printed document is blurred beyond the focal range of the original document, and the yield of the printing original plate is significantly reduced. In other words, the laser beam can be focused on the surface of the cylindrical body with high precision, and the printed document can be drawn without blurring.

[0004]

However, in the above-described laser drawing apparatus, the printing original plate 28 is fixed to the surface of the cylindrical body, as is apparent from FIG. 12 (a) showing a side view of the cylindrical body. Clamps 29a and 29b
The height of the clamp (about 5 mm) is larger than the magnitude of the displacement of the surface of the cylindrical body 22 (about ± 0.1 mm), so that when the laser focus reaches the position of the clamp, As a result of the mobile table 24 attempting to move significantly, control may become unstable or impossible to control.
The output of the displacement sensor and the corresponding change in the position of the movable base 24 at this time are shown in FIG.

In order to eliminate the instability of control when the laser focus reaches the position of such a clamp,
When focus control by optical servo control is disturbed,
There is known a technology in which switching to capacitance servo control is performed, focus control is performed to keep the position of a focus control lens constant by keeping the capacitance constant, and laser light irradiation is stably performed. (JP-A-7-60934). In this method, the position of a clamping plate that stops the plate sheet on the plate cylinder is detected by a rotary encoder that detects the rotational position of the plate cylinder, and capacitance servo control is performed at this detection position, and the detection state of the focus detection unit is changed. By switching to optical servo control when the abnormality disappears, accurate focus control by rapid optical servo control is enabled.

[0006] As a technique related thereto, a technique for removing disturbance mixed in an autofocus return beam in laser plate making (Japanese Patent Laid-Open No. 10-34866) and a lens position sensor are provided to continuously perform focus servo. (Japanese Patent Application Laid-Open No. 10-24546)
However, there are the following problems. That is, in these techniques, optical servo control and another servo control by a position sensor signal switched by a rotary encoder are necessary, and the configuration of the optical system becomes complicated,
Further, since a high-performance processing system such as a DSP control circuit is required for signal processing and the circuit becomes complicated, there is a disadvantage that the number of parts increases and the cost increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks.
An object of the present invention is to provide a printing original plate laser drawing apparatus capable of eliminating control instability and inability to control when a laser focus reaches a position of a clamp for fixing a printing original plate on a cylindrical body surface. . Another object of the present invention is to provide a printing original plate laser drawing apparatus capable of appropriately switching between closed loop and open loop by adding servo control using a simple analog position sensor signal and one binary sensor. .

It is another object of the present invention to provide a printing original plate laser drawing apparatus having a simple configuration which does not require optical servo control for optically detecting the focus of a laser beam. Another object of the present invention is to provide a reliable and inexpensive printing original plate laser drawing apparatus, which has a simple configuration and a small number of parts.

[0009]

In order to achieve the above object, a printing original plate laser drawing apparatus according to the present invention comprises a laser for drawing a printing original on the surface of a printing original plate cylinder which is rotated around a rotation axis. Is generated by drawing laser generating means, and the generated laser is moved in parallel with the rotation axis along the surface of the cylindrical body. At least one or more displacement sensors for focusing on the surface and measuring the displacement of the surface of the cylindrical body in the radial direction on the movable table, and moving in the radial direction following the measured displacement on the movable table. A light condensing means is provided via a driving means, and a position detection sensor for detecting a position of the printing original on the surface of the cylindrical body is provided when drawing a print original on the surface of the cylindrical body. When detecting and not detecting In is obtained to switch the feedback signal of the lens position of the focusing means.

The feedback signal of the lens position of the light condensing means may be the displacement of the displacement sensor when the printing original is detected, and may be the displacement of the displacement sensor at the starting point or the end point of the printing original when the printing original is not detected. it can. Also,
The feedback signal of the lens position of the light condensing means changes the displacement of the displacement sensor when the printing original is detected, and smoothly changes from the displacement of the displacement sensor at the end point of the printing original to the displacement at the starting point when the printing original is not detected. It is preferable that the feedback signal is used to control the lens position of the light collecting means.

Further, in the above case, a delay time is arbitrarily set between a signal by a position detection sensor for detecting a position of a clamp for fixing the printing plate to the surface of the printing plate cylinder and a signal holding circuit. By providing a possible delay circuit and adjusting the delay time to adjust the switching timing of the feedback signal of the lens position, the required accuracy of the installation position of the position detection sensor can be reduced and the installation can be easily performed. .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of a printing original plate laser drawing apparatus according to the present invention will be described. FIG. 1 shows a printing original plate laser drawing apparatus 10 of the present invention, and the same parts as those of the conventional apparatus 20 are denoted by the same reference numerals.

In FIG. 1, reference numeral 20 denotes a printing plate laser drawing apparatus, 21 denotes a rotating shaft, 22 denotes a printing plate cylinder, 23 denotes drawing laser generating means, 24 denotes a moving table, 25 denotes laser condensing means, and 26a and 26b denote displacements. Sensor, 28 is the original printing plate, 2
9a and 29b are clamps, 34 is a mirror controller,
Reference numeral 35 denotes a reflection plate, and 36 denotes a photoelectric sensor. The printing original plate cylinder 22 is supported by bearings 30 a and 30 b at both ends thereof, and is rotated around the rotation shaft 21 at a predetermined rotation speed by a motor 31 coupled to one of the rotation shafts 21.

The laser 23a is generated by the drawing laser generating means 23, and the laser 23a
The laser light condensing means 25 provided on a movable table 24 that moves in parallel with the rotation axis 21 along 2a condenses the light on the surface of the cylindrical body in the radial direction of the rotating body, and draws a print original on the surface. The drawing laser generating means 23 comprises a laser controller 23b and a laser generator 23c. In the present invention, a laser mirror is used as the laser condensing means 25, and a linear motor or servomotor is used as the linear driving means 27.

The displacement table 24 has two displacement sensors 26a and 26 for measuring the displacement of the surface of the cylindrical body 22 in the radial direction.
b is provided, and a condensing unit 25 is provided via a linear driving unit 27 that moves in the radial direction following the displacement measured by the displacement sensor. The moving table 24 is installed along a surface of the cylindrical body 22 on a ball screw 32 arranged in parallel with the rotating shaft 21 of the cylindrical body 22, and is moved in parallel with the rotating shaft 22 by a servomotor 33 coupled to one end of the moving table 24. .

Therefore, the laser 23 condensed on the surface of the cylindrical body 22 by the parallel movement of the movable table 24 with the rotation shaft 22.
“a” draws a print original on the printing original plate on the surface of the cylindrical body 22. As described above, the displacement table 24 has two displacement sensors 2 for measuring the displacement of the surface of the cylindrical body 22 in the radial direction.
6a and 26b are provided, and the moving table 24 moves in the radial direction of the surface of the cylindrical body 22 via the linear motor 27 following the displacement detected by the displacement sensor.

The displacement sensors 26a and 26b
The laser 23a is provided at a position symmetrical with respect to the center of the optical path, and is located in the reverse rotation direction of the surface of the cylindrical body 22 from the focusing position of the laser 23a. The outputs of the displacement sensors 26a and 26b are averaged, that is, the radial displacement of the cylinder corresponding to the axial deflection of the cylinder 22 is determined by the mirror controller 34.
The mirror controller calculates the average value, calculates the control amount of the linear motor 27, outputs the control amount to the linear motor, operates the linear motor 27 in synchronization with the measurement position, and focuses the laser 23a. Move the position accurately.

As shown in FIG. 2, a reflecting plate 3 for identifying portions other than the printing original plate 28 is provided on the side surface of the cylindrical body 22.
5 is provided between the clamps 29a and 29b, and a photoelectric sensor 36 for detecting the position of the reflection plate 35 is arranged corresponding to the position of the reflection plate on the side surface of the cylindrical body. The photoelectric sensor 36 determines the position of the reflecting plate 35, that is, the state where the printing original plate 28 is not present, and outputs the output from the sample holding circuit 37.
(SAMPLE / HOLD) signal 37a (hold at L) (FIG. 3). On the other hand, the outputs 26c of the displacement sensors 26a and 26b are also input to the sample and hold circuit 37, but are output as they are when the (SAMPLE / HOLD) signal 37a is (H), and the (SAMPLE / HOLD) signal 37a is (L). Then, the signal level at the time of the fall is held. An output 37b of the sample and hold circuit 37 is input to a displacement sensor input of the mirror controller 34.

FIG. 4 shows the relationship among the output of the photoelectric sensor, the output of the displacement sensor, and the output of the sample-and-hold circuit as described above. Follow-up becomes easy. In the above, the case where the photoelectric sensor 36 is used as the position detection sensor has been described. However, an absolute encoder may be attached to the cylinder 22 instead of the photoelectric sensor, and a digital circuit may be formed from the output value of the (SAMPLE / HOLD) signal.

In order to further suppress transient vibration, a low-pass filter may be connected in series to the output side of the sample-and-hold circuit, and a circuit for smoothing a sudden change in the sensor signal at the time of switching may be inserted. FIG. 5 shows an embodiment which can be applied even when the displacement difference δ between the starting point and the ending point of the printing original plate 28 is large, and the positional relationship between the displacement sensor, the photoelectric sensor, and the reflecting plate is the same as in FIGS. However, a circuit 38 for generating a short pulse by the rise of the output 36a of the photoelectric sensor is provided, and the sample / hold of the sample and hold circuit is switched by the output pulse 38a. And the output 37a of the sample hold circuit is the output 3 of the photoelectric sensor.
6a, that is, the output of the photoelectric sensor is turned off.
A multiplexer circuit 39 outputs a displacement sensor output at (H) and a sample and hold circuit output at ON (L).

With this configuration, the displacement difference δ of the signal input to the sensor input of the mirror signal is changed from an area on the printing original plate 28 to be accurately controlled to an area where accurate control between the clamps is not required. Since the transition is made, accurate control in an area on the printing original plate becomes possible. Since the transient vibration due to the displacement difference δ may be converged within the region between the clamps, the cutoff frequency can be increased even when a low-pass filter for smoothing the transition is inserted. Can be suppressed (FIG. 6).

In the apparatus having the above configuration, the printing original 2
In order to detect the positions of the start point and the end point of 8 by the photoelectric sensor 36, it is necessary to exactly match the positions of the photoelectric sensors, but the conditions for setting the positions can be relaxed. 7 and 8 show such an embodiment, in which an inverter and a 2
Two delay circuits 40a and 40b are provided, and the output 36a of the photoelectric sensor is input to the delay circuits. One signal is inverted through an inverter to set / reset the SR latch 41, and the output 41a of the SR latch is used as a (SAMPLE / HOLD) signal. The delay time of each of the delay circuits 40a and 40b can be set arbitrarily, whereby the timing of the (SAMPLE / HOLD) signal 41a can be accurately printed by adjusting the delay time even if the accuracy of the position setting of the photoelectric sensor is coarse. The starting point and the end point of the original plate 28 can be adjusted.

FIGS. 9 and 10 show a pulse generation circuit 38.
In this embodiment, the displacement at the starting point of the printing original plate 28 is held by the sample and hold circuit 37, and the input 42a of the low-pass filter 42 is connected to the displacement sensor output 26c Is switched to the output 37a of the sample and hold circuit 37 via the first switch SW1. Therefore, if the characteristics of the low-pass filter are appropriately set, the low-pass filter output 42b
Converges smoothly from the displacement at the printing plate end to the displacement at the starting point. If this is used as a feedback signal in a portion without the printing original plate, that is, a sensor input 34a of the mirror controller 34 via a second switch SW2 which is switched in conjunction with the first switch SW1, a steep change in the feedback signal is obtained. Disappears and stable control over the entire circumference becomes possible.

[0024]

As described above, according to the printing original plate laser drawing apparatus of the present invention, control instability and inability to control when the laser focus reaches the position of the clamp for fixing the printing original plate are eliminated. It has the advantages of simple structure, high reliability, and low cost because of the small number of parts.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a printing original plate laser drawing apparatus according to the present invention.

FIG. 2 is a side view showing one embodiment of the printing original plate laser drawing apparatus of the present invention.

FIG. 3 is a circuit diagram showing one embodiment of the relationship between the displacement sensor output, the photoelectric sensor output, and the mirror controller input of the present invention.

FIG. 4 is a graph showing a relationship among a displacement sensor output, a photoelectric sensor output, and a sample and hold circuit output in the circuit diagram of FIG. 3;

FIG. 5 is a circuit diagram showing another embodiment of the relationship between the displacement sensor output, the photoelectric sensor output, and the mirror controller input of the present invention.

FIG. 6 is a graph showing a relationship among a displacement sensor output, a photoelectric sensor output, a pulse generation circuit output, a sample hold circuit output, and a multiplexer circuit output in the circuit diagram of FIG.

FIG. 7 is a circuit diagram showing another embodiment in which a delay circuit is provided on the output side of the photoelectric sensor.

8 is a graph showing a relationship among a photoelectric sensor output, a delay circuit output, and a latch output in the circuit diagram of FIG. 7;

FIG. 9 is a circuit diagram showing another embodiment of the relationship between the displacement sensor output, the photoelectric sensor output, and the mirror controller input of the present invention.

10 is a graph showing a relationship among a displacement sensor output, a photoelectric sensor output, a pulse generator output, a sample and hold circuit output, a low-pass filter input / output, and a mirror controller sensor input in the circuit diagram of FIG.

FIG. 11 is a front view of a conventional printing original plate laser drawing apparatus.

FIG. 12 is a side view showing a main part of a conventional printing original plate laser drawing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 ... Printing original plate laser drawing apparatus 21 ... Rotation axis 22 ... Printing original plate cylinder 23 ... Drawing laser generating means 24 ... Moving table 25 ... Laser focusing means 26a, 26b ... Displacement sensor 28 ... Printing originals 29a, 29b ... Clamp 34 ... mirror controller 35 ... reflector 36 ... photoelectric sensor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shinya Namiki 2-1-1 Oda Sakae, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Inside Showa Electric Cable Co., Ltd. No. 1-1, Showa Electric Wire & Cable Co., Ltd. (72) Inventor Ikuma Nariyoshi 2-1-1, Oda Sakae, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture, Japan Inside of Showa Electric Wire & Cable Co., Ltd. (72) Inventor, Sukehiro Akama 2-1-1, Oda-ku, Showa Electric Wire & Cable Co., Ltd. F-term (reference) 2H044 AJ07 BA01 BA09 BE01 BE09 BF01 BF07 DA01 DB00 DC02 2H051 AA10 BB31 CB23 CD01 CD28 DC17 DD20 FA01 FA09 2H084 AA05 AE16 CC03

Claims (4)

[Claims] 1. A drawing laser generating means generates a laser for drawing a print original on the surface of a printing plate cylinder rotated about a rotation axis, and emits the generated laser along the surface of the cylindrical body. The laser condensing means provided on a movable table that moves in parallel with the rotation axis focuses the light on the surface of the cylindrical body in the radial direction of the rotating body, and the movable table includes the surface of the cylindrical body. Providing at least one or more displacement sensors for measuring the displacement in the radial direction, and providing the focusing unit via the linear drive unit that moves in the radial direction following the measured displacement on the movable table. A printing plate laser drawing apparatus for drawing a printing original on the surface of the cylinder, a position detection sensor for detecting a position of the printing plate on the surface of the cylinder, and detection of the printing plate by the position detection sensor. Undetected during the in the printing plate laser drawing apparatus characterized by switching a feedback signal of the lens position of the focusing means. 2. The method according to claim 1, wherein the displacement of the displacement sensor at the time of detection of the printing original plate and the displacement of the displacement sensor at the starting point or the end point of the printing original plate at the time of non-detection of the printing original plate are used as a feedback signal of the lens position of the light collecting means. Claim 1.
The printing original plate laser drawing apparatus described in the above. 3. A feedback signal is generated so that the displacement of the displacement sensor is detected when the printing original is detected, and the displacement is smoothly changed from the displacement of the displacement sensor at the end point of the printing original to the displacement at the starting point when the printing original is not detected. 2. The printing plate laser drawing apparatus according to claim 1, wherein the feedback signal controls the lens position of the light condensing means. 4. A delay circuit capable of arbitrarily setting a delay time between a signal from a position detection sensor for detecting a position of a clamp for fixing a printing original plate to the surface of a printing original cylinder and a signal holding circuit. 4. The printing original plate laser drawing apparatus according to claim 2, wherein the switching timing of the feedback signal of the lens position is performed by adjusting the delay time.