JP2002225237A - Imaging system - Google Patents

Abstract

(57) [Object] To provide an imaging system for capturing a periodic image on a web conveyed at high speed at an accurate position in synchronization with the cycle. Kind Code: A1 A transfer detecting means for detecting a transfer amount of a web, a synchronous control means for inputting the transfer amount and a coordinate deviation outputted by a processing means, and outputting a trigger at a timing for reducing the coordinate deviation; A light-emitting means for illuminating the web by inputting and instantaneously emitting light, an image-capturing means for capturing an image of the illuminated web and outputting an image-capturing signal; Processing means for comparing coordinates with predetermined coordinates to output a coordinate deviation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of capturing images to obtain captured images (data). In particular, the present invention relates to an imaging system that captures a periodic image on a transferred web in synchronization with the cycle.

[0002]

2. Description of the Related Art In a multi-color printing machine for printing on a web printing paper, a printing registration is required for overprinting.
The image of the print register mark printed on the web is performed. Further, in order to inspect the quality of the printed matter, an image of the entire printing surface of the web is taken. At this time, the picture on the printing surface of the web is a periodic image with the printing plate image as one unit. Therefore, such imaging is usually performed periodically in accordance with the cycle of the picture.

Heretofore, as a method of imaging, a method of giving one trigger signal for one rotation of a plate cylinder of a printing press using an encoder to take an image, a mark for giving an imaging timing with a general-purpose laser sensor, and the like have been proposed. There is known a method of capturing an image at the timing of reading the data.

[0004]

However, in the method using an encoder as described above, if the web expands and contracts or slips during transportation, the imaging timing is shifted and a captured image at a fixed position cannot be obtained. In a method using a general-purpose laser sensor as described above, since the response speed of the sensor itself is generally low, a high-speed
When the web is being transported at 0 m / min (3.33 m / sec) or more, the imaging timing is shifted, and a captured image at a fixed position cannot be obtained.

The present invention has been made to solve such a problem, and an object of the present invention is to provide an image pickup system for picking up a periodic image on a web conveyed at high speed at an accurate position in synchronization with the cycle. To provide.

[0006]

The above object is achieved by the present invention described below. That is, an image pickup system according to claim 1 of the present invention is an image pickup system for picking up a periodic image on a transferred web in synchronization with the cycle, the transfer detection unit, the synchronization control unit, and the light emitting unit. When,
An image pickup unit and a processing unit are provided, wherein the transfer detection unit detects the transfer amount of the web, and the synchronization control unit inputs the transfer amount and a coordinate deviation output by the processing unit, and outputs the coordinate. A trigger is output at a timing to reduce the deviation, the light emitting unit illuminates the web by inputting the trigger and flashing instantaneously, and the image capturing unit captures an image of the illuminated web and outputs an image signal. The processing means outputs the image pickup signal to generate a picked-up image, compares the coordinates of the picked-up image with predetermined coordinates, and outputs the coordinate deviation.

According to the present invention, the transfer amount of the web is detected by the transfer detecting means, and the synchronous control means inputs the transfer amount and the coordinate deviation outputted by the processing means. The illuminated web is illuminated by the light emitting unit that is output and the trigger is input, and the web is illuminated, the illuminated web is imaged by the imaging unit, an imaging signal is output, and the imaging signal is input by the processing unit, and the captured image is Is generated,
The coordinates of the captured image are compared with predetermined coordinates, and a coordinate deviation is output. That is, the timing of the next imaging is operated so as to reduce the coordinate deviation of the captured image. Therefore, there is provided an imaging system for imaging a periodic image on a web conveyed at high speed at an accurate position in synchronization with the cycle.

[0008]

Next, an embodiment of the present invention will be described. FIG. 1 shows an example of the configuration of the imaging system of the present invention. In FIG. 1, 1 is a pulse generator (PG), 2 is a synchronization control unit, 3 is a light emission control unit, 4 is a ring illumination, 5 is a CCD camera, and 6 is a data processing unit.

The pulse generator 1 is a rotation detector installed on a rotating shaft. The pulse generator 1 outputs a number of pulses corresponding to the rotation amount of the rotation shaft. Also, the number of pulses output by the pulse generator 1 during one rotation of the rotation axis is determined. The pulse generator 1 is usually installed on a rotation shaft of a web transfer mechanism in a web processing device such as a printing press or a rotation shaft of a mechanism linked to the web transfer. For example, in a printing press, it is installed on a rotation axis of a plate cylinder capable of synchronizing with a pattern printed on a web (printing paper), or a rotation axis of a mechanism linked therewith. Therefore, by counting the pulses output by the pulse generator 1, it is possible to indirectly detect the web transfer amount and the cycle of the print pattern.

[0010] The synchronization control unit 2 receives pulses output from the pulse generator 1 and counts the number of pulses. Since the count value is a count value that can be associated with the web transfer amount, the cycle of the print pattern, and the like, the synchronization control unit 2 calculates the relationship between the count value and the web transfer amount and the cycle of the print pattern. Keep it. Then, the count value is reset in that cycle. The synchronization control unit 2 outputs a trigger when the periodic count value matches a predetermined count value.

The predetermined count value, that is, the trigger output count value is not a constant count value but a variable value. By changing the trigger output count value, it is possible to change a position in a cycle of a print pattern or the like, that is, a position at which a trigger is output. Therefore, the imaging position when the imaging is performed in response to the trigger can be changed by changing the trigger output count value. This makes it possible to introduce a print pattern or the like to be imaged, such as a register mark, into the imaging field of view. Also,
This makes it possible to correct the imaging position with respect to the introduction error caused by fluctuation due to disturbance or the like.

The synchronization control unit 2 receives the coordinate deviation output from the data processing unit 6 (described later). Synchronous control unit 2
Outputs a trigger at a timing to reduce the coordinate deviation based on the count value and the coordinate deviation. That is, the synchronization control unit 2 calculates the operation amount (correction amount) of the trigger output count value according to the coordinate deviation. In this calculation, the relationship between the count value of the pulses output from the pulse generator 1 and the transport amount (that is, coordinates) of the web is used. And
The synchronization control unit 2 operates the trigger output count value according to the calculated operation amount (see FIG. 3 described later).

The light emission control unit 3 supplies a power for causing the ring illumination 4 to emit light instantaneously (flash light emission) by inputting a trigger. As shown in FIG. 1, the trigger is directly output from the synchronization control unit 2 to the CCD camera 5, and the trigger via the CCD camera 5 is output to the light emission control unit 3. This is to make the ring illumination 4 emit light instantaneously when the CCD camera 5 is ready for imaging.

The ring illumination 4 illuminates an imaging area on the web by emitting light instantaneously upon receiving power supply from the light emission control unit 3. This flash makes it possible for the fast-moving web to be imaged substantially stationary. LED (light em)
an itting diode), a xenon lamp, or the like.

The CCD camera 5 has an integrated sensor in which light receiving elements are two-dimensionally arranged, and is a camera for imaging a two-dimensional area. The CCD camera 5 scans the light receiving element and outputs an imaging signal corresponding to the amount of received light. When the trigger output from the synchronization control unit 2 is input, the CCD camera 5 opens the electronic shutter and completes the imaging preparation. Then, after completing the preparation for imaging, the CCD camera 5 outputs (transfers) a trigger to the light emission control unit 3. The electronic shutter in the CCD camera 5 is opened at predetermined time intervals, during which instantaneous light emission by the ring illumination 4 is performed. When the instantaneous light emission is performed, an image of a register mark, a printed pattern, or the like existing on the web in the imaging area is performed.

The data processing section 6 receives an image pickup signal output from the CCD camera 5. And A / D (analog-to-
digital) to generate a captured image (data).
This captured image can be used for multiple purposes. For example, it can be used for monitoring a print register (monitor) in a multi-color printing machine, quality inspection of a printed material, and the like.

Based on the captured image, the data processing unit 6
Calculates coordinates, compares the coordinates with predetermined coordinates, and outputs a coordinate deviation. FIG. 3 shows an example of the processing in the data processing unit 6 as an explanatory diagram. The inside of the rectangular frame shown in FIG. 3 is a captured image. In the example shown in FIG. 3, the imaging target is a register mark. Let the coordinates of the left side of the rectangular frame be Xmin, the coordinates of the right side of the rectangular frame be Xmax, the coordinates of the upper side of the rectangular frame be Ymax, and the coordinates of the lower side of the rectangular frame be Ymin.
Also, the coordinates of the register mark are (x, y).

The target value of the position of the register mark in the captured image is defined as the center position in the vertical direction (Y direction) of the captured image. That is, the center coordinates in FIG.
Ymin) / 2. At this time, the coordinate deviation Δy of the register mark in the Y direction is Δy = y− (Ymax−Ymin) /
It becomes 2. The data processing unit 6 calculates this coordinate deviation Δy and outputs it to the synchronization control unit 2. The synchronization control unit 2 inputs the coordinate deviation Δy and calculates a correction amount (operation amount) yh, for example,
By applying the function f (), calculation is performed as yh = f (Δy).

Next, the operation of the above-described configuration of the imaging system of the present invention will be described. FIG. 2 is a flowchart showing a process of the operation of the imaging system of the present invention applied to a printing press. First, in step S1 of FIG. 2, when printing is performed in the printing press, the ring illumination 4 flashes instantaneously under the control of the pulse generator 1, the synchronization control unit 2, the light emission control unit 3, and the like,
The D camera 5 takes one image per rotation of the plate cylinder.

Next, in step S2, the data processing unit 6 extracts the center coordinates of the register mark in the obtained captured image. The center coordinates can be obtained by applying a known method such as a method of calculating the center of gravity in the binarized image or a method of calculating from the peak of the frequency distribution in the xy axis projection. Further, a deviation in the transfer direction (Y direction) between the center coordinates of the captured image and the center coordinates of the register mark, that is, a coordinate deviation is calculated.

Next, in step S3, the data processing section 6 calculates a correction amount of the imaging timing. Deviations from the target coordinates are due to web expansion and contraction and slippage in the transport mechanism. The calculation here is performed by the control device based on the deviation (coordinate deviation) from the target value, etc., performed by the control calculation unit in order to generate an operation amount necessary for the control system to perform a required operation. It is a similar operation.

Next, in step S4, the data processing section 6 determines whether or not printing is continued, and if not, ends the operation process in the imaging system. If the printing is continued, the process proceeds to step S5. In step S5, the synchronization control unit 2 corrects the imaging timing based on the correction amount described above. Next, the process returns to step S1, and the subsequent steps described above are repeated.

[0023]

As described above, according to the imaging system according to the first aspect of the present invention, a periodic image on a web conveyed at high speed can be imaged at an accurate position in synchronization with the cycle. A possible imaging system is provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a configuration in an imaging system of the present invention.

FIG. 2 is a flowchart showing a process of an operation in the imaging system of the present invention applied to a printing press.

FIG. 3 is an explanatory diagram illustrating an example of a process of calculating a coordinate deviation in a data processing unit in the imaging system of the present invention.

[Explanation of symbols]

 Reference Signs List 1 pulse generator 2 synchronization control unit 3 light emission control unit 4 ring illumination 5 CCD camera 6 data processing unit

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 2C250 EB26 EB27 EB29 EB38 EB43 2G051 AA34 AB11 BA20 BC02 BC03 CA04 CB01 CD06 CD07 DA01 DA05 EA12 ED23 5C054 AA01 CB04 CC05 CG01 CH04 EA01 FC01 HA02

Claims (1)

[Claims] 1. An imaging system for imaging a periodic image on a transferred web in synchronization with the period,
A transport detection unit, a synchronization control unit, a light emitting unit, an imaging unit, and a processing unit, wherein the transport detection unit detects a transport amount of the web, and the synchronization control unit determines the transport amount. Inputting the coordinate deviation output by the processing means, outputting a trigger at a timing to reduce the coordinate deviation, the light emitting means illuminating the web by inputting the trigger and flashing instantaneously, and the imaging means Captures the illuminated web and outputs an imaging signal, the processing unit receives the imaging signal to generate a captured image, compares the coordinates of the captured image with predetermined coordinates, and An imaging system, which outputs a coordinate deviation.