JP4372979B2 - Mark detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of detecting a mark printed on an article.
[0002]
[Prior art]
In order to clearly indicate a defective article or a defective portion in a production line such as a printing machine or a box making machine, marking is performed with an inkjet printer or the like.
[0003]
[Problems to be solved by the invention]
When printing is performed on an article that is transported at a high speed by a dot printer such as an ink jet, the distance between the dots is increased, resulting in a sparse mark. In order to detect such a mark in a subsequent process, it is necessary to capture the mark using a camera and perform image processing on the captured image to determine the presence or absence of the mark. Further, in order to place the mark in the imaging field of view, it is necessary to print the mark at a predetermined position and take an image with predetermined synchronization. In such conventional mark detection, the apparatus configuration is complicated, maintenance is required to obtain accuracy, reliability, and the like, and the apparatus cost is also expensive.
[0004]
The present invention has been made to solve the above problems. The purpose of the present invention is to provide a mark detection device that can detect even a sparse mark in which the distance between dots is large, and has a simple device configuration, easy maintenance, and low device cost. There is.
[0005]
[Means for Solving the Problems]
The above problems are solved by the present invention described below. That is,
A mark detection apparatus according to claim 1 of the present invention is a mark detection apparatus that detects a mark formed by separated dots, and includes a photoelectric sensor and an off-delay device, and the photoelectric sensor is transferred. Detects the dot printed on the article and outputs a detection signal that turns on, and the off delay inputs the detection signal, and does not delay the time when the state of the detection signal changes from off to on An off-delay signal that changes from off to on is output, and when the state of the detection signal changes from on to off, an off-delay signal that delays by a predetermined time and changes from on to off is output. It is.
[0006]
According to the present invention, the photoelectric sensor changes the detection signal to ON only while detecting a dot, but the OFF delay device remains ON for a predetermined time even when the dot is not detected. As a result, if the ON state is maintained beyond the non-detection time between dot detection and dot detection, it is equivalent to the absence of a break between the dots. That is, it can be detected as one mark instead of individual dots. Therefore, it is possible to detect even a sparse mark with a large distance between dots, and it is possible to provide a mark detection apparatus that has a simple apparatus configuration, is easy to maintain, and is low in apparatus cost.
[0007]
A mark detection apparatus according to a second aspect of the present invention is the mark detection apparatus according to the first aspect, further comprising an on-delay device, wherein the on-delay device inputs an off-delay signal, and the state of the off-delay signal is When changing from off to on, an on-delay signal is output that delays by a predetermined time and changes from off to on.When the state of the off-delay signal changes from on to off, the time is not delayed and the signal is turned from on to off. A changing on-delay signal is output. According to the present invention, excessive detection due to the texture of an article other than dots, that is, noise is suppressed, and detection of other marks under the photoelectric sensor is avoided.
[0008]
A mark detection apparatus according to claim 3 of the present invention is the mark detection apparatus according to claim 1 or 2, wherein the mark detection apparatus includes a plurality of the photoelectric sensors and is arranged in the left-right direction so that no gap is generated in the detection region. In addition, a logical sum calculation means is provided, and the logical sum calculation means calculates a logical sum of the on-delay signals corresponding to each of the plurality of photoelectric sensors and outputs a logical sum signal. According to the present invention, it is avoided that the detection spot of the photoelectric sensor is between dots and cannot be detected. Further, it becomes possible to avoid being undetectable due to meandering of the article to be transferred.
[0009]
A mark detection apparatus according to claim 4 of the present invention is the mark detection apparatus according to any one of claims 1 to 3, further comprising synchronization processing means, wherein the synchronization processing means is the article in which the mark has periodicity. When the mark is printed in the predetermined area, only the detection signal of the predetermined area is set as the detection signal to be processed. According to the present invention, detection of other marks is avoided.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described. Here, a printed material will be described as an example of an article. A mark formed by the separated dots is printed on a defective print. Detecting this mark is equivalent to detecting a defective printed material from normal printed materials. An example of a printed material on which marks formed by the separated dots are printed is shown in FIG. The printed matter shown in FIG. 3 is a printed matter on the web, and the same pattern with the circumference of the printing plate in the printing machine as a cycle is repeatedly printed on the web printing paper. Here, the printed material of one cycle is simply called a printed material, and the printed material on the web is simply called a web.
[0011]
In FIG. 3, 101b and 101c are defective print marks, and 201a, 201b, 201c and 201d are other marks. The defective print marks 101b and 101c are printed only on the defective printed matter. As shown in FIG. 3, the defective print marks 101b and 101c are printed only on a defective printed matter having a defective portion in a printed pattern. These defective print marks 101b and 101c are separated from printing by a printing plate, and printing is performed based on a command from a printed material inspection apparatus or the like. For this printing, for example, a dot printer such as an ink jet is used, and printing is performed on printing paper that is transported at high speed. For this reason, the distance between the dots is large and the marks are sparse.
[0012]
On the other hand, as shown in FIG. 3, the other marks 201a, 201b, 201c, and 201d are printed on all printed materials without distinction between normal printed materials and defective printed materials. These other marks 201a, 201b, 201c, and 201d are printed in the same manner as the pattern printing by the printing plate. Both the defective print marks 101b and 101c and the other marks 201a, 201b, 201c, and 201d are printed on blank portions that do not appear in the final product in the printed matter. Since the margins in the printed material are limited, both marks are printed side by side in the web transfer direction (top and bottom direction; the direction of arrow → in FIG. 3).
[0013]
Next, the mark detection apparatus of the present invention for detecting the above-described defective print marks 101b and 101c will be described. An example of the configuration of the mark detection apparatus of the present invention is shown in FIG. In FIG. 1, 1a and 1b are photoelectric sensors, 2a and 2b are amplifier units, 3 is a processing unit, and 4 is a rotary encoder. In the processing unit 3, 31 a and 31 b are off delay circuits, 32 a and 32 b are on delay circuits, 33 is an OR circuit, and 34 is a gate circuit. Reference numeral 101 denotes a defective print mark, and 201 denotes another mark. Note that the defective print mark 101 and the other marks 201 are marks printed on the printed matter shown in FIG. 3 described above, and the arrow → indicates the transport direction of the printed matter.
[0014]
The photoelectric sensors 1a and 1b are installed in the web transfer path so that the blank portion of the printed material is a detection area. The photoelectric sensors 1a and 1b have a structure that can detect small dots with high sensitivity. For example, it is composed of a lens system and a photoelectric element, or a lens system, an optical fiber, and a photoelectric element. In many cases, a light emitting element for illuminating the detection region is included in addition to the configuration. With this configuration, it is possible to set a narrow detection region in the margin.
[0015]
The photoelectric sensors 1a and 1b are connected to the amplifier units 2a and 2b, and an optical signal is converted into an electric signal integrally (the whole can also be called a photoelectric sensor). When the dots printed on the margin are detected in the printed matter to which the photoelectric sensors 1a and 1b are transferred, detection signals that are turned on are output from the amplifier units 2a and 2b. However, the photoelectric sensors 1a and 1b do not distinguish between dots and other marks and dirt. Therefore, just because the detection signal is turned on does not mean that a dot has been detected immediately.
[0016]
As described above, the interval between the dots is separated, and the defective print mark 101 is a sparse mark. The photoelectric sensors 1a and 1b have a narrow detection region so that small dots can be detected with high sensitivity. Therefore, it is necessary to prevent the detection area from being set only in the blank portion between the dots. The mark detection apparatus of the present invention includes a plurality of photoelectric sensors 1a and 1b and amplifier units 2a and 2b. And it arranges in the left-right direction (perpendicular direction to a transfer direction) so that a gap may not arise in those detection fields. In FIG. 1, two photoelectric sensors 1a and 1b and two amplifier units 2a and 2b are shown, but the number is not limited to two.
[0017]
The processing unit 3 receives the detection signals output from the amplifier units 2 a and 2 b and the web transfer signal output from the rotary encoder 4, and performs a process of detecting the print defect mark 101. When the print defect mark 101 is detected, a reject signal is output to the reject device (defective removal device). Regardless of the detection of the print defect mark 101, the total number of printed materials and / or the number of non-defective products in one cycle are output to the number management device.
[0018]
The rotary encoder 4 outputs a web transfer signal to the processing unit 3. The rotary encoder 4 is provided on a rotation shaft such as a plate cylinder or a transfer roller of a printing press that can detect the transfer of the web, and detects its rotation. The rotary encoder 4 is configured to be able to calculate the phase of the printed matter at the position of the photoelectric sensors 1a and 1b along with the web transfer distance based on the transfer signal.
[0019]
Next, the details of the processing in the processing unit 3 will be described. The off delay circuits 31a and 31b receive detection signals output from the amplifier units 2a and 2b of the photoelectric sensors 1a and 1b. When the state of the detection signal changes from off to on, an off-delay signal that changes from off to on is output without delaying the time. Further, when the state of the detection signal changes from on to off, an off-delay signal is output that delays by a predetermined time and changes from on to off. The off-delay circuits 31a and 31b having such a function can be configured by, for example, a monostable multivibrator.
[0020]
The on delay circuits 32a and 32b receive an off delay signal. When the state of the off-delay signal changes from off to on, an on-delay signal that changes from off to on after a predetermined time delay is output. Further, when the state of the off-delay signal changes from on to off, an on-delay signal that changes from on to off is output without delaying the time. The on-delay circuits 32a and 32b having such a function can also be configured by, for example, a monostable multivibrator.
[0021]
Signal processing performed by the above-described off delay circuits 31a and 31b and on delay circuits 32a and 32b will be described with reference to signal waveforms. An example of a signal waveform when the detection signal is off-delayed and on-delayed is shown in FIG. 2A is a detection signal output from the amplifier units 2a and 2b of the photoelectric sensors 1a and 1b, FIG. 2B is an OFF delay signal output from the OFF delay circuits 31a and 31b, and FIG. The ON delay signal output from the ON delay circuits 32a and 32b is shown.
[0022]
As shown in FIG. 2A, the detection signal is irregularly turned on and off in a short time. This detection signal includes a signal indicating detection of a dot of the defective print mark 101 and a signal indicating detection of another mark 201 or dirt.
[0023]
In the off-delay signal, as shown in FIG. 2B, the part of the detection signal that is irregularly turned on and off in a short time is unified to be on. That is, the defective print mark 101 formed by the separated dots is detected as one unseparated mark. This is because the ON state is maintained beyond the non-detection time between the dot detection and the dot detection so as to be equivalent to the case where there is no break between the dots. On the other hand, the ON time is extended in the part of the detection signal that is turned ON / OFF only once.
[0024]
In the on-delay signal, as shown in FIG. 2C, the part of the off-delay signal that is turned on and off is unified to be off. That is, the other mark 201 or the portion indicating the detection of dirt is removed.
[0025]
In this way, by combining the off delay circuits 31a and 31b and the on delay circuits 32a and 32b, the portions of the detection signal that are irregularly repeated on and off in a short time are unified to be on, and the on / off is single-shot. The off-delay signal part is unified off. As a result, the defective print mark 101 portion is detected.
[0026]
The mark detection apparatus of the present invention includes a plurality of photoelectric sensors 1a and 1b and amplifier units 2a and 2b. This is because, as described above, it is necessary to prevent the detection area from being set only in the blank portion between the dots. Not only the photoelectric sensors 1a and 1b and the amplifier units 2a and 2b, but also a plurality of off-delay circuits 31a and 31b and on-delay circuits 32a and 32b that perform signal processing are similarly provided.
[0027]
These outputs, that is, a plurality of ON delay signals, are input by the OR circuit 33 as shown in FIG. The OR circuit 33 performs an OR operation (logical sum operation) of a plurality of input signals. That is, when any one of the plurality of ON delay signals input to the OR circuit 33 is ON, the logical sum signal that is the output of the OR circuit 33 is ON. Also, the logical sum signal that is the output of the OR circuit 33 is turned off only when all of the plurality of on-delay signals input to the OR circuit 33 are turned off.
[0028]
The gate circuit 34 inputs the logical sum signal and the transfer signal output from the rotary encoder 4 described above. In the gate circuit 34, based on the input transfer signal, the detection area of the photoelectric sensors 1a and 1b is an area where the defective mark 101 should be printed on the printed matter, or other area where other marks or the like should be printed Is calculated. When the detection areas of the photoelectric sensors 1a and 1b are areas where the defect mark 101 is to be printed on the printed matter, the gate circuit 34 opens the gate, and the OR signal output from the OR circuit 33 is output outside the gate. To be output.
[0029]
In other words, the logical sum signal that is the output of the OR circuit 33 is set as an effective logical sum signal only when the photoelectric sensors 1a and 1b detect the area where the defect mark 101 is printed on the printed matter. That is, it is assumed that the defective mark 101 is detected only when the gate is opened and the logical sum signal is on. Only then, the gate circuit 34 outputs a reject signal to the reject device (defective device). Regardless of the detection of the print defect mark 101, the gate circuit 34 outputs the total quantity and / or the quantity of non-defective products in one cycle to the quantity management device.
[0030]
【The invention's effect】
As described above, the mark detection apparatus according to claim 1 of the present invention can detect even a sparse mark with a gap between dots, and the apparatus configuration is simple. Thus, a mark detection apparatus that is easy to maintain and that is low in apparatus cost is provided.
Further, according to the mark detection apparatus of the second aspect of the present invention, it is possible to suppress over-detection due to the texture of articles other than dots, that is, noise, and avoid detection of other marks under the photoelectric sensor.
According to the mark detection apparatus of the third aspect of the present invention, it is possible to avoid that the detection spot of the photoelectric sensor is between dots and cannot be detected. In addition, it is possible to avoid being undetectable due to meandering of the article to be transferred.
Further, according to the mark detection apparatus of the fourth aspect of the present invention, detection of other marks can be avoided.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a configuration in a mark detection apparatus of the present invention.
FIG. 2 is a diagram illustrating an example of a signal waveform when an OFF delay and an ON delay of a detection signal are performed.
FIG. 3 is a diagram illustrating an example of a printed matter on which marks formed by separated dots are printed.
[Explanation of symbols]
1a, 1b Photoelectric sensor 2a, 2b Amplifier unit 3 Processing unit 4 Rotary encoder 31a, 31b Off delay circuit 32a, 32b On delay circuit 33 OR circuit 34 Gate circuit 101, 101b, 101c Defective print mark 201, 201a, 201b, 201c, 201d Other marks

Claims (4)

A mark detection device for detecting a mark formed by separated dots, comprising a photoelectric sensor and an off-delay device,
The photoelectric sensor outputs a detection signal that is turned on by detecting the dots printed on the article to be transferred,
The off-delay device inputs the detection signal, and outputs an off-delay signal that changes from off to on without delaying the time when the state of the detection signal changes from off to on, and the state of the detection signal When changing from on to off, an off-delay signal is output that delays by a predetermined time and changes from on to off.
A mark detection apparatus characterized by that. 2. The mark detection apparatus according to claim 1, further comprising an on-delay device that receives an off-delay signal, and is delayed by a predetermined time when the state of the off-delay signal changes from off to on. An on-delay signal that changes from off to on is output, and when the state of the off-delay signal changes from on to off, an on-delay signal that changes from on to off is output without delaying the time. Detection device. 3. The mark detection apparatus according to claim 1, wherein a plurality of the photoelectric sensors are provided, arranged in the left-right direction so as not to generate a gap in the detection area, and further provided with OR operation means, and the OR operation thereof. The means calculates a logical sum of ON delay signals corresponding to each of the plurality of photoelectric sensors and outputs a logical sum signal. The mark detection device according to any one of claims 1 to 3, further comprising synchronization processing means, wherein the synchronization processing means is a mark printed on a predetermined area of the article having periodicity, A mark detection apparatus characterized in that only a detection signal in a predetermined area is a detection signal to be processed.

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