JP2015123658A - Register mark detection unit, adjustment method, multicolor printing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a register mark detection unit which can increase a detection accuracy of a register mark.SOLUTION: A register mark detection unit includes: a light receiving element 25 having a first photo-electric conversion region 25a, a second photo-electric conversion region 25b and a third photo-electric conversion region 25c which have spectral sensitivity characteristics different from one another; a register mark detection section 32 which detects a register mark given onto a web 2 on the basis of a signal from these photo-electric conversion regions; and an output section 41 which outputs each signal from said plural photo-electric conversion regions, which is inputted to the register mark detection section 32, in a visible mode.

Description

  The present invention relates to a register mark detection unit, an adjustment method, and a multicolor printing system.

  There is known a multicolor printing system in which a plurality of printing units are installed along a web conveyance path, a plate cylinder provided in each printing unit is individually driven to rotate, and printing is sequentially performed on the web. In the multi-color printing system, a registration mark printed on a web is detected by each printing unit, and a printing position shift generated between the plate cylinders is controlled based on the detection result.

  As a method for detecting a registration mark, a method is known in which light is applied to a web, the reflected light is received by a sensor such as a photodiode, and detected using a signal from the sensor (for example, Patent Document 1). reference).

JP 05-016337 A

  For example, when the web is cream and the registration mark is light yellow, the detection signal of the registration mark is very small when the contrast between the color of the underlying web and the color of the registration mark is very small. In this case, the influence of noise on the detection signal increases, and the registration mark detection accuracy decreases.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a registration mark detection unit that can improve the detection accuracy of a registration mark.

  In order to solve the above problems, a registration mark detection unit according to an aspect of the present invention is attached to a web based on a light receiving element having a plurality of photoelectric conversion regions having different spectral sensitivity characteristics and signals from the plurality of photoelectric conversion regions. A registration mark detection unit that detects the registered mark, and an output unit that is input to the registration mark detection unit and outputs the signals from the plurality of photoelectric conversion regions in a manner that can be visually recognized.

  According to this aspect, it is possible to output each of the signals from the plurality of photoelectric conversion regions, which are input to the registration mark detection unit that detects the registration mark, in a visible manner.

  Another aspect of the present invention is an adjustment method. This method is an adjustment method of a registration mark detection unit that detects a registration mark attached to a traveling web, and irradiates light to a range through which the registration mark passes, and forms a plurality of photoelectric conversion regions having different spectral sensitivity characteristics. A step of receiving reflected light from the web by the light receiving element, a step of outputting each signal from the plurality of photoelectric conversion regions in a manner that can be visually recognized, a step of acquiring an instruction to adjust the intensity ratio of each signal, and Adjusting the intensity ratio of each signal based on the instructions.

  Note that any combination of the above-described constituent elements, and those obtained by replacing the constituent elements and expressions of the present invention with each other among methods, apparatuses, systems, etc. are also effective as an aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the registration mark detection unit which can improve the detection accuracy of a registration mark can be provided.

1 is a diagram illustrating a configuration of a multicolor printing system according to an embodiment. It is a block diagram which shows the function and structure of the sensor part of FIG. 1, a machine side control part, and the centralized control part. It is a schematic diagram which shows an example of the waveform which the output part output. It is a figure which shows the circuit structure of an adjustment part. It is a figure which shows the circuit structure of the adjustment part of the multicolor printing system which concerns on a modification.

  Hereinafter, the same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are appropriately omitted. In addition, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. Also, in the drawings, some of the members that are not important for describing the embodiment are omitted.

The outline of the multicolor printing system according to the present embodiment is as follows.
In a multicolor printing system, in general, before printing a pattern, adjustment (hereinafter referred to as “preliminary adjustment”) is performed as advance preparation for increasing the registration mark detection accuracy. If the detection accuracy increases, it is possible to accurately correct the printing position shift. Therefore, in the multicolor printing system according to the present embodiment, light is emitted to the region through which the registration mark passes, and the reflected light is received by a light receiving element having a plurality of photoelectric conversion regions having different spectral sensitivity characteristics. And the signal from these several photoelectric conversion area | regions is output in the aspect which can visually recognize each, without combining. For example, output to a display.

  By referring to this output, the user can confirm which photoelectric conversion region the signal from which the S / N ratio is high with respect to the target registration mark. Therefore, it is possible to determine which photoelectric conversion region should be used to detect the registration mark. Then, since the multicolor printing system can be adjusted so as to have sensitivity according to the target registration mark, the detection accuracy of the registration mark can be increased. If printing is performed in such an adjusted state, it is possible to accurately correct the displacement of the printing position that occurs between the printing units. This will be specifically described below.

  FIG. 1 shows a configuration of a multicolor printing system 100 according to the embodiment. The multicolor printing system 100 includes a plurality of printing units 10 and a central control unit 40. Each printing unit 10 includes a plate cylinder 11, an impression cylinder 12, a sensor unit 20, and a machine-side control unit 30. The web 2 is guided along a predetermined conveyance path by the guide roll 4, is pressed against the plate cylinder 11 by the impression cylinder 12, and a color pattern and a registration mark corresponding to the plate cylinder 11 are printed.

  The sensor unit 20 and the machine-side control unit 30 detect a registration mark printed on the web 2 and determine a printing position shift occurring between the plate cylinders 11 based on the detection result. When there is a printing position shift, the machine-side control unit 30 increases or decreases the rotation amount of the plate cylinder 11 to eliminate the shift. The central control unit 40 supports advance adjustment.

  FIG. 2 is a block diagram illustrating functions and configurations of the sensor unit 20, the machine-side control unit 30, and the central control unit 40. In FIG. 2, only one set of the sensor unit 20 and the machine-side control unit 30 is shown for easy understanding, but there are a plurality of sets in the implementation. The sensor unit 20 includes a light source 21, an optical system 22, a light detection element 23, and a signal amplification unit 24. The light source 21 is a white light source. The light source 21 irradiates the web 2 with light. In particular, the light source 21 irradiates light to an area through which the registration mark passes. The reflected light of the light irradiated on the web 2 is collected by the optical system 22 and received by the light receiving element 25 of the light detecting element 23. The optical system 22 is configured using a known technique.

  The light receiving element 25 is an RGB photodiode. The light receiving element 25 has three photoelectric conversion regions, a first photoelectric conversion region 25a, a second photoelectric conversion region 25b, and a third photoelectric conversion region 25c. Each photoelectric conversion region has different spectral sensitivity characteristics. The first photoelectric conversion region 25a has a characteristic with a peak wavelength in the red band, the second photoelectric conversion region 25b has a characteristic with a peak wavelength in the green band, and the third photoelectric conversion region 25c has a peak wavelength in the blue band. It has a characteristic with Each photoelectric conversion region is grounded on the cathode side, converts received light into a current signal, and outputs it to the anode side. The magnitude of the current signal is a magnitude obtained by integrating the product of the received light intensity and the light receiving sensitivity for each wavelength. A current signal from each photoelectric conversion region is converted into a voltage signal by a current-voltage conversion circuit (not shown), and is output to the signal amplifier 24.

  The signal amplification unit 24 includes a first signal amplification unit 24a, a second signal amplification unit 24b, and a third signal amplification unit 24c. The first signal amplifying unit 24a, the second signal amplifying unit 24b, and the third signal amplifying unit 24c have the same ratio of signals from the first photoelectric conversion region 25a, the second photoelectric conversion region 25b, and the third photoelectric conversion region 25c, respectively. Amplify with. In particular, the signal amplifying unit 24 amplifies the signal so as to be easily recognized when a signal is output to a display or the like by an output unit 41 (described later).

  The central control unit 40 includes an output unit 41 and an acquisition unit 42. The output unit 41 outputs a signal from each photoelectric conversion region in a manner that can be visually recognized. In particular, the output unit 41 outputs the signals output from the signal amplifying unit 24 in such a manner that they can be visually recognized without being synthesized. In the present embodiment, the output unit 41 displays the waveform of each signal on a display device such as a display. The output unit 41 may output to a printing device such as a printer.

  FIG. 3 shows an example of a signal waveform output by the output unit 41 when a certain registration mark passes through an area irradiated by the light source 21. In FIG. 3, the horizontal axis represents time, and the vertical axis represents the signal level. Signal 6a, signal 6b, and signal 6c indicate a signal from the first photoelectric conversion region 25a, a signal from the second photoelectric conversion region 25b, and a signal from the third photoelectric conversion region 25c, respectively. In the example shown in FIG. 3, the signal 6a and the signal 6c have a relatively high S / N ratio, and the signal 6b has a relatively low S / N ratio. By referring to this signal waveform, the user can determine from which photoelectric conversion region the register mark should be detected. For example, in the case of FIG. 3, it can be determined that the registration mark should be detected using the signals 6a and 6c having a relatively high S / N ratio. Note that it may be determined that detection may be performed using one of the signal 6a and the signal 6c.

  The acquisition unit 42 acquires input by the user. Specifically, the acquisition unit 42 acquires information that is information to be input to the adjustment unit 31 (described later) and that indicates how much of the signals from each photoelectric conversion region is to be amplified. . The acquisition unit 42 inputs a signal based on the acquired information to the adjustment unit 31.

  The machine-side control unit 30 includes an adjustment unit 31, a registration mark detection unit 32, and a matching unit 33. The adjustment unit 31 is provided between the light detection element 23 and the registration mark detection unit 32. The adjustment unit 31 includes a first adjustment unit 31a, a second adjustment unit 31b, and a third adjustment unit 31c. The adjustment unit 31 adjusts the intensity ratio of the signal from each photoelectric conversion region that is input to the registration mark detection unit 32. Specifically, the signal from each photoelectric conversion region is amplified according to the signal from the acquisition unit 42. For example, when it is determined that the register mark should be detected using signals from the first photoelectric conversion region 25a and the third photoelectric conversion region 25c, and instruction information corresponding to the registration mark is input to the acquisition unit 42, the first mark The adjustment unit 31a amplifies the signal from the first photoelectric conversion region 25a, and the second adjustment unit 31b amplifies the signal from the second photoelectric conversion region 25b.

  FIG. 4 shows a circuit configuration of the first adjustment unit 31a. Since the circuit configurations of the second adjustment unit 31b and the third adjustment unit 31c are substantially the same as the circuit configuration of the first adjustment unit 31a, the circuit configuration of the first adjustment unit 31a will be described as a representative here. The first adjustment unit 31 a includes a fixed resistor 34, an amplifier 35, and a variable resistor 36 connected to the output terminal of the amplifier 35. The variable resistor 36 can change its resistance value in accordance with a signal input from the outside (here, a signal input from the acquisition unit 42). The variable resistor 36 is, for example, a digital potentiometer. The first adjustment unit 31a amplifies the signal at a ratio k = R2 / R1 between the resistance value R1 of the fixed resistor 34 and the resistance value R2 of the variable resistor 36. Therefore, the signal amplification degree can be changed by changing the resistance value R2 of the variable resistor 36. Returning to FIG.

  The registration mark detection unit 32 detects a registration mark attached to the web 2 based on a signal output from the adjustment unit 31. The registration mark detection unit 32 combines the signals output from the adjustment units of the first adjustment unit 31a, the second adjustment unit 31b, and the third adjustment unit 31c, compares the signal intensity with a predetermined threshold, When the intensity exceeds the threshold, it is determined that the mark is a register mark. As described above, since the signal having a high S / N ratio among the signals from the respective photoelectric conversion regions is amplified by the adjustment unit 31, the S / N ratio of a signal obtained by combining them is naturally high. Therefore, the registration mark detection unit 32 can detect the registration mark with relatively high accuracy.

  A detection result by the register mark detection unit 32 is input to the matching unit 33. Based on the detection result, the matching unit 33 determines whether there is a printing position shift between the plate cylinders 11, that is, whether there is a registration shift. If there is a misregistration, a correction signal is output to the drive motor (not shown) or side layout (not shown) of the printing unit 10 in which the misregistration occurs. The drive motor or sidelay drives the plate cylinder 11 so that the misregistration is corrected based on the correction signal. The drive motor adjusts the misregistration of the web 2 in the running direction, and the sidelay adjusts the misregistration of the web 2 in the width direction.

The operation of the pre-adjustment process of the multicolor printing system configured as described above will be described.
The light source 21 of the sensor unit 20 irradiates light to the region through which the registration mark passes, and the light detection element 23 receives the reflected light from the web 2. Each photoelectric conversion region of the light detection element 23 outputs a signal corresponding to the received light. The output unit 51 of the central control unit 40 displays these signals on the display without combining them. The user refers to the waveform of each signal displayed on the display when a certain register mark passes, and in order to detect the register mark, that is, to increase the detection accuracy of the register mark, Determine whether to use the signal from the transform domain. The adjustment unit 31 receives a signal based on the result of the determination.
The printing unit 10 prints a predetermined pattern on the web 2 by the plate cylinder 11 with the adjustment unit 31 adjusted in this way.

  According to the multicolor printing system 100 according to the present embodiment, signals from the respective photoelectric conversion regions can be output in such a manner that each can be visually recognized. Therefore, the user can determine which photoelectric conversion region should be used for detection for each register mark by referring to this output. As a result, the registration mark detection accuracy can be increased.

  Further, according to the multicolor printing system 100 according to the present embodiment, the adjustment unit 31 can be adjusted by a signal from the outside. Therefore, the user does not need to move to each machine-side control unit 30 when adjusting the adjustment unit 31. Further, the adjustment unit can be adjusted by a relatively simple operation of inputting a predetermined signal. Therefore, the burden on the user is reduced.

  The multicolor printing system according to the embodiment has been described above. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there. A modification is shown below.

(Modification 1)
Although the case where the light receiving element 25 is an RGB photodiode having three photoelectric conversion regions has been described in the embodiment, the present invention is not limited to this. The number of photoelectric conversion regions may be two or four or more. That is, the number of photoelectric conversion regions may be two or more. The light receiving element 25 may be other than the RGB photodiode. In these cases, the degree of freedom in design increases.

(Modification 2)
In the embodiment, the case where the sensor unit 20 receives the reflected light from the web 2 has been described. However, the present invention is not limited to this. For example, the sensor unit 20 may be configured to receive the transmitted light from the web 2. Good.

(Modification 3)
In the embodiment, the case where the machine-side control unit 30 includes the adjustment unit 31 has been described, but the present invention is not limited to this. The sensor unit 20 may have the function of the adjustment unit 31.

(Modification 4)
The central control unit 40 may include a storage unit that stores information input to the adjustment unit 31 of the machine-side control unit 30. If the web 2 is the same and the color of the target match mark is the same, the instruction information to be input to the adjustment unit 31 can be reused. In this case, prior adjustment is unnecessary, and the burden on the user is reduced. In addition, since the work time can be reduced accordingly, productivity is improved.

(Modification 5)
FIG. 5 shows a circuit configuration of the first adjustment unit 131a of the machine-side control unit of the multicolor printing system according to the modification. The first adjustment unit 131a corresponds to the first adjustment unit 31a. In the first adjustment unit 131a, instead of a variable resistor, a plurality of fixed resistors 136_1 to 136_n (n is an arbitrary integer of 2 or more) connected in parallel and in series with the fixed resistors 136_1 to 136_n, respectively. And a switch 137 connected to. Amplification by the adjustment unit 131 can be adjusted by switching the switch 137 in accordance with an instruction from the outside and changing the resistance connected to the amplifier circuit.

  Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present invention. The new embodiment generated by the combination has the effects of the combined embodiment and the modified examples.

  In addition, it should be understood by those skilled in the art that the functions to be fulfilled by the constituent elements described in the claims are realized by the individual constituent elements shown in the embodiments and the modified examples or by their linkage. . For example, the registration mark detection unit described in the claims may be realized by cooperation of the light detection element 23, the registration mark detection unit 32, the output unit 41, and the adjustment unit 31.

  2 web, 10 printing unit, 11 plate cylinder, 12 impression cylinder, 20 sensor unit, 21 light source, 23 light detection element, 24 signal amplification unit, 25 light receiving element, 25a first photoelectric conversion region, 25b second photoelectric conversion region, 25c 3rd photoelectric conversion area, 30 machine side control part, 31 adjustment part, 31a 1st adjustment part, 31b 2nd adjustment part, 31c 3rd adjustment part, 32 register mark detection part, 33 matching part, 34 fixed resistance, 35 Amplifier, 36 variable resistor, 40 central control unit, 41 output unit, 42 acquisition unit, 100 multicolor printing system, 131 adjustment unit.

Claims (6)

A light receiving element having a plurality of photoelectric conversion regions having different spectral sensitivity characteristics;
A registration mark detection unit that detects a registration mark attached to the web based on signals from the plurality of photoelectric conversion regions;
A registration mark detection unit, comprising: an output unit that outputs the signals from the plurality of photoelectric conversion regions, which are input to the registration mark detection unit, in a manner in which the signals can be visually recognized.   The adjustment unit that is provided between the plurality of photoelectric conversion regions and the registration mark detection unit and adjusts an intensity ratio of a signal from each of the plurality of photoelectric conversion regions. Register mark detection unit.   The register mark detection unit according to claim 2, wherein the adjustment unit is configured to adjust an intensity ratio of each signal based on an external signal.   The register mark detection unit according to claim 3, wherein the adjustment unit includes a variable resistor whose resistance value can be changed by a signal from the outside.   A multicolor printing system comprising the register mark detection unit according to claim 1. An adjustment method of a registration mark detection unit for detecting a registration mark attached to a traveling web,
Irradiating light to a range through which the registration mark passes, and receiving reflected light from the web by a light receiving element having a plurality of photoelectric conversion regions having different spectral sensitivity characteristics;
Outputting each signal from the plurality of photoelectric conversion regions in a visible manner;
Obtaining an instruction to adjust the intensity ratio of each signal;
Adjusting the intensity ratio of each signal based on the acquired instruction.

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