JP2017159602A - Sensor, register control unit, multicolor printing system and detection method of register mark - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique which can improve detection accuracy of a register mark.SOLUTION: A register control unit 20 of a multicolor printing system comprises: a light receiving element 34 which includes three photo-electric conversion regions having different spectral sensitivity characteristics; a register mark detection unit 44 which detects a register mark 6 arranged in a base material 2 on the basis of signals from the three photo-electric conversion regions; and a signal inversion unit 35 arranged between the light receiving element 34 and the register mark detection unit 44 and which inverts signals from the three photo-electric conversion regions with respect to respective reference values.SELECTED DRAWING: Figure 3

Description

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

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

  As a technique for detecting a registration mark, a technique is known in which light is applied to a ground, the reflected light is received by a sensor, and detected using a signal output from the sensor (see, for example, Patent Document 1).

JP 05-016337 A

  In a multi-color printing system, if the registration mark detection accuracy is increased, it is possible to accurately correct the deviation of the printing position.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique capable of increasing the registration mark detection accuracy.

  In order to solve the above problems, a register control unit according to an aspect of the present invention is attached to a ground 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 for detecting a registration mark, and a signal inversion for inverting a signal from each of the plurality of photoelectric conversion regions with respect to each reference value provided between the light receiving element and the registration mark detection unit A section.

  Another aspect of the present invention is a registration mark detection method. This method irradiates light in a range through which a registration mark passes, and receives light from the ground by 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. Among them, the method includes a step of inverting a signal designated from the outside with respect to a reference value, and a step of detecting a register mark attached to the ground based on signals from a plurality of photoelectric conversion regions.

  Yet another embodiment of the present invention is a sensor. This sensor is used in a multicolor printing system, and includes a light receiving element having a plurality of photoelectric conversion regions having different spectral sensitivity characteristics, an external terminal for outputting signals of the plurality of photoelectric conversion regions to the outside, An inversion unit that is provided between the element and the external terminal and inverts a signal designated from outside among a plurality of photoelectric conversion regions based on a predetermined value.

  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.

  According to the present invention, the registration mark detection accuracy can be increased.

It is a figure which shows the waveform of the signal output from the light receiving element of the registration control unit which concerns on embodiment. It is a figure which shows the structure of the multicolor printing system provided with the registration control unit which concerns on embodiment. It is a block diagram which shows the function and structure of the register control unit of FIG. It is a block diagram which shows the function and structure of the register control unit 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.

  Before describing the present invention in detail, an outline will be described. The embodiment of the present invention is a multicolor printing system including a register control unit. The register control unit includes a light receiving element having three photoelectric conversion regions having different spectral sensitivity characteristics. The registration control unit irradiates the base with light, receives the reflected light by the light receiving element, and detects a registration mark attached to the base using a signal output from the light receiving element.

  By the way, in a multicolor printing system, an adjustment (hereinafter, referred to as “preliminary adjustment”) is generally performed to increase the registration mark detection accuracy before printing a picture. If the detection accuracy increases, it is possible to accurately correct the printing position shift.

  In the present embodiment, in the pre-adjustment, the signals output from the three photoelectric conversion regions of the light receiving element are output in such a manner that they can be visually recognized without being synthesized. FIG. 1 shows the waveform of the signal thus output. Signals 4a, 4b, and 4c indicate waveforms of signals output from the first photoelectric conversion region, the second photoelectric conversion region, and the third photoelectric conversion region, respectively. In the example of FIG. 1, the signal 4a and the signal 4b have a signal strength of the registration mark larger than that of the ground, and the signal 4c has a signal strength of the registration mark smaller than that of the ground. That is, the signals output from the three photoelectric conversion regions do not have the same magnitude relationship between the signal strengths of the background and the registration mark. Such a situation may occur depending on the combination of the base color and the register mark color. In this case, when the signals output from the three photoelectric conversion regions are combined, the intensity difference between the signals of the background and the register mark is canceled out. This can lead to a decrease in registration mark detection accuracy.

  On the other hand, the register control unit according to the present embodiment reverses the signals from the three photoelectric conversion regions with respect to the respective reference values (for example, the intermediate value between the maximum value and the minimum value of the signal). The signal inversion unit is further provided. By inverting the signal from the specific photoelectric conversion area by the signal inversion unit, the signals from the three photoelectric conversion areas have the same magnitude relationship between the signal intensity of the background and the register mark, and when they are combined, The difference in signal strength between the register marks is not canceled out.

  In the pre-adjustment, the user specifies the photoelectric conversion region outputting the signal to be inverted with reference to the waveform of the output signal as shown in FIG. 1, and the signal from the specified photoelectric conversion region is inverted. Set the signal inversion part so that the part is inverted. In the example of FIG. 1, for example, the signal inversion unit may be set so that the signal inversion unit inverts the signal 4c from the third photoelectric conversion region as indicated by a dotted line. As a result, the signals from the three photoelectric conversion areas have the same magnitude relationship between the signal intensity of the background and the registration mark, and even if they are combined, the difference in signal intensity between the background and the registration mark is not canceled, and the registration mark detection accuracy Will increase. This will be specifically described below.

  FIG. 2 shows a configuration of a multicolor printing system 100 including a register control unit according to the embodiment. The multicolor printing system 100 includes a first printing unit 10 </ b> A, a second printing unit 10 </ b> B (hereinafter collectively referred to as “printing unit 10”), and a register control unit 20. Each printing unit 10 includes a plate cylinder 11 and an impression cylinder 12. The foundation 2 is guided along a predetermined conveyance path by the guide roll 4 and is pressed against the plate cylinder 11 by the impression cylinder 12. A pattern and a registration mark of a color corresponding to the plate cylinder 11 are printed on the base 2. In particular, the first registration mark 6A (not shown in FIG. 2) is printed on the base 2 in the first printing unit 10A, and the second registration mark 6B (not shown in FIG. 2) is printed on the second printing unit 10B. Hereinafter, the first register mark 6A and the second register mark 6B are collectively referred to as “register mark 6”.

  The register control unit 20 includes a sensor 30 and a control unit 40. The sensor 30 and the control unit 40 detect the first registration mark 6A and the second registration mark 6B, and determine a registration deviation between the first printing unit 10A and the second printing unit 10B. When the registration deviation has occurred, the control unit 40 increases or decreases the rotation amount of the plate cylinder 11 of the second printing unit 10B to eliminate the deviation.

  FIG. 3 is a block diagram showing the function and configuration of the register control unit 20. The sensor 30 includes a first sensor unit 31a and a second sensor unit 31b. The first sensor unit 31a and the second sensor unit 31b are arranged at an interval L. This interval L corresponds to the distance between the first registration mark 6A and the second registration mark 6B when there is no misregistration. Each of the first sensor unit 31a and the second sensor unit 31b includes a light source 32, an optical system 33, a light receiving element 34, and a signal inversion unit 35. The light source 32 is a white light source. The light source 32 irradiates the base 2 with light. In particular, the light source 32 irradiates light to an area through which the registration mark 6 passes. The reflected light of the light irradiated on the base 2 is collected by the optical system 33 and received by the light receiving element 34. The optical system 33 is configured using a known technique.

  The light receiving element 34 is an RGB photodiode. The light receiving element 34 has three photoelectric conversion regions, a first photoelectric conversion region 34a, a second photoelectric conversion region 34b, and a third photoelectric conversion region 34c. Each photoelectric conversion region has different spectral sensitivity characteristics. The first photoelectric conversion region 34a has a characteristic having a peak wavelength in the red band, the second photoelectric conversion region 34b has a characteristic having a peak wavelength in the green band, and the third photoelectric conversion region 34c has a characteristic having 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 output to the signal inversion unit 35.

  The signal inverter 35 includes a first signal inverter 35a, a second signal inverter 35b, and a third signal inverter 35c. In the present embodiment, the first signal inversion unit 35a, the second signal inversion unit 35b, and the third signal inversion unit 35c are configured by circuits. In accordance with the inversion instruction from the control unit 40, the first signal inversion unit 35a outputs the signal output from the first photoelectric conversion region 34a as it is or inverts the instructed reference value. Similarly, the second signal inversion unit 35b and the third signal inversion unit 35c output the signals output from the second photoelectric conversion region 34b and the third photoelectric conversion region 34c as they are, respectively, in accordance with instructions from the control unit 40. Inverts and outputs the specified reference. For example, when instructed to invert the signal output from the third photoelectric conversion region 34c, the third signal inversion unit 35c inverts and outputs the signal from the third photoelectric conversion region 34c. On the other hand, the first signal inversion unit 35a and the second signal inversion unit 35b respectively output the signals from the first photoelectric conversion region 34a and the second photoelectric conversion region 34b as they are.

  The control unit 40 includes an output control unit 41, an acquisition unit 42, a setting unit 43, a first registration mark detection unit 44a, and a second registration mark detection unit 44b (hereinafter collectively referred to as “register mark detection unit 44”). And a matching section 45.

  The output control part 41 outputs the signal output from each photoelectric conversion area | region of the 1st sensor part 31a and the 2nd sensor part 31b in the aspect which can be visually recognized. In particular, the output control unit 41 outputs the signals output from the first sensor unit 31a and the second sensor unit 31b in a manner that allows them to be visually recognized without being synthesized. Specifically, the output control unit 41 outputs each of the signal output from the first sensor unit 31a and the signal output from the second sensor unit 31b as shown in FIG. In the present embodiment, the output control unit 41 displays the waveform of each signal on a display device (not shown) such as a display. The output control unit 41 may output to a printing device such as a printer.

  The acquisition unit 42 acquires input information from the user via an input device (not shown). The input information includes, for example, information indicating from which photoelectric conversion region the signal is inverted with respect to which reference. The setting unit 43 sends an inversion instruction including a reference value to the signal inversion unit 35 based on information included in the input information acquired by the acquisition unit 42. For example, when the acquisition unit 42 acquires input information indicating that a signal from the third photoelectric conversion region 34c is inverted, the setting unit 43 sends an inversion instruction including a reference value to the third signal inversion unit 35c.

  The first registration mark detection unit 44a detects the first registration mark 6A attached to the base 2 based on the signal output from the first sensor unit 31a. The first registration mark detection unit 44a combines the signals output from the first sensor unit 31a, compares the signal intensity of the combined signal with a predetermined detection threshold value, and registers when the signal intensity exceeds the detection threshold value. It is determined that it is a mark. The second registration mark detection unit 44b detects the second registration mark 6B attached to the base 2 based on the signal output from the second sensor unit 31b. The second registration mark detection unit 44b is configured in the same manner as the first registration mark detection unit 44a.

  Detection results from the first registration mark detection unit 44a and the second registration mark detection unit 44b are input to the matching unit 45. Based on these detection results, the matching unit 45 determines whether there is a printing position shift between the plate cylinders 11, that is, whether there is a registration shift. As described above, the first sensor portion 31a and the second sensor portion 31b are arranged at the interval L, and the first registration mark 6A and the second registration mark 6B when there is no misregistration are also printed at the interval L. Therefore, when there is no misregistration, the first registration mark 6A and the second registration mark 6B are detected at substantially the same timing. Thus, the first time when the first registration mark detection unit 44a detects the first registration mark 6A and the second time when the second registration mark detection unit 44b detects the second registration mark 6B are substantially the same. When they are the same, the matching unit 45 determines that there is no registration error. On the other hand, when the first time and the second time are different, the matching unit 45 determines that there is a misregistration by the amount obtained by multiplying the difference between the first time and the second time by the feed speed of the base 2.

  If there is a misregistration, the matching unit 45 outputs a correction signal to, for example, a drive motor (not shown) or a sidelay (not shown) of the second printing unit 10B. 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 base 2 in the running direction, and the side array adjusts the misregistration of the base 2 in the width direction.

An operation in the pre-adjustment of the multicolor printing system configured as described above will be described.
The light source 32 irradiates the region through which the registration mark passes, and the light receiving element 34 receives the reflected light from the base 2. Each photoelectric conversion region of the light receiving element 34 outputs a signal corresponding to the received light. The output control unit 41 displays these signals on the display without combining them. The user refers to the waveform of each signal displayed on the display when the registration mark passes, and determines which photoelectric conversion region should be inverted. For example, the user inverts a signal that is smaller than the signal strength of the background. In addition, for example, the user may determine that a signal whose magnitude relationship with the signal strength of the background is opposite by one should be inverted. That is, if there are many signals with a register mark signal strength greater than that of the background, the signal with a lower registration mark signal strength than the background is inverted, and if there are many signals with a register mark signal strength lower than the background, Alternatively, it may be determined that a signal having a higher registration mark signal strength should be inverted. Based on the determination, the user inputs input information including a signal to be inverted and a reference value for inverting the signal. As the reference value, for example, an intermediate value between the maximum value and the minimum value of the signal intensity to be inverted displayed on the display, the signal intensity of the background, and other values are input.

  The acquisition unit 42 acquires input information. The setting unit 43 sends an inversion instruction to the signal inversion unit 35 based on the input information. Thereafter, the signal inverting unit 35 outputs or inverts the signal from each photoelectric conversion region as it is according to the instruction from the setting unit 43.

  According to the register control unit 20 and the multi-color printing system 100 including the register control unit 20 according to the present embodiment described above, the signals from the three photoelectric conversion regions have the same magnitude relationship between the signal strengths of the background and the register mark. When this is combined, the difference in signal strength between the ground and the register mark is not canceled. As a result, the registration mark detection accuracy increases.

  The multicolor printing system including the register control unit 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.

(Modification 1)
FIG. 4 is a block diagram showing the function and configuration of the register control unit 120 according to the modification. FIG. 4 corresponds to FIG. The register control unit 120 includes a sensor 130 and a control unit 140.

  The sensor 130 includes a first sensor unit 131a and a second sensor unit 131b. Each of the first sensor unit 131a and the second sensor unit 131b includes a light source 32, an optical system 33, and a light receiving element. The control unit 140 includes a signal inversion unit 35, an output control unit 41, an acquisition unit 42, a setting unit 43, a first registration mark detection unit 44a, a second registration mark detection unit 44b, a matching unit 45, including. That is, in the present modification, the signal inverting unit 35 is included in the control unit 140 instead of the sensor 130.

  According to this modification, the same effects as the effects exhibited by the multicolor printing system 100 including the register control unit 20 according to the embodiment are exhibited.

(Modification 2)
In the embodiment and the modification described above, the case where the signal inversion unit is configured by a circuit has been described. However, the present invention is not limited to this, and the signal inversion unit may be configured by software.

  In this case, the signal inverting unit may invert the signal from the photoelectric conversion region instructed by the setting unit 43 with respect to the instructed reference value and output the signal, as in the case where the circuit is constituted by a circuit.

  In addition, the signal inversion unit may determine a signal to be automatically inverted without setting the unit 43 and thus an instruction from the user, and invert the signal from the photoelectric conversion region outputting the signal. Specifically, the signal inversion unit determines that a signal (the signal 4c in the case of FIG. 1) whose registration mark signal intensity is lower than that of the background is a signal to be inverted, and outputs the signal. The signal from (in the case of FIG. 1, the third photoelectric conversion region) may be inverted. In addition, the signal inversion unit determines that signals having a signal strength of the register mark larger than that of the background (in the case of FIG. 1, the signal 4a and the signal 4b) are signals to be inverted, and outputs a photoelectric conversion region ( In the case of FIG. 1, signals from the first photoelectric conversion region and the second photoelectric conversion region may be inverted. In addition, when there are many signals whose register mark signal intensity is higher than that of the background, the signal inversion unit determines that the signal whose register mark signal intensity is lower than that of the background should be inverted, and the signal of the register mark is lower than that of the background. When there are many signals with low intensity, it may be determined that a signal whose register mark signal intensity is higher than that of the background is to be inverted. For example, in the case of FIG. 1, since there are many signals whose register mark signal intensity is higher than that of the background, the signal 4c that is a signal whose register mark signal intensity is lower than that of the background may be determined as a signal to be inverted. In any case, the signal inverting unit is configured to determine a signal to be inverted so that the magnitude relationship between the signal strengths of the background and the registration mark is aligned, and to invert the signal from the photoelectric conversion region outputting the signal. It only has to be done.

(Modification 3)
Although not particularly mentioned in the embodiment and the above-described modification, the sensor or the control unit may include an adjustment unit for adjusting the intensity ratio of the signal from each photoelectric conversion region. For example, the adjustment unit may be configured to amplify the signal instructed by the setting unit 43. This makes it possible to amplify only a signal with a high S / N ratio, and the registration mark detection accuracy is increased.

  In addition, the sensor unit or the control unit may be configured to select a signal output to the registration mark detection unit 44. Specifically, the sensor unit or the control unit is disconnected from the state where each photoelectric conversion region and the registration mark detection unit are electrically connected to each path between each photoelectric conversion region and the registration mark detection unit 44. A switch for switching between the two states may be included. As a result, only a signal having a high S / N ratio can be output to the register mark detection unit 44, that is, it can be used for register mark detection, and the register mark detection accuracy is increased.

(Modification 4)
In the embodiment, the case where the multicolor printing system 100 includes the two printing units of the first printing unit 10A and the second printing unit 10B has been described, but the present invention is not limited to this. The multicolor printing system 100 may include n (≧ 3) printing units. In this case, the register control unit 20 may include n−1 sensors and a machine-side control unit.

(Modification 5)
In the embodiment, the case where the light receiving element 34 is an RGB photodiode having three photoelectric conversion regions has been described. However, the present invention is not limited to this.

  The light receiving element 34 may be an RGB photodiode having two or four or more photoelectric conversion regions. The light receiving element 34 may be other than the RGB photodiode. In these cases, the degree of freedom in design increases.

(Modification 6)
In the embodiment, the case where the first sensor unit 31a and the second sensor unit 31b receive reflected light from the base 2 has been described. However, the present invention is not limited to this, and for example, the first sensor unit 31a and the second sensor unit 31b. May be configured to receive transmitted light from the base 2.

  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.

  20 register control unit, 30 sensor, 31a first sensor unit, 31b second sensor unit, 35 signal inversion unit, 40 control unit, 41 output control unit, 42 acquisition unit, 43 setting unit, 44 register mark detection unit, 45 register 100 multi-color printing system.

Claims (9)

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 a base based on signals from the plurality of photoelectric conversion regions;
A signal inversion unit provided between the light receiving element and the registration mark detection unit and configured to invert a signal from each of the plurality of photoelectric conversion regions with respect to each reference value; Register control unit to be.   The register control unit according to claim 1, wherein the signal inversion unit is configured to invert a signal instructed from the outside among signals from the plurality of photoelectric conversion regions.   2. The register control unit according to claim 1, wherein the signal inversion unit inverts the signals from the plurality of photoelectric conversion regions so that the magnitude relationship of the signal intensity of the register mark with respect to the background is uniform.   The signal inversion unit inverts a signal having a signal strength of the register mark lower than that of the background when the signal from each of the plurality of photoelectric conversion regions has a larger signal strength of the register mark than that of the background. 4. The registration control unit according to claim 3, wherein when there are many signals having a low registration mark signal strength, a signal having a higher registration mark signal strength than the background is inverted.   The register control unit according to claim 1, wherein the signal inversion unit inverts a signal having a signal strength of a register mark smaller than that of a base among signals from the plurality of photoelectric conversion regions.   6. The register control unit according to claim 1, wherein the reference value is an intermediate value between a maximum value and a minimum value of signal strength.   A multicolor printing system comprising the register control unit according to claim 1. Irradiating light to a range through which the registration mark passes, and receiving light from the ground by a light receiving element having a plurality of photoelectric conversion regions having different spectral sensitivity characteristics;
Inverting a signal designated from the outside with respect to a reference value among signals from the plurality of photoelectric conversion regions;
Detecting a registration mark attached to a base based on signals from the plurality of photoelectric conversion regions. A sensor used in a multicolor printing system,
A light receiving element having a plurality of photoelectric conversion regions having different spectral sensitivity characteristics;
An external terminal for outputting the signals of the plurality of photoelectric conversion regions to the outside;
An inversion unit that is provided between the light receiving element and the external terminal and inverts a signal designated from the outside based on a predetermined value among signals from the plurality of photoelectric conversion regions. Sensor.

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