JP6548909B2 - Registration control unit, multi-color printing system including the registration control unit, and method of detecting a registration mark - Google Patents

Description

  The present invention relates to a register control unit, a multi-color printing system comprising a register control unit, and a method for detecting a register mark.

  There is known a multi-color 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 a web. In the multi-color printing system, register marks printed on the web are detected in each printing unit, and the deviation of the printing position generated between the plate cylinders is controlled based on the detection result.

  As a method of detecting a registration mark, there is known a method of irradiating a web with light, receiving the reflected light by a sensor, and detecting using a signal from the sensor (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 05-016337

  For example, when the web is cream colored and the registration mark is light yellow, etc., when the contrast between the color of the underlying web and the color of the registration mark is very small, the influence of noise on the detection signal becomes large and the registration mark Detection accuracy is reduced.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a register control unit capable of enhancing detection accuracy of a register mark.

  In order to solve the above problems, the register mark detection unit according to an embodiment of the present invention acquires the color of the background and the color of the register mark to be received by the light receiving element having a plurality of photoelectric conversion regions having different spectral sensitivity characteristics. And an adjustment unit configured to adjust the intensity ratio of the signal from each photoelectric conversion region based on the color of the background and the color of the register mark acquired by the acquisition unit.

  It is to be noted that any combination of the above-described constituent elements, or one obtained by replacing the constituent elements and expressions of the present invention among methods, apparatuses, systems, etc. is also effective as an aspect of the present invention.

  According to the present invention, it is possible to provide a register control unit capable of enhancing detection accuracy of a register mark.

It is a figure showing composition of a multi-color printing system concerning an embodiment. It is a block diagram which shows the function and structure of the register control unit of FIG. FIGS. 3A and 3B are graphs showing an example of detection results by the first register mark detection unit and the second register mark detection unit. It is a figure which shows the data structure of a correspondence holding part. FIGS. 5A and 5B are graphs showing another example of detection results by the first register mark detection unit and the second register mark detection unit.

  Hereinafter, the same or equivalent constituent elements, members, and steps shown in the drawings are denoted by the same reference numerals, and duplicating descriptions will be appropriately omitted. In addition, dimensions of members in each drawing are shown appropriately enlarged or reduced for easy understanding. In each drawing, a part of members which are not important in describing the embodiment is omitted and displayed.

  FIG. 1 shows the configuration of a multi-color printing system 100 according to an embodiment. The multicolor printing system 100 includes a first printing unit 10A, a second printing unit 10B (hereinafter, also 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 web 2 is guided by a guide roll 4 along a predetermined transport path, and pressed against the plate cylinder 11 by an impression cylinder 12. On the web 2, a design of a color corresponding to the plate cylinder 11 and a register mark are printed. In particular, in the web 2, in each of the first printing unit 10A and the second printing unit 10B, the first register mark 6A and the second register mark 6B not shown in FIG. 1 (hereinafter collectively referred to as “register mark 6”) Each of the calls is printed.

  The register control unit 20 includes a sensor 30, a machine-side control unit 40, and a central control unit 50. The sensor 30 and the machine-side control unit 40 detect the first register mark 6A and the second register mark 6B, and determine the misalignment between the first print unit 10A and the second print unit 10B. If a misregistration has occurred, the machine-side control unit 40 increases or decreases the amount of rotation of the plate cylinder 11 of the second printing unit 10B to eliminate the deviation. The central control unit 50 supports the detection of the register mark by the machine control unit 40.

  FIG. 2 is a block diagram showing the function and configuration of the register control unit 20. As shown in FIG. The sensor 30 includes a first photoelectric sensor unit 31a, a second photoelectric sensor unit 31b, a first imaging unit 37a, and a second imaging unit 37b. The first photoelectric sensor unit 31 a and the second photoelectric sensor unit 31 b are disposed at an interval L. The interval L corresponds to the distance between the first register mark 6A and the second register mark 6B when no register deviation occurs. Each of the first photoelectric sensor unit 31 a and the second photoelectric sensor unit 31 b includes a light source 32, an optical system 33, a light detection element 34, and a signal amplification unit 35. The light source 32 is a white light source. The light source 32 irradiates the web 2 with light. In particular, the light source 32 illuminates the area through which the registration mark 6 passes. The reflected light of the light irradiated to the web 2 is collected by the optical system 33 and is received by the light receiving element 36 of the light detecting element 34. The optical system 33 is configured using a known technique.

  The light receiving element 36 is an RGB photodiode. The light receiving element 36 has three photoelectric conversion regions of a first photoelectric conversion region 36a, a second photoelectric conversion region 36b, and a third photoelectric conversion region 36c. Each photoelectric conversion region has different spectral sensitivity characteristics. The first photoelectric conversion region 36a has a characteristic having a peak wavelength in the red band, the second photoelectric conversion region 36b has a characteristic having a peak wavelength in the green band, and the third photoelectric conversion region 36c has a peak wavelength in the blue band. Have characteristics. Each photoelectric conversion region is grounded on the cathode side, converts the 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 intensity of the received light and the photosensitivity for each wavelength. The 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 amplification unit 35.

  The signal amplification unit 35 includes a first signal amplification unit 35a, a second signal amplification unit 35b, and a third signal amplification unit 35c. The first signal amplification unit 35a, the second signal amplification unit 35b, and the third signal amplification unit 35c have the same ratio of the signals from the first photoelectric conversion region 36a, the second photoelectric conversion region 36b, and the third photoelectric conversion region 36c, respectively. Amplify with

  The first imaging unit 37a captures an image of the area sensed by the first photoelectric sensor unit 31a. That is, the first imaging unit 37a captures an image of the web 2 and the first register mark 6A. The second imaging unit 37 b captures an image of the area sensed by the second photoelectric sensor unit 31 b. That is, the second imaging unit 37b images the web 2 and the second register mark 6B. The first imaging unit 37 a and the second imaging unit 37 b send the acquired captured image to the central control unit 50.

  The machine-side control unit 40 includes a first adjustment unit 41a and a second adjustment unit 41b (hereinafter collectively referred to as “adjustment unit 41”), a first register mark detection unit 42a and a second register mark detection unit 42b ( Hereinafter, it is collectively referred to as "foreign mark detection unit 42" and a registration unit 43. The first adjustment unit 41a is provided between the first photoelectric sensor unit 31a and the first register mark detection unit 42a. The first adjustment unit 41a adjusts the intensity ratio of the signal from each photoelectric conversion area of the light receiving element 36 of the first photoelectric sensor unit 31a. Specifically, the first adjustment unit 41a is a signal from the photoelectric conversion area instructed by the concentration control unit 50, and amplifies each signal having a high S / N ratio as described later, thereby performing each photoelectric conversion. Adjust the intensity ratio of the signal from the area. The second adjustment unit 41 b is provided between the second photoelectric sensor unit 31 b and the second register mark detection unit 42 b. The second adjustment unit 41 b is configured in the same manner as the first adjustment unit 41 a.

  The first register mark detection unit 42a detects the first register mark 6A attached to the web 2 based on the signal output from the first adjustment unit 41a. The first register mark detection unit 42a combines the signals output from the first adjustment unit 41a, compares the signal strength of the combined signal with a predetermined detection threshold, and when the signal strength exceeds the detection threshold, the registration mark is detected. It is determined that it is a mark. Among the signals from the respective photoelectric conversion regions, the signal having a high S / N ratio is amplified by the first adjustment unit 41a, so the S / N ratio of the signal obtained by combining them is naturally high. Therefore, the first register mark detection unit 42a can detect the register mark with relatively high accuracy. The second register mark detection unit 42 b detects a second register mark 6 B attached to the web 2 based on the signal output from the second adjustment unit 41 b. The second register mark detection unit 42b is configured in the same manner as the first register mark detection unit 42a.

  Detection results from the first register mark detection unit 42 a and the second register mark detection unit 42 b are input to the registration unit 43. The registration unit 43 determines, based on the detection results, the deviation of the printing position generated between the plate cylinders 11, that is, the presence or absence of the registration deviation. FIGS. 3A and 3B are graphs showing an example of detection results by the first register mark detection unit 42a and the second register mark detection unit 42b, respectively. The graph 61 of FIG. 3 (a) shows the signal waveform of the first register mark 6A detected by the first register mark detector 42a, and the graph 62 of FIG. 3 (b) is detected by the first register mark detector 42a. The signal waveform of the 2nd register mark 6B is shown.

  Here, as described above, the first photoelectric sensor unit 31a and the second photoelectric sensor unit 31b are disposed at an interval L, and the first register mark 6A and the second register mark 6B also have an interval L when no register deviation occurs. Printed with Therefore, when no misregistration occurs, the first register mark 6A and the second register mark 6B are detected at substantially the same timing. From this, the time t1 when the first register mark 6A is detected by the first register mark detecting unit 42a (that is, the signal strength of the combined signal and the predetermined detection threshold is exceeded), and the second register mark detecting unit 42b When the time t2 at which the register mark 6B is detected is substantially the same, the registration unit 43 determines that no register error has occurred. On the other hand, when the time t1 and the time t2 are different, the registration unit 43 determines that the misregistration has occurred as much as the difference between the time t1 and the time t2 multiplied by the feeding speed of the web 2.

  If a registration error occurs, the registration unit 43 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 misalignment in the traveling direction of the web 2, and the sidelay adjusts misalignment in the width direction of the web 2.

  The concentration control unit 50 includes a correspondence relationship holding unit 51, a color determination unit 52, a color acquisition unit 53, a determination unit 54, and a setting unit 55. The color determination unit 52 receives a captured image from the first imaging unit 37a and the second imaging unit 37b. The color determination unit 52 determines the color of the web 2 serving as the base and the colors of the first register mark 6A and the second register mark 6B from each of the received captured images. The color acquisition unit 53 is previously input by the user via the color of the web 2 obtained as a result of the determination by the color determination unit 52, the color of the first justification mark 6A, the color of the second justification mark 6B, or the input device (not shown). The color of the web 2 and the color of the first register mark 6A and the second register mark 6B are acquired.

  FIG. 4 shows the data structure of the correspondence relationship holding unit 51. As shown in FIG. The correspondence relationship holding unit 51 associates and holds the base color 51a, the registration mark color 51b, and the photoelectric conversion area 51c. The base color 51a indicates the color of the web 2 which is the base. The register mark color 51 b indicates the color of the register mark 6. The photoelectric conversion area 51c outputs a signal having the highest S / N ratio when the color of the web 2 is the base color 51a and the color of the register mark 6 is the register mark color 51b (that is, the signal strength by the web 2) And the photoelectric conversion area where the difference between the signal strength of the register mark 6 and the signal strength by the In other words, the photoelectric conversion area 51 c indicates a photoelectric conversion area that outputs a signal to be amplified by the adjustment unit 41. For example, when web 2 is "yellow" and register mark 6 is "orange" or when web 2 is "orange" and register mark 6 is "yellow", that is, the combination of the color of web 2 and the color of register mark 6 is In the case of "yellow" and "orange", the "second photoelectric conversion area" is a photoelectric conversion area that outputs a signal with the highest S / N ratio, and is a photoelectric conversion area that outputs a signal to be amplified. It shows.

  The determination unit 54 determines which signal from the photoelectric conversion region is to be amplified by the adjustment unit 41. Specifically, the determination unit 54 extracts, from the correspondence relationship holding unit 51, the photoelectric conversion region corresponding to the combination of the color of the web 2 and the color of the first register mark 6A acquired by the color acquisition unit 53. Similarly, the determination unit 54 extracts, from the correspondence relationship holding unit 51, a photoelectric conversion region corresponding to the combination of the color of the web 2 and the color of the second register mark 6B acquired by the color acquisition unit 53. For example, when the combination of the color of the web 2 and the color of the register mark 6 acquired by the color acquisition unit 53 is “yellow” and “orange”, the determination unit 54 adjusts the signal from the “second photoelectric conversion region” It is decided to amplify at 41.

  The setting unit 55 instructs each of the first adjustment unit 41a and the second adjustment unit 41b to amplify the signal from the photoelectric conversion region determined (extracted) by the determination unit 54.

The operation of the pre-adjustment processing of the multicolor printing system configured as described above will be described.
The light source 32 emits light to the area through which the register mark passes, and the light detection element 34 receives the reflected light from the web 2. Each photoelectric conversion area of the light detection element 34 outputs a signal corresponding to the received light. Further, each imaging unit of the sensor 30 images the web 2 and the register mark. The color determination unit 52 of the concentration control unit 50 determines the color of the web 2 and the color of the register mark from the captured image acquired by the imaging unit. The color acquisition unit 53 acquires the color of the web 2 obtained as a result of the determination and the colors of the first register mark 6A and the second register mark 6B. Alternatively, the color acquiring unit 53 acquires the color of the web 2 and the colors of the first register mark 6A and the second register mark 6B, which are input in advance by the user.

  The determination unit 54 refers to the correspondence relationship holding unit 51, and a signal to be amplified by the first adjustment unit 41a with respect to the combination of the color of the web 2 acquired by the color acquisition unit 53 and the color of the first register mark 6A. The photoelectric conversion area which outputs The setting unit 55 instructs the first adjustment unit 41 a to amplify the determined photoelectric conversion region. Similarly, with reference to the correspondence holding unit 51, the determining unit 54 amplifies the set of the color of the web 2 and the color of the second register mark 6B acquired by the color acquiring unit 53 by the first adjustment unit 41a. The photoelectric conversion area which outputs the signal which should be made to be determined. The setting unit 55 instructs the second adjustment unit 41 b to amplify the determined photoelectric conversion region.

  The first adjustment unit 41 a of the machine-side control unit 40 adjusts the signal according to the instruction of the setting unit 55. The first register mark detection unit 42a detects a register mark based on the signal adjusted by the first adjustment unit 41a. Similarly, the second adjustment unit 41b adjusts the signal according to the instruction of the setting unit 55, and the second register mark detection unit 42b detects the register mark based on the signal adjusted by the second adjustment unit 41b. The registration unit 43 determines the presence or absence of a registration deviation based on the detection results of each register mark detection unit 42, and increases or decreases the amount of rotation of the plate cylinder 11 of the second printing unit 10B when a registration deviation occurs. , Eliminate the gap.

  According to the multicolor printing system 100 according to the present embodiment, the intensity ratio of the signal from each photoelectric conversion area is adjusted based on the color of the web 2 and the color of the register mark. In particular, based on the color of the web 2 and the color of the register mark, the intensity ratio of the signal from each photoelectric conversion region is adjusted so that the signal having a high S / N ratio is amplified. As a result, it is possible to improve the detection accuracy of the register mark.

  The multi-color printing system according to the embodiment has been described above. It will be understood by those skilled in the art that this embodiment is an exemplification, and that various modifications can be made to the combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there. The following is a modification.

(Modification 1)
Although the multi-color printing system 100 is described in the embodiment as including the two printing units, the first printing unit 10A and the second printing unit 10B, 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 2)
Although not particularly mentioned in the embodiment, the adjustment unit 41 amplifies the signal from the photoelectric conversion region so that the signal intensity of the combined signal output to the registration mark detection unit 42 becomes equal to or higher than the detection threshold. Good. In this case, the register mark can be detected with higher accuracy.

(Modification 3)
FIGS. 5A and 5B are graphs showing other examples of detection results by the first register mark detection unit 42a and the second register mark detection unit 42b, respectively. The graph 71 of FIG. 5 (a) shows the signal waveform of the register mark detected by the first register mark detector 42a, and the graph 72 of FIG. 5 (b) shows the register mark detected by the first register mark detector 42a. Shows a signal waveform of Even when the register waveform does not actually occur and the signal waveform starts to rise as shown in FIG. 5 at the same time at time t0, the difference in the height of the waveform, that is, the maximum value of the signal strength makes the first register It can be detected that the time t1 when the first register mark 6A is detected by the mark detection unit 42a and the time t2 when the second register mark 6B is detected by the second register mark detection unit 42b are different. Therefore, the first adjustment unit 41a and the second adjustment unit 41b are the maximum value of the signal strength of the combined signal output to the first register mark detection unit 42a and the combined signal output to the second register mark detection unit 42b. Signal from the photoelectric conversion area of the first photoelectric sensor unit 31a and the signal from the photoelectric conversion area of the second photoelectric sensor unit 31b are amplified so that the difference between the signal strength and the maximum value of the May be According to this modification, it is possible to determine the presence or absence of misregistration with higher accuracy.

(Modification 4)
Although the embodiment has been described for the case where the light receiving element 36 is an RGB photodiode having three photoelectric conversion regions, the present invention is not limited to this. The light receiving element 36 may be an RGB photodiode having two or four or more photoelectric conversion regions. Further, the light receiving element 36 may be other than the RGB photodiode. In these cases, the degree of freedom in design increases.

(Modification 5)
In the embodiment, the first photoelectric sensor unit 31a and the second photoelectric sensor unit 31b are described as receiving light reflected from the web 2. However, the present invention is not limited to this. For example, the first photoelectric sensor unit 31a and the second photoelectric sensor unit 31b may be used. The photoelectric sensor unit 31 b may be configured to receive the transmitted light from the web 2.

(Modification 6)
Although the embodiment has described the case where the machine-side control unit 40 includes the adjustment unit 41, the present invention is not limited to this. The sensor 30 may have the function of the adjustment unit 41.

  Any combination of the above-described embodiment and the modification is also useful as an embodiment of the present invention. The new embodiments resulting from the combination combine the effects of each of the combined embodiments and variations.

  20 registration control unit, 30 sensor, 30A first sensor, 30B second sensor, 31a first photoelectric sensor unit, 31b second photoelectric sensor unit, 36 light receiving elements, 37a first imaging unit, 37b second imaging unit, 40 machines Side control unit, 41 adjustment unit, 42 register mark detection unit, 43 registration unit, 50 central control unit, 51 correspondence relationship holding unit, 52 color determination unit, 53 color acquisition unit, 54 determination unit, 55 setting unit, 100 multi-color printing system.

Claims (8)

The light from the printing medium on which the registration mark is printed is received by the light receiving element having a plurality of photoelectric conversion regions having different spectral sensitivity characteristics, and the light from the printing medium is received as the signal output from the light receiving element A registration control unit for detecting the registration mark printed on the print medium based on the information;
An acquisition unit that acquires the color of the register mark base color and the printed on the print medium of the print medium,
An adjusting unit configured to adjust an intensity ratio of a signal from each photoelectric conversion region based on the color of the background and the color of the register mark acquired by the acquiring unit;
Equipped with
The adjustment unit amplifies only the signal intensity from the photoelectric conversion region in which the difference between the signal intensity of the background and the signal intensity of the registration mark is maximum with respect to the color of the foundation and the color of the registration mark acquired by the acquisition unit. A register control unit characterized by adjusting. The light from the printing medium on which the registration mark is printed is received by the light receiving element having a plurality of photoelectric conversion regions having different spectral sensitivity characteristics, and the light from the printing medium is received as the signal output from the light receiving element A registration control unit for detecting the registration mark printed on the print medium based on the information;
A correspondence relationship holding unit which associates and holds a combination of base color and register mark color, and a photoelectric conversion region where the difference between the signal strength of the base and the signal strength of the register mark is maximum with respect to the combination;
An acquisition unit that acquires the color of the register mark base color and the printed on the print medium of the print medium,
A determination unit which extracts, from the correspondence relationship holding unit, a photoelectric conversion area corresponding to a combination of the color of the background and the color of the register mark acquired by the acquisition unit;
An adjusting unit that adjusts the intensity ratio of the signal from each photoelectric conversion region by amplifying the signal intensity from the photoelectric conversion region extracted by the determining unit;
A register control unit comprising:   The adjustment unit adjusts the intensity ratio of signals from each photoelectric conversion region such that the signal intensity of a combined signal obtained by combining the signals from each photoelectric conversion region is equal to or higher than a predetermined threshold. Register control unit according to 2. The printing medium is further printed with a registration mark different from the registration mark.
The registration control unit receives light from the print medium by another light receiving element having a plurality of photoelectric conversion regions having different spectral sensitivity characteristics and spaced apart from the light receiving element by a predetermined distance, The other registration mark printed on the print medium is also detected based on the signal output from the light receiving element of
The acquisition unit acquires a base color of the print medium, a color of the register mark printed on the print medium, and a color of the other register mark.
The adjustment unit is a signal intensity peak of a combined signal obtained by combining the signals from the respective photoelectric conversion regions of the light receiving element and a signal intensity of the combined signal obtained by combining the signals from the respective photoelectric conversion regions of the other light receiving element. The intensity ratio of the signal from each photoelectric conversion area of the light receiving element and the intensity ratio of the signal from each photoelectric conversion area of the other light receiving element are each set so that the difference with the peak is equal to or less than a predetermined value. The register control unit according to any one of claims 1 to 3, characterized by adjusting. The light from the printing medium on which the registration mark is printed is received by the light receiving element having a plurality of photoelectric conversion regions having different spectral sensitivity characteristics, and the light from the printing medium is received as the signal output from the light receiving element A registration control unit for detecting the registration mark printed on the print medium based on the information;
An imaging unit configured to image the register mark printed on the print medium and the ground of the print medium ;
A color determination unit that determines the color of the register mark and the color of the background from the image acquired by the imaging unit;
An acquisition unit that acquires the color of the register mark and the color of the background obtained as a result of the determination by the color determination unit;
An adjusting unit configured to adjust an intensity ratio of a signal from each photoelectric conversion region based on the color of the background and the color of the register mark acquired by the acquiring unit;
A register control unit comprising:   A multi-color printing system comprising the register control unit according to any one of claims 1 to 5. The light from the printing medium on which the registration mark is printed is received by the light receiving element having a plurality of photoelectric conversion regions having different spectral sensitivity characteristics, and the light from the printing medium is received as the signal output from the light receiving element A registration mark detection method for detecting the registration mark printed on the print medium based on the information.
Acquiring the color of the background color and the printing medium of the register mark the printed on the print medium,
Adjusting the intensity ratio of the signal from each of the plurality of photoelectric conversion regions based on the color of the register mark and the color of the background obtained,
In the adjusting step, only the signal intensity from the photoelectric conversion region in which the difference between the signal intensity of the background and the signal intensity of the registration mark is maximum is amplified with respect to the acquired color of the background and the color of the registration mark. A method of detecting a register mark characterized by: The light from the printing medium on which the registration mark is printed is received by the light receiving element having a plurality of photoelectric conversion regions having different spectral sensitivity characteristics, and the light from the printing medium is received as the signal output from the light receiving element A registration mark detection method for detecting the registration mark printed on the print medium based on the information.
Acquiring the color of the background color and the printing medium of the register mark the printed on the print medium,
From the correspondence relationship holding unit which associates and holds the combination of the background color and the color of the register mark and the photoelectric conversion region where the difference between the signal strength of the substrate and the signal strength of the register mark is maximum for the combination Extracting a photoelectric conversion region corresponding to the combination of the color of the background and the color of the register mark acquired in the acquiring step;
Adjusting the intensity ratio of the signal from each photoelectric conversion region by amplifying the signal intensity from the photoelectric conversion region extracted in the extracting step, and detecting the register mark.

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