JP2950175B2 - Register mark detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting register marks printed for controlling color misregistration of a web to be printed in multiple colors.

[0002]

2. Description of the Related Art In the case of performing overprinting on a web such as paper or film using a plurality of plate cylinders, a color shift occurs unless each color is printed in a predetermined position. Since this color misregistration is caused by rotation misregistration of the plate cylinder, web elongation, and the like, each plate cylinder is caused to print a pattern in each color and a register mark is printed at a predetermined position, and the register mark is detected. , Register control for preventing color misregistration is performed.

As an example of register mark detection, an example of printing on paper by a gravure rotary printing press shown in FIG. 4 will be described.
The order of printing by the plate cylinder is arbitrary, and the number of colors is also arbitrary. In offset printing, when printing on normal paper, the first color is yellow, the second color is red, the third color is blue, and the fourth color is black. Here, as an example of gravure rotary printing, an example in which these four colors are reversed is illustrated. The web 10 to be printed is unwound from the unwinding reel 1, pressed against the plate cylinder 2 by the impression cylinder 3, and printed by the plate cylinder 2. As many combinations of the plate cylinder 2 and the impression cylinder 3 as the number of colors to be printed on the web 10 are provided. The compensator roll 5 moves in the direction of the arrow to prevent color misregistration. The guide roll 4 guides the web 10 to the compensator roll 5. The encoder 6 rotates in response to the rotation of the plate cylinder 2, detects the speed of the web 10 and the rotational position of the plate cylinder 2, and transmits them to the control unit 9. Each plate cylinder 2a, 2
Since encoders b, 2c, and 2d are configured to rotate mechanically synchronously, the encoder 6 is installed on one plate cylinder 2b. The register mark detector 7 is provided on the exit side of the second and subsequent plate cylinders 2, detects register marks, and transmits the register marks to the control unit 9. The correction unit 8 moves the compensator roll 5 in the direction indicated by the arrow in accordance with an instruction from the control unit 9 to prevent the register mark from shifting. The control unit 9 outputs control data to the correction unit 8 based on data from the encoder 6 and the register mark detector 7.

FIG. 5 shows a register mark printed by each plate cylinder 2 in a blank portion without a pattern at the end of the web 10. The register marks are printed at equal intervals, for example, at intervals of 20 mm. The register mark detector 7a sets the black and blue register marks among the detected four color register marks as measurement targets for control. The blue and red register mark detector 7c sets the red and yellow register marks as measurement targets for control, respectively. Each detector 7a, 7
Each of b and 7c has a main and a sub light receiving element, and uses only a signal of a predetermined register mark from signals detected by each light receiving element. For example, in the detector 7a, the main light receiving element extracts the black register mark from the detection signals of the respective colors, and the secondary light receiving element extracts the blue register mark, and controls the position of the blue register mark with reference to the black register mark.

Thus, each register mark detector 7
The detected values of the register mark in charge are sent to the control unit 9 from a to 7c, but the detected values greatly differ depending on the colors of the register marks. FIG. 6 shows an example of the detected value of the register mark. FIG. 6A shows the detected value of each color, and FIG. 6B shows the amplified value of the detected value.

In order to set a gate for detecting only a target color register mark at the start of operation, it is necessary to visually recognize the signal positions of all register marks, and as shown in FIG. Observe the register marks other than the two colors. As the register mark, a part of the pattern may be used as the register mark, or a pattern other than the register mark or another mark may be provided outside the gate as in the signal of FIG. Generally, the detection value of the black register mark is the largest,
Red and blue are second, and yellow is the smallest. The order and the number of colors of the register marks in FIGS. 5 and 6 are various depending on the printing target. In FIG. 6, L is a repeat length with the plate cylinder circumference as one unit, and the same pattern is repeatedly printed for each repeat length.

[0007]

A small detection signal is amplified to a predetermined value and then used as a control signal.
Conventionally, each detection value was amplified at the same amplification factor as this amplification method. In this way, if the maximum peak value is large in the detection signal, the amplification factor applied to the entire signal is determined by the maximum peak value, so the minimum peak value may not reach the required control value, and control is not possible. Or unstable control. Explaining in the example of FIG. 6, when the detected value of the black register mark is h2 and the detected value of the yellow register mark is h1, the amplification factor is set to h2 at the maximum by satisfying conditions such as a predetermined distortion factor. It is determined by things. For this reason, the yellow register mark is amplified only to H1, and there is a problem that H1 is insufficient as a control signal.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to make the detected value of a register mark assigned to each register mark detector a constant value. Also,
It is an object of the present invention to set the detected value of the register mark in charge to approximately 1, and to set the maximum detected value of the remaining register marks to approximately 1 while maintaining the relative magnitude relationship.

[0009]

To achieve the above object, according to the first aspect of the present invention, there is provided a register mark detecting means for detecting a register mark printed by a plate cylinder, and a rotational position for detecting a rotational position of the plate cylinder. Based on the detection means and a rotational position of the plate cylinder when the predetermined register mark is detected, a gate indicating a period during which the register mark detection means detects the predetermined register mark is set based on the output of the rotation position detection means. Gate setting means, peak value storage means for storing a peak value of a predetermined register mark detection value in the gate, and register mark detection value in the gate divided by a peak value stored in the peak value storage means Calculating means for outputting a value as a detection value of a predetermined register mark.

[0010] In the invention according to claim 2, the peak value storage means includes a register of a picture surface printed immediately before the picture surface on which the register mark currently detected by the register mark detection means is printed. The detected value of the mark is stored.

According to the present invention, the register mark detecting means for detecting the register mark printed by the plate cylinder, the rotational position detecting means for detecting the rotational position of the plate cylinder, and the predetermined register mark are detected. A gate setting means for setting a gate indicating a period during which the register mark detecting means detects a predetermined register mark based on an output of the rotational position detecting means from a rotational position of the plate cylinder at the time; First peak value storage means for storing the peak value of the register mark detection value, second peak value storage means for storing the maximum peak values of all the marks printed in one picture plane, and the register mark detection means Outputs a first detection value obtained by dividing a detection value by a value stored in the first peak value storage means when a predetermined register mark is detected, Upon detecting a mark other than the mark are those comprising a calculating means for outputting a second detection value obtained by dividing the detected value with the stored value of the second peak value storing means.

Further, in the invention according to claim 4, the first peak value storage means and the second peak value storage means are each one of the first and second peak value storage means from the picture surface on which the register mark currently detected by the register mark detection means is printed. The detected value of the register mark of the picture surface printed immediately before is stored.

[0013]

According to the first aspect of the present invention, the register mark detecting means detects the register mark in the set gate.
The gate detects only the register mark of the target color to be controlled, and indicates the timing at which the register mark in charge of detection by the register mark detection means passes through the detection position, and is set by the gate setting means. .
Since the register mark repeatedly appears on the web printed by the plate cylinder for each circumferential length of the plate cylinder, the register mark to be detected is output from the rotational position detecting means when the register mark detecting means detects the register mark. The gate position is set by checking the rotational position, and then providing a certain width substantially at the center when the rotational position detecting means reaches the rotational position. The register mark detecting means detects the register mark in the gate, and the peak value storing means stores the peak value of the detected value. The calculation means detects the value currently detected by the register mark detection means and outputs a value obtained by dividing the value by the previously stored peak value. When the plate cylinder starts printing and is in a stable state, the peak value stored in the peak value storage means is almost equal to the currently detected peak value. The peak value of the value divided by the value is almost 1. As a result, the detected value of the register mark to be detected is a stable value because the peak value is almost 1 regardless of whether the value is small or large. If the value of 1 is not appropriate as a control signal, the control signal can be set to an appropriate value by an amplifier. In this case, the amplification factor is not limited by the maximum detection value described as a problem of the conventional example.

According to a second aspect of the present invention, in the first aspect, the peak value storage means includes a register printed on a picture surface one print pattern face before the register mark on the printing face currently detected by the register mark detection means. The peak value of the mark detection value is stored. Since the detected value of the register mark on the adjacent picture surface hardly changes, the peak output value of the calculating means approaches 1.

According to the third aspect of the present invention, similarly to the first aspect of the present invention, the register mark in the gate is detected, and its output is output as approximately 1 by the arithmetic means, and all the marks within one repeat length are detected. Then, the maximum value of the peak value is stored in the second peak value storage means, and a value obtained by dividing the detected value of the mark outside the gate by the storage value of the second peak value storage means is also output. As a result, the detected values of the other register marks become output values such that the maximum detected value of the mark or picture within one repeat length becomes substantially 1 while maintaining the relative size relationship. If this detection value can be visually displayed, the gate setting at the beginning of printing becomes easy.

According to a fourth aspect of the present invention, the peak values stored by the first peak value storage means and the second peak value storage means of the third aspect are stored in a pattern surface one pattern surface before the currently detected pattern surface. This is the detection value of the printed register mark. As a result, the peak value of the calculated value of the register mark in the gate and the peak value of the calculated value of the detected value that is the maximum peak value outside the gate become substantially 1 as in the second aspect of the invention.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment. 4 have the same meanings. The pattern and the register mark of the plate cylinder 2 are printed on the web 10 by the plate cylinder 2 and the impression cylinder 3. An encoder 6 is connected to one of the plate cylinders 2 directly or via a gear or the like on the rotation shaft of the plate cylinder 2. The encoder 6 has a Z-phase that outputs one pulse per rotation, an A-phase and a B-phase that generates N pulses per rotation, and the A-phase or the B-phase based on when one Z-phase pulse is output. Addressing all N pulses and associating the reference position of the plate cylinder 2 with one of the A-phase or B-phase addresses, counting the number of pulses of the encoder 6 allows
The rotational position of the plate cylinder 2 can be detected. Note that the A phase and the B phase are 90 degrees out of phase, and the rotation direction can be detected using this. The register mark detector 7 has two light receiving elements, and detects two register marks printed side by side as control targets. That is, each light receiving element detects a predetermined register mark by each gate. Since the encoder outputs a position in the same pattern repeatedly printed by the plate cylinder 2 as a signal, the encoder may be attached to a feed roller as shown at 6 'in FIG. It may be attached to a processing machine such as.

The gate generator 11 sets a gate to each of the light receiving elements of the register mark detectors 7a, 7b, 7c when a predetermined register mark comes to be detected by the light receiving element. In this case, at the time of trial printing, the address of a pulse generated by the encoder 6 when a predetermined register mark is detected by a predetermined light receiving element may be searched, and a gate may be set before and after the address. The first peak hold circuit 12 holds the peak value of the detected value of the register mark for which the gate has been set, for a period slightly longer than the gate period. The first sample hold circuit 13 holds the hold value of the first peak hold circuit 12 until the first peak hold circuit 12 holds the peak value.
The second peak hold circuit 14 holds the maximum peak value of the detected value of the mark or picture within one repeat length. Second
The sample hold circuit 15 is the second peak hold circuit 1
The maximum peak value before one pattern surface (hereinafter, referred to as one repeat length) of No. 4 is held until the next pattern gate closes. The timing pulse generator 16 generates an operation timing signal for each of the first peak hold circuit 12, the first sample hold circuit 13, the second peak hold circuit 14, and the second sample hold circuit 15 based on the gate signal. The analog switch 17 allows the output of the first sample and hold circuit 13 to pass during the gate period, and allows the output of the second sample and hold circuit 15 to pass during other periods.

The arithmetic unit 18 detects the detected value of the register mark in the gate when the gate is set, and the register mark in which the gate is set for one repeat length when the gate is not set (hereinafter referred to as a predetermined register mark). Using the detected value of the mark or picture other than the numerator as the numerator, the output of the analog switch 17, that is, the division using the maximum signal within one repeat length as the denominator is performed.

FIG. 2 is a configuration circuit diagram of the register mark detector 7. As the light receiving element 20, a silicon photodiode or the like is used. The light receiving element 20 receives reflected light from the register mark with respect to illumination light provided in the register mark detector 7, and converts the reflected light into a current corresponding to the luminance. The current / voltage converter 21 converts the current from the light receiving element 21 into a voltage. Amplifier 22
Amplifies the output of the current / voltage converter 21. Filter 2
Numeral 3 extracts a change value of the output of the amplifier 22. When the color of the register mark is silver and the illumination light is ultraviolet, the inverting / non-inverting device 24 may invert the output of the light receiving element in the same direction as the other register marks. Sometimes used. The amplifier 25 amplifies the output of the inverting / non-inverting device 24.

FIG. 3 is a timing chart of FIG. AK
2 is a diagram showing signals at positions A to K shown in FIG. A indicates a register mark detection value for each repeat length L that is received and amplified by one light receiving element 20 of the register mark detector 7. The detection value at which the detection sensitivity is minimum is a, and the detection value at which the detection sensitivity is maximum is b. B indicates that a gate has been set for the detection value a by the gate generator 11. C indicates a period during which the peak value of the detection value a is held in the first peak hold circuit 12, and is slightly longer than the gate period of B. D is a signal that falls when the gate signal of B rises, and represents the timing at which the outputs of the first peak hold circuit 12 and the second peak hold circuit 14 are sampled. E is a timing signal for resetting the second peak hold circuit 14.

F indicates the hold value of the first peak hold circuit 12, and holds the peak value during the period of the signal C.
G indicates a hold value of the first sample and hold circuit 13. The detection value of the first peak hold circuit 12, which samples and holds the value of F at the falling edge of D, is held until the next first peak hold value is sampled and held. H
Indicates a hold value of the second peak hold circuit 14, and E
The hold value is reset at the falling edge of, and the next peak value is held. I is a sample value of the hold value of the second peak hold circuit 14 in which H is held at the falling edge of D, and holds the hold value one repeat length before H. J is analog switch 1
7 represents the output, the gate period of B represents the value of G, and the other periods represent the value of I.

K represents the output of the arithmetic unit 18. That is, it is a value obtained by dividing the detected value of A by the value of J. The value of the detection value a is a value obtained by dividing by the peak value detected one repeat length before. For this reason, if the detected value is substantially the same for each repeat length, the divided value will be substantially 1. As a result, even if the small detection value a changes, the detection value a becomes almost always 1 and becomes stable control data. Signals other than the detected value a within one repeat length are values obtained by dividing by the maximum value of the peak value at the repeat length immediately before the repeat length. As a result, the value of the maximum detection value b within one repeat length becomes almost 1, and the detection values b other than the detection value a and the detection value b are set to 1 while maintaining the magnitude relationship with the detection value b. At this time, the value changes accordingly. As a result, the detection values a, 1
The maximum peak value b within the repeat length is almost 1. In addition, other than the detection values a and b, the relative relationship of the magnitude with the detection value b can be understood. By looking at the signal K in FIG. 3, the magnitude of the signal inside the gate is 1, so that it can be fully recognized. In addition, the relative magnitude relationship between the signals outside the gate and the relative magnitude of the signal outside the gate are large. Since the relationship between the various positions can be recognized, the gate can be easily set at the start of the operation. In addition,
The detection values other than the detection value a indicated by K in FIG. 3 are not necessary for control, but are provided so that the operator can refer to the detection state of the entire register mark within one repeat length as a reference. .

The circuits from the gate generator 11 to the arithmetic unit 18 shown in FIG. 1 are provided for each light receiving element. In the example of FIG. 4, there are three register mark detectors 7a to 7c, and each detector is provided with two light receiving elements. Therefore, six systems of circuits are provided, and the detection signal is stabilized. . The register marks detected in this way are all set as gates and all are output as substantially one value. In this embodiment, the case of four-color printing has been described. However, in the case of five-color and six-color printing, circuits of eight and ten systems are provided, and the same stabilization processing is performed.

In the present invention, the denominator in the arithmetic unit 18 is set to the value of the repeat length immediately before the currently detected repeat length, but the value is not limited to one before and may be before. Although the register mark is detected, a part of the picture may be used instead of the register mark. In this embodiment, a circuit is used in which the maximum value of the signal outside the gate is set to 1 so that the gate at the start of operation can be easily set, but only the signal inside the gate can be detected stably during automatic operation. It is not necessary to set the maximum value of the signal outside the gate to 1 and switch the signal inside and outside the gate. In the present embodiment, an example of gravure rotary printing has been described, but it may be used for mark detection in offset printing.

[0026]

As is apparent from the above description, according to the present invention, the detection value can be made substantially 1 by dividing the detection value of the register mark detected in the gate by the detection value detected before the detection. . This enables stable register control. Also, the maximum value of the detected value of the mark within one repeat length is stored, and the maximum value of the detected value is set to approximately 1 by dividing each detected value by the stored value. Since it is possible to know the state of the magnitude of the detection value holding the magnitude relation, it is possible to easily set the gate at the start of operation.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an embodiment.

FIG. 2 is a block diagram illustrating a configuration of a register mark detector.

FIG. 3 is a time chart showing the operation of the embodiment.

FIG. 4 is a diagram illustrating register control of a rotary printing press.

FIG. 5 is a diagram illustrating an example of a register mark.

FIG. 6 is a diagram illustrating a conventional register mark detection value amplification process.

[Explanation of symbols]

 2 plate cylinder 3 impression cylinder 6 encoder 7 register mark detector 9 control unit 10 web 11 gate generator 12 first peak hold circuit 13 first sample hold circuit 14 second peak hold circuit 15 second sample hold circuit 16 timing pulse generation Unit 17 Analog switch 18 Operation unit

Claims (4)

(57) [Claims] 1. A register mark detecting means for detecting a register mark printed by a plate cylinder, a rotational position detecting means for detecting a rotational position of the plate cylinder, and a rotational position of the plate cylinder when a predetermined register mark is detected. A gate setting means for setting a gate representing a period during which the register mark detecting means detects a predetermined register mark based on the output of the rotational position detecting means; and a peak value of a predetermined register mark detected value in the gate. And a calculating means for outputting a value obtained by dividing the register mark detection value in the gate by the peak value stored in the peak value storage means as a predetermined register mark detection value. A register mark detection device characterized by the above-mentioned. 2. The peak value storage means stores a detected value of a register mark on a picture surface printed immediately before a picture surface on which a register mark currently detected by the register mark detection means is printed. 2. The register mark detection device according to claim 1, wherein: 3. A register mark detecting means for detecting a register mark printed by a plate cylinder, a rotational position detecting means for detecting a rotational position of the plate cylinder, and a rotational position of the plate cylinder when a predetermined register mark is detected. A gate setting means for setting a gate representing a period during which the register mark detecting means detects a predetermined register mark based on the output of the rotational position detecting means; and a peak value of a predetermined register mark detected value in the gate. A first peak value storage means for storing the maximum peak value of all the marks printed in one picture surface, and a register mark detection means for storing a predetermined register mark. When a detection is made, a first detection value obtained by dividing the detection value by the storage value of the first peak value storage means is output, and a mark other than a predetermined register mark is detected. And a calculating means for outputting a second detected value obtained by dividing the detected value by a value stored in the second peak value storing means. 4. The image processing apparatus according to claim 1, wherein the first peak value storage means and the second peak value storage means store the register mark detected by the register mark detection means at least one time from a picture surface on which the register mark is printed.
4. The register mark detecting device according to claim 3, wherein a detected value of a register mark of a picture surface printed immediately before is stored.