JPH0579123B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a web position measuring device used in a web guide position for controlling the position in the width direction of a running web (rolled paper) in a rotary printing press.

[Conventional technology]

Normally, in a rotary printing press, a web guide device is installed in the web travel path between the paper feed section and the printing section, which controls the widthwise position of the web at a constant level so that the pattern is always printed at a constant position on the web. It is provided.
In addition, a web guide device is installed just before the folding machine so that when the web is fed to the folding machine after printing in the printing section, the relative positional relationship between the folds or slits and the pattern is constant. It is provided. Causes of misalignment in the width direction of the web include tension fluctuations, paper quality variations, printing speed changes, and winding changes.

The web guide device prints between the edge position of the side edge of the web and the reference position of the web, that is, the position where the pattern is printed at a certain position on the web, or the relative positional relationship between the folds or slits and the pattern is constant. According to feedback control or other automatic control methods, the winding shaft of the paper feed section is moved in the axial direction, or the guide rollers in the web travel path are oscillated so that the web is aligned with the correct position.

Conventional web guide devices had somewhat loose or ambiguous constraints on the printing position of the design on the web, or the relative position of the folds or slits and the design, so it was necessary to control the position in the width direction of the web. However, it would have been sufficient to satisfy the capability of within ±1 mm in terms of swing width. However, depending on the printing item, the constraints may be more severe, and as rotary printing presses become more automated and labor-saving, more precise position control in the width direction of the web is required. Accordingly, a device for measuring the edge position of the side end of the web of the web guide device is also required to have a higher measurement capability.

Conventional web guide devices use web position measuring devices using air pressure detection as shown in FIG. 4, and web position measuring devices using photoelectric conversion elements as shown in FIGS. 5 and 6.

In the web position measuring device shown in Fig. 4, pump 1b
Air sent out from the nozzle 1a passes through the nozzle 1a, and the side end of the web w is positioned in the air passage. The air passage is blocked depending on the position of the web w in the width direction, and the air pressure after passing through the nozzle 1a changes.
By measuring this with the detector 1c, the position of the web w in the width direction is measured.

In the web position measuring device shown in FIG. 5, a light source 2b and a light receiving element 2b are disposed facing each other in a sensor head 2a, and the side edge of the web w is positioned between them.
The amount of light emitted from the light source 2b and incident on the light receiving element 2c changes depending on the position in the width direction of the web w, and by detecting the current from the light receiving element 2c with the current detector 2d, the position in the width direction of the web w can be determined. be measured.

In the web position measuring device shown in FIG. 6, a light source 3b and a line sensor 3b are disposed facing each other in a sensor head 3a, and the side edge of the web w is positioned between them. The number of light receiving elements of the line sensor 3c that are irradiated with light or shielded from light changes depending on the position in the width direction of the web w. The position of the web w in the width direction is measured by counting voltage pulses proportional to the amount of light received by each element output in time series from the line sensor 3c using a counter 3d.

[Problem that the invention seeks to solve]

The measurement accuracy of these web position measuring devices using photoelectric conversion elements is higher than those that detect changes in air pressure, but those using photodetectors as shown in Figure 5 still have an accuracy of about 0.05 mm. (max). Moreover, this device has a drawback that, although the measurement accuracy is good when the side edge of the web w is located near the center of the light-receiving surface of the light-receiving element 2c, the measurement accuracy deteriorates as the distance from the center increases.

In addition, when using a line sensor as shown in Fig. 6, measurement accuracy can be improved by using an optical system with lenses to define the field of view, but the use of lenses increases the size of the sensor head 3a itself and makes the structure complicated. Moreover, the installation space for the sensor head 3a may also become large, which is inconvenient.
Close-contact line sensors have also been developed in which the line sensor itself is large and does not require a complicated optical system.
The highest element density is around 16 elements/mm, and the measurement accuracy is only 0.06 mm.

In order to control the position of the web in the width direction more accurately than conventional web guide devices,
The measurement accuracy of conventional web position measuring devices is insufficient, and there is a need to further improve the accuracy of the web position measuring devices.

This invention was made in order to cope with the above-mentioned situation, and by performing simple signal processing while using a line sensor with limited measurement accuracy, it is possible to measure the side edges of the web with higher accuracy with a simple equipment configuration. The object is to provide a web position measuring device capable of performing position measurements.

[Means for solving problems]

The web position measuring device according to the present invention is provided at a side end of a web running path so that the arrangement direction of the light receiving elements intersects with the running direction of the web, and line sensor means generates a video signal for each light receiving element; edge detection means that compares the video signal and the reference signal and generates an edge signal according to the position of the light receiving element in which the magnitude relationship of both signals is reversed; , a first measuring means for roughly measuring the edge position in units of pitch of the light receiving element; and second measuring means for precisely measuring the edge position on a unit-by-unit basis.

[Effect]

According to the web position measuring device according to the present invention,
The edge position of the web side edge can be measured with an accuracy less than the pitch of the light receiving element of the line sensor. Moreover, a rough measured value in pitch units is obtained according to the product of the position of the light receiving element and the pitch of the light receiving element where the magnitude relationship between the output of the light receiving element and the reference signal is reversed, and a precise measured value in pitch units or less is obtained by computer processing. As a result, measurements can be performed with a simple circuit configuration and a simple computer program.

〔Example〕

An embodiment of the web position measuring device according to the present invention will be described below with reference to the drawings.

First, the measurement principle will be explained with reference to FIG.
In this invention, a line sensor in which a large number of minute light-receiving elements are arranged in a straight line is used to image the vicinity of the side edge of the web w, and from the image signal, a rough measurement value L1 of each pixel and a precise measurement within one pixel are obtained. Find the value L2 and
Let the sum L1+L2 be the edge position of the web side end.

In Figure 2, light from a light source (not shown) is incident on the light-receiving elements of the line sensor from the first element C1 to the n-th element Cn, and from the n-th element Cn onwards, the light is incident on the web w. The light from the light source is blocked. The line sensor outputs a video signal V having a voltage proportional to the amount of light incident on each light receiving element in time series according to a clock signal CK input to the line sensor. The level of the video signal of the light receiving element where the light from the light source is incident without being blocked is Vb, and the level of the video signal of the light receiving element where the light is blocked is Vb.
The level of the video signal changes significantly near the light receiving element Cn corresponding to the edge position of the side end of the web w. Therefore, if there is a level change in the video signal that is greater than the non-uniformity of the video signal due to the sensitivity of the light source or the light-receiving element itself, it can be determined that the side edge of the web w is overlapping the light-receiving element.

Taking into account the non-uniformity of the video signal, the level Vth, which is 70% of Vb, is set as the reference level for determining the presence or absence of an edge, and if it is compared with the video signal Vi of each light-receiving element, the light-receiving elements C1 to Cn- 1 video signal V1
~Vn-1 is larger than the reference level Vth, and the video signal after the light receiving element Cn is smaller than the reference level Vth, so it can be determined that the side edge of the web is located at the position corresponding to the light receiving element Cn. At this time, the rough measured value L1 of the edge position of the side end of the web w expressed in units of pitch (P) of the light receiving element is as follows.

L1=P×(n-1)...(1) Here, to determine the edge position, the number of light-receiving elements on which light is incident is counted, but the number of light-receiving elements that are blocked is also counted. You may.

In reality, the video signal V is output according to the clock signal CK input to the line sensor, so the number of pulses of the clock signal CK starts to be counted at the same time as the line sensor starts outputting the video signal V.
When the magnitude relationship between the video signal V and the reference level Vth begins to reverse, counting of the pulses of the clock signal CK is stopped and the counted value (n) is read, thereby measuring the approximate measured value L1.

Next, measurement of the position L2 of the web side end below the pitch of the light receiving element of the line sensor will be explained. In Fig. 2, the light-receiving element corresponding to the edge position of the side end of the web w is Cn, but the light entering the line sensor from the light source may not be completely parallel light, or the line sensor may not be equipped with an optical system such as a lens. Since the image is blurred when light is incident through the light receiving element Cn
Not only that, but also the video signal of the nearby light-receiving element.
Takes a level between Vb and Vd. Position of web side edge
L2 can be approximately calculated using a linear equation from the video signal of the light receiving element near the edge of the web side. The video signal levels of photodetectors located some distance away from the edge are Vb and Vb, and the photodetector near the edge used for approximate calculation is determined based on the light leakage and image blur in the actual sensor head. In Fig. 2, video signals Vn-1, Vn,
The edge position L2 is obtained from Vn+1 as follows.

L2=P×(aUn-1+bUn+cUn+1)/(Vb -Vb) ...(2) Here, Un-1=Vn-1-Vb; Un=Vn−Vd; Un+1=Vn+1−Vd; a, b, c are counts.

The final edge position L of the web side end is L1 and L2
Based on this principle, the position of the web can be measured with high accuracy.

Next, an embodiment of the web position measuring device according to the present invention will be described with reference to the block diagram of FIG. In FIG. 1, a line sensor 1 receives a scanning signal T from a timing controller 7 and a clock signal CK.
Accordingly, a video signal V near the side of the web running path is output. Upon generation of the scanning signal T, the line sensor 1 starts outputting one line of video signal V, and the video signal V of each light receiving element is output every clock signal CK.

The video signal V is input to the A/D converter 2, and is converted from an analog signal to a digital signal for each light receiving element according to the clock signal CK, and is output as a data signal D. The data signal D output from the A/D converter 2 is temporarily stored in the buffer memory 3. The buffer memory 3 has a capacity to store the data signals D of a plurality of light receiving elements near the edge of the side end of the web, and stores the data signals D in the order in which they are output from the A/D converter 2, and when the storage capacity is filled. , the old data signals D are erased in the order in which they were stored, and new data signals D are stored therein.

While the data signal D is input to the buffer memory 3, it is also input to the comparator 4, and the reference data Vth for determining the presence or absence of an edge is set in advance in the comparator 4, and each time the data signal D is input, Then, the reference data Vth and the data signal D are compared, and when an edge is detected, an edge detection signal E is output.

Here, for example, the light receiving element of the line sensor 1 corresponding to the edge position of the web side end is assumed to be the n-th light receiving element Cn. Let Dn be the data signal of the light receiving element Cn. Therefore, when the data signal Dn is input,
The comparator 4 outputs the edge detection signal E to the counter 5.

The counter 5 counts the pulses of the clock signal CK, and after resetting the count value by inputting the scanning signal T, starts counting the pulses of the clock signal CK, and stops counting by inputting the edge detection signal E. Then, the count value is output as a count signal N. Therefore, the counter 5 is the first one of the image sensor.
Count the number of light receiving elements from the th to the nth,
This means that a rough measurement value of the edge position is being obtained. The count value N is supplied to the CPU section 8.

On the other hand, when an edge is detected by the comparator 4, the buffer memory 3 stores the edge portion and the data signal D of the light receiving elements before and after the edge portion, and holds it for computer processing of precise values. Assuming that the data signals of m neighboring light receiving elements from the light receiving element corresponding to the edge position are used as the light receiving elements before and after the edge portion, the buffer memory 3 stores the data signal D by 2m.
It is sufficient to have the capacity to store +1. When the edge is detected in the comparator 4 and the edge detection signal E is output, the buffer memory 3 stores the data signal Dn−2m from the data signal Dn of the light receiving element corresponding to the edge position to the 2mth previous one. . Therefore, in order to perform precise measurements, the data signal must be further
Data signals from Dn+1 to data signal Dn+m are required, and data signals Di of m light receiving elements need to be input into the buffer memory 3.
Therefore, the edge detection signal E from the comparison section 4 is input to the delay section 6, the delay section 6 counts the clock signal CK m times, and after m data signals Di are input to the buffer memory 3, the delay signal E is inputted to the delay section 6. E′ is output to buffer memory 3. The buffer memory 3 stops storing the data signal Di after the time when the delay signal E' is input. Therefore, data signals Dn-m to Dn+m are held in buffer memory 3 at the time when delayed signal E' is input.

The delayed signal E' from the delay section 6 is also input to the CPU section 8, and a count signal N for rough edge position measurement and data signals Dn-m to Dn+m for precise measurement are output.
The data is transferred to the CPU section 8.

In accordance with the above-mentioned web position measurement principle, the CPU section 8 obtains a rough measurement value of the edge position of the side end of the web,
Performs calculations of precision measurement values. A flowchart of an embodiment of the web position measurement process performed by the CPU section 8 is shown in FIG. Step 10~
In step 12, data necessary for position measurement calculation processing is input from the electronic circuit section, and in step 13, (1)
Rough measurement values are calculated based on the formula, and in steps 14 to 16, precise measurement values below the photodetector pitch are calculated based on formula (2), and in step 17, the above processing is performed. From the results, the edge position L of the web side end is finally determined.

As explained above, according to this embodiment, the position of the web can be measured with higher precision than measurement using a normal line sensor while using a line sensor.

The present invention is not limited to the embodiments described above, and, for example, the calculation processing of precision measurement values is not limited to the processing described above.

〔Effect of the invention〕

As explained above, according to the web position measuring device according to the present invention, when measuring the edge position of the side end of the web using a line sensor, the edge position is roughly measured using an electronic circuit (hardware), and an electronic computer (software) is used to roughly measure the edge position. ), and the final web position is determined by the sum of the two, which simplifies the circuit compared to when everything is done with an electronic circuit, and requires no changes to the calculation formula used for measurement. is easy. In addition, compared to the case where everything is done by computer processing, the program is simpler and requires less memory on the computer side, and it can be processed in a shorter time, so it does not affect other processes of the web guide device. Never give up. In this way, by dividing the measurement between the electronic circuit and computer processing, the processing burden on both sides is reduced.
Measurement is achieved with a simple circuit configuration and a simple computer program. Thereby, it is possible to control the position of the web in the width direction with higher precision.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the web position measuring device according to the present invention, Fig. 2 is a diagram showing the measurement principle, Fig. 3 is a flowchart showing the measuring operation, and Figs. 4 to 6 are the web position measuring device. 1 is a diagram showing a conventional example of a measuring device. 1...Line sensor, 2...A/D converter, 3
... Buffer memory, 4 ... Comparison section, 5 ... Counter, 6 ... Delay section, 7 ... Timing control section,
8...CPU section.

Claims (1)

[Claims] 1. In a web position measuring device that measures the position of the side edge of a web used in a web guide device that controls the widthwise position of a running web in a rotary printing press, the direction in which the light receiving elements are arranged intersects with the running direction of the web. The line sensor means is provided at the side end of the web running path and generates a video signal for each light receiving element, and the light receiving device compares the video signal with a reference signal and inverts the magnitude relationship of both signals. an edge detection means for generating an edge signal according to the position of the element; and a first measuring means for roughly measuring the edge position in units of the pitch of the light receiving element according to the edge signal and the pitch of the light receiving element of the line sensor means. , comprising a second measuring means for precisely measuring the edge position in units smaller than the pitch of the light receiving elements of the line sensor in accordance with the video signals of a predetermined number of light receiving elements near the light receiving element corresponding to the edge signal; A web position measuring device featuring: