JPH0373802A - Equipment for measuring pattern area ratio of offset printing plate - Google Patents

Abstract

PURPOSE:To quickly measure the area ratio of a pattern by setting up a range to be used fro measurement based upon preset information by means of plural optical sensors included in a detecting head prior to the measurement of the pattern area ratio and using a reflected light quantity measured value for finding out the pattern area ratio. CONSTITUTION:A printing plate 20 is fixed to the lower part of the detecting head 10 consisting of plural movable photoelectric elements formed like a straight line and the detecting head 10 is moved by a carrying device to execute the linear detecting scanning of the printing plate 20. A rectangular calibration mark 23 is attached to a gripper tail 22 (a gripper-end 21 or a part exerting no bad influence upon printing) of the printing plate 20 to be used and a non-image line part 24 is discriminated for a pattern part 25 by the mark 23. Prior to the measurement of the area ratio of the pattern part 25, the range to be used for the measurement is set up by plural optical sensors S1 to Sn included in the detecting head 10 based upon preset information stored in a ROM and the pattern area ratio is found out by using a reflected light quantity measuring value obtained from the set optical sensors S1 to Sn, so that the processing speed of measurement can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for printing printing plates for offset printing presses.
The present invention relates to a picture area ratio measuring device for measuring the Ifivi ratio of a picture area).

By the way, as methods for measuring the picture area ratio, in addition to the method of determining the picture area ratio A#1 from the printing plate, there are methods that use proofs, prints from this machine, reflective originals, transparent originals, etc. as detection targets. . Furthermore, there are methods that use this measurement value to check the density of printed matter during operation of the printing press and perform feedback control, and methods that preset the ink supply amount before printing.

However, in a normal printing plate, the pattern on the printing plate is a pattern obtained by arranging a plurality of manuscripts at predetermined positions and printing them. Therefore, when measuring objects other than printing plates and printed matter from this machine, there is a drawback that, after measuring the individual picture area ratios, the measurement data must be compiled based on the layout on the printing plate. On the other hand, if you measure a printing plate or printed matter produced by this machine, you can use the measurement data immediately, but when you obtain measurement data from printed matter produced by this machine, you cannot measure it after printing has started. Because of this, it becomes a feedback control system that corrects fluctuations due to disturbances during printing. On the other hand, when obtaining measurement data from a printing plate, the purpose is to preset the opening degree of the ink: J3 adjustment key before starting printing, and to print non-defective products from the time printing starts.

Here, an example of a device that measures a printing plate is a device that wraps the printing plate around a tube and rotates it at high speed to measure the average afterimage of each zone (for example, Japanese Patent Publication No. 47-4222
No. 5), and those that scan the original plate (printing plate) of an offset printing machine and apply pulses corresponding to the area ratio of the printed area, thereby adjusting the ink supply amount (for example, Japanese Patent Laid-Open No. 48-53
No. 804), the image on the printing plate is detected and integrated for each ink adjustment key, and the amount of reflected light in the non-image area is detected using the Kamisuke printing plate, and the signal of only the image area is obtained from the detection signal of the printing plate. One that calculates and converts the ink amount into a value corresponding to the area ratio of the drawing line (for example, Japanese Patent Laid-Open No. 49-67741), and another that scans the original in the vertical direction and calculates the drawing line in the width direction of the original. A device that measures the occupancy a and controls the ink supply amount at the ink source roller section (for example, Japanese Patent Application Laid-Open No. 51-2505), a photoelectric detection device is installed at a predetermined position in the horizontal direction of the printing surface or plate surface in the vertical direction. A device that calculates the total amount of ink by scanning the ink and adjusts the amount of ink (for example, the
7405).

However, since none of these devices that detect printing plates can accurately detect printing plates, they are not practical.

That is, after contact exposure of a transmission film original, the printing plate is normally processed according to the processing steps shown in FIG. 1, which will be described next. Here, the development process (step S3) of the normally used positive type printing plate removes the photosensitive layer in the areas exposed to light (non-print areas) and desensitizes it (prevents ink from adhering to the surface). However, any unnecessary photosensitive layer that remains in a part even after the development process is dissolved by using an empty can of erasing liquid only in that part (step S3).

Next, the printing plate is dried (step S4), and a leveling liquid is applied to the entire printing plate (step S5), and the printing plate is dried by puff drying so that no leveling liquid remains on the printing plate surface (step S7). . These surface smoothing treatment and puff drying are preparation steps for the burning (high-temperature heating) treatment, and by subsequently performing the burning treatment (step S8), the printing durability of the printing plate is improved by two to three times. Finally, a so-called gumming treatment (step 510) is performed for the purpose of protecting the surface of the non-image area and further increasing hydrophilicity, thereby completing the printing plate treatment process. In such processing steps, burning treatment is extremely effective for improving the printing durability of the printing plate, but since the printing plate is heated at a high temperature of 250°C to 300'C, it results in a hard aluminum plate. Ordinary printing plates based on this material undergo thermal deformation, resulting in permanent deformation even after cooling, resulting in deterioration of the flatness of the plate surface. Therefore, if the amount of reflected light is detected to determine the picture area ratio from such a printing plate, the amount of reflected light will not only change depending on the picture area ratio but also change depending on the degree of unevenness and misalignment of the printing plate. Accurate detection accuracy cannot be obtained and the ink supply amount cannot be set correctly.

In addition, in places where a large number of printing machines of various types are maintained, it is common for many types of printing plates to be processed in the printing plate process, and the pattern area ratio meter from the printing plate is Rather than being integrated with the printing machine at the printing site, it is used integrated with the printing plate line at the printing plate site, and one single constant device can handle the ink of many printing machines. It is preferable to measure data that undergoes J adjustment. Therefore, an object of the present invention is to provide a picture area ratio measuring device that satisfies such requirements, and particularly to improve the processing speed of measurement.

This invention will be explained below.

In this invention, as shown in FIG. 2, a printing plate 20 is fixedly mounted below a detection head 10 consisting of movable photoelectric elements arranged in a row. By moving the detection head 10 in the apparatus, detection scanning of the printing plate 20 is performed linearly.

Therefore, the printing plate 20 used here has a calibration mark 23 in a rectangular or other shape on the edge 22 (edge 21 or a part that does not adversely affect printing) of the printing plate. , or a solid part in the drawing area is set as the mark, and the non-printing area (Al grain part) 24 is set by this calibration mark 23.
and the drawing area (picture area) 25.

Further, the detection head 10 is equipped with a pair of parallel cylindrical fluorescent lamps 11 and 12 that can form a linear irradiation surface, and a middle part of the fluorescent lamps 11 and 12 is provided with a light beam as shown in FIG. 5O1St, S2.・・・ ・
..., Sn photoelectric detectors 13 are provided. As shown in FIG. 4, the circuit configuration of this photoelectric detector (SO to Sn) includes a font diode PD that receives reflected light from the printing plate 20 and converts it into electricity, and a calculation that uses the output from one side. Amplifier (other power is grounded) OP
and a resistor R connected between the input and output of this operational amplifier OP.
and a capacitor C. In addition, photoelectric detector 1
3 (SO to Sn), as shown in FIGS. 5(A) and 5(B), a photodiode PD for photoelectric detection is mounted on a printed circuit board PC disposed at the upper end of a cylindrical shielding box 14. is attached to receive the reflected light RP from the printing plate 20, and on the opposite side of the printed circuit board PC are circuit elements (for example, resistors, operational amplifiers, capacitors) for processing the light reception signal from the photodiode PD. The CD is stuck. A slit 15 is provided at the lower end of the shielding box 14 to receive the reflected light RP.
Further downward from the 15 position, the printing plate 2 wraps around the slit 15, shields the fluorescent lights 11 and 12, and
A light-shielding box 17 is provided with a slit 16 at the bottom for receiving reflected light RP from 0.

Further, a partition plate 18 is provided between the detection part of the calibration mark 23 of the shielding box 14 and the part for detecting the pattern to partition the optical path.

Here, the actual configuration of such a detection head 10 is shown in FIGS. 6(A), (B), and (C), and the front panel 71 of the measuring device main body 70 is a vertical inclined surface. Guide rails 72 and 73 are provided at the upper and lower ends, respectively, and a convex stage 74 for mounting the printing plate 20 is arranged at the center of the front panel 71. ing. Note that the printing plate 20 is positioned by pins 75 to 78, and the suction device 38
It is designed to be attracted to the stage 74. Also,
The stage 74 is made of a porous sheet or a plate with a large number of small holes.

A scanning device 10A having a box-like concave structure containing the above-mentioned detection rod 10 and a necessary circuit structure is slidably disposed between the guide rails 72 and 73. The printing plate 20 is inserted between the scanning device 10A and the stage 74, and the scanning device 10A is driven by the scanning lobe 31 as shown in the figure.

By moving the printing plate 20 in the N direction, the detection head 10 disposed in the lower part of the printing plate 20 scans the printing plate 20 in a line. Further, near the side of the stage 74 on the front panel 71, there is an operating device such as a keyboard 47 for specifying the operation of the scanning device 10A, and a manual operation device for manually controlling the operation of the scanning device 10A.
An output device, for example a printer 48, is provided for displaying the results of the scan by A.

Therefore, the scanning mechanism of the scanning device 10A is as shown in the figure.
Drive rollers 91 arranged at both ends of the upper part of the front panel 71
The top part 10B of the scanning rope 31 is fixed to the scanning rope 31 wound around the auxiliary roller 92, and by rotating the driving roller 11 by a separate driving motor 93, the scanning rope 31 is slid on the guide rail 72° 73 in the M and N directions. It is designed to move.

Note that a rotary encoder 36 for detecting the position of the scanning device 10A is attached to the rotating shaft of the drive roller 91, and a rotary encoder 36 for detecting the position of the scanning device 10A is attached below the stage 74.
A suction device 38 consisting of a suction pump or the like for adsorbing zero is provided.

On the other hand, arithmetic processing unit 4 calculates the picture area ratio from the detection signal.
As shown in FIG. 7, 0 indicates an upper width circuit 41 (AO to
An), a multiplexer 42 that selectively outputs the signal from the amplifier circuit 41 according to an arithmetic processing program,
An AD converter 43 for converting the output of the multiplexer 42 into a digital signal, a CPU (microprocessor) 44, a ROM (read only memory) 45 and a RAM (random access memory) 46 as storage devices, and data and other components. It is composed of a keyboard 47 for manually inputting required numerical values, etc., a printer 48 for printing out the results of arithmetic processing, and an input/output control device 49 for controlling input/output between the AD converter 43, CPU 44, and others. Human output control device 49, CPU 44, ROM 45, R
The AM 46, keyboard 47, and printer 48 are connected to each other via a bus. In addition, the rotary encoder 36
The output is inputted to the CPU 44 via the reading circuit 50 and the bus. Note that the DH section shown in FIG. 7 is fixed to a printed circuit board PC within the head 10.

In such a configuration, if the relative positional relationship between the detection head 10, the fluorescent lamps 11 and 12, which detect the amount of reflected light from the printing plate 20, and the printing plate 20, which is the detection target, is set as follows, it is possible to perform burning processing, etc. Detection errors caused by unevenness on the surface of the printing plate can be reduced.

That is, the above-mentioned "relative positional relationship" means that the fluorescent lamps 11 and 12 are arranged parallel to the printing plate 20 as shown in the eighth factor, and the printing plate 20 has a distance M between the centers of the fluorescent lamps 11 and 12.
(2K) 0.35 to 0.70 times, more preferably 0.
Fluorescent lamp 11.1 by distance M (X) in the range of 4 to 0.6 times
2 and set it as a reference position, and set the two fluorescent lights 11
．． The detection head 10 is set so as to face the printing plate 20 so as to receive only the reflected light from the detection area P, with the detection area being the periphery P of the position on the printing plate surface of the printing plate 20 that is equidistant from the detection area P. This refers to the optimal positional relationship for M. The effect of stepwise light reception between the detection head 10 and the printing plate 20 in such a relative positional relationship will now be described. By the way, since the fluorescent lamps 11 and 12 are linear light sources, their illuminance is inversely proportional to the distance from the light source. In other words, in the case of a point light source, it is inversely proportional to the square of the distance from the light source, so in the case of a line light source, it can be thought that the point light sources are gathered in a line to form a line light source, and the illuminance of a certain surface is If an integral calculation is performed assuming that the illuminance is the sum of the contributions of all point light sources, the illuminance is inversely proportional to the distance from the light source. On the other hand, the illuminance that is not perpendicular to the projected light beam is expressed as
The illuminance on the perpendicular surface is sin θ times the illuminance. Therefore, the eighth
The illuminance I in the detection area P in the figure is 1 (X)-A-X/ (K2+X'')-----where A is a proportionality constant.
−−・−(1). Now, place the printing plate 20 at the predetermined position
If the positional deviation due to unevenness on the surface of the printing plate 20 is ΔXO, then in the above equation (1),
There is a difference in illuminance corresponding to the difference between the value at Xo and the value at X-X0+ΔXO, and a measurement error corresponding to this difference occurs. By the way, illuminance 1 (X) is a function that has a maximum value at <X-K as shown in Fig. 9, and near the maximum value, illuminance 1 (X
) changes will be small. Therefore, if the printing plate 20 is placed in a position corresponding to X-, and the detection head 10 detecting the detection area P is used for detection, even if the printing plate 20 contains the same song, accurate measurement can be performed. I can do it. Also,
0.8K<X<1.2, that is, 0.4x2K<X<0
．． In the range of 6x2, the characteristics are almost linear, allowing highly accurate measurements.

The operation of this configuration will be explained with reference to the flowchart in FIG.

When the printing plate 20 is placed on the stage 74 via the pins 75 and 76 and the power switch is turned on (step S2), the suction device 38 is activated and the printing plate 20 is tightly fixed on the stage 74, and the fluorescent lamp 11 and 12 are turned on, and the printer number and the distinction between front printing and back printing in the case of a blanket-to-blanket type printing machine, etc., are entered manually from the keyboard 47 (step S2). The data set in the ROM 45 is set by these manual data. The data in the RAM 46 or ROM 45 includes the plate size (for example, 1310 mm x 1050 mm).
, 1160 + am ,...), the distance # between the printing effective area and the edge of the plate (for example, the top and bottom 22
am, left and right 201BF...), etc. As a result, the usage range of the photoelectric detector 13 (Sl -3k in Fig. 3)
, the spacing and number of ink adjustment keys, etc. are set (step S3), and by pressing the measurement start switch, the motor 34 is driven, and the sprocket 32 of the gear mechanism 37 is driven.
, the drive roller 91 is driven by the sprocket 91' of the drive roller 91 and the endless chain 32' stretched thereon,
The scanning device 10A is connected to the scanning device 10A via the scanning rope 31 as shown in FIG. 6(B).
The detection head 10 built into the scanning device 10A detects and scans the surface of the printing plate 20. The scanning position of the detection head 10 is detected by the rotary encoder 36 and sent to the CPU 44 via the reading circuit 50 and the bus, so that the detection position and the timing of the detection scanning movement are matched. Here, the irradiated light from the fluorescent lamps 11 and 12 in the photoelectric detection device 10 passes through the slit 16 and reaches the printing plate 20 (or the stage 74), and the reflected light RP passes through the slit 16 again and further passes through the shielding box 14. The light reaches the photodiode PD through the slit 15 and is converted into an amount of electricity corresponding to the amount of light. In addition,
The photoelectric detector SO in FIG. 3 detects changes in the amount of light from the light source (fluorescent lamps 11 and 12) due to power supply voltage, ambient temperature, etc., and the changes are corrected in subsequent data processing. In addition, the photoelectric detector SO detects the non-image area 24 and the calibration mark 23 in order to calibrate the upper and lower limits of the amount of reflected light, and the photoelectric detector Sk detects only the detector output within the printing effective area as data. It is used to incorporate as. Note that the photoelectric detector for performing the calibration is not limited to the SO shown in FIG. 3, and can be selected as a self-made one depending on the calibration position.

Thus, when the position information output from the rotary encoder 36 matches the edge position information of the printing plate set during the program, the amount of reflected light from the printing plate 20 is detected by the detection head 1.
The detection data detected at AD 0 (step S4) and selectively output by the multiplexer 42 according to the program is
After being converted into digital data by the converter 43, it is input to the register of the CPU 44 via the input/output control circuit 49 and the bus (step S5). When the data input for the portion corresponding to one ink adjustment key is completed (step S6), data is transferred from the register of the CPU 44 to the RAM 46.
The data is transmitted to (step S7). At this time, the detection data of the calibration mark 23 and the amount of light from the light source are also processed in the same way. In this way, the outputs from each photoelectric detector 2!13 are selectively outputted by the multiplexer 42, and the AD
After conversion, it is stored in the address of RAM 46 corresponding to the detection target (calibration mark, pattern, light source).
Instead of storing the detection data for the first time, the same regression is repeated and stored multiple times. This makes it possible to reduce the influence of noise-based errors. Then, it is determined whether or not the number of all ink adjustment keys has been imported (step S8), and if the import has been completed, the RAM is
Calibration and light source light intensity are corrected through calculation processing of the data in 46, and the total cypress pattern area, area ratio, and pattern area ratio for each ink adjustment key are determined (step S9). In this case, the detection data corresponding to the ink adjustment key is processed in the ROM 45 or R according to the already set printing machine number.
This is done by selectively using data such as ink: J84i key width and number stored in AM46. The picture area and area ratio thus determined are printed out by the printer 48 (step 510). An example of this instant form is shown in FIG.

As described above, according to the measuring device of the present embodiment, prior to the measurement of the picture area, the detection head 10 stores the range to be used for measurement in the plurality of white light sensors S1 to Sn in the ROM4.
Set based on the preset information set in 5.
Since the pattern area ratio is determined using the measured value of the amount of reflected light from the set optical sensor, the processing speed of Al1 constant can be improved.

In addition, the image area ratio can be accurately measured regardless of differences in printing plate processing, printing plate brands, lots, and sizes, and without being affected by heat deformation distortion of printing plates caused by burning processing, etc. At the same time, the 'Ap1 setting corresponding to the ink adjustment key width and number, which differs depending on the type 8 printing machine used, can be carried out. Therefore, a measuring device is not required for each printing machine, and only one device needs to be installed on the printing line.Also, because the measurement is taken from the printing plate, it is different from measuring from a transparent original (film original), etc. There is no need to process measurement data regarding the layout, and the relative position between the printing plate and the detection device is not affected by mechanical errors or deformation of the printing plate, so the device is simple, inexpensive, and highly accurate. Measurement becomes possible. In addition, since the circuit elements of the detection head are mounted on the support plate inside the detection head, it is easy to downsize, and in the data transmission circuit, the outputs of a large number of optical sensors are selected by a multiplexer before the AD Since it is converted and transmitted, it has the advantage of being resistant to noise and requiring fewer transmission lines. In addition, the measurement timing is obtained from the position information signal from the head position detector that detects the position of the detection head during scanning, and the data signal from the data transmission circuit is processed in correspondence with the arrangement position of each ink adjustment key. , it is now possible to perform measurements while scanning and moving the detection head without fixing it at the measurement position, which has the effect of shortening the measurement time accordingly. There is also an advantage that even if the arrangement intervals of , ink, and ifi keys are changed, it can be easily accommodated by simply changing the preset information for obtaining lpj constant timing. Furthermore, automatic in-line measurement on the printing plate line is also possible, which reduces the workload of measurement. Therefore, by presetting the ink adjustment key at the printing start of the printing press based on the measurement data of the pattern area ratio, it is possible to improve the operating rate of the printing press, which not only has the effect of reducing defective printed matter, but also has the effect of reducing the number of defective prints. It can be applied to many fields, such as estimating quasi-am in ink and reducing fuel consumption by setting optimal conditions for off-wheel dryers.

In addition, when the printing plate has a positive type resist layer, since this layer is usually green in color and this layer collapses in the wavelength range of 350 to 500 nm,
It is desirable that the fish/I light has a wavelength around 650 nm. By doing so, it is possible not only to avoid collapse of the resist layer, but also to improve the optical contrast between the image area and the non-image area, and to optimize the measured values.

As explained above, according to the present invention, prior to measuring the picture area ratio, the range to be used for measurement in the plurality of optical sensors included in the detection head is set based on preset information, and the reflection from the set optical sensor is set. Since the pattern area ratio is determined using the measured value of the light amount, the processing speed of the measurement can be improved.

[Brief explanation of drawings]

Figure 1 is a flowchart showing the printing plate processing process;
The figure shows the positional relationship between the movable detection head and the printing plate according to the present invention, Figure 3 shows the state of detection scanning by the detection head, and Figure 4 shows the configuration of the detection cable in the detection head. A circuit diagram showing an example, FIGS.
), (B), and (C) are a front view, a plan view, and a side view showing an example of the external configuration of the measuring device according to the present invention, FIG. 7 is a block diagram showing an example of the configuration of the arithmetic processing device according to the present invention, and FIG. is a diagram for explaining the optimal phase χ (positional relationship) between the printing plate and the fluorescent lamp, FIG. FIG. 11 is a flowchart showing an example of the operation of this invention, and FIG. 11 is a diagram showing an example of printing according to the present invention. 10...Detection head, 11.12...Fluorescent lamp, 13
...Photoelectric detector, 14...Shielding box, 15.16...
・Slit, 17... Light-shielding box, 18... Partition plate, 2
0...print version, 21...bite, 22...bite butt,
23... Calibration mark, 24... Non-printing area, 25... Printing area (printing effective area), 36...
Rotary encoder, 38... Suction device, 40...
Arithmetic processing unit, 41... Amplification circuit, 42... Multiplexer, 43... AD converter, 44... CPU,
45...ROM. 47...keyboard, 48...printer, 49...
- Human output control device, 50... Reading circuit, 71... Front panel, 72.73... Guide rail, 74...
Stage, 75.76...pin.

Claims (1)

[Claims] A detection head having a light source that irradiates light onto a detection area of a printing plate for offset printing and a plurality of optical sensors that receive reflected light from the detection area, and the detection head is moved relative to the printing plate. A picture area ratio measuring device for a printing plate for offset printing, comprising a driving means and a signal processing means for determining a picture area ratio of the printing plate using a measured value of reflected light amount obtained from an output signal of the optical sensor. The signal processing means sets a range to be used for measurement in the plurality of optical sensors based on preset information of the printing plate to be measured, and calculates a pattern area ratio using the measured value of the amount of reflected light from the set optical sensors. A device for measuring a pattern area ratio of a printing plate for offset printing, characterized in that: