JPS6352327B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring the area of an image area (picture area) from a printing plate for an offset printing machine, and in particular to a device for accurately detecting unevenness on an offset printing plate. This invention relates to a device for measuring the area of a picture.

By the way, the method to measure the pattern area is as follows.
In addition to the method of measuring the picture area from a printing plate, there are methods that detect proofs, prints from this machine, reflective originals, transparent originals, etc. Additionally, there are some printers that use this measured value to check the density of printed matter during operation of the printer to perform feedback control, and others that preset the ink supply amount before printing. However, in a normal printing plate, the pattern on the printing plate is a pattern formed by arranging a plurality of originals at predetermined positions and printing them. Therefore, when measuring objects other than printing plates and printed matter from this machine,
The disadvantage is that after measuring the area of each individual pattern, 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 the printed matter of this machine, the measurement data can be used immediately, but if you obtain measurement data from the printed matter of this machine, the measurement must be performed after printing has started. This is a feedback control system that corrects fluctuations caused by 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 adjustment key before starting printing, and to print a good product from the time printing starts.

Here, as an example of a device that uses a printing plate as a measuring object, the printing plate is wound around a cylinder and rotated at high speed.
There are methods that measure the average afterimage for each zone (for example, Japanese Patent Publication No. 47-52205), or scan the original plate (printing plate) of an offset printing machine to obtain the number of pulses corresponding to the area of the image area. A device that adjusts the ink supply amount (for example, Japanese Patent Application Laid-open No. 48-53804) detects and integrates the image lines on the printing plate for each ink adjustment key, and uses an auxiliary printing plate to detect the amount of reflected light in the non-image area. , calculates the signal of only the image area from the detection signal of the printing plate,
There are those that adjust the amount of ink by converting it into a value corresponding to the area of the image (for example, Japanese Patent Application Laid-Open No. 49-67714), and those that scan the original in the vertical direction and calculate the occupation rate of the image in the width direction of the original. A device that measures and controls the ink supply amount at the ink source roller section (for example, Japanese Patent Application Laid-Open No. 51-2505) scans a photoelectric detection device vertically at a predetermined position in the horizontal direction of the printing surface or plate surface. There is a method (for example, Japanese Patent Publication No. 47405/1983) that calculates the total amount and adjusts the amount of ink.
However, since none of these devices that detect printing plates can accurately detect printing plates, they have not become practical.
That is, after contact exposure of a transparent film original is carried out, the printing plate is normally processed according to the processing steps shown in FIG. 1, which will be explained next. Here, processing of the phenomenon of normally used positive type printing plates (step S1)
This is done to remove the photosensitive layer in areas exposed to light (non-image areas) and make it desensitized (to prevent ink from adhering to the surface), but some parts may remain even after treatment. Dissolve the unnecessary photosensitive layer by applying erasing liquid only to that part (step
S3). Next, the printing plate is dried (step S4), a surface preparation liquid is applied to the entire printing plate (step S5), and the printing surface is dried by buff-drying so that no surface preparation liquid remains on the printing plate surface (step S7). ). These surface smoothing treatment and buff 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 S10) 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 printing plates, but
Since the printing plate is heated to a high temperature of 0.degree. C., a typical printing plate based on a hard aluminum plate is thermally deformed, and even after cooling, it becomes permanently deformed and the flatness of the plate surface deteriorates. Therefore, when detecting the amount of reflected light to determine the picture area from such a printing plate, the amount of reflected light changes not only depending on the picture area but also depending on the degree of unevenness and misalignment of the printing plate. As a result, accurate detection accuracy cannot be obtained and the ink supply amount cannot be set correctly.

In addition, in places that have a large number of printing machines of various types, it is common for many types of printing plates to be processed in the printing plate process, and the pattern area meter from the printing plate is It is preferable to use the measuring device integrated with the printing plate line at the printing plate site, and to measure data for ink adjustment of multiple printing presses with one measuring device, rather than using the measuring device integrated with the printing press at the printing plate site. Therefore, it is an object of the present invention to provide a picture area measuring device that satisfies such requirements and is free from the above-mentioned drawbacks.

This invention will be explained below.

In this invention, as shown in FIG. 2, a printing plate 20 is fixedly mounted below the movable photoelectric detection devices 10 arranged in a line, and the photoelectric detection devices are transported by a conveying device to be described later. By moving the printing plate 10, 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 21 (edge 22 or part that does not adversely affect printing) of the printing plate. Ori,
Alternatively, a solid part in the drawing area is set as the mark, and the calibration mark 23 is used to distinguish the non-printing area (Al grain part) 24 and the drawing area (pattern area) 25. I'm starting to do that. Further, the photoelectric detection device 10 includes a pair of parallel cylindrical fluorescent lamps 11 and 12 that can form a linear irradiation surface, and the fluorescent lamps 11 and 12
In the middle of the photodetector 13, photodetectors 13 _S0 , _S1 , _S2 , . . . , _S0 are arranged in a line as shown in FIG. However, this photoelectric detector 13 (S ₀
~S _o ) circuit configuration is shown in Figure 4, printing plate 2
A photodiode PD that receives reflected light from 0 and converts it photoelectrically, an operational amplifier OP that uses this output as one input (the other input is grounded),
It consists of a resistor R and a capacitor C connected between the input and output of this operational amplifier OP. The structure of the photoelectric detector 13 (S ₀ to S _o ) is as shown in FIGS. 5A and 5B, in which a photodiode PD for photoelectric detection is attached to the upper end of a cylindrical shielding box 14.
At its lower end there is a slit 15 that receives reflected light.
is provided. Thus, a light shielding box 17 is provided which encloses the slit 15 portion of the shielding box 14, shields the fluorescent lamps 11 and 12, and is provided with a slit 16 at the bottom for receiving reflected light from the printing plate 20. This light-shielding box 17 is partitioned by a partition plate 18 for each detector.

Here, the actual configuration of such a photoelectric detection device 10 is shown in FIG.
The front panel 71 has an inclined surface, and has racks 3 at its upper and lower ends, respectively.
1 and 73 are provided, and a stage 74 for mounting the printing plate 20 is arranged in the center of the front panel 71. In addition, printing version 20
is positioned by pins 75 and 76, and is attracted to the stage 74 by a suction device 38, which will be described later. Further, the stage 74 is made of a multi-optical sheet or a plate with a large number of small holes. A box-shaped scanning device 10A is disposed between the racks 31 and 73, and includes the above-mentioned photoelectric detection device 10 and a necessary circuit configuration. A keyboard 47 and a printer 48 are provided. Note that the printing plate 20 is connected to this scanning device 1.
It is designed to be inserted between the scanning device 10A and the stage 74, and by moving the scanning device 10A in the M and N directions shown in the figure, the photoelectric detection device 10 disposed in the lower part of the scanning device 10A detects the printing plate. 20 is line-scanned.

Further, as shown in FIG. 7, the scanning mechanism of the scanning device 10A consists of racks 31 and 73 provided along the upper end of the front panel 71 and a pinion 32 that engages with the racks. Therefore, the scanning device 10A supported by the guide rail 72 is moved. Here, the pinion 32 is rotatably driven by a motor 34 via a gear mechanism 37, and a rotary encoder 36 for detecting the position of the scanning device 10A is attached to the gear shaft. Note that a suction device 38 consisting of a suction pump or the like is provided below the stage 74 to suction the printing plate 20 mounted thereon.

On the other hand, the arithmetic processing unit 40 that calculates the picture area from the detection signal includes an amplifier circuit 41 (A ₀ to A _o ) for amplifying the detection signal from the photoelectric detector 13 for each detection element, as shown in FIG. , a multiplexer 42 for selectively outputting the signal from this amplifier circuit 41 according to an arithmetic processing program, and a multiplexer 42 for converting the output of this multiplexer 42 into a digital signal.
AD converter 43, CPU 44, ROM (read only memory) 45 and RAM as a storage device
(random access memory), a keyboard 47 for inputting data and other required numerical values,
a printer 48 that prints out the results of the arithmetic processing;
It is composed of an input/output control device 49 that controls input/output between the AD converter 43 and the CPU 44 and others, and includes an input/output control device 49, a CPU 44, a ROM 45,
The RAM 46, keyboard 47, and printer 48 are interconnected via a bus. Further, the output of the rotary encoder 36 is input to the CPU 44 via a reading circuit 50 and a bus.

In such a configuration, if the relative positional relationship between the photoelectric detector 10, the fluorescent lamps 11 and 12, which detect the amount of light reflected from the printing plate 20, and the printing plate 20, which is the detection target, is set as follows, the burning process can be performed. Detection errors due to unevenness on the printing plate surface caused by such causes 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 FIG. 0.35-0.70 times the distance (2K), more preferably
Fluorescent lamp 11 by a distance (x) in the range of 0.4 to 0.6 times,
12 as a reference position, a detection area P around a position on the printing plate surface of the printing plate 20 that is equidistant from the two fluorescent lights 11 and 12, and only the reflected light from the detection area P is received. This refers to the optimal positional relationship for measurement in which the photoelectric detector 10 is placed opposite the printing plate 20 so that The effect of light transmission and reception between the photoelectric detection device 10 and the printing plate 20 having such a relative positional relationship will now be described. Incidentally, since the fluorescent lamps 11 and 12 are linear light sources, their illumination intensity 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, but in the case of a line light source, the illuminance of a certain surface is considered to be a linear light source gathered in a line, and the illuminance of a certain surface is inversely proportional to the square of the distance from the light source. If an integral calculation is performed assuming that the illuminance is the sum of the contributions of all point light sources to the light source, the illuminance is inversely proportional to the distance from the light source. On the other hand, the illuminance of a surface that is not perpendicular to the projected light beam is sin θ times the illuminance of the surface that is perpendicular, where θ is the angle between the surface and the perpendicular surface. Therefore, the illuminance I in the detection area P in FIG. 8 is I _(x) = A·x/K ² +x ² (1) where A is a proportionality constant. Now, assuming that the printing plate 20 is placed at a predetermined position x ₀ , and if the positional deviation due to unevenness on the surface of the printing plate 20 is ΔX ₀ , then the value when x=x ₀ in the above equation (1) is , there is a difference in illuminance corresponding to the difference from the value when x=x ₀ +Δx ₀ , and a measurement error corresponding to this difference will occur. Incidentally, the illuminance I _(x) is a function having a maximum value at x=K as shown in FIG. 9, and near the maximum value, the change in the illuminance I _(x) for the same positional deviation Δx ₀ becomes small. Therefore x=K
If the printing plate 20 is installed at a position where the detection area P is detected by the detector 10 that detects the detection area P, accurate measurement can be performed even if the printing plate 20 has irregularities. Also, 0.8K<x<1.2K,
In other words, even in the range of 0.4×2k<x<0.6×2k, the characteristics are almost linear, allowing highly accurate measurement.

The operation of such a configuration will be explained with reference to the flowchart of FIG. 11.

Place the printing plate 20 on the stage 74 via the pins 75 and 76, and turn on the power switch (step
S1), the suction device 38 is activated and the printing plate 2
0 is closely fixed to the stage 74, the fluorescent lights 11 and 12 are turned on, and the keyboard 47 is used to input the printing machine number, front printing or back printing in the case of a blanket-to-blanket type printing machine, etc.
(step S2). Data set in the ROM 45 is set by these input data. Such RAM46 or ROM4
The data for 5 is the size (for example, 1310mm x
1050mm, 1160mm x 940mm......), number of ink adjustment keys (e.g. 32, 50...), key spacing (e.g. 30mm, 40mm...), distance between the key and the edge of the plate (e.g. 5mm, 10mm……), the distance between the printing effective area and the edge of the plate (e.g. 22mm from top to bottom,
20mm left and right...) etc. As a result, the usage range of the photoelectric detector 13 (S ₁ to S _k in FIG. 3), the interval and number of ink adjustment keys, etc. are set (step S3), and the motor 34 is driven by pressing the measurement start switch. , the scanning device 10A is moved in the M direction or the N direction in FIG. Detection scanning will be performed. Note that the scanning position of the photoelectric detection device 10 is detected by the rotary encoder 36, and is detected by the rotary encoder 36 and transmitted through the reading circuit 50 and the bus.
The signal is sent to the CPU 44, and the timing of the detection position and detection scanning movement are matched. Here, the irradiation light from the fluorescent lamps 11 and 12 in the photoelectric detection device 10 passes through the slit 16 to the printing plate 20.
(or the stage 74), and the reflected light passes through the slit 16 again, and further passes through the slit 15 of the shielding box 14, and reaches the photodiode PD, where it is converted into an amount of electricity corresponding to the amount of light. In addition, the third
The photoelectric detector S ₀ shown in the figure 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 S ₁ 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 S _k detects the detector output within the printing effective area. It is used to capture only the data as data. Note that the photoelectric detector for performing calibration is not limited to _S1 in FIG. 3, and can be freely selected 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 photoelectric detection device 10 (step
S4), the detection data selected and output by the multiplexer 42 according to the program is converted to digital data by the AD converter 43, and then input/output control circuit 4
9 and the bus to the register of the CPU 44 (step S5). When the data input for the part corresponding to one ink adjustment key is completed (step S6), the data is input from the register of the CPU 44.
Data is transmitted to RAM 46 (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 output from each photoelectric detector 13 is selectively outputted by the multiplexer 42, and after AD conversion, it is stored in the address of the RAM 46 corresponding to the detection target (calibration mark, pattern, light source), but only once. Rather than storing the detected data, the scan is repeated multiple times and stored. This makes it possible to reduce the influence of noise-based errors. Then, a determination is made as to whether or not the number of all ink adjustment keys has been imported (step S8), and if the ink has been imported, after that determination, the calibration and light source light intensity are corrected by arithmetic processing of the data in the RAM 46. , the total picture area, area ratio, and picture area 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 4 according to the printing machine number that has already been set.
This is done by selectively using data such as the width and number of ink adjustment keys stored in 5 or the RAM 46. In this way, the determined picture area and area ratio are printed out by the printer 48 (step
S10). An example of this printing form is shown in FIG.

By the way, in the above-mentioned embodiment, the photoelectric detection device 10
, the fluorescent lamps 11 and 12, and the printing plate 20.
9 and 10. However, as shown in FIG. 13, the boundaries of the detection area P and the line segments l ₁ and l ₂ surrounding the fluorescent lamps 11 and 12 are arranged as shown in FIGS. and l ₃ and l ₄ , a light shielding plate 81 that partially blocks the projected light from the fluorescent lamps 11 and 12,
82, even more effective measurement is possible. In this case, the set position x of the printing plate 20 is K<
x<1.4K. Here, in a steady state, that is, when the printing plate 20 is in a predetermined position, the projected light from the fluorescent lamps 11 and 12 is divided by the line shown in FIG.
The area is surrounded by l ₁ A, l ₂ and l ₂ A, l ₄ .

Here, if the setting position of the printing plate 20 is shifted upward as shown in FIG. When the plates 81 and 82 are provided, the light from the fluorescent lamps 11 and 12 is transmitted to l ₁ B, l ₂ A and
Since the effective light emitting area of the light source decreases by changing to the range of l ₃ B and l ₄ A, the illuminance within the detection area P also decreases. Therefore, the displacement distance of the printing plate 20 and the degree of change in illuminance in the detection area P can be adjusted in advance by the set positions of the light shielding plates 81 and 82, and the measurement error due to the positional displacement of the printing plate 20 can be offset by the offset effect of the illuminance change. It can be corrected. In this case, instead of providing the light shielding plates 81 and 82, the photoelectric detection device 10 as shown in FIG.
is located in the above-mentioned spatial area, and the shielding box 14 is
It is also possible to use the side plate for both purposes.

On the other hand, when the distance x of the printing plate 20 is 0.7K<x<K, it is sufficient to provide light shielding plates 83 and 84 in the spatial region spanning the line segments _l2 and _l4 , as shown in FIG.
Instead of the light-shielding plates 83 and 84, the bottom plates 17A and 17B of the light-shielding box 17 can be made longer and used also as shown in FIG. 17. In this case, the illuminance during normal operation is low, and when the position of the printing plate 20 shifts upward, the illuminance increases and correction is performed.

In the above embodiment, the position of the photoelectric detection device is determined using a rotary encoder to determine the timing of detection, but a pulse motor is used as the motor.
The photoelectric detection device can be moved by a CPU timing pulse, or the photoelectric detection device can be moved at a constant speed by a servo motor, a synchronous motor, etc., and the detection timing can be determined by a timer. Further, although a fluorescent lamp is used as the light source, a xenon lamp, a neon lamp, a halogen lamp, or the like may also be used, and a phototransistor or the like may also be used as the photoelectric detector.

As described above, according to the measuring device of the present invention, it is possible to measure the thermal deformation distortion of the printing plate caused by the burning process, etc., regardless of the differences in the processing of the printing plate process or the brand, lot, and size of the printing plate. It is possible to accurately measure the pattern area without being affected by this, and it is also possible to perform measurements that correspond to the width and number of ink adjustment keys that vary depending on the type of printing press used. Therefore, a measuring device is not required for each printing press, and only one device needs to be installed on the printing plate line.Also, because the measurement is taken from the printing plate, it is different from the measurement from a transparent original (film original), etc. , the device is simple and low-cost because it does not require processing of measurement data regarding the layout of the pattern, and the relative position between the printing plate and the detection device is less susceptible to mechanical errors in the device or deformation of the printing plate; Highly accurate measurement becomes possible. Furthermore, in-line automatic measurement on the printing plate line is also possible, and the workload of measurement is small. Therefore, the image area measurement data can not only improve the operating rate of the printing press by presetting the ink adjustment key at the start of printing, and also have the effect of reducing defective prints, as well as help prepare special color inks. It can be applied in many ways, such as estimating the amount of water and reducing fuel consumption by setting optimal conditions for off-wheel dryers.

In addition, if the printing plate has a positive type resist layer, the irradiation light should be of a wavelength around 650 nm because this layer is usually green in color and this layer disintegrates in the wavelength range of 350 to 500 nm. It is desirable to do so. By doing so, it is possible not only to avoid collapse of the resist layer, but also to improve the optical cost of the image area and the non-image area, and to optimize the measured values.

Furthermore, the light shielding plates 81 to 84 described in FIGS. 13 and 16 do not need to completely block light; for example, translucent plastic plates may also be used.

Furthermore, if the printing plate is configured to be suctioned and fixed to the stage for scanning, even if the printing plate becomes noticeably uneven due to baking or the like, the distance between the light source and the printing plate can be reduced to 0.35 to 0.70 of the distance between the light sources. This makes it possible to more reliably set the detection value within the double range, thereby achieving even higher accuracy of the detected value.

[Brief explanation of the drawing]

Fig. 1 is a flowchart showing the printing plate processing steps, Fig. 2 is a diagram showing the positional relationship between the movable photoelectric detection device according to the present invention and the printing plate, and Fig. 3 is a state of detection scanning by the photoelectric detection device. Figure 4 showing
The figure is a circuit diagram showing an example of the configuration of a detection element in a photoelectric detection device, FIGS. 5A and B are side and front views showing the schematic structure of the photoelectric detection device, and FIGS. 6A and B are a diagram of a measuring device of the present invention. Front view and side view showing the external configuration,
Fig. 7 is a diagram showing a part of the mechanism in detail, Fig. 8 is a block diagram showing an example of the configuration of the arithmetic processing device according to the present invention, and Fig. 9 explains the optimal relative positional relationship between the printing plate and the fluorescent lamp. FIG. 10 is a diagram showing the relationship between distance x and illuminance to provide an explanation thereof, FIG. 11 is a flowchart showing an example of the operation of the apparatus according to the present invention, and FIG. 12 is a diagram showing an example of printing according to the present invention. 13 is a diagram showing another example of the light receiving section of the photoelectric detection device according to the present invention, FIG. 14 is a diagram for explaining its operation, and FIG. 15 is a modification of the device in FIG. 13. FIG. 16 is a diagram showing still another example of the light receiving section of the photoelectric detection device according to the present invention.
FIG. 7 is a diagram showing a modification thereof. 10... Photoelectric detection device, 11, 12... Fluorescent lamp, 13... Photoelectric detector, 14... Shielding box, 1
5, 16...slit, 17...shading box, 18...
...Partition plate, 20...Printing plate, 21...Bite, 22
...Bite end, 23... Calibration mark, 24... Non-printing area, 25... Printing area (printing effective area), 31 and 73... Rack, 32... Pinion, 34... Motor , 36... rotary encoder, 37... gear mechanism, 38... suction device,
40...Arithmetic processing unit, 41...Amplification circuit, 42
...Multiplexer, 43 ...AD converter, 44
... CPU, 45 ... ROM, 47 ... keyboard, 48 ... printer, 49 ... input/output control device, 50 ... reading circuit, 71 ... front panel, 7
2...Guide rail, 74...Stage, 75,
76...Pin.

Claims (1)

[Scope of Claims] 1. Two linear light sources parallel to each other for irradiating light onto a detection area of a printing plate for offset printing, and a linear light source above the detection area for receiving reflected light from the detection area. a photoelectric detection device provided, and a device for measuring a pattern area of the printing plate based on an output from the photoelectric detection device, wherein a plane including the two linear light sources and a plate surface of the printing plate are connected to each other. parallel to each other, and the distance between both planes is 0.4 to 0.6 times the distance between the two linear light sources, and the detection area is equidistant from the two linear light sources. , the printing plate is arranged, a light shielding plate is prepared between the linear light source and the detection area, and when the detection area is displaced in a direction approaching the linear light source, the increase in the amount of displacement is An apparatus for measuring a pattern area from a printing plate for offset printing, characterized in that the light shielding plate is installed at a position such that an effective light emitting area of the linear light source with respect to the detection area is reduced accordingly. 2 The light-shielding plate is composed of two parallel flat plates placed perpendicular to the plate surface of the printing plate, and these two parallel flat plates are placed between two linear light sources so that the light shielding plate becomes parallel to the linear light source. 2. The apparatus according to claim 1, wherein the lower ends of the two linear light sources are substantially aligned with the lower ends of the two parallel flat plates. 3. The device according to claim 2, wherein the light shielding plate constitutes the tip of the envelope of the photoelectric detection device.