JPH018961Y2 - - Google Patents

Description

[Detailed description of the invention] This 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, it is capable of 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. 47-42205), 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 to determine the ink amount. There is a method (for example, Japanese Patent Publication No. 47405/1983) that calculates the sum of the ink 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 usually processed according to the first processing step described below. Here, the development process (step S1) of the normally used positive type printing plate removes the photosensitive layer in the areas exposed to light (non-image areas) and desensitizes it (prevents ink from adhering to the surface). However, any unnecessary photosensitive layer that remains in a portion even after the development process is dissolved by applying an erasing liquid only to that portion (step S3).
Next, the printing plate is dried (step S4), and a surface preparation liquid is applied to the entire printing plate (step S5), and the printing plate is dried by puff drying so that no surface preparation liquid remains on the printing plate surface (step S7). These surface smoothing treatments and puff drying are preparatory steps for the burning (high temperature heating) treatment, and by subsequently performing the burning treatment (step S8), the printing durability of the printing plate can be increased from 2 to 30%.
Improved by 3 times. Finally, a so-called gumming treatment (step S10) is carried out for the purpose of protecting the surface of the non-printing area and further increasing freshness, 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 at a high temperature of 0.degree. C., a typical printing plate based on an aluminum plate for coins is thermally deformed, and even after cooling, the flatness of the plate surface deteriorates, resulting in permanent deformation. 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 idea will be explained below.

In this invention, as shown in FIG. 2, a printing plate 20 is fixedly attached below the movable photoelectric detection devices 10 arranged in a line, and the photoelectric detection devices 10 are moved by a conveying device to be described later. By moving the printing plate 20, detection scanning is performed linearly on the printing plate 20.

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 this calibration mark 23 is used to distinguish between the non-printing area (grained area in A1) 24 and the drawing area (pattern area) 25. It's getting old.
The photoelectric detection device 10 also includes a pair of parallel cylindrical fluorescent lamps 11 and 12 that can form a linear irradiation surface.
In addition, fluorescent lamps 11 and 12 are arranged in a line in the middle as shown in FIG.
Photoelectric detectors 13 of S ₀ , S ₁ , S ₂ , . . . , S _o are provided. However, this photoelectric detector 13 (S ₀ ~
The circuit configuration of the printing _plate 20 is as shown in Figure 4.
A photodiode PD that receives reflected light from the photodiode and undergoes photoelectric conversion, and 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 -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. Therefore, 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 has a slit 16 provided 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 three racks at its upper and lower ends, respectively.
1 and 37 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 porous sheet or a plate having 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 inside and below 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 reflected light from the printing plate 20, and the printing plate 20, which is the object of detection, is as follows, burning processing etc. Detection errors due to unevenness of the printing plate display caused by the above 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. 2K), more preferably 0.35 to 0.70 times
Fluorescent lights 11, 12 by distance X in the range of 0.4 to 0.6 times
The peripheral P of the position on the plate surface of the printing plate 20 that is equidistant from the two fluorescent lamps 11 and 12 is set as a reference position and is set as a detection area, and only the reflected light from the detection area P is received. This is the optimal positional relationship for measurement in which the photoelectric detector 10 is installed facing the printing plate 20, and the effects of light transmission and reception between the photoelectric detector and the printing plate 20 in such a relative position will be explained. do. By the way, fluorescent light 1
Since 1 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, 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. When performing integral calculations assuming that it is the sum of contributions from all point light sources to a surface, 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 sinθ times the illuminance of the surface that is perpendicular to the projection light beam, 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 expressed as 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
There is a difference in illuminance corresponding to the difference between the value when X ₀ and the value when X=X ₀ +ΔX ₀ , and a measurement error corresponding to this difference will occur. By the way, the illuminance I _(X) is a function that has a maximum value at X=K, as shown in Fig. 9, and near the maximum value, the same position deviation ΔX ₀
The change in illuminance I _(X) for Therefore, if the printing plate 20 is installed at the position where X=K and the detection is performed with the detector 10 that detects the detection area P, accurate measurement can be performed even if the printing plate 20 has unevenness. Can be done. Also, 0.8K<X
Even in the range <1.2K, that is, 0.4×2k<X<0.6×2K, the characteristics are almost linear, allowing highly accurate measurement.

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

Place the printing plate 20 on the stage 74 via pins 75 and 76, and turn on the power switch (step S).
1), the suction device 38 operates and the printing plate 20
is closely fixed to the stage 74, the fluorescent lights 11 and 12 are turned on, and the printing machine number and, for example, front printing or back printing in the case of a blanket-to-blanket type printing machine, are entered from the keyboard 47 (step S2). )do. Data set in the ROM 45 is set by these input data. The data of such RAN46 or ROM45 includes the plate size (for example, 1310 mm x 1050
mm, 1160mm x 940mm), number of ink adjustment keys (e.g. 32, 50...), key spacing (e.g. 30mm, 40mm)
), the distance between the key and the edge of the plate (for example, 5 mm,
10mm...) distance between the printing effective area and the edge of the plate (for example, 22mm from top to bottom, 20mm from side to side...), etc. This allows the use range of the photoelectric detector 13 (in Fig. 3)
S ₁ to S _k ), the spacing and number of ink adjustment keys, and other settings are made (step S 3 ), and by pressing the measurement start switch, the motor 34 is driven, and the ink is The scanning device 10A is moved in the M direction or the N direction in FIG. 6A, and the photoelectric detection device 10 built into the scanning device 10A detects and scans the surface of the printing plate 20. Note that the scanning position of the photoelectric detection device 10 is detected by the rotary encoder 36 and
It is sent to the CPU 44 via the bus and the detection position, and the timing of the detection scanning movement is synchronized. 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 passes through the slit 16 again and then passes through the slit in the shielding box 14. Photodiode PD via 15
This is converted into an amount of electricity corresponding to the amount of light. Note that the photoelectric detector S ₀ in Figure 3 varies depending on the power source voltage, ambient temperature, etc. (fluorescent lamps 11 and 12)
This detects changes in the data, and the changes are corrected in subsequent data processing. Also, photoelectric detector
S ₁ detects the non-image area 24 and calibration mark 23 in order to calibrate the upper and lower limits of the amount of reflected light, and the photoelectric detector S _k takes in only the detector output within the printing effective area as data. used for 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), and the multiplexer 42 The detected data selected and output according to the program is converted into digital data by the AD converter 43, and then input to the register of the CPU 44 via the input/output control circuit 49 and the bus (step S5). When data input for a portion corresponding to one ink adjustment key is completed (step S6), the data is transmitted from the register of the CPU 44 to the RAM 46 (step S7). At this time, the calibration mark 2
3 and the detection data of the amount of light from the light source are 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 memorizing the detection data of
The scan is repeated multiple times and stored. This makes it possible to reduce the influence of noise-based errors. A determination is then 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 this 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 by selectively using data such as the ink adjustment key width and number stored in the ROM 45 or RAM 46 corresponding to the printing machine number that has already been set. It is done. The thus 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 .}
In the space defined by 1 ₃ and 1 ₄ , a fluorescent lamp 1
Further effective measurement is possible by providing light shielding plates 81 and 82 that partially block the projected light from 1 and 12. In this case, the setting position X of the printing plate 20
is K<X<1.4K. put it here,
During normal operation, that is, when the printing plate 20 is in a predetermined position, the projected light from the fluorescent lamps 11 and 12 forms an area surrounded by line segments 1 ₁ A, 1 ₂ and 1 ₂ A, 1 ₄ in FIG. There is.

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 1 ₁ B, 1 ₂ A
Since the effective light emitting area of _the light source decreases, 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 of the detection area P can be adjusted in advance by the setting positions of the light shielding plates 81 and 82, and in the end, the measurement error due to the positional displacement of the printing plate 20 can be offset by the illuminance change. Can be corrected. In this case, instead of providing the light shielding plates 81 and 82, it is also possible to position the photoelectric detection device 10 in the above-mentioned spatial region, as shown in FIG. 15, and to use the side plate of the shielding box 14 for the same purpose.

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 area spanning the line segments 1 ₂ and 1 ₄ 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 a light source, a xenon lamp, a neon lamp, a halogen lamp, etc. can also be used, and a phototransistor or the like can also be used as a photoelectric detector.

As described above, the measuring device of this invention can be used regardless of differences in printing plate processing, printing plate brand, lot, and size, as well as thermal deformation distortion of printing plates caused by burnig treatment, etc. It is possible to accurately measure the pattern area without being affected by
Depending on the type of printing press used, measurements can be made for different ink adjustment key widths and numbers. Therefore, a measuring device is not required for each printing machine, and only one printing line needs to be installed.Also, since measurements are taken from printing plates, unlike measurements from transparent originals (film originals), It is not necessary to process measurement data regarding the layout of the printing plate, 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 and inexpensive, and has low accuracy. Highly accurate measurements are possible. Furthermore, in-line automatic measurement on the printing plate line is also possible, and the workload of measurement is small. However,
Image area measurement data can improve the operating rate of the printing press by presetting the ink adjustment key at the start of printing, and not only has the effect of reducing defective prints, but also can be used to estimate the amount of preparation required for special color ink. This method can be applied to other aspects, such as reducing fuel consumption by setting optimal conditions for off-wheel dryers.

On the other hand, the shape of the device is vertical, and
The scanning device is equipped with an input device and an output device, which improves operability and improves work efficiency, reduces work errors such as making dents on printing plates, and reduces device space. It has several advantages. Furthermore, since the detection head (scanning device) is moved, the work area becomes smaller than when the printing plate is moved.

If the printing plate has a positive type resist layer, the irradiation light should be of a wavelength around 650 nm, as this layer is usually green in color and breaks down 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 contrast between the image area and the non-image area, and to make the measured values extremely correct.

Furthermore, the light shielding plates 81 to 84 described in FIGS. 13, 14, and 16 do not need to completely block light; for example, translucent plastic plates may be used.

Furthermore, if the printing plate is configured to be scanned by suctioning and fixing it to a stage, 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 drawings]

Figure 1 is a flowchart showing the printing plate processing process, Figure 2 is a diagram showing the positional relationship between the movable photoelectric detection device and the printing plate according to this invention, and Figure 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 the detection element in the photoelectric detection device, Figures 5A and B are side and front views showing the schematic structure of the photoelectric detection device, and Figures 6A and B are the measuring device of this invention. A front view and a side view showing the external appearance 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 this invention, and FIG. 9 is a printed version. FIG. 10 is a diagram for explaining the optimal relative positional relationship with a fluorescent lamp, FIG. 10 is a diagram showing the relationship between distance , FIG. 12 is a diagram showing an example of printing according to this invention, FIG. 13 is a diagram showing another example of the light receiving section of the photoelectric detection device according to this invention, FIG. 14 is a diagram for explaining its operation, and FIG. The figures show a modification of the device shown in FIG. 13, FIG. 16 shows yet another example of the light receiving section of the photoelectric detection device according to this invention, and FIG. 17 shows 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 Claim for Utility Model Registration] A device for measuring a pattern area from a printing plate for offset printing, comprising: a main body of the device having an inclined front panel; and a large number of through holes provided on the front panel. a stage consisting of a flat plate placed on the stage; a light source for irradiating the printing plate for offset printing placed on the stage with light regulated by a light shielding member; and a photoelectric device for detecting the reflected light from the printing plate for offset printing. a scanning device having a detector; a suction device provided in the main body of the device for suctioning and fixing the printing plate for offset printing through a through-hole in the stage; and a suction device that allows the scanning device to slide freely on the front panel. a support means for supporting the scanning device; a driving device for driving the scanning device so as to slide the scanning device with respect to the front panel; and an input device provided on the top surface of the scanning device for inputting an instruction for measuring a pattern area. , controlling the light source, the suction device, and the driving means based on instructions input by the input device, and calculating the pattern area of the printing plate for offset printing based on the signal obtained from the photoelectric detector. an arithmetic device provided in the scanning device; and an output device provided on the top surface of the scanning device and outputting the calculation results of the arithmetic device. A device for measuring the area of a pattern from a plate.