JPS644124B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection head of a picture area measuring device for measuring the area of an image area (picture part) from a printing plate for an offset printing machine.

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. 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, the development process of the normally used positive type printing plate (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 remain even after development. 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. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a detection head for 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 detection head 10 comprising movable photoelectric elements arranged in a row
A printing plate 20 is fixedly mounted below the printing plate 20, and detection scanning of the printing plate 20 is carried out in a linear manner by moving a detection head 10 using a conveyance device to be described later.

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 portion 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 (A1 grain area) 24 and the drawing area (picture area) 25. It's becoming like that. The detection head 10 also includes a pair of parallel cylindrical fluorescent lamps 11 and 1 that can form a linear irradiation surface.
2, and the fluorescent lights 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 converts it into electricity, 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 to S _o ) is as shown in FIGS. A photodiode PD is installed to receive the reflected light RP from the printing plate 20, and
On the opposite side of the PC, circuit elements (such as resistors, operational amplifiers, and capacitors) CD are fixed to process the light reception signal from the photodiode PD. A slit 15 is provided in the lower part of the shielding box 14 to receive the reflected light RP, and further below the slit 15 position, the slit 15 is wrapped around the slit 15 and the fluorescent lamps 11 and 12 are shielded.
and slit 16 for accepting reflected light RP.
A light-shielding box 17 is provided at the bottom. Further, a partition plate 18 for partitioning the optical path is provided between the detection part of the calibration mark 23 of the shielding box 14 and the part for detecting the pattern.

Here, the actual configuration of the detection head 10 is shown in FIGS. 6A, B, and C, and the front panel 71 of the measuring device main body 70 is a vertical slope with an inclination. Guide rails 72 and 73 are provided at the end and lower end, respectively, and a printing plate 2 is provided at the center of the front panel 71.
A stage 74 having a convex structure for mounting the 0 is arranged. In addition, the printing plate 20 has pins 75 to 7.
The stage 74 is positioned by a suction device 38, and is also attracted to a stage 74 by a suction device 38. Also,
The stage 74 is made of a porous sheet or a plate with a large number of small holes. Therefore, the above-mentioned detection head 1 is located between the guide rails 72 and 73.
A scanning device 10A having a box-like concave structure and containing a necessary circuit configuration is slidably disposed. The printing plate 20 is inserted between the scanning device 10A and the stage 74, and the scanning device 10A is connected to the scanning rope 3.
By driving the printing plate 20 to move it in the M and N directions shown in the figure, the detection head 10 disposed inside 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 operation input device, for example, a keyboard 47, for specifying and inputting the operation of the scanning device 10A.
An output device, such as a printer 48, is provided for displaying the results of scanning by scanning device 10A.

As shown in the figure, the scanning mechanism of the scanning device 10A has its top 10B fixed to the scanning rope 31 wound around a driving roller 91 and an auxiliary roller 92 arranged at both ends of the upper part of the front panel 71. By rotating the drive roller 91 with a separate drive motor 93, the guide rail 72,
73 in the M and N directions. 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 suction pump etc. for sucking the printing plate 20 mounted below the stage 74. A suction device 38 is provided.

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 and CPU (microprocessor)
44, a ROM (read only memory) 45 and a RAM (random access memory) 46 as storage devices, a keyboard 47 for inputting data and other necessary numerical values, and a printer 48 for printing out the results of arithmetic processing. , the above AD converter 4
3 and an input/output control device 49 that controls input/output with the CPU 44 and others.
9, CPU 44, ROM 45, RAM 46, keyboard 47, and printer 48 are mutually connected 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 addition, DH in Figure 7
A portion of the head 10 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, 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 due to unevenness on the surface of the printing plate caused by this 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 detection head 10 is placed opposite the printing plate 20 so that The effect of light transmission and reception between the detection head 10 and the printing plate 20 in 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, 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 surface, 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 detection head 10 that detects the detection area P, accurate measurement can be performed even if the printing plate 20 has irregularities. Also, 0.8K＜x＜
Even in the range of 1.2K, that is, 0.4×2K<x<0.6×2K, the characteristics are almost linear, allowing highly accurate measurements.

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

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 plate size (for example, 1310mm
×1050mm, 1160mm×940mm…), number of ink adjustment keys (e.g. 32, 50…), key spacing (e.g. 30
mm, 40 mm...), the distance between the key and the edge of the plate (for example, 5 mm, 10 mm...), the distance between the printing effective area and the edge of the plate (for example, 22 mm from top to bottom, 20 mm from side to side, 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 drive roller 91 is driven by the sprocket 32 of the gear mechanism 37, the sprocket 91' of the drive roller 91, and the endless chain 32' stretched thereon.
The scanning device 10A is moved in the M direction or the N direction in FIG. 6B via the scanning rope 31, and the scanning device 10
A detection head 10 built in A 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 illumination light from the fluorescent lamps 11 and 12 in the detection head 10 passes through the slit 16 to the printing plate 20 (or stage 7).
4) The reflected light RP reaches the top and returns to slit 1.
6 and further passes through the slit 15 of the shielding box 14 to reach the photodiode PD, where it is converted into an amount of electricity corresponding to the amount of light. Note that the photoelectric detector _S0 in FIG. 3 detects changes in the amount of light from the light source (fluorescent lamps 11, 12) due to power supply voltage, ambient temperature, etc., and the changes are corrected in subsequent data processing. In addition, the photoelectric detector S ₀ is connected to the non-image area 24 in order to calibrate the upper and lower limits of the amount of reflected light.
and the calibration mark 23, and the photoelectric detector S _k is used to take in only the detector output within the printing effective area as data. Note that the photoelectric detector for performing calibration is not limited to _S0 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 detection head 10 (step
S4) The detection data selected and output by the multiplexer 42 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 the 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 S6).
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).
Rather than storing detection data once, multiple scans are repeated and stored. 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 is complete, 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 processing of the detection data corresponding to the ink adjustment key will be performed 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 the ROM 45 or RAM 46. The picture area and area ratio thus determined are printed out by the printer 48 (step S10). An example of this printing form is shown in the 11th example.
As shown in the figure.

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. 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 many optical sensors are selected by a multiplexer, AD converted, and then transmitted, making it resistant to noise and reducing the number of transmission lines. It has the advantage of requiring less. 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. By doing so, 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. Another advantage is that even if the arrangement interval of the ink adjustment keys is changed, it can be easily accommodated by simply changing the preset information for obtaining the measurement timing. 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 beginning of printing, but 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 the optimal conditions for off-transfer 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 contrast between the image area and the non-image area, and to optimize the measured values.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the printing plate processing process, FIG. 2 is a diagram showing the positional relationship between the movable detection head and the printing plate according to the present invention, and FIG. 3 is a diagram showing the state of detection scanning by the detection head. 4 is a circuit diagram showing a configuration example of the detection element in the detection head, FIGS. 5A and 5B are side views and front views showing the schematic structure of the detection head of the present invention, and FIGS. 6A, B, and C. 7 is a front view, a plan view, and a side view showing the external configuration of a measuring device using the detection head of the present invention, FIG. 7 is a block diagram showing an example of the configuration of an arithmetic processing device according to the present invention, and FIG. FIG. 9 is a diagram for explaining the optimal relative positional relationship with a fluorescent lamp, FIG. 9 is a diagram showing the relationship between distance x and illuminance, and FIG. 10 is a flowchart showing an example of the operation of the device according to the present invention. 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, 15,1
6... Slit, 17... Light shielding box, 18... Partition plate, 20... Printing plate, 21... Biting, 22... Biting end, 23... Calibration mark, 24
... Non-printing area, 25... Drawing area (printing effective area),
32...Sprocket, 34...Motor, 36...
...Rotary encoder, 37...Gear mechanism, 38
... Suction device, 40 ... Arithmetic processing device, 41 ...
Amplifier circuit, 42... Multiplexer, 43...
AD converter, 44...CPU, 45...ROM, 4
7...Keyboard, 48...Printer, 49...
Input/output control device, 50...Reading circuit, 71...Front panel, 72, 73...Guide rail, 74...
...Stage, 75, 76...Pin.

Claims (1)

[Claims] 1 In a device that irradiates light while scanning a detection area of a printing plate for offset printing and measures the pattern area of the printing plate from the amount of reflected light, a plurality of optical sensors that receive the reflected light are aligned and mounted on a detection head. A circuit element for processing data signals output from each of the optical sensors is fixed to the support plate, and the circuit element processes data signals output from each of the optical sensors using a multiplexer. It includes a data transmission circuit that sequentially selects the data, converts it into a digital signal, and transmits it later, and further includes a head position detector that detects the position of the detection head during scanning, and the position information from this position detector is converted into preset information. and a data processing device that obtains measurement timing from the coincidence and processes the data signal from the data transmission circuit in correspondence with the arrangement position of each ink adjustment key of the offset printing machine. Image area measurement device for printing plates.