JPH0429965B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention uses a measuring device with a plurality of sensors, and the calibration of each individual sensor is divided into at least one calibration with a minimum and maximum dot coverage. This invention relates to a method and apparatus for determining the dot area ratio of a printing press original or plate by using a strip.

[Prior Art] A system is known from US Pat. No. 3,958,509 for pre-calculating an ink zone adjustment screw adjustment value of a printing press. The dot area ratios of two calibration plates, one for 0% calibration and the other for 100% calibration, are measured using one electronic camera, and these values are stored. In the next step of measurement, the halftone dot area ratio of the area with ink and the area without ink is measured for the plate to be examined. Since these measured values vary depending on the material of the plate, it is necessary to calibrate the sensor. Therefore, these measurements are matched with the previously measured values of the two calibration plates, and the corrected measured values are stored. The adjusting screws of the ink zones are adjusted according to these corrected measured values.

Further, West German Patent Publication DE-OS 2950606 describes a device for photoelectronically measuring the dot area ratio of an original image for each zone. The idea is that the distribution of the bright areas of the original is examined by means of detection elements and fed to a computer, which then outputs a corresponding signal for adjusting the ink zone screws. These systems, which predetermine the amount of adjustment of the ink zone adjustment screws, require automatic calibration of the measuring device to balance variations in the illumination and receiver elements as well as all analogue electronics, as well as to account for differences in the light reflection properties of the plates to be measured. The disadvantage is that there is no automatic calibration for In addition, in lighting using an arc tube, fluctuations in light intensity related to the power supply frequency are extremely disadvantageous since scanning for measurement is desired to be as fast as possible. Further, handling is difficult because it is not easy to deal with differences in plate size and plate type. Moreover, these systems are technically very cumbersome, expensive and complex in the case of large and low printing, and the pre-adjustment of the ink supply of the printing press reduces the occurrence of paper waste and shortens the make-up time. The investment required to realize this hope is not economically justified.

[Problems to be Solved by the Invention] An object of the present invention is to provide a printing press original drawing or plate plate that balances fluctuations in illumination devices, light receiving devices, etc. and automatically calibrates differences in light reflection characteristics of plates to be measured. The object of the present invention is to provide a method for determining the halftone area ratio.

[Means for Solving the Problem] According to the present invention, this object is achieved in the first claim.
The problem is solved by the features described in Sections 1 and 10.

[Function] The present invention aims at ease of handling the device and reproducibility of the measurement results in measuring the profile of the dot area ratio of a printing plate or an original. Furthermore, it seeks to ensure flexibility in dealing with differences in the type of original and its plate size, which is expected to result in significant cost savings. Furthermore, the high precision ensures that the printing press can be pre-adjusted.

A notable advantage is the detection of several reference measurement points in a calibration field with a maximum dot area and a calibration area with a minimum dot area, which are specifically provided on the original image. This arises from the fact that the calibration is corrected by

One advantage is the automatic status confirmation function,
It consists of various things. That is, 1. Is the calibration strip present and is its position accurate?
Function 2 to monitor whether the length is correct; function 3 to confirm the existence of a calibration field on the plate or original; function to check the type and size of the plate or original.

The presence and correct position of the calibration strip is determined by monitoring the order of the surfaces with the smallest dot coverage and the surfaces with the greatest dot coverage. That the calibration strip is of the correct length for the plate or original is determined by determining the measurements by one or more sensors taking into account the contrast between the plate mounting surface and the calibration strip. The existence of a calibration field is confirmed by detecting the minimum and maximum measurements within the calibration area or field on the plate or original. The type of plate or original is known by examining the magnitude of the measurements in the calibration field and calibration area, in particular in relation to the measurements on the calibration strip. The plate size of a plate or original is automatically obtained by measuring the change in contrast between the plate-bearing surface and the plate or original.

In order to aim for high measurement accuracy and thereby improve the quality of the presetting of the printing press, the minimum and maximum dot coverage on the printing plate or original can be determined advantageously in the absence of a calibration field on the printing plate or original. The measured element values of are determined by the sensor of the measuring device, the other measured values are normalized to these values, and the dot area ratio of the original or plate is thereby determined individually. It will be done. It is advantageous to have an illumination device in the measuring device consisting of an arc tube whose temporal fluctuations in light intensity are smoothed out, which makes it possible to achieve high measuring speeds. By means of a distribution plate placed in front of the illumination device, better, ie more even, illumination of an area of the printing form, for example the width of the ink zone, can be achieved. By using a polarizing filter and a dispersion film in the measurement head, the effects of brightness caused by ambient light can be suppressed.

In a preferred embodiment of the invention, the photoreceiver is assembled from sensors, the signals of the individual sensors being routed via a multiplexer to an amplifier for amplification and then digitized for storage using an analog/digital converter. be done. The operational functions and execution of calculations are taken care of by one computer integrated in the operating desk. A safety roller provided on the measuring device is particularly advantageous, as this prevents the original from becoming uneven and being damaged. A calibration field mask is provided to facilitate mounting the calibration field on a variety of different plates.

[Example] Next, an example of the present invention will be described using the drawings.

Figure 1 shows the plate mounting surface 1 and the guide path 6
2 shows the measuring device 7 in motion. There is a crosspiece 10 projecting above the plate mounting surface 1, and this is arranged at right angles to the measuring crosspiece 12. In the figure, the horizontal abutting bar 10 has, for example, 32 measuring zones 11 according to the zone classification of the ink grooves of the printing machine.
The vertical measuring bar 12 is divided into, for example, 22 measurement zones 11 depending on the number of sensors. The plate 2 with the plug hole 63 of the alignment and tensioning guide rail is positioned in the center of the scale within the area of the plate 2 with respect to the abutment bar 10 on the plate support surface 1. Above the printing form 2 there is a calibration area 20 with an inked surface 3 and a calibration field 4 as well as a measuring line 46 . Furthermore, above the printing surface 1, to the left of the vertical calibration bar 12, there is a calibration strip 64, the area 6 on the left of which is for the minimum calibration of the ink build-up, and the area 5 on the right with the maximum ink build-up. It is divided for calibration purposes. Inside the measuring device 7, as shown in FIG. 2, 22 sensors 9 and one additional sensor 8 are housed. Inked surface 3, calibration field 4 and calibration area 2
Find the value of 0 ink. Inside the measuring device 7 there is a lighting device 14 having two arc tubes 51, and the arc tubes 51 are fixed with a support 65.
In the light emission region from the arc tube 51 towards the printing plate surface 1 there is a dispersion plate 15, which dispersion 15 may also be constituted by a polarizing filter 40. sensor 9 is 1
The matching electronic circuit 47 is located above the two focusing lenses 18 and directly above the measuring slit 19.
is combined with There is also a polarizing filter 58 and a dispersion film 39 in this reflection optical path. Plate 2 not measured by sensors 8 and 9
And the surface of the calibration strip 64 is defined by the measuring slit 19 and the partition plate 29 of the light-tight box. The measuring device 7 is driven by a motor (not shown) via a toothed belt and moves along the guide path 62. A safety roller 16 is fixed to the lower part of the measuring device 7 with a support 17. FIG. 3 shows the individual operating elements (information transmittable and display for the operator) 21 to 55, which are arranged on the panel 13 of the plate reading device for carrying out the measuring process. ing. For example, the order of operations is as follows. A calibration strip 64, preferably made of the same material as the plate, is placed to the left of the plate 2 on the plate support surface 1. Then, the power switch 25 is used to put the device into operation. By means of the button 80, a vacuum is generated in the corresponding range of the vacuum slit 38, which is selectively used depending on the size of the plate on the surface of the plate mounting surface 1. This vacuum first attracts the calibration strip 64. Next, place the plate 2, making sure that the plug holes 63 of the positioning and tension guide rails are on the upper edge of the plate mounting surface 1, and that the left plate end of the plate 2 is aligned with the abutting crosspiece 10. It should come into the first measurement zone 11 and be centered between the first measurement zone and the end measurement zone. Heidelberg Printing Machine Manufacturing Co., Ltd. Marking line 32 indicating the nominal width of the standard plate
Makes it easier to set up the plates. At this stage, the driver selects in advance the type of information transmission, recording, and erasure by operating buttons.The buttons are 52 for the type of information transmission, 53 for the type of recording, and 54 for the type of deletion. . Drivers can choose from numerical, graphical, and test records. By pressing the information sending button 24, the driver can cause the record printing device 22 to print on the recording paper 23 and send it out. The most important type of information transmitted by the plate reading device is an automatically readable data medium, such as a cassette 55. A set of color separated plate measurements are stored in this cassette 55. This set 55 is then read by an input device, preferably at the console of the printing press. The ink requirement data is then converted into machine preconditioning data. The plate dimensions for plate 2 are 27 in width and 28 in length. Code entry switch 26
Set with . The settings are input by entering a number, and the plate 2 that is placed covers the abutting bar 10 and the measuring bar 12 up to this number. The stroke of the measuring device 7 is determined by the set printing width.
The plate size set by the code input switch 26 is stored by operating the plate size input button 45. The color separation selection button 31 selects the color of the plate 2 on which it is placed, for example, black, cyan, magenta, yellow, or two additional colors X and Y. Air suction for the plate 2 is activated by means of the vacuum generation button 30. At this time, air suction is limited to the vacuum slit 38 selected according to the size of the plate. When the start button 33 is pressed, the measurement run begins. The measuring operation begins with the measurement of area 6 for minimum calibration and area 5 for maximum calibration, then the measurement moves to plate 2, where starting with the first measurement zone 11 and during the plate of plate 2 set Go to the corresponding zone accordingly. The measuring device 7 returns to the starting point over the printing plate surface 1 at a faster speed than on the outward journey. When the information sending button 24 is operated, the selected type of information is sent. It is also possible to carry out measurements of other plates 2 in the color-separated set before that. Paper feed button 21 is for recording paper 23
It serves to send the information to the recording/printing device 22. Other functions available to the driver are activated by selectively operating the emergency stop button 37, the emergency start button 36, and the return button 35. This is used to select color separations and/or exclude calibration fields. The specially provided additional sensor 8 is switched off with the calibration sensor disconnect button 34. FIG. 4 schematically shows the flow of signals inside the measuring device 7. The individual components include focusing lens 18, sensors 8 and 9, matching electronics 47, multiplexer 48 and amplifier 49. The measuring device 7 is driven by a motor with a transmission (not shown in the figures). For example, an inductive detector provides the basis for positioning the measuring device 7 on the printing plate surface 1. A counter and a comparator, which are advanced by the pulses received from the pulse-emitting disk, determine the location from which the measuring device 7 transmits the measured value. The measurement is carried out while the measuring device 7 is continuously traveling over the printing plate surface 1. The measurements are directed to an A/D converter 50 located within the signal processing electronics of the device. The light reflected from plate 2 is received by sensors 8 and 9 via a focusing lens 18, processed by matching electronics 47, passed through a multiplexer 48 to an amplifier 49, and then to an A/D converter 5.
0. In order to optimally utilize the resolution of the A/D converter 50, the amplification factor of the amplifier 49 is adjusted to the maximum signal of the sensor 9 in the region 6 for minimum calibration of the calibration strip 64. That is, the amplifier 49 is adjusted so that the minimum measured value and the maximum measured value are located in the lower and upper detection regions of the amplifier 49, respectively. If it falls below the minimum number of conversion digits of the available converter, the offset coupling of the amplifier 49 is varied relative to the measured value of region 5 for maximum calibration of the calibration strip 64. That is, the input signal of the amplifier 49 is mixed with another signal. If there is an adverse effect between the offset setting and the amplifier setting due to circuit constraints, the amplifier is optimized again.
When this process is performed, it may be necessary to perform a new calibration measurement before the actual measurement operation. Within a set of color-separated plates after the first plate, the calibration and measurement steps are generally carried out alternately.

Individual sensors 8 and 9 on calibration strip 64
Calibration is performed. The contrast relationship between the calibration strip 64 and the printing plate 2 is obtained by means of an additional sensor 8 over the calibration area 20 on the printing plate 2 . Then, by means of special mathematical operations, the previously obtained calibration curves of sensors 8 and 9 are adapted to the relationship of plate 2. If the dot area ratio is smaller than 0% in any measurement zone on the plate 2, it means that there is a calibration error due to a defect in the calibration measurement surface. The minimum calibration should be replaced with this value as well. That is, negative measured values are replaced with equal to zero.

In order to minimize the difference between the contrast relationships of the plate 2 and the calibration strip 64, the calibration strip 64 is preferably made of a material corresponding to the plate 2. If the calibration strip 64 is different, it is also possible to make this discoverable, for example by means of a specially provided calibration strip memory in the measuring panel. The operator visually compares the plate 2 and the calibration strip 64, measures the most suitable calibration strip 64, and places it in the measurement position on the measurement panel. By this measure it is achieved that the light receiving device is calibrated in the subsequent working area of the plate 2. This will have implications for recalibration for optimal resolution and measurement accuracy. This is particularly useful if the additional sensor 8 has to be switched off by actuation of the calibration sensor disconnect button 34, possibly due to the absence of a calibration field or if the calibration field 20 and/or the calibration field 4 is defective. It is.

FIG. 5 shows a film 56 for making a calibration strip 64. The two regions 41 and 42 correspond to the minimum and maximum dot area ratios, respectively. The mark line 43 serves as a mark when cutting the plate according to its length. For example, the distinguishing corner 44 of the film 56 is cut off in the case of an aluminum plate, and left as is in the case of a multilayer metal plate. For measurements without automatic confirmation of the plate type, a calibration strip 64 is placed on the plate mounting surface 1.
The micro switch provided in the area of the calibration strip 6
4, thereby confirming the type of plate.

The calibration field microphone 60 shown in FIG. 6 has a window 59 for copying the calibration field 4 in the case of negative copying. In order to provide a calibration field of view 4 for positive copying, a calibration field of view microphone 5 as shown in FIG.
7 is used. Calibration field of view microphone 57 or 60
may be made of any material. A calibration field mask made of board is especially useful.

In order to obtain a dimensionally compliant copy of the calibration field 4 on the plate 2, a corresponding calibration field mask 57 or 60 is applied.
is, in this particular example, the upper right corner of plate 2,
In other words, it is installed at the printing end so as to cover it.
This is because there are no holes in this location. Copying the calibration strip 64 in the print direction of the plate is particularly important if the plate 2 has a particular direction of extreme shine (such as when brushed). In principle, it would also be possible to incorporate luminance reduction means in the measuring device 7, for example a dispersion film 39, or to insert a polarizing filter 40 in the optical path of the measuring slit 19 and/or the illumination device and the light receiver. Compared to aluminum plates, multilayer metal plates have a greater amount of light reflected from the ink-filled plate. This requires inversion of the measurement signal. For the device, when a calibration strip is placed, a specially provided microswitch is activated automatically to signal this, or this is done automatically by the plate type verification function described above. The additional sensor 8 can be switched off, in particular by means of the calibration sensor disconnect button 34, when the calibration field 4 is abnormal or not present at all. Setting the plate size may be done automatically in other embodiments other than the method using the code input switch 26 described above. In this case, the sudden change in contrast from the plate mounting surface 1 to the plate 2 is determined by the sensor 9 in the vertical direction (plate length direction) and by the sensor 8 or 9 in the horizontal direction (plate width direction).
What is obtained by measurement by the measuring device 9 is the dot area ratio per zone. The basic thing here is the surface area determined by the zone width and the number of sensors.
It is. In general, the length of the print, which is related to the plate size, is not the same as on the surface of this base. An automatic correction of the measured value to the 100% standard is therefore performed.
This is done by multiplying the measurement result by a constant that has been entered in relation to the plate size. Even with this dot coverage, it is not possible to directly pre-adjust the ink supply of the printing unit. Therefore, pre-adjustment values for the ink groove (zone opening) and doctor (ink streak width) are calculated from this value of the dot area ratio in relation to the machine type and the ink. This takes place in particular on the operating panel of the printing press, but in principle it could also be done by the computer of the plate reading device.

It is also possible to provide a special preconditioning calculator. Such a presetting calculator with a corresponding presetting value calculation program makes possible the widespread use of presetting value data for all printing presses within the range of normal plate sizes. It becomes possible. Such a pre-adjustment calculator would also make it possible to rewrite the zone spacings and zone widths associated with an ink groove, which are programmed in the plate reading device, to match other ink grooves. From the halftone area ratio data, per sheet of paper,
For web paper, the amount of ink required per unit length and the thickness of the ink layer on the sheet of paper can be calculated. This allows the amount of ink required for one publication to be estimated in advance.

[Effects of the Invention] As described above, the present invention detects the calibration area of the original drawing or plate using a sensor, thereby obtaining a correction value specific to the original drawing or plate, and correcting the calibration of all sensors. By doing so, the lighting device,
This has the effect of balancing variations in the light receiving device, etc., and automatically calibrating differences in light reflection characteristics of plates to be measured.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the arrangement of the calibration strip and plate on the plate mounting surface, and also shows the measuring device, Fig. 2 is a vertical cross-sectional view of the measuring device, Fig. 3 is a layout of the operation buttons of the plate reading device,
Figure 4 shows the components of the measuring device and the signal flow, Figure 5 shows the film used to create the calibration strip, and Figure 6 shows the calibration field mask with a window placed over the negative plate (negative copy). ), and FIG. 7 is a diagram showing a windowless calibration field mask (positive copy) placed over a positive plate. 1... Plate mounting surface, 2... Plate, 3... Ink application surface, 4... Calibration field of view, 5... Area for maximum calibration, 6... Area for minimum calibration, 7... Measurement. device, 8...additional sensor, 9...sensor,
10...Abutting crosspiece, 11...Measurement zone, 12...
...Dimensioning crosspiece, 13...Panel of plate reading device, 14
...Illumination device, 15...Dispersion plate, 16...Safety roller, 17...Support, 18...Focusing lens, 1
9...Measurement slit, 20...Calibration area, 21...
...Paper feed button, 22...Record printer, 23...
Recording paper, 24...Information sending button, 25...Power switch, 26...Code input button, 27...
Print width symbol, 28...Plate length symbol, 2
9... Partition plate, 30... Vacuum generation button, 31...
...Color separation selection button, 32...Mark line, 33...Start button, 34...Calibration sensor disconnect button, 35...Return button, 36...Restart button, 37...Emergency stop button, 38...Vacuum Slit, 39... Dispersion film, 40... Polarizing filter, 41... Area of minimum surface concealment, 42...
...Area of maximum surface obscurity, 43...Mark line, 44...
... Corner for identification, 45 ... Plate size input button, 46
...Measuring line, 47...Matching electronic circuit, 48
...Multiplexer, 49...Amplifier, 50...
A/D converter, 51... Arc tube, 52... Information transmission type selection button, 53... Recording type selection button, 54... Erase type selection button, 55... Cassette, 56... Film, 57... Calibration field mask, 58...Polarizing filter, 59...Window, 60
... Calibration field mask, 62 ... Guide path, 63 ...
Alignment and tension guide rail plug holes, 6
4... Calibration strip, 65... Support.

Claims (1)

[Scope of Claims] 1. A plate mounting surface 1 that supports an original drawing or a plate, and a plurality of sensors arranged above the printing plate mounting surface 1 so as to be movable in translation above the original drawing or plate, and adjacent to each other. 9, and a measuring device 7 for detecting reflected light.
The calibration is carried out using the measurements of at least one calibration strip 64, which is placed on the printing surface 1 and has the portions of the minimum and maximum dot area, before each dot area is determined. In the method of determining the dot area ratio of a printing press or plate, which is carried out, while determining the dot area ratio of the original or plate 2, the original or plate having at least one of the minimum and maximum dot area ratio is 2 calibration areas 4, 20, 46 are scanned by one of the sensors 9 or by a sensor 8 added in the measuring device 7 and calibrated by a calibration strip 64, thereby determining the area characteristic of said original or plate. A correction value is obtained, and the calibration of all sensors 9 is corrected in accordance with the correction value,
A method for determining the dot area ratio of an original drawing or plate for a printing press. 2 The measuring device 7 measures the calibration field 4 on the original or plate 2 and the calibration area 20 along the measuring line 46.
The calibration field 4 with the maximum dot coverage and the measuring line 46 are used to calibrate each sensor 8, 9 to the same value.
2. A method as claimed in claim 1, in which one or more reference measurement points are detected within a calibration region 20 having a minimum dot coverage along the . 3 The measuring device 7 first performs an automatic status check of the presence and correct position of the calibration strip 64 and determines the surface area with the minimum dot area and the area with the maximum dot area. 3. The method according to claim 1 or 2, wherein the method is carried out by monitoring the order in which surface portions having . 4 The calibration strip 64 is of the correct length for the plate or original by one or more sensors 9.
4. The method according to claim 1, wherein the measurement value is determined by taking into account the contrast between the printing plate mounting surface 1 and the calibration strip 64. 5. The presence of the calibration field 4 is ascertained by the measuring device 7 by detecting the minimum and maximum measured values in the calibration field 20 or in the calibration field 4 on the original or plate 2. Items 1 to 4
The method described in any one of paragraphs. 6. Claims 1 to 5 in which the type of plate or original is known by examining the magnitude of the measurements in the calibration field 4 and the calibration area 20, in particular in relation to the measurements in the calibration strip
The method described in any one of paragraphs. 7. Any one of claims 1 to 6, wherein the plate size of the plate or original drawing 2 is automatically obtained by measuring the change in contrast between the plate mounting surface 1 and the plate or original drawing 2. The method described in section. 8. The minimum and maximum measurements of the dot coverage are determined by one or more sensors 9 of the measuring device 7 without a calibration field.
on the original 2 itself, all measured values are normalized to these values, and the dot area ratio of the original or plate is likewise determined individually. A method according to any one of claims 1 to 7. 9 The light emitted by the illumination device 14 in the measuring device 7 is reflected on the individual areas of the plate or original, and this reflected light is converted into an analog signal by the sensor 9 of the measuring device 7 in accordance with the dot coverage. converted into a signal,
This signal is sent to multiplexer 48 and amplifier 49
8, which is supplied to the analog/digital converter 50 via a
The method described in section. 10 A measuring device 7 including a plate mounting surface 1 supporting an original drawing or a plate, and a plurality of adjacent sensors 9 arranged above the printing plate mounting surface 1 so as to be movable in translation above the original drawing or plate. and
A calibration strip 64 with the minimum and maximum portions of the dot area ratio is provided on the printing surface 1, and while the dot area ratio of the original or plate 2 is being determined;
One of the sensors 9 or a sensor 8 added in the measuring device 7 and calibrated by a calibration strip 64
The original or printing plate 2 has areas 4, 20, 46 with a minimum and/or maximum dot area that are scanned by A dispersion plate 15 and/or a polarizing filter 40 is provided in front of the arc tube 51 for uniformly illuminating a portion of a predetermined ink zone width on the printing plate. is arranged, and the sensor 9 detects the reflected light from each part of the zone width measurement area.
A device that calculates the dot area ratio of the original drawing or plate of a printing press. 11. The device according to claim 10, wherein the sensor 9 senses reflected light from individual parts of the area to be measured of zone width through a polarizing filter 58. 12. Claim 10 or 1, wherein the sensor 9 senses reflected light from individual parts of the zone width measurement area through the dispersion foil 39.
The device according to item 1. 13. Any one of claims 10 to 12, in which a safety roller 16 is provided to ensure that no damage to the original drawing or plate 2 can occur.
The equipment described in section. 14. A device for providing a calibration field on the plate, in which calibration field masks 57, 60 for copying the calibration field 4 onto the plate 2 are placed over the plate 2; equipment. 15. Apparatus according to claim 14, in which the calibration field mask 60 when using the negative copy 2 has a window through which this plate is illuminated in the corresponding position 59. 16. Apparatus according to claim 14, in which the calibration field mask 57 when utilizing a positive copy 2 has a closed surface, so that this plate is not illuminated in its place.