JPH10278227A - Apparatus for monitoring thickness of ink film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To directly monitor a feed amount of ink by detecting a state amount related to an ink film thickness on an ink roller, operating an actually measured value of the ink film thickness from the state amount related to the ink film thickness, and generating an alarm when the actually measured value is outside a target value. SOLUTION: Before printing is started, data of a pattern area ratio of an ink film thickness on an ink roller 7 and target values of kinds of an ink, a paper, etc., are set in a data-processing apparatus 5. A detecting head 1 is moved and stopped by a scan means 2 at a predetermined position on the ink roller 7, and a state amount related to the ink film thickness is detected. The state amount related to the ink film thickness is input to an operating means 3 which in turns operates an actually measured value of the ink film thickness. After the whole range is detected completely, target values and actually measured values are displayed graphically at a display means of the data-processing apparatus 5. Then, the target values are compared with the actually measured values. When the actually measured value exceeds a range of the target value, an alarming means generates an alarm on the basis of an output of the data- processing apparatus 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention belongs to the technical field of offset printing. In particular, the present invention relates to an ink film thickness monitoring device for obtaining a desired print density by monitoring the thickness of an ink film on an ink roller in an offset printing press.

[0002]

2. Description of the Related Art In an offset printing machine, it is necessary to set an ink supply amount appropriately. When the supply amount of the ink is insufficient, the density in the printed matter is insufficient, and when the supply amount of the ink is excessive, the density is excessive in the printed matter. Further, in the case of multi-color printing, if the supply amounts of the respective color inks are not proper, the balance of the color tone in the printed matter is lost, and the desired color tone cannot be reproduced. If the supply amount of ink in the offset printing machine is before the start of printing,
Predicts the amount of ink used from the distribution of the printing plate size (determined by the printing press) and the pattern area ratio of the printing plate in the axial direction of the plate cylinder, and presets the opening of the ink adjustment key of the ink fountain according to the distribution Is done. After the start of printing, the ink supply amount is corrected based on the print reproduction in the printed matter. The evaluation of print reproduction is basically based on comparison with a proof print, and is performed by a visual check by an operator of the printing press and by measuring the print density of a predetermined portion (usually a density scale portion) of the print using a reflection densitometer.

[0003]

As described above, the supply amount of the ink is adjusted by the opening of the ink adjusting key of the ink fountain. The opening of the ink adjustment key is adjusted by the scale of the ink fountain in the case of manual operation, and adjusted by the scale displayed on the remote operation panel in the case of automatic operation. In order to achieve the adjustment by the scale as described above, it is a precondition that the opening degree of the ink adjustment key and the ink supply amount are uniquely determined and reproducibility is obtained. However, in practice, there is variation among a plurality of ink adjustment keys provided in the ink fountain, and there is aging due to mechanical wear and the like, and the precondition is not always satisfied. In addition, the state of the ink, especially the flow characteristics of the ink, varies depending on the environmental temperature, the production lot, and the handling. By adjusting the opening of the ink adjustment key to the scale of the ink fountain, it is possible to always obtain a constant ink supply amount. No.

Therefore, an object of the present invention is to adjust an inking device by adjusting the opening of an ink adjusting key or the like so that an adjusting operation for obtaining a desired printing density can be properly performed in an offset printing press. An object of the present invention is to provide an ink film thickness monitoring device for directly monitoring the resulting ink supply amount itself.

[0005]

The above objects are achieved by the present invention described below. That is, the present invention provides a detection head for detecting a state quantity related to an ink film thickness on an ink roller of an offset printing press, and an arithmetic unit for inputting the state quantity related to the ink film thickness and calculating an actually measured value of the ink film thickness. Setting means for setting a target value of the ink film thickness; display means for graphically displaying the actual measurement value and the target value; and alarm means for generating an alarm when the actual measurement value deviates from the target value. And an ink film thickness monitoring device having
It is. According to the present invention, a state quantity related to the ink film thickness on the ink roller of the offset printing press is detected by the detection head, and a state quantity related to the ink film thickness is input by the calculation means, and an actually measured value of the ink film thickness is calculated. The target value of the ink film thickness is set by the setting means, and an alarm is issued by the alarm means when the measured value deviates from the target value. Therefore, in order to be able to properly perform the adjustment work for obtaining the desired print density in the offset printing press, the ink supply amount itself as a result of adjusting the inking device by adjusting the opening degree of the ink adjustment key or the like. Can be monitored directly.

The present invention also provides that the state quantity relating to the ink film thickness includes an ink state quantity relating to light absorption by the ink itself of the ink film and a water state quantity relating to light absorption by moisture contained in the ink film. The calculating means calculates an actual measured value of the water content, and the setting means is an ink film thickness monitoring device for setting a target value of the water content. In offset printing, water is mixed into the ink by dampening water or the like, but according to the present invention, the water contained in the ink film together with the ink itself can be detected. Therefore, an alarm can be generated if the moisture content is abnormal. Also,
The measured value of the thickness of the ink film can be corrected by the moisture content, higher measurement accuracy can be obtained, and the ink supply amount can be monitored based on the measured value.

The present invention also provides a scanning means for moving the detection head in a direction parallel to the axis of the ink roller and stopping at a predetermined position, wherein the measured value is an ink film thickness in a direction parallel to the axis of the ink roller. And the target value is a target value of the distribution of the ink film thickness in the direction parallel to the axis of the ink roller. According to the present invention, the scanning unit moves the detection head in a direction parallel to the axis of the ink roller and stops at a predetermined position, so that it is possible to obtain an actually measured value of the distribution of the ink film thickness. The ink supply amount can be monitored as a distribution of the ink film thickness based on the measured value. The present invention is also an "ink film thickness monitoring device having a setting means for setting the target value at least by the type of ink, the type of paper, and the pattern area ratio". According to the present invention, since the target value is set based on at least the type of ink, the type of paper, and the pattern area ratio, more appropriate monitoring of the ink supply amount can be performed as compared with the case of the pattern area ratio alone or the like. it can.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to embodiments. FIG. 1 is a pictorial diagram showing the configuration of the ink film thickness monitoring device of the present invention. In FIG. 1, reference numeral 1 denotes a detection head for detecting a state quantity relating to an ink film thickness on an ink roller of an offset printing press; Numeral 3 denotes an arithmetic unit for inputting a state quantity relating to the ink film thickness to calculate an actual measured value of the ink film thickness. Reference numeral 4 denotes an input of the actual measured value of the ink film thickness to output to a data processing device and the like, and to operate the scanning unit 2. 5 is a data processing device such as a personal computer which also serves as setting means for setting a target value of the ink film thickness and display means for graphically displaying the target value and the measured value of the ink film thickness. The printing unit 7 of the offset printing press is an ink roller of an inking device of the printing unit.

FIG. 2 is a flow chart showing a process of monitoring the ink film thickness in the ink film thickness monitoring apparatus of the present invention. The operation of the ink film thickness monitoring device of the present invention will be described with reference to FIGS. First, in step S1, a target value of the ink film thickness on the ink roller 7 is set in the data processing device 5. The target value is the distribution of the ink film thickness in the direction parallel to the axis of the ink roller 7 based on the pattern area ratio data, the type of ink, the type of paper (fine paper, coated paper), the type of printing machine, the printing speed, the water content, and the like. Is determined so that an appropriate print reproduction can be obtained. Since the target value differs for each ink color, different settings are made for each inking unit. The setting of the target value is usually performed before the start of printing.

Next, in step S2, the scanning means 2 is operated to measure the ink film thickness at a predetermined position on the ink roller 7, and the detection head 1 is moved in a direction parallel to the axis of the ink roller 7 and stopped at the predetermined position. I do. Next, step S3
, The detection head 1 detects a state quantity related to the ink film thickness. The state quantity includes an ink state quantity relating to light absorption by the ink itself of the ink film and a water state quantity relating to light absorption by moisture contained in the ink film. The detection of the state quantity related to the ink film thickness is usually performed after the start of printing. For example, a constant printing speed (for example, 700 rpm
After a certain period of time e), the measurement is started.

Next, in step S4, the calculating means 3
Calculates the actual measured value of the ink film thickness by inputting the state quantity relating to the ink film thickness. Here, an actually measured value of the ink film thickness at a predetermined position (one of a plurality of predetermined positions) is obtained. Since the actually measured value to be obtained is the distribution of the ink film thickness in the direction parallel to the axis of the ink roller 7, it is next determined in step S5 whether the detection of the entire range (all the predetermined positions) has been completed. If the detection of the entire range is not completed, the process returns to step S2, and the following steps are repeated at the next predetermined position. When the detection of the entire range is completed, the process proceeds to step S6.

In step S6, the data processing device 5
The target value and the actually measured value are graphically displayed on the display means. If not only the target value and the actually measured value but also the opening of each ink adjustment key of the ink fountain, the rotation speed of the ink discharge roller, and the printing speed are displayed at the same time, the situation can be grasped more accurately. Next, in step S7, the data processing device 5
In, it is determined whether the measured value is within the range of the target value by comparing the target value with the measured value. If the measured value is within the range of the target value, the process proceeds to step S10. If the measured value is out of the range of the target value, the warning means generates an alarm based on the output of the data processing device 5 in step S8. The alarm is given not only by a buzzer or sound, but also by blinking or changing the display color of the graphical display corresponding to the ink adjustment key whose measured value is out of the target value range on the display means of the data processing device 5. it can.

Next, in step S9, the operator of the printing press corrects the setting of the opening of the ink adjustment key of the inking unit. Correction of the opening setting of the ink adjustment key is usually
This is performed on the remote operation panel of the inking device that also serves as a color stand for printed matter. In that case, the remote operation panel and the data processing device 5 are arranged adjacent to each other,
The operator of the printing press corrects the setting of the opening of the ink adjustment key while monitoring data such as target values and actual measurement values graphically displayed on the display means of the data processing device 5.

Next, in step S10, it is determined whether or not to continue the process of monitoring the ink film thickness. If the process is to be continued, the process returns to step S2 and the following steps are repeated. If not continued, the process is terminated. The above is the basic process of the process in the ink film thickness monitoring device of the present invention. Through this process, the ink film thickness on the ink roller 7 is adjusted so as to coincide with the target value. Since the target value is set so as to obtain an appropriate print reproduction, an appropriate print reproduction can be obtained by the ink film thickness monitoring device of the present invention.

Next, a method of setting the target value will be described. As described above, the target values are the pattern area ratio data, the type of ink, the type of paper (fine paper, coated paper), the type of printing machine,
The printing speed, the water content, and the like are determined so that an appropriate print reproduction can be obtained as the distribution of the ink film thickness in the direction parallel to the axis of the ink roller 7. In practice, a target ink film thickness is determined and set for each position of the ink fountain corresponding to each ink adjustment key. The method for obtaining the ink film thickness is determined by substituting the corresponding numerical value in the following equation (1).

Tk = C * Sk * i * p * t * f (v) * g (w) where Tk: ink film thickness corresponding to the kth ink adjustment key C; coefficient Sk; kth ink Pattern area ratio i corresponding to adjustment key i; Constant determined by ink type (color, brand) p; Constant determined by paper type t; Constant determined by printing machine type f (v); Correction function determined by printing speed v Value of f g (w); Value of correction function g determined by water content w

FIG. 3 is an arrangement diagram of the detection head and the scanning means in the ink film thickness monitoring device of the present invention. FIG. 3A is a front view, and FIG. 3B is a top view. 3, the same parts as those of FIG. 1 are denoted by the same reference numerals. In FIG. 3, 8a and 8b are frames of the printing unit, 9a and 9b.
Is a bracket for attaching the scanning means 2 to the frames 8a and 8b, 10 is a guide rail for guiding the movement of a stage supporting the detection head 1, and 11 is a power supply line or a signal line of the detection head 1 when scanning. This is a wiring guide for preventing interference with the wiring.

As shown in FIG. 3, the detection head 1 is provided on a stage (not shown) supported by a guide rail 10 so as to be movable in a direction parallel to the axis of the ink roller 7. The stage is moved by a timing belt (toothed belt) driven by a pulse motor and a motor controller or the like, and can be stopped at a predetermined position. Further, the sensor measurement point is placed on the peripheral surface of the ink roller 7 so that the direction of the measurement axis of the detection head 1 is directed to the center axis of the ink roller 7.

Next, the operation of measuring the ink film thickness on the ink roller 7 will be described. The series of operations are programmed in the control means 4. In FIG. 1, the control means 4
Is a diagram of a control box, and the control means 4 is composed of a programmable sequencer or the like housed therein. The control means 4 operates a drive motor (not shown) in response to an input for instructing the start of a measurement operation by an operator or the like, and moves a moving stage (not shown) so that the detection head 1 on the moving stage moves the ink roller. 7. The ink film thickness at a predetermined position on 7 can be measured. The predetermined position is usually a position corresponding to each of a plurality of ink adjustment keys provided on an ink fountain (not shown). If the ink adjustment key is No. 1 to No. If there are up to 32,
Initially, the detection head 1 is no. It moves to a position on the ink roller 7 corresponding to one ink adjustment key and measures the ink film thickness there.

The measurement of the ink film thickness is performed a plurality of times during a predetermined time, and a measured value is obtained as an average value. During that time, the detection head 1 is stopped, but the ink roller 7 is rotating, and measurement is performed at a plurality of points around the peripheral surface of the ink roller 7, and the measured value as the average value is obtained. . The calculation of the measured value is performed by the calculating means 3
It is performed in. The calculating means 3 A / D converts an output signal of the detection head 1 which is a state quantity relating to the ink film thickness into digital data, processes the data, and calculates the ink film thickness. As the arithmetic means 3, a device capable of performing data processing, such as a dedicated microcomputer, a programmable sequence controller, or a personal computer, is used.

No. When the measurement of the ink film thickness at the position on the ink roller 7 corresponding to the first ink adjustment key is completed,
Next, the detection head 1 is no. It moves to a position on the ink roller 7 corresponding to the second ink adjustment key, and measures the ink film thickness there. By repeating such a measurement operation, 1
-No. When the measurement of the ink film thickness at the position on the ink roller 7 corresponding to the ink adjustment key of No. 32 is completed, the measuring head 1 then moves to No. 32. Return to the position on the ink roller 7 corresponding to the one ink adjustment key, and measure the ink film thickness there again. Unless the operator or the like inputs an instruction to stop the measurement operation, the control means 4 repeats such a measurement operation.

On the other hand, the N obtained by the above measuring operation
o. 1 to No. Measurement data (actual measurement value) of the ink film thickness at the position on the ink roller 7 corresponding to the 32 ink adjustment keys
Is converted into graphical data such as a bar graph of the ink film thickness on the vertical axis and the number of the ink adjustment key on the horizontal axis in the data processing device, and output to a display or the like. In addition to the measured data (actually measured values), desired data (target values) are also converted into graphical data such as a bar graph of ink film thickness and the number of ink adjustment keys on the horizontal axis, and output to a display or the like. . This facilitates comparison between the two, and allows the operator to accurately grasp the state of the ink film pressure.

Next, a detection head which can be used in the ink film thickness monitoring device of the present invention will be described. As a method of the detection head that detects the ink film thickness on the ink roller, a method using a combination of an electric capacity type sensor whose detection value changes according to the ink film thickness and an eddy current type sensor whose detection value does not change according to the ink film thickness is used. is there. There is also a method of using a combination of light having a wavelength whose detection value changes with the ink film thickness and light having a wavelength whose detection value does not change with the ink film thickness. The former requires that the ink roller be a conductor. Since the basic concept of deriving the ink film thickness from the two characteristic detection values is the same, only the latter method will be described here.

One example of the method of the detection head 1 for detecting the ink film thickness on the ink roller is a method of detecting the amount of reflected light (reflectance) for light of at least two different wavelengths. One of the two wavelengths is light having a wavelength partially absorbed by the ink film and reflected on the ink roller surface, and the other is light having a wavelength not absorbed by the ink film and reflected on the ink roller surface. When the two wavelengths are two wavelengths of light that have passed through two filters that transmit a specific wavelength from one white light source, the two wavelengths are used to determine the two different wavelengths of light. In the case of light of two wavelengths generated by the emitting luminous body, the ink film thickness can be derived from the reflectance ratio based on a conversion table or the like.

For example, the reflected light amount of light of two wavelengths passing through two filters transmitting a specific wavelength from one white light source is represented by Vs (reflected light amount of wavelength partially absorbed by the ink film; output of measurement light), Vc (reflected light quantity of a wavelength not absorbed by the ink film; reference light output). First, the absorbance X is calculated according to the following equation (2).

X = log (Vc / Vs)

At this time, there is the following equation 3 between the absorbance X and the ink film thickness Y.

Y = a + b * X Therefore, by determining a and b in advance by experiments, or by determining a conversion table describing the relationship between X and Y, the ink film thickness can be reduced. You can ask.

Also, when detecting the amount of water contained in the ink film, the same method as described above can be applied. One of the two wavelengths is light of a wavelength partially absorbed by the water contained in the ink film and reflected on the surface of the ink roller, and the other is not absorbed by the water contained in the ink film and reflected on the surface of the ink roller. Light of a given wavelength. For example, typical infrared absorption bands of ink have wavelengths of 3.4 μm, 5.74 μm, and 6.85 μm, and typical infrared absorption bands of water have a wavelength of 2.96.
μm, 4.80 μm, and 6.10 μm.

Next, an example of a method for obtaining an actually measured value of the ink film thickness corrected by the measured amount of water will be described.
The ink film thickness Y is obtained from the above equation (2). The ink film thickness Y is not corrected by the measured amount of water. For correction, an actual measurement value of the corrected ink film thickness can be obtained by determining a correction table in which a correction value based on the amount of moisture is described. Table 1 shows an example of the correction table. The values not in the correction table can be obtained by applying a well-known interpolation method.

[Table 1]

[0028]

As described above, according to the present invention, in order to make it possible to properly carry out adjustment work for obtaining a desired print density in an offset printing press, the opening degree of an ink adjustment key is adjusted. The ink supply itself as a result of adjusting the inking unit can be directly monitored. The state quantity related to the ink film thickness includes the ink state quantity related to light absorption by the ink itself of the ink film and the water state quantity related to light absorption by moisture contained in the ink film. According to the present invention in which the setting unit sets the target value of the water content, it is possible to detect the water contained in the ink film together with the ink itself of the ink film. Therefore, an alarm can be generated if the moisture content is abnormal. Further, the measured value of the thickness of the ink film can be corrected based on the water content, higher measurement accuracy can be obtained, and the ink supply amount can be monitored based on the measured value. In addition, there is a scanning unit that moves the detection head in a direction parallel to the axis of the ink roller and stops at a predetermined position, and the measured value is the measured value of the distribution of the ink film thickness in the direction parallel to the axis of the ink roller. According to the present invention, the value is the target value of the distribution of the ink film thickness in the direction parallel to the axis of the ink roller, the measured value of the distribution of the ink film thickness can be obtained, and the ink supply amount can be determined based on the measured value. The distribution of the ink film thickness can be monitored. Further, according to the present invention having the setting means for setting the target value by at least the type of ink, the type of paper, and the pattern area ratio, the target value is set based on at least the type of ink, the type of paper, and the pattern area ratio. Therefore, it is possible to more appropriately monitor the ink supply amount.

[Brief description of the drawings]

FIG. 1 is a pictorial diagram showing a configuration of an ink film thickness monitoring device of the present invention.

FIG. 2 is a flowchart showing a process of monitoring the ink film thickness in the ink film thickness monitoring device of the present invention.

FIG. 3 is an arrangement diagram of a detection head and a scanning unit in the ink film thickness monitoring device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Detection head 2 Scanning means 3 Computing means 4 Control means 5 Data processing device 6 Printing unit 7 Ink roller 8a, 8b Frame 9a, 9b Bracket 10 Guide rail 11 Wiring guide

Claims (4)

[Claims] 1. A detecting head for detecting a state quantity related to an ink film thickness on an ink roller of an offset printing press; an arithmetic means for inputting the state quantity related to the ink film thickness to calculate an actual measured value of the ink film thickness; Setting means for setting a target value of the ink film thickness; display means for graphically displaying the measured value and the target value; and warning means for generating a warning when the measured value deviates from the target value. An ink film thickness monitoring device, comprising: 2. The state quantity relating to the ink film thickness includes an ink state quantity relating to light absorption by the ink itself of the ink film and a water state quantity relating to light absorption by moisture contained in the ink film. Calculate the actual measured value of moisture content,
2. The ink film thickness monitoring device according to claim 1, wherein the setting unit sets a target value of the water content. 3. Scanning means for moving the detection head in a direction parallel to the axis of the ink roller and stopping at a predetermined position, wherein the measured value is a distribution of an ink film thickness in a direction parallel to the axis of the ink roller. The ink film thickness monitoring device according to claim 1 or 2, wherein the target value is an actual measurement value, and the target value is a target value of a distribution of the ink film thickness in a direction parallel to an axis of the ink roller. 4. An ink film thickness monitoring apparatus according to claim 1, further comprising setting means for setting said target value based on at least a kind of ink, a kind of paper, and a pattern area ratio.