JPH0560424B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a remaining ink amount detection device for detecting the amount of ink remaining in a printing press.

(Conventional technology and its problems) In conventional printing machines that use photoelectric sensors to detect the amount of ink remaining, a light source emits light onto the ink surface, and the photoelectric sensor receives the reflected light from the ink surface. The ink level is converted into an electrical signal having a voltage value corresponding to the amount of ink, and the voltage value of this electrical signal is compared with a reference voltage value to determine the remaining amount of ink.

However, in this type of printing press, the amount of light reflected on the ink surface differs depending on the ink color, so even if the remaining amount of ink is the same, the output voltage value of the photoelectric sensor differs depending on the ink color, making it difficult to detect the remaining ink amount. This had the problem of variations in accuracy. In this case, it is possible to prevent variations in detection accuracy between ink colors by setting the reference voltage value individually according to the ink color, but in that case, it is necessary to set the reference voltage value every time the ink color changes. Furthermore, a problem arises in that the reference voltage value for each ink color must be measured in advance.

(Object of the Invention) This invention has been made to solve the above problems, and is capable of detecting the remaining amount of ink in a printing press easily and accurately without being affected by the ink color. The purpose is to provide equipment.

(Means for Achieving the Object) The ink remaining amount detection device for a printing press according to the present invention is a printing press equipped with an ink supply means that brings ink from an ink reservoir into direct contact with a roller and supplies ink to the surface of the roller. The remaining ink amount detection device includes: a light source that irradiates detection light with a fixed optical axis onto the surface of the rod-shaped ink portion that deforms into a rod shape and rotates as the roller rotates; and a light source that irradiates detection light with a fixed optical axis. a photoelectric sensor disposed at a position to receive the detected detection light; and an alternating current signal component caused by a change in the inclination of the ink surface with respect to the optical axis of the incident detection light among the output signal components of the photoelectric sensor. A signal that determines the remaining amount of ink based on a filter circuit to extract and a maximum range of change of the AC signal component extracted by the filter circuit, and notifies when the remaining amount of ink falls below a predetermined value. It is equipped with a discrimination circuit that outputs.

(Function) As the roller of the ink supply means rotates, the ink in the ink reservoir that comes into direct contact with the roller rotates.
Due to the viscosity of the ink itself and the effects of gravity, etc., the ink deforms into a rod shape and rotates while waving its surface, so that the inclination of the surface of the rod-shaped portion of the ink changes successively. As a result, when detection light with a fixed optical axis is projected toward the surface of the ink rod, the direction of reflection also changes, and the amount of light reflected in a predetermined direction changes. This change in light amount is detected by a photoelectric sensor, converted into an electrical signal, and output as an alternating current signal component.

A filter circuit removes noise and extracts the AC signal component.

Since the magnitude of the maximum variation width of this AC signal component depends on the remaining amount of ink, the determination circuit can determine the remaining ink amount based on the maximum variation width, and when the remaining ink amount is below a predetermined value. When it is determined that it is summer, it outputs a signal to that effect.

(Embodiment) FIG. 1 shows a schematic configuration diagram of a remaining ink amount detecting section in a printing press that is an embodiment of the present invention.

Ink 1 is stored between a doctor blade 2 which also serves as an ink fountain and an ink forming roller 3.
The doctor blade 2 has a cutting edge 2a along the surface of the ink form roller 3 at its lower tip, and when the ink form roller 3 rotates in the direction of the arrow during printing, a thin ink film corresponding to the pushing amount of the doctor blade 2 is formed. form.

The photoelectric sensor 4 is a reflective photoelectric sensor in which a light projecting part and a light receiving part are integrated, and projects light 5 onto the ink surface and receives the reflected light. The mounting position of this photoelectric sensor 4 is not particularly limited, but since the detection characteristics vary depending on the mounting position, mounting angle, and shape of the doctor blade 2, it is necessary to set it at a fixed position.

Next, the movement of the ink 1 will be explained.

While printing is stopped (that is, while the rotation of the ink forming roller 3 is stopped), the ink surface is maintained in a horizontal state, as indicated by reference numeral 1a in FIG. However, during printing (that is, while the ink form roller 3 is rotating), due to the viscosity of the ink 1, the ink 1 also rotates as the ink form roller 3 rotates, forming a rod-like shape. At this time, the ink surface fluctuates in a wave-like manner due to the influence of rotation. This phenomenon occurs in the same way regardless of the amount of ink 1, and the shape changes to a similar shape depending on the amount of ink. In FIG. 1, a rod-like shape when a large amount of ink 1 is used is illustrated with reference numeral 1b, and a rod-like shape when a small amount of ink 1 is used is illustrated with reference numeral 1c.

The photoelectric sensor 4 detects such a change in the state of the ink 1 as a change in the amount of reflected light, and converts it into an electrical signal.

FIG. 2 shows a block diagram of a circuit for converting the output signal of the photoelectric sensor 4 into a signal corresponding to a change in the amount of ink, that is, a remaining ink amount detection circuit. The light emitting circuit 6 shown in the figure allows the light emitting part 4a of the photoelectric sensor 6 to
is driven, and light is irradiated onto the ink surface. The light reflected on the ink surface is transmitted to the light receiving section 4 of the photoelectric sensor 4.
b and is converted into a voltage signal. The voltage is then amplified by the amplifier 7 to a required voltage level. The signal obtained here is a signal having a voltage value corresponding to the amount of ink, and includes an alternating current signal component based on fluctuations in the ink surface during printing.

FIG. 3 shows an example of a signal output from the amplifier 7. In the figure, the horizontal axis represents the amount of ink (shown by the diameter of the rotating rod), and the vertical axis represents the output voltage of the amplifier 7. Further, curve A in the figure shows a characteristic curve when the ink color is "red", and curve B shows a characteristic curve when the ink color is "black". All of them show characteristic curves during printing (illustration is omitted when stopped because there is no AC signal component based on fluctuations in the ink surface). As can be seen from both characteristic curves A and B, signal changes corresponding to the respective amounts of ink are obtained for both the ink colors "red" and "black", but the level difference is large. Therefore, when trying to detect the remaining amount of ink from the level of the output signal of the amplifier 7,
For example, when it is determined that there is no remaining amount of ink at 5φ, "1.9V" is used for red ink (characteristic curve A), and "0.7V" is used for black ink (characteristic curve B).
Therefore, it is necessary to set the judgment level according to the ink color.

However, if we focus on the AC signal component (the shaded area in Figure 3) based on the fluctuation of ink 1,
It can be seen that this AC signal component provides a signal change that corresponds to the amount of ink, regardless of the color of the ink. However, this signal is an AC signal of several Hz to several hundred Hz,
The waveform is random, and FIG. 3 shows its maximum range of variation.

In this way, the maximum variation width of the AC signal component is
What changes depending on the amount of ink remaining is that the ink, which deforms into a rod shape and rotates, rotates with its cross-sectional shape becoming completely circular due to the interaction between the ink's own viscosity and the gravity applied to it. This is because the surface of the ink rod-like part changes in a wavy manner because it changes periodically, and the angle of the ink surface (reflection surface) with respect to the light receiving part of the photoelectric sensor 4 changes sequentially. Then, the direction of reflection of the reflected light changes, which changes the amount of light received by the photoelectric sensor 4, and the detected voltage is output as an AC signal component, and the maximum change width of the AC signal component is determined by the diameter of the ink bar That is, it depends on the amount of ink remaining.

In other words, the larger the amount of ink remaining and the larger the cross-sectional diameter of the ink rod, the larger the radius of curvature of the surface of the ink rod, and the greater the amount of light when reflected toward the light receiving section of the photoelectric sensor 4. Due to the waving of the ink rod, the change in the amount of received light between when it is reflected toward the light receiving part and when it is not reflected becomes large.On the other hand, when the remaining amount of ink decreases and the diameter becomes smaller, the radius of curvature of the ink rod surface becomes smaller and the photoelectron The amount of light reflected toward the light receiving section of the sensor 4 decreases, and the difference between the maximum amount of received light and the minimum amount of received light becomes smaller.

As a result, as shown in Fig. 3, the smaller the remaining amount of ink, the smaller the maximum variation width of the AC signal component. This is caused by the relative change in the amount of light received due to the change in the direction of reflection caused by the change in the direction of reflection, and is not related to the absolute value of the amount of reflected light itself. It exhibits almost constant characteristics depending only on the amount.

Therefore, as shown in FIG. 2, the output signal of the amplifier 7 is passed through a filter circuit 8 to extract only the above-mentioned variation, that is, the alternating current signal component, and amplified by the amplifier 9 to a required voltage level. This signal
The rectifier circuit 10 rectifies the ink, and the peak hold circuit 11 holds the peak to obtain a level signal corresponding to the variation, that is, the amount of ink.

FIG. 4 shows an example of the output signal from the peak hold circuit 11. In the figure, the horizontal axis represents the ink amount, and the vertical axis represents the peak hold voltage. Further, curve C in the figure shows a characteristic curve when the ink color is "red", and curve D shows a characteristic curve when the ink color is "black". As can be seen from both characteristic curves C and D, signals of approximately the same level are obtained for both the ink colors "red" and "black", making it possible to detect the remaining amount of ink at a constant detection level. For example, if it is desired that there is no ink remaining when the ink amount is 5φ, the comparison circuit 12 created in the reference voltage generation circuit 13 (FIG. 2)
Just set the reference voltage to "1V". With this setting, the output voltage of the peak hold circuit 11 is compared with the reference voltage "1V" in the comparison circuit 12, and when the output voltage of the peak hold circuit 11 becomes "1V" or less, that is, the ink amount is 5φ.
When the amount of ink decreases below, the comparator circuit 11 outputs a signal to notify this fact, and the fact that the ink amount has decreased is notified by, for example, displaying on the display panel or sounding an alarm. As detected ink amount
If it is desired to set a value other than 5φ, a voltage value corresponding to the desired ink amount may be set as the reference voltage of the comparator circuit 12 in FIG.

In the above example, the ink colors are "red" and "black".
Although the above case has been described, since the ink surface changes in the same manner during printing for other ink colors, characteristic curves similar to characteristic curves C and D shown in FIG. 4 can be obtained. Therefore, it is possible to accurately detect the amount of ink regardless of the ink color, and there is no need to set a detection level (reference voltage) for each ink color.

In addition, since the amount of ink is detected using AC signal components based on fluctuations in the ink surface, even if the ink position changes slightly due to inking of the ink roller 3 on the plate cylinder (not shown), the detection accuracy will be affected. There will be little impact. For the same reason, the mounting accuracy of the photoelectric sensor 4 may be rough, and the setting becomes easy.

In the above embodiment, a direct current lighting system is used as the light emitting circuit 6 shown in FIG. Alternatively, a pulse lighting method may be adopted. In this case,
A detection circuit that extracts a frequency component corresponding to the pulse lighting frequency and an integration circuit that smoothes the signal are provided between the amplifier 7 and the filter circuit 8, and the signal is converted into a DC level signal and then input to the filter circuit 8. do.

In addition, in this example, since a photoelectric sensor with integrated light transmission and reception is used, it has the advantage that it is easy to install and does not take up much space. The principle is to detect changes in the amount of light reflected to the light-receiving part of the photoelectric sensor when the surface of the rod-shaped part of the ink that has been deformed into a rod-shape waves as the ink form roller rotates. It is sufficient that the light receiving part of the photoelectric sensor is placed within the range where the emitted light is reflected by the surface of the ink, and the light receiving part of the photoelectric sensor is not limited to an integrated light transmitting and receiving part. It may also be a separate photoelectric sensor.

Further, as is clear from the above-mentioned measurement principle of the present invention, the ink supply means is not limited to the doctor blade type ink supply device in the above-mentioned embodiments, but may also be used in which the ink in the ink reservoir is in direct contact with the roll. A known ink supply means that deforms the ink into a rod shape following the rotation of the roll may be used.

(Effects of the Invention) As described above, according to the ink remaining amount detection device for a printing press according to the present invention, as the roller of the ink supply means rotates, it deforms into a rod shape and rotates while waving its surface. By projecting detection light with a fixed optical axis onto the surface of the rod-shaped portion of the ink and receiving the reflected light with a photoelectric sensor, an AC signal component resulting from a change in the inclination of the ink surface is obtained. The maximum variation width of this AC signal component is
Since it depends on the size of the radius of curvature of the rod-shaped ink, that is, the remaining amount of ink, the remaining amount of ink can be detected based on the maximum range of change, and the discrimination circuit detects when the remaining amount of ink is below a predetermined value. Since it emits a signal when the ink runs out, it is possible to prevent the situation from running out of ink.

In addition, the rate of change of the maximum change width of the AC signal component is almost unaffected by the color of the ink and is determined only by the remaining amount of ink, so the remaining amount of ink can be easily and accurately determined for any color of ink. can be detected.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the remaining ink amount detection section which is an embodiment of the present invention, Fig. 2 is a block diagram of the ink remaining amount detection circuit, and Fig. 3 shows the relationship between the ink amount and the amplifier output voltage. FIG. 4 is a characteristic diagram showing the relationship between the amount of ink and the peak hold voltage. 1... Ink, 4... Photoelectric sensor, 6... Light emitter circuit, 8... Filter circuit, 10... Rectifier circuit,
11...Peak hold circuit, 12...Comparison circuit, 13...Reference voltage generation circuit.

Claims (1)

[Scope of Claims] 1. An ink remaining amount detection device for a printing press equipped with an ink supply means that directly contacts a roller with ink from an ink reservoir to supply ink to the surface of the roller, which detects the amount of ink remaining as the roller rotates. a light source that irradiates detection light with a fixed optical axis onto the surface of the ink bar that rotates while being deformed into a bar shape; and a photoelectric sensor disposed at a position to receive the detection light reflected on the ink surface. , a filter circuit for extracting an AC signal component resulting from a change in the inclination of the ink surface with respect to the optical axis of the incident detection light from among the output signal components of the photoelectric sensor; and an AC signal component extracted by the filter circuit. A determination circuit that determines the remaining amount of ink based on the maximum range of change of a signal component and outputs a signal to notify when the remaining ink amount falls below a predetermined value. Detection device.