JPS62244640A - Apparatus for detecting residual amount of ink in printing press - Google Patents

Abstract

PURPOSE:To provide the ink residual amount detection apparatus of a printing press capable of easily detecting the residual amount of ink with good accuracy, by mounting a discrimination circuit for discriminating the residual amount of ink on the basis of the output signal of a filter circuit and outputting a signal when the residual amount of the ink reaches a predetermined value or less. CONSTITUTION:The light emitting part 4a of a photoelectric sensor is driven to irradiate the surface of ink with light and the reflected light is incident to the light receiving part 4b of said photoelectric sensor to be converted to a voltage signal which is, in turn, amplified by an amplifier 7. The output signal of the amplifier 7 is passed through a filter circuit 8 to extract only a variation component which is, in turn, amplified to a necessary voltage level by an amplifier 9 to be rectified by a rectifier circuit 10 while the peak value thereof is held by a peak holding circuit 11 to obtain a variation component, that is, the level signal corresponding to the amount of ink. The output voltage of the peak holding circuit 11 is compared with reference voltage by a comparing circuit 12 and, when the output voltage of the peak holding circuit 11 reaches the reference voltage or less, a signal is outputted from the comparing circuit 11 and the reduction in the amount of ink is displayed on a display board or informed by alarm sound.

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 irradiates the main surface of the ink, and the photoelectric sensor receives light reflected from the ink surface. Then, six voltage values corresponding to the ink level are converted into electrical signals, and the voltage values of the electrical signals are compared with a reference voltage of 1 to determine the remaining amount of ink.

However, in this type of printing press, the reflection peaks on the ink surface differ depending on the ink color, so even if the remaining amount of ink is the same, the output voltage value of the photoelectric sensor 1J differs depending on the ink color, and the remaining ink m The problem was that the detection accuracy varied. In this case, if the fall pressure value is set individually according to the ink color, variations in detection accuracy between ink colors can be prevented, but in that case,
Problems arise in that the reference voltage value must be set each time the ink color changes, and the base Q-voltage value for each ink color must be measured in advance.

(Object of the Invention) The present invention has been made to solve the above-mentioned problems, and is capable of easily detecting ink residue m in a printing press without being affected by ink color. Detection Hf
The purpose is to provide fi.

(Means for Achieving the Object) In order to achieve the above object, the ink remaining amount detection device in the printing press of the present invention includes a light source that irradiates light onto the ink surface and a light source that receives reflected light from the ink surface. a photoelectric sensor that converts into an electrical signal according to the amount of ink remaining; a filter circuit that extracts an alternating current signal component caused by fluctuations in the ink surface from among the output signal components of the photoelectric sensor; The apparatus includes a determination circuit that determines the remaining amount of ink and outputs a signal notifying the user when the remaining amount of ink becomes less than a predetermined value.

(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.

The ink 1 has a doctor blade 2 which also serves as an ink fountain.
Ink deposits are collected between the rows 53.

Doctor blade 2 has 421 IJO- at its lower tip.
The blade 2a is provided with a cutting edge 2a along the surface of the doctor blade 2, and during printing, ink is deposited as the roller 3 rotates in the direction of the arrow (1), thereby forming a thin ink film corresponding to the push-in gate of the doctor blade 2.

The photoelectric sensor 4 is a reflection type 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 (2) of this photoelectric sensor 4 is not particularly limited, but since the detection characteristics change 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, the ink is deposited while the rotation of the 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 WG propeller 3 is rotating), due to the viscosity of the ink 1, the ink 1 also rotates as the roller 3 rotates, resulting in 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, the rod-like shape when there are many piles of ink 1 is illustrated with reference numeral 1b, and the rod-like shape when there is a small amount of ink 1 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 charging sensor 4 into a signal corresponding to a change in the amount of ink, that is, a circuit for detecting remaining ink m. By the light projecting circuit 6 shown in the figure,
The light emitting als4a of the photoelectric sensor 4 is driven to irradiate the ink surface with light. The light reflected on the ink surface enters the light receiving section 4b of the photoelectric sensor 4 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 on the surface of the ink 1 during printing.

As the third factor, an example of a signal output from the amplifier WA7 is shown.

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 amplification 37. Also,
Curve A in the figure shows a characteristic curve when the ink color is "red", and curve IQB 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 songs 11A and B, both the ink colors "red" and "black" have their respective in'1-ffi
Although a signal change corresponding to the current level can be obtained, the level difference is large. Therefore, when trying to detect the remaining ink m from the level of the output signal of the amplifier 7, for example, when determining that there is no cruelty with a certain amount of ink, for example, 5φ, Celtic red ink (characteristic surface 1!ilA> 17) I go r 1.9VJ
In the case of , black ink (characteristics $18), the level is different from ro, 7VJ, and it is necessary to set the determination level according to the ink color.

However, if we pay attention to the alternating current signal component (the shaded area in FIG. 3) based on the fluctuation of ink 1, we can see that this alternating current signal component produces a signal change according to the ink output regardless of the ink color. However, this signal ranges from several Hz to several hundred H.
2, the waveform is random, and FIG. 3 shows its maximum change. The reason why there is little difference in the amount of variation depending on the ink color is considered to be because the change in total reflected light on the ink surface due to the variation is detected.

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 is rectified by the rectifier circuit 10,
A peak hold circuit 11 holds the peak to obtain a level signal corresponding to the variation, that is, between inks.

FIG. 4 shows an example of the output signal from the peak hold circuit 11. In the figure, the horizontal axis represents the ink gap, and the vertical axis represents the peak hold voltage. Also, curve C in the figure has an ink color of "
The curved line shows the 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 ink colors "red" and "black" and b, making it possible to detect the remaining amount of ink at a constant detection level. For example, if you want to make the ink color 5φ and there is no ink remaining, then
The reference voltage of the comparator circuit 12 created in Fig.
Just set it to vJ. With this setting, the comparator circuit 12 compares the output voltage of the peak hold circuit 11 with the reference voltage "1v", and when the output voltage of the peak hold circuit 11 becomes "1VJ or less, that is, the ink amount is less than 5φ". When this happens, a signal is output from the comparator circuit 11 to notify this fact, and the fact that the in F[ has become low is notified by, for example, displaying on the display panel, sounding an alarm, etc. Detected in F= If you want to set a value other than 5φ as 1, you can set the voltage value corresponding to the desired ink 1 as the reference voltage of the comparator circuit 12 in FIG.

In the above example, the case where the ink colors were "red" and "black" was explained, but since the ink surface changes in the same way during printing for other ink colors, the fourth
Characteristic curves similar to characteristic curves C and D shown in the figure are 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 projecting circuit 6 shown in FIG. 2, but the photoelectric sensor 4
In order to extend the light receiving distance and improve noise resistance, a pulse lighting system may be adopted as the light projecting circuit 6. In this case, between the amplifier 7 and the filter circuit 8,
A detection circuit that extracts a frequency component corresponding to the pulse lighting frequency and an integration circuit that smoothes the signal are provided, and the signal is converted into a DC level signal and then input to the filter circuit 8.

(Effects of the Invention) As described above, according to the remaining ink amount detection device in the printing press of the present invention, the amount of remaining ink is detected by detecting fluctuations in the ink surface during printing. The effect is that the residual ink m can be detected easily and accurately without being affected by the ink color.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of a remaining ink amount detection section which is an embodiment of the present invention, Fig. 2 is a block diagram of a remaining ink amount detection circuit, and Fig. 3 is a characteristic showing the relationship with the output voltage of the 1μ amplifier. 4 are characteristic diagrams showing the relationship between ink products and peak hold 1 pressure.

Claims (1)

[Claims] (1) A remaining ink amount detection device that detects the amount of ink remaining in a printing press, which includes a light source that irradiates light onto the ink surface, and receives reflected light from the ink surface to generate an electrical signal according to the amount of remaining ink. a photoelectric sensor for converting; a filter circuit for extracting an alternating current signal component caused by fluctuations in the ink surface from among the output signal components of the photoelectric sensor; and a filter circuit for determining the amount of ink remaining based on the output signal of the filter circuit, A remaining ink amount detection device for a printing press, comprising a determination circuit that outputs a signal to notify when the amount falls below a predetermined value.