JPS622201Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electrostatic non-contact yarn breakage detector that can detect yarn breakage without coming into contact with the yarn.

Conventionally, yarn breakage detectors have been used to detect yarn breakage by bringing a metal guide into contact with the traveling yarn and using the DC signal of the frictional charge generated on this guide (Japanese Utility Model Publication No. 14579/1979); There are known devices in which yarn is run through a capacitor to which a voltage is applied, and yarn breakage is detected using changes in the capacitance of this capacitor.

However, the former contact-type yarn breakage detector using frictional charge is based on the premise of contact friction between the yarn and the guide and DC signal detection based on the frictional charge, so it inevitably suffers from the following drawbacks. Ta.

(1) The DC signal to be detected is based on the friction coefficient of the guide.
The signal level and polarity vary greatly depending on various conditions such as the type of yarn, type of oil, yarn speed, and yarn tension, and the signal level and polarity are not constant. Therefore, yarn breakage can only be detected under certain conditions.

(2) As the thread comes into contact with the detection guide and is rubbed, the quality of the thread may be damaged.

(3) The yarn may wrap around the detection guide and damage it.

In addition, the latter type of yarn breakage detector based on changes in the capacitance of a capacitor requires applying voltage to the capacitor, and furthermore, it is technically difficult to detect changes in capacitance. Although yarn breakage in the case of fineness yarns can still be detected, there is a problem in that yarn breakages in high-speed running yarns or fineness yarns cannot be detected without a fairly large-scale device, which is not practical.

Furthermore, when directing an AC voltage signal to an amplifier with high input impedance, such as the detector described in JP-A-53-103039, the atmosphere in which the detector is installed contains a large amount of splattered oil, and the penetration of this splattered oil causes insulation resistance. In the silk-spinning process where a decrease in insulation resistance occurs, the generated induced voltage decreases significantly due to a decrease in insulation resistance, and detection can only be performed for several hours or days.

The purpose of the present invention is to overcome the drawbacks of the conventional yarn breakage detector as described above, and to
To provide a new electrostatic type yarn breakage detector capable of surely detecting yarn breakage with a simple and compact device, and furthermore, to provide a yarn breakage detector that can be sufficiently used in a silk reeling process.

To achieve this purpose, the electrostatic non-contact type yarn breakage detector of the present invention includes a shield case having an opening for passing the yarn, a detection electrode covered by the shield case, and a high input impedance. and a sensor having an impedance converter with low output impedance, the detection electrode facing the opening of the shield case and provided at a position not in contact with the yarn, and the shield case being grounded. First, the detection electrode and the shield case are connected via the impedance converter, and the potential of the detection electrode and the potential of the shield case are the same.

Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a detector of the present invention, FIG. 2 is a front view of a thread breakage detector according to an embodiment of the present invention, FIG. 3 is a plan view thereof, and FIG. 4 is a circuit diagram thereof.
Fig. 5 is a front view of a detector of the present invention according to another embodiment, Fig. 6 is a plan view thereof, and Fig. 7 shows the relationship between the insulation resistance (R') value and the output level between the detection electrode and the shield case. It is a graph showing a relationship.

As shown in FIG. 1, the yarn breakage detector of the present invention consists of a shield case 2 having an opening 1 through which the yarn Y passes, and a sensor 3 covered by the case 2. Sensor 3 is connected to opening 1
A detection electrode 4 is placed at a position facing the yarn Y and not in contact with the yarn Y.
It further has an impedance converter 5 with high input impedance and low output impedance.

Specifically, it is configured as shown in FIGS. 2 and 3, for example. That is, a metal inner case 6 (illustrated by a collection of dots) is placed on the side other than the opening 1 of a metal shield case 2 having an opening 1.
A sensor 3 covered with a cap is inserted and fixed with screws 7.

A printed circuit board 8 (shown with diagonal lines) is placed on the opening 1 side of the sensor 3 so as to cover the internal case 6.
A sensing electrode 4 made of a thin metal film is pasted on the side facing the opening 1, and a sensing electrode 4 made of a thin metal film is pasted on the opposite side (back side) of the sensing electrode 4, which has a high input impedance (approximately 20M).
Ω) An impedance converter 5 with a low output impedance (approximately 1Ω) is connected. A lead wire 9 is connected to it for supplying power and drawing output. In order to increase the mechanical strength and electrical reliability of the sensor 3, it is preferable to mold the inside of the inner case 6 with an insulating resin and integrate the sensor 3.

The circuit is as shown in Figure 4.

The detection electrode 4 is grounded via a resistor R1 (for example, 22 MΩ), and is also connected to the in-phase input terminal + of the IC operational amplifier 10 via a resistor R2.
Operational amplifier 1, which forms the main body of the impedance converter
0 are connected to form a "voltage follower" (a non-inverting amplifier with a gain of 1), and the resistor R
3, a voltage having the same phase and potential as the AC voltage induced in the detection electrode 4 is applied to the shield case 2 (not grounded). Capacitor C
1 and C2 are for preventing oscillation.

Assuming that the yarn Y is running at the position shown in the figure, electrostatic induction between the yarn Y and the sensing electrode 4 occurs due to a change in the potential of the yarn Y itself. An alternating voltage is induced. This AC voltage is outputted through an operational amplifier 10, and then amplified and converted into a DC signal, which is electrically connected to a yarn cutter (not shown) or the like.

If a thread breakage occurs, no alternating voltage is induced and the sensing signal therefore drops to zero level.
As a result, thread breakage is detected and the thread cutter is activated.

In the above embodiment, the operational amplifier 10 is one with high input impedance, low output impedance, and low noise as much as possible in order to not attenuate the induced AC voltage, improve the shielding effect, and increase the signal-to-noise ratio. It is preferable.

The shape of the shield case 2 is not limited to the above-mentioned embodiment, but can also be shaped as shown in FIGS. 5 and 6. In short, any shape may be used as long as it can improve the shielding effect and has an opening 1 for passing the yarn Y.

Although the sensor 3 can be fixed inside the shield case 2, it is preferable to provide it detachably as in the embodiment, since the surface of the detection electrode 4 can be cleaned. The present invention makes it easier to detect induced voltage by shielding the sensor including the detection electrode, and by not grounding the shield case and setting it at the same potential as the signal potential, even if the insulation resistance is low, the operational amplifier 1
The main feature is that the zero output level can be maintained at a high level.

FIG. 7 is a semi-logarithmic graph showing the relationship between the value of the insulation resistance R' and the output level of the operational amplifier 10.

In the figure, NE indicates the relationship when the shield case is not grounded as in the above embodiment, and E indicates the relationship when the shield case is grounded.

As can be seen from the figure, if the shield case is not grounded, the output level can be maintained between 0.9 and 1.0 if the value of R' is approximately 100 kΩ or more. On the other hand, when the shield case is grounded, the output level is low, and even when R' = 60MΩ, the output level is at most
I can only get an output level of 0.8.

Therefore, in order to maintain the output level between 0.9 and 1.0, it is necessary not to ground the shield case and to set it at the same potential as the signal potential.
The value of R' is preferably about 100 kΩ or more.

As explained above, the electrostatic non-contact yarn breakage detector of the present invention can exhibit the following effects.

This method detects the alternating current voltage induced by changes in the potential of the yarn Y itself, and has a circuit structure that can reliably detect the alternating current signal caused by this induced voltage. To reliably detect thread breakage with a compact and simple device without having to do anything. In other words, it is not affected by various conditions such as yarn type, yarn speed, yarn tension, etc., and it is not affected by conditions such as yarn type, yarn speed, yarn tension, etc., and it can also be used in an atmosphere where the resistance value inside the detector decreases due to the infiltration of splashed oil agents in the atmosphere. Even when used for thread breakage detection, thread breakage can be detected easily and reliably.

Since the threads are not abraded, the quality of the threads is not impaired.

Since there is no need for a detection guide that comes into contact with the yarn,
Of course, the threads do not wrap around each other, and the overall structure can be made compact and robust.

Since there is no need to hang the yarn on the detection guide,
Good workability.

Furthermore, in order to reliably detect the AC signal of the induced voltage, in addition to shielding the sensor, the present invention also uses a
Since voltages of the same potential are applied to the shield case via a low output impedance converter, the potential difference between the sensing electrode and the shield case is zero, and in principle, no leakage current flows between the sensing electrode and the shield case. do not have.

Therefore, even if the value of insulation resistance R' decreases, the output level can be maintained high without causing a drop in the induced AC voltage.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of the detector of the present invention, Fig. 2 is a front view, Fig. 3 is a plan view, Fig. 4 is a circuit diagram, and Fig. 5
The figures are a front view of another example, FIG. 6 is a plan view, and FIG. 7 is a graph showing the relationship between the value of insulation resistance R' and the output level. Code, 1: Opening, 2: Shield case, 3:
Sensor, 4: Sensing electrode, 5: Impedance converter.

Claims (1)

[Scope of utility model registration request] It consists of a shield case having an opening for passing the yarn, and a sensor covered by the shield case and having a sensing electrode and an impedance converter having high input impedance and low output impedance, and the sensing electrode is connected to the shield. The detection electrode and the shield case are connected via the impedance converter, and the shield case is not grounded and the sensing electrode and the shield case are connected through the impedance converter. An electrostatic non-contact yarn breakage detector, characterized in that the potential of the detection electrode and the potential of the shield case are the same.