JPS61172077A - Multiple magnetic detection switch - Google Patents

Abstract

PURPOSE:To obtain a magnetic detection switch having high sensitivity, a high response speed and simple circuit constitution, by arranging a large number of saturable coils changed in inductance by magnetism in a line. CONSTITUTION:A large number of saturable coils L1-Ln changed in inductance by magnetism are arranged in a line and voltage is applied to the saturable coils L1-Ln from a high frequency oscillator OSC through a series resistor R3. Each of the saturable coils L1-Ln is constituted by appling winding an I-shaped Permalloy core and the magnetic detection sensitivity thereof is changed by the thickness or shape of the core. Further, detection switch circuits D1-Dn turned ON/OFF upon the detection of the change in inductance are provided to the saturable coils L1-Ln and the output terminals of adjacent detection switch circuits are mutually connected by output resistors R1-Rn-1 (including one with a resistance value of 0). A constant current is supplied to the output resistor groups R1-Rn-1 connected in series and DC voltage corresponding to the position of a magnetic body 10 is taken out from the output resistor groups R1-Rn-1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multiplex magnetic sensing switch using a number of saturable coils arranged in a row.

[Problems with conventional technology]

There have been devices in the past in which a number of magnetically sensitive proximity switches are arranged in the form of a scale or potentiometer.

The first example is one in which a group of resistors is connected by connecting a large number of reed switches linearly. A magnet is attached to a coaxially moving float, and the position of the magnet is detected by the operation of the reed switch. Water level gauges using this method have been in use for some time. However, since this device uses contacts for the switches, it is not a non-contact system and uses many switches, which has problems with its lifespan.In addition, the reed switch requires a magnetic field of 100 or more causes, which requires a large separation between the magnet and the switch. It is not used for anything other than water level gauges.

The second example is one in which a number of saturable cores are arranged in a line as sensors, and although the shape is the same, the number of sensors is switched by an electronic circuit and the output is output, so it is called a scanning type. Although this device provides output in the form of a digital display, there are problems in that the response speed is slow due to scanning and the scanning circuit is complicated (see Japanese Patent Publication No. 34883/1983).

Therefore, the present invention detects the position of a moving magnet, such as a magnet attached to a moving body, in a non-contact manner, has high sensitivity that operates even in a weak magnetic field of about 10 Gauss, and has a large distance from the magnet. The object of the present invention is to provide a magnetic detection switch which has a simple circuit configuration and a fast response speed.

[Means for solving problems]

In order to achieve the above object, the present invention arranges in a row a large number of saturable coils whose inductance changes due to magnetism, and supplies voltage to each of these saturable coils from a high frequency oscillator via a series resistor. Each saturable coil is provided with a detection switch circuit that turns on and off by detecting changes in inductance, and the output terminals of adjacent detection switch circuits are connected to each other with an output resistor, and the output resistors connected in series are connected to each other. A constant current was supplied, and a DC voltage corresponding to the position of the magnet was output from this resistor group.

[Effect]

When a magnetizing body approaches one of the saturable coils arranged in a row, the core becomes saturated and the coil terminal voltage decreases, and the detection switch circuit of that saturable coil is turned on, and the series connected with a constant current is turned on. A DC voltage corresponding to the position of the magnet generating body is generated across the series output resistor from the right or left end of the output resistor group to the connection point of the output resistor corresponding to the position of the magnet generating body.

〔Example〕

FIG. 1 is a circuit diagram showing a basic embodiment of the present invention.

In the same figure, Ll +L2- ''・, LllI are saturable coils that serve as magnetic sensors, and are I-type nog malloy coils.
The magnetic detection sensitivity changes depending on the thickness and shape of the core, which is wound with wire. In this example, the height is 5 mm, the width is 4 mm,
A permalloy core with a thickness of 0.05 mm and a wire wound 200 times was used. OSC is a high frequency (e.g. about 400
kHz) oscillator, R8 is a series resistor (e.g. [3Ω]),
D, to Dn are detection switch circuits, R1-Rn are output resistors, CT is a constant current circuit, S is a changeover switch, and M is a magnetizing body.

FIG. 4 shows the characteristics of a saturable coil. When the magnetic field H applied to the core increases, the core becomes saturated and the coil terminal voltage decreases. The detection switch circuit ~Dn is the magnetic field value H
, is configured to turn on and off at the boundary of . In this example coil, H- is approximately 15 Gauss. To further increase the sensitivity of the coil and operate it with a low magnetic field, add a bias magnetic field H3 using a permanent magnet, and Ha-Hm-H
It can be turned on and off with a magnetic field as low as 1. The saturable coils L1 to Ln are arranged at regular intervals, for example, every 10 mm, and the values of the output resistances R1 to R,1 are set equal to Ro
If so, a stepped DC output voltage corresponding to the position of the magnet M is obtained. Now, assuming that the changeover switch S is in the position shown in the figure and the magnetizing element M is in the position shown in the figure, the terminal voltage of the saturable coil L3 is υ when the lower stage transistor is turned off, and the rear stage transistor of the detection switch circuit D3 is turned on. becomes. Therefore,
The connection point between the output resistors R2, R and the power supply (-) line is electrically connected, and between the power supply (-) line and the output terminal (R3+R4+...
・+R, -2)I. A voltage is generated. However, Io is a constant current.

When the selector switch S is switched to the upper side, the output voltage becomes (R1
+R2) becomes IO. That is, the output voltage indicates the distance from the left end position to the magnetic body M when the changeover switch S is on the upper side, and the distance from the right end position to the magnetic body M when the changeover switch S is on the lower side. Figure 2 shows an example of the relationship between the position of the magnetizing element M and the output voltage when the output resistance is set to a constant value R0.
is for detecting the right side of the lower magnetic body, making it suitable for detecting the right end of the magnetic body. In the case of left-side detection, the output voltage has the same shape as in FIG. 2, with the upper right being in the form of a step.

Although FIG. 2 shows a case in which the coil spacing and output resistance value are constant, FIG. 3 shows a modified example in which the coil spacing is finer at the center and coarser at the ends.

In FIG. 3, the output resistance value R0 is also set to 0 at both ends. In this way, the shape of the stepped voltage can be changed, so it can be designed to have a desired shape depending on the application.

Next, applications suitable for the present invention will be described.

FIG. 5 is a plan view showing an example in which the present invention is used for trajectory control of an unmanned vehicle. This figure shows a case where a rubber magnet belt with a width of 20 mm and a thickness of 2 mm is embedded or pasted on the floor surface, and the movement of an unmanned vehicle is controlled along this magnetic belt.

Although the unmanned vehicle includes a single drive unit and a control unit, the figure only shows a multiple detection switch for detecting the track position. This multiple detection switch (hereinafter abbreviated as "detection switch") has the configuration and operation as described above.

If such a detection switch is used, it will operate even if the distance between the rubber magnet and the detection switch is increased to 20 mm. Therefore, the detection switch is mounted at a distance of, for example, about 10 mm from the floor, and is mounted elastically so that it will spring up if there is a protrusion of 10 mm or more on the floor.

The detection switch used to control this unmanned vehicle produces an output voltage as shown in Figure 3.
In the range 301, saturable coils are arranged at 5 mm intervals, and in the outer 80 mm range, saturable coils are arranged at 20 mm intervals so that the output voltage is constant. In this way, the output characteristics are divided into three parts. The position of the car is controlled by the sensor control in the range of ±30mm in the center, and the output voltage is constant in the range of 80mm outside of that, so surge control is not possible. This is a warning signal that indicates a deviation to the left or right within a millimeter range. If it is outside the range of ±110 mm of the detection switch, the output voltage will not exceed a predetermined value (for example, SV) (see Figure 3), and if this voltage is detected, an abnormality or an abnormality exceeding the limit that the car can control will be detected. The vehicle will be stopped as an accident.

In this way, the detection switch plays a three-way role. Since the route of the unmanned vehicle has branching as shown in FIG. 5, it is preferable that the detection switch can easily control the branching. As described above, the detection switch shown in FIG. 1 can select whether to detect the right end or the left end of the magnet by using the changeover switch S. In the case of FIG. 5, if the right end of the magnetic body is detected, the vehicle can be driven straight regardless of the branch point. If the selector switch is set to detect the left end, a signal to proceed to the left branch course can be generated. Therefore, by using the detection switch of the present invention, branching control is extremely easy. The electronic circuit connected to the output side of the detection switch to take out signals such as control, warning, stop, etc. will not be specifically explained because it is easy for those skilled in the art to design it. FIG. 3 is a plan view showing an example of use in stop position control. Place an unmanned vehicle in a certain location (position)
In order to stop the motor accurately using electrical control, for example, it is necessary to issue a deceleration signal before the fixed point, decelerate the motor, and stop the motor near the fixed point. Positioning by control. That is, the brake is applied slightly before the fixed point to stop the vehicle at the fixed point.

In such a case, it is necessary to confirm whether the stop position is at a fixed point, and a simple limit switch is not sufficient, but the detection switch of the present invention can also be used for such stop control. That is, as shown in FIG. 6, a stop control detection switch is attached to the side of the vehicle parallel to the direction of travel, in addition to the course detection switch as shown in FIG. Bury a stop point magnet (rubber magnet) on the floor at a position that indicates the stop point corresponding to the stop control detection switch. If this magnet is 20 mm wide, 60 mm long, and 4 mm thick, a detection switch with the characteristics shown in Figure 3 will operate even if the magnet and switch are separated by 30 mm. 〇As in the example shown in Fig. 3, a sensor that produces a step-like output voltage with a linear slope in the range of ±30 mm from the center and a constant output voltage in the range of ±80 mm outside the center, has a stop point of 110 mm. A deceleration signal can be sent from the front, and the sir can start controlling the vehicle from 30 millimeters ahead.

Therefore, the multiple detection switch of the present invention also becomes a sensor suitable for stop position control. Furthermore, as a stop position control sensor, it can be widely used not only for unmanned vehicles but also for stand cranes, elevators, and other moving objects.

〔Effect of the invention〕

As explained above, according to the present invention, the following various remarkable effects can be obtained.

B) Since the position of the moving magnet can be detected without contact,
-Can be used for general purposes as a scale for foxgloves.

←) If a saturable core is used, high sensitivity can be obtained by applying a noisy magnetic field to the core and the core, and the distance between the magnet and the detection switch can be increased, so the rubber magnet placed on the normal plane can be used. It is suitable as a magnetic sensor device for guiding and controlling unmanned vehicles along the belt.

(c) By fixing a magnet at a position on the floor or wall that indicates the stop position, the stop position of a stacker crane, elevator, automatic guided vehicle, etc. can be controlled.

) The output signal is a stepped DC voltage, and the shape of the output characteristics can be arbitrarily selected by the arrangement of the saturable cores.

For example, for driving control of an unmanned vehicle, characteristics suitable for control can be easily obtained by arranging them finely in the center and coarsely toward the edges.

(e) The circuit configuration is relatively simple and the response speed is fast.

(F) The right end or the left end of the magnetizing body can be selectively detected depending on the direction in which a constant current is passed through the resistor group, which is useful for branch control in unmanned vehicle running.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing a basic embodiment of the present invention, Fig. 2 is an output characteristic diagram showing its operation, Fig. 3 is an output characteristic diagram showing a modified embodiment of the invention, and Fig. 4 is a saturable A characteristic diagram showing the operation of the coil, Fig. 5 is a plan view showing an example in which the present invention is used for trajectory control of an unmanned vehicle, and Fig. 6 shows an example in which the present invention is used in accurate stopping position control of an unmanned vehicle. FIG. L1-Ln...Saturable coil, O20...High frequency oscillator, R8...Series resistance, D1-Dn...Detection switch circuit, R1-Rn-1...Output resistance, CT...
Constant current circuit, ■. ...Constant current, M...Magnetizing body.

Claims (1)

[Claims] A large number of saturable coils whose inductance changes due to magnetism are arranged in a row, a voltage is supplied from a high frequency oscillator to each of the above saturable coils through a series resistor, and changes in inductance are detected to each of the above saturable coils. A detection switch circuit that turns on and off is provided, and the output terminals of the adjacent detection switch circuits are connected to each other with an output resistor (including one whose resistance value is 0), and a group of output resistors connected in series is connected to each other. A multiple magnetic detection switch that supplies a constant current and extracts a DC voltage from the output resistor group according to the position of the magnet.