JPS5855698Y2 - Magnetoelectric conversion type non-contact switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetoelectric conversion type non-contact switch, and more particularly to a non-contact switch that is improved to reduce the influence of residual voltage in a Hall element on contact operation and to operate reliably.

Conventionally, as this type of magnetoelectric conversion type non-contact switch, there are those that utilize resonance between an inductance and a capacitor, those that are integrated into an IC that utilizes the Hall effect, and those that utilize changes in magnetic flux of an inductance with an iron core.

However, with a switch that uses the Hall effect, the switch is
The strength of the magnetic field when it changes from FF to ON and from ON to O
There is a difference in the strength of the magnetic field when it becomes FF, and there are also inconveniences in use, such as the fact that the operating distance cannot be maintained in the case of magnet drive.

Furthermore, when a Hall element is integrated into an IC together with a bipolar transistor in order to form a Hall IC, it is difficult to make the output terminals of the Hall element completely geometrically symmetrical to each other. Even after applying a magnetic field and removing it, a residual voltage corresponding to the bias current will be generated at the output terminal.

Furthermore, if the Hall element is integrated into a Hall IC with a bipolar transistor, the Hall constant cannot be increased because of the compact size, and therefore the external magnetic field must be increased in order to obtain a predetermined Hall electromotive force. There are drawbacks.

The present invention combines a Hall element to which an output voltage corresponding to the opposite polarity of the residual voltage generated at the output terminal in the absence of an external magnetic field is given in advance, and a differential amplifier and a switching circuit that amplify the Hall element output voltage. By assembling the present invention as an integrated circuit, it is intended to eliminate the drawbacks of the conventional method and provide a magnetoelectric conversion type non-contact switch with stable switching operation.

The configuration of this invention will be explained with reference to an embodiment shown in the drawings.

As shown in FIGS. 1 and 2, the embodiment according to the present invention is comprised of a Hall element 1, a differential amplifier 2, and a switching circuit 5.

As shown in Figure 1, by flowing an appropriate current from terminal a to terminal A of the bias current IC, an output voltage corresponding to a residual voltage of negative polarity at Hall voltage terminal C and positive polarity at terminal d is generated in advance. The Hall element 1, which is configured as shown in FIG. A circuit is formed to operate the switch via a switching circuit 5 consisting of a Zener diode ZD and a transistor Q.

At this time, the Hall voltage terminal C has a positive polarity opposite to the residual voltage, and the terminal d has a negative polarity, canceling out the residual voltage and producing an even stronger output voltage.

Further, in the circuit configuration described above, the circuit of the differential amplifier 2 is formed as a single unit separated from the Hall element 1.

Furthermore, the Hall element 1 has the following characteristics in order to increase magnetic field detection sensitivity:
Figure 3.

As shown in FIG. 4, the Hall element pellet 6 is sandwiched between two ferromagnetic plates, such as permalloy plates 7 and 8, whose surfaces are insulated and bonded together using an insulating adhesive.

In the embodiment with the above configuration, the Hall voltage corresponding to the residual voltage given to the Hall element 1 in advance applies a negative voltage to the positive input terminal 3 and a positive voltage to the negative input terminal 4 of the differential amplifier 2, so that This amplifier 2 does not operate.

Next, since the Hall voltage due to the application of an external magnetic field to the Hall element has the opposite polarity to the previously given Hall voltage,
This pre-applied voltage is canceled to produce an output voltage, which drives the differential amplifier 2.

As mentioned above, since the Hall voltage corresponding to the opposite polarity of the residual voltage generated due to the switching operation is applied to the Hall element 1 in advance, the residual voltage generated when the external magnetic field associated with the switching operation is removed. The residual voltage is canceled out and no output is produced at the Hall voltage terminal.Therefore, the residual voltage drives the differential amplifier 2 to operate and has the effect of preventing malfunctions.

Further, the differential amplifier 2 is formed as a single circuit separate from the Hall element 1, and since both are not integrally integrated into an IC as in the conventional case, instability of operation of unknown cause can be eliminated.

Further, since the Hall element 1 can increase the magnetic field detection sensitivity by two to three times while remaining an inexpensive element, it has become possible to widen the stable operation range of switching.

Next, another embodiment will be described based on FIGS. 5 and 6.

FIG. 5 shows a case where the output of the previous embodiment is inverted by providing one to two stages of transistors in the switching circuit of the previous embodiment shown in FIG.

Further, FIG. 6 shows the circuit of this embodiment shown in FIG. 5 with an offset adjustment circuit R5 added thereto.

As explained above, in the present invention, a Hall element to which a Hall voltage corresponding to the opposite polarity of the residual voltage is applied in advance is applied with an external magnetic field accompanying switching to drive a differential amplifier and operate a switching circuit. Because it's a dirty thing,
The conventional malfunction due to residual voltage has been eliminated, and the Hall element and the differential amplifier circuit have been incorporated into separate units, so the conventional unstable operation of unknown causes can be eliminated. Since it uses a Hall element designed to increase magnetic field detection sensitivity, it has excellent practical effects such as being able to widen the stable operating range.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the relationship between bias current, external magnetic field, and Hall voltage of a Hall element, Fig. 2 is an electric circuit diagram according to an embodiment of the present invention, and Fig. 3 is a Hall element according to an embodiment of the present invention. FIG. 4 is a plan view showing the configuration of FIG. 5 and 6 are circuit diagrams of other embodiments of the present invention. 1... Hall element, 2... Differential amplifier, 3, 4... Input terminal of differential amplifier, 5...
... Switching circuit, 6 ... Hall element Perez), 7.8 ... Permalloy plate, a, l).
... Bias current terminal of Hall element, c, d...
... Hall voltage terminal, IC ... Hall current, Le ... external magnetic field.

Claims (2)

[Scope of utility model registration request] (1) Separate the Hall element from which an appropriate bias current has been passed in advance so that output voltages corresponding to a predetermined residual voltage are generated at their output terminals with opposite polarities in the absence of an external magnetic field. a differential amplifier formed into a single unit,
a switching circuit driven by the amplifier,
The Hall element is formed by adhering with an insulating adhesive a ferromagnetic plate such as a permalloy plate whose surfaces are insulated on both sides while sandwiching the element pellet, and a predetermined external magnetic field is applied to the Hall element. A magnetoelectric conversion type non-contact switch configured to reverse the output voltage generated by the bias current at the output end of the Hall element by applying pressure. (2) The differential amplifier includes an offset adjustment circuit, and the switching circuit includes an 02 circuit and a Zener diode connected to the base of the output transistor. Conversion type non-contact switch.