JPS6046576B2 - non-contact switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a switch that incorporates a sensor IC such as a Hall IC that is driven by the strength or weakness of a magnetic field. To provide a non-contact switch that can prevent inoperability and chattering.

As shown in FIG. 1, a conventional non-contact switch houses a sensor IC 2 in a switch container 1.

Press button B on the magneto-electric transducer part inside for 3 seconds ▼1, -
L, ^,, eyes LIC.

There is one that extracts the switch output from the switch. In a non-contact switch with such a configuration, each terminal P, Po
, the load circuit LD connected to Po, or the sensor IC if the wiring length to the power supply E becomes long.

The operating sensitivity of the device changes due to the occurrence of parasitic oscillation. In other words, if the power supply E is far away and the inductivity of the wiring increases, the parasitic oscillation strength will increase and the operation will become unstable accordingly.This corresponds to the equivalent circuit shown in FIG. 2, for example. According to the table below as an example, the inductance L
As the value changes, the strength of the magnetic field changes both when the sensor IC2 is closed and when the circuit is open, and a remarkable change is observed especially when the circuit is closed.

When it reaches 15 μH, the output of the sensor IC 2 will cause chattering at 700G (Gauss). [G]: Relationship table between Gaussian power supply inductance and magnetic field strength Also, when multiple non-contact switches with built-in sensor IC2 are connected to the same power supply E, parasitic oscillations are more likely to occur, making the operation of the non-contact switches unstable. It was something to do.

The present invention has been made in view of these conventional drawbacks and to improve them. Hereinafter, an embodiment of the non-contact switch of the present invention will be described with reference to FIG. 3, in which the same parts as those of the conventional example in FIG. 1 are given the same reference numerals.

1 is the switch container, 2 is the sensor IC, B is the push button, Mg
is a permanent magnet, R is a resistor, C is a capacitor, LD is a load circuit, E is a power supply, and Pl, P2, and P3 are terminals.

The sensor IC2 is housed in the switch container 1, and the sensor I
An output is taken out from the sensor IC 2 by a permanent magnet that is placed near a magnetoelectric transducer such as a Hall element C2 and is used as a driver that moves in response to the pressing and releasing of the push button B.

Of the lead wires of sensor IC2, the positive wire is connected to terminal P1 via resistor R, the negative wire is connected to terminal P3, and hole I
A line connected to a switching element Tr built in C is connected to a terminal P2, and a capacitor C is further connected between terminals Pl and P2. In addition, a permanent magnet Mg can also be used with an appropriate reversing mechanism including a handle instead of a push button B or a coil spring.
The operation may be self-maintained. Alternatively, a permanent magnet may be fixed to the container 1, and a magnetic shield provided between the sensor IC 2 and the sensor IC 2 may be used as a driver to open and close the container with a push button B. In the non-contact switch having such a configuration, a power source E is connected between the terminals Pl and P2 as shown in FIG.
By pressing and releasing the push button B, the permanent magnet Mg is actuated in response to move toward and away from the sensor IC2.

The capacitor C prevents parasitic oscillation occurring in the electric circuit of the Hall IC, power supply E, and load LD. In other words, a Hall IC has an IC configuration in which a Hall element, an amplification circuit, a snap circuit, and an output circuit are formed on the same belt, so if the line length becomes long and becomes inductive, the IC configuration and load LD , depending on the circuit configuration of the power source E, parasitic oscillations occur to a greater or lesser extent, causing a change in sensitivity, and as the line length increases, naturally the line resistance also increases, causing a similar change in sensitivity.

Even if the line length is short, it will occur if the wire is thin. Therefore, when forming a sensor circuit using sensor IC2 such as a Hall IC, if the sensitivity of sensor IC2 changes depending on the construction conditions, it will be extremely difficult to use, but capacitor C can prevent parasitic development. This is especially effective because it can be used freely without such construction considerations. Especially in view of the future trend in which sensors will be integrated into ICs, this effect will be of extremely high value in the field of control technology. The next resistor is a resistor for protecting rush current flowing through the IC.

Note that the resistor R can also function as a low-pass filter in conjunction with the capacitor C for preventing parasitic oscillation, and can protect the surge IC 2 from malfunction and destruction due to external surges.

The capacitor C above is for preventing parasitic oscillation, so it is 1000 [P
F) It functions satisfactorily with a smaller capacitance than the following low-pass filters.For example, it has been confirmed that the sensitivity change is almost zero even when the line inductance becomes several tens of μH. It can be said that there is no change, and the effect is extremely remarkable, as it is stable even with an inductance 1,000 times higher than the conventional one, which chatters at more than 10 μH.

Furthermore, by accommodating the capacitor C and resistor R in the switch container 1, it can be connected to the sensor IC 2 at the shortest distance possible, and as a non-contact switch, no external connection is required, making installation of the non-contact switch easy. In addition, the capacitor C is located at the position closest to the sensor IC2.
can also be connected between the lead wires of the power supply terminals to cancel out all the effects of stray inductance of the wiring. In this case, the effects of preventing a decrease in sensitivity and parasitic oscillation can be maximized.

Therefore, the non-contact switch incorporating the sensor IC 2 can be used extremely stably regardless of the installation state.

Further, although it is rare for the conductor resistance of the wiring to reach several tens of ohms, a decrease in sensitivity of the sensor IC 2 in this case can be prevented in the same manner as described above. In addition to the sensor IC 2, the present invention can also be applied to various sensor ICs that use elements such as photoelectric conversion elements, have similar effects, and are included in the present invention. As explained above, according to the non-contact switch of the present invention, the sensor IC 2 is accommodated in the switch container 1, and the sensor IC 2 is driven by the driver that responds to the press and release of the push button B to obtain the switch output. The contact switch has a configuration in which a resistor R is connected in series with the power supply E that drives the sensor IC2, and a capacitor C for preventing parasitic oscillation is connected in parallel between the power supply terminals of the sensor IC2. IC
By preventing parasitic oscillation caused by the sensor circuit configuration of the load LD and power supply E, it is possible to prevent sensitivity changes and chattering of the sensor IC 2 due to the length and shortness of the wiring to the non-contact switch. It is a non-contact switch that does not cause abnormal operation even when connected together.
Its use can be made extremely stable.

[Brief explanation of the drawing]

1 and 2 show a conventional example, with FIG. 1 being a circuit diagram and FIG. 2 being an explanatory diagram. FIG. 3 is a circuit diagram showing an embodiment of the non-contact switch of the present invention. 1...Container, 2...Sensor IC
、． B...Push button, Mg...Permanent magnet,
R...Resistance, C...Capacitor, E...
·····power supply.

Claims (1)

[Scope of Claims] 1. A non-contact switch in which a sensor IC is housed in a switch container, and a driver responsive to press and release of a push button drives the sensor IC to obtain a switch output. A non-contact switch that has a configuration in which a resistor is connected in series with a power supply, and a capacitor for preventing parasitic oscillation is connected in parallel between the power supply terminals of a sensor IC. 2. A non-contact switch according to claim 1, in which the Hall IC is driven by the approach and separation of a permanent magnet. 3. A non-contact switch according to claim 1 or 2, wherein a resistor and a capacitor are housed in a container of the switch.