JPS586127B2 - length measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a length measuring device that converts length into an electrical signal using magnetostrictive wires.

An object of the present invention is to provide a length measuring device with a simple structure and high accuracy.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, 1 is a magnetostrictive wire made of a magnetic material such as Ni-SPANCNi into a linear shape, 10 is a reel of the magnetostrictive wire 1, and the magnetostrictive wire 1 is configured to be freely drawn out from this reel in the direction of the arrow. There is.

Reference numeral 2 denotes an excitation means disposed on the reel 2 side of the magnetostrictive wire 1 and generates an ultrasonic signal within the magnetostrictive wire 1, and numeral 3 denotes a receiving means disposed on the reel 2 side of the magnetostrictive wire 1.

In this embodiment, an example is shown in which the excitation means 2 and the reception means 3 are both constituted by coils wound around the magnetostrictive wire 1.

OS is an excitation pulse generator whose output pulse PE is applied to the excitation means 2 and also to a set terminal S of a flip-flop circuit FF and a monostable multivibrator M, which will be described later.

OP is a comparator amplifier that compares the detection signal e1 from the receiving means 3 with the set voltage Es, and when c1>Es, amplifies the deviation and sends it to the reset terminal R of the flip-flop circuit FF via the gate circuit G. Apply.

The output signal of the monostable multivibrator M is the gate circuit G.
is applied to control the opening and closing of the gate circuit G.

For example, a hard metal material is fixed to one end 11 of the magnetostrictive wire 1 so that an ultrasonic signal is reflected, and a mark is provided to serve as a reference point when measuring the length.

In the device configured as described above, when measuring a certain length, the magnetostrictive wire 1 is pulled out from the reel 10, one end 11 of the magnetostrictive wire 1 is applied to the base point of the object to be measured (not shown), and the excitation means 2 and the receiving means are connected. 3 and the other point on the object to be measured.

This operation is similar to measuring length with a tape measure.

After setting in this manner, the excitation pulse PE is applied from the excitation pulse generator OS to the excitation means 2 as shown in FIG. 2A.

When an excitation pulse is applied to the excitation means 2, an ultrasonic signal is generated inside the magnetostrictive wire 1 due to the so-called Joule effect, and this signal propagates toward one end of the magnetostrictive wire 1.

This ultrasonic signal is reflected at one end 11 of the magnetostrictive wire 1 and returns to the excitation means 2 side.

Here, when the ultrasonic signal passes through the magnetostrictive wire 1, the so-called Villari effect causes the second transmission means 3 to pass through the magnetostrictive wire 1.
As shown in the figure, pulse-like voltage signals e and er(e
is generated by the outward ultrasonic signal, and er is generated by the return ultrasonic signal (reflected wave).

The excitation pulse PE is applied to the set terminals of the monostable multi-bibreak M and the flip-flop circuit FF,
These are set in the state shown in FIG. 2C and D.

The monostable multivibrator M closes the gate circuit G for a time τ that is slightly longer than the time until the pulse voltage signal e is generated in the receiving means 3.

Therefore, the pulse voltage signal e generated in the receiving means 3 passes through the gate circuit G, and the flip-flop circuit FF is reset by this pulse voltage signal er as shown in FIG.

Now, if we assume that an ultrasonic signal is generated within the magnetostrictive wire 1 at the same time as the excitation pulse PE is applied to the excitation means 2, this ultrasonic signal is reflected at one end of the magnetostrictive wire 1 and reaches the receiving means 3. The time t can be expressed by equation (1).

However, vs: Speed at which the ultrasonic signal propagates in the magnetostrictive wire 1 l: Length to be measured Therefore, as shown in FIG. It is possible to obtain a time width signal with

Therefore, by counting this time width t, the measurement length l can be measured.

Note that in this embodiment, the flip-flop circuit FF
may be set by the first pulse e1 from the receiving means.

In this case, the measurement length l is set to the distance between the receiving coil 3 and one end 11.

FIG. 3 is a block diagram showing another embodiment of the present invention.

In this embodiment two receiving means 31, 32 are coupled to the magnetostrictive wire 1 and are arranged at a distance from each other by a known length lo.
The measuring length l is set between one end 11 of the magnetostrictive wire 1 and the receiving means 32.

In such a configuration, when the excitation pulse PE is applied to the excitation means 2 as shown in FIG. 4A, the first reception means 31
From there, pulse-like signals e1 and e1r as shown in the opening of Fig. 4 are generated.
However, pulse-like signals e2 and e2r as shown in FIG. 4C are also obtained from the second receiving means 32, respectively.

Here, the time interval t3 between the first pulse e1 obtained from the first receiving means 31 and the second pulse el due to its reflected wave, and the first pulse e1 obtained from the second receiving means 32.
The time interval t2 between the second pulse e2 and the second pulse c2 due to its reflected wave can be expressed by equations (2) and (3).

From equations (2) and (3), the measured length l can be expressed by equation (4).

Therefore, the first receiving means 31 and the second receiving means 32
By using the pulse signals obtained from t3 and t2 and performing calculations such as equation (4), the measured length l can be found.

As is clear from equation (4), the device configured in this manner is not affected by the propagation velocity v3 of the ultrasonic signal and can measure the length l.
can be used to improve measurement accuracy.

In this embodiment, the first pulse signals e1, e obtained from the first receiving means 31 and the second receiving means 32
If ζ is rubbed to obtain an interval t1 of 2, t1 can be expressed by equation (5).

Therefore, the measured length l can be determined from equations (3) and (5) by performing calculations such as equation (6).

FIG. 5 is a block diagram showing an example of the case where the present invention is applied to a level meter.

One end 11 of the magnetostrictive wire 1 is connected to a float FL that moves up and down with the level, and both the excitation means 2 and the reception means 3 are fixed to the block BL.

Now, when the float FL moves up and down, the magnetostrictive wire 1 is wound up and let out by the reel 10, and therefore the length L between the receiving means 3 and one end 11 of the magnetostrictive wire 1 changes.

This length L is measured using the same measurement principle as in FIG. 1 or 3, and the level can be determined.

In each of the above-mentioned embodiments, the excitation means and the reception means are separately configured, but it is also possible to use one coil for both purposes.

As explained above, according to the present invention, it is possible to realize a length measuring device with a simple structure that can easily convert the length to be measured into an electrical signal.

[Brief explanation of drawings]

FIG. 1 is a configuration block diagram showing one embodiment of the present invention, and FIG.
3 is a configuration block diagram showing another embodiment of the present invention, FIG. 4 is an operating waveform diagram of the device shown in FIG. 3, and FIG. 5 is a level meter of the present invention. FIG. 1... Magnetostrictive wire, 2... Excitation means, 3.
...Receiving means, 10...Reel, OP.
... Comparison amplifier, G ... Gate circuit, O
S...Excitation pulse generator, FF...Flip-flop circuit.

Claims (1)

[Claims] 1. A reel, a magnetostrictive wire made of magnetostrictive material, one end of which is wound onto the reel, the other end of which is freely drawn out from the reel, and the other end of which is configured to reflect ultrasonic signals. an excitation means installed on the reel side and coupled to the magnetostrictive wire to generate an ultrasonic signal in the magnetostrictive wire so that the magnetostrictive wire is movable; an exciting means installed on the reel side so that the magnetostrictive wire is movable receiving means for receiving an ultrasonic signal coupled to the magnetostrictive wire and propagating through the magnetostrictive wire, the magnetostrictive wire having a distance between the excitation means and/or the receiving means and one end of the magnetostrictive wire corresponding to a measurement length; The measured length is determined by using a signal related to the time it takes for an ultrasonic signal drawn from the reel and generated in the magnetostrictive wire by the excitation means to reflect at the one end and reach the receiving means. Length measuring device. 2. The length measuring device according to claim 1, wherein the same means serves as both the excitation means and the reception means.