JPH0380247B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a position detection circuit for a magnetostrictive potentiometer using reflected waves.

[Background of the invention]

FIG. 3 shows the principle configuration of a reflection type magnetostrictive potentiometer. In the figure, 1 is a magnetostrictive wire, and 21 is a drive coil for generating magnetostrictive waves, which is fixed to one end of the magnetostrictive wire 1. Reference numeral 22 denotes a detection coil for detecting magnetostrictive waves, which is movably arranged at the center of the magnetostrictive wire 1.

In such a configuration, by applying an excitation pulse to the drive coil 21 as shown in FIG. 4A, a positive direct wave is generated as shown in FIG.
By measuring the arrival times t1 and t2 of the negative polarity reflected waves reflected at the end of the magnetostrictive wire 1, the detection coil 2
The position X of 2 can be found.

In order to determine the position
An application was filed for the circuit configuration as No. 219316 (Japanese Unexamined Patent Publication No. 61-97523). However, it has been found that the circuit of this previously applied application has the disadvantage of a detection error and a large temperature coefficient because the number of circuit elements for determining t1 and t2 is different.

[Problem that the invention seeks to solve]

The present invention has been made for the purpose of solving the above-mentioned problems of the position detection circuit of the previously applied application, and to obtain a detection circuit having a simpler circuit configuration than that of the previously applied position detection circuit.

[Means for solving problems]

In order to achieve the above object, the present invention has a first magnetostrictive wire, which has separate positive and negative threshold levels, and is provided with a distorted wave signal from a detection coil movably arranged on the magnetostrictive wire. a second comparator, a pulse generator that supplies an excitation pulse to a drive coil fixed to one end of the magnetostrictive wire; the output signal of the pulse generator is set, and the output of the first comparator is applied to a clock terminal; a first flip-flop, the output of the second comparator being applied to the clock terminal, the output being applied to the data input terminal and reset by the Q output of the first flip-flop; a second flip-flop; It is set by the output signal of the generator and the second clock is connected to the clock terminal.
a third flip-flop to which the output of the flip-flop is applied;
It is composed of an arithmetic circuit that performs a predetermined arithmetic operation on the Q output of the flop to obtain an analog signal corresponding to the position of the detection coil. Examples will be described below.

FIG. 1 is a circuit diagram of an embodiment of a position detection circuit according to the present invention. In the figure, COMP-1,
COMP-2 is a first and second voltage comparator with threshold levels of +Vth and -Vth, to which the output signal (voltage waveform) of the detection coil 22 explained in Fig. 3 is commonly given. . FF-1 to FF-3
are respectively edge-trigger type flip-flops, and OSC supplies excitation pulses to the drive coil 21 explained in FIG. It is a pulse generator to send. The clock terminal C of FF-1 receives the output of the comparator COMP-1,
Clock terminal C of FF-2 receives the output of comparator COMP-2. FF-2 is reset by receiving the Q output of FF-1 at its R terminal. The output of FF-2 is applied to the data input terminal D and also to the clock terminal C of FF-3. The data input terminal D and reset terminal R of FF-1, the set terminal S of FF-2, and the data input terminal D and reset terminal R of FF-3 are respectively connected to the reference potential point of the circuit. OP is an arithmetic circuit that calculates the position (displacement) X of the detection coil 22 shown in FIG. The value corresponding to (t1−t2)/(t1
+t2) and outputs it as an analog signal. Mono multivibrator MM receives the Q output of FF-3, outputs a pulse with a certain time width, and supplies this as a peak hold signal to arithmetic circuit OP.
The operation of the position detection circuit in such a configuration will be explained below using the time chart shown in FIG.

When the excitation pulse shown in FIG. 2A is generated from the pulse generator OSC, the drive coil 21 shown in FIG. The outputs become "H" as shown in FIG. 2, E and G, respectively. FF-1
When the Q output of becomes “H” level, FF-
2 is reset, and its Q output goes to the "H" level as shown in FIG.

By energizing the drive coil 21 with the excitation pulse shown in FIG. 2A, distorted waves are generated in the magnetostrictive wire as explained in FIG. 4. This distorted wave is detected by the detection coil 22 as a direct wave and a reflected wave of the distorted wave signal, as shown in FIG. 2B. This distorted wave detection signal is +
Vth, added to comparator COMP-1 and comparator COMP-2 with threshold levels of -Vth,
COMP-1 is also
COMP-2 outputs pulse signals such as β in FIG. 2, respectively.

The timing of arrival of the true direct wave and the reflected wave is at the rising edge of the pulses α and β shown in FIG. 2A and 2D. Pulse α output by comparator COMP-1 is FF
-1 is applied to the terminal C of FF-1, so that the Q output of FF-1 becomes "L" level. Therefore, as shown in FIG. 2E, the period during which the Q output of FF-1 is at the "H" level corresponds to the time t1 from when the excitation pulse is generated until the direct wave of distortion reaches the detection coil 22.

On the other hand, the pulse width signal corresponding to the time t2 until the pulse β reaches the detection coil 22 is FF-3
More can be obtained. Its operation is as follows. The output pulse of the comparator COMP-2 is given to the clock terminal C of FF-2, but the output of FF-2 is
By receiving the second output pulse of the comparator COMP-2 as shown in D of the figure, it becomes "L" level as shown in F of the same figure, and then rises with the generated reflected wave pulse β and becomes "H" level. Become. FF−
3 uses the output of FF-2 as a clock input.
As a result, the Q output of FF-3 becomes "L" level at the rise of the output of FF-2, that is, the reflected wave pulse β. Therefore, the Q output of FF-3 is the time from when the excitation pulse is generated until the reflected wave of the distorted wave is detected by the detection coil 22, as shown in Fig. 2.
It becomes a pulse width signal corresponding to t2. This pulse width signal is connected to the arithmetic circuit OP and the mono multivibrator.
Given to MM.

The mono multivibrator MM is triggered by the falling edge of the pulse width signal obtained from FF-3, and the second
Generates a pulse with a constant time width as shown in Figure H.
The arithmetic circuit OP outputs a signal (data ), and when the peak hold signal from the mono multivibrator MM is given, the signal at that time is held, and based on this, the value (t1 - t2) / (t1) corresponding to the position of the detection coil 22 is created.
+t2) and outputs the result as an analog signal.

〔Effect of the invention〕

In the earlier application mentioned above, the direct wave α and the reflected wave β
In order to detect the arrival time of
t2)/(t1+t2) and has a detection error and a temperature coefficient. In contrast, in the circuit of the present invention, there is only a delay of one flip-flop in detecting the direct wave α and the reflected wave β, so the detection error and temperature coefficient are small (1/2 of that of the previous application). , and a position detection circuit with a simple configuration can be obtained.

[Brief explanation of drawings]

Fig. 1 is a connection diagram showing an embodiment of the position detection circuit according to the present invention, Fig. 2 is a time chart for explaining the operation of the circuit shown in Fig. 1, and Fig. 3 is the principle of a reflective magnetostrictive potentiometer. The configuration diagram and FIG. 4 are operational waveform diagrams of the circuit of FIG. 3. 1... Magnetostrictive wire, 21... Drive coil, 22...
Detection coil, COMP-1, COMP-2... comparator, FF-1 to FF-3... flip-flop,
MM...Mono multivibrator, OP...Arithmetic circuit.

Claims (1)

[Claims] 1 first and second comparators each having separate positive and negative threshold levels and receiving distorted wave detection signals from detection coils movably disposed on the magnetostrictive wire; a pulse generator which supplies excitation pulses to a drive coil fixed at one end; a first flip-flop which is set by the output signal of the pulse generator and whose clock terminal receives the output of the first comparator; The output of the second comparator is applied to the data input terminal, and the Q of the first flip-flop is applied.
a second flip-flop reset at the output;
a third flip-flop set by the output signal of the pulse generator and having a clock terminal supplied with the output of the second flip-flop;
and a calculation circuit for performing a predetermined calculation on the Q output of the third flip-flop to obtain an analog signal corresponding to the position of the detection coil.