JPH0674789A - Displacement detector - Google Patents

Abstract

PURPOSE:To obtain a displacement detector being mounted as an automobile component in which the position of an object can be detected highly accurately regardless of deterioration in detecting capacity at a detecting part due to temperature drift or attenuation of a transmission signal of the object. CONSTITUTION:An ultrasonic detecting part 1 is disposed at one end of a magnetostriction wire 2 and an ultrasonic signal detected through the detecting section 1 is converted through a binary encoding circuit 4 into a digital signal which is then subjected to arithmetic processing. Thus processed signals are converted, at final output stage, into analog signals through D/A converters 10, 11 in order to obtain average value outputs. This constitution detects the position of a magnet moving along the magnetostriction wire 2 and produces an electrical signal representative thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement detecting device for converting a mechanical displacement position or length into an electric signal.

[0002]

2. Description of the Related Art In a displacement detecting device of this type, a non-detecting portion is arranged at a point a certain distance away from the displacement detecting portion.
In a displacement detection device that emits a position signal such as the waveform B (solid line) of, the detection unit detects this signal,
By using the signal binarized through the binarization circuit, by measuring the time from the reference time to the arrival time of this binarized signal, it is possible to measure the distance between the non-detection body and the detection body. is there.

[0003]

However, in the above-mentioned conventional displacement detecting device, only the rising component or the falling component of the binarized signal is used, and the output value is caused by the temperature drift of the detection unit / non-detection unit. Is easily influenced by the ambient temperature, and even if the offset voltage of the binarization circuit changes, the output also fluctuates. For example, when using it for a displacement sensor for automobiles, the temperature dependence of the output voltage is poor. There is a problem that it cannot be mounted as an automobile part.

FIG. 5 is a waveform diagram when the detection capability of the detection section or the oscillation signal of the non-detection section changes. The waveform A is a reference pulse for measuring the detection section time, and the waveform B is a non-detection reference pulse. The detection unit transmission signal, waveform C, is a signal obtained by binarizing waveform B by a binarizing circuit. In such a waveform, when the detection unit detection capability or the non-detection unit transmission signal changes with temperature, the waveform B changes as shown by the wavy line in FIG. 5, and as a result, the waveform C also changes like the wavy line, and the original Measurement time t
Shifts to t ', causing a measurement error Δt. FIG. 6 is a waveform diagram when the offset voltage of the binarization circuit changes, and a measurement error Δt occurs when the original offset voltage value v changes to v ′ due to a temperature change.

The present invention is intended to solve such a conventional problem, and an object thereof is to provide an excellent displacement detecting device which can be mounted as an automobile part.

[0006]

In order to solve the above-mentioned problems, the present invention divides the detection signal of the detection unit into two components, a rising component and a falling component, and determines the temporal midpoint of the rising component and the falling component. The arithmetic circuit is used for the arithmetic operation, and the point is set as the position of the non-detection portion.

[0007]

With this configuration, the detection part detection signal is divided into its rising and falling edges, the arithmetic circuit section calculates the time midpoint between the rising component and the falling component, and this point is used as the measurement point, so that the temperature dependence is obtained. It is possible to provide an excellent displacement detection device having no property, and it can be mounted as an automobile part having an extremely wide operating temperature range.

[0008]

【Example】

(Embodiment 1) A displacement detecting device according to an embodiment of the present invention will be described with reference to FIG. In the figure, reference numeral 1 is an ultrasonic wave detecting portion provided at one end of the magnetostrictive wire 2. A magnet 3 is movable along the magnetostrictive line 2. The output of the ultrasonic wave detection unit 1 is connected to the binarization circuit 4. The rising component of the output of the binarization circuit 4 to the ultrasonic wave detecting unit 1 is used as a stop signal of the first pulse counter 5, and the falling component of the output is used as a stop signal of the second pulse counter 6. . A current output unit 7 applies a pulse current to the magnetostrictive line 2 and simultaneously serves as a start signal for the first and second pulse counters 5 and 6. Reference numeral 8 is an arithmetic processing unit that receives the output of the first pulse counter 5, and 9 is an arithmetic processing unit that receives the output of the second pulse counter 6. Reference numeral 10 is a D / A converter that receives the output of the arithmetic processing unit 8, 11 is a D / A converter that receives the output of the arithmetic processing unit 9, and 12 is a fixed resistance unit.

Next, the operation of the above embodiment will be described.
In the above embodiment, it is assumed that the movable magnet 3 is at the arbitrary position A. A pulse current is applied to the magnetostrictive wire 2 from the current output unit 7 to generate a magnetic field on the magnetostrictive wire 2, but at the point A, the magnet 3 causes magnetostriction, which causes mechanical twisting, which in turn generates ultrasonic waves. This is generally called the Wiedeman effect. This ultrasonic wave propagates on the magnetostrictive line 2 at the speed of sound, and the ultrasonic wave detection unit 1
Is reached t ₁ seconds after the pulse current is applied. The first pulse counter 5 and the second pulse counter 6 perform pulse counting using this signal as a start signal at the same time when the pulse current is applied from the current output unit 7. The count-up clock pulse at this time is the first and second clock pulses.
It is supplied from the pulse counters 5 and 6.

On the other hand, the ultrasonic wave signal from the magnet 3 is binarized by the binarization circuit 4 through the ultrasonic wave detecting section 1, and the rising component thereof is a stop signal for stopping the pulse counting of the first pulse counter 5. And its falling component becomes a stop signal for stopping the pulse counting of the second pulse counter 6. The respective data of the first and second pulse counters 5 and 6 stopped in this way are obtained by the arithmetic processing units 8 and 9, and this data is converted into analog output by the D / A converters 10 and 11. Furthermore, by averaging the two signals with the fixed resistance unit 12, the position of the magnet 3 can be detected without being easily influenced by the environmental temperature change.

The value of this output is periodically updated by periodically repeating the series of operations up to now, and even if the magnet 3 moves to the point B, the position change during the movement or the position of the point B is moved. Is output.

As described above, according to the present embodiment, two sets of counters, an arithmetic processing unit, and a D / A converter are driven by the rising component and the falling component of the output of the ultrasonic detecting unit, and the D / A of each of them is driven. By taking the average value of the output of the A converter, it is possible to make the ultrasonic detector less susceptible to the temperature change.

FIG. 2 is a waveform diagram when the present invention is embodied. A waveform A is a reference pulse for measuring the detection unit time, a waveform B is a non-detection unit transmission signal detected by the detection unit, and a waveform C is the waveform B. The signal binarized by the binarization circuit, the waveform D shows the rising component of the waveform C, and the waveform E shows the rising component of the waveform C.

Now, when the detection part detection capability or the non-detection part transmission signal changes with temperature, the waveform B changes and the waveforms C, D and E also change as shown by the broken line in FIG. However, by further averaging the signals counted at the timings of the waveforms D and E, even if the waveform B fluctuates, the waveform B is always
The measurement time t at the midpoint of is unchanged.

(Embodiment 2) FIG. 3 shows a displacement detecting device according to another embodiment of the present invention. In FIG. 3, numeral 13 further averages the outputs of the arithmetic processing unit 8 and the arithmetic processing unit 9. An arithmetic processing unit for arithmetic operation, 14 is a D / A converter which receives the output of the arithmetic processing unit 13.

Next, the operation of the above embodiment will be described. In this embodiment, the ultrasonic signal from the magnet 3 is binarized by the binarizing circuit 4 via the ultrasonic detector 1 and its rising component. Is a stop signal for stopping the pulse counting of the first pulse counter 5, and the falling component is a stop signal for stopping the pulse counting of the second pulse counter 6. The respective data of the first and second pulse counters 5 and 6 stopped in this way are obtained by the arithmetic processing units 8 and 9, and these digital processed signals are averaged by the arithmetic processing unit 13 to obtain D /
By converting into an analog output by the A converter 14, it becomes possible to detect the position of the magnet 3 unlikely to be affected by environmental temperature changes.

(Embodiment 3) FIG. 4 shows a displacement detecting device according to another embodiment of the present invention. In FIG. 4, reference numeral 41 denotes a large number of light receiving elements (eg CCDs) driven by a drive circuit 42. A light receiving element portion arranged in series and arranged to face a light emitting element portion 43 described later, and 43 is a light receiving element portion driven by a drive circuit and movable along the light receiving element portion 41.

Reference numeral 45 is a binarizing circuit for binarizing the output signal from the light receiving element section 41. The rising component of the output signal of the binarization circuit 45 is used as the stop signal of the first pulse counter 46, and the falling component of the output is used as the stop signal of the second pulse counter 47. Reference numeral 44 denotes a drive circuit for the light receiving element section 43, and at the same time,
It is also a start signal generating circuit for starting the first and second pulse counters 46, 47 with the drive signal of the light receiving element section 43. Reference numeral 48 is an arithmetic processing unit that receives the output of the first pulse counter 46, and 49 is the second pulse counter 4
This is an arithmetic processing unit for inputting 7.

Reference numeral 50 is an arithmetic processing unit for further averaging the outputs of the arithmetic processing units 48 and 49, and 51 is a D / A converter which receives the output of the arithmetic processing unit 50 as an input.

Next, the operation of the above embodiment will be described. In the above embodiment, the movable light emitting element section 43 is movable.
Is at an arbitrary position A. The light of the light emitting element portion is converted into an electric signal by the light receiving element portion 41 and input to the binarization circuit 45. The rising component of the output of the binarization circuit 45 causes the falling component of the output of the first pulse counter 46 to stop each pulse count of the second pulse counter 47.

The respective data of the first and second pulse counters 45 and 46 stopped in this way are obtained by the arithmetic processing units 48 and 49, and further, these processed signals are averaged by the arithmetic processing unit 50, and D By converting into an analog output by the / A converter 51, it becomes possible to detect the position of the light emitting element section 43 so that it is less affected by the environmental temperature. The value of this output is periodically updated by periodically repeating the series of operations up to now, and even if the light emitting element unit 43 moves to the point B, the change in the position of the movement or the point B Is output.

As described above, according to the above-described embodiment, two sets of D are used for the rising component and the falling component of the light receiving element output.
By taking the average value of the output of the / A converter, it is possible to make it less susceptible to the temperature drift of the light emitting element section and the light receiving element section.

[0023]

As described above, according to the present invention, the rising and falling components of the detection signal output of the detection unit are set at the midpoint in time in the arithmetic processing unit, so that they are very stable against temperature changes. The effect that the position can be detected is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a displacement detection device according to an embodiment of the present invention.

FIG. 2 is a signal waveform diagram of the device.

FIG. 3 is a block diagram showing a displacement detection device according to another embodiment of the present invention.

FIG. 4 is a block diagram showing a displacement detection device according to another embodiment of the present invention.

FIG. 5 is a signal waveform diagram of a conventional displacement detection device.

FIG. 6 is a signal waveform diagram of the main part of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic wave detector 2 Magnetostrictive wire 3 Magnet 4 Binarization circuit 5 First pulse counter 6 Second pulse counter 7 Current output section 8, 9, 13 Arithmetic processing section 10, 11, 14 D / A converter 41 Light reception Element unit 42 Drive circuit 43 Light emitting element unit 44 Start signal generation circuit 45 Binarization circuit 46 First pulse counter 47 Second pulse counter 48, 49, 50 Arithmetic processing unit 51 D / A converter

Claims (1)

[Claims] 1. A means for binarizing a signal generated by a non-detection body,
A displacement detecting device comprising means for calculating a temporal midpoint of the binarized signal from the rising component and the falling component of the binarized signal, and performing position detection calculation using the point as the position of the non-detection body.