JPS6352321B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a height measuring device that measures height using an electrical method.

Conventionally known height meters are composed of a column with a scale and an overhead board that can be moved along the column. The scale is measured by touching the top of the head.

Since such conventionally known height meters measure the scale, they suffer from measurement errors and have the disadvantage that highly accurate height measurements cannot be performed.

The present invention seeks to realize a height measuring instrument that does not have these drawbacks.

Fig. 1 is an outline drawing showing one embodiment of the present invention, Fig. 2 is an outline drawing showing an embodiment of the present invention;
The figure shows its electrical block diagram. In these figures, 1 is a base, 2 is a column, 3 is an overhead board that moves along the column, 4 is a magnetostrictive wire stretched parallel to column 2, and both ends are lightly connected to prevent mechanical vibration from being transmitted. Supported. This magnetostrictive wire 4 is coupled with an excitation means 50 that moves together with the overhead plate 3 and generates an ultrasonic signal within the magnetostrictive wire 4 . Further, receiving means 61 and 62 for receiving ultrasonic signals are coupled to both ends of the magnetostrictive wire 4. In this embodiment, as shown in FIG. 2, the excitation means 50 includes a transformer 51 constituted by a toroidal iron core through which the magnetostrictive wire 4 passes and the magnetostrictive wire serves as a primary winding. , and an excitation coil 53 to which a signal generated in the secondary winding 52 of the transformer 51 is applied.

OS is an excitation pulse generator whose output signal is applied to both ends of the magnetostrictive wire 4. FF ₁ and FF ₂ are both flip-flop circuits, to which a signal from an excitation pulse generator OS is applied to a set terminal S, respectively. Also, flip-flop circuit FF ₁
The signal from the receiving means 61 is applied to the reset terminal R, and the signal from the receiving means 62 is applied to the reset terminal of the flip-flop circuit _FF2 . CK is an arithmetic circuit to which time width signals from the flip-flop circuits FF ₁ and FF ₂ are applied, and IN is an indicator on which the arithmetic results of the arithmetic circuit CK are displayed in analog or digital form.

The operation of the apparatus configured in this way will be explained next.

The person to be measured MH is made to stand upright on the base 1, and the overhead board 3 is brought into contact with the top of the head of the person to be measured. This operation is similar to the measuring method of a conventionally known height meter. In this state, the excitation pulse generator OS outputs an excitation pulse current i _p at regular intervals. This excitation pulse current
i _p flows through the magnetostrictive wire 4. In the transformer 51 that moves together with the overhead plate 3, a current is applied to the magnetostrictive wire 4.
When i _p flows, a current i ₂ as shown in equation (1) flows through the secondary coil 52.

i ₂ = i _p /n ₂ (1) However, n ₂ is the number of turns of the secondary coil 52. This current i ₂ is the excitation coil 5 coupled to the magnetostrictive wire 4.
3 as an excitation pulse current. Excitation coil 5
When a vibration pulse signal is applied to magnetostrictive wire 3, an ultrasonic signal is generated inside magnetostrictive wire 4 at the position of excitation coil 53 due to the so-called Joule effect. Such ultrasonic signal generation operation is performed under the same conditions no matter where the excitation coil 53 is located on the magnetostrictive wire 4. Excitation pulse generator like this
The pulse current i _p from the OS generates an ultrasonic signal within the magnetostrictive wire 4 at the position of the excitation coil 53 via a transformer 51 movable along the magnetostrictive wire 4, and generates an ultrasonic signal in each flip-flop circuit FF. ₁ ,
Set FF ₂ . Within the magnetostrictive wire 4,
The ultrasonic signal generated at the position of the excitation coil 53 is
The magnetostrictive wire 4 is used as a propagation path to propagate toward both ends thereof, and is detected by receiving means 61 and 62 provided near both ends, respectively. In this embodiment, a coil is used as the receiving means, so when an ultrasonic signal passes through the magnetostrictive wire 4 close to this coil, pulse-like voltages e ₁ , e are generated due to the so-called Villari effect. ₂ is generated and applied to the reset terminal of each flip-flop circuit FF ₁ and FF ₂ .

Now, if it is assumed that an ultrasonic signal is generated at the position of the excitation coil 53 at the same time that the excitation pulse current i _p flows through the magnetostrictive wire 4, this ultrasonic signal will flow through the magnetostrictive wire 4.
The propagation times t ₁ and t ₂ for the signals to propagate and reach the positions of the respective receiving means 61 and 62 can be expressed by equations (2) and (3).

t ₁ = x/v _s (2) t ₂ = L-x/v _s (3) where, v _s : Speed at which the ultrasonic signal propagates within the magnetostrictive wire 4 x : Measured height (excitation coil 53 and receiving Means 61
L: Distance between receiving means 61, 62 Pulse width signals having time widths corresponding to the propagation times _{t1 , t2} described above are obtained from each flip-flop circuit FF1, _FF2 . The signal is a calculation circuit
Applied to CK. The arithmetic circuit CK inputs these two time width signals and calculates the height x by calculating, for example, equation (4).

t ₁ − _{t 2} / _{t 1} + _{t 2} =2x− _{L /} L Height x, unaffected by signal propagation velocity v _s
It is in a place where it can be measured. Furthermore, since each of the receiving means 61 and 62 receives ultrasonic signals of approximately the same amplitude propagating from the excitation means 50, the change in the amplitude value (the change in the amplitude value is caused by the coupling between the excitation means and the magnetostrictive line) measurement errors that intervene in the propagation time can be canceled out. Therefore, it is possible to eliminate the influence of changes in the degree of coupling between the excitation means and the magnetostrictive wires that occurs as the overhead plate moves. Then, the indicator IN indicates the result of this calculation.

In the above embodiment, both the vibrating means and the receiving means have a structure in which they are wound around magnetostrictive wires, but other structures may be used, or permanent magnets may be placed near these means. , thereby applying a bias to the magnetostrictive wire to increase excitation or reception efficiency. Moreover, although the case of measuring height has been described here as an example, it is of course applicable to measuring sitting height and other lengths.

As explained above, according to the present invention, it is easy to digitally display measured values, there is no measurement error, and the propagation speed of the ultrasonic signal propagating in the magnetostrictive wire is changed due to changes in ambient temperature, etc. Since it is not affected by changes in V _s , a height measuring device with high measurement accuracy can be realized. Furthermore, according to the present invention, height can be measured with high accuracy without being affected by changes in length due to linear expansion of the magnetostrictive wire 4 due to temperature changes or the like.

That is, if the linear expansion coefficient of the magnetostrictive wire 4 is α and the temperature change is Δt, and if we rewrite equation (4) taking this into consideration, we get equation (5), which is t ₁ − t ₂ /t ₁ +t ₂ By performing the calculation, it is also possible to eliminate the influence caused by a change in the length of the magnetostrictive wire 1 itself.

t ₁ - t ₂ / t ₁ + t ₂ = 2X (1 + αΔt) - L (1 + αΔt) /
L(1+αΔt)=2X−L/L (5)

[Brief explanation of drawings]

Fig. 1 is an outline drawing showing one embodiment of the present invention, Fig. 2 is an outline drawing showing an embodiment of the present invention;
The figure is its electrical block diagram. 1... Base, 2... Support, 3... Overhead board, 4...
... Magnetostrictive wire, 50 ... Excitation means, 61, 62 ... Receiving means, FF ₁ , FF ₂ ... Flip-flop circuit,
CK...Arithmetic circuit, OS...Pulse generator, IN...
…Indicator.

Claims (1)

[Scope of Claims] 1. A height measuring device comprising a column and an overhead plate movable along the column, in which a magnetostrictive wire stretched approximately parallel to the column and a magnetostrictive line that moves with the overhead plate an excitation means coupled to the magnetostrictive wire; first and second receiving means for receiving ultrasonic signals that are coupled to the magnetostrictive wire near both ends of the magnetostrictive wire and propagated through the magnetostrictive wire; Until the ultrasonic signal generated in the magnetostrictive wire by the excitation means by inputting the signal related to the signal and the signals from the first and second receiving means reaches the first and second receiving means. circuit means for obtaining the propagation times t ₁ , t ₂ of
A calculation circuit for determining the height by inputting signals related to the propagation times t ₁ and t ₂ and performing calculations including at least calculations of t ₁ −t ₂ /t ₁ +t ₂ . measuring device. 2. The excitation means is composed of a transformer in which the magnetostrictive wire is coupled to serve as a primary coil, and an excitation coil to which a signal generated in the secondary coil of this transformer is applied and coupled to the magnetostrictive wire, and the magnetostrictive wire is 2. A height measuring device according to claim 1, wherein an excitation pulse signal is applied to the height measuring device.