JPS58108422A - Omnidirectional vibration sensor - Google Patents

Abstract

PURPOSE:To enable omnidirectional vibrations to be sensed by a single vibration sensor, and permit the sensor to be utilized as a compact inexpensive seismometer sensor, by constituting an omnidirectional vibration sensor by a magnetic sensor provided on the end of a vibratile round rod spring, and a cylindrical magnet. CONSTITUTION:One end of a wire-like round rod spring 4 is vertically secured so as to act as a pendulum shaft. A magnetic sensor 5 such as a Hall element and a magnetic diode is mounted on the other end of the pendulum shaft 4 so as to serve also as the weight for the pendulum. A cylindrical magnet 6 is secured around the pendulum shaft 4 in order to apply a uniform magnetic field change to the magnetic sensor 5 with respect to the swing of the pendulum in any direction. If the pendulum spring 4 is fixed so that the magnetic sensor 5 is in the center of the magnet 6 or equally distant therefrom, the magnetic sensor 5 is subjected to a uniform magnetic change applied in all two-dimensional directions and therefore can sense omnidirectional vibrations.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a vibration detector that is small and has a simple structure, and can provide uniform vibration sensitivity in all two-dimensional directions.

(Background technology) Conventionally, vibration sensors used in seismometers, etc. have unidirectional sensitivity, and seismometers for disaster prevention, etc. require horizontal omnidirectional detectors, but there are no effective sensors that can be used alone. Currently, we use two horizontal unidirectional detectors as shown in Figure 1, installed in orthogonal directions, and use electronic circuits to amplify and perform vector calculations to generate vibration output in all directions. It has gained. Here, 1 is a leaf spring, 2 is a coil, and 3 is a magnet, which generates an induced voltage in the coil 2 as the leaf spring vibrates in the direction (A). Therefore, it requires two sets of detectors and two amplifiers, and is mechanically and electrically complex, including an arithmetic circuit for synthesizing them, and has the disadvantage of being large and expensive. Furthermore, since it uses magnetism, conventional structures had the disadvantage of being susceptible to the influence of surrounding magnetic fields.

(Problems to be solved by the invention) An object of the present invention is to solve these drawbacks and provide a vibration sensor that can obtain uniform vibration sensitivity in four secondary directions with one detector and is less affected by external magnetic fields. Its features are a round bar spring that is fixed vertically and can vibrate,
The omnidirectional vibration sensor includes a magnetic sensor provided at the tip thereof, and a cylindrical magnet fixed in a plane around the magnetic sensor to apply magnetic field changes to the magnetic sensor due to vibrations in two-dimensional arbitrary directions. Examples will be described below.

(Structure and operation of the invention) FIGS. 2(a) and 2(b) show embodiments of the present invention,
4 is a wire-like round bar spring, one end of which is fixed vertically to serve as a pendulum shaft, and 5 is a magnetic sensor such as a Hall element or a magnetic diode, which is attached to the tip of the pendulum shaft 4 and also serves as the weight of the pendulum. . In order to give a uniform magnetic field change to a magnetic sensor such as a 50 Hall element or a magnetic diode when the pendulum swings in any direction, six cylindrical magnets are fixed around the pendulum. Hereinafter, 5 is referred to as a magnetic sensor. An output lead wire 8 is drawn out from the vibration sensor 5. In the embodiment, the magnet 6 is magnetized in the diametrical direction of the magnet as shown.

In the first embodiment, as shown in FIG. 5 obtains the same vibration displacement in any direction in response to a constant vibration input.Therefore, the photographic spring 4 is arranged so that the magnetic sensor 5 is located at the center of the cylindrical magnet 6 or at a position equidistant from the cylindrical magnet 6. If it is fixed, the magnetic sensor 5 will receive uniform magnetic changes in all two-dimensional directions, and can detect vibrations in all directions.

As explained above, the conventional two detectors can be replaced with one, and only one amplifier circuit is required (there is also no need for a spectrum synthesis circuit, so the system can be constructed at a very low cost. Since the magnetic sensor 5 is surrounded by the cylindrical magnet 6, this has a shielding effect, and the magnetic sensor 5 itself is less affected by external magnetic fields, which is an advantage.

In the first embodiment, the description was made simply as detection of vibrations, but since the resonant frequency of the pendulum spring 4 can be freely changed by selecting the material, thickness, length, etc. It is effective as an accelerometer when used for vibration measurement, and can be used as a displacement meter when used in a region relatively higher than the resonance region.

3(a) and (b) show modified examples of the present invention, in which 10 is a stand, 12 is a first cylinder fixed to the stand 10, and 7 is a second cylinder, which is engaged with the first cylinder via a screw. The matching b cylindrical magnet 6 is the second
It is fixed to the inner circumference of the cylinder 7. It is assumed that the round bar 4 is fixed in alignment with the central axes of the cylinders 7 and 12.

As a practical problem, it is necessary to balance the variation in sensitivity to vibration, but in order to bring the cylindrical magnet 6 in FIGS. By changing the relative distance between the magnetic sensor 5 and the cylindrical magnet 6, the sensitivity can be mechanically adjusted.

(Effects of the Invention) The present invention can detect vibrations in all directions with a single device, and it is easy to appropriately design the resonance region of the spring depending on the application, so it can be designed as a seismic acceleration sensor. For example, it can be used as a small and inexpensive seismometer sensor. Furthermore, its structure makes it less susceptible to external magnetic fields.

[Brief explanation of the drawing]

Figures 1 (al and b) are structural examples of a conventional leaf spring type unidirectional vibration detector, Figures 2 (a) and (b) are structural examples of an omnidirectional vibration sensor according to the present invention, and Figure 3. (a) and (b)
1 is another structural example of the omnidirectional vibration sensor according to the present invention. 1...Plate spring, 2...Coil, 3...
...Magnet, (a) ... Sensitivity direction 4.
... Round bar spring, 5 ... Magnetic sensor (weight), 6 ... Cylindrical magnet, 7, 12 ...
Cylindrical Patent Applicant Oki Electric Industry Co., Ltd. Patent Application Agent Megumi Yamamoto - Procedural Amendment (Spontaneous) February 7, 1972 Commissioner of the Japan Patent Office Kazuo Wakasugi 1, Indication of Case 1988 Patent Application No. 206865 2, Brother Akira's name Omnidirectional vibration sensor 3, Relationship with the amended case Patent applicant name (029) Oki Electric Industry Co., Ltd. Claims column and details of the invention in the thermal specification Claims 6.310 and above (II) A round bar spring that is fixed vertically and can vibrate, a magnetic sensor provided at the tip of the spring, and a magnetic sensor provided around the magnetic sensor. An omnidirectional vibration sensor characterized by having a cylindrical magnet fixed in a plane and giving the magnetic sensor a magnetic field change due to vibration in two-dimensional arbitrary directions. (2) The cylindrical magnet is vertically aligned with a round bar spring as an axis. An omnidirectional vibration sensor according to claim 1, wherein the omnidirectional vibration sensor is adjustable in direction and the magnetic field applied to the magnetic sensor is adjustable.

Claims (1)

[Scope of Claims] (11) A round bar spring fixed vertically and capable of vibrating; a magnetic sensor provided at the tip of the spring; An omnidirectional vibration sensor comprising: a cylindrical magnet that is applied to a magnetic sensor. (2) The cylindrical magnet is vertically adjustable around a round bar spring, and the magnetic field applied to the vibration sensor can be adjusted. An omnidirectional vibration sensor according to claim 1.