DE1125666B - Shock meter, in particular seismograph - Google Patents

Description

Vibration meters, in particular seismographs The invention relates refer to a seismograph, geophone, or vibration meter Sensitivity. With such devices one maintains a vibratory system in such a way that a mass is movably suspended and during the to register vibrations temporarily as a resting body a sensor affected, which is in contact with the parts exposed to the vibration.

In the simple case the mass is suspended from a spring Weight is formed and thus represents a vibratory system. By earthquakes, by explosions, by foundation vibrations of machines or the like. This is System excited to vibrate in the rhythm of the shock wave. To you as much as possible to achieve a favorable course of the resonance curve of the oscillatable structure, the system is usually dampened.

Optical methods are common for registration, with z. B. a light beam is imaged on a photosensitive paper, which at a is reflected on the mirror attached to the weight. Every movement of the weight relative to the ground causes a deflection of the light beam, so that on the light-sensitive paper, which moves with a certain time advance curves corresponding to the vibrations are recorded.

Furthermore, electrical measurement methods have also become known. So had one associated with the weight of a permanent magnet in a Moving coil vibrates and the vibrating movement generates tensions in it. At rest, no tension is created, while with increasing size and the speed of deflection the level of the induced stress increases. This Method has the disadvantage that according to the speed of movement the arrangement is strongly frequency-dependent and none for different frequencies accurate amplitude measurement of ground movements is possible. Such measuring devices therefore make extensive corrections necessary.

The invention is based on the object, likewise a measurement to be carried out by electrical means, but which does not have the disadvantages described. A vibration meter in which a Hall voltage generator and a magnetic field are relative are movable to each other and the Hall voltage is used to map the movement, is characterized according to the invention that on a vibrating capable mass one Permanent magnet is arranged such that it is in the rest position of a stationary, parallel to the flux axis lying opposite Hall probe, so that the Hall voltage according to size and direction of deflection is proportional. Such a Hall probe can be between Soft iron or ferrite legs should be attached. It is advantageous to use the Hall probe as a thin plate or layer close to the face of the two ferrite pieces to be arranged in the air gap between them.

It is already known per se, a Hall voltage generator in one fixed magnetic field in such a way that its movements as changes the Hall voltage can be mapped.

Here, however, a Hall voltage also occurs in the rest position, so that you have to split the Hall voltage into DC and AC voltage components.

This is with the relatively low voltages and powers in the Hall circuit inexpedient.

The vibration meter according to the invention avoids this disadvantage, because the Hall voltage zero is easily obtained in the rest position. Also supplies the polarity of the Hall voltage indicates the direction of deflection. In the exploitable Range, the amplitude of the Hall voltage is also strictly proportional to the deflection amplitude.

A semiconductor body is particularly suitable as a Hall voltage generator from semiconducting compounds like the AIIIBv compounds, d. H. of fabrics, that of the III. and belong to Group V of the Periodic Table.

Such materials are e.g. B. indium antimonide and indium arsenide.

The invention is to be explained in more detail with reference to the drawing. While Fig. 1 shows an embodiment in its essential for the invention Parts illustrated in a greatly simplified representation, Fig. 2 shows the course of the Hall voltages generated depending on the deflection of the mass weight.

The mass weight 2 is suspended from a spring 1. A cushioning is not shown for the sake of simplicity of illustration.

The representation is also only illustrated for one direction of movement, while naturally at least three - z. B. mutually perpendicular - directions of movement are required to capture all motion components.

At the lower end of the weight 2 there is a permanent magnet 3, that protrudes beyond the weight.

The measuring probe is at a certain distance from the pole of the permanent magnet firmly attached. This consists of one located between two ferrite plates 4 and 5 Reverb plate. The semiconductor layer is perpendicular to the plane of the drawing by a control current passed through. The magnetic field affects the Hall generator, the device can be adjusted so that in the zero position, i.e. the starting position, the cancel magnetic fluxes. Only when it is deflected upwards or downwards Then a Hall voltage occurs, the magnitude and direction of which is a measure of the deflection and whose direction is.

In Fig. 2, the course of the Hall voltage is after deflections shown above and below from the zero position. With quasi-stationary deflection of the magnetogram is for small deflections in the working area between the lines 1 and II the Hall voltage is strictly proportional in its increase. In the event of a deflection of the magnet by 1 ttm, a Hall voltage of 1 mV, for example, is achieved. the Hall voltage can be amplified and, in a manner known per se, a registration make available. With the appropriate design of the resonance properties of the vibrating System, the movement of the ground is reproduced with an accurate amplitude in this method.

Claims (3)

PATENT CLAIMS: l. Vibration meter, especially seismograph, in which a Hall voltage generator and a magnetic field are movable relative to one another and the Hall voltage is used to map the movement, characterized in that that a permanent magnet (3) is arranged on an oscillating mass (2) in such a way that that it is in the rest position of a stationary Hall probe lying parallel to the river axis (4, 5) so that the Hall voltage according to the size and direction of the deflection is proportional. 2. Vibration meter according to claim 1, characterized in that that the Hall probe is located between soft iron or ferrite legs (4, 5) Semiconductor die is formed. 3. Vibration meter according to claim 2, characterized in that that the semiconductor body as a thin plate or layer close to the end face the soft iron or ferrite leg is arranged in the air gap between them. Documents considered: "Electronics", January 16, 1959, P. 63.