DE1165291B - Electromechanical converter working according to the Hall effect - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN 4SiZTZW PATENT OFFICE Internat. KL: G Ol d

EDITORIAL

German KL: 42 d-1/12

Number:
File number:
Registration date:
Display day:

C 15811 IXb / 42 d
November 19, 1957
March 12, 1964

The invention relates to an electromechanical converter working according to the Hall effect, whose semiconductor element is movable relative to a magnetic field in such a way that a corresponding movement Output signal arises. This transducer contains a film of semiconductor material on which two the connecting terminals carrying areas of conductive material at a distance from each other with approximately parallel edges are arranged.

Electromechanical converters of this type can be found, for example, in pickups and microphones Use.

The characteristic of the invention is seen in a gap bridged with a semiconductor layer with a small gap width in relation to the gap length.

In a known electromechanical converter, the gap bridged with a semiconductor layer has a very large gap width in relation to the gap length. The subject of the invention is the field Constant over the gap length, while in the known construction it is integrated over the entire surface will.

For a better understanding, the invention is explained below using an exemplary embodiment will.

The drawing shows in

1 shows a schematic section through a transducer according to the invention and

FIG. 2 is a plan view of part of the transducer according to FIG. 1.

In the drawings, a converter operating with indium antimonide is shown. A movie 1 this Material is attached to a thin glass plate 2, which serves as a carrier. One sits stronger over the film as the indium antimonide conductive layer 3, for example silver, which according to FIG. 2 is a narrow one Leaves gap 4 on the antimonide layer extending over the entire width of the layer. The areas 5, 6 of the The electrodes are formed by a silver layer on both sides of this gap. A highly conductive material 7, for example Silver bronze, is applied to the silver electrodes and is used to connect the terminals or the like

If such a transducer element is used, for example, in a microphone or a pickup, then the glass carrier 2 is connected to a suitable membrane or a scanning needle in such a way that that he is moved in his plane.

A magnet system, preferably a permanent magnet, consisting of the poles 8 and 9, is used to generate a magnet system that works perpendicular to the plane of the indium anti-hand effect
electromechanical converter

Applicant:

Cosmocord Limited, Waltham Cross,

Hertfordshire (UK)

Representative:

Dipl.-Ing. R. H. Bahr and Dipl.-Phys. E. Betzier,

Patent attorneys, Herne, Freiligrathstr. 19th

Named as inventor:
Alberto Loro, Montreal (Canada),
George Victor Planner, Sunbury-on-Thames,
Middlesex (UK)

Claimed priority:
Great Britain 4 December 1956
(No. 37 008)

monid-layer standing magnetic field. Electric current is sent through the layer. Will the Layer set in motion by a movement of the membrane or the scanning needle and are thereby If magnetic field lines are cut, the resistance of the layer changes, and the current is as a result modulated in accordance with the deflections of the membrane or the stylus. A number of difficulties arise in manufacturing a transducer of the type described above on. In the first place, an extremely thin film of the active material must be made so that it has the highest possible electrical resistance. In contrast, in the case of indium antimonide, which is particularly preferable in this regard because of its highly effective properties, the The conductivity of the material is very high. In practice, however, it is inconvenient to use a converter with a to choose a very low resistance, since low voltages and high currents are required for its operation required are.

To produce the thin indium antimonide layer, a slitting knife is used, for example cut a strip from a block. The strip should initially be as thin as practically possible be. This strip is attached to a workpiece holder and one surface is then machined for so long until it is plan. The strip is then

409 538/231

rotated and the machined surface attached to the glass plate forming the carrier. Now the other surface of the material is processed in the same way. This process makes it possible to produce a layer that is only a few μ thick.

Of course, other processes for the production of very thin layers can also be used, For example, vacuum deposition, brushing, evaporation from a solvent od. The like. For example, a recess of very shallow depth can be etched out in the glass carrier. The antimonide is then poured into this recess under pressure using a cover plate and then processed the exposed surface.

In addition, the indium antimonide layer should be relatively short in order to achieve a maximum Hall effect Direction of the current flow and be comparatively large perpendicular to the current flow and the magnetic field. Furthermore, it may be desirable to make the dimensions small in the direction of the current flow, in particular, when the element is subjected to small displacements with respect to the magnetic field target. This requirement is met that the silver or similar cover layer with a Provides a thin gap, for the production of which various methods are possible. The most comfortable at the moment The process consists in applying the silver by depositing it under vacuum and thereby creating a Use fine wire as a mask to prevent precipitation where the gap will arise target. This method is simple and effective and gives a well-defined column of precisely determinable width.

Good results can also be achieved by first using the entire surface of the layer Silver coats, deposits a photosensitive etching base on the silver layer, closing the etching base developed a suitable image and then with the help of an etchant for silver, but not for the antimonide removed the silver at the places intended for the gap.

Another method of making a narrow gap is to first place an antimonide layer and then apply a thin line of bituminous paint to the layer where the Gap should arise. The surface is then plated with copper by electroplating. The color prevents the precipitation of copper on the underlying indium antimonide, so that after an unplated gap remains after the paint is removed.

It has been found that with this method, precise gaps 0.3 mm wide in the direction of flow can be measured and manufactured from a few millimeters wide.

In a modified embodiment of the converter according to the invention, the resistance is increased by splitting the indium antimonide in the gap into a number of separate parts, so that several Gaps of smaller length arise. The current is forced to alternate over the length of the column flow. This modification is obtained in an extremely simple manner by adding the antimonide layer through a series of slots, as at 10, 11 and 12 in Fig. 2 indicated, removed, the slots alternating from opposite ends of the transducer element extend parallel to the direction of flow in the gap and in each case transversely to the gap. In this way the two electrodes are cut through the slots to form a current path, each through leads to a number of contiguous columns. One made individually in this way Slot leads to a substantial increase in resistance, for example a four-fold increase, because the gap resistance is doubled and the two gaps are in series.

ίο A gap of the specified dimensions at the The layer thickness also specified gives a resistance in the order of magnitude of 10 to 100 ohms a change in the magnetic field from 0 to 10,000 Gauss.

These numbers can be obtained by splitting the gap, as described above, increase significantly. The slots in the antimonide can be made mechanically, for example by means of a slot spring Cutting or grinding tools, which the antimonide layer and the silver layer as well as the silver bronze layer remove, or use a chemical process similar to that described above Procedure. In this case, however, an etchant is used that acts on both antimonides and the silver layer appeals to. Applying the plating methods described above, then plating can be prevented at the points where the slots are to be created by working in a similar manner Wisely applies color. For reasons of strength, the carrier is preferably not cut. Of course, instead of a single indium antimonide layer, something more complicated can also be used Use systems with multiple layers. The magnet system for the production of the magnetic field, in which the transducer element moves, can be from a simple one equipped with suitable pole pieces Permanent magnets of high permeability exist that leave an air gap free. However, since the Effectiveness of the transducer on the change in the field strength to which the semiconductor material is subjected is tuned, it is desirable that the magnet system provides a field structure which has a has the greatest possible change in the field strength with even small movements. Hence it is in many Cases advantageous to use a plurality of pole pieces on the magnet or magnets and such the To change the field structure. The field in which the material moves should be as strong as possible, because at As the strength of the magnetic field increases, the resistance of the material becomes higher.

In the converter described, the element carrying the current is moved in the magnetic field. this however, it is not the only possible way. For example, it is possible for the element generating the magnetic field to move in relation to the current-carrying element move or otherwise change the field strength. The field strength can be changed by changing a electromagnetic current change, but such an arrangement is in their application limited. Since the Hall effect is a function of the magnetic field, the converter can also be used in general Use as a gauge or control device that responds to field changes. The converter can so it can also be used for magnetic and similar experiments.

Claims (3)

Patent claims: 1. Electromechanical transducer working according to the Hall effect, its semiconductor element is movable relative to a magnetic field in such a way that an output signal corresponding to the movement arises, with a film of semiconductor material on which two the connecting terminals load-bearing areas made of conductive material at a distance from one another with approximately parallel ones Edges are arranged, marked by a gap bridged with a semiconductor layer with a ratio to the gap length small gap width. 2. Converter according to claim 1, characterized in that it extends approximately perpendicular to the gap at least one of the areas has a slot which divides this area into partial areas. 3. Converter according to claim 1 and 2, characterized in that the gap by covering the semiconductor layer with a line-shaped mask before the application of the conductive areas forming material is made. Considered publications:
ίο German Patent No. 590 678; German patent application S 38725 Villa / 21a ² (published on September 6, 1956);
U.S. Patent No. 2,562,120. 1 sheet of drawings 409 538/231 3.64 © Bundesdruckerei Berlin