Electrical resistors – Mechanically variable – Deformable
Patent
1988-04-27
1990-09-18
Reynolds, Bruce A.
Electrical resistors
Mechanically variable
Deformable
338 92, 338 93, H01C 1010
Patent
active
049581384
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a resistive position indicator comprising an elongated resistive element having an electrical terminal at each end and a tap means which can be brought into contact with the resistive element. The contact point of the tap means divides the resistive element into two portions and is movable along the resistive element, so that the resistance ratio between the two portions of the resistive element can be varied within wide limits. The position indicator is primarily intended for use in motorized height adjusters for the pillar loop in vehicle safety belts but can also be used in many other devices, e.g. in electrical regulating and controlling equipment.
BACKGROUND ART
Resistive position indicators designed as slide rheostats and rotating potentiometers are previously well known. However, in these indicators a movable tap means is used which abuts against a normally coiled resistive wire or a resistive layer and is moved over the wire turns or the resistive layer when adjusted. This gives a comparatively high friction which causes a heavy wear and a reduced reliability and which also makes the adjustment of the indicator more difficult. Furthermore, these prior art indicators have a comparatively high weight and a compartively large required space.
SUMMARY OF THE INVENTION
The main object of the invention is to provide a resistive position indicator having a substantially lower friction when adjusted than the resistive position indicators of the prior art and also having an extremely low weight and a small required space. According to the invention, this object is achieved by giving the resistive position indicator the features set forth in the claims.
Due to the fact that the tap means comprises an elongated contact portion positioned in front of the resistive element and slightly spaced from this element, so that an air gap is formed between the resistive element and the contact portion of the tap means, and due to the fact that the air gap can be eliminated at any point along the resistive element by a compressive force, there is no means to be moved on the resistive element. This will reduce the friction substantially. Due to the fact that the compressive force can be applied on a flexible foil, only a small compressive force is required to provide the necessary contact between the resistive element and the contact portion of the tap means. Furthermore, the means providing the pressure can slide on the surface of the foil which can be made very smooth, so that the friction when the indicator is adjusted is further reduced. This is a substantial improvement over the resistive indicators of the prior art in which the contact portion of the tap means slides on a resistive surface having high friction.
Particularly, if both the resistive element and the contact portion of the tap means are applied on flexible foils, which can be made very thin, a very thin position indicator is obtained, which has a very small required space and which due to its flexibility easily can be positioned in narrow spaces. In this case, the indicator will also get a very low weight.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of a resistive position indicator according to the invention will now be further described below with reference to the accompanying drawings.
FIG. 1 shows a resistive position indicator, formed on a flexible foil strip, before the final assembly.
FIG. 2 is a cross section through the position indicator according to FIG. 1 after the final assembly.
FIG. 3 is a cross section through a height adjuster for the pillar loop in a vehicle safety belt, the height adjuster being provided with a resistive position indicator according to FIGS. 1 and 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The resistive position indicator shown in FIG. 1 comprises an elongated strip 10 of flexible plastic foil. The strip is divided into two portions 10B and 10C of substantially equal length by two notches 10A. The strip is further provided with an angularly pro
REFERENCES:
patent: 4314228 (1982-02-01), Eventoff
patent: 4479392 (1984-10-01), Froeb et al.
patent: 4489302 (1984-12-01), Eventoff
patent: 4651123 (1987-03-01), Zepp
patent: 4746894 (1988-05-01), Zeldman
patent: 4780701 (1988-10-01), Eppinger
Hawranek Jerzy
Jakobsson Karl P.
General Engineering (Netherlands) BV
Lateef Marvin M.
Reynolds Bruce A.
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