GB1559626A - Variable resistor - Google Patents

Description

(54) VARIABLE RESISTOR (71) We, ALLEN-BRADLEY ELECTRONICS LIMITE, of Pilgrimsway, Bede Industrial Estate, Tyne and Wear, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the follow- ing statement :- This invention relates to variable resistors and is concerned particularly with a form of variable resistor in which an arcuate resistor is applied on a substrate which forms part of a housing for a rotor carrying a wiper contacting the resistor, the rotor being rotated by a worm and gear arrangement. This form of variable resistor will be referred to as being of the class specified. Such resistors may be used as trimmer potentiometers and are usually of small dimensions.

There is now provided a form of variable resistor of the class specified, wherein the rotary wiper carrier is of a thermoplastic material or an elastomer, e. g. nylon or rubber, has as an integral part of it the gear teeth to mesh with the worm and also stops for limiting the extent of rotation of the carrier, and has on its surface facing away from the substrate a series of pips which in assembly are resiliently compressed. The resilience in the gear teeth reduces the possibility of damage to the resistor by continued rotation of the worm after the stops on the carrier and housing come into contact, and the compressed pips eliminate tilt of the carrier.

A form of variable resistor of the class specified which incorporates the above and other features of technical importance is shown on the accompanying drawings in which :- Fig. I is a partially sectioned view of the resistor, Fig. 2 is an axial view of the wiper carrier, and Fig. 3 is a section through the carrier.

The resistor comprises a housing 10, conveniently of moulded plastics material, having centrally of the bottom of its cavity means limiting lateral movement of a wiper carrier 12, conveniently a moulded-in stub spindle 1 I for the wiper carrier 12. The housing also has a recess accomodating a worm 13 whereof, as is known for this specified class of variable resistor, the spindle is accessible from outside the housing 10 to allow the worm 13 to be rotated for adjusting the resistance.

The housing is closed by a substrate 14 which has applied to its surface facing the bottom of the housing cavity an arcuate resistor on which rubs a resilient wiper contact mounted on the carrier 12.

The carrier 12 is moulded from a resilient plastics material and has formed in one with it the worm wheel teeth 16 which are to cooperate with the worm 13, and also has radially-projecting shoulders 17 which cooperate with a stop 10a in the housing 10 to limit rotation of the carrier to less than 360 .

The carrier 12 is formed on its surface facing away from the substrate 14 with a series, conveniently three, of pyramidal pips 18 which on assembly of the resistor are resiliently compressed; the arrangement serves to eliminate tilt of the carrier during adjustment of the resistance.

The carrier 12 also has in it adjacent the worm wheel teeth 16 an annular groove 20 so that the teeth 16 are on the periphery of a radially thin rib 21 capable of localised flexing for example on overwinding when the stops 17,1 Oa abut.

Terminals 19 are provided at appropriate locations.

WHAT WE CLAIM IS :- 1. A variable resistor of the class specified wherein the rotary wiper carrier is of a thermoplastic material or an elastomer, has as an integral part of it the gear teeth to mesh with the worm and also stops for limiting the extent of rotation of the carrier, and has on its surface facing away from the substrate a series of pips which in assembly are resiliently compressed and which eliminate tilt of the carrier.

2. A variable resistor as claimed in claim 1, wherein the carrier is of nylon or rubber.

3. A variable resistor as claimed in claim 1 or claim 2 wherein the gear teeth are formed

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   (54) VARIABLE RESISTOR (71) We, ALLEN-BRADLEY ELECTRONICS LIMITE, of Pilgrimsway, Bede Industrial Estate, Tyne and Wear, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the follow- ing statement :- This invention relates to variable resistors and is concerned particularly with a form of variable resistor in which an arcuate resistor is applied on a substrate which forms part of a housing for a rotor carrying a wiper contacting the resistor, the rotor being rotated by a worm and gear arrangement. This form of variable resistor will be referred to as being of the class specified. Such resistors may be used as trimmer potentiometers and are usually of small dimensions.

   There is now provided a form of variable resistor of the class specified, wherein the rotary wiper carrier is of a thermoplastic material or an elastomer, e. g. nylon or rubber, has as an integral part of it the gear teeth to mesh with the worm and also stops for limiting the extent of rotation of the carrier, and has on its surface facing away from the substrate a series of pips which in assembly are resiliently compressed. The resilience in the gear teeth reduces the possibility of damage to the resistor by continued rotation of the worm after the stops on the carrier and housing come into contact, and the compressed pips eliminate tilt of the carrier.

   A form of variable resistor of the class specified which incorporates the above and other features of technical importance is shown on the accompanying drawings in which :- Fig. I is a partially sectioned view of the resistor, Fig. 2 is an axial view of the wiper carrier, and Fig. 3 is a section through the carrier.

   The resistor comprises a housing 10, conveniently of moulded plastics material, having centrally of the bottom of its cavity means limiting lateral movement of a wiper carrier 12, conveniently a moulded-in stub spindle 1 I for the wiper carrier 12. The housing also has a recess accomodating a worm 13 whereof, as is known for this specified class of variable resistor, the spindle is accessible from outside the housing 10 to allow the worm 13 to be rotated for adjusting the resistance.

   The housing is closed by a substrate 14 which has applied to its surface facing the bottom of the housing cavity an arcuate resistor on which rubs a resilient wiper contact mounted on the carrier 12.

   The carrier 12 is moulded from a resilient plastics material and has formed in one with it the worm wheel teeth 16 which are to cooperate with the worm 13, and also has radially-projecting shoulders 17 which cooperate with a stop 10a in the housing 10 to limit rotation of the carrier to less than 360 .

   The carrier 12 is formed on its surface facing away from the substrate 14 with a series, conveniently three, of pyramidal pips 18 which on assembly of the resistor are resiliently compressed; the arrangement serves to eliminate tilt of the carrier during adjustment of the resistance.

   The carrier 12 also has in it adjacent the worm wheel teeth 16 an annular groove 20 so that the teeth 16 are on the periphery of a radially thin rib 21 capable of localised flexing for example on overwinding when the stops 17,1 Oa abut.

   Terminals 19 are provided at appropriate locations.

   WHAT WE CLAIM IS :- 1. A variable resistor of the class specified wherein the rotary wiper carrier is of a thermoplastic material or an elastomer, has as an integral part of it the gear teeth to mesh with the worm and also stops for limiting the extent of rotation of the carrier, and has on its surface facing away from the substrate a series of pips which in assembly are resiliently compressed and which eliminate tilt of the carrier.
2. 2. A variable resistor as claimed in claim 1, wherein the carrier is of nylon or rubber.
3. 3. A variable resistor as claimed in claim 1 or claim 2 wherein the gear teeth are formed peripherally of the carrier and there is an , annular groove in the carrier so as to leave 'the teeth on a radially thin rib.
4. 4. A variable resistor of the class specified and substantially as herein described with reference to and as. shown in the accompany ing drawings.