GB1304431A - - Google Patents

Abstract

1304431 Variable resistors NIPPON KOGAKU KK 17 Feb 1970 [19 Feb 1969(2)] 7543/70 Headings H1N and HIS A variable resistor comprising a resilient contact member 2, 4 movable in a unidirectional curved path over a planar base disk 12 containing resistive elements 12b, 12e and biased, by means of the resilience of the contact wires 4 or an external spring member (16, Fig. 15, not shown), against a second smaller disk 13 which guides the path of the brush over the resistive elements and an adjustable arrangement 17, 19, 20 to provide a short circuit path outside the desired resistive range. In Fig. 2, the brush guide disk 13 (nylon with molybdenum dioxide) is positioned on the resistance disk using the marks 12 i , 12h (deposited with the resistive areas for accuracy) and leading edge 12c of the resistive area 12b for location, the edge 13c of the guide disk being adjusted to give the correct contact path for the contact wires 4 and then secured with adhesive via holes 13b. The metal support disc 11, terminal 18, and the short circuiting disks 20, 19, are added and held in place by the insulating collar 10. The tongue 18a of the metal ring 18 projects through the slot 13d making ajustable contact with the terminal resistance area 12f. Electrical contact between the base 11 and 19, 20 is effected by the area 11a. The short circuit discs are set at the required separation angle 0 (Fig. 4) and the assembled metal brush supporting disk arrangement 1, 2, 4, 17, fitted around the collar 10. The brush wires 4 which would naturally be at position 7 (Fig. 3) are pushed outwards by the guide disk edge to take up position 8 (Fig. 3) the sprung member 2a (Fig. 1) biasing the wires on the resistance track. The brush support member is rotated relative to the rest of the resistor by an external driving means (not shown). In operation within the resistance range, i.e. a rotation of # degrees between positions A and B (Fig. 4) the circuit is established by 1-2-4-12b-12f-18-20-11; the short circuit contact 17a being disconnected from 19 and 20 while when outside the required resistive range the contact 17a rides on 19 or 20 and short circuits the resistive circuit by a parallel circuit 1-17-19 or 20-11. The resistance element 12b is a tapered solid form and in continuation of its leading end 12c and upon a tap portion 12a is a second tapered resistive layer 12e which has a resistance per unit area higher than 12b. Further embodiments are described (Fig. 6-15, not shown) involving modified shorting circuits and double layer guide disks, a variable resistor assembly without the shorting and the external sprung contact member. The circumferencial shape of the guide disk may be altered to give a specific resistance path.