US2308863A - Variable impedance - Google Patents

Description

Jan. 19, 1943. H. J. CRAYMER 2,308,863

VARIABLE IMPEDANCE Fil ed Jan. 27; 1940 VAN/4 INVENTOR. HF/VP Y Jflmf' CF14 V0715 Q BY #5 ATTORNEY.

Patented Jan. 19, 1943 UNITED VARIABLE IIVIPEDANCE Henry James Craymer, Chelmsford, England, assignor to Radio Corporation of America, a corporation of Delaware Application January 27, 1940, Serial N0. 315,887 In Great Britain March 7, 1939 8 Claims.

This invention relates to variable impedance elements such as, for example, variable inductances and resistances. As applied to variable inductances, the primary, though not the exclusive application of the invention, is to the provision of improved variable in-ductance suitable for use in a high frequency generator required to cover a Wide range of frequency and for similar purposes. As applied to variable resistances, the invention is of quite general application.

The simplest form of variable inductance at present commonly used in a wide range high frequency generator consists of a coil and means for disconnecting or short-circuiting conductor turns in said coil for varying the inductance. This type of arrangement has the defect that as the inductance decreases the current increases and the resultant increase in heating imposes a serious limitation. Another arrangement which is sometimes used comprises a number of conductor turns associated with links or external switches whereby the separate conductor turns may be connected in series or parallel or seriesparallel to vary the inductance. This type of arrangement, though avoiding the defect of excessive heating, above referred to, presents the defects (1) that if external connection links are used it is a comparatively slow matter to change inductances, while, if external switches are used,

this greatly increases complication, and (2) provision is made only for combinations of complete conductor turns so that only a limited number of inductance values is obtainable and the inductance is not continuously variable.

The present invention as applied to inductances, seeks to avoid the above defects.

According to this invention, a variable inductance or resistance device comprises a plurality of open rings which result in electrical interrupted conductor turns positioned adjacent one another, each ring carrying contact means located at the open point whereby it makes electrical connection with its neighbor or neighbors, said ring or conductor turns being individually movably mounted with respect to one another, and the whole arrangement being such that by adjusting the relative positions of the rings the points at which they contact with one another may be varied and the inductance or resistance (as the case may be) of the whole device thereby continuously varied from a condition in which the resultant conductor turns are effectively in series to a condition in which turns are effectively in parallel.

The invention is illustrated in the accompanying drawing. For convenience of reference, the figures are numbered 1a, 1b, 1c, 2, 3a and 3b. Figures la, 1b, 1c illustrate in simplified form one embodiment in three positions of adjustment, while Figure 2 shows a modification, and Figures 3a and 3b illustrate a further modification.

Referring to Figures 1a, lb, 10, the coil therein illustrated comprises tWo open-ended rings-any number of rings might be used but only two are shown for the sake of simplicity-A and B being terminals of one ring, and C and D the terminals of the other. At A is a projecting contact member X which makes sliding contact on the adacent ring near C, while on the said adjacent ring at D is a similar contact device Y. which contacts with the first ring near B. The rings are coaxially mounted and individually rotatable with respect to one another about the common axis. One terminal of the whole coil is at B, while the other terminal is at C, connection to C being made by means of a further contact device Z which slides on a fixed plate (not shown). Obviously, both rings need not be rotatable for relative movement is all that is required; thus, the ring A, B, may be fixed and the turn C, D, rotatable. In Fig. 1a the two rings are connected together in parallel; in Figure 10 they are in series. Fig. 1b shows one of the infinite number of intermediate adjustments obtainable between these two extreme values.

In view of the description already given, Fig. will be found largely self-explanatory, this figure showing a three-conductor arrangement consisting of interrupted rings AB, CD, and EF. Obviously, in Fig. 2 one of the rings, preferably the intermediate ring CD may be fixed and the other two individually rotatable.

The contact devices illustrated are given only by way of example; for example, the rings, themselves, may be arranged to be brought into contact over portions that are in parallel in which case no projecting contact devices will be necessary. Furthermore, the turns may be in the form of flat interrupted annuli spaced apart by discs of insulating material, the whole being mounted on a common axial member of insulating material. This makes a very strong compact structure. Again, by making the turns of required resistance material any of the embodiments described may be utilized as Variable resistances.

In some cases where only occasional adjustment is required, the sliding contacts can be replaced by clamps, still retaining the same principles. Such a case is shown in Figs. 3a, 3b, wherein 3a is a section and 311 an end view. Two coil assemblies are shown linked together by a link L and turns of one of the assembli s are shown connected by clamps V.

Obviously, variable inductance or resistance devices in accordance with this invention may be incorporated with known switch or link type variable inductances or resistances-for example, in cases in which it is required to obtain a series of steps of inductance or resistance with continuous variation between the steps.

What is claimed is:

l. A variable impedance device comprising a plurality of fixed and movable open rings of conductive material, said fixed and movable rings alternately positioned coaxially in a row with a space between each fixed and movable ring, a contact member secured to each ring and contacting an adjacent ring and so located in the space between a fixed and movable ring that a sliclin contact is made to an adjacent ring when a movable ring is rotated with respect to a ixed ring.

2. A variable impedance device comprising a plurality of fixed and movable open rings of conductive material positioned coaxially and alternately in a row with a space between each fixed and movable ring, a wedge-shaped contact member located in said space and secured to one end of each ring, said wedge-shaped contact member having its pointed end projecting in a direction toward an adjacent ring, said movable rings arranged to contact and rotate relative to said fixed rings so that the pointed end of said contact member makes sliding contact with an adjacent ring to vary said impedance device.

3. A variable impedance device comprising a plurality of fixed and movable open rings of conductive material, said fixed and movable rings alternately positioned in a row with a space between each fixed and movable ring, each ring being of the same diameter and coaxially mounted with respect to an adjacent ring, a contact member carried by each ring and located within the space between a fixed and movable ring near the open ends thereof for making a variable sliding contact with an adjacent ring and for electrically connecting said rings together in parallel, Whereby the impedance of said device is continuously Varied.

4. A variable impedance device comprising a plurality of fixed and movable open rings of conductive material, said fixed and movable rings alternately positioned in a row with a space between each fixed and movable ring, each ring being of Iii) the same diameter and coaxially mounted with respect to an adjacent ring, a contact member carried by each ring and located within the space between a fixed and movable ring near the open ends thereof for making a variable sliding contact with an adjacent ring and for electrically connecting said rings together in series, whereby the impedance of said device is continuously varied.

5. A variable inductance device comprising a plurality of fixed and movable open rings of conductive material, said fixed and movable rings alternately positioned in a row with a space between each fixed and movable ring, each ring being of the same diameter and coaxially mounted with respect to an adjacent ring, a contact member carried by each ring and located within the space between a fixed and movable ring near the open ends thereof for making a variable sliding contact with an adjacent ring and for electrically connecting said rings together in parallel, whereby the inductance of said device is continuously varied.

6. A variable impedance device comprising a plurality of open rings of conductive material having internal electrical reactance, some of said rings being fixed and some movable with respect to each other and alternately positioned with a space between, contact means positioned within said space and secured to each on of said rings, said contact means arranged to make electrical connection to an adjacent ring, said movable rings being individually mounted about a common axis with respect to an adjacent fixed ring so that the movable rings make a sliding contact with said fixed rings to continuously vary the impedance of said device.

'7. A device as claimed in claim 6 wherein the rings of conductive material are mounted coaxially and are of the same diameter, said movable rings being adapted to be rotated about the common axis with respect to an adjacent fixed ring, said contact means being adapted to make a sliding contact with at least one adjacent ring.

8. A variable impedance device comprising two groups of coils, each group including a plurality of fixed and movable open rings of conductive material, said fixed and movable rings alternately positioned in a row about a common axis with a space between each fixed and movable ring, a clamp member arranged to bridge over said space to contact two adjacent rings and means to vary said device by changing the position of some of said movable rings with respect to said fixed rings. 1

HENRY JAMES CRAYMER.

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