US1582770A - Adjustment for the magnets in telephone receivers and the like - Google Patents

Description

April 27 1926.

A. H. MIDGLEY ADJUSTMENT FOR THE MAGNETS IN TELEPHONE RECEIVERS AND THE LIKE Filed August 25 1925 Patented 7 Apr. 27, 1926.

UNITED? STATES ALBERT HENRY MIDGLEY -OF uxnnreen, ENGLAND.

ADJUSTMENT FOR THE'MAGNE T S IN TELEPHONEiREGEIVERSAND THE LIKE.-

Application filed Ai1gust-25, 1925. Serial N0. 52,432.

To all'wlwmz't may concern. I 7 I Be it known that I, ALBERT HENRY MIDG- LEY, a subject of the King of Great. Britain,

residing at F airfield, Hareiield Road; UX

bridge, in thecounty 01 Middlesex, England,

have invented certain new and useful Improvements in and Connected with Adjustments for the Magnets in Telephone Receivers and the like, of which the following is a specification. i

This invention comprises improvementsin and connected with adjustments for the magnets of telephone receiver's, loud speakers and the like and is concerned with, arrangements in which the permanent-magnet is supported by pivots about which it is adjusted bymeaus such as a screw forgiving an accurate adjustment of the pole tipsin relation to'the vibratory diaphragmor the like. In known arrangements the pole pieces have been carried at the freev ends oflimbs of a horse-shoe magnet supported pivotally at the opposite ends oi" the'limbs. In such arrangements the flux between the pole tips was parallel with the'pivotal axis. l/Vhen the 'faees'of the pole tips are parallel with the diaphragm there is a magnetic flux which'is'unitorm over the'faces of the pole tips and the opposed portions oi. the diaphragm but when'the magnet is pivotally adjusted so that the said faces are no longer parallel with the diaphragm but inclined thereto; a crowding of the lines offorce takes place in those portions of the pole faces which lie nearer. to the diaphragm than others. In this way the incidence and the distribution of the magnetic flux is altered in performing the pivotal adjustment.

Now according to this invention, a pivotally supported telephone magnet structure has the pole pieces disposed in such a man- 'ner that the direction of the flu); is at right angles to the pivotal axis and in the direction of the length ofthe magnet. With such an arrangement, the distribution of the flux remains about the same in spite of the fact that in the pivotal adjustment of the mag net, that pole piece which is farther from the pivot moves over a greater distance than the pole piece which is nearer to the pivot.

In order to enable the invention" to be readilyunderstood, reference isinade to the accompanying drawing illustrating one suitable construction in accordance with these improvements in which drawings vibratory diaphragm Z) in operative relation with magnet poles c, the diaphragm I) being coveredby a cap or cover (Z provided with'a snigot, c for'the fitting on of ahorn or trumpet (not shown). which maybe of any suitable form.

The magnet structure comprises a pair of permanent bar magnets m whichare braced apart by stout yoke pieces n it these bars and y'olres be'ingheld' strongly together by means of bolts andnuts at'0 aud o, The pole pieces 0" are seci'ir'ed against; the inner ends of the yokes n n by wedging means p which'are not further described herein as they form no part of this invention but are fully described and claimed in my patent application of even date. The magnet structure possesses strength and rigidity suiting'it for thepivotal mounting now described; Also it will be seen that the yokes 41,42 are spaced apart-inthe length direction of the magnet structure.

At one end of the structure, the bar magnets are' fitted with centre point bearings. For'example, the ends of the belt at 0 may be formed .with conical depressions or centres which are adapted for being engaged by centre point screws 9 screwed into the cast framing 1" secured within the base a, these screws q being adjusted so that their points engage pivotally with the centre point F'gure l is a central vertical section of bearing recesses aforesaid. The yoke piece n is prolonged beyond the ends of the bar magnets m and such prolongation .9 may be of reduced thickness as shown. The prolongation s extends beneath a part of the casting 1 and rests upon a bow or blade spring t this spring being supported by adjustable nuts u screwing on screws '0 inserted from above through holes in the cover (Z and casting r. The spring t is slotted where it takes over the screws '0 as shown in'Figure 3, in order that it may be free to flex under different degrees of, adjustment pressure. An adjusting screw to provided with a milled head is screwed down through the casting 1" and so as to bear upon the top surface of the prolongation s of the yoke piece it. By screwing down the screw w the magnet structure is depressed about its pivots Q against the resistance of the spring t and the pole tips 0 are adjusted away from the diaphragm or the like. Upon unscrewing the screw to the spring t or other resilient support elevates the magnet structure about the pivots g and the pole tips are adjusted towards the diaphragm Z), as will be readily understood.

Referring to Figure 1, it will be seen that when the screw 10 is screwed down to depress the right hand end of the magnet structure, the gap between the tip of the right hand pole piece a and the diaphragm will be increased to a greater extent than the gap between the tip oftheleft hand pole piece 0 and the diaphragm. However, it will be apparent that such alteration of the gaps will simply increase the reluctance of the magnetic circuit without substantially altering the distribution of the lines of force flowing through the diaphragm.

The casting" 1" may be a die casting in aluminum alloy or the like secured down upon the base a principally by means of screw and nuts w. The milled head of the adjusting screw to being situated at the top and at the periphery of the cover cl, it is very conveniently situated for instant operation and the adjustments can therefore be performed with much greater nicety and freedom tha-n'is possible when the head of the adjusting screw is situated beneath the base or at the back of a loud speaker. Furthermore, the terminals y, y for the magnet coils may be on the top of the cover cl so as to be readily accessible,as will be apparent from the drawing.

The hereinbefore described magnet structure is not the only suitable structure for the purpose of this invention, andthe means for pivotally mounting and adjusting it can be varied without departing from these improvements.

I claim 1. Telephonic receiver comprising an elongated magnet structure, a pivot axis for said structure at one end thereof; pole pieces secured in said structure at about the middle of its length and arranged one behind the other along a line perpendicular to the pivot axis, and adjusting means operative directly upon the free end of the structure to adjust the latter about said axis.

2. Telephonic receiver comprising an adjustable magnet structure composed of parallel barmagnets, yoke pieces spacing said bar magnets and pole pieces secured between said yoke pieces and against the inner ends thereof. 7 7 f 3. Telephone receiver. comprising a magnet structure composed of parallel bar magnets and yoke pieces inserted as spacers between the end portions of said bar magnets,

transverse securing bolts bolting together said bar magnets and yoke pieces, one of said bolts being adapted as an antifriction pivot bearing, and pole pieces secured against the inner ends of respective yoke pieces substantially asset fort i 4. Telephone magnet structure comprising a frame having permanent bar magnets for its longitudinal side members and yoke pieces spa-cingsaid bar magnets for its end members, polar formations on the inner ends of the yoke pieces, and pole pieces perpendicular to the plane of said frame and secured against respective polar formations.

5. Telephone receiver comprising a magnet structure composed of parallel bar magnets spaced apart by yoke pieces disposed between the end port-ions of said bar mag nets, a pivotal support for one end of said structure, a resilient support for the opposite end of saidstructure, mechanical adjusting means operative in opposition to said resilient means, and pole pieces secured in said structure against the inner ends of respective yoke pieces. v

6. Telephone receiver comprising a magnet structure composed of parallel bar mag nets spaced apart by yoke piecesdisposed between end portions of said bar magnets, a pivot support for one end of said structure, an adjustable spring support for the opposite end of said structure, mechanical adjusting means operative upon said structure in opposition to said spring, and pole pieces secured in said structure in contact with respective yoke pieces substantially as set fortl.

7. Telephone receiver comprising a magnet structure composed of parallel bar magnets spaced apart by yoke pieces disposed between end portions of said bar magnets, a pivot support for one end of said structure, a bow spring engaging beneath the opposite end of said structure, adjustable supports for the ends ofv said bow spring, an adjusting screw operable from above and acting downwardly on said structure against the resistance of saidspring, and pole pieces secured in said structure in contact with re spective yoke pieces substantially as set forth.

8. In atelephone receiver a robust magnet structure comprising permanent bar magnets as longitudinal side members and yoke pieces inserted as spacers between end portions of said bar magnets. said bar magnets and yoke pieces being strongly bolted together, pole pieces in longitudinal align- 10 the opposite end of said frame, substantially as set forth.

ALBERT HENRY MIDGLEY.

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