US2008745A - Modulated striking mechanism for electric alarm clocks - Google Patents

Description

July 23, 1935. E. L. CARLSON El AL MODULATED STRIKING MECHANISM FOR ELECTRIC ALARM CLOCKS Filed Jul 28, 1932 Patented July 23, 1935 UNITED STATES PATENT OFFICE MODULATED STRIKING MECHANISM FOR ELECTRIC ALARM CLOCKS Application July 28, 1932, Serial No. 625,228

.5 Claims.

In electric'alarm clocks the motors of which comprise a rotor anda stator magnet energized by alternating current, the hammers of the alarm sounding devices have, in some instances, been operated by the stator magnet by means of the magnetic impulses set up therein by the alternating current or by a supplemental magnet similarly energized. In such a mode of operation it has been found that the periodicity of movement of the hammer is so rapid that the sounding member responds thereto with a buzz or whirr rather than the clear ringing tone desired.

The primary object of the present invention is to provide, in clocks of this type, an alarm sounding arrangement by means of which this fault may be overcome.

To this end the invention consists in the provision of an alarm sounding member and means of such construction and arrangement for striking same in response to the magnetic impulses set up in the magnet which operates same that, although the magnet when energized by alternating current of commercial relatively high frequency, such as sixty-cycle, will impart a very rapid vibration to the striking means, the striking effect of same upon the sounding member will be so modified or modulated as to produce a clear ringing tone, all as will be explained hereinafter more fully and finally claimed.

In the accompanying drawing illustrating the invention, in the several figures of which like parts are similarly designated,

Fig. 1 is a back view of those parts of an electric alarm clock in which the structure of the invention is embodied, a portion thereof being broken away in the interest of clearness;

Fig. 2 is a side view of the parts illustrated in Fig.

' Fig. 3 is a. bottom view thereof;

Fig. 4 is a perspective view of the hammer of the alarm mechanism;

Fig. 5 is a view similar to Fig. 4 but showing a modification; and

Fig. 6 is an enlarged axial sectional elevation of the alarm sounding member and its mounting.

The clock, the motor and alarm sounding elements of which are illustrated in the drawing, is of the synchronous electric motor type, and

includes a suitable mounting plate I providingv bearings and supports for the rotor 2 and preferably laminated stator or field magnet 3 of the electric motor which drives the time train of the clock (not shown) by means of an appropriate pinion or the like 4. The stator magnet 3 is provided with coils 5, having terminals 6 attached to binding posts I which form a means for connecting the motor with a suitable source of alternating electric current through appropriate leads 8.

The back plate 9 (shown partially broken away in Fig. 1) which furnishes a protective covering or shield for the motor, and acts also as a bracing means for. the laminated stator magnet 3, is preferably formed with an integral support or bracket l0 having an offstanding portion H to which the alarm sounding member or bell I2 is attached in a novel manner presently to be described.

Although two forms of means for striking the alarm sounding member or hell 12 are shown in Figs. 1, 2, 3 and 4 and in Fig. 5, respectively, they are the same in the essential particulars whereby a clear ringing tone of the sounding member or bell I2 is obtained despite the rapid vibration imparted by the magnetic impulses set up in the operating magnet.

As shown in Figs. 1 to 4, inclusive, the striking mechanism comprises a hammer including a relatively rigid arm l3 so shaped as to form at one end a bearing portion l4 and an apertured attaching lug 15, both of which bear against the projecting end [6 of the stator magnet 3 and provide a means whereby the arm may be fixedly attached thereto by an adjacent clamping bolt I! of the plurality of same which serve to secure the plates comprising the laminations of the stator magnet 3 in lamellar arrangement. The arm I3 is provided intermediate its ends with an offset portion Is by which it may clear the adjacent coil 5 and its opposite end is is brought into proximity to the end portion 20 of the stator magnet 3 in position to be attracted thereby in response to magnetic impulses set up in the magnet as described.

Although the arm i3 is formed as a relatively rigid member, it has suflicient inherent resiliency to permit it to vibrate relatively to the stator magnet 3 and sounding member or bell [2, its portion adjacent to its attached end l4 serving as a flexing hinge.

Instead of providing a striking part or clapper rigid with the end IQ of the arm l3, as has heretofore been done, a resilient member, preferably in the form of a light spring leaf 2|, is riveted or otherwise rigidly fixed at one of its ends at a point adjacent to the end IQ of the arm l3 and carries at its other end a striker having a head 22 arranged adjacent to one face of the end IQ of the arm l3 and a shank 23 by which it is fastened to the member 2|, this shank extending through a recess 24 in the end of the arm. By this arrangement of parts it will be seen that the striker is resiliently mounted on the am l3 and is capable of free spring movement with respect thereto.

Instead of depending upon the flexing hinge action of the arm 53, as described, the portion i i-l5 thereof may be joined to the offset portion 58 by a hinge 25, Fig. 5, and the arm drawn to retracted position by a helical or other spring 26 connected with it and with a fixed part indicated at 27, a stop 28 being provided to limit the extent of its retraction.

It has been found, with a hammer thus constructed, that although the hammer advances to striking position and retreats therefrom in synchronism with the magnetic impulses set up in the stator magnet by the alternating current, the provision of the resiliently mounted striker, which is capable of striking movement relatively to the vibrating end H) of the arm, makes possible such desynchronization or modulation of the striking action asto result in elimination of the buzz or whirr objected to and the production of the desired clear ringing tone.

Again referring to the mounting of the sounding member or bell l2 hereinbefore mentioned, it has been found that the tone may be further improved by cushioning this mounting. To this end the sounding member or bell I2 is provided with an aperture 29 in which is arranged a cushioning member 33 of rubber or other relatively soft, yieldable material, preferably in the form of a grommet having portions 3i extending over and engaging the faces of the sounding member or bell I2, and provided with an axial opening 32 to receive a bolt 33 by means of which the cushioning member may be compressed and the sounding member or bell I2 relatively rigidly attached to the portion I I of the bracket or support ID.

The bracket or support it has been described as formed integral with the plate 9, but, obviously, it could be made as a separate member, or the sounding member or bell could be otherwise suitably supported.

Although the alarm sounding member and its modulated striking mechanism are hereinbefore particularly described as adapted to an electric alarm clock the stator magnet of the motor of which is utilized to impart striking movement to the hammer, it is to be understood that they may be incorporated in electric alarm clocks in which an auxiliary magnet energized by alternating current and distinct from the stator magnet is employed.

Various changes and modifications other than and in addition to those specifically referred to are considered to be within the spirit of the invention and the scope of the following claims.

We claim:

1. An electric alarm clock comprising: an alarm-sounding member, a magnet having spaced poles and designed and adapted to be energized by alternatin current of commercial frequency to set up therein magnetic impulses, and a hammer for said sounding-member including a relatively-rigid magnetic arm rigidly secured to one pole and extending to a second pole and having its end adjacent said second pole vibratable in synchronism with the alternating-current toward and away from said second pole in response to the magnetic impulses set up in said magnet, and a striker resiliently mounted upon said magnetic arm and designed and adapted to vibrate relatively thereto and to strike said sounding-member.

2. An electric alarm clock comprising: an alarm-sounding member, a magnet formed of laminations connected at spaced poles by bolts and designed and adapted to be energized by alternating current of commercial frequency to set up therein magnetic impulses, and a hammer for said sounding-member including a relativelyrigid magnetic arm mounted on one of said bolts at one of said poles and extending to a second pole and having its end adjacent said second pole vibratable toward and away from said second pole in response to the magnetic impulses set up in said magnet, and a striker mounted upon said magnetic arm to strike said sounding-member.

3. An electric alarm clock comprising: an alarm-sounding member, a magnet having spaced poles and adapted to be energized by alternating current of commercial frequency to set up therein magnetic impulses, and .a hammer for said sounding-member including a relatively-rigid magnetic arm rigidly secured to one pole and extending to a second pole and having its end adjacent said second pole vibratable toward and away from said second pole in response to the magnetic impulses set up in said magnet, the movable end of said arm being provided with an aperture; a resilient member carried by said arm adjacent to its vibratable end and extending adjacent to said aperture; and a striker having a head arranged adjacent to one face of said arm and a shank extending through said aperture and connected with said resilient member, said striker being designed to have vibratory movement desynchronized relatively to the vibratory movement of said arm and to strike said sounding-member in response to movement of said arm.

4. An electric alarm clock comprising: an alternating-current motor including a statormagnet formed of laminations connected at spaced poles by bolts and adapted to be energized by alternating current of commercial frequency; an alarmsounding member; and a hammer for said sounding-member adapted to have striking movement imparted to it by the statormagnet of said motor, said hammer including a relatively-rigid magnetic arm mounted on one of said bolts at one of said poles and extending to a second pole and having its end adjacent said second pole vibratable toward and away from said second pole in response to the magnetic im-' pulses set up in said stator-magnet, and a striker mounted upon said magnetic arm to strike said sounding-member.

5. An electric alarm clock comprising: an alternating-current motor including a statormagnet formed of laminations connected at spaced poles by bolts and adapted to be energized by alternating current of commercial frequency; an alarm-sounding member; and a hammer for said sounding-member adapted to have striking movementimparted to it by the stator-magnet of said motor, said hammer including a relatively-rigid magnetic arm mounted on one of said bolts at one of said poles and extending to a second pole and having its end adjacent said second pole vibratable toward and away from said second pole in response to the magnetic impulses set up in said stator-magnet, and a striker mounted upon said magnetic arm to strike said sounding-member.

ELOF L. CARLSON. ARTHUR B. POOLE.

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