US3662538A

US3662538A - Device for measuring repetitive identical time intervals

Info

Publication number: US3662538A
Application number: US115988A
Authority: US
Inventors: Rudolf Wittner
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-02-19
Filing date: 1971-02-17
Publication date: 1972-05-16
Anticipated expiration: 1989-05-16
Also published as: DE2007680C3; FR2080599A1; GB1343047A; FR2080599B1; CS164287B2; CH1052170A4; JPS5149229B1; DE2007680A1; DE2007680B2; CH526156A

Abstract

A shaft is journalled in a housing for turning movement about an axis; the shaft has a first portion and a second portion. A pendulum is fast with the first portion elongated radially of the axis for swinging movement about the same and a pair of anchor plates are mounted on the second portion axially spaced in parallel planes. The blades each have a first surface both of which face in one axial direction and a second surface which both face in the opposite axial direction. Each of the first surfaces is inclined to and has an edge portion which extends at least substantially radially of the axis and is convexly curved on a small radius in direction axially of the shaft towards the respectively associated second surface. A circumferentially toothed wheel is mounted and biased for rotation in a plane at least substantially normal to the planes of the anchor plates and parallels the axis so that consecutive teeth of the wheel engage first one of the first surfaces to slide along the same to and over the edge portion past the associated second surface while concomitantly imparting to the plates and thereby to the pendulum a swinging pulse and to subsequently abut against the other of the first surfaces where it again slides past the edge portion and second surface while the next-following tooth engages the first-mentioned first surface.

Description

United States Patent Wittner 51 May 16, 1972 [54] DEVICE FOR MEASURING REPETITIVE IDENTICAL TIME INTERVALS Rudolf Wittner, Johnstrasse 6, lsny, Allgau, Germany 221 Filed: Feb. 17, 1971 211 Appl.No.: 115,988

[72] Inventor:

Primary Examiner Richard B. Wilkinson Assistant ExaminerStanley A. Wal Attorney-Michael S. Striker [57] ABSTRACT A shaft is joumalled in a housing for turning movement about an axis; the shaft has a first portion and a second portion. A pendulum is fast with the first portion elongated radially of the axis for swinging movement about the same and a pair of anchor plates are mounted on the second portion axially spaced in parallel planes. The blades each have a first surface both of which face in one axial direction and a second surface which both face in the opposite axial direction. Each of the first surfaces is inclined to and has an edge portion which extends at least substantially radially of the axis and is convexly curved on a small radius in direction axially of the shaft towards the respectively associated second surface. A circumferentially toothed wheel is mounted and biased for rotation in a plane at least substantially nonnal to the planes of the anchor plates and parallels the axis so that consecutive teeth of the wheel engage first one of the first surfaces to slide along the same to and over the edge portion past the associated second surface while concomitantly imparting to the plates and thereby to the pendulum a swinging pulse and to subsequently abut against the other of the first surfaces where it again slides past the edge portion and second surface while the next-following tooth engages the first-mentioned first surface.

35 Claims, 16 Drawing Figures Ill/ll,

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DEVICE FOR MEASURING REPETITIVE IDENTICAL TIME INTERVALS BACKGROUND OF THE INVENTION The present invention relates generally to a device for measuring repetitive identical time intervals, and particularly to such a device which is usable with great advantage but not exclusivelyfor measuring time intervals in musical and medical use.

Devices of the general type in question are already well known and are used primarily in musical applications where they are known as metronomes. inasmuch as the use of the term metronome is thought to facilitate discussion and explanation of the present invention, this term will be employed hereafter to designate the device according to the present invention. I wish it to be expressly understood, however, that the use of this terminology is not intended nor to be construed as limiting the scope of the present invention to a device for musical purposes. Instead, the use of this term is for purposes of convenience only so as to facilitate explanation of the invention.

The known metronomes are, generally speaking, satisfactory in their operation. In other words, they fulfill their intended purpose. However, they suffer from the drawback that they are of comparatively large dimensions and thus are not readily transportable in the sense which is desired. This does not mean that known metronomes are large in an absolute sense; however, they are too large to be for instance readily accommodated in an instrument case or in the pocket of a garment, for instance a lab coat or a doctor's white gown or the like. Of course, attempts have already been made to overcome this problem. There is, for instance, the so-called thread pendulum which has not been found satisfactory because it does not contain a clockwork mechanism and thus does not provide audible signals which in many instances are desired, if they are not outright necessary. Other attempts have involved the com struction of metronomes of requisitely small size, using semiconductor circuits. This, however, has not been satisfactory because semi-conductor elements are highly susceptible to temperature fluctuations and because the number of such elements used in any particular unit must be held relatively small to avoid making the unit very expensive.

These above-mentioned approaches were used because there was general agreement that in the art that regular priorart metronomes could not be made small enough, that is that the pendulum could not be made small enough and still be able to set a tempo of between 40 and 208 impulses per minute because in small pendulums, wherein essentially the same frictional forces would have to be overcome as in large pendulums, no sufficiently free and therefore accurate swinging movement was capable of being achieved.

SUMMARY OF THE INVENTION It is, accordingly, an object of the present invention to provide an improved device of the type under discussion which is not possessed of the disadvantages of the prior art.

More particularly it is an object of the present invention to provide such a device which operates with great precision and uses a short-length pendulum, and wherein the short length of the pendulum does not disadvantageously afiect the precision of operation of the device.

Still another object of the invention is to provide such a device which has the advantages of the previously known large-size metronomes, including also the audibility of its acoustic signals, and which on the other hand is substantially smaller than the prior-art metronomes and fulfills the requirements according to the present invention.

In pursuance of the above objects, and others which will become apparent hereafter, one feature of the invention resides in a device for measuring repetitive identical time intervals, particularly for musical and medical use, comprising a housing and a shaft journalled in the housing for turning movement about an axis. The shaft has a first portion and a second portion with a pendulum being fast with the first portion and elongated radially of the axis for swinging movement about the same. A pair of anchor plates is mounted on the second portion in axially spaced parallel planes for movement therewith. These plates each have a first surface both of which face in one axial direction and a second surface which both also face in the opposite axial direction. Each of the first surfaces is inclined to an edge portion which extends at least substantially radially of the axis and which is convexly curved on a small radius in direction axially of the shaft towards the respectively associated second surface. A toothed wheel, that is a circumferentially toothed wheel, is mounted and biased for rotation in a plane which is at least substantially normal to the aforementioned parallel planes and which parallels the axis. Consecutive teeth of the wheel engage first one of the first surfaces so as to slide along the same to the edge portion thereof and to slide on the edge portion past the associated second surface while concomitantly imparting to the plates and thereby to the pendulum a turning impulse with successive audible abutment on the other of the first surfaces, and for thereupon sliding along the other of the first surfaces and the associated edge portion beyond the associated second surface while simultaneously a consecutive tooth abuts the first one of the first surfaces with an audible signal.

The pendulum of course receives a small turning impulse from each tooth of the toothed wheel, so that the loss of energy due to friction in the pendulum mount is compensated-for during each swinging movement of the pendulum so that the latter continues to swing with unchanged amplitude. Of course, in order to assure that the impulses imparted by the teeth of the toothed wheel do not influence the swinging amplitude of the pendulum, they must occur precisely at the moment in which the pendulum passes through its rest position. The teeth of the toothed wheel impart this impulse by contacting the so-called anchor plates which are mounted on the shaft on which the pendulum is also mounted. Heretofore the construction of such anchor plates received little attention because the time and the distribution of the impulses was of little consequence relatively speakingbecause the energy supplied to the pendulum during each such impulse was relatively small with respect to the energy of the swinging mass. However, when the mass of the swinging pendulum is smaller and the lever arms involved are shorter, as in the construction according to the present invention, the above features gain considerable importance. By constructing the anchor plates in the manner already briefly outlined above, I assure that the impulse is delivered precisely or almost precisely at the time the pendulum passes through its rest position and that each impulse acts upon the pendulum for only a very brief moment due to the selected inclination of the respective first surfaces and edge portionsand thereby assures that the frequency of free swinging movement of the pendulum is not disturbed.

in order to further reduce to a minimum the friction between the plates and the teeth of the toothed wheel at the moment at which the respective teeth slide over the curved edge portions from the respective first surface to the respective second surface, the edge portions are curved in the abovedescribed convex manner rather than terminating abuptly with a sharp edge as was customary heretofore. l have found it to be particularly advantageous if the curvature resembles the surface configuration of an axially halved circular cylinder whose diameter corresponds to the distance between the first surface and second surface of the respective anchor plate, that is to the thickness of the anchor plate.

I have also found it to be advantageous if the material of the anchor plates and of the toothed wheel, or at least of the teeth thereof, is so coordinated that the least possible friction will arise from contact between them. An advantageous combination of materials is for instance obtained if the toothed wheel, or at least the teeth thereof, is composed of a acetal resin and if the anchor plates are composed of steel. This also assures that the teeth of the toothed wheel, as long as they slide on the non-inclined portion of the respective first surface, exert only a very small braking action upon the pendulum so that the ideal circumstance of a freely swinging pendulum is further approximated.

A further advantageous embodiment provides also for at least one end portion of the shaft carrying the pendulum, to be adjustably joumalled. This makes it possible for adjusting the anchor plates exactly symmetrically with reference to the longitudinal axis of the pendulum, and also to obtain the proper distance to the center of the toothed wheel, circumstances which are of particular importance when the length of the pendulum is small. In this manner I achieve that the audible signals will take place at precisely equidistant time intervals if the pendulum is properly adjusted also.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a side view in a sectioned elevation and fragmentary illustration, of an embodiment of the invention with non-essential components having been omitted for clarify;

FIG. 2a is a top-plan view of a detail of FIG. 1;

FIG. 2b is an end view, as seen in the direction of the line 2b ofFlG. l, ofa detail of FIG. 1;

FIG. 2c is a fragmentary detail view on an enlarged scale, of the same detail shown in FIGS. 20 and 2b,-

FIG. 3 is a view somewhat similar to FIG. I but illustrating a detail of an embodiment for journalling the shaft;

FIG. 4 is a cross-section illustrating a journalling screw for the shaft;

FIG. 5 is a front view of an embodiment of the invention;

FIG. 6 is a top-plan view of an embodiment of the invention;

FIG. 7 is a bottom-plan view of an embodiment of the invention;

FIG. 8 is a vertical section, and side elevation, of an adjusting arrangement according to an embodiment of the invention;

FIG. 9 is a perspective view illustrating a preferred embodiment of the housing;

FIG. 10 is a fragmentary elevational view, on an enlarged scale, showing an embodiment of a pendulum;

FIG. 11 is a fragmentary sectioned detail view, on an enlarged scale, of a further embodiment;

FIG. 12 is a fragmentary elevational view illustrating another embodiment of the invention concerned with an arresting device for the pendulum;

FIG. 13 is a section taken on line 13-43 of FIG. 12; and

FIG. 14 is a top-plan view of FIG. 13.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing in detail it will be seen that in FIG. 1 I have illustrated an embodiment of the invention in which reference numeral I identifies a pendulum and reference numeral 2 a pendulum mounting arrangement which mounts the pendulum on the shaft or anchor shah 3. The pendulum shaft 3 also carries the so-called anchor 4 and is joumalled in bores of the support mount 3.

According to a preferred embodiment of the invention that portion of the anchor shah 3 which is remote from the pendulul I is mounted in a specially constructed journal which is to be described further detail with reference to FIGS. 3 and 4.

In a device such as is shown in its essential components in FIG. I, it is important that the pendulum in effect is capable of performing free swinging movements in order to obtain impulses at predetermined time intervals which should be as much equidistant as possible. The unavoidable losses due to friction, which serve to dampen the swinging movement of the pendulum and after a brief period of time would cause the pendulum to stop swinging, are compensated by regular impulses which are imparted to the anchor 4 by means of the toothed wheel 7 which is driven by a non illustrated conventional spring drive.

FIGS. Za-Zc illustrate details to show in which manner the drive impulses are transmitted to the anchor 4 by the toothed wheel 7. The anchor 4 is fast with the anchor shaft 3 and in FIGS. 20-20 it is shown in various enlarged views. As the Figures show, the anchor 4 comprises a first or front anchor plate 8 and a second or rear anchor plate 8a which are connected with one another and with the anchor shaft by connecting portion 9. The toothed wheel 7 is mounted for turning movement in a plane which is normal to the parallel planes of the

anchor plates

8 and 8a and which also encompasses the center axis of the anchor shaft 3.

For purposes of explanation it will be assumed that one tooth of the wheel 7 has just abutted against the first or front surface of the anchor plate and in so doing has produced an audible impulse or signal. This tooth now slides on the first surface of the anchor plate 8a in one direction until the pendulum reverses its swinging movement and thereupon the tooth slides on the same surface back in opposite direction until it comes to the inclined portion of the anchor plate 84.

According to the invention the inclined portion of the anchor plate 8 (and also of the anchor plate 8a) is of relatively short but steep configuration and constructed as a quaner circle 8d which is followed by an additional quarter circle 8b which leads to the rearwardly directed or second surface of the anchor plate 8. The juncture 8c of

quarter

8b and 8c is located on a tangent 8e to the plane of the wheel 7. In other words, the anchor plate may be considered as being composed of quadratic configuration with an axially halved portion of a cylinder secured to its narrow edge. So constructed, and assuming that the anchor plate is properly adjusted with reference to the wheel 7 on the shaft 3, the present invention assures that the anchor 4 receives a drive impulse exactly or almost exactly at the moment in which the pendulum passes through its rest or zero position. The drive impulse is brief but forceable and the tooth of the wheel 7 will then slide without being damaged or hindered by a sharp front edge of the anchor plate 8- passed the rear surface of the anchor plate 8 to abut against the front surface or first surface of the anchor plate 80 where it produces the next audible impulse or signal. This construction of the anchor plates as illustrated and described also assures that if the spring drive or the toothed wheel 7 should stop, the initially continuing movement of the pendulum does not permit the anchor plates to hit the teeth of the wheel because these teeth will under all circumstances slide past the curved or inclined surfaces of the anchor plates.

Having contacted the front surface of the anchor plate 80, the tooth described above now slides on this front surface in the manner described with respect to the anchor plate 8 until the pendulum reverses its direction, at which time the tooth again reverses its direction and exactly or almost exactly at the moment the pendulum passes through its zero position the tooth will slide off the curved edge of the anchor plate 80 beyond the rearward or second surface thereof, at the same time imparting again to the pendulum a drive impulse while simultaneously the next tooth of the wheel 7 abuts against the front face of the anchor plate 8 to provide the next audible signal.

In order to assure that the signals and impulses will actually take place at precisely spaced intervals, and that further the drive impulses will always take place precisely or at least substantially precisely at the moment at which the pendulum passes through its rest position or zero position, and further that the anchor plates will extend in a predetermined manner into the spaces between the teeth of the toothed wheel 7, it is necessary to very precisely adjust the anchor shaft 3. This is accomplished according to the present invention with the aid of the arrangements which are discussed hereafter with respect to FIGS. 3 and 4.

FIG. 3 shows that the anchor shaft 3 is journalled at its end remote from the pendulum I in a bore of a support or carrier 11 which is connected to a frame 36 by means of two mounting screws 10. Adjacent the bores for the mounting screws the carrier 11 is provided with further bores 12 which accommodate eccentric screws 13 which in turn are secured in a manner not separately illustrated to the frame 36. With the aid of the eccentric screw I3 it is possible to very precisely adjust the position of the journal of the carrier 11 with reference to the frame 36, and to thereby displace the carrier II with reference to the frame 36 laterally as well as upwardly and downwardly. As soon as the proper position for the carrier 11 has been adjusted, the mounting screws 10 which pass through bores of the carrier 11, and which bores must of course be greater than the thickness of the shafts of the screws, or tightened in order to fix the selected and adjusted position of the carrier 11 and therefore of the bore 14 for the anchor shaft 3.

According to FIG. 4 a further end portion of the anchor shaft 3 mounted carrier 11 is provided 14- with a bushing 15 having an eccentric bore. It is clear that with such a bushing 15 the height of the journalling for the anchoring shaft 3 cannot be adjusted completely independently of the lateral adjustment. However, it has been found that even the use of such a bushing 15 in actual practice has satisfactory results and that if the bushing is precisely adjusted by means of the adjusting slot illustrating in the drawing, satisfactory results can be obtained, especially if one keeps in mind the great simplicity of adjustment which is possible with this construction.

The bushing 15 shown in FIG. 4 serves for joumalling the front end of the anchoring shaft 3, as shown. However, it is quite clear that it can also be used for journalling and adjusting the rear end of the anchoring shaft 3 and that for instance the arrangements shown in FIGS. 3 and 4 can be combined with one another and that by means of the bushing 15 a precise adjustment can be carried out after the carrier 11 in such a combined construction has been set by means of the screws 10. If the setting slot of the bushing 15 need not be accessible from the exterior, then it is advantageous according to the present invention if the housing wall is provided with a steel plate which may also be made adjustable by means of a suitable screw arrangementas an abutment for that portion of the anchoring shaft 3 which passes through the sleeve 15, so that by properly constructing the end portion of the anchoring shaft 3 which bears upon the steel plate the friction can be further reduced.

It will be appreciated that in order to obtain the benefit of the construction according to the present invention, it is necessary that the pendulum itself be as long as possible and that its position with reference to the anchor shaft be capable of precise adjustment. Furthermore it is necessary to assure that the center of gravity of the pendulum body that is the actual lower weight on the pendulum shaftis located exactly on the pendulum axis. This is shown by way of example in FIG. 5 where an adjustment arrangement for the pendulum is illustrated.

FIG. 5 shows a device according to the present invention after it is mounted in the housing which has an open side that can be closed by means of a plate 33 after the device is mounted in the housing. In the illustrated embodiment that portion of the anchoring shaft 3 which carries the pendulum is provided with a pendulum holding arrangement 2 which is secured by a counter nut as shown in FIG. I. The pendulum has a pendulum shaft 19 which is wider in the region of the pendulum holding arrangement 2 and which in addition to its bore for the anchor shaft 3 is formed with slots 20 located on a circle concentric with this bore. In these slots there extend the shafts of two screws which can be threaded into the pendulum holding device 2 and which permit positioning of the pendulum shaft in its proper location with reference to the pendulum holding device once the proper orientation has been obtained.

possibility for adjusting one is obtained if the stationarily in place of a simple bore The pendulum shaft 19 carries at its upper region an adjustable pendulum weight 17, and at its lower end portion a lower pendulum weight or pendulum body 18. The body 18 is mounted on the pendulum shaft 19 by means of a connecting element 22 which in the illustrated embodiment is configurated as a screw but which can also have the form of a bolt or analogous means. The element 22 can be displaced along a transverse slot 23 provided in the body 18 and, in order for the pendulum shaft 19 to follow the displacements of the element 22 the interior of the body 18 is provided with a recess 2| which is shown in broken lines in FIG. 5 and whose dimensions are in excess of those of the lower portion of the pendulum shaft 19 which is to be accommodated in the pendulum body 18. It would of course also be possible to make the lower end portion of the pendulum shaft 19 correspondingly wider and to provide it with a slot corresponding to the slot 23 for making the connecting element displaceable for adjusting purposes; in this case the connecting element would have to be fast with the body 18 or, if the body 18 were to be composed of several parts, it would have to be fast with these parts. If the pendulum shaft is configurated as illustrated then it is particularly advantageous to construct the pendulum body 18 of one piece and to secure it on the reverse side of the pendulum shaft, that is between the pendulum shaft and the plate 33 of the housing 25, because in this manner the center of gravity of the device is advantageously displaced closer towards the center of the bottom wall of the housing 25 whereby the stability of the device is enhanced.

By utilizing the construction shown in FIG. 5 it is possible to adjust the center of gravity of the pendulum body 18 precisely with reference to the center axis of the pendulum shaft 19. This, as well as the adjustment of the pendulum rod 19 with reference to the anchor shaft 3 is necessary to assure that the periodicity of the pendulum swings is maintained exactly constant, and also to further assure that a known-symmetrical arrangement of the pendulum -which would not necessarily disadvantageously affect the periodicity of the pendulum swinging movementsdoes not disadvantageously affect the regularity of the audible signals. The signals are to be entirely regular in their succession, that is the displacement of the pendulum must be as symmetrical with reference to the rest position as possible.

It will be appreciated that adjustments as outlined above are made when the device according to the present invention is in a precisely vertical position. Evidently, therefore, it is desirable that during use the device be similarly precisely vertical in order to obtain maximum benefit from the accuracy of the previous made adjustment. This, of course, requires that the user is able at all times to readily ascertain that the device is properly vertically oriented, and is able to take the necessary measures should this not be the case. FIGS. 6 and 7 show embodiments of the invention which make this possible.

In the embodiment of FIG. 6 the upper side of the housing 25 is provided with a tube-type spirit level 24 which permits a rapid checking whether at least the side edges of the housing are oriented vertically. This is particularly important because if the housing is not precisely vertically oriented, the device will produce audible signals irregularly. An inclined position will reference to the front and rear edges of the housing as opposed to an inclined position with respect to the side edges thereofcauses the number of impulses given on the scale not to be precisely maintained because the inclination of the housing in effect acts as would a change in the gravity acting on the pendulum.

FIG. 1 shows the bottom of a housing of a device according to the present invention, and indicates that the bottom is provided with adjusting screws 26 of which at least one should be providedwhich may if desired be provided on the flange projecting beyond the bottom of the housing. The adjusting screws 26 make it possible to compensate for displacements of the housing from the vertical. At the edges opposite the adjusting screws the housing rests on a projection 35 which preferably is connected of one piece with the housing 25 by a molding or pressing operation.

FIG. 8 shows a further arrangement for adjusting the device according to the present invention. In this embodiment the arrangement for adjusting is effected not as in the FIG. 7, but via a lateral setting screw 32 by means of which the entire internal components can be displaced within the housing. For this purpose they are mounted turnably on a tilting axis 30 by means of two brackets 31, with the tilting axis 30 extending in the upper part of the housing in parallelism with the anchor shaft 3. The setting screw in the embodiment of FIG. 8 is so constructed that a pin which is journalled in the support against turning movement is provided at its front end with a thread and has a certain amount of play, and cooperates with the internal thread provided in a setting screw 32 which is configurated as a take-along, with the screw 32 also having an external thread which is in mesh with threads provided in the housing wall.

FIG. 9 shows a complete device according to the present invention in perspective illustration. It will be seen that for such times when the pendulum is not in use it can be covered by means of a cap 28. In this embodiment the tube-type spirit level is replaced with a box level 27 at the underside of the housing. FIG. 9 also shows that the housing wall is provided with openings 29 for sound emission which facilitate audibility of the audible signals and which may be provided at any desired point of the housing. In order to provide for a good connection of the cap 28 with the remainder of the housing 25, the housing is provided with folds I6 extending circumferentially, and the cap 28 is similarly provided with folds l6 interengageable with those of the housing, as shown for instance in FIG. 5. Snap-action elements may additionally be provided on the housing and the cap 28 for releasable interengagement.

According to another embodiment of the invention the pendulum shaft 19 may be so configurated that its length is greater than the maximum dimension of the housing 25. As shown in FIG. 10 this can be accomplished in that the pendulum shaft I9 is composed of an upper portion 19a and a lower portion 1% which can be connected by means of a connecting arrangement 19c which can also be a part of the upper portion 190. It is also possible to make the pendulum shaft l9 telescopable in known manner, or to connect the sections thereof hingedly so that they can be collapsed when not in use, or to make the pendulum shaft of flexible material so that it can be flexed and accommodated in flexed condition in the interior of the housing when not in use. Any one of these possibilities assures that the housing which in any case will have a height of less than 150 mm can be made still smaller, or that the effective length of the pendulum during the operation of the device can be increased, without having to increase the dimensions of the housing. The construction of the pendulum or the pendulum shaft according to the present invention thus can be made use of not only with devices which utilize the particularly configurated anchoring plates according to the present invention, but any devices of the type under discussion. However, the inventive construction of the pendulum shaft is particularly advantageous in conjunction with the other features of the invention.

FIG. I also shows a particularly advantageous construction for the upper adjustable pendulum weight 17. It is already known that these weights conventionally use a spring which on the one hand serves to maintain the pendulum weight 17 at a preselected position longitudinally of the pendulum rod 19, and which on the other hand snaps into transverse grooves provided in the pendulum shaft I9, with the grooves being located in accordance with the selected number of swing intervals. Heretofore it was customary to construct this spring as a separate component which was connected with the pendulum weight 17 itself, with the latter preferably consisting of lead or the like and being composed of a front plate, the actual weight secured to the front plate, and the spring. The front plate essentially had no other purpose than to improve the aesthetic appearance because they almost exclusively used lead weights and tend to appear rather unattractive due to oxidation over a period of time. The present invention in the embodiment illustrated in FIG. 10 proposes to simplify the construction of the adjustable weight 17 by constituting the spring as a portion of the front plate itself. Thus, the front plate is constructed of a springy material, for instance spring steel, and in the region of the pendulum shaft 19 it is provided with two slots which extend essentially in parallelism with the longitudinal axis of the pendulum shaft 19 so that a springy tongue exists which is connected at its opposite ends with the remainder of the front plate. By lightly displacing this tongue inwardly there is then obtained the spring 39 which engages the pendulum shaft 19. Such a construction makes the production of the upper adjustable pendulum weight I7 less expensive than heretofore, a consideration which is particularly advantageous and important in a small-dimensioned metronome according to the present invention because the price in such small devices is of course of particular importance. Of course, it will be appreciated that this aspect of the invention can also be used to advantage with conventional larger metronomes.

Finally, FIGS. I 1-14 illustrate still a further embodiment of the invention in which means are provided for increasing the audibility of the signals produced by the device. For this purpose the housing 25 is provided in one of its walls with a vibratory membrane 27 which is advantageously but not excusivelyof heat steel. The rear end portion of the anchor shaft 3 abuts against this membrane or diagraphram 37 whereby the individual audible signals are reliably and advantageously transmitted to the diaphragm with the accoustical signal being emitted through an opening 38 which is located behind or exteriorly of the diaphragm 37 and which preferably conically diverges in outward direction. In this construction the diaphragm 37 can of course also serve as an abutment for the anchor shaft 3.

Again it will be appreciated that the embodiment in FIGS. 11-14 can be used not only in conjunction with the other features according to the present invention, but can also be used in conventional metronomes of all types. However, it is especially advantageous in conjunction with the device according to the present invention because it assures proper audibility of the signals even if the force with which the teeth of the wheel 7 abut against the

plates

8 and 8a is reduced, which in turn makes it possible to use a spring drive of less power and therefore a spring drive which is less expensive.

In all embodiments of the invention it is advantageous, particularly because the device is to be readily transportable, to provide the front side of the housing or the front plate thereof with an arresting means for preventing the pendulum from swinging when this is not desired. As FIG. 6 shows such an arresting device can be configurated as an arresting bracket 34. However, as shown in FIGS. 12-14 a preferred embodiment of such a device is in form of a projection 40 provided at the center of the front edge at the upper side of the housing 25, which in turn is provided with a recess the width of which is approximately as great as the width of the pendulum shaft 19. The depth of the recess also corresponds approximately to the depth of the shaft 19. To assure a proper arresting of the tip of the shaft I9 in the recess the open front side of the recess at the right and the left may be provided with a small bead or the like so that the free opening is somewhat smaller than the width of the shaft 19 which is then pressed with light pressure into the recess until it slides past the beads and abuts against the rear wall of the recess.

The upper side of the projection preferably is not flush with the upper side of the housing, but slightly downwardly displaced with reference thereto. This makes it possible to pro vide the cap 28 with a corresponding recess 41 which then overlies the projection so that the latter is no longer visible when the housing is closed by the cap 28.

This latter possibility is partially shown in FIGS. "PM, so that a portion of the upper side of the projection is visible when the housing is closed whereas another portion is covered by the cap 28. This embodiment has the advantage that the strength of the arresting element, which is generally limited by the wall thickness of the housing 25, is increased which is evidently desirable.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a device for measuring repetitive identical time intervals, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended l. A device for measuring repetitive identical time intervals, particularly for musical and medical use, comprising a housing; a shaft journalled in said housing for turning movement about an axis and having a first portion and a second portion; a pendulum fast with said first portion and elongated radially of said axis for swinging movement about the same; a pair of anchor plates mounted on said second portion in axially spaced parallel planes for movement therewith, said plates each having a first surface both facing in one axial direction and a second surface both facing in the opposite axial direction, and each of said first surfaces being inclined to an edge portion extending at least substantially radially of said axis and convexly curved on a small radius in direction axially of said shaft towards the respectively associated second surface; and a circumferentially toothed wheel mounted and biased for rotation in a plane at least substantially normal to said parallel planes and paralleling said axis, consecutive teeth of said wheel engaging first one of said first surfaces so as to slide along the same to said edge portion and to slide on said edge portions past the associated second surface while concomitantly imparting to said plates and thereby said pendulum a turning impulse with successive audible abutment on the other of said first surfaces, and for sliding along the other of said first surfaces and associated edge portions beyond the associated second surface while simultaneously a consecutive tooth abuts the first one of said surfaces.

2. A device as defined in claim 1', and further comprising weight means mounted on said pendulum displaceable longitudinally of the same towards and away from said axis for concomitantly varying the period of swing of said pendulum.

3. A device as defined in claim 1, wherein the convex curva ture of the respective edge portions resembles the outline of an axially bisected circular cylinder whose diameter corresponds to the distance between the first and second surface of the respective anchor plate.

4. A device as defined in claim 1, said anchor plates and toothed wheel being composed of material so selected as to have minimum friction during relative contact between said toothed wheel and the respective anchor plates.

5. A device as defined in claim 4, wherein said toothed wheel is made from acetal resin and said anchor plates from steel.

6. A device as defined in claim 1, said shaft having opposite end portions; and further comprising journal means journalling said opposite end portions and wherein at least one of said journal means journals the associated end portion adjustably.

7. A device as defined in claim 6, said one journal means comprising a journal support and a bushing turnably mounted in said journal support and having an axially extending eccentric journal bore in which said associated end portion is accommodated.

8. A device as defined in claim 6, said one journal means comprising a support, a journal for said associated end portion, and a pair of excenter screws on opposite sides of said journal and acting upon said support in a sense displacing the same with reference to the other journal means.

9. A device as defined in claim 1; and mounting means mounting said pendulum on said shaft adjustably displaceable with reference to the same.

10. A device as defined in claim 9, said mounting means comprising a pendulum-holding element secured to said shaft and having a passage for receiving a portion of the pendulum shaft, and at least one set screw threaded into said element so as to project into said passage and having a screw portion extending into a slot provided in said pendulum shaft.

11. A device as defined in claim 1, said pendulum having a pendulum shah and a pendulum body; and wherein said pendulum body is so configurated as to afford a lowest possible center of gravity for said pendulum consonant with a maximum permissible length of said pendulum in direction normal to said shaft.

12. A device as defined in claim 11, said pendulum body having the shape of a sector of a circular disk having a blunt tip provided with an edge face which extends normal to a radial center line of said sector.

13. A device as defined in claim 1, said pendulum having a pendulum shaft and a pendulum body mounted on said pendulum shaft displaceable longitudinally of the same.

14. A device as defined in claim 13, said pendulum body having a recess and a transverse slot, said recess being larger than the outline of that portion of said pendulum shaft which is received therein; and further comprising a connecting element connecting said pendulum body with said pendulum shaft and being slidable in said transverse slot.

15. A device as defined in claim 14, said transverse slot having the shape ofa portion of are centered on the center axis of said pendulum body.

16. A device as defined in claim 1, said housing having a bottom wall; and further comprising at least one adjusting screw on said bottom wall exteriorly of said housing for enabling adjusting of the orientation of the latter with reference to a surface on which said bottom wall is supported.

17. A device as defined in claim 1, said housing having an upper portion and a lower portion; and further comprising a pair of mounting members mounting said pendulum, anchor plates and wheel turnable about a turning axis in said upper portions and paralleling said shaft.

18. A device as defined in claim 17, said wheel comprising a spring drive; and further comprising a set screw for arresting said spring drive in a desired angular position upon turning about said turning axis.

19. A device as defined in claim 1; and further comprising sound apertures in said housing for facilitating emission of sound therefrom.

20. A device as defined in claim 1, wherein said housing is substantially cubical and has an open side for insertion and removal of the components accommodated in said housing.

21. A device as defined in claim 20, said housing having a plurality of peripheral walls bounding said open side and provided with a fold; and further comprising a correspondingly folded cap member engageable with said folds of said peripheral walls for removably covering said open side.

22. A device as defined in claim 1, said housing having a front wall provided with a projection having a recess; and wherein said pendulum is located outwardly adjacent said front wall and comprises a pendulum shaft partially receivable in said recess for arresting said pendulum against undesired swinging motion.

23. A device as defined in claim 1, said housing having a minimum dimension and a maximum dimension; and wherein said pendulum comprises a pendulum body and a pendulum shaft which connects said pendulum body with said shaft, said pendulum shaft having a longitudinal dimension greater than said maximum dimensions of said housing.

24. A device as defined in claim 23, wherein said pendulum shaft is composed of a plurality of telescopable sections.

25. A device as defined in claim 23, wherein said pendulum shaft is composed of a plurality of hinged collapsible sections.

26. A device as defined in claim 23, wherein said pendulum shaft is composed of a plurality of connectable sections.

27. A device as defined in claim 23, wherein said pendulum shaft is composed of flexible material and is accommodatable in flexed condition in the interior of said housing.

28. A device as defined in claim 1, said housing having a peripheral wall provided with an oscillatable diaphragm.

29. A device as defined in claim 28, wherein said diaphragm is a steel disk and constructed as an abutment for an end portion of said shaft which is remote from said pendulum.

30. A device as defined in claim 29, said diaphragm being located on an inwardly facing side of said wall; and wherein said wall is provided at the outwardly facing side thereof with an opening which registers with said diaphragm and diverges inwardly in direction towards the same.

31. A device as defined in claim 30, wherein said opening diverges conically.

32. A device as defined in claim I, said pendulum comprising a pendulum shaft carried by said shaft, a pendulum body on said pendulum shaft, and a pendulum weight also on said pendulum shaft and wherein said weight is provided with a passage through which said pendulum shaft extends and a springy portion of said weight is deflected into said passage and into frictional engagement with said pendulum shaft.

33. A device as defined in claim I, said housing having an upper wall provided with a box level.

34. A device as defined in claim 1, said housing having an upper wall provided with a tubular level.

35. A device as defined in claim 34, said tubular level com prising a liquid-containing tube having a longitudinal axis which extends in parallelism with the plane of swinging movement of said pendulum.

I B t i i

Claims

1. A device for measuring repetitive identical time intervals, particularly for musical and medical use, comprising a housing; a shaft journalled in said housing for turning movement about an axis and having a first portion and a second portion; a pendulum fast with said first portion and elongated radially of said axis for swinging movement about the same; a pair of anchor plates mounted on said second portion in axially spaced parallel planes for movement therewith, said plates each having a first surface both facing in one axial direction and a second surface both facing in the opposite axial direction, and each of said first surfaces being inclined to an edge portion extending at least substantially radially of said axis and convexly curved on a small radius in direction axially of said shaft towards the respectively associated second surface; and a circumferentially toothed wheel mounted and biased for rotation in a plane at least substantially normal to said parallel planes and paralleling said axis, consecutive teeth of said wheel engaging first one of said first surfaces so as to slide along the same to said edge portion and to slide on said edge portions past the associated second surface while concomitantly imparting to said plates and thereby said pendulum a turning impulse with successive audible abutment on the other of said first surfaces, and for sliding along the other of said first surfaces and associated edge portions beyond the associated second surface while simultaneously a consecutive tooth abuts the first one of said surfaces.

2. A device as defined in claim 1; and further comprising weight means mounted on said pendulum displaceable longitudinally of the same towards and away from said axis for concomitantly varying the period of swing of said pendulum.

3. A device as defined in claim 1, wherein the convex curvature of the respective edge portions resembles the outline of an axially bisected circular cylinder whose diameter corresponds to the distance between the first and second surface of the respective anchor plate.

11. A device as defined in claim 1, said pendulum having a pendulum shaft and a pendulum body; and wherein said pendulum body is so configurated as to afford a lowest possible center of gravity for said pendulum consonant with a maximum permissible length of said pendulum in direction normal to said shaft.

15. A device as defined in claim 14, said transverse slot having the shape of a portion of arc centered on the center axis of said pendulum body.

31. A device as defined in claim 30, wherein said opening diverges conically.

32. A device as defined in claim 1, said pendulum comprising a pendulum shaft carried by said shaft, a pendulum body on said pendulum shaft, and a pendulum weight also on said pendulum shaft and wherein said weight is provided with a passage through which said pendulum shaft extends and a springy portion of said weight is deflected into said passage and into frictional engagement with said pendulum shaft.

33. A device as defined in claim 1, said housing having an upper wall provided with a box level.

35. A device as defined in claim 34, said tubular level comprising a liquid-containing tube having a longitudinal axis which extends in parallelism with the plane of swinging movement of said pendulum.