Pyramidal Metronome

Abstract

A generally pyramidal cabinet for a metronome is formed by a molded truncated pyramidal body portion having appropriately arrange d integrally formed elements coacting with a cap portion, a base portion and a cover portion to hold the cabinet together without the use of additional fasteners.

Description

The present invention relates to a pyramidal cabinet for a metronome, having a body portion shaped in a truncated pyramidal form, a cap portion, and a base portion, and an opening located in one of the surfaces of the body portion and susceptible of being closed by a cover portion.

It is known that metronome cabinets of the above described type, which were originated by Maelzel more than 150 years ago are still in very widespread use. On the other hand due to the high cost of manufacturing, it is no longer economically possible to manufacture such cabinets of wood, as was done heretofore. Therefore, experiments have been made in manufacturing these cabinets of plastic material. It was discovered, however, that thin-walled plastic cabinets, which would be easy and cheap to manufacture and which should also be preferable for reasons of good resonance and strength, have the tendency to warp at high temperatures so that in the tropics they cannot be used.

Thus, one object of the invention is to provide a metronome cabinet having the classical pyramidal form, which can be manufactured in the form of a thin-walled body and which, however, retains its shape even at abnormally high temperatures, and which is simple and cheap to manufacture.

This object can be accomplished, according to the invention, by forming the truncated pyramidal body portion in the shape of a unitary plastic portion with its walls diverging toward a base portion and which is locked, preferably by cooperating elements with said base portion and the cap portion, the cover portion being releasably secured to the body and cap portions.

With a metronome cabinet of this type it is possible to reinforce the relatively thin-walled body portion, by means of the base portion, to such an extent that no perceptible deformation due to excessive heat can occur.

This aim may particularly be accomplished in a technically and economically advantageous manner if, according to a preferred embodiment of the invention, the base portion of the cabinet is provided with protrusions along its margin, which engage with corresponding notches located on the inner wall of the body portion. Further, the separate manufacture of the cap portion has the advantage that if irregularities exist in the upper part of the body portion, caused by the injecting machine for the plastic material, they are covered by the cap portion, and that the need for trimming the upper edge of the body portion can be avoided. According to a preferred embodiment of the invention, both the locking device for the pendulum of the clockwork which is to be inserted into the cabinet of the metronome, and a protrusion to secure the cover portion of the opening provided in one of the surfaces of the body portion, are part of the cap portion which can also be manufactured as a simple plastic molding. Further, the separate manufacture of the cap portion has also proved to be convenient due to the fact that, if the body portion is coated, for example with plastic sheets, it is not necessary to carry out the coating operation at the upper end of the body portion in a particularly careful manner, since it is also covered by the cap portion. The circumstances are analogous at the lower edge of the body portion, where the coating can, if necessary, be folded towards the inside to be held by the base since the base portion is separately inserted.

Further advantages and features of the invention will appear in more detail from the following description of a preferred embodiment, made in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of a pyramidal metronome cabinet, according to the invention;

FIG. 2 is a sectional fragmentary view along line 2--2 of the cabinet shown in FIG. 1;

FIG. 3 is a fragmentary sectional view along line 3--3 of the cabinet shown in FIG. 1;

FIG. 4 is a sectional view along line 4--4 in FIG. 3;

FIG. 5. is a fragmentary section view along line 5--5 of the metronome cabinet shown in FIG. 1;

FIGS. 6 and 7 are views from the bottom of the open body portion of a metronome cabinet of the invention respectively before, and after, the clockwork has been inserted therein.

FIG. 8 is a view of the under side of the base portion.

More particularly, FIG. 1 shows that the pyramidal cabinet for a metronome, according to the invention, comprises a body portion 1, a cap portion 2 and a cover portion 3, while the bottom portion of the cabinet cannot be seen since it is located inside the body portion. It can be appreciated that underneath the cover portion 3, which consists of transparent material, a graduated scale 4 is arranged whose indicia correspond to the stroke numbers which are obtained by moving the weight 5 along the pendulum bar 6 of the clockwork arranged inside the cabinet to the height of each respective indicia. A key 7 is also provided for winding the spring of the clockwork.

According to the invention, the body portion of the cabinet shown in FIG. 1 is formed as a unitary plastic molding. Since the base portion located inside the cabinet and near the lower end thereof provide a stiffening effect for the body portion, the wall thickness of this body portion can be relatively thin, without any risk that the cabinet will warp under the effect of excessive heat.

As can be best appreciated in FIGS. 2 and 5 to 8, the base portion 8, which is provided with three legs 9 located on its under surface, is inserted at the inside of case portion 1 and abuts a shoulder 10, while protrusions 11 provided along the periphery of the base portion 8 engage with corresponding notches 12 provided on the inner surface of case portion 1.

To permit removal of the inserted base portion 8 from the body portion 1, the base portion 8 is further provided with an opening 13 into which a tool, for example a screw driver, can be inserted to press the bottom portion out of its engagement. By appropriately selecting the materials of body portion 1 and base portion 8, as well as properly dimensioning the notches 12 and the protrusions 11, it is possible to repeatedly remove the base portion from the cabinet, for servicing the clockwork, and to reinsert it therein, without damaging the affected parts.

FIG. 8 further shows that the bottom portion is provided with acoustic slots 14 which permit the unimpeded passage of sounds produced inside the cabinet. Further, an opening 15 is provided in the middle of the bottom portion shown in FIG. 8, into which the shaft of key 7 can be inserted to be held therein, for carrying purposes, once it has been unscrewed from the drive shaft of the clockwork.

As shown in FIG. 2, a divider panel 16 is provided on the inside of base portion 8 in order to prevent the lower weight 17 of the pendulum from striking against the wheel (not shown) of the clockwork, in case of any excessive shock to the metronome.

In FIGS. 6 and 7, particularly, but also in FIGS. 2 and 5, it is shown how the clockwork of the metronome is secured to the metronome cabinet of the invention. As shown in FIG. 6, the inner surface of the body portion 1 is provided with vertical projections 18 which serve to mount the clockwork when it is placed inside the cabinet. These projections are reinforced along their lengths by means of reinforcing ribs 19.

The clockwork, generally indicated by numeral 21, is secured by means of threaded bolts 20, which are screwed into suitably threaded bores within the projections 18. FIG. 5 shows a cross-sectional view of one of the projections 18. It is apparent that the mounting of the clockwork in the cabinet can be carried out, in a particularly simple manner, by inserting it from the bottom, since only the four bolts need to be screwed into the projections. It should also be noted that there is no connection between the pendulum shaft 22 of the clockwork and the cabinet as is usual in some known metronomes. In case of repair, in these known metronomes, the bearing for the front end of the pendulum shaft and the pendulum bar 6 supporting the two weights have to be separated from the shaft itself before the clockwork can be removed.

As shown in FIG. 1, in connection with FIGS. 3 to 5, the attachment of the cover portion 3 is achieved, in a preferred embodiment of the invention, by means of a slotted projecting nose 23. This nose 23 is received within a recess 24 provided at the top of the cover portion 3 which also has offset flanges 25 along the lower margin. These flanges abut the inner side of the body portion at the lower margin of the opening provided at the front side thereof. It has proven to be particularly convenient if the recess 24 located in the cover portion 3 comprises two concentric bores of different diameters, whereby the smaller bore is located nearer the inner surface of the cover portion and has a diameter slightly smaller than the diameter of a bead which is formed at the free end of the projecting nose 23. With this configuration the slot 26 in the projecting nose is first compressed when the cover portion 3 is applied, so that the bead of the projecting nose 23 can pass through the smaller bore. As soon as the bead has passed through the smaller bore the slot 26 opens and the bead of the projecting nose 23 engages with the shoulder of the recess 24, so that the cover portion 3 is secured.

In addition to the projecting nose, the cap portion 2 is provided with a downwardly projecting wall 27, as shown in FIGS. 3 and 4, which defines a groove 28 for holding the upper end of the pendulum bar 6 when stopped. It is apparent that the configuration of the cap portion results in a very simple cabinet which has the advantage, in addition to the above mentioned ones, that relatively simple tools can be used to manufacture the injection molds for the body portion of the cabinet.

According to a further feature of the invention, a separating wall 29 carrying a scale is located inside the body portion 1, lying in a plane parallel to the front surface of the body portion and connected to the opposite sides of the body portion. This separating wall 29 extends further downwards than the lower edge of the opening in the front surface of the cabinet, and is provided with recesses in its lower end to permit the passage of the front support 31 for the shaft 22. A bearing 32 for the shaft is mounted on the front of support 31 and rests on an abutment 33 provided on the inner surface of the body portion 1 (see FIGS. 2, 6 and 7). This abutment 33 permits a quick and accurate centering of the clockwork during the installation thereof. In addition, the front pendulum shaft bearing 32 is provided with a concave hardened positioning disk which pushes against the abutment, when the clockwork is installed, thus insuring that the strokes of the metronome are directly transmitted from the shaft to the cabinet and, consequently, produces a loud striking of the instrument.

Finally, it will be apparent that the embodiment of the pyramidal metronome cabinet of the invention has particular advantages if the body portion of the cabinet is to be covered with a coating, for example, a decorated plastic coating. As it has already been mentioned above, no particular attention has to be given to the appearance of the upper margin of the body portion, since the upper edges are covered by the cap portion 2. The conditions are the same at the lower end of the body portion, where a coating can simply be folded towards the inside and be clamped by the bottom portion 8 when it is inserted. If body portion 1 is to be provided with a coating it has proved to be particularly convenient to use plastic coatings having the appearance of grained wood which gives the impression that the cabinet is made of solid wood as was the custom in the past.

Claims

I claim:

1. A pyramidal cabinet for a metronome comprising an enclosure of plastic material including a unitary truncated pyramidal hollow body portion the side walls thereof terminating at their upper and lower margins in respective common horizontal planes defining top and bottom openings, a removable cap portion received in said top opening to overlie said upper margins, a removable base portion receivable in said bottom opening in engagement with the side walls adjacent their lower margins, a removable cover portion, one of said side walls being provided with an opening to receive and removably retain the lower end of said cover, said cover portion being additionally removably secured to the cap portion, at least two of the side walls of said body portion also including an element integrally formed in a medial portion thereof for attachment to a clockwork means, whereby the cap and base portions and said clockwork means cooperate with the side walls of the body portion to increase the rigidity of the cabinet.

2. A cabinet as defined in claim 1, wherein said body portion is provided at the inside with recesses to receive respective protrusions provided along the margins of the cap and base portions, and is also provided with shoulder means to abut the cap and base portions in their assembled positions.

3. A cabinet as defined in claim 2, wherein said body portion is provided at the inside with a separating wall parallel to the plane of said opening for the cover, said wall carrying a scale.

4. A cabinet as defined in claim 3, wherein said cap portion is provided with compressible projecting means to be received in a recess provided in said cover portion, and with a protrusion defining a groove.

5. A cabinet as defined in claim 4, wherein said base portion is substantially flat and is provided with acoustic slots, including a first opening to insert a tool, a second opening to insert a winding key, a vertical separating wall on its inner surface, and with a plurality of legs on its outer surface.

6. A cabinet as defined in claim 5, wherein said cover portion is provided at its lower end with protrusions engaging with the inner surface of the body portion near the lower edge of said opening in the body portion.

7. A cabinet as defined in claim 6, said clockwork means being of the type including a pendulum bar, a lever shaft and lever shaft bearings, said groove provided in the cap portion receiving the upper end of the pendulum bar in the inoperative position of the metronome, and an abutment provided at the inside of the body portion cooperating with one of said lever shaft bearings.

8. A cabinet as defined in claim 6, wherein said body portion is provided with a coating.

9. A cabinet as defined in claim 8, wherein said coating comprises a figured plastic sheet.

10. A cabinet as defined in claim 9, wherein said plastic sheet has a wood grain appearance.

11. A cabinet as defined in claim 8, wherein said coating comprises a varnish.

12. A cabinet as defined in claim 11, wherein said varnished coating includes a pattern having a wood grain appearance.

13. A cabinet as defined in claim 8, wherein said coating is printed on the body portion.