SIMPLIFIED MECHANICAL FOR ACCORDION BASS KEYBOARD

DESCRIPTION

The object of the present patent application for industrial invention is a simplified mechanical for accordion bass keyboard.

As known, accordion mechanicals are quite complex and sophisticated as they are comprised of a large number of levers, rods and transmissions able of ensuring that the pressure exerted by the performer on each key returns the raising of one or more of the valves cooperating with the holes of the inner reeds.

The specific object of the present invention is just that of reducing the number of mechanical components that carry out the interaction between each key of the bass keyboard and the corresponding valves cooperating with the respective reed. To this end it should first be noted that the bass keyboard of any accordion is developed longitudinally on the front of a carrying casing also adapted for supporting and containing the respective reed, arranged in longitudinal direction as well. It should also be noted that the operation of any bass keyboard envisages that the pressure of a single key returns the concurrent raising of a plurality of inner valves. Within the scope of such a traditional structure, it is envisaged that each key of the aforesaid keyboard must be able of carrying out alternate strokes (alternately due to the user's pressure and to the suitable elastic return means) in a plane that is orthogonal to the axis of the carrying casing. Similarly, it is envisaged that each of the valves controlled by the various buttons must be able of carrying out alternate oscillations (approaching and away from the respective

CONFIRMATION COPY

hole of the reed) in a plane that is also orthogonal to the axis of the same carrying casing.

In short, this means that the planes within which the various keys and the corresponding valves carry out alternate strokes are parallel to each other. Such condition sets the need of adopting a series of mechanical components such as to ensure that each key and the corresponding valves may move integrally and concurrently within the aforesaid respective parallel planes.

To better understand the real essence and the actual advantages of the subject finding it is appropriate to describe, even though in brief, the most common technology adopted so far for the operation of accordion bass keyboards; to this end, it is appropriate to refer to the relevant figure 1 annexed to the present description.

In the presence of the traditional technology it is envisaged that each key of the bass keyboard actuates a sliding stem (neither shown in the above figure 1) adapted for actuating a pivoting lever (100) hinged at the base, along with all the further similar levers, at a shaft (110) arranged parallel to the longitudinal axis (X-X) of the casing supporting the entire bass keyboard.

This means that said lever (100) is in the condition of carrying out alternate oscillations within a vertical plane that is orthogonal to the above axis (X-X) of the casing itself, the same that also contains the relevant actuating button. At about half height of this lever (100) there is keyed a particular arm articulated as an upturned "L" (120), whose bottom end is welded on top of a turning rod (130), belonging to a compact "pack" of many similar rods keyed into a respective support frame (130a), also arranged longitudinally relative to the bass keyboard casing.

When the performed presses one of the keys on the bass keyboard, a backward oscillation of the respective lever (100) is produced which is punctually transmitted, thanks to the return action ensured by the above articulated arm (120), to the respective turning rod (130).

Moreover, on top of each of said turning rods (130) there are fixed one or more shaped arms (140) that take on a setup orthogonal to the respective rods (130) and that are oriented in a direction opposite to that occupied by the above lever (100).

Each of such shaped arms (140) is hooked to the lever (150a) of one of the valves (150) really intended for interacting with the holes of the bass reed (not shown in the above figure).

In particular these valves (150) occupy a position below the aforesaid pack of turning rods (130) and are keyed, perpendicular to the latter, at a special frame (160) arranged in parallel position and right opposite the above shaft (110) integral with the above lever

(100).

This implies that the above backward rotation of each rod (130) also causes - opposite the relevant support frame (130a) - the raising of the respective shaped arms (140) integral thereto and, as a consequence, the raising of the corresponding valves (150) relative to the reed holes.

In this way it is understood how the return action ensured by the above turning rods

(130) in longitudinal position makes the backward stroke of the lever (100) and the raising of each valve (150) corresponding thereto, integral and concurrent. It can be said that the same return action exerted by each rod (130) puts into effect the desired matching between the oscillations that the above lever (100) carries out in a vertical plane, orthogonal to the respective longitudinal rod (130), and the oscillations that the corresponding valve (150) carries out in a respective vertical plane, also orthogonal to the same rod (130). It is just the case to say that as soon as the user's pressure on the bass keyboard key stops, all the above mechanical components, integral to one another, are returned to the starting position by suitable elastic return elements. hi particular, reference is made to the spring (170) cooperating with the lever (150a) of each valve (150). At the end of this brief description of the prior art it is easier to understand the specific purposes of the present invention that, in particular, lie in the will of eliminating some of the aforesaid traditional mechanical components. hi particular, reference is made to the above articulated arm (120) that puts into effect the connection between the lever (100) and the respective turning rod (130), to the shaped arm (140) that puts into effect the connection between the same turning rod

(130) and the lever (150a) of the respective valve (150), as well as the frame (160) on which the levers of all valves are keyed.

Such simplification was made possible thanks to an innovative and original solution idea, by which it has been envisaged to change the setup of those turning rods that must in any case put into effect the return action between the lever directly stressed by a key of the keyboard and the respective valve cooperating with one of the reed holes. In the new subject mechanical, in fact, the above turning rods do not adopt a setup exactly parallel to the longitudinal axis of the casing relating to the bass keyboard, but rather a setup considerably inclined relative to the same longitudinal axis. For higher clarity of description, the disclosure of the finding continues with reference to the annexed drawing tables, having an illustration non-limiting value, wherein:

- figure 2 shows an axonometric view of the new mechanical applied to two different keys of the bass keyboard;

- figure 3 shows a top view of figure 2. Within the scope of such mechanical, in any case it is envisaged that each key of the bass keyboard is connected, by a suitable stem (not shown in the above figure) to a respective lever (10) keyed at the base, along with all the further similar levers, at a respective shaft (11) arranged parallel to the longitudinal axis (X-X) of the casing that supports the keyboard itself. This lever (10) carries on the front and in the proximity of the bottom end thereof, a plate (10a), parallel to the above shaft (11), against which in rest condition, a shaped arm (18) abuts, welded at the base at a turning rod (13) having an axis (Y-Y) inclined relative to the longitudinal axis (X-X) of the casing supporting the bass keyboard. On each of such rods (13) there are welded one or more stems (15a) at the ends of which there are supported respective valves (15) intended for traditionally cooperating with the bass reed holes.

Moreover, it is noted that such stems (15a) exhibit a longitudinal axis (Z-Z) perpendicular to the longitudinal axis (W-W) of the above arm (1?) welded at the same rod (13). To illustrate the operation of such new mechanical, it must be said that upon the

pressure on a key of the bass keyboard, the corresponding lever (10) is pushed forward, according to arrow F.

In such circumstance the above plate (10a) interferes in the same direction with the opposite respective arm (18), which as a consequence causes the rotation of the relevant turning rod (13) about its longitudinal axis (Y-Y).

During such interference between the plate (10a) and the respective arm (18) a sliding is produced between the surfaces in contact with the one or the other; this is because the plate (10a) oscillates inside a plane orthogonal to the longitudinal axis (X-X) of the above casing, whereas the arm (18) oscillates into a plane orthogonal to the axis (Y-Y) of the rod (13), which as mentioned is not parallel to the same axis (X-X) of the casing. In any case the rotation of each rod (13) as a consequence generates the raising, by the respective stem (15a), of the valve (15) which thereby releases the respective reed hole. As soon as the pressure on the key of the bass keyboard stops, the mechanical recover their starting position thanks to the action of the spring (17) associated to the stem (15a) of the valve (15).

This allows saying that in the mechanical according to the finding, the lever oscillation (10) within its own plane orthogonal to the axis (X-X) of the casing corresponds to a concurrent and integral oscillation of the respective valve (15) within another plane orthogonal to the axis (Y-Y) of the above respective rod (13). With special reference to figure 3, it should be further noted that the subject mechanical actually adopt two different packs (Pl, P2) of rods (13) diverging from one another by an angle (2α), of which the first one (Pl) consisting of a series of parallel rods (13) inclined by a same angle (α) relative to the longitudinal axis of the casing (X-X) and the second (P2) consisting of a corresponding series of parallel rods inclined by a same angle (-α) relative to the longitudinal axis itself (X-X).

Thanks to this device, all the valves (15) of the mechanical according to the finding can adopt a stem (15a) of the same length, despite the fact that such valves (15) must cooperate with two different rows of holes of the reed, parallel to each other but arranged at a different distance relative to the keying shaft (11) of the levers (10). Such result was obtained due to the fact that the stems (15a) of the valves (15) that must

cooperate with the farthest reed hole row from the above shaft (11) are attached to the first pack (Pl) of the above turning rods (13), the one that diverges while approaching the same shaft (11).

While the stems (15a) of the valves that must cooperate with the closest reed hole row to the above shaft (11) are attached to the second pack (P2) of the same turning rods

(13), the one that diverges while separating from the same shaft (11).

The fact of using stems (15a) of the same length at all the valves (15) of the mechanical according to the finding is especially advantageous as it ensures that all the same valves

(15) can have a same opening angle, which corresponds to an identical "weight" at the respective actuating buttons provided on the bass keyboard; this is because the resistance of the return springs (17) of the same valves (15) is directly proportional to the above opening angle.

Moreover it is noted that the above rods (13) are seated and guided into special grooves

(13a) made on the support surface of the entire mechanical according to the finding. Finally, it should be said that the annexed drawing shows two different levers (10) associated to the respective mechanical components specified above.