Briccialdi B flat thumb key mechanism for a woodwind instrument
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a thumb double key, commonly called a Briccialdi B/B flat mechanism, in other words a mechanism operating the tones B and B flat, for a woodwind instrument, such as a flute or piccolo. Such a mechanism comprises a B key comprising a cup part and a lever part, the B key being rockingly movable around an axle, and a lever rockingly movable around the same axle and capable of transferring the rocking motion to the B key so as to close the B key and at the same time to a B flat key so as to close the B flat key. 
     2. Description of the Prior Art 
     The known Briccialdi B/B flat thumb key or lever mechanism is designed such that the rocking motion of the double key takes place by means of two charnier tubes mounted on an axle which is arranged at right angles to the longitudinal axis of the instrument. 
     The transmission of the rocking motion of the double key to the B-flat key on the main axle is effected by means of a simple system of levers between the back-connecting levers of the said keys. 
     The Briccialdi B flat thumb key mechanism consists of the two levers arranged parallelly at right angles to the above-mentioned longitudinal axle. The B key function applies to one of the levers. The other lever arranged above the B key but on the same axle acts such that any pressure on this lever causes a simultaneous closure of the B flat key on the main axle by means of the above-mentioned back-connecting levers. The springs of the mechanism are flat springs attached to the levers. The flat springs are arranged in the longitudinal direction of the levers and slide on the surface of the instrument tube which is normally made of a noble metal. The pressure exerted by the springs on the tube determines how fast the rocking motion of the levers can get. 
     This known design incurs a number of disadvantages, especially friction, less than optimal stability and slackness in the function of the key. Thus, the geometrical conformation of the flat springs attached to the levers is not optimal to their purpose, and it is known that there can be significant friction between the ends of the springs and the surface of the instrument tube on which they slide. This non-optimal conformation with a sliding movement and the friction caused hereby therefore limit how fast the rocking motion of the levers can get and thereby limit the artistic freedom of the musician. Furthermore, the difference in the action between the flat springs of the conventional Briccialdi double key and the needle springs used at all other keys gives an undesired difference in the tactile action between the Briccialdi keys and all other keys and thereby an unevenness in the tactile feel of the instrument as a whole. 
     SUMMARY OF THE INVENTION 
     The present invention avoids the above disadvantages and provides further important improvement, resulting in a more suitable and durable and more harmonious instrument having a higher degree of adaption to the anatomy of the human hand. 
     The B/B flat mechanism according to the invention is of the above-discussed Briccialdi type having a B key (2) comprising a cup part and a lever part, the B key being rockingly movable around an axle (1), and a lever (3) rockingly movable around the same axle (1) and capable of transferring the rocking motion to the B key so as to close the B key and at the same time to a B flat key so as to close the B flat key, and it is characterized in that the axle (1) defines an angle of 20°-75° relative to the longitudinal axis of the instrument. 
     The angle is normally in the interval of 30°-70°, preferably 40°-60°, relative to the longitudinal axis of the instrument. The fact that the thumb key axle defines the above-mentioned angle with the longitudinal axis of the middle piece makes it possible to obtain an almost double length of the charnier tubes compared to the conventional arrangement, thereby very considerably stabilizing the rocking motion against slack or play. Another important advantage is that the rocking rotation of the key and the lever around the axle will have a considerable component in the longitudinal direction of the instrument, thereby having an action which is closer to the action of the other keys of the instrument which all rotate around an axis substantially parallel to the axis of the instrument. This also makes the interaction between the musician&#39;s thumb and the key much more harmonious from an anatomic point of view compared to the conventional mechanism where the rotation is strictly perpendicular to the longitudinal axis of the instrument. 
     At the same time, the increased length of the charniers made possible because of the angle permits the use of needle springs instead of flat springs, thereby eliminating the above-mentioned problems with friction and unsuitable spring conformation and providing a faster action and an action which is of the same tactile feel as the action of the other keys of the instrument, thereby greatly contributing to harmony of the instrument. 
     The fact that the two charnier tubes of the levers can be considerably longer than in the conventional construction results in a longer support surface and thereby increased stability and reduced wear of the mechanism. 
     A very interesting interval of the above-mentioned angle is 47° to 57°, e.g. about 52°, as this provides optimum passages for needle springs. Instruments built with such angles have been found to have a superior function from all points of view. 
     In conformity with normal design of the Briccialdi mechanism, the B flat key in the mechanism according to the invention is suitably arranged on the main longitudinal axle of the instrument, and the rocking movement is transferred from the lever to the B flat key via a lever arranged on the main longitudinal axle of the instrument. Also, the lever arranged above the B key is suitably is arranged substantially parallel to the longitudinal direction of the instrument and to the lever part of the B key. 
     A further advantage with respect to the stability of the mechanism of the instrument is obtained when the thumb key axle is arranged so that it fixes the trill key axle (4) of the instrument, e.g. by means of its thread. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following, a B/B flat mechanism for a flute or piccolo according to the invention is described with reference to the drawings in which 
     FIG. 1 shows a mechanism with a construction principle according to the present invention, 
     FIG. 2 shows essential parts of the characteristic embodiment of the mechanism of the invention, 
     FIG. 3 shows a B key; 
     FIG. 4 shows a B flat lever; and 
     FIG. 5 shows fixation of the trill key axle with a thumb key axle according to another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The mechanism shown in the drawings consists of a diagonally arranged B/B flat key axle (1) in FIG. 1, with a lever 2b of the B key 2 and the B flat lever 3 mounted on the axle (1) by means of charniers 1a and 1b, respectively. 5 and 5a designate catches for needle springs. 6 designates the main axle of the instrument, carrying a lever 3a which is actuated by the lever 3. 4 designates the ends of a trill axle of the instrument. 
     In operation, the B key 2 (designated H) is closed by depressing the lever 2b. The charnier 1a of the lever 2b of the B key 2 will thereby rock (rotate) around the axle 1. Due to the relatively great length of the charnier, the movement will be smooth and stable. The charnier is spring-loaded by means of a needle spring (not shown in FIG. 1, but apparent as 8 in FIG. 2) one end of which engages with the catch 5a. The lever 3, when depressed, will transfer its movement to a cup 2a of the key 2, thereby closing the B key 2. At the same time, the lever 3 will actuate the closure of the B flat key 7, designated B, through a lever 3a attached to the main longitudinal axle of the instrument. 
     FIG. 2 shows a detail of the mechanism in enlarged scale. 9 designates an exterior post 9 of the axle 1, and 10 designates in inner post 10 fixing the axle 1 and at the same time fixing the trill key axle 4 through its thread 11. Needles 8 and 8a are mounted in the interior post 10 and the exterior post 9 (as shown at 9a) respectively. 
     FIGS. 3 and 4 show the B key and the B lever separately. 
     FIG. 5 shows the fixation of the trill axle 4 with the flat key axle 1 according to another embodiment of the invention.