Abstract:
The present invention describes a simple and effective method and a device for adjusting the tension of the string of a string instrument in which a holding section that is displaceable in or on the mounting block in relation to the latter and on which the first end of the string is attached is displaced by action of a hydraulic medium which is under a preselectable pressure for tightening or relaxing the string.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a national stage of and claims the benefit of priority of International Patent Application No. PCT/EP2005/002850, filed on Mar. 17, 2005, which is relied on and incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a method and a device for adjusting the tension on a string on a string instrument, said string being secured at a first end to a mounting block and at a second end to another mount. 
         [0003]    For correct tuning of string instruments, it is necessary to accurately adjust the tension of the strings which are stretched between two mounting points on these instruments, so that when the string is struck, a standing wave of the correct frequency develops and thus the desired note is generated. 
         [0004]    To this end, the string on a string instrument is usually rigidly secured at one of its two ends while the second end of the string is wound onto a spindle or a similar element and can be tightened or relaxed by winding or unwinding it, to thereby obtain the proper tuning of the string. 
         [0005]    In particular, however, when the string instrument is also to be automatically tunable, i.e., by means of a controller which triggers a drive for changing the string tension on the basis of an actual note detected from a string that has been struck in comparing same with an ideal note, such known possibilities for adjusting the string tension are not always suitable. For example, in the case of a guitar, especially an electric guitar or an electric bass, the so-called tuning mechanisms or the pegs for tightening or relaxing the strings, are arranged on the so-called head of the instrument and thus on a comparatively small portion thereof. Although there are basic possibilities for mounting a motor drive for adjusting the string tension here, it is very difficult or almost impossible to arrange the entire controller for a system for automatic tuning of a guitar or an electric bass on this part of the instrument. To this extent, it is desirable to seek alternative options for adjusting the tension on the string of a string instrument. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    Such an alternative is provided with regard to a method for adjusting the tension on a string of a string instrument that is secured at a first end in a mounting block and at a second end on another mount, whereby a holding section that is displaceable in and/or on the mounting block in relation to the latter, the first end of the string being attached to said holding section, is displaced by the action of a hydraulic medium, which is under a preselectable pressure for tightening or relaxing the string. With regard to a device, a device implementing this goal is characterized by a holding section which is displaceably arranged in and/or on the mounting block in relation thereto and which can be displaced by action of a hydraulic medium which is under a preselectable pressure for tightening or relaxing the string. An advantageous embodiment of the device is characterized in that it has at least one bore in the mounting block with a bore section having an enlarged diameter and a bushing that is displaceable in at least one bore and is arranged so it seals off the hydraulic medium, whereby the bushing has a head with an enlarged outside diameter which corresponds essentially to the diameter of the bore in the section of the bore having the enlarged diameter and a protrusion having an outside diameter that corresponds essentially to the diameter of the remaining bore, whereby a shoulder is provided between the head and the protrusion of the bushing, whereby the head of the bushing is arranged in the bore section having an enlarged diameter and the protrusion of the bushing protrudes into the remaining bore so that a sealed annular space is formed between the shoulder between the head and the protrusion of the bushing and the transition from the bore section with the enlarged diameter to the remaining bore, and whereby at least one line for supplying and remaining hydraulic medium opens into this annular space. 
         [0007]    Another advantageous embodiment of the device is characterized in that a bore section that has an enlarged diameter in comparison with the bore in the remaining section of the bushing is arranged in the head of the bushing. 
         [0008]    A further embodiment of the device is characterized in that the bushing is a bushing made out of a piezoelectric ceramic material, and the bushing is electrically contacted to pick up signals obtained by piezoelectric means. 
         [0009]    Finally, another embodiment of the device has a sensor for detecting an acoustic signal of the vibrating string, a converter for converting the acoustic signal into a digital signal for determining a respective frequency, a comparative unit for comparing the frequency thereby determined with a predetermined frequency, a device for adjusting the tension on at least one string and a controller for controlling the device for the adjusting the tension on at least one string on the basis of a deviation found between the frequency thereby determined and the predetermined frequency, characterized in that the device for adjusting the tension of at least one string is a device. 
         [0010]    According to the present invention, the particular characteristic of the novel method for adjusting the tension on a string of a string instrument and/or the inventive device consists of the fact that instead of using a mechanism for winding the string, it works with a hydraulic medium that is under pressure, e.g., a fluid. This hydraulic medium acts on a holding section to which a first end of the string is applied and displaces this holding section and thus the end of the string secured therein in a mounting block in such a way that the tension on the string changes. 
         [0011]    Use of a hydraulic medium, preferably a fluid, in particular a hydraulic fluid, allows automatic adjustment of the string without using any servomotors. Instead, it is possible to work with a hydraulic fluid in a hydraulic reservoir, for example, to adjust the string tension precisely in a pressure-controlled manner. Such a procedure is especially suitable for use in a device for automatic tuning of a string instrument such as a guitar, whereby the supply and removal of hydraulic medium for increasing and reducing the string tension, respectively, are controlled by a controller, depending on the deviation of the frequency of the note actually generated by the string from a predetermined frequency of an ideal note. 
         [0012]    The bushing to be used according to the present invention in conjunction with the bore into which it is inserted, yields an effect similar to that of a piston in a cylinder, so that it can easily be displaced in the bore in the block by the hydraulic medium and/or in relaxation via the string tension, thereby tightening or relaxing the string. This approach is especially suitable for guitars, in particular electric guitars, and electric basses, where the strings are secured in a mounting block on the body of the instrument, and in the case of electric guitars they are occasionally also secured in a tremolo system block. Such a block usually already has bores into which the strings are introduced at one end, usually with a deflection amounting to approximately 90°. Without any great expenditure, it is possible here to replace a traditional block with a block equipped with the inventive bushings and with bores that have been widened accordingly without causing any drastic change in the instrument. This easily creates the possibility of an “automatic” string adjustment without making any significant change in the instrument itself. 
         [0013]    A further embodiment serves to facilitate the attachment of the string ends in the bushing. For example, in the case of guitars, especially electric guitars, and electric basses, the strings typically have thickened areas, so-called ball ends, on the ends that are attached to the body of the instrument. Then the strings can be secured at these ends in the enlarged section of the bore in the bushing. 
         [0014]    If the bushing is made of a piezoelectric ceramic material, it may advantageously also be utilized as a sound pickup with which the vibrations of the string which is in contact with it there can be picked up and converted into electric signals due to the piezoelectric property of the ceramic. These electric signals may then be magnified directly and used as acoustic signals or they may function as control signals to control MIDI functions, for example. Finally, these signals may also be used to supply information about the frequency of the vibrating string actually detected to the device for automatic tuning of a string instrument, said information then serving to adjust the string to the ideal frequency and finally to calculate the required additional tension and/or relaxation of the string. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0015]    Additional features and advantages of the invention are derived from the exemplary embodiment which is described below on the basis of the accompanying figures. The present invention is described in the following description and is illustrated in the figures on the basis of an implementation of an electric guitar, whereby the invention is essentially not limited to this particular string instrument but instead may be applied in principle to all known string instruments. In the figures: 
           [0016]      FIG. 1  shows schematically a view of an electric guitar as an example of a string instrument with a device according to this invention, 
           [0017]      FIG. 2  shows an enlarged schematic diagram of the body of the electric guitar from  FIG. 1 , 
           [0018]      FIGS. 3   a - d  show various views of a tremolo system block equipped according to this invention as part of the guitar illustrated in  FIG. 1  and  FIG. 2 , 
           [0019]      FIG. 4  shows a tremolo system block as shown in  FIG. 3  with attached sliders, one of the sliders being shown in an exploded diagram, and 
           [0020]      FIG. 5  shows a detail of a guitar body with the tremolo system block attached and held by tension springs. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]    The figures show an embodiment of an inventive device on an electric guitar. The same elements are labeled with the same reference numerals. 
         [0022]    First,  FIGS. 1 and 2  show an electric guitar  1  in general. It can be roughly subdivided into a body  2 , a neck  3  and a head  4 . A tremolo system block  5  mounted as a mounting block on the body  2  of this electric guitar  1  embodies the present invention and therefore will be described in greater detail below. 
         [0023]    The strings  6   a  through  6   f  extend from the tremolo system block  5  and are wound onto pegs  7  on the head  4 , where the pegs  7  can be adjusted by thumbscrews  8 . A pickguard  9  is arranged on the body  2  of the electric guitar  1  beneath the strings  6   a  through  6   f.    
         [0024]      FIG. 2  shows the body  2  of the electric guitar  1  on an enlarged scale. In addition, this also shows a control chip  10 , which is to be explained in greater detail below, and a so-called [sound] pickup  12 . Furthermore, this also shows lines  14  by which the control chip  10  is connected to the tremolo system block  5 ; this connection will be described in greater detail below. 
         [0025]      FIGS. 3   a  through d show the tremolo system block  5  in various views in greater detail. This tremolo system block  5  embodies the present invention. In  FIG. 3   a  the tremolo system block  5  is shown in a three-dimensional view; in  FIG. 3   b  it is shown in a view from above; in  FIG. 3   c  it is shown in a sectional view along sectional line A-A from  FIG. 3   b;  and in  FIG. 3   d  it is shown in a sectional diagram along sectional line B-B from  FIG. 3   d  [sic;  3   b].    
         [0026]      FIGS. 3   a  through  3   d  show that the tremolo system block  5  has a total of six bores  11  in which strings  6   a  through  6   f  can be secured by a method described in greater detail below. In a section at the bottom of  FIG. 3   c,  the bores  11  have a section  11   a  with an enlarged diameter. Bushings  13  are arranged in the bores  11  so that they are longitudinally displaceable. Each bushing  13  has an enlarged head  13   a.  The outside diameter of the enlarged head  13   a  corresponds to the inside diameter of section  11   a  of the bore  11 ; the outside diameter of the remaining bushing  13  corresponds to the diameter of remaining bore  11 . In this way, an annular space  17  is formed between the transition of the enlarged head  13   a  to the remaining bushing  13  and the section  11   a  of the bore  11  to the remaining bore  11 . A feed line  18  in the form of a stub bore opens into this annular space  17 . Through this feed line  18  a hydraulic medium can be introduced into the annular space  17 ; in the preferred exemplary embodiment, this hydraulic medium is a hydraulic fluid. 
         [0027]    An inner bore  19  provided in the bushing  13  has an enlarged inside diameter (section  19   a ) in the area of the enlarged head  13   a  of the bushing  13 . Additional bushings  20  (which are not relevant for the present invention but are used for other reasons) can also be seen, these bushings sitting tightly in the bores  11  on the section of the tremolo system block  5  shown at the top of  FIG. 3   c.  These bushings serve to insulate the strings which pass through the bushings  13  from the metal material of the tremolo system block  5 . This insulation is necessary in certain applications, in particular when the strings  6   a  through  6   f  are to be used as electric conductors. When in use, strings  6   a  through  6   f  are secured at one end (the so-called ball end) in the enlarged section  19   a  of the bore in the bushing  13 . The strings are then passed further through the bore  19  in the respective bushing  13  and then through the additional stationary bushing  20  and out of the tremolo system block  5  where they are guided over sliders  21 , which are shown in  FIG. 4  and from there over the neck  3  to the head  4  of the electric guitar  1 , where they are wound onto the pegs  7 . The bushings  13  and the bores  11  in the tremolo system block  5  are held in their position by hydraulic fluid in the annular space  17 . The pressure of the hydraulic fluid exerted on the bushing  13  is in equilibrium with the force exerted by the string and/or its tension. If the string is to be tightened, then additional hydraulic fluid is introduced into the annular space  17  through the feed line  18  to increase the pressure. This causes the bushing  13  to move downward in the bore  11  in the alignment illustrated in  FIG. 3   c  and therefore the string is put under tension. In the converse case, if the string is to be relaxed, hydraulic fluid is drained out of the feed line  18 , so the bushing  13  is moved upward in the bore  11  in the orientation shown in  FIG. 3   c.    
         [0028]    Hydraulic fluid from a hydraulic fluid storage element is preferred, this hydraulic fluid storage element can readily be arranged in the body  2  of the guitar  1  in particular without altering the geometry and/or the material of the guitar and therefore without milling or other material recesses. This requires only a corresponding valve switching, which is correctly triggered for tightening or relaxing the guitar strings in each case. 
         [0029]    As an alternative to the operation of the device described here, it may also include a unit (dual-chamber system) that can be acted upon with hydraulic fluid in both directions, i.e., for tightening as well as relaxing the strings. 
         [0030]    In the exemplary embodiment depicted here, it is important that the total length of the bushing  13  is longer than the length of the enlarged section  11   a  of the bore  11  so that here the annular space  17  is sealed with respect to the remaining bore  11  even in the condition of maximum string tension, and no hydraulic fluid can escape in an uncontrolled manner from the annular space  17 . 
         [0031]    In a preferred application, this system for adjusting the tension on the strings is integrated into a device for automatic tuning of the guitar. To do so, the control chip  10  shown in  FIG. 2  is used. In this chip, an ideal value for the frequency of a basic vibration of each spring is stored. This control chip  10  is connected to sound pickups  12 , for example, via signal lines to be able to detect the current frequency of the basic vibration of the strings. From the difference between the ideal value and the actual value, the control chip  10  calculates a measure by which the respective string is to be tightened or relaxed and controls the valve for the feeder line  18  assigned to this string accordingly, so that the respective adjustment of the string tension of the respective string can be performed by supplying or draining off the hydraulic fluid. 
         [0032]    Instead of using the sound pickups  12  (electromagnetic pickups), piezoelectric elements introduced separately into the tremolo system block  5  or the bushings  13  themselves if they are made of a piezoelectric ceramic material may be used as the element for detecting the actual values of the frequency of the string. 
         [0033]    Finally,  FIG. 5  shows a detail from the body  2  of the electric guitar  1  as seen from the rear and/or from the bottom. The suspension of the tremolo system block  5  here which is equipped with the bushings  13  that operate according to the present invention can be seen in this figure. The tremolo system block  5  is held in balance with the help of three springs  22  which can be adjusted in their tension acting on the tremolo system block  5  by means of corresponding adjusting devices  23 . This yields another possible use of the hydraulic adjustment. As part of a technical development that can be utilized independently of the present invention, it is conceivable for the spring tension of the individual springs holding the tremolo system block  5  in balance to be varied by means of hydraulic or pneumatic cylinders or in some other way activated by using hydraulic medium. In this way, an adjustment of the balance of the tremolo system block could be performed “automatically,” e.g., to achieve different effects of playing the guitar or to adapt the tensile forces when using different tremolo systems, e.g., a Floyd Rose tremolo system. Such a cylinder is labeled here as  24 . For example, it is also possible to replace the springs  22  as a whole by pneumatic cylinders and/or hydraulic cylinders. The latter approach can also be implemented independently of the invention claimed here and constitutes a separate invention by itself. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 List of Reference Numerals 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                  1 
                 electric guitar 
               
               
                   
                  2 
                 body 
               
               
                   
                  3 
                 neck 
               
               
                   
                  4 
                 head 
               
               
                   
                  5 
                 tremolo system block 
               
               
                   
                  6a-f 
                 string 
               
               
                   
                  7 
                 peg 
               
               
                   
                  8 
                 thumbscrew 
               
               
                   
                  9 
                 pickguard 
               
               
                   
                 10 
                 control chip 
               
               
                   
                 11 
                 bore 
               
               
                   
                 11a 
                 enlarged section 
               
               
                   
                 12 
                 sound pickup 
               
               
                   
                 13 
                 bushing 
               
               
                   
                 13a 
                 enlarged head 
               
               
                   
                 14 
                 line 
               
               
                   
                 17 
                 annular space 
               
               
                   
                 18 
                 feed line 
               
               
                   
                 19 
                 bore 
               
               
                   
                 19a 
                 section 
               
               
                   
                 20 
                 bushing 
               
               
                   
                 21 
                 slider 
               
               
                   
                 22 
                 spring 
               
               
                   
                 23 
                 adjusting device 
               
               
                   
                 24 
                 pneumatic cylinder or 
               
               
                   
                   
                 hydraulic cylinder