Abstract:
A capo has a string press element with an arm and a lever clamp that are coupled to form a clamping opening. The lever clamp has an adjustment end to adjust the size of the clamping opening. A trigger is provided to implement clamping operation. The clamping opening can clamp frets of a guitar. The capo can be quickly and easily deployed by a user single-handed through the trigger during playing the guitar. The capo is formed in a simple and neat profile, and provides a desirable match with performers or female performers to enhance appeal.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a capo for guitars and particularly to a capo that has a snap trigger and adjustable clamp opening to facilitate tune setting. 
     BACKGROUND OF THE INVENTION 
     Capo is mounted onto frets of a guitar to adjust high and low pitches. Refer to  FIGS. 1 and 2  for two types of conventional capos. In  FIG. 1 , a string press bar  1   a  has an extension arm  2   a  connecting to a positioning clamp  3  through a spring  5 . When a handgrip  4  receives a force, the spring  5  can be moved. When in use, a performer needs a greater force to clip the fret, thus is difficult to move to the desired fret or remove therefrom, especially to female users. 
       FIG. 2  illustrates another type of capo designed to overcome the drawback of the aforesaid capo. It has an adjustment screw  6  running through a holding plank  7  and connecting to a positioning clamp  8  to incorporate with a string press bar  1   b  equipped with an extension arm  2   b  to provide desired function. It provides an improvement by turning the screw. However, screw turning involves tedious movement and impairs performance. A capo mentioned above is needed to be set on a desired fret to adjust the high or low pitch. 
     All these show that the conventional techniques still leave a lot of room for improvement. How to make tuning of guitars faster and easier is an issue still pending to be resolved. 
     SUMMARY OF THE INVENTION 
     Therefore, the primary object of the present invention is to provide a capo that can be quickly and easily moved and clamped on the frets of a guitar. 
     To achieve the foregoing object, the capo according to the invention includes a string press element, a trigger and a lever clamp. The string press element has two ends, one is a string press end and the other end extended upwards to form an arm with an action end. The arm has a trigger slot at one side remote from the string press end with two side walls formed thereon. The action end has a first axle hole formed on the two side walls. 
     The trigger is held in the trigger slot, and has a second axle hole pivotally coupled in the trigger slot. The trigger is an elongate plank with an upper end and a lower end. The upper end is a sliding end. The lower end is an operating end. The lever clamp has a clamping end at one end and an adjustment end at another end. The adjustment end is located above the sliding end of the trigger and has a screw hole run through by an adjustment screw. Below the lever clamp has a first trenched axle. The first trenched axle and an elastic element are hinged on the first axle hole. The clamping end and the string press end form a clamping opening. 
     The capo thus formed provides many benefits, notably: 
     1. The first axle hole, sliding end and second axle hole form triangular fulcrums. Incorporating with the lever clamp and a roller, the trigger, lever clamp and the string press element form the clamping opening. Such a design provides labor-saving and easier clamping adjustment regardless different sizes and heights of guitar frets. Through the trigger, performers can easily and quickly move the clipping location on the strings. It helps the performers to get a smoother performance. 
     2. Aside from providing improved practicality, the invention also offers more aesthetic appeal. First, the trigger slot is provided to hold the trigger; second, the first trenched axle allows the lever clamp to be hinged on the first axle hole. Hence the whole profile is neat, elegant and simpler. It is more helpful and appealing to performers. 
     The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying embodiments and drawings. The embodiments serve merely for illustrative purpose and are not the limitation of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a first conventional capo. 
         FIG. 2  is a schematic view of a second conventional capo. 
         FIG. 3  is a side view of the invention. 
         FIG. 4  is sectional side view of the invention. 
         FIG. 5  is an exploded view of the invention. 
         FIG. 6  is a sectional side view of the invention in a use condition. 
         FIG. 7  is a schematic view of another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Please refer to  FIGS. 3 ,  4  and  5 , the present invention provides a capo. It includes a string press element  10 , a trigger  20  and a lever clamp  30 . The string press element  10  has two ends, one is a string press end  11  and the other end extended upwards to form an arm  12  with an action end  121 . The arm  12  has a trigger slot  122  at one side remote from the string press end  11  with two side walls  123 . The action end  121  has a first axle hole  125  formed on the two side walls  123 . 
     The trigger  20  is held in the trigger slot  122 . The trigger slot  122  has a housing space  124  through the two side walls  123 . The trigger  20  is held in the housing space  124 . The trigger  20  is hinged in the trigger slot  122  through a second axle hole  21 . The trigger  20  is an elongate plank with an upper end and a lower end. The upper end is a sliding end  22 . The lower end is an operating end  23 . The sliding end  22  has a roller  24  hinged thereon to facilitate sliding. The operating end  23  is jutting below the string press end  11  to facilitate triggering. 
     The lever clamp  30  has a clamping end  31  and an adjustment end  32 . The adjustment end  32  is located above the sliding end  22  of the trigger  20 , and has a screw hole  33  run through by an adjustment screw  34 . The adjustment end  32  further is coupled with a pressing washer  37  run through by the adjustment screw  34  to form a firm fastening with the screw hole  33 . The lever clamp  30  has a first trenched axle  35  at a lower side. The first trenched axle  35  and an elastic element  36  are hinged on the first axle hole  125 . The clamping end  31  and the string press end  11  jointly form a clamping opening  40 . The string press end  11  and the clamping end  31  have respectively a rubber pad  50  located thereon facing each other. 
     The elastic element  36  is a returning spring with two holding ends  361 . The arm  12  has a first holding spot  126  at one side close to the string press end  11  and below the first axle hole  125 . The lever clamp  30  has a second holding spot  311  located below the clamping end  31 . The first and second holding spots  126  and  311  aim to hold the two holding ends  361  of the elastic element  36 . When the clamping end  31  is moved downwards to do clamping, the second holding spot  311  also stops two detent edges  351  formed on the first trenched axle  35 . 
     The invention further has a butting element  60  with a butting end  61  at one end and a hinge end  62  at the other end. The hinge end  62  is clamped and coupled with the first trenched axle  35  from both sides. The butting end  61  is interposed between the sliding end  22  and the adjustment end  32 . The hinge end  62  further has a second trenched axle  621  narrower than the first trenched axle  35  to be clipped therein. The second trenched axle  621  also is pivotally coupled with the elastic element  36 . The butting end  61  has a leaning surface  611  and a butting surface  612 . The butting surface  612  allows the sliding end  22  to slide thereon. The leaning surface  611  allows the adjustment screw  34  to rest thereon for adjustment. 
     Refer to  FIG. 6  for the invention in use and  FIG. 7  for another embodiment. When in use, the operating end  23  of the trigger  20  is moved away from the arm  12 , the roller  24  of the sliding end  22  slides on the butting surface  612  and enters the housing space  124  of the trigger slot  122 . Through the first trenched axle  35  and the elastic element  36 , the adjustment end  32  and the butting element  60  are moved downwards, and the clamping end  31  is moved upwards. As a result, the clamping opening  40  becomes larger so that the string press element  10  and the clamping end  31  can clamp the frets of a guitar. By adjusting the distance of adjustment screw  34  on the leaning surface  611 , it can be used on the frets of different guitars. The string press end  11  can be either a flat or a curved surface.  FIG. 3  shows the string press end  11  formed with a flat surface for use on frets of classic music guitars, while  FIG. 7  shows the string press end  11  formed with a curved surface for use on frets of folk music guitars. 
     As a conclusion, the invention provides the first axle hole  125 , sliding end  22  and second axle hole  21  that form triangular fulcrums. Incorporating with the lever clamp  30  and roller  24 , the clamping opening  40  can be adjusted easier and simpler to do clamping. Compared with the conventional techniques, it offers a lot of improvements, such as: first, with movements of the string press element  10  and the lever clamp  30 , and the trigger  20 , the clamping opening  40  is formed to provide clamping as desired. Users can easily and quickly move the operating end  23  single-handed with less effort. It greatly helps performers to provide smooth performance. Moreover, the roller  24  at the sliding end  22  can slide easily on the butting surface  612  and reduce wearing of the butting surface  612 . Second, through the butting element  60  and adjustment screw  34 , the clamping opening  40  can be easily adjusted through the lever clamp  30 . Third, when the clamping opening  40  clamps a fret of a guitar, the two detent edges  351  of the first trenched axle  35  are stopped by the first holding spot  126  to prevent too much compression on the elastic element  36  that might cause elastic fatigue or damage of the lever clamp  30 . Fourth, the pressing washer  37  allows the adjustment screw  34  to be fastened firmer that prevents loosening of the adjustment screw  34  caused by sound wave vibration during playing of the guitar. Noise generation also can be reduced. 
     In addition to improvement of practicality, the invention also provides a greater aesthetic appeal. The trigger  20  can be easily held in the trigger slot  122 . The first trenched axle  35  allows the lever clamp  30  to be hinged easily. The whole profile is neat and simpler, and provides an elegant match with performers to enhance appeal.