Patent Abstract:
A screwdriver is convenient for changing driver heads. A button is released to drive an arm of the screwdriver in a first position to grasp a fixing portion of the driver head. The button is pressed to drive the arm to rotate from the first position to a second position to deform an elastic member, with the arm releasing the driver head to make the driver head drop out of the handle. Each of the driver head can be easily mounted to the screwdriver, and detached from the screwdriver.

Full Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to screwdrivers, and particularly to a screwdriver with changeable driver head. 
     2. Description of Related Art 
     A conventional screwdriver is integrally formed with a specific driver head, which can be any of many types and sizes. Because types and sizes of screwdrivers are different from one another, a user usually needs to buy many screwdrivers to handle different tasks. It is quite inconvenient to store or carry these screwdrivers. Therefore, a screwdriver with replaceable driver heads sharing one handle was invented. However, to change driver heads, an operator needs to grasp the handle of the screwdriver with one hand, and change the head with the other hand, which can be extremely inconvenient because two hands are required. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a first exemplary embodiment of a screwdriver. 
         FIG. 2  is an exploded, isometric view of the screwdriver of  FIG. 1 . 
         FIG. 3  is a schematic diagram, showing inner parts of the screwdriver of  FIG. 1 . 
         FIG. 4  is a schematic diagram showing inner parts of a second exemplary embodiment of a screwdriver. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , a first exemplary embodiment of a screwdriver  1  includes a handle  2 , a resisting portion  3 , and a driver head  4  mounted to the handle  2 . 
     The driver head  4  includes an elongated main body  44  with a substantially polygonal-shaped cross-section, a substantially annular-shaped fixing portion, such as a fitting groove  42  defined in a first end of the main body  44 , and an operating portion  46  extending from a second end opposite to the first end of the main body  44 . In other embodiments, the fixing portion may be a protrusion or another kind of structure. 
     The handle  2  includes two parts  21 , and a plurality of fastening members  22  for mounting the two parts  21  together. Each part  21  has a substantially semi-circular cross-section, and includes a matching surface to match with the matching surface of the other part  21 , and a curved surface connecting opposite sides of the matching surface. Four screw holes  216  are defined in one part  21  through the matching surface and the curved surface of the part  21 , and four corresponding through holes  217  are defined in the other part  21  through the corresponding matching surface and curved surface. Each part  21  defines two substantially semicircular-shaped slots  211  and  212 , and a slot  214  with a substantially polygonal-shaped cross-section in the matching surface and symmetrically around an axis of the part  21 , extending from top to bottom of the part  21 . A rectangular-shaped slot  213  is defined in the matching surface of the part  21 , and the slot  212  and an upper part of the slot  214  are defined in a bottom of the slot  213 . A radius of the slot  211  is less than a radius of the slot  212 . Two holes  215  are defined in the bottom of the slot  213 , at opposite sides of the slot  212 . 
     The resisting portion  3  includes a button  31 , a substantially coin-shaped resisting member  32 , an elastic member such as a helical spring  33 , and two arms  34 . The button  31  includes a substantially cylindrical-shaped main body  312 , a substantially annular-shaped protrusion  314  formed around a bottom end of the main body  312 . A radius of the protrusion  314  is greater than the radius of the slot  211 , and less than the radius of the slot  212 . A diameter of the resisting member  32  is greater than a diameter of the spring  33 . In one embodiment, the resisting member  32  may be made of wear-resistant material, such as alloy steel material. Each arm  34  includes a slanting connection pole  343 , a stress portion  341  bent from a top end of the connection pole  343 , and a clasp  344  bent from a bottom end of the connection pole  343 , the clasp  344  substantially parallel to the stress portion  341 . Two shafts  342  extend from opposite sides of a junction between the connection pole  343  and the stress portion  341 . 
     Referring to  FIG. 3 , in assembly, the button  31  of the main body  312  is received in the slot  211  of a first part  21 , with the protrusion  314  being received in the slot  212  of the first part  21  and resisting against a top end of the slot  212 . A top end opposite to the protrusion  314  of the button  31  extends out through the slot  211 . Each arm  34  is received in the slot  214  of the first part  21 , with one shaft  342  of the arm  34  inserted into a corresponding hole  215  of the first part  21 . The spring  33  is received in the slot  212  and below the stress portion  341  of the arm  34 , with a bottom end of the spring  33  resisting against a bottom end of the slot  212 . The resisting member  32  is mounted between a top end of the spring  33  and the stress portions  341  of the arms  34 . The two parts  21  are attached, with the matching surfaces of the two parts  21  matching with each other, the corresponding shafts  342  of the arms  34  received in the corresponding holes  215  of the second part  21 , and the through holes  217  of the second part  21  aligning with the corresponding screw holes  216  of the first part  21 . The fastening members  22  extend through the corresponding through holes  217 , to engage in the corresponding screw holes  216 , thereby fixing the two parts  21  together to form the handle  2 . 
     In use, an operator holds the screwdriver  1  in one hand and presses the button  31  of the main body  312 , with the protrusion  314  of the button  31  pressing the stress portions  341  of the arms  34  down. The resisting member  32  compresses the spring  33 , and the arms  34  rotate around the corresponding shafts  342  to make the clasps  344  of the arms depart from each other. Then, while still only needing to use one hand, the operator can fit the slot  214  over a driver head  4  and release the button  31 . The spring  33  then restores and the arms  34  rotate back, with the clasps  344  moving towards each other to sandwich the driver head  4  at the fitting groove  42  of the driver head  4 . Therefore, the screwdriver  1  is assembled with a driver head  4 . 
     When the driver head  4  needs to be detached from the screwdriver  1 , the screwdriver  1  is kept vertical. The button  31  is pressed, the stress portion  341  pushes the resisting member  32  to compress the spring  33 . The arms  34  rotate around the shaft  342 , and the clasps  344  depart from each other to release the driver head  4 . The driver head  4  overcomes friction between a wall bounding the slot  214  and the driver head  4 , to drop from the handle  2  automatically, because of gravity, and then another driver head  4  may be installed as above. 
     When a new driver head  4  needs to be mounted on the screwdriver  1 , the button  31  is pressed to rotate the arms  34 , with the clasps  344  departing from each other. The new driver head  4  which is kept vertical in a toolbox is inserted into the slot  214  of the handle  2 . The button  31  is released, and the spring  33  restores to rotate the arms  34  back. The clasps  344  move towards each other to clasp the driver head  4  at the fitting groove  42 . 
       FIG. 4  discloses a second exemplary embodiment of a screwdriver  1 . A difference between the first and the second exemplary embodiments of the screwdrivers  1  is that the second exemplary embodiment of the screwdriver  1  does not include a resisting member  32  and the spring  33 , while includes a torsion spring  35  connected between each arm  34  and the handle  2 . The torsion springs  35  provide a power to drive the clasps  344  of the arms  34  to clasp the driver head  4  firmly. 
     It is to be understood, however, that even though numerous characteristics and advantages of the embodiments have been set forth in the foregoing description, together with details of the structure and function of the embodiments, the disclosure is illustrative only, and changes may be made in details, especially in matters of shape, size, and arrangement of parts within the principles of the embodiments to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Technology Classification (CPC): 1