Abstract:
A screwdriver is convenient for changing various heads. The heads can be easily detached from the screwdriver, and mounted to the screwdriver.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to screwdrivers, and particularly to a screwdriver changeable head. 
     2. Description of Related Art 
     Generally, screwdrivers are integrally formed with a specific head, such as slotted or Phillips head. Because there are many types and sizes of screws, a user usually needs to buy many different screwdrivers for all their needs, which is inconvenient. Therefore, a screwdriver with replaceable heads was invented. However, many conventional replaceable heads are easily disengaged from the screwdriver, thereby making operation of the screwdriver inconvenient and time-consuming. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded, isometric view of an exemplary embodiment of a screwdriver. 
         FIG. 2  is an enlarged, isometric view of a head of the screwdriver of  FIG. 1 . 
         FIG. 3  is a cutaway, isometric view of  FIG. 2 . 
         FIG. 4  is an exploded, isometric view of  FIG. 3 . 
         FIG. 5  is an enlarged, isometric view of an elastic member of  FIG. 4 . 
         FIG. 6  is an assembled, isometric view of  FIG. 1 . 
         FIG. 7  is a cutaway, isometric view of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , an exemplary embodiment of a screwdriver includes a handle  1  and a plurality of types of heads  2  capable of being sequentially attached to the handle  1 . 
     Referring to  FIGS. 2 to 6 , each head  2  includes a cylindrical holder  22 , a prismatic shank  24 , and a blade  26  sequentially and integrally formed. An annular slot  242  is defined in an outside circumferential surface of the shank  24  adjacent to the blade  26 . 
     The holder  22  includes an external first sleeve  222  with a cylindrical configuration, an internal second sleeve  224  with a prismatic configuration, and a plurality of elastic tabs  23  attached to the second sleeve  224 . A space  227  is defined between the first sleeve  222  and the second sleeve  224 , to receive the elastic tabs  23 . The first sleeve  222  and the second sleeve  224  are co-axial. The second sleeve  224  includes a plurality of walls  2240  connected to each other at corresponding adjacent edges. Each of the walls  2240  includes a projection  2242  extending from an inside surface thereof and toward the first sleeve  222 , and a round through hole  2244  located beside the projection  2242 . The projection  2242  has a T-shaped cross-section. Each of the elastic tabs  23  includes a through hole  232  defined in one end thereof, and a semi-spherical shaped protrusion  234  extending from the other end thereof. The through hole  232  is capable of fixing around the projection  2242  of the second sleeve  242  and the protrusion  234  is capable of engaging in the through hole  2244  of the second sleeve  242  and extending out from the wall  2240 , to attach the elastic tab  23  to the inside surface of the second sleeve  242 . A label  228  indicating the type of the head  2  is formed on an outside surface of the first sleeve  222 . In this embodiment, the label  228  is “+”, indicating a crosshead type. In other embodiments, the label  228  may include numbers, for example, “+10” indicating that the head  2  is a No. 10 crosshead type. 
     Referring to  FIG. 7 , the handle  1  includes a cylindrical grabbing portion  12 , and a prismatic shaft  14  integrally extending from one end of the grabbing portion  12 , and a blade  16  integrally extending from a free end of the shaft  14 . The shaft  14  and the blade  16  are similar to the shank  24  and the blade  26  of the head  2 . An annular slot  142  is defined in an outside circumferential surface of the shaft  14  adjacent to the blade  16 . In other embodiments, the shaft  14  can be mounted to the grabbing portion  12 . 
     Referring to  FIGS. 6 and 7 , in assembly of the heads  2 , the shank  24  of a first head  2  is slidably inserted into the holder  22  of a second head  2 . The elastic tabs  23  of the second head  2  are deformed and then rebound, and the protrusions  234  of the second head  2  engage in the annular slot  242  of the shank  24  of the first head  2 . In assembly of the heads  2  and the handle  1 , the shaft  14  of the handle  1  is inserted into the holder  22  of the corresponding head  2 , with protrusions  234  of the corresponding head  2  engaging in the annular slot  142  of the handle  1 . 
     In use, various types of heads  2  can be quickly selected by observing the labels  228  on the heads  2 . A selected head  2  can be mounted directly to the shaft  14  of the screwdriver or over another head  2  that is already mounted on the shaft  14  securely without easily disengaging unless a purposeful pulling force is applied by a user. 
     In other embodiments, the screwdriver can be an electric screwdriver. The label  228  can be formed on other positions of the holder  22  to facilitate identification of the types of the head  2 . 
     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.