Patent Publication Number: US-2006011022-A1

Title: Hand tool having electrified body detection alarm

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a hand tool and more particularly, to a hand tool, such as pliers, adjustable wrench, etc., having electrified body detection alarm.  
      2. Description of the Related Art  
      When using a cutting tool such as pliers to cut off an electric wire, the worker cannot know the electric status of the electric wire from the outer appearance. If the electric wire is electrified, an electric shock may occur during cutting, thereby resulting in an accident When cutting the electrified electric wire with the cutting tool, a short circuit will be produced, and the high temperature of the short circuit may damage the cutting edges of the blades of the cutting tool and causes a fire. If the electrified electric wire carries a big current, a strong flashlight and big explosion will follow the short circuit, causing an injury to the body of the worker.  
      Therefore, it is desirable to provide a hand tool that eliminates the aforesaid problems.  
     SUMMARY OF THE INVENTION  
      The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a hand tool, which detects the electric status of the workpiece and gives a warning signal when the hand tool touching an electrified body, preventing the accident of an electric shock.  
      It is another object of the present invention to provide a hand tool, which has the produced warning signal easy to recognize by the user.  
      To achieve these objects of the present invention, the hand tool comprises a tool body, at least one insulating sheath and an alarm circuit assembly. The tool body is made of electrically conducting material and has a handle and a work head. The insulating sheath is made of electrically insulating material and is covered on the handle of the tool body. Each the insulating sheath has a longitudinal receiving hole for receiving the handle. The alarm circuit assembly comprises a circuit board mounted inside the insulating sheath for detecting electric status of the tool body, a battery set mounted inside the insulating sheath for providing electricity to the circuit board, and an alarm electrically connected to the battery set through the circuit board and controlled by the circuit board to produce an alarm signal upon detection of the presence of electric current at the tool body by the circuit board. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an exploded view of a hand tool according to the first preferred embodiment of the present invention.  
       FIG. 2  illustrates the insulating sheaths respectively fastened to the handles of the rod elements of the tool body according to the first preferred embodiment of the present invention.  
       FIG. 3  is a front view of the hand tool according to the first preferred embodiment of the present invention.  
       FIG. 4  is a left side view of the hand tool according to the first preferred embodiment of the present invention.  
       FIG. 5  is a perspective view of a hand tool according to the second preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring to  FIGS. 1-4 , a hand tool having electrified body detection alarm in accordance with the first preferred embodiment of the present invention is shown comprised of a tool body  10 , two insulating sheaths  20 ,  30 , a light-transmitting member  40 , and an alarm circuit assembly  50 .  
      The tool body  10  is made of an electrically conducting metal material and comprised of two rod elements  14  in mirror symmetry. The rod elements  14  each have a handle  11  at one end, a work head  13 , which is a blade in this embodiment and can be a jaw as shown in  FIG. 5 , at the other end, and a coupling portion  12  connected between the handle  11  and the work head  13 . The coupling portion  12  of one of the rod elements  14  comprises a pivot pin  12 A. The coupling portion  12  of the other of the rod elements  14  comprises a pivot hole  12 B, which receives the pivot pin  12 A. After connection between the pivot pin  12 A and the pivot hole  12 B, the two rod elements  14  can be operated to make a scissors action, thereby causing the work heads  13  to grasp or cut the workpiece.  
      The two insulating sheaths  20 ,  30  are respectively molded from electrically insulating material. The first insulating sheath  20  has a longitudinal receiving hole  21  longitudinally extended to one end thereof for receiving the handle  11  of one rod element  14 , and a finger flange  22  extended around the outer open end of the longitudinal receiving hole  21  for stopping the fingers of the user&#39;s hand holding the first insulating sheath  20  from touching the unsheltered rod elements  14  accidentally. The second insulating sheath  30  has a longitudinal receiving hole  31  longitudinally extended to one end thereof for receiving the handle  11  of the other rod element  14 , a finger flange  32  extended around the outer open end of the longitudinal receiving hole  21  for stopping the fingers of the user&#39;s hand holding the second insulating sheath  30  from touching the unsheltered rod elements  14  accidentally, a first chamber  33  disposed adjacent to the outer open end of the longitudinal receiving hole  21 , and a second chamber  34  formed in the rear end sealed with an end cap  35 . The light-transmitting member  40  is a transparent hollow endless member molded from acrylics or the like that admits light, and fastened to the periphery of the finger flange  32  of the second insulating sheath  30  around the top open end of the longitudinal receiving hole  31 . It is to be understood that the light-transmitting member  40  can be transparent, or have a particular color that attracts attention.  
      The alarm circuit assembly  50  comprises an alarm  51 , a circuit board  52 , electric wires  53 , and a battery set  54 . According to this embodiment, the alarm  51  is a visual alarm formed of a light emitting diode and mounted inside the second insulating sheath  30  corresponding to the light-transmitting member  40 . The circuit board  52  is mounted inside the first chamber  33  and electrically connected with the alarm  51 , having an electronic loop adapted to detect the electric status of the tool body  10  and to control on/off of the alarm  51  subject to the electric status of the tool body  10 . The battery set  54  is comprised of a series of battery cells  541  mounted inside the second chamber  34  and electrically connected to the circuit board  52  by the electric wires  53 .  
      After understanding of the structural features of the hand tool, the operation of the hand tool will now be described hereinafter. During operation, the user holds the sheaths  20 ,  30  with the hands to move the handles  11  of the rod elements  14  relative to each other and to further close/open the work heads (blades or jaws)  13  of the rod elements  14 . When the work heads (blades or jaws)  13  touch an electrified body, for example, an electrified electric wire, the electronic loop of the circuit board  52  of the alarm circuit assembly  50  is induced to drive the visual alarm  51 , thereby causing the alarm  51  to produce a visual alarm signal, for example, red light through the light-transmitting member  40 . Upon presence of the visual alarm signal, the user can immediately stop working, preventing a short circuit to damage the work heads (blades or jaws)  13 . After power supply has been cut off from the workpiece, the user can then proceed with the cutting operation safely. Further, the sheaths  20 ,  30  isolate electric current when the rod elements  14  touch an electrified body, preventing the user from suffering an electric shock accidentally. Further, because the light-transmitting member  40  is a hollow endless member molded from acrylics or the like that admits light, and fastened to the periphery of the finger flange  32  of the second insulating sheath  30  around the top open end of the longitudinal receiving hole  31 , it reflects and refracts light from the alarm  51  in different angles. Therefore, the user can see the light of the alarm  51  from any angle. Further, as an alternate form of the alarm circuit assembly  50 , the alarm  51  can be an audio alarm formed of a buzzer, so that the light-transmitting member can be eliminated.  
       FIG. 5  shows a hand tool, i.e. adjustable wrench, having electrified body detection alarm in accordance with the second embodiment of the present invention. According to this embodiment, the hand tool is comprised of a tool body  60 , an insulating sheath  70 , a light-transmitting member  80 , and an alarm circuit assembly (not shown). This embodiment is substantially similar to the aforesaid first embodiment of the present invention with the exception that the tool body  60  has only one single handle, and one single sheath  70  is used and covered on the handle of the tool body  60 .  
      Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.