Abstract:
An over-current protector comprised of multiple over-current protection devices each at various switching temperature and provided with positive temperature coefficient; all devices being stacked and segregated with an reinforced insulation layer and connected in parallel through a conducting mechanism each respectively provided at where in relation to both ends of the device; both conducting mechanisms constituting the terminal electrodes of the over-current protector as a whole for reducing initial resistance, increasing peak resistance, and in turn upgrading voltage withstanding performance.

Description:
BACKGROUND OF THE INVENTION 
   (a) Field of the Invention 
   The present invention is related to an over-current protector, and more particularly to one that reduces initial resistance, increase peak resistance, and upgrade high voltage withstanding performance. 
   (b) Description of the Prior Art 
   Being compact and multi-purpose dominate the design in consumer electronic products today including the handset, Notebook, digital camera (video camera), and PDA. Similarly, the high-efficacy and compact electric installations are demanded for providing good circuit configuration, assurance of normal operation of the entire electric circuitry, and prevention of shortage due to over-current, or over-temperature to the secondary battery or the circuit device. 
   Therefore, the design of over-current protection circuit has to meet the requirements of high-efficacy and compactness. Over-current protection devices generally available in the market are usually built up with positive temperature coefficient (PTC). They feature lower resistance at low temperature to permit smooth flow of current, and when the electric installation heats up, its temperature rises to a certain, critical temperature, the resistance would drastically increase up to several tens of thousand folds to achieve its purpose of protecting the battery or the circuit device. 
   However, in practical use, conducting filling material is reduced to increase peak resistance in response to the characteristic of energy consumption; in turn, the initial resistance is also increased to compromise its conductivity. 
   SUMMARY OF THE INVENTION 
   The primary purpose of the present invention is to provide a multi-layer over-current protector that reduces initial resistance, increase peak resistance, and upgrade voltage-withstanding performance. To achieve the purpose, the present invention is comprised of multiple over-current protection devices stacked and segregated with a reinforced insulation layer, two conducting mechanisms are respectively provided on the insulation layer at where in relation to both ends of each over-current protection device to connect all the over-current protection device in parallel, and to become the terminal electrode for the entire over-current protector. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a sectional view of a first preferred embodiment of the present invention. 
       FIG. 2  is a schematic view showing the flow of the current in the first preferred embodiment of the present invention. 
       FIG. 3  is a sectional view of a second preferred embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , a preferred embodiment of the present invention has two over-lapped protection devices  10 ,  10  stacked to each other. The over-current protection device may be of the so-called thermistor device. Both devices  10 ,  10  are made of different polymers (e.g., polyolefin polymer or epoxy) and different conducting fillings (e.g., carbon black, metal powder and ceramic powder) so to make both over-current protection devices  10 ,  10  to have different switching temperatures. Both over-current protection devices  10 ,  10  are segregated by an reinforced insulation layer  20 , and a conducting mechanism  31  is each provided to the insulation layer  20  at where in relation to both ends of the over-current protection devices  10 ,  10  so to connect both over-current protection devices  10 ,  10  in parallel. Both conducting mechanisms  31  constitute the terminal electrode for the entire over-current protector that reduces initial resistance, increases peak resistance, and in turn upgrades voltage-withstanding performance. 
   In the first preferred embodiment, a first and a second conducting layers  32 ,  32  are provided at where the reinforced insulation layer  20  is attached to both of the over-current protection devices  10 ,  10 . A first electrode layer  33  respectively connected to the conducting mechanism  31  is provided at where between the upper over-current protection device  10  and an insulation layer  60  provided on top of the over-current protection device  10 . The first electrode layer  33  is comprised of two parts, respectively, a first member  331  of the first electrode layer  33  and a second member  332  of the first electrode layer  33 . A second electrode layer  34  respectively connected to the conducting mechanism  31  is provided at where between the lower over-current protection device  10  and an insulation layer  60  provided on the bottom of the over-current protection device  10 . The second electrode layer  34  is comprised of two parts, respectively, a first member  341  of the second electrode layer  34  and a second member  342  of the second electrode layer  34 . One terminal electrode  35  is each respectively provided to the first and the second members  331 ,  332  of the first electrode layer  33  as well as the first and the second members  341 ,  342  of the second electrode layer  34  to create a parallel circuit as illustrated in  FIG. 1 . 
   As illustrated in  FIG. 2 , the current enters from the terminal electrode  35  at the first member  341  of the second electrode layer  34  flows first through the conducting mechanism  31  at one end, then respectively through the first member  331  of the first electrode layer  33  and the first member  341  of the second electrode layer  34  into the upper and the lower over-current protection devices  10 ,  10  into the first and the second conducting layer  32 ,  32  then returning into the upper and the lower over-current protection devices  10 ,  10  from there, the current respectively flows through the second member  332  of the first electrode layer  33  and the second member  342  of the second electrode layer  34 ; at last, jointly flowing through the conducting mechanism  31  provided on the other end to exit from the terminal electrode  35  disposed at the second member  342  of the second electrode layer  34  to complete an integral cycle of a parallel circuit. 
   As illustrated in  FIG. 3  for a second preferred embodiment of the present invention, the construction of the entire over-current protector has respectively provided a first and a second conducting parts  411 ,  412  of a first conducting layer  41 , and a first and a second conducting parts  431 ,  432  of a third conducting layer  43  at where between both over-current protection devices  10 ,  10  are attached to the reinforced insulation layer  20 , a first and a second conducting parts  421 , 422  of a second conducting layer  42  disposed between both reinforced insulation layers  20 . The first and the second conducting parts  411 ,  412  of the first conducting layer  41  as well as the first and the second conducting parts  431 ,  432  of the third conducting layer  43  disposed between both over-current protection devices  10 ,  10  do not physically contact with both conduction mechanisms  31  provided on both sides of the over-current protector. Instead a conducting device  50  is provided to connect each of the conducting layers disposed between both over-current protection devices  10 ,  10 . The first and the second conducting parts  421   422  of the second conducting layer  42  disposed between both reinforced insulation layers  20  have physical contact with both conducting mechanisms  31  on both sides of the over-current protector. 
   Similarly, the first electrode layer  33  respectively connected to both conducting mechanisms  31  is provided at where between the upper over-current protection device  10  and an insulation layer  60  is provided on the top of the upper over-current protection device  10 . The first electrode layer  33  includes two separately provided first and second members  331 ,  332  while the second electrode layer  34  respectively connected to both conducting mechanisms  31  is provided at where between the lower over-current protection device  10  and an insulation layer  60  is provided on the bottom of the lower over-current protection device  10  The second electro layer  34  includes two separately provided second electrode layer  34  includes two separately provided first and second 3  members  341 ,  342 . Two terminal electrode  35  are respectively provided to the first and the second members  331 ,  332  of the first electrode layer  33  as well as the first and the second members  341 ,  342  of the second electrode layer  34  to create the parallel circuit as illustrated in  FIG. 3 . The present invention by providing multiple over-current protection devices of the same resistance but at different switching temperatures connected in parallel to reduce initial resistance, increase peak resistance, and in turn upgrade voltage-withstanding performance. 
   The present invention provides an improved structure of an over-current protector; therefore, this application for a utility patent is duly filed accordingly. However, it is to be noted that the preferred embodiments disclosed in the specification and the accompanying drawings are not limiting the present invention; and that any construction, installation, or characteristics that is same or similar to that of the present invention should fall within the scope of the purposes and claims of the present invention.