Patent Publication Number: US-8111127-B1

Title: Thermistor

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a thermistor; in particular, to a thermistor capable of being fixed to a printed circuit board firmly. 
     2. Description of the Related Art 
     Based on temperature change, the resistance of a thermistor changes accordingly. With high sensitivity, accuracy and stability, the thermistor is widely used as a sensor in measuring, compensating, and controls. Industrial applications include consumer electronic products, automobiles, medical instruments, food processing, communication and instrumentation, military equipments, aerospace, and research &amp; development areas. 
     When mounting the thermistor onto the printed circuit board, the conventional procedure involves connecting both electric plugs of the thermistor into the pre-cut slots on the circuit board. Next, the assembly is transferred to a tin soldering furnace, where the electric plugs are soldered onto the printed circuit board. To prevent damaging the thermistor due to external forces or falling off from the printed circuit board, glue is added manually between the thermistor and the printed circuit board. Several disadvantages are associated with the above practice. First, not all thermistor may be glued properly. Second, the glue may peel off. Thirdly, manual effort and time are wasted in the process. 
     To solve the above problems, the inventor proposed a new thermistor based on past research and expertise. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a thermistor that connects to a metallic fixing piece. The fixing piece is designated for soldering onto the printed circuit board, thereby anchoring the thermistor to the printed circuit board more securely. 
     To achieve the aforementioned object, the present invention provides a thermistor including: a main body; two electric plugs located on one end of the main body; a metallic fixing piece placed on the side of the main body. The metallic fixing piece has a connecting portion with one side of the main body, and a soldering portion at the other end of the main body. The soldering location is opposite to the electric plugs and protrudes from the main body. The other component is a cover, which is over the main body and the fixing piece&#39;s connecting location. Providing a snug fit, the cover ensures the metallic fixing piece is firmly attached to the main body. 
     The cover is temperature dependent and acts as a heat shrink sleeve. 
     The present invention has several advantages. First, the metallic fixing piece can be soldered onto the printed circuit board, thus allowing the thermistor to be attached more firmly. If under vibrations due to external forces, the thermistor is less likely to suffer damages or falls off the printed circuit board. Second, the thermistor&#39;s electric plugs and the soldering portion of the metallic fixing piece can be soldered onto the printed circuit board with only one soldering process. Thus, manual glue dispensing is not needed, thereby eliminating the material cost of the glue, simplifying the manufacturing process and shortening the production time. Consequently, the overall manufacturing cost is reduced. 
     For reference, detailed explanation and illustrations are included below for the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an exploded view of the thermistor. 
         FIG. 2  shows an exploded view of the thermistor from another angle; 
         FIG. 3  shows an assembled view of the thermistor. 
         FIG. 4  is a cross-sectional view of line  4 - 4  in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The aforementioned illustrations and following detailed descriptions are exemplary for the purpose of further explaining the scope of the present invention. Other objectives and advantages related to the present invention will be illustrated in the subsequent descriptions and appended drawings. 
     Please refer to  FIG. 1˜3 . The present invention provides a thermistor including a main body  10 , two electric plugs  20 , a metallic fixing piece  30 , and a cover  40 . 
     The two electric plugs  20  are located on one end of the main body  10  and electrically connected to the main body  10 . The two electric plugs  20  have different polarities from each other, with equal or different lengths. The electric plugs  20  are connected mechanically and electrically to the slots in the printed circuit board (not shown in picture). 
     The metallic fixing piece  30  is located on one side of the main body  10 , with a connecting portion  31  and a soldering portion  32 . The shape of the connecting portion  31  substantially corresponds to that of the main body  10 , with the connecting portion  31  laying against one side of the main body  10 . The soldering portion  32  is narrower than the connecting portion  31 , but it is not limited thereto. The soldering portion  32  is located on the other end of the main body  10 , opposite to the electric plugs  20  and protrudes from the main body  10 . In other words, the soldering portion  32  and the electric plugs  20  are located on two opposite ends of the main body  10 . Furthermore, the material selection for the metallic fixing piece  30  is open for selection. The suggested choice is tin plate. 
     The cover  40  is over the main body  10  and the connecting portion  31  of the metallic fixing piece  30 , thereby holding the metallic fixing piece  30  securely to one side of the main body  10 . With such arrangement, the thermistor of the present invention is assembled accordingly. 
     More specifically, in the present embodiment, the metallic fixing piece  30  is located on the bottom surface of the main body  10 . The upper surface of the connecting portion  31  lays against the bottom surface of the main boy  10  for supporting the main body  10  upwards. The soldering portion  32  is formed by bending and extending downwards from one end of the connecting portion  31  away from the electric plugs  20 . 
     Furthermore, in the present embodiment, the cover  40  is a heat shrink sleeve. When mounting the metallic fixing piece  30 , the heat shrink sleeve of desired length surrounds the main body  10  and the connecting portion  31  of the metallic fixing piece  30 . Next, by blowing hot air, the heat shrink sleeve shrinks and snugs the main body  10  with the connecting portion  31  of the metallic fixing piece  30 . 
     When mounting the thermistor, the electric plugs  20  and the soldering portion  32  of the metallic fixing piece  30  are connected mechanically to predetermined slots on the printed circuit board. Next, the printed circuit board and the thermistor are transferred into a soldering furnace. The electric plugs  20  and the soldering portion  32  of the metallic fixing piece  30  are then soldered onto the printed circuit board, thereby firmly securing the thermistor. 
     Per  FIG. 1˜4 , the cover  40  has a first opening  41  for the electric plugs  20 , along with a second opening  42  at the soldering portion  32  of the metallic fixing piece  30 . Such arrangement allows the electric plugs  20  and the soldering portion  32  of the metallic fixing piece  30  be exposed to the outside of the cover  40 . 
     In summary, the thermistor of the present invention has two electric plugs located on one end of the main body and soldered to the printed circuit board. A cover is used to hold the metallic fixing piece to one side of the main body. The soldering portion of the metallic fixing piece is located on the other end of the main body, opposite to the electric plugs. The soldering portion of the metallic fixing piece is soldered onto the printed circuit board, thereby connecting the thermistor to the printed circuit board more firmly than before. Even when the thermistor is subjected to vibration or swing due to external forces, the thermistor is not likely to be damaged or falls off from the printed circuit board 
     Inside the furnace, both the thermistor&#39;s electric plugs and the soldering portion of the metallic fixing piece can be soldered to the printed circuit board in mere one soldering process. As a result, manual glue dispensing is no longer needed, thereby eliminating the glue cost, simplifying the manufacturing process, shortening the production time, and reducing the overall manufacturing cost. 
     The descriptions illustrated supra set forth simply the preferred embodiments of the present invention; however, the characteristics of the present invention are by no means restricted thereto. All changes, alternations, or modifications conveniently considered by those skilled in the art are deemed to be encompassed within the scope of the present invention delineated by the following claims.