Patent Publication Number: US-6334791-B1

Title: Load connector

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates to a load connector, and more particularly to a load connector in which a circuit board is disposed in the collar and the inner and outer circumferences of the circuit board are respectively electroplated with two annular conductive layers. A chip resistor or a film resistor is disposed between the two conductive layers to shorten the internal using space of the load connector and achieve an optimal electric appliance property. 
     (2) Description of the Prior Art 
     In television systems such as cable television system (CATV), closed-circuit television system (STV) and common antenna television system (MATV), coaxial cables are used to transmit the signals to wide customers. Referring to FIGS. 1A and 1B, generally, multiple distributors  10  are disposed on the main trunk of these television systems. The distributors  10  via coaxial cables transmit signals to the customers. However, the number of the customers will not be just equal to the number of the output terminals of the distributors. Therefore, a load connector  12  with impedance coupling is used to connect with the not used output terminal  11  to avoid leakage of the signals which will lead to signal interference. In order to eliminate the signal interference, the load connector is mounted on the not used output terminal to avoid impedance discoupling between the coaxial cable for outputting signals and the coaxial cable of the customers. 
     Such load connector  12  includes a main body  13  formed with an inner thread section  14  and a receptacle  15 . The inner thread section  14  is screwed on a not used output terminal  11 . A resistor  16  is positioned in the receptacle  15 . A lead  17  at rear end of the resistor  16  extends out of the main body  13  and fixedly soldered on the main body  13 . A lead  18  at front end of the resistor  16  extends out of the main body  13  to connect with a contact element of the not used output terminal  11  so as to form impedance coupling. 
     The requirement for receiving frequency has been higher and higher nowadays. The frequency has been increased from 550 MHz to 1000 MHz or higher. Therefore, the commercially available load connector must be applicable to high frequency. However, the resistor  16  mounted in the conventional load connector  12  is the widely used 75 Ω resistor which has considerably large volume. Therefore, the total length of the load connector  12  is increased relatively. In the case of burglarproof load connector or double-head (male-female head) load connector, the total length thereof will be even longer. The longer the total length of the load connector is, the smaller the back loss of the electric appliance achieved at high frequency is. Such back loss can hardly meet the requirement of U.S. electric appliance specification standard (SCTE) that the back loss should be over 30 dB. Therefore, the excessively long load connector will directly affect the video quality and can hardly meet the requirement of high frequency. 
     Therefore, it is necessary to provide a load connector which can achieve larger back loss of electric appliance and meet the requirement of high frequency. 
     SUMMARY OF THE INVENTION 
     It is therefore a primary object of the present invention to provide a load connector in which a circuit board is disposed in the collar. The inner and outer circumferences of the circuit board are respectively electroplated with two annular conductive layers. A chip resistor or a film resistor is disposed between the two conductive layers to greatly shorten the internal using space of the load connector and achieve a good impedance coupling. Accordingly, the total length of the load connector is shortened to achieve an optimal electric appliance property when connected with the distributor. 
     It is a further object of the present invention to provide the above load connector in which an O-ring is disposed on outer side of the wall of the flange end section of the collar, whereby when the load connector is connected with the output terminal of the distributor, the O-ring is compressed between the output terminal and the collar to achieve a moisture-tight seal. 
     The present invention can be best understood through the following description and accompanying drawings wherein: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a perspective exploded view of a conventional distributor and load connector; 
     FIG. 1B is a sectional view of a conventional load connector; 
     FIG. 2 is a sectional view of the load connector of the present invention; 
     FIG. 3 is a perspective exploded view of the load connector of the present invention; 
     FIG. 4 is a sectional view of the main body of the load connector of the present invention; 
     FIG. 5 is a sectional view of the collar of the load connector of the present invention; 
     FIG. 6A is a plane view of a first embodiment of the circuit board of the present invention; and 
     FIG. 6B is a plane view of a second embodiment of the circuit board of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Please refer to FIGS. 2 and 3. The load connector  20  of the present invention includes a main body  21 , a collar  30  coaxially disposed in the main body  21  and a circuit board  40  coaxially disposed in the collar  30 . Referring to FIG. 4, the main body  21  is formed with a first tubular end section  22 , a second tubular end section  23 , a hexagonal body section  24  and a lateral end section  25 . The first tubular end section  22  is formed with an inner thread  26  and two annular sections  27 ,  28 . The inner thread  26  is able to connect with an output terminal of a distributor and ends at an annular section  26 . 
     Referring to FIG. 5, the collar  30  has a flange end section  31  and an interface section  32 . The interface section  32  defines an annular groove  33  which is such dimensioned as to receive the circuit board  40  therein. The interface section  32  ends at an inner shoulder section  34 . The flange end section  31  defines a perforation  35 . A sealing member such as an O-ring  36  is disposed on outer side of the wall of the flange end section  31 . 
     Referring to FIG. 6A, the circuit board  40  is positioned in the annular groove  33  and fixedly soldered in the collar  30 . The circuit board  40  is formed with a through hole  41  which is such dimensioned as to receive therein a central pin  43 . The outer circumferences of the through hole  41  and the circuit board  40  are respectively electroplated with two annular conductive layers  42 . At least one chip resistor  44  or a donut-shaped film resistor  45  (as shown in FIG. 6B) is disposed between the two conductive layers  42 . When the central pin  43  is inserted into a contact element in the output terminal, an impedance coupling is formed. 
     When the inner thread  26  of the load connector  20  is connected with the output terminal of the distributor, the O-ring is compressed between the output terminal and the collar  30  to form a moisture-tight seal for preventing moisture from entering the connector  20  to interfere with the video quality. 
     In the load connector  20  of the present invention, the chip resistor  44  or film resistor  45  is associated with the circuit board  40  so as to greatly shorten the internal using space and thus change the total length of the load connector  20 . Accordingly, the back loss of electric appliance is over 30 dB and an optimal electric appliance property can be achieved to meet U.S. electric appliance specification standard. 
     The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without departing from the spirit of the present invention.