Patent Publication Number: US-6658233-B1

Title: Satellite broadcast receiving converter

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to satellite broadcast receiving converters, and more specifically to a satellite broadcast receiving converter which is used to receive satellite broadcasts and satellite communications, and which receives circularly polarized waves having a vertical polarization component and a horizontal polarization component. 
     2. Description of the Related Art 
     Referring to FIGS. 10 to  13 , there is shown a conventional satellite broadcast receiving converter. FIG. 10 is a perspective view of the converter, and FIG. 11 is a sectional view thereof taken along such a line XI—XI of FIG.  10 . FIG. 12 is a partially enlarged view of the converter, showing how a probe is installed. FIG. 13 is a partially enlarged view of the converter, showing a circuit board mounted therein. 
     A housing  31  and a waveguide  32  are manufactured by die-casting with a metal such as aluminum or zinc and then forming the components into one unit. The housing  31  is formed into a substantially rectangular box, including a bottom wall  31   a,  side walls  31   b  that are vertical and which surround the bottom wall  31   a,  a housing portion  31   c  that is uncovered and is defined by the side walls  31   b,  a penetrating hole  31   d  formed in the bottom wall  31   a  in the vicinity of one end thereof and extending perpendicularly thereto, and a stepped portion  31   e  having a step along an upper periphery of the side walls  31   b.  The waveguide  32  is a relatively narrow cylinder, extending from the bottom wall  31   a  at a position corresponding to the penetrating hole  31   d.  The waveguide  32  includes a substantially cylindrical tube section  32   b  having an opening  32   a  from which polarized waves are guided, a hollow  32   c  formed lengthwise at the center of the tube section  32   b,  and a holder portion  32   d.  The holder portion  32   d  is a semi-columnar recess, as shown in FIG. 12, which is formed in the tube section  32   b  to extend toward the opening  32   a  from a portion of the periphery of the penetrating hole  31   d  of the housing  31 . 
     A probe  33  for detecting horizontally polarized waves is composed of a tubular insulator  33   a  made of resin such as fluorine resin, polyethylene, or Teflon, and a linear core conductor  33   b  passing through the insulator  33   a  at the center thereof and mainly made of a metal such as brass or nickel. The core conductor  33   b  is formed into substantially an L-shape, leading to a first end  33   c  while the other end thereof, namely a second end  33   d,  is formed at the tip of the straight part. 
     Referring to FIG. 12, the insulator  33   a  is forced into the holder portion  32   d  in the waveguide  32 , allowing the probe  33  to be installed into the waveguide  32 . Once the probe  33  has been installed, the second end  33   d  of the core conductor  33   b  protrudes into the housing portion  31   c  of the housing  31  while the first end  33   c  extends into the hollow  32   c  of the waveguide  32 . 
     In FIG. 13, there is shown a rectangular circuit board  34  formed of a single insulating sheet. The circuit board  34  includes a thin flat plate  34   a,  three penetrating holes  34   b  formed in the vicinity of a side edge of the plate  34   a  and extending perpendicularly thereto, bridges  34   d  and  34   e  defining the penetrating holes  34   b  to form a T-shape, and a small opening  34   c  formed in the vicinity of the penetrating holes  34   b.  A copper ground conductor  35  is formed on the underside of the circuit board  34  except for the underside of the bridge  34   e,  and the underside of the bridge  34   d  serves as a short-circuit for the probe  33 . 
     A probe  36  for detecting vertically polarized waves is formed across the bridge  34   e  with a conductive pattern, and extends from the intersection of the bridges  34   d  and  34   e  toward the plate  34   a  of the circuit board  34 . In turn, the probe  36  is connected to a circuit pattern (not shown) formed on the top of the plate  34   a.  The circuit board  34  is contained on the bottom wall  31   a  of the housing  31  so that the penetrating hole  31   d  may communicate with the penetrating holes  34   b  in the plate  34   a.  Also, the second end  33   d  of the core conductor  33   b  of the probe  33  is inserted in the opening  34   c  in the plate  34   a,  and the circuit board  34  is then fixed to the bottom wall  31   a  of the housing  31  by any appropriate means. The second end  33   d  of the core conductor  33   b  that protrudes from the circuit board  34  is soldered by a solder  37  to the circuit pattern. 
     A box-shaped metallic short-circuit wall  38  is formed by aluminum or zinc die-casting. The short-circuit wall  38  is mounted to the circuit board  34  by an appropriate technique such as caulking so as to cover the penetrating holes  34   b  in the circuit board  34 . The short-circuit wall  38  has a base  38   a  acting as a short-circuit for the probe  36 . 
     A cover  39  formed of a single rectangular metal sheet is placed on the step  31   e  of the side walls  31   b  of the housing  31 , and is fixed thereto by an appropriate technique. Accordingly, the housing portion  31   c  of the housing  31  is closed and electrically shielded. 
     Such a conventional satellite broadcast receiving converter is of the type in which the housing  31  and the waveguide  32  are manufactured by die-casting such as aluminum die-casting and then forming the components into one unit. Therefore, a large number of materials are required, resulting in increased material costs as well as prolonged manufacturing time. This makes the converter expensive and less efficient in production. 
     In addition, the following problem also occurs with such a conventional satellite broadcast receiving converter. The housing  31  and the waveguide  32  have different sizes and configurations, and therefore more complex and expensive die-casting molds are required. This also makes the converter more expensive. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a satellite broadcast receiving converter which has superior production efficiency and is inexpensive. 
     To this end, a satellite broadcast receiving converter according to the present invention has a metal housing formed into a box, a tubular waveguide, and a box-shaped short-circuit wall which opposes the waveguide so as to communicate with a hollow formed in the waveguide, wherein the housing, the waveguide, and the short-circuit wall are joined together on a single metal sheet. These components are stamped out of the metal sheet, and then folded. With this feature, the number of materials making up the converter can be reduced. A simple manufacturing process as well as shortened manufacturing time can also be obtained. 
     The converter may include a circuit board on which an electric circuit is formed, wherein the circuit board is held by and between the housing and an end of the waveguide. This enables the circuit board to be held therebetween in a simple manner. 
     Preferably, the waveguide includes a hooking tab at a free-end edge of the end thereof, which is engaged with the circuit board. The use of a hooking tab ensures that the waveguide is mounted and positioned to the circuit board in a simple manner. 
     Preferably, a folding guide line is formed in a joining portion joining the housing with the waveguide, and the folding guide line may include cuts. The folding guide line facilitates folding of the waveguide at a predetermined position, so that the circuit board can be easily mounted to the waveguide. 
     Accordingly, the present invention provides for a satellite broadcast receiving converter with a simple configuration having high production efficiency as well as high reliability. There is no need for an expensive die-casting mold, so that an inexpensive satellite broadcast receiving converter can be obtained. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an enlarged perspective view of a satellite broadcast receiving converter in accordance with the present invention; 
     FIG. 2 is an enlarged sectional view of the satellite broadcast receiving converter of FIG. 1; 
     FIG. 3 is a perspective view of the satellite broadcast receiving converter, showing that a waveguide and a circuit board are connected to each other; 
     FIG. 4 is a developed view of a semi-finished product member, for illustrating the assembly of the satellite broadcast receiving converter; 
     FIG. 5 is an enlarged view of the circuit board employed in the satellite broadcast receiving converter; 
     FIG. 6 is a perspective view of the satellite broadcast receiving converter, showing that a probe is installed; 
     FIG. 7 is a perspective view of the satellite broadcast receiving converter, showing that the probe is installed; 
     FIG. 8 is a perspective view showing a modification of a holder portion in the satellite broadcast receiving converter; 
     FIG. 9 is a top plan view showing another modification of a holder portion in the satellite broadcast receiving converter; 
     FIG. 10 is a perspective view of a conventional satellite broadcast receiving converter; 
     FIG. 11 is a sectional view of the converter, taken along the line XI—XI of FIG. 10; 
     FIG. 12 is a partially enlarged view of the conventional satellite broadcast receiving converter, showing how a probe is installed; and 
     FIG. 13 is a partially enlarged view of the conventional satellite broadcast receiving converter, showing a mounted circuit board. 
    
    
     DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
     A satellite broadcast receiving converter in accordance with the present invention is now described with reference to FIGS. 1 to  9 . 
     FIG. 1 is an enlarged perspective view of a satellite broadcast receiving converter in accordance with the present invention, and FIG. 2 is an enlarged sectional view of the converter. FIG. 3 is an illustration of the converter, showing that a waveguide and a circuit board are connected to each other. FIG. 4 is a developed view of a semi-finished product member, for illustrating the assembly of the converter. FIG. 5 is an enlarged view of the circuit board in the converter. FIGS. 6 and 7 both illustrate that a probe is installed into the converter. FIG. 8 is a perspective view showing a modification of a holder portion in the converter. FIG. 9 is a top plan view showing another modification of a holder portion in the converter. 
     Throughout these figures, according to the satellite broadcast receiving converter of the present invention, a housing  1 , a waveguide  2  and a short-circuit wall  7  are joined together on a single thin metal sheet. These components are stamped out of the metal sheet and folded. 
     The housing  1  is formed into a box and is made of a thin metal sheet. The housing  1  has a rectangular recess  1   g  formed at the center thereof and a rectangular U-shaped top wall  1   e  that forms an edge of the periphery thereof. At the four sides of the top wall  1   e,  folded down side walls  1   a,    1   b,    1   c,  and  1   d  are provided so as to be upright. Each of the side walls  1   a,    1   b,    1   c  and  1   d  is joined with the top wall  1   e.  An upper portion of the side wall  1   d  that opposes the side wall  1   c  is formed with a large cut-out indented portion  1   h,  which extends across the width of the recess  1   g.  As shown in FIG. 4, a plurality of substantially V-shaped hooking tabs  1   f  are formed at an edge of each of the side walls  1   a,    1   b  and  1   c.    
     The waveguide  2  is made of a thin metal sheet of a rectangular tube, including side panels  2   a,    2   b,    2   c,  and  2   d,  and a hollow  2   e.  The side panel  2   a  extends down from a joining portion  1   i  and the side wall  1   d  of the housing  1 . The side panels  2   b  and  2   d  are angled at 90° relative to the side panel  2   a . The side panel  2   c  is angled at 90° relative to the side panel  2   b,  and is joined with the side panel  2   d  so as to face the side panel  2   a.  The hollow  2   e  is defined by the side panels  2   a,    2   b,    2   c  and  2   d.  The side panels  2   b,    2   c  and  2   d  provide ends  2   f  (see FIG. 6) that lie on free-end edges opposite to the joining portion  1   i.  As shown in FIGS. 2 and 3, two substantially V-shaped hooking tabs  2   g  are formed on the end  2   f  of the side panel  2   c  opposing the side panel  2   a  joined with the housing  1 . In FIG. 4, a substantially rectangular engagement hole  3  is formed in the boundary between the side panels  2   a  and  2   d,  and an insertion hole  4  composed of a round hole portion  4   a  and a square hole portion  4   b  is formed in the side panel  2   d  in the vicinity of the engagement hole  3 . The joining portion  1   i  for joining the side panel  2   a  with the side wall  1   d  of the housing  1  includes a folding guide line  5  having cuts. The waveguide  2  extends perpendicularly to the housing  1  when it is folded and assembled, as shown in FIG.  1 . The waveguide  2  can be tilted on the folding guide line  5  relative to the housing  1 , as indicated by the dotted lines in FIG.  2 . 
     Referring to FIGS. 3 and 4, a holder portion  6  adjoins the side panel  2   c  by a joining portion  2   h  so as to be outside the waveguide  2 . The holder portion  6  includes a body  6   a  of a flat sheet, a curved enclosing section  6   b  formed at the center of the body  6   a,  and a substantially V-shaped hooking tab  6   c  folded at an end of the holder portion  6 , which lies on a free-end edge. 
     The holder portion  6  can be folded down relative to the side panel  2   c  so that the hooking tab  6   c  can be engaged with the engagement hole  3  when the holder portion  6  is folded down to the side panel  2   d.    
     A short-circuit wall  7  is made of a thin metal sheet of a box-shape, including a lid  7   a,  side portions  7   b,    7   c,  and  7   d,  and a cavity  7   e.  The lid  7   a  adjoins the side wall  1   d  of the housing  1 , and is folded 90° relative to the side wall  1   d.  The side portions  7   b,    7   c,  and  7   d  are folded down relative to the lid  7   a.  The cavity  7   e  is defined by the lid  7   a,  the side portions  7   b,    7   c,  and  7   d,  and the side wall  1   d.    
     The short-circuit wall  7  is located in the housing  1  with the cavity  7   e  communicating with the hollow  2   e  of the waveguide  2 . 
     Shown in FIG. 6 is a probe  8  for detecting horizontally polarized waves, including an L-shaped tubular insulator  8   a  made of resin such as fluorine resin, polyethylene, or Teflon, and a linear core conductor  8   b  passing through the center of the insulator  8   a  and mainly made of a metal such as brass or nickel. The core conductor  8   b  is bent substantially at a right angle together with the insulator  8   a,  leading to a first end  8   c  while the other end thereof, namely a second end  8   d,  is positioned substantially at a right angle relative to the first end  8   c.    
     Referring to FIGS. 3 and 7 in particular, the arrangement of the probe  8  is such that one end of the L-shaped insulator  8   a  is fitted into the round hole  4   a  of the insertion hole  4  formed in the side panel  2   d  of the waveguide  2  while the other end of the insulator  8   a  appearing from the waveguide  2  is held between an outer surface of the side panel  2   d  of the waveguide  2  and the enclosing section  6   b  of the holder portion  6 . The enclosing section  6   b  of the holder portion  6  encloses the portion of the insulator  8   a  which appears from the waveguide  2  to hold the insulator  8   a  so that the portion of the core conductor  8   b  which appears from the waveguide  2  can be enclosed by the enclosing section  6   b.    
     When the probe  8  is installed, the second end  8   d  of the core conductor  8   b  projects into the housing  1  while the first end  8   c  extends into the hollow  2   e  of the waveguide  2 . 
     In FIG. 5, there is shown a rectangular circuit board  9  made of a single insulating sheet, including a thin flat plate  9   a,  an indented portion  9   b  formed at one side of the plate  9   a,  three substantially rectangular penetrating holes  9   c  formed in the vicinity of the indented portion  9   b  and extending perpendicularly thereto, bridges  9   g  and  9   h  defining the penetrating holes  9   c  to form a T-shape, a small opening  9   d  formed in the vicinity of the penetrating holes  9   c,  two first engagement holes  9   e  formed in the vicinity of the penetrating holes  9   c  at the position opposite to the indented portion  9   b,  and a plurality of second engagement holes  9   f  formed at the peripheral edge of the circuit board  9 . A copper ground conductor  10  is formed on the underside of the plate  9   a  except for the underside of the bridge  9   h.    
     A probe  11  for detecting vertically polarized waves is formed across the bridge  9   h  with a conductive pattern so as to extend from the intersection of the bridges  9   g  and  9   h  toward the plate  9   a  of the circuit board  9 . The probe  11  is connected to a wiring pattern (not shown) formed on the top of the plate  9   a.  A strip-type copper ground pattern  12  encloses the penetrating holes  9   c  in the flat plate  9   a  so as to be connected with the ground conductor  10  via a plurality of through-holes  12   a  formed in the circuit board  9 . 
     When the circuit board  9  is held between the housing  1  and the waveguide  2 , the top surface of the flat plate  9   a  is brought into contact with the bottom ends of the side walls  1   a,    1   b,    1   c,  and  1   d  of the housing  1  while the undersurface of the flat plate  9   a  is brought into contact with and supported by the ends  2   f  of the waveguide  2 . The hooking tabs  2   g  of the waveguide  2  are engaged with the first engagement holes  9   e,  and the hooking tabs  1   f  of the housing  1  are engaged with the second engagement holes  9   f,  whereby the circuit board  9  can be held between the housing  1  and the waveguide  2 . 
     Also, the top surface of the flat plate  9   a  of the circuit board  9  is brought into contact with the bottom ends of the side portions  7   b,    7   c,  and  7   d  of the short-circuit wall  7 , and the side panel  2   a  of the waveguide  2  is engaged with the indented portion  9   b  of the flat plate  9   a.    
     As shown in FIG. 3., the penetrating holes  9   c  in the circuit board  9  communicates with both the hollow  2   e  of the waveguide  2  and the cavity  7   e  of the short-circuit wall  7 , and the side portions  7   b,    7   c,  and  7   d  of the short-circuit wall  7  are in contact with the ground pattern  12 . The second end  8   d  of the core conductor  8   b  of the probe  8  is inserted through the opening  9   d  in the flat plate  9   a.  The second end  8   d  of the core conductor  8   b  that projects from the circuit board  9  is soldered by a solder  13 , and is connected to a wiring pattern formed on the circuit board  9 . 
     That is, the penetrating holes  9   c  in the circuit board  9  are located within the waveguide  2  as well as within the short-circuit wall  7 , and the underside of the circuit board  9  except for the underside of the bridge  9   h  is shielded with the ground conductor  10 . 
     An L-shaped cover  14 , which is formed of a single rectangular metal sheet, is seated so as to match the side wall  1   d  and the top wall  1   e  of the housing  1 , and is then fixed by an appropriate technique. This allows the housing  1  to be closed and electrically shielded. 
     Now, an assembling process of the thuly arranged satellite broadcast receiving converter according to the present invention is described. FIG. 4 illustrates a semi-finished product member  15  composed of the housing  1 , the waveguide  2  and the short-circuit wall  7 . In the housing  1 , the top wall  1   e  includes the recess  1   g  and the indented portion  1   h  at the center thereof, and the side walls  1   a,    1   b,    1   c,  and  1   d  extend from the four sides of the top wall  1   e.  In the waveguide  2  which is designed to be outside the housing  1 , the side panel  2   a  is continuous with the side wall  1   d.  The side panels  2   b  and  2   c  continuously extend from one side of the side panel  2   a,  and the side panel  2   d  is continuous with the other side of the side panel  2   a.  The holder portion  6  is further continuous with the side panel  2   c  via the joining portion  2   h.  In the short-circuit wall  7  stretching into the recess  1   g  over the indented portion  1   h  in the housing  1 , the lid  7   a  is opposite to the side panel  2   a  via the side wall  1   d,  and the side portions  7   b,    7   c,  and  7   d  extend outward from the lid  7   a.  The housing  1 , the waveguide  2  and the short-circuit wall  7  are stamped out of a thin metal sheet to develop the semi-finished product member  15 . 
     In assembly, the side walls  1   a,    1   b,    1   c,  and  1   d  are folded by 90° at dotted lines A, to form the housing  1 . The side panels  2   b,    2   c,  and  2   d  are folded by 90° at dotted lines B and the side panels  2   c  and  2   d  are then connected to each other, forming the waveguide  2 . The lid  7   a  is folded by 90° at a dotted line C and the side portions  7   b,    7   c,  and  7   d  are folded by 90° at dotted lines D, forming the short-circuit wall  7 . The configuration illustrated in FIG. 1 is thus obtained. 
     The installation of the circuit board  9  will now be described with reference to FIGS. 2 and 3. In FIG. 2, the waveguide  2  extending perpendicularly to the housing  1  is tilted on a folding guide line  5  outward relative to the housing  1  as indicated by the dotted lines of FIG. 2 before positioning the circuit board  9 . Then, the waveguide  2  is returned to the expected position to engage with the circuit board  9 . In order to achieve this operation, first, the hooking tabs  1   f  of the housing  1  are engaged with the second engagement holes  9   f  in the circuit board  9  and the circuit board  9  is disposed beneath the housing  1 . Then, in the waveguide  2 , the hooking tabs  2   g  on the end  2   f,  which lies on a free-end edge opposing to the side panel  2   a  continuous with the joining portion  1   i,  are engaged with the first engagement holes  9   e  in the circuit board  9  as shown in FIG.  3 . This ensures that the circuit board  9  is held between the housing  1  and the waveguide  2 . 
     The installation of the probe  8  into the insertion hole  4  will now be described with reference to FIG.  6 . The probe  8  is turned in the direction indicated by the arrow of FIG. 6 to guide the first end  8   c  of the core conductor  8   b  into the hollow  2   e,  followed by catching the insulator  8   a  against the round hole  4   a,  as shown in FIG.  7 . Then, the holder portion  6  is folded down at the joining portion  2   h,  and the hooking tab  6   c  on the end of the holder portion  6 , which lies on a free-end edge, is engaged with the engagement hole  3  so that the insulator  8   a  is held between the enclosing section  6   b  and the side panel  2   d  to hold the probe  8 . 
     The satellite broadcast receiving converter according to the present invention has been described in conjunction with the arrangement and assembly thereof. In operation, two types of polarized waves orthogonal to each other are guided from the waveguide  2  into the hollow  2   e.  The horizontally polarized waves are reflected by a portion of the ground conductor  10  which is laid over the underside of the bridge  9   g,  and are then detected by the first end  8   c  of the probe  8  extending into the hollow  2   e.  The vertically polarized waves are reflected off of the lid  7   a  of the short-circuit wall  7 , and are then detected by the probe  11  formed over the bridge  9   h.  The horizontally polarized waves detected by the probe  8  are transmitted as horizontally polarized signals to an electric circuit contained on the circuit board  9  via the core conductor  8   b.  The vertically polarized waves detected by the probe  11  are transmitted as vertically polarized signals to the electric circuit on the circuit board  9 . The horizontally and vertically polarized signals transmitted from the probes  8  and  11 , respectively, are combined on the circuit board  9 . 
     It is to be understood that the foregoing embodiment is only illustrative and the satellite broadcast receiving converter according to the present invention is not to be limited to the foregoing embodiment. Various changes and modifications may be contemplated without departing from the spirit and scope of the invention. For example, modifications of the holder portion  6  are illustrated in FIGS. 8 and 9. The holder portion  6  may not have a hooking tab, as shown in FIG. 8, and may hold the insulator  8   a  in such a manner that the holder portion  6  is left folded down at the joining portion  2   h.  The holder portion  6  shown in FIG. 9 encloses substantially the entire circumference of the insulator  8   a  and holds it. 
     It is also to be understood that the folding guide line  5  is not to be limited to one having cuts, as in the foregoing embodiment, but may be one having perforations or the like.