Abstract:
An AC adapter having a dual-bodied plug that can be rotated by 90 degrees relative to the adapter case so that the plug can be stored in the case when the adapter is not used and drawn out of the case when the adapter is in use. A blade distance adjusting unit provided in the case adjusts the distance between the blades of the plug. When the plug is drawn out of the case, the distance between the blades is increased up to the predetermined value. When the plug is stored in the case, the distance between the blades is reduced. The AC adapter can use a thinner case than conventional AC adapters of which plugs are monolithically structured.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an AC adaptor, and more particularly, to an AC adapter with a rotative plug. 
     2. Description of the Related Art 
     AC adapters are used for various purposes such as the recharging of mobile phones and the converting of AC voltage into a desired AC voltage or a DC voltage. 
     For compactness and mobility, an AC adapter sometimes has a plug that can be stored in the case of the AC adapter by rotating the plug by 90 degrees to the case. 
     By reference to FIGS. 9A and 9B, a description on a conventional AC adapter will be given below. FIG. 9A is the front view of the AC adapter, and FIG. 9B is the cross sectional view of the AC adapter in FIG.  9 A. 
     The AC adapter  1  is provided with a case  2  formed by insulating resin and a plug  3 . The plug  3  consists of blades  4   a  and  4   b  that are made of conductive metal material and a holder  5  that is formed by molding resin material to hold an edge of each of blades  4   a  and  4   b.  A circuit board (not shown) that converts AC voltage into DC voltage is provided in the case  2 . 
     A rotative axis  6  is extruded from the holder  5  of the plug  3 . A bearing unit  7  that supports the rotative axis  6  is provided in the case  2 . The plug  3  can rotate around the rotative axis  6  up to 90 degrees in the rotative direction shown by an arrow in FIG. 9A, between a state where the plug  3  is stored in the case  2  (shown by a dotted line in FIG. 9A) and another state where the plug  3  is extracted from the case  2  (shown by a solid line in FIG. 9A) for connection with an outlet (not shown). The holder unit  5  of the AC plug  3  has contacting units that are connected to the respective blades. On the other hand, the circuit board in the case  2  is provided with contacts made of leaf spring, for example. The contacting units elastically touch the contacts when the plug  3  is rotated. The detailed explanation will be given later. 
     In the AC adapter  1  described above, the blades  4   a  and  4   b  of the plug  3  are provided on opposite sides of the rotative axis  6  in a fashion where the wide faces of the blades face each other. 
     The AC adapter  1  that can store the plug  3  internally is used in a state where the plug  3  is raised after a 90-degree rotation or in a state where the plug  3  is further locked with an interlocking mechanism using a protrusion and a notch (not shown). 
     However, since the plug of a conventional AC adapter has a monolithic structure of blades and a holder, it is necessary to have enough space in the case of the AC adapter to store the plug, which is an obstacle to designing a small case, that is, a small AC adapter. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a general object of the present invention to provide a novel and useful AC adapter in which one or more of the problems described above are eliminated. 
     Another and more specific object of the present invention is to provide an AC adapter in which the size of the case can be reduced by reducing the distance between two blades of the plug when the plug is stored in the case. 
     According to an aspect of the present invention, an AC adapter includes a case, a plug that can be rotated by 90 degrees about one axis relative to said case, so that said plug can be stored in said case and drawn out of said case, and a blade distance adjusting unit, wherein said plug further comprises a pair of sub-holders, each holding a blade, said blade distance adjusting unit causes at least one of said pair of sub-holders to slidingly approach the other to reduce the distance between the blades when said plug is stored in said case, and to slidingly separate from the other to increase said distance between the blades when said plug is drawn out of said case. 
     Accordingly, when the plug is drawn out of the case, the two sub-holders separate from each other so that the distance between the blades increases up to the predetermined value. On the other hand, when the plug is stored in the case, the two sub-holders approach each other, or even contact, so that the distance between the blades is reduced. The AC adapter according to the present invention can use a thinner case than conventional AC adapters of which plugs are monolithically structured. 
     The AC adapter according to the present invention described above is characterized in that said plug has a rotative axis perpendicular to a plane in which said plug is rotated to be drawn out of said case, said case has a bearing unit that supports said rotative axis of said plug, said blade distance adjusting unit comprises a tongue unit formed on one of the sub-holders, said blade distance adjusting unit further comprises a convex stripe unit formed near said bearing unit, said convex stripe unit being substantially “L”-shaped, and said tongue unit is guided by said convex stripe unit when said plug is rotated around said rotative axis so that said distance between the blades is adjusted. 
     In this aspect, a stopper unit of an appropriate structure is provided at a certain position in the case. When the plug is drawn out of the case, one of the sub-holders is stopped by the stopper unit so that the distance between the blades is adjusted to a predetermined value. 
     That the AC adapter described above is further characterized in that said plug has a rotative axis perpendicular to a plane in which said plug is rotated to be drawn out of said case, said case has a bearing unit that supports said rotative axis of said plug, said blade distance adjusting unit comprises a protrusion unit formed on a side face of the sub-holders, said blade distance adjusting unit further comprises a guiding ditch unit formed near said bearing unit, said guiding ditch unit being substantially “L”-shaped, and said protrusion unit is guided by said guiding ditch unit when said plug is rotated around said rotative axis so that said distance between the blades is adjusted. 
     In this aspect, the distance between the rotative axis and the ditch unit is set at a predetermined value so that, when the plug is raised out of the case, the distance between the blades becomes a predetermined value. A stopper having an appropriate structure is provided at a certain position in the case. When the plug is raised out of the case, the stopper stops the sub-holder so that the distance between the blades is set at a predetermined value. 
     The AC adapter according to the present invention described above further includes a circuit board provided in said case, and is characterized in that each of the sub-holders has a stick-shaped contacting unit extruded in parallel to said rotative axis, said contacting unit being electrically connected to the blade held by the sub-holder, a pair of elastic contacts facing each other stand on said circuit board, said contacting unit separates from the contact when said plug is stored in said case and touches the contact when said plug is drawn out of said case. 
     Even in the long run, the elastic contacts damage the contacting units much less than inelastic contacts do and sustain good electric connection. 
     Other objects, features, and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded view of an AC adapter as the first embodiment of the present invention; 
     FIG. 2 is a schematic drawing showing how a plug is attached to the AC adapter showed in FIG. 1; 
     FIG. 3A is a schematic drawing showing the movement of the plug of the AC adapter showed in FIG. 1 where blades are stored in the case; 
     FIG. 3B is a schematic drawing showing the movement of the plug of the AC adapter showed in FIG. 1 where blades are raised out of the case; 
     FIG. 4A is a schematic drawing showing one of the half portions of the holder and the protrusion in a state corresponding to FIG. 3A for further description about the movement of the plug included in the AC adapter showed in FIG. 3A; 
     FIG. 4B is a schematic drawing showing the half portion of the holder showed in FIG. 4A in a state corresponding to FIG. 3B; 
     FIG. 5 is a schematic drawing showing the movement of a contacting unit relative to a contact of the AC adapter showed in FIG. 1; 
     FIG. 6 is an exploded view of an AC adapter as the second embodiment of the present invention; 
     FIG. 7A is a schematic drawing showing the movement of the plug of the AC adapter showed in FIG. 6 where blades are stored in the case; 
     FIG. 7B is a schematic drawing showing the movement of the plug of the AC adapter showed in FIG. 6 where blades are raised out of the case; 
     FIG. 8A is a schematic drawing showing one of the holder half units and the guiding groove in a state corresponding to FIG. 7A; 
     FIG. 8B is a schematic drawing showing one of the holder half units and the guiding groove in a state corresponding to FIG. 7B; 
     FIG. 9A is a side view showing a conventional AC adapter where blades are raised out of the case; and 
     FIG. 9B is a partial sectional view showing the conventional AC adapter where blades are stored in the case. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A detailed description of the preferred embodiments will be given below by reference to the drawings. 
     An AC adapter according to the first embodiment of the present invention will be described by reference to FIGS. 1-5. 
     As showed in FIG. 1, the AC adapter  10  as the first embodiment of the present invention is mainly structured by a plug  16 , a circuit board  18 , and a case  22 . The plug  16  consists of two holder half units  14   a  and  14   b  made of insulating resin, for example, and respective conductive metal blades  12   a  and  12   b  extruded out of the holder half units. The blades constitute a pair. The circuit board  18  converts AC voltage into DC voltage. The case  22  consists of the case upper half unit  20   a  and a case lower half unit  20   b  both made of insulating resin, for example, and stores the plug  16  and the circuit board  18 . A reference numeral  24  indicates a component made of elastic artificial resign, for example, which is used with the plug  16  to create a “click” feeling. 
     The holder half unit  14   a  has a rectangular unit  26  formed step-wise, a plate unit  28  formed at a distance from the rectangular unit  26 , and a tongue unit  30  extruded on a side of the rectangular unit  26  in a circular arc-wise direction. A stick-shaped contacting unit  32  made of conductive metal is provided on a side of the rectangular unit  28 . 
     The holder half unit  14   b  has a circular cylindrical unit  36  on which a concave unit  34  is formed step-wise on a side. A rotative axis  38  extends on a face that is perpendicular to the face on which the concave unit  34  of the circular cylindrical unit  36  is formed. A stick-shaped contacting unit  40  made of conductive metal is provided on the rotative axis  38 . A rotative axis  42  is also provided on the opposite side from which the contacting unit  40  is provided. On the outer diameter of the rotative axis  42 , a plurality of concavities and convexities  42   a  are formed. 
     Two holder half units  14   a  and  14   b  are combined by tightly fitting the rectangular unit  26  and the concave unit  34 , and constitute the plug  16 . As shown in FIG. 2, when the holder half units  14   a  and  14   b  are combined, a circular gap (groove)  72  is formed between the tongue unit  30  and the circular cylindrical unit  36 . The two holder half units  14   a  and  14   b  can be separated in the direction X 1 -X 2  as showed in FIG.  1 . 
     On the circuit board  18 , a pair of contacts  44   a  and  44   b  made of conductive metal and having U-shaped tops stands facing each other. 
     In the case upper half unit  20   a,  a pair of vertical wall unit  46   a  and  48   a  between which the plug  16  is stored is provided facing each other. One side of the space “A” between the vertical wall units  46   a  and  48   a  is connected to an opening “B” formed on a side face. Two semi-circle-shaped bearing half units  50   a  and  52   a  are formed on the wall units  46   a  and  48   a.  The reference marks  54   a  and  56   a  each indicate a circular cylindrical unit having a hole to insert stopping members. 
     The case lower half unit  20   b  substantially corresponds to the case upper half unit  20   a,  and is provided with a pair of vertical wall units  46   b  and  48   b  having respective bearing half units  50   b  and  52   b,  and circular cylindrical units  54   b  and  56   b.  However, in the case lower half unit  20   b,  an opening “E” connected to the space “D” between the wall units is provided on the bottom face as well as on the side face. 
     When the AC adapter  10  is assembled, the bearing half units  50   a  and  50   b,  and the bearing half units  52   a  and  52   b  form bearing units, respectively. 
     A convex stripe unit  62  (showed with hatching in FIG. 1) is formed on a side face of the bearing half unit  50   b.  The convex stripe unit  62  will be described in more detail later. 
     The click feeling creation member  24  consists of a bottom unit  64 , two elastic nail units  66   a  and  66   b,  and a base unit  68  combining the bottom unit  64  and the two elastic nail units  66   a  and  66   b,  and further consists of an L-shaped stopping unit  70  on the opposite side of the base unit  68 . 
     When one assembles the AC adapter  10  including the above components, the circuit board  18  is first fixed to the case lower half unit  20   b.  Then, two holder half units  14   a  and  14   b  are combined by being fitted together tightly. Next, the click feeling creation member  24  is attached to the rotative axis  42 . The outer circle of the rotative axis  42  touches the bottom unit  64 . The nails of the elastic nail unit  66   a  and  66   b  stop the concave portions of the rotative axis  42 . The rotative axis  42  and the rotative axis  38  are positioned on the bearing half unit  52   b  and the bearing half unit  50   b,  respectively, and the stopping unit  70  is tightly fitted to the protrusion unit  60  to attach the plug  16  and the click feeling creation member  24  to the case lower half unit  20   b.  Furthermore, the case lower half unit  20   b  is covered with the case upper half unit  20   a  by carefully positioning corresponding portions between the case upper half unit  20   a  and the case lower half unit  20   b.  Finally, the assembly of the AC adapter  10  is completed by inserting and fixing stopping members (not shown) such as screws through the holes of the circular cylindrical units  54   a,    54   b,    56   a,  and  56   b.    
     A description on the convex stripe unit  62  of the bearing half unit  46   b  is given below by reference to FIG.  2 . As indicated by the reference mark  62   a,  the inner circle of the convex stripe unit  62  is formed circular-arc-wise in parallel to the bearing half unit  50   b.  However, the outer edge of the convex stripe unit  62  is formed by three portions  62   b,    62   c,  and  62   d.  The portion  62   b  is formed circular-arc-wise in parallel to the inner bearing face of the bearing half unit  50   b  between the horizontal direction and the downward direction forming an angle of 90 degrees with the horizontal direction. The portion  62   b  is followed by the horizontal straight portion  62   c,  and further followed by the straight portion  62   d  that forms an obtuse angle with the straight portion  62   c.  The distance between the bearing face and the portion  62   d  is greater than the distance between the bearing face and the portion  62   c,  and the distance between the bearing face and the portion  62   c  is greater than the distance between the bearing face and the portion  62   b.    
     The plug  16  consisting of two combined holder half units  14   a  and  14   b  is positioned downward to the case lower half unit  20   b,  and the gap  72  formed between the tongue unit  30  and the circular cylindrical unit  36  is fitted and related to the convex stripe unit  62 . When the plug  16  is rotated by 90 degrees in the rotative direction as showed in FIG.  2  and positioned along the X 1 -X 2  directions, the plug  16  is stored in the case lower half unit  20   b.    
     Additionally, in the completed AC adapter  10 , when the plug  16  is further rotated downward by 90 degrees, the tongue unit  30  moves along the outer edge of the convex stripe unit as a guide, and the blades  12   a  and  12   b  of the plug  16  are drawn out of the case  22  through the opening E. The detailed explanation will be given later. 
     By reference to FIGS. 3A,  3 B,  4 A, and  4 B, the operation of the plug  16  of the AC adapter  10  will be described below. FIGS. 4A and 4B correspond to FIGS. 3A and 3B, respectively. FIGS. 4A and 4B schematically depict only the relationship between the holder half unit  14   a  holding the blade  12   a  and the convex stripe unit showed in FIGS. 3A and 3B. 
     As showed in FIG. 3A, when the AC adapter  10  is not in use, the plug  16  is stored in the case  22 , which makes the AC adapter  10  handy to carry. When the plug  16  is stored in the case  22 , the tongue unit  30  is related to the boundary portion of the circular arc unit  62   b  and the horizontal straight unit  62   c.  Accordingly, while the plug  16  is stored in the AC adapter  10 , the two holder half units  14   a  and  14   b  are set in a state where the rectangular unit  26  completely enters the concave unit  34  and the two holder half units  14   a  and  14   b  are set most closely together. The thickness H 1  of the case  22  depends on the distance L 1  between the blades  12   a  and  12   b  in this state. 
     As showed in FIG. 3B, when a user uses the AC adapter  10 , the user is required to insert his/her finger through the opening “C” (see FIG. 1) on the side face of the case  22  to catch the blade  12   a,  and draw the blade  12   a  downward through the opening “E” (see FIG. 1) on the bottom face of the case  22 . The blade  12   b  automatically follows the blade  12   a  and is drawn out of the case  22  together with the blade  12   a.  When the blade  12   b  is drawn out of the case  22 , the holder half unit  14   b  rotates around the rotative axes  38  and  42  (see FIG.  1 ). 
     As showed in FIG. 4B, as to the holder half unit  14   a  holding the blade  12   a,  the tongue unit  30 , moving off the bearing unit  50   b  (or the rotative axis), moves horizontally (in the direction indicated by “X” in FIG. 3B and  4 B) along the straight portion  62   c  of the convex stripe unit. Since the rectangular unit  26  recedes from the innermost space in the concave unit  34 , the holder half unit  14   a  and the holder half unit  14   b  separate. Accordingly, the tongue unit  30  and the convex stripe unit  62  operate as a blade distance adjusting unit. 
     As showed in FIG. 3B, when the blade  12   a  is drawn out of the case by rotating the blade  12   a  by 30 degrees downward, for example, the blades  12   a  and  12   b  are distant by L 2 . Even when the blade  12   a  is drawn 90 degrees downward out of the case, the blades  12   a  and  12   b  keep the same distance of L 2 . When the holder half unit  14   a  separating from the holder half unit  14   b  is rotated by 90 degrees, the back face of the tongue unit  30  moves along a stopper unit (not shown) of the case  22 , and the holder half unit  14   a  is fixed at that position. The holder half unit  14   a  does not separate from the holder half unit  14   b  more than the predetermined distance L 2 . 
     The plug  16  is rotated 90 degrees to be stored in the case  22  and drawn out of the case  22 . On the other hand, the blade  12   a  slides to adjust the distance between the blades  12   a  and  12   b.    
     When the blade  12   a  is drawn out of the case and the rotative axis  42  rotates, the concave and convex units  42   a  of the rotative axis  42  touch a pair of elastic nail units  66   a  and  66   b  of the click feeling creation member  24 , which makes a user feel a comfortable clicking feeling. 
     The above distance L 2  is a predetermined distance defined by the industrial standard and required whenever the AC adapter  10  is in use. In the case of the AC adapter as the first embodiment of the present invention, when the AC adapter is not in use, the distance between the blades is reduced so that the plug can be stored in a slim case. On the other hand, when the AC adapter is used, the blades are drawn out of the case with a finger and the distance between the blades becomes the predetermined distance. 
     The electric contacting mechanism between the contacting unit of the blade and the contact of the circuit board used in the AC adapter  10  as the first embodiment of the present invention will be described by reference to FIG.  5 . 
     When the blades  12   a  and  12   b  are stored in the case  22 , the contacting units  32  and  38  stay at a position that is rotated by 90 degrees relative to the contacts  44   a  and  44   b  standing on the circuit board  18  facing one another. When the blade  12   a  is rotated by 30 degrees, for example, and drawn out of the case  22  downward, the contacting units  32  and  38  touch the contacts  44   a  and  44   b,  respectively. When the blade  12   a  is further rotated up to the 90-degree position, the contacting units  32  and  38  touch and press elastically the contacts  44   a  and  44   b.  Accordingly, the electric contacting mechanism surely sustains the electric contact between the plug and the circuit board without a problem such as a wear-out failure where the contacting unit is worn out by repeatedly touching an inelastic contact. 
     A description of an AC adapter according to the second embodiment of the present invention will be given below by reference to FIGS. 6-8. 
     As to the AC adapter as the second embodiment of the present invention, the basic structure is identical to that of the AC adapter  10  shown in FIG.  1 . Accordingly, as to the AC adapter as the second embodiment of the present invention, elements that are identical to those of the AC adapter  10  will be referred to by the same numerals, and their description will be omitted. 
     As to the AC adapter as the second embodiment of the present invention, the structure of the two holder half units and a case and the distance adjusting mechanism are different from those of the AC adapter  10  as the first embodiment of the present invention. The contacting units and the circuit board on which the contacts are provided are not shown in FIGS. 6-8. 
     As shown in FIG. 6, the AC adapter  74  as the second embodiment of the present invention includes a plug  78  consisting of two holder half units  76   a  and  76   b  made of insulating resin, for example, from which a pair of conductive metal blades  12   a  and  12   b  are protruded, respectively, and a case consisting of case upper and lower half units  80   a  and  80   b  made of insulating resin that stores the plug  78  therein. 
     In the holder half units  76   a  and  76   b,  concave units  84  and  86  are formed so that the holder half units  76   a  and  76   b  can be combined by fitting tightly and be separated again. In the holder half unit  76   a,  a rotative axis  42  that is supported by the click feeling creating member  24  is provided, and the bearing half unit  88   a  is also provided on the other side. On the other hand, a rotative axis half unit  88   b  is provided in the holder half unit  76   b  and constitutes a rotative axis  88  when the holder half unit  76   b  is combined with the holder half unit  76   a.  The holder half unit  76   b  has a protrusion unit  90  on the other side opposite to the side where the rotative axis half unit  88   b  is provided. 
     A pair of vertical wall units  92   a  and  94   a  is formed in the case upper half unit  80   a  for the storing of the plug  78 . On vertical wall units  92   a  and  94   a,  semi-circle-shaped bearing half units  96   a  and  98   a  are formed, respectively. An L-shaped ditch unit  100   a  is formed near the bearing half unit  98   a  of the vertical wall unit  94   a.    
     Corresponding to the case upper half unit  80   a,  a pair of vertical wall units  92   b  and  94   b  is formed in the case lower half unit  80   b.  On each vertical wall unit  92   b  and  94   b,  a bearing half unit  96   b  and  98   b  is formed, respectively. A ditch unit  100   b  is formed circular-arc-wise in parallel to the circular face of the bearing half unit  98   b.  The ditch unit  100   b  is connected to the ditch unit  100   a  when the AC adapter  74  is assembled. 
     As shown in FIG. 8, when the AC adapter  74  is assembled, the bearing half units  96   a  and  96   b  form a bearing unit, and the bearing half units  98   a  and  98   b  form another bearing unit. The ditch units  100   a  and  100   b  form an L-shaped ditch unit  100 . 
     The operation of the plug  78  of the AC adapter  74  will be explained by reference to FIGS. 7A,  7 B,  8 A, and  8 B. FIGS. 8A and 8B correspond to FIGS. 7A and 7B, respectively. FIGS. 8A and 8B show only the holder half unit  76   b  supporting the blade  12   b  and the ditch unit  100  formed on the vertical wall unit  94   a  and  94   b  for highlighting the relationship between them. 
     As showed in FIG. 7A, when the AC adapter  74  is not used, the plug  78  is stored in the case  82 . As shown in FIG. 8A, the protrusion unit  90  stays in the guiding ditch  100  at the nearest position to-the rotative axis  42  (or corresponding bearing unit) where two holder half units  76   a  and  76   b  are attached the most closely. Based on the distance L 3  between the blades  12   a  and  12   b,  the thickness H 2  of the case  22  is determined. 
     When the AC adapter  74  is in use, the blades  12   a  and  12   b  are drawn out of the case  22 . The holder half unit  76   a  supporting the blade  12   a  rotates around the rotative axis  88  and  42  (see FIG.  6 ). On the other hand, as shown in FIG. 8B, the holder half unit  76   b  holding the blade  12   b  moves from the position showed in FIG. 8A off the rotative axis  88  and  42  since the protrusion unit  90  is guided by the guiding ditch  100 . The holder half units  76   a  and  76   b  move in different ways and separate from each other. The protrusion unit  90  and the guiding ditch  100  operate as the distance adjustment mechanism. 
     The holder half unit  76   a  moves along a stopper unit (not shown) of the case  82 . The holder half unit  76   a  stops when the blade  12   a  is drawn out of the case  82  by 90 degrees and fixed. The holder half unit  76   a  does not separate from the holder half unit  76   b  more than a predetermined distance. 
     When being drawn out of the case  82 , the distance L 4  between blades  12   a  and  12   b  is a predetermined distance defined as the industrial standard. 
     The AC adapter  74  as the second embodiment of the present invention provides the same effect as the AC adapter  10  as the first embodiment of the present invention. 
     The preferred embodiments of the present invention are described above. The present invention is not limited to these embodiments, but various variations and modifications may be made without departing from the scope of the present invention. 
     This patent application is based on Japanese priority patent application No. 2001-175816 filed on Jun. 11, 2001, the entire contents of which are hereby incorporated by reference.