Abstract:
A security device for securing a jack plug during retail display of a product, such as a pair of headphones, that is fitted with a jack plug. The security device comprises a jack plug socket for engagement with the jack plug of the product and operable to lock the jack plug so as to prevent withdrawal of the jack plug from the jack plug socket. In addition, the security device has an input for receiving electrical signals from a source, such as an MP3 player or a mobile phone. The input is electrically connected to the jack plug socket so that electrical signals received at the input are transmitted to the jack plug socket. In addition, the security device is provided with an attachment for attaching the security device to a fixture such as a retail display.

Description:
BACKGROUND 
       [0001]    The invention relates to a security device for securing a jack plug during retail display of a product fitted with a jack plug. 
         [0002]    One type of retail product that is fitted with a jack plug is a pair of headphones. During retail display of a pair of headphones, it is desirable to allow a potential customer to listen to music through the headphones so that the customer can assess the sound quality. The customer may wish, for example, to plug the headphones into his or her MP3 player or mobile phone so that the customer can listen, through the headphones, to music with which the customer is familiar 
         [0003]    When allowing customers to try out headphones as described above, it is also desirable to secure the headphones to a fixture, such as a display stand, so that the headphones cannot be stolen. 
       SUMMARY 
       [0004]    In accordance with a first aspect of the invention, there is provided a security device for securing a jack plug during retail display of a product fitted with a jack plug, the security device comprising: a jack plug socket for engagement with a jack plug and operable to lock a jack plug in said engagement so as to resist withdrawal of the jack plug, an input for receiving electrical signals, the input being electrically connected to the jack plug socket so that electrical signals received at the input are transmitted to the jack plug socket for transmission of the electrical signals from the jack plug socket to a jack plug locked in engagement with the jack plug socket and for onward transmission of the electrical signals to a product connected to the jack plug, and an attachment for attaching the security device to a fixture. 
         [0005]    Accordingly, the security device of the current invention allows a retail product to be secured by securing the jack plug connected to the product. It will be appreciated that the security device can be used with other retail products fitted with a jack plug. The use is not limited to pairs of headphones. 
         [0006]    The term “jack plug” is used to signify an electrical male plug having a single, generally cylindrical pin provided with a plurality of contact areas along its length and the term “jack plug socket” is used to refer to the corresponding female socket. Jack plugs are also commonly known as audio jacks or phone jacks. The term jack plug includes all sizes (e.g. with 2.5 mm, 3.5 mm and 6.35 mm diameter pins). The term jack plug also covers plugs with any plural number of contacts. For example, an audio stereo jack plug commonly has three contacts and is often referred to as a TRS plug (the initials TRS referring to the three contact areas of the pin known as Tip, Ring and Sleeve). An audio mono jack plug commonly has two contacts and is often referred to as a TS (Tip, Sleeve) plug. A four contact plug is commonly referred to as a TRRS (Tip, Ring, Ring, Sleeve) plug. Jack plugs having greater numbers of contacts are available. All such plugs are included within the term “jack plug” and the corresponding jack plug sockets are included within the term “jack plug socket”. The terms “jack plug” and “jack plug socket” are not limited to audio plugs and sockets and also cover all other uses, such as a microphone plug having a cylindrical configuration and the corresponding socket. In general, the tip of a jack plug is separated from ring and sleeve contacts on the jack plug by a neck. The tip generally includes a convex frusto-conical surface which faces generally radially outwardly and rearwardly (ie towards a handle portion of the jack plug). 
         [0007]    Preferably, the security device includes a housing. The jack plug socket is provided in the housing and the attachment allows attachment of the housing to a fixture. In this way, the housing protects and hides the locking mechanism of the jack plug socket. 
         [0008]    Preferably, the jack plug socket comprises a locking member which is moveable between a locking position and a release position. When the locking member is in the release position, the jack plug can be withdrawn from the jack plug socket. The locking member is lockable in the locking position to lock the jack plug within the jack plug socket. When the locking member is in the locking position, the locking member engages a tip of a jack plug. In this case, the shape of the tip of the jack plug allows the locking member to achieve purchase on the jack plug. In this way, locking of the jack plug within the jack plug socket can generally be achieved without deforming the pin of the jack plug. 
         [0009]    Where the jack plug socket has a locking member as described above, the locking member preferably has a concave frusto-conical surface. In this case, the security device is used with a jack plug having a tip which has a convex frusto-conical surface. By providing the locking member with a concave frusto-conical surface which corresponds closely in shape to the convex frusto-conical surface of the tip of the pin of a jack plug, it has been found possible to achieve secure locking of a jack plug within a jack plug socket. 
         [0010]    Where a locking member is provided, the jack plug socket preferably also comprises a rotatable control member which interacts with the locking member. The rotatable control member is rotatable between a first stop at which the locking member is locked in the locking position and a second stop at which the locking member is in the release position. The provision of the two distinct stops is advantageous compared to, for example, a locking screw which can be tightened or loosened without any distinct stops to limit its rotation. The provision of these stops avoids over tightening. 
         [0011]    Where the jack plug socket comprises both a locking member and a rotatable control member, as described above, the locking member preferably has a first end and a second end. The first end is pivoted and the second end of the locking member interacts with the rotatable control member to control movement of the locking member between the locking position and the release position. Where a concave frusto-conical surface is provided on the locking member, this is preferably intermediate the first and second ends of the locking member. In this way, a high degree of positional accuracy of the frusto-conical surface may be achieved. 
         [0012]    When the jack plug socket is provided with a rotatable control member, the security device preferably also includes a security key. The rotatable control member has a formation which is shaped for engagement with the security key so that the rotatable control member can be rotated by the security key between the first and second stops. Even more preferably, the shape of the formation on the rotatable control member is such that it cannot be engaged by a screwdriver with a slot head or a cross-head. In this way, even if a potential customer is able to gain access to the jack plug socket, the customer may not be able to release the jack plug without a security key which corresponds to the formation on the rotatable control member. 
         [0013]    The input of the security device may be any suitable input. It could, for example, be a standard jack plug socket without a locking function. It could also be, for example, a standard USB socket. In one specific embodiment, the input is itself a jack plug which a potential customer can plug into his or her MP3 player or mobile phone. 
         [0014]    In accordance with a second aspect of the invention, there is provided a method of securing a jack plug during retail display of a product fitted with a jack plug, comprising providing a product fitted with a jack plug, providing a security device, securing the security device to a fixture, locking the jack plug in engagement with the security device, and providing an input. The input being electrically connected to the jack plug so that electrical signals received at the input are transmitted to the jack plug for onward transmission of the electrical signals to the product. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The following is a more detailed description of embodiments of the invention, by way of example, reference being made to the following schematic drawings in which: 
           [0016]      FIG. 1  is an isometric view of a security device from which an external lid and an intermediate lid have been omitted in order to show the internal components; 
           [0017]      FIG. 2  is a plan view from above of the security device of  FIG. 1 ; 
           [0018]      FIG. 3  is a cross-sectional view of the security device of  FIGS. 1 and 2 ; 
           [0019]      FIGS. 4 to 8  are isometric views showing components of a jack plug socket of the security device of  FIGS. 1 to 3 ; 
           [0020]      FIG. 9  is a plan view from above of the security device of  FIGS. 1 to 8  showing an intermediate cover in place in the security device; 
           [0021]      FIG. 10  is a plan view from above of the security device of  FIGS. 1 to 9  showing an outer cover in place on the security device. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Looking first at  FIGS. 1 ,  2 ,  9  and  10 , the security device includes a casing bottom  10 , an intermediate lid  12 , an outer lid  14 , a locking jack plug socket generally shown at  16 , and an input in the form of a standard jack plug socket  18 . 
         [0023]    As best seen in  FIG. 1 , the casing bottom  10  is provided with two upstanding attachment bosses  20 . Each attachment boss  20  has a central hole which passes through the casing bottom  10 . In this way, the attachment bosses  20  can be used to attach the casing bottom  10  to a fixture, such as a wooden display stand, by passing two screws through the attachment bosses  20  into the underlying wooden fixture. In addition, the casing bottom  10  is provided with two upstanding support bosses  22 . Each support boss  22  is provided with a blind threaded hole which, as seen best in  FIG. 9 , receives a threaded bolt so as to attach the intermediate lid  12  to the casing bottom  10 . The casing bottom  10  also has an L-shaped rebate  24  which extends around the casing bottom  10  and which receives the outer lid  14  as described below in more detail. 
         [0024]    As best seen in  FIGS. 1 and 3 , the casing bottom  10  also has a first aperture  26  which receives the pin of a jack plug to be engaged in the locking jack plug socket  16  and a second aperture  28  which receives the pin of a jack plug to be engaged in the standard jack plug socket  18 . The standard jack plug socket  18  is omitted from  FIG. 3  for the purposes of clarity. 
         [0025]    Looking now at  FIGS. 1 and 3 , a connection plate  30  is provided near to but spaced from a bottom wall of the casing bottom  10 . The locking jack plug socket  16  and the standard jack plug socket  18  are both mounted on the connection plate  30 . Electrical connections (not shown) are provided on the underside of the connection plate  30  to connect the locking jack plug socket  16  with the standard jack plug socket  18 . In this way, electrical input signals provided to the standard jack plug socket  18  by a jack plug inserted in the standard jack plug socket  18  are transmitted to the locking jack plug socket  16  so that the locking jack plug socket  16  can transmit the electrical signals to a jack plug engaged with the locking jack plug socket  16 . 
         [0026]    The standard jack plug socket  18  is conventional in design and will not be described in detail. 
         [0027]    Referring now to  FIGS. 1 to 8 , the locking jack plug socket  16  includes a locking arm  32 , a control screw  34  and a pair of pivot mounts  36 . The locking arm  32  is best seen in  FIG. 6  which shows the underside of the locking arm  32 . As shown in  FIG. 6 , a first end of the locking arm  32  is provided with a pair of pivot pins  38 . As shown in  FIG. 1 , the pair of pivot pins  38  co-operate with the pivot mounts  36  to allow the locking arm  32  to pivot around the axes of the pivot pins  38 . As seen in  FIG. 1 , the pivot mounts  36  do not prevent upward movement of the pivot pins  38  out of engagement with the pivot mounts  36 . However, two projections (not shown) are provided on the underside of the intermediate lid  12  so that when the intermediate lid  12  is fixed to the casing bottom  10  as described above, the projections on the underside of the intermediate lid  12  bear against the pair of pivot pins  38  and prevent any upward movement of the pivot pins  38 . In this way, the locking arm  32  is constrained so that only pivoting movement around the axes of the pivot pins  38  is allowed. 
         [0028]    The second end of the locking arm  32  is provided with a locking ring  40 . The locking ring  40  cooperates with the control screw  34 , as described below, to achieve movement of the locking arm  32  between a locking position and a release position. 
         [0029]    As shown in  FIG. 6 , the underside of the locking arm  32  is provided with a frusto-conical recess  42 . This serves a purpose described below. 
         [0030]    The control screw  34  is best seen in  FIGS. 1 ,  4 ,  5 ,  7  and  8 . As seen, for example, in  FIGS. 1 and 4 , the locking screw  34  is engaged, by way of corresponding screw threads, with a nut  44  which is fixed to the bottom wall of the casing bottom  10 . In this way, if the control screw  34  is rotated in a clockwise direction (as seen from above), the control screw  34  moves downwardly into the nut  44 . If the control screw  34  is rotated in an anti-clockwise direction (as seen from above), then the control screw  34  moves upwardly relative to the nut  44 . 
         [0031]    The top end of the control screw  34  is provided with a security formation in the form of a truncated pyramid  46 . This truncated pyramid  46  is shaped so as to engage with a security key (not shown). The security key is used to rotate the control screw  34  either in a clockwise or anti-clockwise direction. 
         [0032]    Immediately below the truncated pyramid  46 , the control screw  34  is provided with a locking disc  48 . The locking disc  48  cooperates with the locking ring  40  of the locking arm  32  to control movement of the locking arm  32  between a locking position and a release position, as will now be described. 
         [0033]    As best seen in  FIGS. 5 and 7 , the locking ring  40  of the locking arm  32  has, on its upper surface, a cam surface  50 . Adjacent to the cam surface  50 , the locking ring  40  of the locking arm  32  also has a stop surface  52 . 
         [0034]    As best seen in  FIG. 8 , the underside of the locking disc  48  of the control screw  34  also has a cam surface  54 . Adjacent to cam surface  54 , the locking disc  48  of the control screw  34  has a stop surface  56  which can be seen in  FIG. 7 . 
         [0035]      FIGS. 5 ,  7  and  8  show the locking arm  32  in a release position.  FIGS. 5 and 8  also show a jack plug  60  which is engaged with, but not locked with, the locking jack plug socket  16 . In the release position of the locking arm  40 , as shown in  FIGS. 5 ,  7  and  8 , the jack plug  60  can be withdrawn from the locking jack plug socket  16  simply by pulling the jack plug  60  out of the locking jack plug socket  16 . 
         [0036]    However, the security key (not shown) can be engaged with the truncated pyramid  46  of the control screw  34  and the security key is then used to rotate the control screw  34  in a clockwise direction (as seen from above). This causes the control screw  34  and the locking disc  48  to move downwardly into/towards the nut  44 . During this process, the cam surface  54  on the locking disc  48  moves against and along the cam surface  50  on the locking ring  40  of the locking arm  32 . The engagement of the two cam surfaces  50 ,  54  and the downward movement of the control screw  34 , moves the locking arm  32  downwardly from the position shown in  FIG. 8 . The distance of movement is relatively small. 
         [0037]    This process continues until the stop surface  56  on the locking disc  48  of control screw  34  contacts the stop surface  52  on the locking ring  40  of the locking arm  32 . After contact between the two stop surfaces  52 ,  56  no further clockwise motion of the control screw  34  is possible. At this point, the locking arm  32  is in the locking position, and this is shown in  FIG. 3 . 
         [0038]    As seen in  FIG. 3 , the jack plug  60  is of conventional design and has a jack plug tip shown at  62 . The jack plug tip  62  has a convex frusto-conical surface indicated at  64 . In the current locking position of the locking arm  32 , the concave frusto-conical surface of the recess  42  of the locking arm  32  (best seen in  FIGS. 3 and 6 ) fits closely against the convex frusto-conical surface  64  of the tip  62  of the jack plug  60 . The two frusto-conical surfaces  42 ,  64  (one being convex and the other being concave) correspond closely in shape and this provides an effective locking mechanism preventing withdrawal of the jack plug  60  from the locking jack plug socket  16 . 
         [0039]    As best seen in  FIGS. 3 and 8 , a bracing rib  66  extends upwardly from the bottom wall of the casing bottom  10  and this bracing rib  66  serves to prevent downward movement of the jack plug  60  which would otherwise reduce the effectiveness of the locking of the jack plug  60  within the locking jack plug socket  16 . It will be appreciated that additional bracing ribs may be provided, either extending upwardly from the casing bottom  10 , or extending downwardly from the underside of the intermediate lid  12 . In this way, any tilting of the jack plug  60  when engaged within the locking jack plug  16  may be prevented. 
         [0040]    In order to unlock the locking jack plug socket  16 , so as to allow removal of the jack plug  60 , the control screw  34  is rotated in an anticlockwise direction whereupon the two cam surfaces  50 ,  54  move against each other back into the unlocking position shown in  FIGS. 5 and 8 . This causes a small upward movement of the locking arm  32  which is sufficient to allow withdrawal of the jack plug  60 . At the rotational position of the control screw  34  shown in  FIGS. 5 and 8 , no further anticlockwise rotation of the control screw  34  is possible due to contact between two additional stop surfaces (not shown). 
         [0041]    As best seen in  FIGS. 3 and 5 , the jack plug  60  is of a type referred to as TRS. In other words, the tip  62  forms a first electrical contact, a ring  68  forms a second electrical contact and a sleeve  70  forms a third electrical contact. As best seen in  FIG. 3 , the locking jack plug socket  16  has first, second and third electrical contacts  72 ,  74 ,  76 . The first electrical contact  72  forms an electrical contact with the tip  62 . The second electrical contact  74  forms an electrical connection with the ring  68  and the third electrical contact  76  forms an electrical connection with the sleeve  70 . Each one of the first, second and third electrical contacts  72 ,  74 ,  76  is spring loaded urging the electrical contacts  72 ,  74 ,  76  against the corresponding part of the jack plug  60 . The electrical contacts  72 ,  74 ,  76  are in electrical connection with the electrical connectors on the underside of the connection plate  30 . 
         [0042]    The upper surface of the intermediate lid  12  is shown in  FIG. 9 .  FIG. 9  also shows two bolts  80  which pass through respective holes in the intermediate lid  12  and are received in the support bosses  22  in order to fix the intermediate lid  12  securely against the casing bottom  10 . As seen in  FIG. 9 , the intermediate lid  12  has three bayonet type slots  82  which cooperate with three corresponding bayonet projections (not shown) on the underside of the outer lid  14  in order to fix the outer lid  14  to the casing bottom  10 . The intermediate lid  12  also has an aperture  84  which corresponds in position with the truncated pyramid  46  of the control screw  34  so that the security key can be passed through the aperture  84  to operate the control screw  34 . 
         [0043]    A slot  86  is also provided in the intermediate lid  12  to facilitate lifting of the intermediate lid  12  out of the casing bottom  10 . 
         [0044]    In operation, the security device is fixed to a fixture using the attachment bosses  20  as described above. In this example, the security device is used to secure a pair of headphones on retail display. The jack plug  60  of the headphones is inserted into the locking jack plug socket  16 . A retail assistant then removes the outer lid  14  by rotating the outer lid  14  so as to reveal the intermediate lid  12 . There is no need to remove the intermediate lid  12 . The retail assistant uses the security key to rotate the control screw  34  in a clockwise direction which causes the locking arm  32  to move from the release position to the locking position as described above. The jack plug  60  is now locked in the locking jack plug socket  16 . The retail assistant replaces the outer lid  14 . 
         [0045]    A potential customer is now able to listen to music through the headphones. In order to do this, a connecting cable (not shown) having a jack plug at each end is used. One of the jack plugs of the connecting cable is inserted into the standard jack plug socket  18  of the security device. The other jack plug of the connecting cable is inserted into the customer&#39;s MP3 player or mobile phone. Electrical signals carried by the connecting cable to the standard jack plug socket  18  are passed to the locking jack plug socket  16  and the music can be heard in the headphones. The locking of the jack plug  60  in the locking jack plug socket  16  prevents theft of the headphones. 
         [0046]    It will be appreciated that the security device need not be as described above and many adaptations may be made while remaining within the scope of the appended claims. 
         [0047]    For example, while the locking mechanism described above has been found to be very effective, any locking mechanism capable of holding a jack plug within a locking jack plug socket may be used. 
         [0048]    In addition, it is not necessary to provide a standard jack plug socket  18 . Instead, the security device may be provided with a jack plug of its own connected to the locking jack plug socket  16  by a cable fixed to the casing. The jack plug of the security device can then be simply inserted into the MP3 player or mobile phone of the customer. 
         [0049]    Alternatively, the security device could be provided with any other type of input, such as a USB socket or USB plug.