Patent Abstract:
There is provided a device ( 10 ) for opening a security screen ( 12 ) locked by a latch member ( 130 ). The device ( 10 ) comprising telescopically extending members ( 14,16,18 ) having a striking member ( 40 ), the striking member ( 40 ) being contactable with the latch member ( 130 ) in use to release the latch member ( 130 ) when the telescopically extending members are in an extended position.

Full Description:
TECHNICAL FIELD  
         [0001]    The present invention relates to a device for opening a security screen.  
         BACKGROUND OF THE INVENTION  
         [0002]    The use of security screens made, for example, from aluminium mesh, is widespread and is a known and an accepted economical way to secure windows and the like from intruders. There are a number of methods for securing such conventional screens to a building. One way is to have a screen which is fixedly attached to the building, the screen being unopenable from either the outside or the inside of the building. These types of screens have the disadvantage that whilst they may act as an effective deterrent to intruders, they can pose a fire hazard as it is not possible to open them from the inside in the event of an emergency, thereby precluding the window to which the screen is attached from acting as an escape route.  
           [0003]    It is known to have screens which are openable from, for example, the inside of the building to which they are attached. Such screens may include a keylock to secure the screen and also render it openable in the event of an emergency Such screens suffer the disadvantage that, should exit in an emergency be necessary, it may be difficult to open the screen as valuable time may be lost in locating the key, particularly if visibility is impaired for example due to smoke. Once found, in such circumstances it may also be difficult and time consuming to locate the key in the actual lock to unlock the screen.  
           [0004]    To overcome the problems outlined above, some keyless systems have been developed in which a lock for locking the screen is located in a box adjacent the frame of the window over which the screen is attached, the lock being openable by depression of a member which unlocks the locking member. The problems with such systems are that it is generally possible for the box, and therefore the screen, to be opened from the outside by an intruder using either an implement such as a pen or coathanger, or a person having small enough hands to reach through an opening in the screen, open the box and deactivate the luck thereby enabling the screen to be opened and entry to the building. It is typical for such boxes to have an openable cover covering the locking mechanism which is usually held shut by means of VELCRO (RTM) or the like. One way of overcoming the aforementioned problems with such screens has been to modify the screen itself to include additional bars extending across the screen but this may considerably reduce the amount of daylight which can pass though the screen.  
         OBJECT OF THE INVENTION  
         [0005]    It is the aim of the present invention to substantially overcome or ameliorate at least one of the above disadvantages, or at least to provide a useful alternative.  
         SUMMARY OF THE INVENTION  
         [0006]    According to the present invention in a first aspect there is provided a device for opening a security screen locked by a latch member, the device comprising a telescopically extending member having a striking member, the striking member being contactable with the latch member in use to release the latch member when the telescopically extending member is in an extended position.  
           [0007]    Preferably, the telescoping member is pivotable about a pivot member to move the telescoping member between a rest position and an operating position.  
           [0008]    Preferably, the telescoping member comprises a first member and a second member, the second member being telescopically receivable in and retractable from the first member, the striking member being engagable with an engaging member connected to the first member in the extended position.  
           [0009]    In a preferred embodiment the striking member is a threaded, and preferably comprises a rod, and the first and second members arc preferably tubular sections.  
           [0010]    Preferably, the second member has an internal threaded section for threadably engaging the threaded striking member, the threaded striking member being extendable out of the second member on rotation of the first member relative to the second member. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings wherein:  
         [0012]    [0012]FIG. 1 is a schematic side elevation of the opening device in the extended position;  
         [0013]    [0013]FIG. 2 is a cross-sectional plan view of the device of FIG. 1 for an inwardly opening screen which is in the locked position;  
         [0014]    [0014]FIG. 3 is a perspective view of a portion of the device of FIGS. 1 and 2;  
         [0015]    [0015]FIG. 4 is a cross-sectional plan view of the device of FIG. I for an inwardly opening screen which is in the unlocked position;  
         [0016]    [0016]FIG. 5 is a cross-sectional plan view of the device of FIGS.  1  to  4  as viewed from the centre of the screen;  
         [0017]    [0017]FIG. 6 is a cross-sectional plan view of the device of FIG. 1 for an outwardly opening screen which is in the locked position; and  
         [0018]    [0018]FIG. 7 is a perspective view of an alternate embodiment of the opening device of FIG. 1 for an outwardly open screen. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    FIGS.  1  to  5  show an opening device  10  for opening a security screen  12  located on the inside of a building, extending over, for example, a window, the screen  12  being inwardly openable, The opening device  10  comprises a first outer tube  14 , a second inner tube  16 , a third tube  18  and an inner rod  20 . The first and third tubes  14  and  18  have a square cross-section, and the second tube  16  and inner rod  20  have a circular cross-section. The inner rod  20  is threaded externally. The inner rod  20 , and third and second tubes  18  and  16  are telescopically received within the first outer tube  14 .  
         [0020]    An internal block  22 , which may be formed from nylon, is located adjacent a first flee end  24  of the third tube  18  and is wholly contained within the third tube  18 . A threaded internal bore  26  extends tough the internal block  22  in a direction parallel to the longitudinal axis  28  of the third tube  18 . The inner rod  20  extends through the third tube  18  and the headed outer portion of the inner rod  20  engages with the threads defining the internal bore  26  of the internal block  22 , A pivot pin  30  extends through an aperture in the internal block  22  and correspondingly aligned apertures in the third tube  18 . The pivot pin  30  is attached to a housing extrusion  32  containing the locking mechanism  34 .  
         [0021]    Attached to one end  36  of the inner rod  20  is a drive section  38  which has a square cross-section, The other end  40  of the inner rod  20  which is adjacent the internal block  22  acts as a contact member for depressing the locking mechanism  34 , the operation of which is described in detail below.  
         [0022]    The second inner tube  16  is telescopically slidable with respect to the third tube  18  along die longitudinal axis  28  of the respective tubes, and inner rod  20 , the inner rod  20  being telescopically receivable within the second tube  16  and the second tube being telescopically receivable within the third tube  18 . The second tube  16  has a bevelled peripheral edge  42  at one free end  44  thereof. The bevelled edge  42  prevents the second tube  16  from being slidably removed from the inner rod  20  as the bevelled edge  42  contacts a flange portion  46  of the drive section  38  attached to one end  36  of the inner rod  20 , preventing further longitudinal movement, As shown in FIG. 3, the free end  44  of the second tube  16  has a deformed square cross-section enabling it to engage with the drive section  38  attached to the inner rod  22 .  
         [0023]    The first outer tube  14  telescopically receives the third tube  18  and the inner rod  20 . The second tube  16  is fixedly retained within the first outer tube  14 . An end section  46  is attached to a free end  48  of the first outer tube  14 . The end section  46  has a square cross-section. A pin  50  extends through correspondingly aligned apertures in the end section  46  and second tube  16  at a position adjacent the end  52  of the second tube  16  opposite to the end  46  of the second tube  16  which abuts the drive section  38  attached to the inner rod  20 . The second tube  16  is thereby retained in position relative to the first tube  14 . A bush  54  made from, for example nylon, is located adjacent the free end  48  of the first outer tube  14  and is wholly retained within the first tube  14 . The second tube  16  extends through a longitudinally extending bore  56  which extends through the bush  54 . A first end  55  of the bush  54  is flush with the end  48  of the first tube  14  and abuts the end section  46  attached to the first tube  14 . A retaining clip  58  extends through correspondingly aligned apertures in the second tube  16  such that the retaining clip  58  is located adjacent the other end  60  of the bush  54 .  
         [0024]    When not being used to unlock the locking element  130 , the opening device  10  of the present invention may be stored in a cavity  158  located in an upright position extending adjacent or within the screen housing  122  of the security screen  12 . The stored position of the third tube  18  is shown in phantom in FIG. 5 and denoted by reference numeral  18 ′. The opening device  10  is pivotable about the pivot pin  30  which extends through an aperture in the end section  22 . In the position ready for use to unlock the locking member  130 , as shown in FIG. 5, a rest pin  155  acts as a stop to prevent the locking device  10  from being pivoted beyond the desired position about pivot pin  30 . The rest pin  155  abuts the outer surface of the third tube  18 , as shown in FIG. 5 to prevent further rotation.  
         [0025]    The opening device  10  of the present invention is suitable to unlock a conventional locking device  34  depicted in connection with the opening device  10  of the present invention in FIGS.  2  to  5  for inwardly opening security screens and similar type devices  34   a  in FIGS.  6  mid  7  for an outwardly opening security screen. The locking device  34  comprises a locking element  130 , typically an aluminium extrusion, which is rotatably located and retained within a receiving member  132  attached to the housing extrusion  32 . In FIG. 7, two parts  130   a ,  130   b  comprise the locking element both of which are pivotable about separate members  132  located on the housing extrusion  32 . In FIGS.  1  to  7  a portion of the locking element  130  contacts a compression spring member  136  also located with the housing extrusion  32 . A generally U-shaped member  137  has two arm portions  138  and  139  and a base section  140 . The first arm portion  138  is shorter in length than the second arm portion  139  which acts as a barrier to external implements such as a jemmy which could be used by an intruder seeking to unlock the locking member  34  to open the security screen  12 .  
         [0026]    The U-shaped member  137  is attached to an edge portion of the screen housing  122  by means of a rivet, for example a pop rivet  150  or could be integrally formed as in FIG. 7. The expanded metal mesh screen  12  is fixed to the screen housing  122 .  
         [0027]    The screen housing  122  is held in the locked position as shown in FIG. 2 and  7  by an abutment member  135  which is part of the locking clement  130  which abuts the first arm portion  138  of the U-shaped member  137 . In this locked configuration, the compression spring  136  is in its rest position. As seen in FIGS.  1  to  7  the spring  136  forces the locking element into abutment against the first arm portion  138 .  
         [0028]    To open the locking member  130  and thereby unlock the screen  12  using the opening device  10  according to the present invention, the procedure is as follows. The locking device  10  is pivoted about pivot pin  30  to remove the device  10  from its upright storage position within a cavity  158  in or adjacent to the screen housing  122 . The opening device  10  is moved in an arcuate path  160  about the pivot pin  30  as shown in FIGS. 1 and 5 until the first, second and third tubes  14 ,  16 ,  18  and inner rod  20  lie in a plane substantially perpendicular to the plane of the screen  12 . Further pivotal movement beyond this position about pivot point  30  is inhibited by the contact of the third tube  18  against the rest pin  15 , as shown in FIG. 5.  
         [0029]    The operator extends the opening device  10  by telescopically extending the first outer tube  14 , and thereby the second tube  16  attached thereto, relative to the third tab  18 . In the fully extended position, in which the length of the device  10  could be, for example, one meter in length, the bevelled edge  42  of the second tube  16  contacts the flange portion  46  of the drive section  38  attached to one end  36  of the inner rod  20  preventing further longitudinal extension. Once the device  10  is fully extended, the operator turns the first tube  14  in a clockwise direction. This motion has the effect of rotating the inner rod  20  as rotation of the first tube  14  causes rotation of the second tube  16  attached thereto and the end  44  of the second tube  16  engages the drive section  38  attached to the inner rod  20  causing rotation of the inner rod  20 . This rotation of the inner rod  20  can only occur when the device is in the extended position with the end  44  of the second rod  16  engaging the drive section  38 . The rotation of the inner rod  20 , which is threadably engaged with the threads defining the aperture  26  in the internal block  22 , allows the threaded inner rod  20  to extend outwardly of the third tube  18 . The end contact surface  40  of the inner rod  20  contacts the locking element  130  causing it to depress the compression spring  136  and thereby rotate about the receiving member  132 . This rotation of the locking element  130  frees the locking portion  135  from abutment against the first arm portion  138  disengaging the locking mechanism from the screen housing  122  allowing the screen to be opened.  
         [0030]    After use, the device  10  may be retracted and pivoted about pivot pin  30  to be stored in the cavity  158 . The cavity  158  preferably is 30 mm to 35 mm wide/deep.  
         [0031]    [0031]FIGS. 6 and 7 show the device  10  for use in the opening of an outwardly opening security screen and the same reference numerals have been used to denote like elements as used with the inwardly opening screen shown in FIGS.  1  to  5 . The same method as described above with respect to the inwardly opening screen  12  applies, the only difference for FIG. 6 being the shape of the locking member  130 . The difference for FIG. 7 being that locking member  130  is comprised of two parts  130   a  and  130   b  both of which pivot about separate members  132  located on the housing extrusion  32 .  
         [0032]    It will be seen that the device  10  of the present invention has a number of advantages. Firstly, to operate the opening device  10  it is necessary to have the device  10  in the extended position which, as shown in FIG. 1, is beyond the reach of an intruder  200  rendering it virtually tamperproof from the outside. The present invention also allows a quick keyless opening of the security screen  12  from, for example, the inside and enables exit though the window opening in the case of an emergency. It may be possible to open the device  10  in approximately  5  seconds. Also, the dimensions of the opening device  10  are such that minimal intrusion into the space surrounding the window occurs. The device  10  and method of opening the security screen  12  can be installed and applied to existing security screens with minimal alteration necessary to the existing screen. In such cases, no alteration to the height of the screen need be made, merely the width of the screen could be reduced by, for example 35 mm to house the locking device  10  in a cavity  155  in the stored position. The security screen  12  may be easily opened using the device  10  for the purposes of cleaning and maintenance of the window and/or screen  12 . The device  10  is economical having low maintenance and installation costs. Also, the device  100  may be manufactured to fit any height of opening such as a window or door to which a security screen  12  is to be attached, for example from a 600 mm wide/high opening to an 8 meter wide/high opening. Also, the location of operation of the device  10  may be arranged at any suitable and desired height The device  10  is easy to operate and operating instructions may be printed on a visible face thereof.  
         [0033]    Various modifications will be evident to the person skilled in the art. For example, whilst the device  10  has been described with reference to a security screen for windows, the device could be equally applicable to such screens located adjacent doors or other openings. Also, the dimensions given are merely preferred examples and could vary. Preferred construction materials for the device  10  are aluminium extrusions, stainless steel, plastics material and spring steel.

Technology Classification (CPC): 4