Technical Field

The present invention relates to electronic locking arrangements for doors windows or the like and to a magnetic field generator for use in electronic locking arrangements.

Summary of the Invention

In a first aspect the present invention provides a magnetic field generator for use in a locking arrangement for locking a door or window in association with an adjacent building element including: a permanent magnet; a housing portion for receiving the magnet; an adjustment mechanism for allowing adjustment of the position of the magnet in the housing.

The adjustment mechanism may allow for adjustment of the depth of the magnet in the housing.

The adjustment mechanism may include a threaded rod, the magnet is mounted on the threaded rod and adjustment of the position of the magnet is effected by rotating the rod.

The magnet may be biased towards one end of the rod by a spring.

In a second aspect the present invention provides a strike plate including a magnetic field generator according to the first aspect of the invention.

In a third aspect the present invention provides a locking arrangement for selectively locking a door or window in association with an adjacent building element, the arrangement including: an electrically operated lock; and a magnetic field generator according to the first aspect of the invention; the lock and magnetic field generator are mounted to respective ones of either the door or window or the adjacent building element; the lock is operable between a locked condition and an unlocked condition, in the locked condition the door or window is engaged with the adjacent building element by the lock to resist opening of the door or window; the lock includes a magnetic field detector and the lock is arranged to move from the unlocked to the locked condition based on the strength of magnetic field detected by the magnetic field detector.

The lock may include a locking tongue which is provided with a hook formation which engages with the adjacent building element. Brief Description of the Drawings

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a locking arrangement incorporating a magnetic field generator according to an embodiment of the invention;

Figure 2 is a side view of the locking arrangement of figure 1 with the lock adjacent the strike plate; and

Figure 3 is an enlarged view of detail A of figure 2.

Detailed Description of the Preferred Embodiment

Referring to figure 1, a locking arrangement 10 is shown for use in locking a sliding door to an adjacent building element such as a door frame. The locking arrangement includes an electronic lock 40 and a strike plate 20.

Strike plate 20 includes a magnetic field generator 30 which is shown in exploded view and comprises a housing portion in the form of well 38, an annular permanent magnet 34 and an adjustment mechanism including a threaded rod in the form of screw 32, and a biasing spring 36. The screw 32 is threadedly engaged with an aperture provided in the base of well 38 (see figure 3). The head of screw 32 is accessible through aperture 24 of faceplate 21 to rotate the screw to adjust the position of magnet 34 in well 38 as will be later described.

Lock 40 is of similar construction to the lock described in applicant's published international patent application WO2012/155177, the contents of which are incorporated herein by reference. Lock 40 differs to the lock described in

WO2012/155177 in that the locking tongue includes a hook formation 42 which is arranged to rotate outwardly to enter aperture 22 of strike plate 20. The hook formation engages with the reinforcing block 23 of strike plate 20 to retain the lock 40 in engagement with the strike plate (see figure 2). The lock 40 is arranged to be operated back to the unlocked condition by either cutting external power to the lock, or by sending a command signal to the lock, depending upon the configuration adopted at the time of installation and the nature of any building control system in use.

The above described locking arrangement is primarily intended for use with sliding doors. The strike plate 20 is affixed to the edge of a door and the lock 40 is mounted into the door frame so that the locking tongue of lock 40 corresponds with the aperture 22 in strike plate 20.

In order for the locking arrangement 10 to function correctly, the lock 40 must be brought up close to strike plate 20 before the locking tongue rotates outwardly. If the locking tongue were to rotate outwardly before the door is closed then proper engagement with the strike plate cannot be achieved.

Referring to figure 3, control of the operation of the lock is based on the output of a magnetic field detector in the form of hall effect sensor 44. When the lock 40 is brought into proximity of the strike plate 20, the hall effect sensor detects the magnetic field produced by the permanent magnet 34. Lock 40 is arranged so that, when a magnetic field with a strength above a particular threshold is detected, the lock 40 moves to the locked condition.

The screw 32 of the magnetic field generator is rotated to adjust the depth of the magnet in well 38. This has the effect of varying the strength of the magnetic field detected at the hall sensor 40. If the magnet is moved deeper into the well (i.e. in a direction away from lock 40), then the magnetic field strength is made weaker. If the magnet is moved in the other direction (towards lock 40) then the magnetic field becomes stronger.

The position of the magnet 34 is adjusted so that the threshold of output of the hall effect sensor is reached when the outer surface of lock 40 is approx. 1 to 2mm away from the outer surface of faceplate 21 of strike plate 20. This adjustment is made at the time of the installation in the following manner:

1. Install strike plate 20 and lock 40.

2. Screw in screw 32 to its fullest extent to generate weakest magnetic field.

3. Close door. It expected that lock 40 will not detect a sufficiently strong

magnetic field and so will not operate.

4. Open door and turn screw by one or two turns to move magnet outwardly.

5. Close door and repeat adjustment of screw as necessary until operation of lock occurs when the outer surface of lock 40 is approximately 1 to 2mm from the outer surface of faceplate 21.

Although the arrangement above has been described with reference to sliding doors it could also be used in relation to hinged doors.

Although the arrangement above has been described with reference to doors it could also be used in relation to windows.

Although the arrangement described above utilised a magnetic field detector in the form of a hall effect sensor, other embodiments may use different types of detector such as a reed switch.

It can be seen that embodiments of the invention provide at least the following advantages:

• Differences in magnet strengths or sensor sensitivities can be accommodated by a screw operated adjustment mechanism.

• The activation point of an electronic lock can be easily adjusted.

Any reference to prior art contained herein is not to be taken as an admission that the information is common general knowledge, unless otherwise indicated.

Finally, it is to be appreciated that various alterations or additions may be made to the parts previously described without departing from the spirit or ambit of the present invention.