Background and Field The invention relates to a lock assembly for sliding doors.

Figure 1 illustrates a known mortise hook lock 11 for sliding doors and the mortise hook lock 11 is installed in a door panel 12 of the door, and includes a strike plate 13 mounted at a door frame 14 adjacent to the door panel 12. The mortise hook lock 11 of Figure 1 includes a spindle 16 attached to a hook latch 17 (see Figure 2) and in Figure 1 , the hook latch is in a retracted position and thus, the door panel 12 is not locked to the door frame 14. The mortise hook lock 11 also includes a coin activated release 15 which includes a coin slot 19 and the coin activated release 15 is attached to the spindle 16 so that rotating the coin activated release 15 also turns the spindle 16 (and thus, the hook latch 17).

Figure 2 illustrates the other side of the door panel 12 and the mortise hook lock 11 includes a handle 18 for turning the spindle 16 and thus extends the hook latch 17 out of the door panel 12. When the door panel 12 is drawn sufficiently close to the door frame 14, to open or lock the door panel 12, the handle 18 is rotated between horizontal and vertical positions to move the hook latch 17 between a hooked position in which the hook latch 17 is latched inside of the strike plate 13 and an unhooked position in which the hook latch 17 is unlatched from the strike plate 13 thus, allowing the door panel 12 to be pushed away from the door frame 14.

It is common for such a mortise hook lock 11 to be used with a door to a toilet cubicle or a communal or shared facility. For example, the handle 18 would be positioned within or inside the toilet cubicle and the coin activated release 15 is then positioned outside of the toilet cubicle. It is also common for the coin activated release 15 to include a colour indicator 20 such as "red" which corresponds to when the handle 18 is turned to latch the hook latch 17 to the strike plate 13 (and thus, the door is locked and the cubicle is occupied) and "green" to indicate that the door panel 12 is unlatched and thus, the cubicle is not occupied. Under normal use, the mortise hook lock 11 is thus operated by turning the handle 18 by a user using the cubicle but if the user is an elderly or infirm person (for example, the person slipped and fell and is unconscious), sometimes this may not happen. Thus, in emergency situations, the door panel 12 may be unlocked from the outside by using a coin or screw driver to engage the coin slot 19 and rotating the coin slot 19 to rotate the spindle 16 and the hook latch 7 out of the strike plate 13 to the unlock position.

In this way, the mortise hook lock 11 provides a privacy function with the coin slot release 15 as an emergency release should the occupant require assistance and is unable to unlock the door panel 2.

However, it may not be always possible to unlock the door panel 12 by rotating the coin slot release 15 from the outside. For example, due to wear and tear, malfunction to the hook latch 17 or changes to the position of the door panel 12 in relation to the door frame 14 when the door panel 12 is in the lock position may prevent the door panel 12 from being unlocked using the coin slot release 15. When that happens, drastic actions may thus be needed to reach the occupant trapped inside the cubicle and these may involve breaking the mortise hook lock 11 or to pry open the door panel 12 forcefully. Such methods are not preferred since it is time consuming and may have an adverse effect since it is already an emergency situation to begin with, not to mention the possible damage to the mortise hook lock 11 , the door panel 12 and the door frame 14.

It is thus desirable to provide a lock assembly which addresses at least one of the disadvantages of the prior art and/or to provide the public with a useful choice. Summary

In a first aspect, there is provided a lock assembly for a sliding door comprising a latch arranged to engage a latch engagement member mounted to an adjacent door frame; a rotatable spindle insertable into a lockset hole of the door and connectable to the latch in which the rotatable spindle is arranged to move the latch angularly between a first position in which the latch is engaged with the latch engagement member, and a second position in which the latch is disengaged from the latch engagement member; and a handle for rotating the spindle between the first and second positions from a first side of the door; wherein, in the first position, an axial movement of the spindle is arranged to displace the latch linearly to enable the latch to be disengaged from the latch engagement member. If the handle is unable to unlock the door, the described embodiment allows a much more reliable way of disengaging the latch from the latch engagement member in the event of an emergency.

Preferably, the lock assembly may further comprise a first escutcheon arranged adjacent to the latch and to be attached to the spindle, wherein the first escutcheon is detachably attached to the first side of the door. The lock assembly may include a cap arranged to be attached to the first escutcheon.

The lock assembly may further comprise an emergency release mechanism for rotating the spindle between the first and second positions from a second side of the door. This emergency release mechanism thus provides an initial emergency mechanism to open the door and in the event this emergency release mechanism malfunctions or fails to open the door, the spindle may then be actuated to unhook the latch.

The lock assembly may comprise a second escutcheon arranged to be mounted to the second side of the door and enables an end of the spindle to protrude therethrough and the emergency release mechanism may be arranged to be detachably attached to the second escutcheon.

Preferably, the emergency release mechanism may include a catch for detachably coupling to the spindle.

The latch engagement member may form part of the lock assembly or may not.

The lock mechanism may be installed to a door and the door sold with the lock mechanism. In this respect, a second aspect relates to a sliding door comprising the lock assembly as described earlier.

The lock mechanism may also be produced and sold by itself, and as a result, it is possible that the lock mechanism is retrofitted to a door. This forms a third aspect, in which there is provided a method of retrofitting a door with a lock assembly, and the method comprises inserting a rotatable spindle through a lockset hole of the door; connecting the spindle to a latch so that rotating the spindle moves the latch angularly between a first position in which the latch is engaged with a latch engagement member mounted to an adjacent door frame, and a second position in which the latch is disengaged from the latch engagement member; attaching a handle to the spindle in order to rotate the spindle between the first and second positions from a first side of the door; and attaching an emergency release mechanism to the spindle for rotating the spindle between the first and second positions from a second side of the door; wherein, in the first position, an axial movement of the spindle is arranged to displace the latch linearly to enable the latch to be disengaged from the latch engagement member.

The method may comprise attaching an emergency release mechanism to the spindle for rotating the spindle between the first and second positions from a second side of the door. In this way, there is a dual emergency release. Preferably, the method may further comprise mounting the latch engagement member to the adjacent door frame.

It should be appreciated that features relevant to one aspect may also be relevant to the other aspects.

Brief Description of the Drawings An exemplary embodiment will now be described with reference to the accompanying drawings, in which:

Figure 1 is a partial perspective view of a door panel from one side and a door frame installed with a known mortise hook lock (with some parts exploded and some internal parts shown in broken lines);

Figure 2 is a partial perspective view of the door panel from the other side with the mortise hook lock in a latch position;

Figure 3 is a partial cross-sectional view of a door panel mounted with a lock assembly according to a preferred embodiment;

Figure 4 is an exploded view of the lock assembly of Figure 3;

Figure 5 is a partial perspective view of a door frame or jamb which cooperates with the door panel of Figure 3;

Figure 6 is a partial view from one side of the door panel of Figure 3 which illustrates an emergency release mechanism;

Figure 7 is a partial view from the other side of the door panel of Figure 3 which illustrates a latch of the lock assembly being engaged with a latch engagement member;

Figure 8 is a partial view of a first template for creating holes to one side of a door for ease of retrofitting or installing the lock assembly of Figure 3 to the door; and

Figure 9 is a partial view of a second template for creating holes to another side of a door for ease of retrofitting or installing the lock assembly of Figure 3 to the door. Detailed Description of Preferred Embodiment

Figure 3 is a partial cross-sectional view of a door panel 102 which forms part of a door 100. In this embodiment, the door panel 102 is a sliding type door and is installed with a lock assembly 200. Figure 4 illustrates an exploded view of the lock assembly 200 of Figure 3.

The lock assembly 200 comprises a rotatable spindle 202 inserted into a lockset hole 104 of the door panel 102. The rotatable spindle 202 is arranged to rotate radially and also movable axially by sliding along the lockset hole 104. The door panel 102 further includes two attachment holes 106,108 arranged on respective sides of the lockset hole 104 and a bore 110. The attachment holes 106,108 are through holes which extend from one main surface 102a of the door panel 102 to the other main surface 102b.

The lock assembly 200 includes a latch 204 having a longitudinal axis 204a and is fixedly coupled at one end to the spindle 202 near a first end 202a of the spindle 202 and rotation of the spindle 202 thus rotates the latch 204 in the same direction. The first end 202a of the spindle 202 is coupled to a handle 206 which is used by a user to lock or unlock the door 100. In other words, rotation of the handle 206 rotates the spindle 202 which in turn moves the latch 204 accordingly.

The lock assembly 200 also includes an escutcheon 208 which carries a stud 210 for insertion into the bore 110, and two internally threaded sleeves 211 for mating the respective threaded screws 220 (which will be explained later). The stud 210 fits snugly within the bore 110, and together with the screws 220 being threaded into the sleeves 211 , these allow the escutcheon 208 to be attached to the first main surface 102a of the door panel 102 while hiding the latch 204 from normal view. The escutcheon 208 is also coupled to the spindle 202 near the first end 202a and the escutcheon 208 is detachable from the door panel 102 by a slight pushing force asserted on the spindle 202 which will be further explained later. The lock assembly 200 further includes a cap 212 which is attached to the escutcheon 208 by a built-in clip (not shown).

On the second main surface 102b, the lock assembly 200 includes an inner escutcheon 214 with a main aperture 215 (not shown in Figure 4 but see Figure 8) and two side apertures 216 corresponding to the lockset hole 104 and the attachment holes 106,108 respectively. The main aperture 215 enables the spindle's second end 202b to protrude through to engage an emergency release mechanism 218, whereas the side apertures 216 allows an attachment device, such as the screws 220, to be used to attach the inner escutcheon 214 to the second main surface 102b via the attachment holes 106,108. Specifically, the screws 220 are threaded through the attachment holes 106,108 and protrude beyond the first main surface 102a to enable the ends of the screws 220 to be threaded into the respective sleeves 211.

The emergency release mechanism 218 has a generally disc-shape body with a rotatable coin slot 222 with a coin slot catch 224 for attaching to the second end 202b of the spindle 202. When the coin slot 222 is rotated, this causes the spindle 202 to rotate correspondingly and at the same time change a colour indicator 226 (see Figure 6) to reflect a status. For example, if the lock assembly 200 is used with a door to a toilet cubicle, the handle 206 would be located inside the cubicle whereas the emergency release mechanism 218 would be located outside of the cubicle and the colour indicator 226 change thus indicates whether the toilet cubicle is occupied or empty.

Figure 5 illustrates a door frame 112 or door jamb which cooperates with the door panel 102 and forms part of the door 100. The lock assembly 200 also includes a latch engagement member 228 mounted to an edge 114 of the door frame 114. In this embodiment, the latch engagement member 228 is substantially rectangular or it may be configured as a knob.

When the door panel 102 is drawn sufficiently close, moving the handle 206 angularly across a ninety degree angle (for example, between a vertical position shown in Figure 4 to a horizontal position shown in Figure 7) extends the latch 204 angularly to latch onto a surface of the latch engagement member 228, as shown in Figure 7. In this way, this prevents the door panel 102 from being pushed away from the door frame 112 (i.e. move in a direction substantially parallel to the longitudinal axis 204a of the latch 204) and thus, the door 100 is considered to be in a locked position. To open the door 100, the latch 204 is lifted by turning the handle 206 angularly and the door panel 102 may thus be slide opened. In the locked position as shown in Figure 7, and during an emergency, the door 100 may be opened from the outside (i.e. Figure 6) by using the emergency release mechanism 218. Specifically, a coin or screwdriver may be used to rotate the coin slot 222 to lift the latch 204 from the outside. If this fails, for example due to malfunction of the emergency release mechanism 218 or misalignment of the door panel 102 and the door frame 112, the present embodiment provides a further emergency release to open the door 100.

From the outside, the emergency release mechanism 218 is detached from the inner escutcheon 214 and also the spindle 202. The screws 220 are then unscrewed to decouple the escutcheon 208 from the screws 220. The user then pushes the second end 202b of the spindle 202 axially or inwardly (i.e. the axial direction is indicated as AA in Figure 4, which is substantially perpendicular to the longitudinal axis 204a of the latch 204) with a bit of force in order to detach the stud 210 of the escutcheon 208 from the bore 110, and this also displaces the latch 204 (as well as the handle 206 and the escutcheon 208) linearly until it is free from the latch engagement member 228. As a result, the door panel 102 is unlatched from the door frame 112 and the door 100 may thus be opened.

In this way, the lock assembly 200 offers a dual emergency mechanism to open the door 100 in an emergency to reach the person trapped inside the door 100. Indeed, the lock assembly 200 is simple to operate and allows the door 100 to be opened from the outside in an emergency without using any tool, or with commonly available tools, if the coin slot 222 malfunctions. With most of the parts of the lock assembly 200 located on the outside of the door panel 102 (in particular the latch 204), instead of being embedded or located within the door panel 102, this also allows easier maintenance of the lock assembly 200. Of course, while the present embodiment describes the latch 204 etc being mounted to the first main surface 102a (or the second main surface 102b) of the door panel 102, it is possible that a recess (not shown) is created on the first main surface 102a and the latch 204 sits within the recess to enable the cap 212 to be flushed with the first main surface 102a of the door panel 102. The same arrangement may be created for the emergency release mechanism 218.

It is envisaged that the lock assembly 200 may be retrofitted to existing doors with ease since most of the parts are external of the door 100. If the existing doors already have a lockset hole (for the spindle 202), then minimum drilling may be carried out. On the other hand, if a new lockset hole needs to be created (for existing/new doors), then two templates 250,260 may be used for convenience, as illustrated partially in Figures 8 and 9.

The first template 250 has circular guide holes 252 with sizes and relative distances to correspond to the lockset hole 104 and the two attachment holes 106,108. Likewise, the circular guide holes 252 also correspond to the main aperture 215 and side apertures 216 of the inner escutcheon 214, which is also shown in Figure 8 for easier reference. The first template 250 may thus be used to mark the location of the lockset hole 104 and the two attachment holes 106,108 and then these holes are drilled.

The second template 260 is intended for the second main surface 102b of the door panel 102a and the second template 260 also includes a set of guide apertures 262,264 which correspond to the lockset hole 104, the two attachment hole 106,108 and the bore 110. If the lockset hole 104 and the two attachment holes 106,108 have been created (using the first template 250), then the second template 260 may be aligned to these holes 104,106,108 and used to create the bore 110. Needless to say, this would enable the stud 210 of the escutcheon 208 to be detachably affixed to the bore 110. As a reference, the escutcheon 208 is also illustrated in Figure 9. It should also be appreciated that only the second template 260 is needed for drilling the holes and the first template 250 may not be used.

With the lockset hole 104, the two attachment holes 106,108 and the bore 110 formed, the lock assembly 200 may be installed or retrofitted with relative ease. The spindle 202 is inserted through the lockset hole 104 and attached to the latch 204 as well as the escutcheon 208 near the first end 202a of the spindle 202. The stud 210 of the escutcheon 208 is then inserted into the bore 110 to hold the spindle 202 to the door panel 102. The inner escutcheon 214 is next screwed into place using the screws 220 which extends through the attachment holes 106,108 and threaded into the sleeves 211 to secure the spindle 202, the latch 204 and the escutcheon 208 to the door panel 102. The emergency release mechanism 218 clipped to the inner escutcheon 214 and the catch 224 attached to the second end 202b of the spindle 202. The cap 212 is then clipped onto the escutcheon 208 with the first end 202a of the spindle 202 protruding through a corresponding hole in the cap 212 in order for the first end 202a of the spindle 202 to be attached to the handle 206. The latch 204 may thus be extended outwardly or retracted by rotating the handle 206 and in the extended position, the corresponding position of the latch engagement member 228 may be marked on the door frame 112 and the latch engagement member 228 mounted using any conventional means.

The described embodiment should not be construed as limitative. For example, while not described, the lock assembly 200 may have stoppers to limit the rotation of the handle/spindle 206/202. Also, the materials used in the described embodiment may be in any suitable material such as PVC or metals. For example, the screws 220 may be plastic or metal. The spindle 202, the latch 204, the handle 206 and the latch engagement member 228 are preferably made of metal to minimize wear and tear, and warpage.

It should be appreciated that other forms of fasteners, other than screws 220 may be used, and likewise for the stud 210 too. The handle 206 may include any suitable shapes and sizes and includes ones which are activated by a user's thumb or fingers. It is also envisaged that the entire emergency release mechanism 218 need to be detachable if the mechanism 218 is provided. On the other hand, it is envisaged that there may not be the emergency release mechanism 218 (i.e there is no coin slot 222) and instead, in the event of an emergency, it would be necessary to gain access to the spindle 202 in the first instance to unlock the latch 204. In the described embodiment, the latch 204 includes a hook for latching on to an outer surface of the latch engagement member 228 but other structures are possible. It is also envisaged that the colour indicator 226 may be omitted, or change to other forms of indications (eg. text or images).

Having now fully described the invention, it should be apparent to one of ordinary skill in the art that many modifications can be made hereto without departing from the scope as claimed.