One form of such a handle mechanism is disclosed in GB-A-2292969, which is a push and turn mechanism where the handle is rotatably mounted on a base, which is fixed to a window, the handle being provided with a push button incorporating a lock. When the lock is opened by a key. the push button may be depressed to release a latching mechanism to allow the handle to be turned and the window to be opened. A disadvantage of the mechanism described in this reference is the complex nature of the latching mechanism.

Another form of handle mechanism is disclosed in EP-A-0732471 which is also a push and turn mechanism where the handle is rotatably mounted on a base and having a push button mechanism. The push button may be depressed to release a latch or bolt element mounted in the base of the handle mechanism, thereby to allow the handle to be turned.

It is a requirement for packing and shipping purposes that the handle mechanism should stand upright as small an amount as possible from the wing or sash on which it is mounted, so that the wings can be packed closely together, without risk of damage to the handle.

Accordingly it is an object of the invention to provide a lockable handle mechanism for a wing or sash which stands upright from the wing a reduced amount in height, and which is inexpensive and reliable in construction.

The present invention provides a handle mechanism for a wing, comprising a base member for mounting to the wing, and a handle pivotably mounted to the base member for rotation to selectively lock and unlock the wing, a cassette unit secured within the handle, the cassette unit including a push button for actuating a handle locking member, the handle locking member being engagable in a recess for locking the handle to the base member in a parked position of the handle, and the push button being manually depressible to move the handle locking member from the recess to enable rotation of the handle from the parked position, and the cassette including a coupling means for coupling the handle locking member to the push button and providing a mechanical advantage so that movement of the push button creates a corresponding larger movement of the handle locking member to release the handle locking member from said recess.

As preferred the coupling means is mounted both for translation and rotation in response to movement of the push button for the requisite release action.

In a preferred embodiment. the handle locking member is pivotably mounted within the base member and projects from the base member into said recess which is formed in an underside of the handle. The coupling means comprises a lever mounted within the handle and coupled to the push button so that depression of the push button causes translation of the lever and rotation of the lever about one end thereof so that the other end of the lever engages and presses the handle locking member out of engagement with said recess. A ratio of movement of over 1 can be obtained by this means which permits the handle mechanism to be made substantially more compactly than those of the prior art.

In another embodiment, said coupling means comprises a pivoting means which is incorporated in the handle locking member. The handle locking member is mounted in the handle and engages with said recess which is formed in said base member. Said pivoting means permits both rotation and translation of the locking member so that as the push button mechanism is depressed, the locking member is rotated upwardly from the recess together with translatory sliding movement, whereby to fully release from the recess in the base member. The pivoting means comprises one or more first pins attached to one end of the locking member and slideable in vertical guide slots, and one or more second pins spaced from the first pins and mounted in guide slots extending transversely of the push button mechanism so that upon depression of the push button mechanism, the locking member rotates about the second pins in an upwards direction and in addition slides outwardly away from the locking mechanism. The position of the first pins relative to the second pins provides a mechanical advantage at the end of the locking member to provide a greater movement of the locking member in order to clear the recess in the base member. The mechanical advantage permits the required degree of upward movement whilst minimising the overall height required for the locking/unlocking movement.

Brief Description of the Drawings Preferred embodiments of the invention will now be described with reference to the accompanying drawings wherein:- Figure 1 is a schematic plan view of the lockable handle mechanism according to a first embodiment of the invention; Figure 2 is a sectional view of a cassette unit incorporated in the handle

mechanism and including a push button and handle locking member in a parked and locked configuration; Figure 3 is an end view at right angles to the view of Figure 2; Figure 4 is a view similar to Figure 2 but with the push button and handle locking member in a released configuration; Figure 5 is an enlarged view similar to Figure 2 but showing the movement of the locking member; Figure 6A is an enlarged view of a part section of the barrel of the push button taken on line 6A-6A in Figure 6G; Figure 6B is a section on line 6B-6B in Figure 6G; Figure 6C corresponds to Figure 6A; Figure 6D is a section on line 6D-6D in Figure 6G ; Figure 6E is an end view of the barrel; Figure 6F is a part sectional view of the barrel: Figure 6G is a section on line 6G-6G in Figure 6E; Figure 6H is a view in Direction'Z'in Figure 6G; Figure 61 is a side view in Direction'Y'in Figure 6D;

Figure 6J is a part sectional version of Figure 61; Figure 6K is a view in direction'X'in Figure 6J; Figure 7 is a sectional view of a second and preferred embodiment of the invention, showing in particular the cassette unit for mounting in the handle of the lockable handle mechanism; Figures 8 and 9 are sectional views through the barrel showing details of the barrel; Figures 10 and 11 are detail views of the push button showing its coupling with a lever member 770; and Figures 12A to 12E are sectional views through the cassette showing the handle release operation with gradual depression of the push button and more specifically in which: Figure 12A shows a locked position with the lever at rest and in contact with the handle locking member (which may alternatively be denoted a latch).

Figure 12B shows the button pressed to lmm movement such that the lever is tilting and in contact with the latch ; Figure 12C shows the button pressed to 2mm movement such that the lever tilt is increased and one end of the lever is in contact with the base of a housing cavity base such that the latch is about to rotate;

Figure 12D shows the button pressed to 2.5mm movement such that the lever has tilted in the opposite direction while in contact with the housing cavity base and the latch has retracted somewhat; and Figure 12E shows the button pressed to a maximum 2.6mm movement such that the lever is at rest on the housing base and the latch is fully engaged/depressed into the back plate.

Description of the Preferred Embodiment Referring now to the drawings, there is shown in Figure 1 a lockable handle mechanism 2 affixed to a window 4. The handle mechanism comprises a base 6, with a handle 7 rotatably mounted to the base 6 at a pivot 8, and including a manually depressible push button 10, with a key slot 11 for receiving a key for locking the push button. The push button is incorporated in a cassette unit 12, indicated in dotted lines, mounted within the handle. The cassette unit also includes a handle locking member 14, indicated in dotted lines, coupled to the push button 10 and arranged to engage in a recess 16 formed in the upper surface of base member 6. Although not shown, the handle pivot 8 is coupled to an espagnolette mechanism for closing and locking the window.

Alternatively a cockspur 18 may engage in a suitable window catch.

As shown in more detail in Figures 2-6, the cassette unit 12 has a housing 120.

The top of the push button has an outer elliptical plastics housing 20 in which an inner metal circular barrel 22 is rotatably mounted. Barrel 22 has a key slot 11 in which a key tang 24 is inserted. As shown in Figures 6D to 6J. internal projections 26 are provided, and require that the key tang be appropriately contoured so that it may be pushed past projections 26 into engagement with a differ projection 28, which comprises a slug mounted in a bore 30 in housing

20 resiliently biased by a spring (not shown) into key slot 23. Differ projection 28 serves both to retain barrel housing 22 within housing 20 and to lock the push button mechanism. Barrel housing 22 has at its lower end two diametrically opposing projections 34 extending from the barrel and offset relative to the key slot 23 (Figures 6B-6E).

As shown in the sectional views in Figure 6A, the barrel housing 22 is recessed as at 36 adjacent differ 28 so that in the normal inoperative position of the push button mechanism, differ 28 extends part way into key slot 23 to lock the barrel housing 22 to the housing 20. When the key tang is inserted into the slot, the differ projection 28 is pushed out of the slot area and permits the rotation of the barrel 22 so that the projection rides in the peripheral groove sections 38.39, groove section 39 being slightly deeper than groove section 38 for retention of differ 28.

In the normal inoperative position, the barrel projections 34 engage upon shoulders in the housing to prevent downward movement of the barrel housing. When the barrel housing is rotated, projections 34 are disengaged from the shoulders and downward movement of the barrel housing is permitted.

Thus the barrel housing 22 has two projections 34 at its lower end. shaped and spaced at 180 degrees radially apart. These function as locators between two matching 180 degree opposed static projections either side of the button. The barrel 22 can be rotated through 90 degrees total rotary movement between the static projections. At one extreme the barrel 22 is in the non button press position, at the other extreme the barrel 22 is in the button press position. The barrel 22 has a conventional key slot 11 with anti tamper blocks 26 within.

The differ projection 28 has a bullet shaped form and is hollow to contain a small compression spring, both being retained within the button housing 20 but able to move within a close fitting hole 30 radially displaced and perpendicular to the barrel external circular surface. Cut into the barrel circular surface is a radial groove 36 into which the spherical end of the differ is located and pre loaded by the action of the small compression spring. The radial groove 36,38,39 in the barrel 22 extends through 90 degrees at a varying radius about the barrel center line axis. At one end of the 90 degree groove is a deeper depression 36 into which the differ is located during the "locking"mode, the lower end of the depression penetrates into the barrel key tang slot 23, the key slot being narrower than the diameter of the differ, thus preventing the differ from"falling"further into the barrel key slot. In this position the differ prevents any rotation of the barrel and therefore the button cannot be depressed as the two projections 34 at the rear end of the barrel 22 are trapped. At the other end of the 90 degree groove is a shallow depression 39'into which the differ 28 is lightly located during the"unlocking/button" press mode, also the two projections at the rear of the barrel 22 are now in the untrapped position. In this position the differ 28 lightly retains the key tang 24 but can be"over-ridden"when the key tang 24 is withdrawn from the barrel 22 to depress the button 22. In any event the differ 28 locates and restrains the barrel 22 within the button housing 20 at all times.

The base of the barrel housing is arranged to engage locking member 50. The upper end of locking member 50 has two end pivots 52 which engage in vertical slots 54 formed in the cassette housing. Locking member 50 has a shaft portion 55 which extends from end pivots 52 to further pivots 56 which are arranged as shown in Figures 2 and 4 to engage in further recesses 58 in the cassette housing which are disposed at an upward angle to the horizontal, as shown in the drawings, of about 20 degrees. The lower operative part of

locking member 50 comprises a latch piece 60 whose lower edge is formed as a projection 62 which engages in recess 16 in base 6. A spring 64 is mounted in a compressed condition between a recess 66 in the upper surface of latch piece 60 and a recess 68 in the housing of the cassette.

Thus in operation in order to operate the door handle, the push button mechanism is first released, by inserting a key and rotating it, as described above, so that key tang 24 moves differ projection 28 out of the key slot and permits rotation of the barrel housing, with the projection riding in slots 36, 38, so that the projections 34 at the end of the barrel housing are disengaged from internal housing projections (or shoulders), thus permitting depression of the entire push button mechanism. The base 42 of the push button mechanism engages the upper end of locking member 50 which causes end pivots 52 to move downwardly in slots 54. Downward movement of end pivots 52 causes rotation of the locking member about further pivots 56, and additionally a sliding movement of further pivots 56 in slot 58 in a direction away from the push button mechanism and upwardly. This combined rotation and translational movement (due to the configuration of the pivots 52,56 and slots 54 58, particularly upwardly inclined slot 58) moves the latch piece 60 to the disengaged position as shown in Figure 4 in which lower projection 62 is clear of recess 16. permitting the handle to be rotated to operate the door or window opening mechanism. The positions of the pivots 52,56 and their configuration with the slots 54.58 provide a mechanical advantage so that movement of edge 62 is correspondingly greater than movement of the push button 10.

Although in this embodiment only one differ projection 28 is shown. two or more projections can be provided, disposed equi angular about the barrel housing.

Advantages of this first embodiment is that the housing for the handle is compact and contains only six components, four of which are formed in the cassette unit. The cassette unit, once assembled, may be later fitted into many different types of handle body.

In the preferred embodiment shown in Figures 7-12, similar parts to those of the first embodiment are denoted by the same reference numeral. A cassette unit 700 mounted within a handle (not shown, but similar to that of figure 1) has a housing 702. The cassette unit includes a push button 720 containing within it a key barrel 740. The push button is arranged to abut against a lever 770 for coupling movement of the push button member to a handle locking member 800 which is mounted in a recess 802 in base member 6 of the lockable handle mechanism.

Push button 720 is generally elliptical in cross section (Figure 8) and has an enlarged inner end 722 which is held within a first recess 704 within cassette unit 700. Enlarged inner end 722 contains a differ projection 726 spring biased to engage in a recess 742 within key barrel 740. Recess 742 may be seen more clearly in Figure 8 as communicating in a radial direction with a key slot 744, and in a circumferential direction with a peripheral slot 746. The inner end of key barrel 740 has opposing lateral wings 748 (Figure 9) for selectively engaging stops 708 in the lower surface 706 of recess 704 for controlling movement of the barrel. The arrangement of slots 744,746 and recess 742 is generally similar to that of the first embodiment as shown in Figure 6.

The lever 770 is as a simple lever with pivot stub shafts 772 representing the fulcrum point. The stub shafts 772 extend either side of the lever main body and into respective stub shaft slots 716 formed into the cassette housing. The

lever is located within the cassette assembly and is allowed two degrees of freedom-in line movement with the button press line movement but able to rotate about its stub shafts'centre line during in-line movement.

The lever ends sections 776,778 either side of the stub shaft 772 are of different length in the ratio 1). The shorter end 776 includes an offset end projection 780 and is situated inside a cavity 716 of the cassette housing.

The longer end 778 also includes an offset shape and is situated inside the lower cavity 718 of the cassette housing.

Two button projections 730 (Fig. 9) are placed slightly beyond the two barrel wings 748 positions in contact with and bearing onto the lever stub shafts 772.

The projection end is recessed as at 732 (Fig. 11) to wrap around almost half the diameter of its respective lever stub shaft within the width of the stub shaft slots 716. Each projection end 730 fits closely within its respective lever stub shaft slot for support and control during button press activation. The projections 730 are so shaped to provide a limit stop for the barrel wings at each end of their 90 degree respective rotary movement. When the button is pressed the two button projections 730 slide within their respective stub slots 716 in the cassette housings and they move the respective lever stub shafts 772 along the stub shaft slots.

A lever compression spring 780'is located with one end located into a lever spring recess 782 and the other end located into the cassette housing spring recess 718 During the locking mode the spring takes an in-line position between its end recesses. During the unlocking mode the spring remains partly compressed but with coils inline with its axis.

The handle locking member or latch 800 is housed within the base plate cavity 802 and secured at one end by stub shafts 804 being restrained but allowing the other end of the base latch to pivot outwards'wedge-like'from the backplate cavity 802 into a cassette housing lower cavity 718 and rest in contact with the lever 770 at 790. The pivoting end and underside of the base latch includes a blind hole 806 to support one end of a compression spring 808, the other end of which is restrained within the back plate.

In the locking mode the latch lower body 810 fits diagonally partly'wedge like'into the backplate cavity as the upper latch body 812 remains partly within the cassette recess 718, which is open at the underside of the handle.

In use, when a key tang 850 is entered into recess 744 of the barrel, it engages the spring loaded differ 726 at its spherical inner end projecting part way into the recess 744. As the key tang is pushed further into the barrel, the differ spherical end is raised up.

With the key tang 850 in position, the differ 726 is raised to permit the key to rotate the barrel 740 through 90 degrees. During barrel rotation the spherical end 728 of the differ is raised from the tang into the barrel peripheral groove 746 and thence along the full length of the barrel groove to permit full 90 degrees of barrel rotation. The action is more fully described with reference to Figure 6.

As the barrel rotates, wings 748 extending radially beyond the barrel diameter at the inner end of the barrel rotate correspondingly, through 90 degrees. The two button projections 730 are so placed at the inner barrel end so as to restrict the movement of the wings 748 through a maximum of 90 degrees. The push button may then be depressed.

Although captive within the cassette, the cassette design allows 3mm travel to the push button. Four lugs moulded at each corner of the button lower section limit this travel.

During the button press movement the lever moves through a controlled path dictated by the position and alignment of the lever stub shafts within respective lever stub shaft guide slots. The lever moves laterally, rotating and oscillating slightly as the projections make and break contact with inner surfaces of the upper and lower cavities of the cassette housings, as shown in Figures 12A to 12E.

The ratio of movement of the button to that of the latch is 1: 1.61 in favour of the latch 800. The button movement is 2.6mm whilst the designed latch movement is 4.83mm at the required position at its lowest point inside the base cavity 802.

In the unlocking mode (the button pressed). the latch 800 is depressed fully within the backplate cavity 802 to clear the lower cassette cavity 718 thus allowing the handle to be rotated to open sash position. When the button pressure is released. the base latch 800 reverts back to the locking attitude in the window open position.

The latch 800 body upper half 812 can be seen released above the backplate cavity in the sash open position. When the sash is returning to the frame closed position with the handle ready for rotation to the locking mode. the upper latch body 812 will ride under'the handle during rotation until it re- engages into the cassette cavity 718 at the locked mode position. As the upper latch main body 812 becomes fully engaged in the cassette cavity 718

the mating faces between these two components are in positive contact again in the locked position. The pivot end of the latch 814 acts as a limit for pivoting movement of the latch into the cassette cavity in the locking mode.

The latch 800 has a relatively large area of cross-section at the'shear line'816 and its shape and size is designed to absorb handle/backplate shearing loads during abnormal use acting between the walls of the grip body enveloping the cassette module assembly, and the backplate cavity 802. Transmission of shearing loads to the remainder of the cassette components are minimised in view of the close tolerances between the latch and parallel inside faces of the cassette housings within the handle cavity.

The attitude of the latch and its movement is designed to enable the overall height of the handle assembly to be constrained within 28mm maximum. The latch shape and size is governed by three factors: l. To keep a low profile within the available space below the button action.

2. To place the latch main body'shear section'as far away from the handle pivot as possible within the limits of the cassette length.

3. To ensure the shearing loads are not transmitted to other parts of the mechanism rather to retain and/or divert to the cassette housings within the handle close fitting cavity.