WO1983001643A1

WO1983001643A1 - Security switch

Info

Publication number: WO1983001643A1
Application number: PCT/GB1982/000303
Authority: WO
Inventors: Industries Public Limited Company Lucas
Original assignee: Pickles, Kenneth; Little, Philip, Vernon
Priority date: 1981-10-28
Filing date: 1982-10-25
Publication date: 1983-05-11
Also published as: IT8249376A0; ES516926A0; ES8406134A1; FR2515240A1; IT1148631B

Abstract

A security locking switch for controlling electrical actuation of equipment such as enabling authorised use only of a telephone, comprising a housing (10) containing a plurality of gates (11) which are individually transversely movable across a passage (12) provided in the housing (10), an emitter (18) disposed at one end of said passage (12) and a detector (19) disposed at the other end of the passage, said emitter (18) being adapted to emit a signal which can be detected by said detector (19) and the gates (11) each having an aperture (13) which permits the passage therethrough of a signal emitted by the emitter (18), and a key, which may be a card adapted to be engaged with said gates for the purpose of setting them in positions in which their apertures (13) are aligned, the arrangement being such that in use, a signal emitted by the emitter (18) will only be received by the detector (19) to activate the latter when said gate apertures (13) have been aligned with each other, acutation of the detectors (19) being used to control said equipment. A key insertable into a conventional key barrel may be substituted for the key card.

Description

SECURITY SWITCH This invention relates to a security locking switch which is primarily but not exclusively intended for use in conjunction with a telephone in order to prevent unauthorised use of the telephone.

In one known form of such a telephone security lock for use with a telephone having an apertured, angularly movable dial plate the lock comprises a key-operable mechanism which can be releasably secured to the dial plate so as to project through one of the apertures therein and prevent turning of the dial plate to the maximum extent of its angular movement. Such known locks can however be prised off the associated dial plate or be otherwise removed so that unauthorised use of the telephone cannot then be prevented. Electronic locks or light activated locks have also been developed for various purposes but, apart from the above-mentioned key operated dial plate locks, no other simple effective telephone security locks have been developed. Such a security switch can be used in a variety of other applications, for example, a security switch can be used to control the use of electrical or electrically operated equipment such as radio equipment (military or civilian) or computers. A switch in accordance with the present invention may also be used to secure the doors or drawers of cabinets, the doors of safes, garages, vehicles, houses or factories, the operation of machine tools and, in other automotive applications, to lock gear boxes or hand brakes or to prevent use of batteries or ignition systems.

The object of the present invention is to provide a security locking switch in an improved and convenient form. In accordance with the invention there is provided a security locking switch for controlling actuation of associated equipment, said switch comprising a housing containing a plurality of gates which are individually transversely movable across a passage provided in the housing, an emitter disposed at one end of said passage and a detector which is disposed at the other end of the passage, said emitter being adapted to emit a signal which can be detected by said detector and said gates each having an aperture or signal permeable portion which permits the passage therethrough of a signal emitted by the emitter, there being also provided key means adapted to be engaged with said gates for the purpose of setting them in positions in which their apertures or portions are aligned, the arrangement being such that in use, a signal emitted by the emitter will only be received by the detector to activate the latter when said gate apertures or portions have been aligned with each other and with the emitter, such activation of the detector then being utilized to permit actuation of associated equipment.

Conveniently, the emitter is arranged to be electrically energised and there may be provided in its electrical circuit switch means which are arranged to be closed to energise the emitter only when the key means is inserted into the housing and into its operative position.

The emitter may also be connected to an indicator arranged to emit a visible signal (such as an LED) when the emitter itself is energised so as to indicate that the associated equipment is free to be used. The housing may also be provided, adjacent to the inner end of a slot through which, in use, the key means will be inserted, with a movable dust sealing member which will act to prevent or reduce the ingress of dust or dirt into the housing when the key means is not inserted therein but which will be pushed away from the slot by the key means (to permit entry thereof) as the latter is inserted into the slot.

A key may be in the form of a card which may be formed from moulded synthetic resin material. The card may have along one edge a series of portions of differing depth from a datum to engage the gates respectively.

The key may have provision thereon for locking in an operative position within the housing. Such provision may be a notch or aperture to engage with an associated formation on the housing. Alternatively the key may include a resilient tongue releasably engageable with a formation on the housing.

In a further alternative arrangement the key may engage in a pin or disc tumbler lock barrel, movement of the key being arranged to align the pins or discs in positions directly or indirectly to align the apertures or said portions.

The invention will now be more particularly described, with reference to the accompanying drawings, wherein:-

Figure 1 is a cross sectional elevation view of one example of a security locking switch constructed in accordance with the invention, the key means shown therein being broken away at its upper end; Figure 2 is a plan view of the switch seen in Figure 1 with the key means removed;

Figure 3 is a cross-sectional view on the line 3-3 of Figure 1;

Figure 4 is also a cross-sectional view on the line 3-3 of Figure 1 but with the key means removed; and

Figure 5 is a cross-sectional view on the line 5-5 of Figure 1.

Figure 6 is a cross-sectional elevation view of a security locking switch of an alternative form constructed in accordance with the invention.

Figure 7 is a view of a key card for use in the switch shown in Figure 6,

Figure 8 is a scrap view of the key card of Figure 7 shown engaged in the housing of the switch in Figure 6,

Figure 9 is a cross-sectional elevation view of a further alternative construction,

Figure 10 is a scrap view of the key card engaged in the housing in the construction of Figure 9.

Figure 10A is a view of an alternative form of key and

Figure 10B is a sectional view of this key

Figure 11 is a cross-sectional elevation view of a still further alternative form of security locking switch constructed in accordance with the invention, Figure 12 is a cross-sectional view on the line 12-12 in Figure 11,

Figure 13 is a cross-sectional elevation view of a further security locking switch constructed in accordance with the invention,

Figure 14 is a cross-sectional view on the line 14-14 in Figure 13, and

Figure 15 is a cross-sectional view on the line 15-15 in Figure 13.

Figure 15 is a cross-sectional elevation view of an alternative form of key arrangement, and

Figure 16A is a perspective view of the key used in the construction of Figure 16.

Referring now to Figures 1 to 5 of the drawings there is shown therein one example of a security locking switch suitable for use as a security device for a telephone comprising a housing 10 within which is mounted a plurality (in this case 4) gates 11 in the form of plungers which are individually transversely movable across a passage 12 formed in the housing. The gates may conveniently be formed as mouldings in a synthetic resin material and each gate is formed with an aperture 13 but as will be seen from Figure 1 the plurality of apertures 13 thus formed are located at different positions within the various gates. Each gate is spring loaded by means of a compression spring 14 arranged to urge the gate to a position in which the end of the gate opposite to the spring will engage a dust sealing member 15 (see Figure 4) which comprises a cylindrical roller which may be formed of a slightly resilient material and which in the position shown in Figure 4 will cover the inner end of a slot 16 through which in use key means in the form of a key card 17 (see Figures 1 and 2) can be inserted.

Also disposed within the housing is an emitter 18 which is arranged when energised to emit a signal. Conveniently said emitter 18 is arranged to be electrically energised and is arranged to emit radiation such as infra-red radiation. There is also provided a detector 19 which is disposed at the opposite end or side of said passage 12 with respect to the emitter 18 and which is arranged to receive a signal from the emitter only when all of said apertures 13 in the gates 11 are in alignment with each other and of course with the emitter. Conveniently, the emitter 18 and detector 19 are mounted on a printed circuit board 26 (see Figure .5) so that they project through apertures formed in the housing. Instead of each gate 11 being formed with an aperture 13, it may have an insert formed of a material which is transoarent or permeable to whatever form of signal will be emitted from the emitter 18. Each gate may have an integral portion forming the transparent or signal permeable window, the area of the window be surrounded or flanked by non transparent or signal permeable portions.

The construction in Figures 1 to 5 however does have four gates or plungers (although of course more may be used if required) and the apertures 13 shown therein have, in one typical example, diameters of 1.5 mms. and such a relatively small size of aperture obviously allows for a greater number of alternative aperture positions in a gate of given depth as compared with a construction in which the apertures are of greater diameter .

The lower edge of the key card 17 as seen in Figure 1 is shaped to suit the particular combination of the aperture layout in the associated gates 11 so that when said bottom edge of the key card engages the upper ends of the gates, the latter will be pushed downwardly against the forces exerted by the springs 14 to a greater or lesser degree in order that the individual apertures 13 can become aligned with each other. The lower edge of the key card therefore has a series of portions of differing depth from a datum which may be the opposite straight edge of the card or other line parallel, in use, to the plane containing the emitter and detector.

When the key card is first inserted into the slot 16 the lower edge of the card will engage the dust sealing element 15 and will push it laterally and downwardly along a channel which is downwardly inclined to the horizontal as indicated in Figure 3. Continued insertion of the key card 17 will then engage the upper ends of the gates and depress them against the spring loading 14 to a greater or lesser degree so as to bring the apertures 13 into alignment with each other and alignment with the emitter 18 is achieved by locating means comprising one or more apertures 20 formed in the key card and a corresponding number of projections 21 formed in the housing and projecting into the interior of the slot 16 part-way across the width thereof. Thus after the bottom of the key card 17 has been pushed past the projections 21 a position will be reached when said projections are aligned with the apertures 20 whereupon the key card can be rocked to effect engagement between the projections and the apertures so that the card can be retained in position as shown in Figure 1.

Furthermore in order to avoid the necessity of maintaining continuous energisation of the emitter 18 there may be provided a pair of resilient contacts 22 and 23 whereof contact 22 is connected to the emitter and contact 23 is connected for example to an electrical supply. There is also provided a member 24 which embraces the emitter 18 and which at its upper end is also adapted to be engaged by the lower edge of said key card 17. The lower end of said member 24 is provided with a projection 25 which, is arranged to engage the contact 22 so that as the key card is pushed downwardly, the member 24 will move downwardly from the inoperative upper position shown in Figure 5 to which it will have been moved by the contact 22, Figure 5 depicting the situation before the key card 17 is inserted. When however the key card has been inserted and has reached its operative position in which the aforesaid projections 21 are engaged with the apertures 20 then the contact 22 will have been pushed by the member 24 into engagement with the contact 23.

The emitter 18 will thus be energised for as long as the key card 17 remains in its operative position within the housing 10 but in another alternative the electrical circuitry may be arranged so that once the emitter 18 has been energised and the detector 19 has received a signal therefrom then the detector may be latched into this state for a predetermined time

Interval so that the key card 17 can then be removed if desired and the telephone or other equipment which is connected to the security switch could then be used until said time interval expires. In either case but particularly in the last mentioned arrangement there may also be provided means (such as an LED) for providing a signal to a potential user that the lock is in its activated state.

The detector 19 is of course arranged, on receiving a signal from the emitter 18, to permit use or operation of the equipment with which the security switch is associated and thus the detector can either be used to control the equipment directly or through the medium of a transistor, thyτistor or a relay when the security switch is to be used in conjunction with high powered machinery.

It may happen that an unauthorised person, without having the appropriate key card 17, may attempt to unlock a security switch as above described and initially it would then of course be necessary to energise the emitter 18 so as to provide a continuous signal before an attempt is made to move the gates 11 to their individually correct positions and in this case the unauthorised person might endeavour to push some instrument or tool into the housing 10 in order to bring the contacts 22 and 23 into engagement with each other. In order therefore to defeat such activities of an unauthorised user it is possible to incorporate in the circuitry a further detector which either locks all of the circuit concerned or alternatively activates an alarm if said contacts 22 and 23 are engaged for more than three times without accompanying alignment of the apertures 13.

The housing as shown in Figure 1 has projecting lugs 27 having apertures 28 into which screws can be inserted for mounting the housing in a desired position. In an alternative arrangement however the housing can be provided on its exterior with a plurality of barb-like plastic or other spring clips so that the housing would then be inserted into a mounting hole, thereby causing initial compression of such clips which would then expand into a retaining position behind the inner surface of such mounting hole when the housing had been pushed in to the appropriate depth.

It has of course to be understood that after the key card 17 has been removed from the housing by disengaging the apertures 20 and the co-acting projections 21 then the dust sealing member 15 will be pushed upwardly into its position in which it seals the slot by the upward pressure exerted by the gates 11 as they move under the influence of spring loading 14 into their upper positions.

Referring now to the alternative construction shown in Figures 6, 7 and 8 of the drawings there is a telephone security locking switch comprising a housing 30 which is adapted to be mounted in convenient position on the casing of a telephone with which the switch is to be used. Within said housing 30 is a plurality ( in this case 5) gates 31 which are individually transversely movable across a passage 32 formed in the housing. Each of said gates 31 is formed as a plunger with a solid top part and a cup shaped base with a joining stem. The solid top part in each case has an aperture 33 but as seen in Figure 6 the apertures 33 thus formed are located at different spaclngs from the flat tops of the respective gates. The gates may conveniently be formed as mouldings in a synthetic resin material and each gate is spring loaded by means of a compression spring 34 engaging in the cup shaped bases arranged so that the spring will urge the gate to a position in which the top of the gate opposice to the spring will engage the interior of the slotted top of the housing 30 as shown in Figure 6.

Also mounted within the housing 30 is a source of radiant energy 35 in the form of an infra-red emitter, and a detector 36, said emitter 35 and detector 36 being mounted at opposite ends of said passage 32. In the position shown in Figure 6 the various apertures 33 in the gates 31 are not aligned with each other so that infra-red radiation emitted in use from said emitter 35 cannot be received by the detector 36. However the switch as shown in the drawings would be supplied with a key 38 similar to that used with the switch shown in Figures 1 to 5 and shown in Figure 7. This key 38 is in the form of a card having a number of portions or castellations of differing depth from a datum, as described in relation to Figures 1 to 5. Such key card can be inserted into the interior of the housing through a slot 37 formed in the top of the housing, the portions or castellations on the key card are arranged to engage the upper ends of said gates 31 as the key card 38 is inserted into the slot 37 and the shape of such key card is thus complementary to the positions of the apertures 33 in the gates 31 so that when the key card 38 is fully inserted all the gates 31 will be pushed downwardly against their spring loading to a position in which the apertures 33 are aligned with each other. Infra-red radiation emitted from said emitter 35 can then pass through the aligned apertures 33 and be received by the detector 36. The infra-red emitter 35 may be replaced by a source of visible light and the detector 36 would then comprise a photo-sensitive device. The use of visible light possesses the advantage that some degree of illumination will be provided in the interior of the housing which can also be used to illuminate the key slot 37 to help the user in inserting the key card.

The key card 38 as shown in Figure 7 is provided with a handle portion 39 with an opening and an operative portion 40. In this example a shoulder 41 is formed between the handle portion 39 and operative portion 40 so that when the latter is inserted into the slot 37, the key card can be rocked into a position shown in Figure 8 in which said shoulder 41 engages behind a co-acting abutment 42 formed in the housing 30.

In use said detector may be linked to an electrical circuit which when used with a telephone will have the effect of "unlocking" the dialling mechanism of the associated telephone so that such dialling mechanism can then be used by the. authorised user having the aforesaid key card. Conveniently in this example the electrical circuitry can be arranged to provide for opening or unlocking of the dialling mechanism for so long as the key card remains inserted in the slot 17. Alternatively, the arrangement may be such that the dialling mechanism remains unlocked for a predetermined time after insertion of the key card, a delay of another predetermined time then occurring before the key card can again be used to unlock or open the telephone dialling mechanism.

Referring now to Figures 9 and 10 of the drawings there is shown a further alternative security locking switch which comprises a housing50 in which is mounted a plurality of gates 51. The gates are individually movable in parallel directions within the housing and each gate is normally biassed into an unward or inoperative position by means of a compression spring 52 these being of the form used in the switch of Figures 6, 7 and 8. Each gate also includes an aperture, insert or transparent portion 53, the various apertures being variously disposed as previously described. Thus with the gates in their upper or inoperative positions the apertures 53 will be disposed in non-aligned positions and can be aligned by insertion of a key card 54.

The security switch therefore also includes a key 54 of substantially constant thickness but which Is formed on the lower parts of two opposite sides of one face with chamfers 55. The upper end 56 of said housing 50 is formed with a slot which is so shaped that the key 54 can only be inserted into the slot in one orientation relative to the housing. The bottom edge of the key 54 engages the upper ends of said gates 51 as the key is pushed into the slot and the gates will be depressed by various distances as the key is inserted. Before key insertion the upper ends of said gates lying in a common horizontal plane when in their upper, inoperative positions. Figure 9 shows the gates in their position in which the apertures 53 are in alignment with each other. In this example a beam of light can pass through the array of gates from a fibre optic conduit 57 connected to a remote light source 58 and the beam of light emitted thereby can then be received in the end of another fibre optic conduit 59 which is connected to a remotely disposed detector 60. The latter will then be activated to complete an electrical circuit in order to control the operation of apparatus or equipment with which the security switch is to be used. The key 54 is also provided with a resilient integrally moulded tongue 61. The lower end of said tongue is formed with a laterally projecting lip 62 which is of downwardly tapered configuration in cross section. Furthermore said tongue is sufficiently resilient that when the key is pushed through the aforesaid slot in the top of the housing 56, the lower end of the tongue

61 will be pushed inwardly by engagement of the aforesaid lip 62 at one side of said slot. Once the lip has passed beneath said slot however the tongue will spring outwardly so that the upper part of said lip 62 will engage beneath the underside of said top 56 of the housing as seen in Figure 10. The various gates 51 will then be held in their operative positions against the forces exerted by the springs 52 so that the security switch will be activated for so long as the key remains in the housing.

When it is desired to remove the key the tongue is pushed inwardly by the user pressing a rib 63 which is also formed on one face of the tongue above said lip

62. Such pressure on said rib 63 will disengage the lip

62 from the underside of said top 56 of the housing and the key can then be withdrawn to permit the gates to return to their upper, inoperative positions.

In an alternative arrangement instead of moulding the aforesaid tongue 61 into the key, the tongue may be separately formed such as for example from resilient metal and can then be secured to the remainder of the key in any convenient manner as for example by being moulded into the key when the latter is formed or alternatively it can be connected thereto by means of rivets or screws or in any other convenient manner.

Figures 10A and 10B show an alternative form of key 111 which Is not in the form of a card but has a plastics moulded handle portion 112 and a metal insert 113 which has the operative portion formed on the end of it. The plastics handle portion has a tongue 114 accommodated in an opening in the metal insert 113 which is resilient and has a similar lip to that in the Figure 9 and 10 construction and is used to latch the key in operative position, in similar manner.

The alternative arrangement shown in Figures 11 and 12 comprises a housing 70 in which is mounted a barrel or cylinder 71 for angular movement in the housing.

Mounted within said barrel 71 is a plurality of plunger elements or wards known sometimes as discs in the form of plates 72 which are guided for slidable movement relative to the barrel in parallel directions transverse to the axis of said barrel. As shown in

Figure 12 each of said plunger elements 72 is formed at one end, namely the upper end as seen in Figure 12, with a laterally projecting wing 73 which is arranged to engage the upper end of a coiled compression spring 74 which is mounted in a recess formed in said barrel 71, the arrangement being such that said spring 74 is arranged to exert an upwardly directed force on said wing 73 and thereby on the associated plunger element 72.

Each of said plunger elements 72 is also formed with an aperture 75 which is conveniently of rectangular configuration, all of said apertures 75 being of the same length and width. The apertures are however arranged at various positions along the length of the respective elements or wards 72. The end of each element 72 opposite to the end having the aforesaid wing 73, namely the lower end as shown in Figure 12 is formed with a further aperture 76 which is of circular configuration and conveniεptly all of said apertures 76 are disposed at the same distance from the adjacent end of the associated plunger element.

A key 77 of known kind is provided, which can be inserted into a slot 78 formed in the barrel 71, so that on being inserted the key will enter into the aforesaid apertures 75 formed in the plunger elements 72. Initially, and before insertion of the key 77, the elements 72 will be aligned with a recess 79 formed in the interior surface of the housing 70 and the springs 74 will urge those ends of said elements 72 having the wings 73 into said recess 79 so as to prevent turning of the barrel 71 relative to the housing 70. On insertion of the key 77 into the slot 78 however said key will extend through the respective apertures 75 of the elements 72 so as to engage one end of each aperture. In known way, in accordance with the notches formed along one edge of said key, the elements 72 will be displaced, against the forces exerted by the springs 74 into positions in which one set of ends of the elements are withdrawn from the recess 79 whilst at the same time the opposite ends of said elements 72 will be moved so as to project into a further recess 80 which is formed in the interior surface of the housing 70 and which extends around said surface through an angle of approximately 90°. Furthermore with the key inserted into the barrel 71 to move the elements 72 as above described, all of said apertures 76 will now be in alignment with each other as seen in Figure 11. In an alternative arrangement the plunger elements are formed separately from gates and these are provided with the apertures 75 and are moved directly by the elements, which in turn are controlled by the key.

There is also provided in the housing a signal emitter 81 and a detector 82 which are disposed respectively on opposite sides of the array of plunger elements 72. Initially however when the key 77 is inserted into the slot 78 the ends of the elements 72 containing the apertures 76 will be adjacent to that end of the recess 80 indicated by reference numeral 83. On the other hand the emitter 81 and detector 82 are disposed in said recess 80 adjacent to that end opposite to the end 83 and accordingly the barrel 71 will have to be turned by the key 77 in order to bring the apertured ends of the elements 72 into the position shown in Figure 12 in order that the now aligned apertures 76 can be located between the emitter 81 and detector 82. Suitable means are provided for ensuring that the signal is not emitted by the emitter 81 until the elements 72 are in the position indicated in Figure 12 and in this position the aligned apertures 76 will permit the passage of such signal through the apertures in order to activate the detector 82 and such activation can then be used to control the operation of apparatus or equipment with which the security locking switch is associated. Retention of the barrel 71 within the housing 70 is conveniently accomplished by means of a spring loaded retaining plate 84 which engages with a further recess 85 formed in the interior surface of the housing 70.

Turning now to Figures 13, 14 and 15 there is shown a still further alternative embodiment comprising a housing 86 and a barrel 87 but said barrel is not rotatable relative to the housing. The barrel contains an array of plunger elements 88 with a rectangular aperture 89. Each plunger element also has a circular aperture 90 and associated with each element is a coil spring 91 (see Figure 15) which is disposed within a recess formed in the barrel 87 and which engages at one end a wing 92 formed on the associated plunger element. There is also provided a key 93 having a notched edge and which is adapted to be inserted into a slot formed in the barrel 87 so that said notched edge of the key can engage one end of each of the apertures 89 formed in the respective plunger elements. With the key 93 removed from the barrel 87 the aforesaid coil springs 91 will urge the plunger elements upwardly into positions in which the circular apertures 90 are not in alignment with each other but on insertion of the key 93 into the barrel, the array of plunger elements 88 will be displaced in parallel directions perpendicular to the length of the barrel 87 in order to bring the circular apertures 90 into axial alignment as seen in Figure 13.

There is also provided in the housing 86 means for emitting a signal which may conveniently comprise an emitter 94 of radiant energy said emitter having a lens 95 which can thus direct a beam of radiant energy towards another lens 96 forming part of a detector 97 disposed on the opposite side of the array of plunger elements to the emitter 94.A signal emitted by the emitter 94 can thus only reach the detector 97 when the apertures 90 in the array of plunger elements are aligned with each other, i.e. when the correct key 93 has been inserted into the barrel.

The emitter 94 will only emit a signal when it is switched on and such activation of the emitter is arranged to be effected by insertion of the key 93. To this end there is provided at. the inner end of the housing 86 (which is formed of an insulating material) a metallic contact plate 98 which is located between the adjacent end of said housing and the adjacent end of the barrel 87 which is formed of conductive material. A channel-shaped slot 99 seen in Figure 14, is formed in said contact plate 98 so as to form between the sides of such a slot a contact tongue 100 which can be engaged by the end of the key 93 when the latter is fully inserted into the barrel 87. The contact plate 98 is fed with current by feed conductor 101 which is led through a suitable aperture formed in the housing so that when the end of the key 93 touches the tongue 100 current will be transferred from said feed 101 to the contact plate 100 and then via the key 93 to the end one of the plunger elements 88 which is itself in contact with a part 102 of the conductive housing 87 and which has a conductive contact ring 103 which incorporates a conductor 104 which is connected to one leg 105 of the emitter. The other leg of the emitter is connected to earth by a lead 106 and so a full circuit through the emitter is established, thereby effecting energisation thereof. The contact plate 98 and the conductive ring 103 are themselves separated by an insulating ring 107 so that current can only be supplied to the emitter 94 when the key 93 touches the tongue 100.

Thus as previously explained, insertion of the key into the barrel 87 will align the apertures 90 and will also establish completion of an electrical circuit for supplying current to the emitter so that a signal can then pass through the aligned apertures 90 to be received by the detector 97.

Figure 16 shows a similar switch to that in Figure 6 but adapted for use with a generally cylindrical key 115 engaging in body 116 into a lateral passage therein. The key is shown in Figure 16A and has a handle end 117 and an operative end 118 which is generally cylindrical but has cut outs which engage the gates 119 which are otherwise similar to those in Figure 6. The key is pushed in laterally with the cut outs away from the gates 119 and to assist depression of the gates against their respective springs, the end of the key is chamfered at 120. When the key is fully in, it is rotated and takes up the position shown in Figure 16 in which the gates 119 are positioned to align their apertures with one another and with the emitter and detector.

Claims

1. In accordance with the invention there is provided a security locking switch for controlling actuation of associated equipment, comprising a housing containing a plurality of gates which are individually transversely movable across a passage provided in the housing, an emitter disposed at one end of said passage and a detector which is disposed at the other end of the passage, said emitter being adapted to emit a signal which can be detected by said detector and said gates each having an aperture or signal permeable portion which permits the passage therethrough of a signal emitted by the emitter, there being also provided key means adapted to be engaged with said gates for the purpose of setting them in positions in which their apertures or portions are aligned, the arrangement being such that in use, a signal emitted by the emitter will only be received by the detector to activate the latter when said gate apertures or portions have been aligned with each other and with the emitter, such activation of the detector then being utilized to permit actuation of associated equipment.

2. A security locking switch as claimed in claim 1 in which the emitter is arranged to be electrically energised.

3. A security locking switch as claimed in claim 2 including switch means arranged to be closed by insertion of the key means to its operative position, to energise the electrical circuit.

4.A security locking switch as claimed in any one of the preceding claims in which the emitter is arranged to emit infra red radiation.

5.A security locking switch as claimed in any one of claims 1 to 3 in which the emitter emits visible light.

6.A security locking switch as claimed in any one of claims 1 to 3 in which when the emitter is energised an indicator is also energised to indicate that the associated equipment is operational.

7. A security locking switch as claimed in any one of the preceding claims in which the key is in the form of a card having edge formations engageable with the respective gates to move them, upon key Insertion into the housing, by respective amounts to bring the apertures or said portions into alignment.

8.A security locking switch as claimed In claim 7 in which the key is arranged to enter the housing through a slot.

9. A security locking switch as claimed in claim 8 in which the key entry slot has a dust excluder member which is arranged to close the slot but which is moved to an inoperative position by insertion of a key.

10. A security locking switch as claimed in any one of the preceding claims wherein the key includes means for retaining it in operative position within the housing.

11. A security locking switch as claimed in claim 10 in which the means for retaining the key which is in the form of a card comprises respectively at least one hole and projection combination on the key and on the housing said hole and projection being interengaged when the key card is in an operative position within the housing.

12. A security locking switch as claimed in claim 10 in which the means for retaining the key which is in the form of a card includes shoulders formed respectively on the key card and on the housing, the shoulders being urged into engagement by spring means acting on the gates, but being manually manipulable to release the shoulder engagement to permit release of the key card from the housing

13. A security locking switch as claimed in claim 10 in which the means for retaining the key in. the housing includes a spring tongue on the key which is arranged to be releasably engaged with the housing upon insertion of the key.

14.A security locking switch as claimed in any one of the preceding claims in which the emitter and the detector are remote from respective positions in alignment with the apertures or portions, and signals are transmitted through fibre optics, having their respective ends aligned with the apertures or said portions.

15. A security locking switch as claimed in claim 1 in which the housing contains a barrel containing a plurality of plungers mounted for sliding movement in the barrel, the barrel having an entry slot for a key which, upon entry moves the plungers to respective positions in which the apertures or portions in the respective gates are correspondingly moved to alignment positions.

16. A security locking switch as claimed In claim 15 in which the apertures or said portions are formed in the plungers which thus serve as the gates.

17. A security locking switch as claimed in claim 15 in which the apertures or said portions are formed in gates which are formed separately from the plungers but which are moved by them respectively.

18. A security locking switch as claimed in any one of claims 15 to 17 in which the barrel is rotatable in the housing upon key insertion and such key insertion moves the plungers or some of them from positions in which such barrel rotation is prevented.

19. A security locking switch as claimed in any one of claims 15 to 18 wherein the barrel and housing and the key combine, upon key insertion, to make electrical concacts whereby the emitter can be energised.

20. A security locking switch as claimed in claim 19 wherein the correct key insertion operation completes an electrical circuit through the key.

21. A security locking switch as claimed in any one of the preceding claims wherein the key is generally cylindrical and is insertable into the housing through a lateral passage to engage the gates which project into the said lateral passage.

22.A security locking switch as claimed in claim 21 wherein the key is rotatable from an inoperative position when inserted to an operative position to displace the respective gates to their operative positions.

23. A security locking switch substantially as hereinbefore described with reference to and as shown in Figures 1 to 5 of the accompanying drawings.

24.A security locking switch substantially as hereinbefore described with reference to and as shown in Figures 6, 7 and 8 of the accompanying drawings.

25.A security locking switch substantially as hereinbefore described with reference to and as shown in Figures 9 and 10 of the accompanying drawings.

26. A security locking switch substantially as hereinbefore described with reference to and as shown in Figures 11 and 12 of the accompanying drawings.

27.A security locking switch substantially as hereinbefore described with reference to and as shown in Figures 13 and 15 of the accompanying drawings.