ACCESS CONTROL DEVICE

Abstract: A powered access control device which comprises a barrier (2) movably connected to a base (1), wherein drive means (13) are contained within the barrier, operative to move the barrier with respect to the base. A power supply (24) for the drive means may also be contained in the barrier and the drive means may be controlled remotely to make the device entirely self-contained.

Description: ACCESS CONTROL DEVICE This invention relates to a barrier, and particularly although not exclusively to a self-contained, remotely-controlled movable barrier which may be used to control access to an area. Access control posts (often known as " parking posts ") are well known devices which are used to secure the access to, or egress from, a specific area Typically they are used to control the use of a parking position, but may also be applied for security purposes to restrict entry to sites or to prevent the removal of a vehicle from them. Conventionally, an access control post is manually operated, and its use requires a driver to leave his vehicle, unlock the post, lower it to the ground, return to his vehicle, drive forward, and then get out again to raise the post and lock it. This process is inconvenient, and particularly so when (as is frequently the case) the lock on the post is located close to the ground. Because of this, posts are frequently left lowered by users, negating their purpose. In addition, there is a security risk in that while the driver is out of his car operating the post, the vehicle is open to snatch theft unless he has closed and locked it, adding to the inconvenience. Remotely-controlled power operated posts are known, but have gained little market acceptance because of their major disadvantages of (a) requiring an external power feed which increases the cost and complexity of installation and (b) having a bulky mechanism housing external to the barrier which is unsightly, prone to damage, and either reduces ground clearance or requires excavation below surface level. An existing power operated post comprises a barrier mounted onto a separate drive mechanism which moves the barrier. The provision of a separately housed drive mechanism increases both the bulk of the barrier arrangement and its cost. Where it is intended to install such an arrangement discretely this requires excavation to conceal the drive mechanism. Existing powered barriers rely on the barrier drive mechanism to retain the barrier in a desired position. In the event where a barrier is vandalised or struck with a vehicle the resulting shock is transmitted directly to the drive mechanism, possibly resulting in costly repairs. Where a powered barrier requires replacement the whole unit, barrier and drive mechanism must be replaced. According to the present invention there is provided a powered access control device comprising a base, a barrier movably connected to the base, and drive means disposed on the barrier operative to move the barrier with respect to the base. In a preferred embodiment the barrier comprises a metal chassis over which there is secured a cover which may carry insignia, reflective material or similar. The barrier is preferably pivotally connected to the base. The base preferably comprises a base plate. The drive means preferably comprises an electric motor and appropriate gearing, for example, a rotating worm gear which cooperates with a pinion. The drive means is preferably disposed within the barrier Power for the electric motor is preferably provided by means of an electric battery, also disposed on and more preferably within the barrier. Other suitable forms of power supply may however be employed, for example, mains electricity or solar power. Further, there is preferably provided a control means for controlling the operation of the drive means. Particularly, the control means enables the drive means to be operated to move the barrier between two predetermined positions with respect to the base. In a preferred embodiment the control means are effected by an electronic control means which is able to determine the position of the barrier relative to the base plate. The control means preferably determines position and movement of the barrier by monitoring the current drawn by an electric motor comprised in the drive means, although other embodiments are possible which employ photodetectors, microswitches, timers or any other suitable means As such, the control means are able to determine when the barrier reaches its limit of travel with respect to the base and also if, for any reason, movement of the barrier is restricted during operation Particularly, the control means are preferably arranged to distinguish between end of travel and collision with an obstruction, and in the event of the latter, to automatically reverse the barrier direction, for a short distance before stopping. In this instance provision may be made to stop or momentarily reverse the motion of the barrier to prevent damage to the barrier, drive means or obstruction. The barriers limit of travel may be set by the provision of suitable resilient end stops Further, a clutch assembly is preferably disposed with the drive means and any associated linkage, and is arranged to slip to prevent shocks being transmitted to the drive means as a result of the barrier being moved or encountering an obstruction. The control means preferably also includes means to enable the post to be controlled by a user. This is preferably effected by means of a radio receiver adapted to receive a predetermined coded radio signal from an associated transmitter. Other suitable means may however be employed, for example a remotely sited switch or other transmitter receiver combinations. Particularly, where the barrier is intended to be operable between an upright and horizontal position there may be provided a counterbalance spring operative to urge the barrier towards the upright position. Such a spring reduces the power requirement of the drive means for moving the barrier, between said positions. There is also preferably provided a locking means, arranged to lock the barrier into a desired position with respect to the base plate . In one configuration, for example, the base plate is mounted onto a road surface and the barrier is moved between a substantially horizontal and upright position . In this arrangement it is desirable that the barrier can be locked into the upright position. Preferably, the locking means is separate to the drive means and is controlled by an electric motor, which in turn is controlled by the control means . Provision may also be made to allow manual operation of the locking means, for example through a conventional lock and key arrangement. To protect the device from accidental damage by, for example, motor vehicles when parking, the base of the barrier may be mounted onto a road surface using resilient mountings, for example, by disposing springs along the shaft of bolts used to secure the base plate in position between the base and road surface. In one embodiment there is provided a self-contained access control post which contains within the post an electrically-powered mechanism and its battery power supply, and is controlled from a remote control unit transmitting a coded radio signal. The control unit may be mounted in a vehicle or hand held, and includes electronic circuitry controlling a radio transmitter which sends a code when a control (e.g. a push-button) on the control unit is operated. The code transmitted may be unique to one post, or may be a master-code relating to a group of posts, permitting management over-ride (e.g. in car parks) A radio receiver in the post monitors continuously for transmissions, and on receipt of a valid code operates the mechanism inside the post to either raise or lower it. Irrespective of the initial position of the post, a single press of the button on the control unit will cause the post to operate to the opposite limit of travel. When the post is in the upright position, an internal locking mechanism which operates automatically as part of the control cycle secures it firmly vertical. Power for operation of the post is provided by internal primary batteries. Through the use of low-power radio receiving and monitoring circuits, current drain from the batteries during "waiting " mode is minimised so that a life of at least one year between battery changes is obtained in normal use. A counterbalancing spring is employed to urge the post to an upright position this reduces the power requirements of the mechanism employed to raise the post, this further enhances battery life. In the event of a failure of remote operation of the post (for example because of discharged batteries in the post or the transmitter, or through malfunction) , provision is made for manual operation by the use of a key operating in a lock at the top of the post. Opening the lock allows access to a release control for the vertical locking mechanism . Once this is released, the key may be removed and the post lowered without the need for the user to bend down to ground level. A slipping clutch arrangement makes manual movement of the post possible without damage to the internal mechanism . The slipping clutch also reduces the risk of damage through vandalism, and this is further enhanced by the provision of resilient stops for the post in the vertical position. The complete post is similar in dimensions to a conventional manual post, and its ground fixing plate is of comparable size and ease of fixing. If it is required to remove the post (for example to repair it), the complete moving portion including all the mechanism may be simply detached, leaving the base plate in situ. The present invention affords a number of advantages over existing powered access control devices and parking posts. As the drive means are housed within the barrier itself this renders a separate housing unnecessary, improving the appearance, ease of installation, and also reducing the cost of the barrier. The provision of a counterbalancing spring considerably reduces the power requirement to raise and lower the post, this enables a battery powered drive means to be used, in contrast to existing mains electricity powered posts. Where battery operation is employed this makes the barrier entirely self contained, the installation of the barrier is therefore more convenient and less costly than for conventional powered barriers. Where a clutch is provided in the drive mechanism for the barrier this enables the barrier to be moved by hand in the event of failure of the drive means. Provision of a locking means, separate to the drive means enables a locking means of considerable strength to be provided, whilst enabling the drive means to be produced as economically as possible. The use of an electronic control means which is able to monitor the current drawn by the drive means improves over barriers which employ microswitches or other means to detect the position of the barrier. An entirely electronic means reduces the number of separate components required this, both reduces cost and the likelihood of component failure. Also, an electronic control can incorporate a self reversing feature, when the barrier encounters an unexpected obstruction. In order that the invention may be more clearly understood an embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which:- Figure 1 shows a vertical cross section through the front elevation of a parking control post, with some details omitted for clarity; Figure 2 shows a vertical cross section through a side elevation of a parking post similar to that illustrated in Figure 1 ; Figure 3 shows an exploded view of part of a parking post, showing in detail the mounting of the shaft to the base plate; Figure 4 shows in more detail the shaft and clutch arrangement of a parking post; and Figure 5 is a circuit diagram for the control circuitry of a parking post. Referring to Figures 1 to 4, the post comprises essentially of two parts, a fixed base plate 1 which is secured to the ground and a movable chassis 2 which is in effect hinged to the base plate and contains the mechanism and battery power supply. Base plate 1 is of rigid construction and has a flat base which can be secured to holes drilled into a suitably strong ground structure by conventional anchor bolts 31 through the fixing holes 3, with no need for excavation. Secured to the base plate 1 are two side members 8 each having an accurately machined vertical slot 4 which is open at the top end. The post body is mounted to the base plate by sliding the milled tongues 5 on the ends of the shaft 6 into the slots 4. The shaft is secured in position by retaining plates 7 which incorporate inverted slots 29 for tongues 5 and are fixed to the side members 8, by rivets 38. The ends of shaft 6 and the fixings for plates 7 are concealed and protected by covers 37. Fixings 38 for retaining plates 7 may be designed to be of a strength which will shear under impact of a vehicle with the post. Once fixings 38 have sheared, tongues 5 are able to rise up slots 4, allowing the complete post assembly to disengage from base plate 1 without significant damage to post or base plate. The movable chassis 2 is provided with an elongated cover 28, forming the body of the post. The cover 28 may incorporate various internal and external details formed by extrusion or other means and required for decorative or assembly purposes, including for example external vertical slots to contain light reflector strips and internal vertical slots to locate the battery carrier 24 and allow it to slide upwards for battery replacement The lower of end of cover 28 is fixed by rivets or security screws to chassis 2, and its upper end is closed by a formed or moulded cap 25 incorporating locking means 34 for obtaining emergency and service access Shaft 6 forms the axis around which the post rotates, and remains stationary in the base plate because it is restrained by the close fit of the tongues 5 in the slots 4 A pinion 9 is located on the shaft, approximately centrally between side plates 8, but is not directly fixed to the shaft Under normal operation, however, the pinion is unable to rotate relative to the shaft 6 because of a friction clutch mechanism 10 consisting of fixed collars 35, moving collar 23, and compression spring 1 8 The fixed collars are secured to shaft 6 by roll-pins 41 Moving collar 23 and fixed collar 35 have friction surfaces 1 5 in contact with the faces of pinion 9 In operation, spring 1 8 forces collar 23 against pinion 9 Although collar 23 is able to move along the shaft to a small extent, it is keyed to the shaft by roll-pin 36 in an elongated hole and so is unable to rotate relative to the shaft Pinion 9 (which is otherwise free to rotate) is thus effectively locked to shaft 6 unless the applied torque is sufficiently higher than the normal operating torque to overcome the fπctional force between pinion 9 and friction surfaces 1 5 The design parameters of friction clutch 10 are so determined that under normal operation or upon contact with an end stop or external object the clutch does not slip, and pinion 9 is effectively locked to shaft 6 Gear set 1 1 co-operates with the pinion 9 so that in normal operation, when movement of the post is required, rotation of the gear set 1 1 causes chassis 2 to rotate around fixed shaft 6, the direction of post movement (raise or lower) being determined by the sense of rotation of the worm gear. Gear 1 1 is mounted on the output shaft of a gear-box 1 2 which steps down the output from a d.c . motor 1 3. Motor 1 3 is firmly secured to movable chassis 2. Counterbalance springs 22 attached between movable chassis 2 and lugs 43 secured to fixed collars 35 are so calculated as to approximately compensate for the turning moment generated by the weight of the post throughout its range of movement, thus equalising load on the motor over the range of travel and between raising and lowering. When the moving post reaches end of travel in either direction, it comes into contact with one of the resilient end-stops 1 4, causing the driver motor to stall. The substantial increase in the current drawn by the motor at stall is sensed by the control circuitry on circuit assembly 21 in order to determine end of travel and so to discontinue drive current to the motor. Sensing end of travel in this way eliminates the need for sensors such as micro-switches or photo-cells, any of which would be prone to unreliability in the harsh road-level operating environment. This current-sensing process also provides a safety over-ride in the event that the moving post comes into contact with an obstruction before it reaches normal end of travel, such as the face or underside of a vehicle, or a foreign body or irregularity on the road surface. End stop 14 may be made resilient (for example by the use of a sandwich or metal and rubber or by construction as a spring plate) to enhance the resistance of the structure to accidental damage or vandalism, to provide a softer end of travel for the moving post, and to take up manufacturing tolerances in the mechanism. End stop 1 4 may also be designed to collapse under severe overload (for example from vehicle impact), absorbing mechanical energy and reducing damage to the post. Means are provided to secure the post in the upright position once it has reached the vertical end stop, by propelling a fork 1 6 downwards so that its two ends 17 located behind the end stop and firmly wedge the post. Movement of the fork is achieved by the combination of spring 39 and cam 1 9, which is rotated by a d.c . motor and gearbox 20. Rotation of cam 20 from the raised position allows spring 19 to propel fork 1 6 downwards into the locked position. Reversal of motor 20 reverses the direction of rotation of the cam and raises the fork to unlock the post. End travel of the fork may be detected in a similar way to that used for detecting end travel of the post, by allowing the cam to strike an end stop and identifying the rise in motor current which accompanies the steep increase in load . Alternatively, end of travel of locking fork 1 6 may be determined by microswitches or other sensing means, such more conventional methods being more suited to controlling travel of the internally-contained fork than for travel of the post itself. No locking mechanism is provided for the post when it has been lowered to the horizontal, because (a) the end of travel may be variable due to uneven ground, and (b) it is more prone to vandal damage than in the upright position, since a lever can be inserted between the ground and the lowered post and considerable force exerted . Leaving the lowered post unlocked means that it can be pulled up by hand against the slipping clutch without damage to the mechanism and (since if unenergised it will not lock in the upright position) may then be pushed down again without damage. The electronic circuitry incorporated in assembly 21 controls and sequences the various phases of operation . Starting with the post in the upright position, once a valid signal has been received from the remote control, power is applied to the locking motor 20 in the correct polarity to withdraw locking fork 1 6. When end of travel of the fork is detected, power is removed from motor 20 and applied to motor 13 in the correct polarity to lower the post until end of travel of the post is detected. This sequence of events is reversed to raise the post. In alternative embodiments, electronic timers and/or tilt switches may be used to identify that the moving post has stalled before its normal end of travel (for example by striking an obstruction such as the rear or underside of a vehicle) . The control circuitry may be designed to automatically reverse the direction of travel in such an event, in order to move the post away from the obstruction The tilt switches may in addition be used to indicate to the control circuitry any change in the orientation of the post (for example, by manual operation) since it was last operated under power. Power for all post operations is obtained from a set of standard primary batteries 24 contained in the upper part of the post. Current drain from the batteries is caused two loads (a) standby power to the radio receiver (b) drive power to the motors and control circuits. Although (b) represents a heavy load it is only required in short occasional bursts and the greater drain on the battery over its operating life is (a), which is powered continuously. This drain is minimised by the use of low power radio receivers to obtain an operating life of over one year in normal usage from a single set of batteries. In an alternative power supply arrangement, photocells may be used to provide the continuous standby power for the radio receiver, substantially extending battery life. The photocells may be mounted in external slots in the post cover 28, which slots may also be used to mount strips of reflective material for safety purposes. As an alternative to primary batteries, rechargeable cells (e.g . NiCad type) may be provided, which may be charged by photocells or via a charging socket by connection to e.g. a car cigar lighter socket or other suitable source of d.c power when required. Indicator lights 30 are provided in the post in positions easily visible to the user, to provide information on post operation including an indication that the batteries are becoming discharged and need to be replaced. Alternatively an audible warning may be given by a sounder. To minimise battery drain such indicating devices are activates only when the post is being operated. A hand-operated wireless remote control is provided for the user. Operation of a button on the control gives out a radio signal in one of the licence-exempt bands reserved for such applications. Each post is provided with its own unique code to prevent spurious operation of any neighbouring posts. One operation of the button causes the post to operate through one cycle of operation, either down-to-up or up-to-down, depending on the start position. In the event that the post mechanism fails to operate for any reason, means is provided for the user to lower the post manually if it is locked in the upright position . Having used a key in lock 34 to release cap 25 from the post, link 32 can be pulled to raise locking fork 1 6 against the tension of spring 39 from engagement with end stop 14. The slipping clutch 1 0 then permits the post to be lowered. After the post has been lowered a short distance the fork will no longer engage so link 32 can be released and the cap replaced and locked before the post is pushed all the way to the ground. In an alternative arrangement, the link 32 may be attached to a cam on lock 34 so that the action of turning the key pulls on the link and raises the locking fork 1 6. This enables the post to be manually operated without removing the post cap 25. Removal of cap 25 also permits battery replacement by enabling access to the battery set and holder 24, which may be manually raised to the top of the post. It should be apparent to one skilled in the art that, although the remote control means described above employs a radio frequency link in a specific frequency band, that link can readily be provided in another electro-magnetic frequency band or by other radiative means including an acoustic system. Referring to Figure 5 there is illustrated a circuit diagram of the control circuitry employed to operate the motors of the parking post. The circuit is based around a programmable microprocessor 40, a suitable processor is device type PICI6C71 . The microprocessor is programmed to operate the drive motor and lock motor of the post in response to a trigger signal and also in relation to the current drawn by the drive motor. A trigger signal, to activate the circuit is applied to the microprocessor 40 by means of the trigger connection 41 . The microprocessor 40 is arranged to output signals to operate the drive and lock motors. These signals are fed to interlock circuitry 42, which comprises a number of logic gates and is arranged to ensure that only appropriate signals are applied to the motors, for instance to prevent the circuit from attempting to drive a motor in two directions simultaneously. The output from the interlock circuitry 42 is applied to a level shifter 43 (device type 4504) which enables the voltage of the motor drive signal to be set at an appropriate level to run the motors. The level shifter 43 outputs a signal which is fed to the motors via diodes 44 which are arranged to protect the circuit from any back emf. The drive motor is connected to terminals 45,46, the lock motor is connected to terminal 47. The current drawn by the motors is monitored by the potential divider 45, amplifier 49 and associated components. The amplifier 49 outputs a signal corresponding to the current supplied to the motors, this signal is transmitted to the microprocessor 40. The circuit also provides a number of other functions. Diodes 50 and resistors 51 form a battery level monitor, information as to the electrical condition of the batteries is transmitted to the microprocessor. Speaker 52 and associated components 53 enables an audible warning signal to be generated to indicate, for example, that the barrier is moving . Light emitting diode 54 and associated components enable a visual signal to be produced, for example, to indicate the battery condition. Components 55, form a conventional voltage regulator to supply the circuit with a stable power supply. Crystal 56 and associated components provide a clock signal to drive the microprocessor 40. The trigger signal is provided by a conventional receiver, not illustrated, which is adapted to produce a signal in response to receipt of a radio, or other signal, produced by an associated conventional transmitter. The microprocessor is programmed to allow the post to perform the functions described above. For example, when the post is in the upright locked position, upon receipt of a signal at the trigger connection 41 the microprocessor 40 operates the lock motor to unlock the post, followed by the drive motor to move the post to the horizontal position. When the post reaches the limit of travel the increase in the current drawn by the drive motor causes the microprocessor to cease supplying the power to the drive motor. Upon receipt of a further trigger signal the drive motor is activated to raise the post to the upright position, when the post is raised the lock motor is activated to lock the post in position. By comparing the time taken before the drive motor stalls, compared with the expected time taken to raise or lower the post the microprocessor can distinguish between the post making contact with an end stop or an unexpected obstruction. Although the design and operation of the access control device have been described above with specific reference to a battery-powered ground-mounted parking post, it will be evident to one skilled in the art that the invention may readily be implemented in other formats to provide remotely-controlled moving barriers differently formed and otherwise powered and mounted, and used for controlling access of personnel, animals or other moving objects than vehicles . The invention may also be applied with ease to temporary installations, where its self-contained, self powered nature makes it particularly suitable. Since these and certain other changes may be made without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted in an illustrative and not a limiting sense.

Claims: CLAIMS 1 . A powered access control device comprising a base, a barrier movably connected to the base, and drive means disposed on the barrier, operative to move the barrier with respect to the base. 2. A powered access control device according to claim 1 , wherein said drive means comprises an electric motor. 3. A powered access control device according to claim 1 or 2, wherein provision is made for a power supply for said drive means to be also contained within the barrier. 4. A powered access control device according to any preceding claim, wherein control means are provided for controlling said drive means. 5. A powered access control device according to claim 4, wherein said control means comprises an electronic control means. 6. A powered access control device according to claim 4 or 5, wherein said control means enables the drive means to be operated remotely. 7. A powered access control device according to claim 6, wherein control means includes a means for transmitting and a means for receiving radiation . 8. A powered access control device according to any preceding claim, wherein said drive means incorporates a clutch arranged to slip at a predetermined load. 9. A powered access control device according to any preceding claim, wherein counterbalance means are disposed on the barrier. 10. A powered access control device according to any preceding claim in which there is also provided a locking means, to enable the barrier to be locked into a desired position with respect to the base. 1 1 . A powered access control device according to claim 10, when appendant directly or indirectly to claim 4, wherein said locking means is controlled by said control means. 1 2. A powered access control device according to claim 1 1 , wherein there is also provided a means for manually engaging and releasing said locking means. 1 3. A powered access control device according to any of claim 4, or to any of claims 5 to 1 2 when appendant directly or indirectly to claim 4, wherein said control means monitors the current drawn by said drive means. 1 4. A powered access control device according to claim 1 3, wherein the monitoring of the current is relative, not absolute. 1 5. A powered access control device according to claim 4, or to any of claims 5 to 1 2 when appendant directly or indirectly to claim 4, wherein said control means is arranged to distinguish between the end of travel of the barrier and collision of the barrier with an obstruction, and in the event of the latter to reverse the direction of the barrier before stopping. 16. A powered access control device according to any preceding claim, wherein the drive means incorporates a rotating worm gear co-operating with a fixed pinion. 1 7. A powered access control device according to any preceding claim, wherein resilient end stops are provided at one or more limits of travel of the barrier. 1 8. A powered access control device according to claim 7 or any of claims 8 to 1 7 when appendant directly or indirectly to claim 7, wherein the radiation forms a remote control signal which is encoded so that only a relevant barrier responds. 1 9. A powered access control device according to claim 1 8, wherein master encoding means is provided to enable a selected group of barriers to be controlled simultaneously. 20. A powered access control device according to any preceding claim wherein one or more photoelectric cells are provided for the supply of power.

Inventors: BOWLES ALEXANDER GARY, BOWLES, ALEXANDER, GARY
Applicants: BOWLES ALEXANDER GARY, BOWLES, ALEXANDER, GARY
Application year: 1997
Main classification: E01F13
IPC codes: E01F13