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.