GB2177277A - Safety devices - Google Patents

Abstract

Safety of a vehicle 15 reversing towards a platform 17 is improved by a curtain 19 e.g. of ultrasound or microwave radiation associated with a sensor 18 including a Doppler effect sensor such that interruption in the beam by movement transverse to the beam energizes an audible and/or visible warning device 29, 30 controlled by the sensor 18. The warning devices may also be energized by interruption in the beam caused by a vehicle moving forwards. Movement of vehicles side by side may be sensed. <IMAGE>

Description

SPECIFICATION Safety devices This invention relates to safety devices.

According to this invention a safety device comprises means for producing a sensing beam, means for sensing interruption in the beam produced by movement of a body transverse to the beam, and means for producing a warning signal on interruption in the beam.

The beam may extend in two dimensions and may have generally planar faces.

The sensing means may be responsive to a change in a reflected beam corresponding to a change from a datum caused by the interruption.

The sensing means may be responsive to a Doppler effect.

The warning signal may be produced a predetermined time after the beam is interrupted.

The sensing means may be responsive to interruption produced by movement of the body in either of two opposed directions.

The sensing means may sense removal of the interruption, and means for producing a warning signal on said removal. The warning signal may be produced a predetermined time after said removal.

The sensing means may comprise a device for producing electric pulses, a counter for counting the pulses, and means for energizing the means for producing the warning signal after a predetermined number of pulses have been counted.

The beam may be microwave electromagnetic radiation.

The beam may be ultrasound.

The beam may be emitted through a beam shaping element.

The shaping element may have generally flat parallel side walls leading to a rectangular output mouth.

The invention also includes such a device installed in a loading bay.

The invention includes a safety device however defined.

The invention may be performed in various ways and one specific embodiment with possible modifications will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a side view of a loading bay; Fig. 2 is a plan view; Fig. 3 is an electrical circuit; and Fig. 4A, B, C are front, side and plan views of a sensor.

The principal purpose of the device is to give a pre-set, timed, audible/visible warning to the driver of a vehicle which is approaching an obstacle (such as a loading bay, wall or other obstruction) that the vehicle has arrived within such close proximity of the obstruction, that, from that point, greater care must be employed when manoeuvring the vehicle (or similar) to a closer situation in respect to the obstacle.

The safety device is shown in Fig. 1 in association with a loading/unloading bay 11 including a platform 12, a warehouse wall 13 and a bay roof 14. A vehicle 15 would normally reverse towards the platform and the device is intended to assist in preventing the rear 16 of the vehicle smashing into the front 17 of the platform. The device includes a sensor 18 which is shown mounted on the roof 14 so as to produce a curtain beam 19 of electromagnetic radiation which has generally planar falls and has a vertical component and is spaced a distance in front of the platform edge 17. The curtain 19 is preferably inclined at not more than 45" to the vertical. The curtain has a certain width in a direction towards and away from the platform and may be somewhat wedgeshaped.As the vehicle reverses, it crosses or interrupts a part of the curtain and this causes a change in the frequency of the signal reflected to the sensor and this change is sensed by sensor 18 which is responsive to the Doppler effect produced by the change in frequency. The sensor 18 produces an output signal on line 20 (Fig. 2) to each of two electronic memorizs or stores 21, 22, comprising counters, which can produce output signals on respective lines 23, 24 to input to a trigger unit 25 which produces an output signal on line 26 to an automatic reset timer 27 which produces an output signal on line 28 to audible and/or visible warning devices 29, 30. The various electrical components are supplied from a power bus 31 from source 32. The sensor 18 includes a microwave head having an electrical output signal dependent on the frequency of the received reflected signal.A circuit is responsive to a change in frequency from a base reflected frequency corresponding to an uninterrupted curtain and a DC output voltage of a magnitude related to the change is compared with datum values in the memories. One memory is responsive to values less than the datum, the other to values greater than the datum. The movement of the place at which the beam is reflected from, for example, the ground active as a datum to, for example, a vehicle roof is perceived by the head as a Doppler effect or change in frequency.

There may be more than one of the devices 29, 30 and they may be located as desired e.g. in the roof, the warehouse wall or the ground 33, as convenient and desirable in any particular case.

The sensor 18 is a Doppler microwave device which emits a curtain of electromagnetic waves which normally are reflected as a datum from ground 33 back to the sensor 18 where they are detected.

When the vehicle interrupts the curtain, the time taken for the reflected radiation to reach the sensor is reduced and this produces a Doppler effect which is detected by the sensor to produce a series of pulses in output line 20 and when the number of pulses has reached a predetermined, adjustable, threshold, an output signal is produced on line to operate the trigger 25 to start the warning devices 29, 30. After a predetermined, adjustable, time the re-set unit 27 stops or deenergizes the warning devices 29, 30.

If the vehicle partly breaches the curtain but does not penetrate completely and then stops, a warning is energized. If the vehicle now moves further back thus further interrupting the beam a further warning is energized.

Similarly, when the vehicle moves forwards, thus restoring the curtain, this is sensed by sensor 18 and pulses, different from the previous pulses, are sent on line 20 to the memories. One memory responds to the pulses indicating approach of the vehicle to the platform, the other memory responds to the pulses indicating forward movement of the vehicle. The memories may be selectively switched into the circuit so that the device may respond only to reversing of vehicles, or only to forward movement of the vehicles, or to both reverse and forward movement of the vehicles which interferes with or alters the curtain 19.

The sensor will respond to movements of any one of a number of vehicles side by side so that the device can be used with a loading platform handling a plurality of vehicles simultaneously.

The sensor 18 Fig. 3 includes a flattened output horn 40 which has diverging flat sides 41, a rectangular mouth 42. The microwaves are produced by an element indicated at 43.

The horn 40 is mounted for pan and swivel adjustment i.e. side to side and fore-and-aft in relation to wall 13.

The device described may be pre-adjusted in such a way that it presents the effect of an invisible sensing curtain 19 which reacts to the approach of any solid mass in that a series of impulses are recorded into an electronic memory and when these reach an, adjustable, pre-set level then the trigger unit activates a timer module, with auto-reset facility, in such a way that an audible/visible warning is given for any pre-set time period. This audible/visible warning portion of the equipment may be mounted in any position most suitable to warn the driver of an approaching vehicle (for instance). The devices sensing properties are derived from the use of a Doppler microwave sensor 43 housed in a horn-like housing 40 producing a roughly fan-shaped curtain-like sensing area 19.The pre-set triggering device will ensure that adjustably repeated intrusions into the curtain area are detected.

The memories are arranged in such a way that either may be switched in or out so that it may be arranged that movements either towards or away from the sensing area are detected or, if required, in both directions.

Transverse movements of mass along the plane of the sensor "curtain" either from left to right, or the reverse, will almost invariably not be detected.

The target area of the sensing "curtain" may readily be adjusted in relation to the relative positions of the vehicle (or mass) so as to pre-designate that distance from the obstruction at which the audible/visible warning is given. The sensitivity and target travel threshold distance to warning are adjustable as is either memory decay time.

The sensitive "curtain" effect is produced by compressing the normally oval sensitive area of a Doppler microwave device by means of a special "horn" shaped funnel housing.

The effective width of sensing "curtain" in front of a loading bay or other obstruction is governed by the height and position in which the sensing device is mounted and the setting of the various controls embodied thus a number of vehicles presenting themselves side by side, in any order, if within the designated "curtain" will be detected if moving either towards or away from the "curtain", as selected, or in both directions if required but almost invariably not in any case, if moving along the plane of the "curtain" in either transverse direction.

The detection device may itself be mounted on the housing for all or some of the electrical/electronic circuitry which may in turn be mounted with or without the aid of a bracket from wall, roof, ceiling or convenient and appropriate fixing place. The sensor head itself is mounted in such a way that it may be adjusted laterally or transversely with regard to its mounting position.

The audible warning device may consist of, for example, a Klaxon horn or bell and the visible warning device may consist of, for example, a xenon beacon flasher or other flashing light.

The device can be used to detect movement of a mass other than vehicles.

In an example the device may be particularly effective with vehicles moving at from 10 to 20 mph.

In a modification the head 43 is arranged to produce an ultrasonic beam.

Claims (17)

1. A safety device comprising means for producing a sensing beam, means for sensing interruption in the beam produced by movement of a body transverse to the beam, and means for producing a warning signal on interruption in the beam.

2. A safety device as claimed in claim 1, in which the beam extends in two dimensions.

3. A safety device as claimed in claim 2, in which the beam has generally planar faces.

4. A safety device as claimed in any preceding claim, in which the sensing means is responsive to a change in a reflected beam, the change being from a datum and caused by the interruption.

5. A safety device as claimed in any preceding claim, in which the sensing means is responsive to a Doppler effect.

6. A safety device as claimed in any preceding claim, in which the warning signal is produced a predetermined time after the beam is interrupted.

7. A safety device as claimed in any preceding claim, in which said sensing means is responsive to interruption produced by movement of the body in either of two opposed directions.

8. A safety device as claimed in any preceding claim, in which the sensing means senses removal of the interruption, and means for producing a warning signal on said removal.

9. A safety device as claimed in claim 8, in which the warning signal is produced a predetermined time after said removal.

10. A safety device as claimed in any preceding claim, in which the sensing means comprises a device for producing electric pulses, a counter for counting the pulses, and means for energizing the means for producing the warning signal after a predetermined number of pulses have been counted.

11. A safety device as claimed in any preceding claim, in which the beam is microwave radiation.

12. A safety device as claimed in any of claims 1 to 10, in which the beam is ultrasound.

13. A safety device as claimed in any preceding claim, in which the beam is emitted through a beam-shaping element.

14. A safety device as claimed in claim 13, in which the shaping element has generally flat parallel side walls leading to a rectangular output mouth.

15. A safety device substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

16. A loading bay having associated therewith a safety device as claimed in any preceding claim.

17. A safety device however defined.