GB2107097A - Artificial illumination - Google Patents

Abstract

A carriageway (10) is illuminated, or the illumination is increased, when a vehicle activates a detector. A first detector comprises an electrically conductive loop (14) and a source (15) of alternating current which responds to a change in the inductance of the loop. Further detectors (17, 18) provide signals in response to a change in a beam of electromagnetic radiation from projectors (17, 19) which radiate energy across the carriageway and are adapted to detect reflection of that energy. A control device (13) is adapted to energise the light sources (11) in accordance with signals received from at least one of the detectors in an appropriate sequence for a predetermined period. <IMAGE>

Description

SPECIFICATION Artificial illumination From one aspect, the present invention relates to a method of controlling the artificial illumination of a region. The invention also relates to apparatus for use in the method.

According to a first aspect of the invention, there is provided a method of controlling the artificial illumination of a region wherein illumination of the region is initiated or increased in response to the presence in a predetermined detection field of a mobile body.

According to a second aspect of the invention, there is provided apparatus for illuminating a region comprising a light source arranged for illuminating the region when energised and control means for controlling energisation of the light source, wherein the control means includes a detector for detecting the presence in a predetermined detection field of a mobile body.

The detection field and the region may coincide substantially completely, may partially overlap or may be adjacent. The detection field may fall entirely within the region. A field and a region which have one of these relations are described herein as being associated. The region may be a plurality of times larger than the associated detection field.

The control means may be arranged for initiating energisation of or for varying the level of energisation of the light source.

The detector may be adapted to detect persons or animals or vehicles or all of these.

The region may be a road or other region intended for use by vehicular traffic. Alternatively, the region may be a corridor or other region intended for use by pedestrians.

The detector may be adapted to respond only to a sequence which comprises a change in the detection field and a substantial reversal of that change and which sequence occurs within a predetermined interval of time, for example a sequence caused by movement of a body past the detector at a speed above a threshold speed.

The detection field may be an electrostatic or magnetic field. Alternatively, electro-magnetic radiation or sound waves may be transmitted across the field to be incident on the detector either when there is no body present in the field or when there is a body present in the field. The electro-magnetic radiation may be radar waves or infra-red radiation.

The field may be of elongated form, the radiated energy being confined to a beam.

Alternatively, energy may be radiated widely to establish the field.

In a case where the field is an electrostatic or magnetic field, the intensity of the field at a selected point may be substantially unvarying, whilst there is no mobile body present in the field.

Alternatively, the intensity of the field at a selected position may vary in a cyclic manner, for example be an alternating field. The field may be one in which the presence of a body can be detected by an inductive effect, in which case the detector would comprise an electrical inductor carrying a signal which is modified by the presence of a body in the field.

The field is preferably established by the control means.

The control means may include a sensor which is sensitive to the intensity of illumination in said region and is adapted to prevent energisation of the light source under the control of the detector if the intensity of illumination is above a predetermined threshold.

Examples of apparatus embodying the second aspect of the invention and used in a method according to the first aspect of the invention will now be described, with reference to the accompanying drawing which illustrates diagrammatically a pian view of a road equipped with the apparatus.

The road illustrated in the accompanying drawing includes a carriageway 10 above which light sources 11 are supported by lamp posts 12, the light sources being arranged in a row extending along the length of the carriageway and being spaced apart from each other. The light sources are connected with a mains electrical supply (not shown) by switching devices (also not shown). For controlling operation of the switching devices, there is provided a control centre 13. In a case where the switching devices are contained in the control centre, this is connected by electrical conductors with the light sources. In a case where the switching means are contained in respective posts 12, the switching means are connected by electrical conductors (not shown) with the control centre.

There is also connected electrically with the control centre 13 a number of detectors. A first of the detectors comprises an electrically conductive loop 14 buried in the carriageway 10 and a source 1 5 of alternating current which passes through the loop 1 4. The source 1 5 includes means which respond to a change in the inductance of the loop 14 to provide to the control centre 13 an output signal indicating the presence of a metallic body on the carriageway above the loop.

A second of the detectors, 1 6, is adapted to respond to incidence of a beam of electromagnetic radiation on the detector. A projector 1 7 for projecting across the carriageway 10 a beam of electro-magnetic radiation having a wave length to which the detector 1 6 responds is positioned at the opposite side of the carriageway 10 to the detector and arranged so that the beam from the projector 1 7 is incident on the detector 1 6 when there is no mobile body on the carriageway between the projector and detector.

The detector is connected with the control centre 13 to provide thereto a signal when the beam is interrupted by a mobile body, which may be a person or a vehicle.

At a position spaced along the road from the detector 16, there is an identical detector 18, opposite to which there is a projector 1 9 identical to the projector 1 7. The detector 1 8 also is connected with the control centre 13.

A further detector is incorporated in a device 20 positioned beside the carriageway and also incorporating a transmitter. The device 20 radiates energy across the carriageway and the detector of the device is adapted to detect reflection of that energy from a body on the carriageway back to the device. The device then provides a signal to the control centre 13. The device 20 may emit ultrasonic waves or electro-magnetic radiation.

The device may provide an output signal to the control centre 13 only when a body moves within the detection field.

The control centre 13 comprises logic circuits adapted to energise the light sources 11 in accordance with signals received from at least one of the detectors 1 5, 1 6, 1 8 and 20. For example, if a vehicle passes over the loop 14, the light sources 1 la to 11 dwhich are beyond that loop, assuming travel of the vehicle in the normal direction along the carriageway, may be energised for a predetermined period which would normally be of sufficient duration to enable the vehicle to pass beyond the light source 11 d.The arrangement may be such that the light sources 1 C and 1 dare energised only if the inductance of the loop 14 is changed in one direction and then changed by a substantially equal amount in the opposite direction within a time period corresponding to that required for a vehicle required to travel over the loop.

Alternatively, the light sources 1 a to 1 d may be energised when the vehicle interrupts the beam between the projector 1 7 and detector 1 6. The light sources may be energised for a predetermined period or extinguished when the beam between the projector 1 9 and the detector 18 is interrupted.

The control centre may be adapted to determine from the sequence in which the detectors provide signals to the control centre the direction in which a vehicle is travelling along the carriageway and to illuminate the light sources 11 in an appropriate sequence. Thus, if the beam from the projector 1 9 is interrupted before the beam from the projector 1 7 is interrupted, the light sources to the left of the projector 17, as viewed in the drawing, may then be energised.

The device 20 may be adapted to respond to abrupt changes in the detection field, for example changes caused by entry of a vehicle into the detection field.

The detection field of each detector illustrated in the drawing has a relatively small extent along the length of the carriageway. Alternatively, the control means may include one or more detectors having a detection field which extends along the carriageway for a distance considerably greater than the width of the carriageway. For example, a detector may be positioned beside the carriageway at a bend so that its detection field extends from the bend along a straight length of carriageway to a subsequent bend.

The latter arrangement or an arrangement illustrated in the drawing may be used to control the illumination of a footpath or corridor.

Claims (6)

1. A method of controlling the artificial illumination of a region wherein illumination of the region is initiated or increased in response to the presence in a predetermined detection field of a mobile body.

2. Apparatus for illuminating a region comprising a light source arranged for illuminating the region when energised and control means for controlling energisation of the light source, wherein the control means includes a detector for detecting the presence in a predetermined detection field of a mobile body.

3. Apparatus according to Claim 2 wherein the control means is adapted to respond by energising the light source or increasing the level of energisation of the light source to a sequence which includes a change sensed by the detector and a substantial reversal of that change, which sequence occurs within a predetermined interval of time.

4. A method according to Claim 1 substantially as herein described with reference to the accompanying drawing.

5. Apparatus according to Claim 2 substantially as herein described with reference to the accompanying drawing.

6. Any novel feature or novel combination of features disclosed herein or in the accompanying drawing.