GB2447912A

GB2447912A - Improvements in or relating to area lighting

Info

Publication number: GB2447912A
Application number: GB0705852A
Authority: GB
Inventors: Ernest Woollard
Original assignee: Lucy & Co Ltd W
Current assignee: Lucy & Co Ltd W
Priority date: 2007-03-27
Filing date: 2007-03-27
Publication date: 2008-10-01
Also published as: EP2130409A2; WO2008117072A2; WO2008117072A3; GB0705852D0

Abstract

A lighting control unit comprises a light sensor 14 and a wireless receiver 12, and is adapted to output a control signal 30 for activation of a lamp 36, such as a street light, when the light sensor detects a low light condition or the wireless receiver detects an incoming activation signal. The wireless receiver is preferably adapted to respond to an encoded signal, in order to prevent false activations. The wireless receiver can be adapted to distinguish two incoming signals, a first signal being the activation signal and a second signal on receipt of which the control unit is adapted to deactivate the lamp regardless of the state of the light sensor. This enables a further mode of operation in which the lamp is disabled, such as for maintenance work. Signals 8 and 20, output by the wireless receiver and the light sensor for activation of the lamp may be applied to an OR operator 22, and the output of the OR operator may be applied to an AND operator 28 along with the inverse of an over-ride signal 26, generated in response to receipt of the second signal by the wireless receiver. Generally, a radiofrequency receiver is the most suitable form of wireless receiver.

Description

Improvements in or relating to Area Lighting

FIELD OF THE INVENTION

The present invention relates to improvements in or relating to area lighting.

BACKGROUND ART

An important part of the routine maintenance of lighting schemes is to establish whether any lamps have failed, and (if so) which lamps. Current area lighting schemes generally use a photocell to switch on a lamp during the hours of darkness. Routine maintenance is, however, usually carried out during daylight hours. This means that the photocell system has to be overridden in order to see which lamps are not working.

Lamps are generally switched on by one of two methods. The first is by way of an override switch that can be operated to force the lights on. This does however require access to the electrical switch room of the site, which is a usually a secure area for which authorization is needed in order to gain access.

This process can take time, and there are sometimes problems with permissions such as in relation to lighting schemes for secure sites, dangerous areas etc. An alternative is to fool the photocell into thinking that it is actually night time, by placing an opaque object over the photocell. These photocells are usually located high up on buildings so that they have a good view of the sky, which makes them difficult to reach. Doing so also imposes a Health & Safety burden on the inspector, in that various restrictions on the use of ladders must be complied with, and the safety of personnel on the site must be considered.

Further, some photocells have day/night synchronization timers which means that it can take some time for the photocell to respond. All in all, while this process is superficially tempting, it is (in practice) very time consuming and inefficient.

SUMMARY OF THE INVENTION

It is clear from the above that it is not straightforward simply to switch the lamps on to see if any need replacing.

The present invention therefore provides, in a first aspect, a lighting control unit, comprising a light sensor and a wireless receiver, adapted to output a control signal that is active when the light sensor detects a low light condition or the wireless receiver detects an incoming activation signal.

The wireless receiver is preferably adapted to respond to an encoded signal, in order to prevent false activations.

The wireless receiver can be one adapted to distinguish two incoming signals, including a first signal being the activation signal and a second signal on receipt of which the control unit is adapted to de-activate the control signal regardless of the state of the light sensor. This enables a further mode of operation in which the lamp is disabled, such as for maintenance work.

In a second aspect, the present invention provides a lighting control unit comprising a wireless receiver adapted to output a first control signal that is active when an incoming signal is detected and a light sensor adapted to output a second control signal that is active when a low light condition is detected, and an OR operator to which the two control signals are delivered.

The wireless receiver can again be one that comprises two channels each adapted to detect an incoming signal. In this aspect, the channels can include a first channel adapted to output the first control signal and a second channel that is adapted to output an over-ride signal, the invert of which is delivered to an AND operator together with the output of the OR operator.

Generally, a radiofrequency receiver is the most suitable form of wireless receiver.

The lamp itself can be activated by a relay driven by the remainder of the control unit, in order to isolate the AC mains power from the control unit.

The present invention also provides an area lighting system incorporating a lighting control unit as defined above, and a Street light unit comprising an upright column and, at an upper region thereof, a lamp and such a lighting control unit.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described by way of example, with reference to the accompanying figures in which; Figure 1 shows a schematic circuit embodying the present invention; Figure 2 shows the unit installed in a street light; and Figure 2b is an enlargement of part of figure 2.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention include a low power radio receiver associated with the photocell unit, which can be used to override the photocell temporarily so that an inspection can take place to see which lamps are faulty.

A small transmitter unit can be used to send a coded signal to the photocell for this purpose. This transmitter unit can be kept by the site owner/representative (under lock & key if necessary) and given to the maintenance engineer so that the lamps can be switched on without the need to access the electrical fuse system, permissions can be acquired quickly from the site manager, and no dangerous techniques need be employed to override the photocells.

The benefits of doing so include; -Reduced on site maintenance time (& therefore cost) -Reduced health and safety risks -Existing systems can be upgraded by simply replacing the photocell unit -Lamps can be checked more often -Low installation costs -An inhibit function can be made available A block diagram of a typical system is shown in figure 1. This shows the receiver unit 10 included in the same volume as an existing photocell unit. The transmitter and receivers used will typically work at one of the licence-free radio channels such as 433 or 862 MHz. The actual frequency used will of course depend on the regulations for the country in which it is used. The antenna 12 for the radio receiver 10 can be provided as part of the PCB tracking, which will help to reduce the cost of the unit. A primary output 8 conveys a digital signal indicating whether the receiver unit 10 has detected an appropriate signal from a transmitter unit.

The photocell 14 delivers a signal level 16 to a comparator 18 which checks that the light level indicated by the signal level 16 is below a chosen threshold, and outputs a digital light level signal 20. This is then combined with the primary output 8 of the receiver 10 via an OR operation 22 so as to produce a lamp control signal 24 that is high if either it is dark or if an appropriate signal has been received by the receiver 10.

A second channel of the receiver 10 is defined as a lockout" mode. This allows for an inhibit (or lockout) signal which activates the secondary LOCKOUT output 26 of the receiver, and prevent the lamps from illuminating at all. This can be useful at times when maintenance work such as replacement of the bulb is in progress. The invert of the LOCKOUT signal 26 is combined with the lamp control signal 24 in an AND operation 28 so as to produce an output 30 that is fed to a relay drive 32 and to a relay 34. The relay 34 then controls the AC power to the lamp 36 via its switch contacts 38.

The photocell and control electronics is thus sufficiently simple and compact to fit on a circular PCB, in the same volume as an existing photocell unit and with the photocell located in the centre of the board. The lamp can therefore be switched on at any time and will not interfere with any day/night synchronisation timers.

Figure 2 shows the unit installed in a Street light. A column 50 supports an arm 52 on the end of which is a lamp 54. A control unit 56, shown in more detail in figure 2b, comprises a printed circuit board (PCB) 58 enclosed in a housing 60. A transparent window 62 is formed In the housing 60, directly over the PCB 58, and a light sensor 14 is mounted on the PCB beneath the window 62. The PCB 58 also carries the remainder of the logic circuitry shown in figure 1, and the aerial 12 formed as an elongate track on the PCB.

Incoming power cables 64, 66 are contained within the column 50 and are routed to the contacts of a dual pole relay 34. Power is also fed to a transformer 68 which delivers a low voltage DC supply to the PCB 58. Outgoing power cables 70, 72 are connected to the opposite side of the relay contacts and are routed within the arm 52 to the lamp 54.

It will of course be understood that many variations may be made to the above-described embodiment without departing from the scope of the present invention. For example, the radio receiver described above could be replaced with any form of receiver for a wirelessly transmitted signal.

Claims

1. A lighting control unit, comprising a light sensor and a wireless receiver, adapted to output a control signal that is active when the light sensor detects a low light condition or the wireless receiver detects an incoming activation signal.

2. A lighting control unit according to claim 1 in which the wireless receiver is adapted to respond to an encoded signal.

3. A lighting control unit according to any one of the preceding claims in which the wireless receiver is adapted to distinguish two incoming signals, a first signal being the activation signal and a second signal on receipt of which the control unit is adapted to de-activate the control signal regardless of the state of the light sensor.

4. A lighting control unit, comprising a wireless receiver adapted to output a first control signal that is active when an incoming signal is detected and a light sensor adapted to output a second control signal that is active when a low light condition Is detected, and an OR operator to which the two control signals are delivered.

5. A lighting control unit according to claim 4 in which the wireless receiver comprises two channels each adapted to detect an incoming signal, including a first channel adapted to output the first control signal and a second channel that is adapted to output an over- ride signal, the invert of which is delivered to an AND operator together with the output of the OR operator.

6. A lighting control unit according to any one of the preceding claims in which the wireless receiver is a radiofrequency receiver.

7. A lighting control unit according to any one of the preceding claims, including a relay driven by the remainder of the control unit thereby to activate a lamp.

8. An area lighting system incorporating a lighting control unit according to any one of the preceding claims.

9. A street light unit comprising an upright column and, at an upper region thereof, a lamp and a lighting control unit according to any one of claims 1 to 7.

10. A lighting control unit substantially as herein described with reference to and/or as illustrated in the accompanying figures.