GB2392326A

GB2392326A - System for monitoring street lighting

Info

Publication number: GB2392326A
Application number: GB0219412A
Authority: GB
Inventors: Christopher Laurie Malthouse
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-08-20
Filing date: 2002-08-20
Publication date: 2004-02-25
Also published as: GB0219412D0

Abstract

A device for monitoring whether a light bulb in a lamp post is working, and sending radio signals to a remote receiver to indicate the light bulb status. The device may detect the light output of the bulb, or may be plugged into the lamp post, between the bulb and socket, in order to detect the electric current passing through the bulb. The device may be powered by a solar cell and rechargeable battery, or by the power supply to the light bulb. Devices are installed into each of a large number of lamp posts, each device having its own unique ID code. After a fault is detected, a signal comprising the unique ID code is transmitted to the remote receiver, and thus the particular lamp post which has a faulty bulb can be detected remotely.

Description

System for monitoring street lighting The present invention relates to a

device and a method of monitoring street lighting, and in particular, to a device and a method for detecting whether a street light is working, and notifying a base station by means of radio transmission.

Detecting the failure of light bulbs, such as those in street lighting or traffic lights, has been a long standing problem. Traditionally, people would be employed to manually go round and check all the bulbs. This was slow and inefficient. A better solution was proposed in WO 00/76034. In this application, a device containing a radio transmitter and receiver was fitted to each lamp post. These allowed the formation of a wireless data transmission network, linking up the lamp posts. The lights could be switched on and offby a remote control station, and the network could also relay an error signal to the control station whenever a bulb failed.

The present invention provides a device for monitoring a light bulb, said light bulb being plugged into a light bulb socket which can supply power to said light bulb, said device comprising a detector for detecting the status of said light bulb; means for storing an ID code for identifying said device; and a transmitter for transmitting a signal for reception by a remote receiver, said signal being for identifying the device and indicating the status of the light bulb.

The status of a light bulb is whether it is on or off. It may also cover other potential fault conditions such as a dim light, a flickering light, the light bulb being lit during the day, or an intermittent fault.

Preferably, the device comprises a timer for controlling the time at which the signal is transmitted. Preferably, the device is built into a housing in which the detector, the transmitter, the means for storing an ID code, and the timer are mounted.

The device may contain separate means for generating a signal. Alternatively, the signal may be generated within one or more of the other components of the device.

The device of the invention may be powered by being connected to the power supply of the light bulb. Alternatively, the device may comprise a solar cell for powering it.

There may be power storage means provided, such as a rechargeable battery.

The detector may be a light detector or may be an electric power detector. Preferably, the electric power detector would detect the electric current supplied to the light bulb or the voltage drop associated with the light bulb.

The device may have a socket into which the light bulb can be plugged, and a connector to allow the device to be plugged into the light bulb socket. Thus the device may be interposed between the light bulb and the light bulb socket. Preferably the connector is ofthe same type of fitting as the light bulb fitting. However, alternatively, the connector may have a different type of fitting than the light bulb and may act as an adaptor to allow a light bulb of one size or type to be fitted into a socket of a different size or type. For example, this could allow a standard size of light bulb to be used with a non-standard lamp post.

Alternatively, the device may comprise means, such as a sticky pad, for fixing the device to a support located in the proximity of the light bulb.

The device may have its ID code inscribed on the outside of the housing. The ID code may be used in conjunction with the timer to generate a timed signal, the timing of which provides an indication of the identity of the device. Alternatively, the device may transmit a signal comprising the ID code.

The device may be configured to transmit a monitoring signal, the monitoring signal being sent at regular or irregular intervals to indicate the status of the light bulb, regardless of whether or not there is a fault. This monitoring signal may be transmitted at predetermined times.

Alternatively the device may be configured to transmit a fault signal after the light bulb has been detected to be faulty. The device may be configured to identify a flickering light, a dim light, or an intermittent fault, as well as to detect the light bulb being on or off. For example, a dim or flickering lint may be detected by a change in light bulb current, voltage or light output to the normal operating current, voltage or light output.

A flickering light may be detected by making a plurality of such measurements over a period of time, and detecting any fluctuations in value.

The transmitter may be configured to transmit electromagnetic waves, preferably in the VHF or UHF range. An analogue or a digital signal may be transmitted. The signal may be transmitted in spread spectrum mode.

A plurality of the devices, each having a unique ID code, may be used to monitor a plurality of light bulbs. Relay stations may be used to relay the signals to the remote receiver. The remote receiver may be part of a base station, which also comprises means for using the information from the signals received from a plurality of the devices to generate a list of the ID codes of faulty light bulbs.

The device may be used with light bulbs in street lighting, traffic lights, sign illumination lights, or security lights.

The device is advantageous over the prior art because it has a much simpler design, e.g.

it does not need a receiver. It will thus be a lot cheaper to manufacture.

Preferred embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 shows a device according to a first embodiment of the invention; Figure 2a shows a cross sectional view and Figure 2b shows a top view of a device according to a second embodiment of the invention;

Figure 3 shows an example of the invention in use with a plurality of lamp posts, a relay station and a base station; Figure 4 is a flow chart showing an example of a simple status-monitoring scheme; Figure 5 shows an example of the structure of a signal which could be transmitted by a device using the status-monitoring scheme of Figure 4; Figure 6 is a flow chart showing an example of a simple fault reporting scheme; Figure 7 shows an example of the structure of a signal which could be transmitted by a device using the fault reporting scheme of Figure 6; A first embodiment of the device is shown in Figure 1. The device comprises a housing 101. The housing 101 may be made, for example, from metal or from moulded plastic.

The device has a socket 125 in the housing into which the light bulb can be fitted. The socket 125 may be adapted to accommodate a screw top light bulb (with left handed or right handed thread), a bayonet type light bulb, or a plug in light bulb. The socket is electrically connected via a transformer 110 to a connector 120 in the housing. The connector fits into the light bulb socket of the lamp post, traffic light or other lighting device. Thus, in use, the device is interposed between the light bulb and the light bulb socket. The transformer 1 10 and a power detection unit 11 1 are located inside the housing. The transformer 110 is connected to the light bulb via the socket 125, to the light bulb power supply via the connector 120, and to the power detection unit 111. The power detection unit 111 may detect the current passing through the light bulb or may detect the voltage across the light bulb. From this information, the device determines whether the light bulb is on or off. The device may also detect other fault conditions such as if the light is dimmed or flickering. The transformer 110 is also used to provide a power source for the transmitter and for the electronics within the housing 101.

The housing contains means 102 for storing an ID code. The ID code allows identification of the device when a large number of similar devices are used to monitor the status of a large number of light bulbs at the same time. The means 102 for storing an ID code 102 may be in the form of a memory, with the ID code stored in binary format. The ID code is preferably unique to the device, and may be akin to a serial number. The device contains a transmitter 105, which may transmit fault signals for indicating the presence of a fault, monitoring signals for indicating the status of the light bulb whether or not there is a fault, or both monitoring and fault signal. A timer 108 is also located in the housing 101. This timer 108 provides timing signals which tell the transmitter 105 when to transmit the signal.

A second embodiment of the invention is shown in Figures 2a and 2b. Figure 2a shows a cross-sectional view through the device of the second embodiment, and figure 2b shows a top view of the device shown in Figure 2a.

The device of the second embodiment of the invention also has a housing 101. As in the first embodiment, a transmitter 105 and means 102 for storing an ID code are also present within the housing 101.

In this embodiment, a light detector 130 is provided to detect the status of the light bulb.

The light detector 130 is connected to the transmitter 105 to allow an indication of the amount of light detected to be transmitted. The device of this embodiment needs no physical connection with the light bulb or the light bulb socket. It is powered by a solar cell 135 which is used to generate electricity dig the day or whilst the bulb is brightly lit. The solar cell 135 is connected to a rechargable battery 140, for storing generated electricity. The rechargeable battery 140 is connected to the transmitted, and it can be used to power the transmitter 105 and the rest of the electronics inside the device. It is possible to have a device powered by a solar cell which does not use a battery. For example, such a device may transmit monitoring signals only when the light bulb is on.

The device may be provided with mounting means for attaching it to a support in the proximity of the light bulb. The mounting means may be a sticky pad 150, a screw, a nail or a clip. Alternatively, the device may be placed inside the lamp shade or casing of a lamp post or traffic lights without being physically attached.

In me device of the second embodiment, the device has an overall disclike shape. The solar cell 135 is mounted on one of the flat surfaces 138 of the disc, and the light detector 130 is mounted in the centre ofthe solar cell 135. The device is preferably mounted so that the light sensitive surface faces towards the light bulb.

The device contains a timer 108 which controls the times at which the transmitter 105 transmits. However, it is not necessary for the device to contain a timer. The device may be configured to transmit a signal only when the light detector detects no light.

During the day, the light detector will detect daylight. During the night, when the light bulb is working, the light detector will detect light from the light bulb. If a fault develops in the light bulb, no light will be detected during the night. The device may then repeatedly transmit its identity code whilst the light detector remains in darkness.

A multiple of devices may be configured to transmit on different frequencies or they may be configured to transmit using spread spectrum modes to avoid interference should two devices transmit at the same time.

A preferred use for the invention is to monitor whether or not the light bulbs in a large number of street lights are working. Figure 3 shows an example of a network of lamp posts 200, each lamp post 200 being fitted with a device according to the invention, for example, a device as shown in figure I or figure 2A and B. Each device transmits a radio signal 205 from the lamp post 200, indicating the status of the light bulb. The radio signals 205 may be detected directly at a remote receiver 230. Alternatively, they may be detected at a relay station 220 and forwarded on from the relay station 220 to the remote receiver 230. The relay station 220 may retransmit the signals without modification or it may add, for example, an area code to each signal to assist in determining the location of the lamp post 200.

The remote receiver 230 is connected to a computer 240. The computer 240 is provided with a database 250 containing information about the ID code of each device in the lamp post network and the location of the corresponding lamp post 200. This information may be accumulated when the devices are installed into the street lights 200. Preferably, each device has its ID code inscribed onto the outside of its housing 101. When a device is installed into a lamp post 200, the person installing it can take a note of the location of the lamp post 200, and the ID code of the device. These records are transferred to the computer database 250.

The computer 240 receives information from the receiver 230 as to which street lights are working or not working. The computer 240 then compiles a list of lamp post locations for which the light bulb must be replaced, using the information in the database 250.

Various types of signalling scheme are possible for reporting the status of the light bulb to a remote receiver. These schemes can be classified as status monitoring schemes, fault reporting schemes, or mixed schemes. In a status monitoring scheme, regular signals are transmitted to indicate the status of the street light bulb. In a fault reporting scheme, the devices transmit a signal only when a fault is detected. In a mixed scheme, a combination of status monitoring and fault reporting takes place, and both types of signal may be transmitted.

A monitoring scheme has the advantage that it is easier to tell if the detector itself should fail. In a fault reporting scheme, if a signal is not detected at the remote receiving station, it is to be believed that the light bulb is functioning correctly.

However, in a fault reporting scheme the number of necessary transmissions may be minimised and therefore a smaller amount of bandwidth may be needed.

Figure 4 is a flow chart showing an example of a simple status-monitoring scheme, which can be used with a number of different embodiments of the device provided that a timer is installed. In the first stage 401 of the flow chart of Figure 4, the street light switches on as it gets dark. This is controlled by the timer or control system already present within the street light. In this simple status-monitoring scheme, a status signal

is transmitted twice a night, although it is also possible for transmissions to occur either more or less frequently.

In order that all devices do not transmit simultaneously, each device has a delay time.

The delay time is preferably between zero and the desired interval between transmissions, and it does not need to be an integral number of minutes. Although the delay time may be set to the same value in a large number of devices, it is preferable to time the transmissions from different devices to be spread out over time. The delay time may be set to a random number within predefined limits during the manufacture of the device. Alternatively, the delay time may be generated based on the ID code of the device. For example, the delay time in minutes may be the last two digits of the ID code. A further possibility is that the delay time is randomly generated within the device and therefore changes each time a transmission is made.

In the example shown in Figure 4, a first transmission is made at midnight plus the delay time, and a second transmission is made at 2.00 am plus the delay time. At step 402, a check is performed to find out if the first transmission time has been reached. If this time has not yet been reached, the device waits until that time. At the first transmission time, the light bulb status is measured, as shown in step 403. A signal is then transmitted to indicate that bulb status along with the ID code of the device as shown in step 404. A similar process is repeated for the second nightly transmission.

As shown in step 405, the device waits until the time reaches 2.00 am plus the delay time. The light bulb status is again measured as shown in step 406 and a signal is transmitted 407 to indicate the status along with the ID code of the device.

This process is repeated on a nightly basis. The status signal may simply indicate whether the light bulb is on or off at that time. It may also indicate if the light is dim or flickering. Another possibility is that the device contains a memory and that monitoring is performed more than once, or even continuously, before each transmission. The results of the monitoring are stored in the memory. If a fault condition is detected in any of these measurements, a fault signal is transmitted. Otherwise, a status signal is transmitted to indicate that the light bulb is working. By this means, intermittent faults may also be detected.

The transmission times do not need to be at regular intervals and could be at random times. Transmission could also occur during the day and if the device was configured to store the status of the light bulb, it would be possible to transmit that stored signal only during the day.

Figure 5 shows a possible structure of the transmitted signal for the monitoring scheme of Figure 4. The first part of the transmitted signal comprises the ID code 450. This allows identification of the particular light bulb. The second part comprises the status indication 451. This may indicate "on" or "off', "faulty" or "working", or the specific type of fault condition which has been found.

Figure 6 is a flow chart showing an example of a simple fault reporting scheme. At the first step 501 the street light switches on as it gets dark. In step 502 the status of the light bulb is measured. In step 503 if the light bulb is working step 502 is repeated and the bulb status is measured again. The status may be monitored continuously or sampled at regular intervals.

If the bulb is not working, step 504 is performed and a signal is transmitted to indicate the ID code of the device and the status of the light bulb.

After failure of the light bulb, a signal may be transmitted immediately and/or continuously. Alternatively, a signal may be transmitted at regular intervals, for example once every hour after the light bulb has failed, or once every night. As in the process described in figure 4, a time delay system may be implemented so that if a fault occurs simulaneously in more than one light bulb, the error transmission signals are less likely to occur at the same time. A further possibility is that there may be a random element to the times at which a signal is transmitted after the light bulb has failed.

The signal transmitted by a simple fault reporting scheme such as that in Figure 6 may simply be the ID code 450 of the device itself, as shown in figure 7. Information about the status of the light bulb may also be sent, for example, giving an indication of which type of fault is present in the light bulb.

It is also possible to use a mixed fault reporting and status monitoring scheme. For example, a single status monitoring signal may be sent once per night. addition to this, an error signal may be sent if an error is detected. Such a scheme has the advantage of sending a regular cony rmation that the bulb is still working, whilst also minimising the amount of bandwidth needed for signal transmission.

Claims

CLAIMS:

1. A device for monitoring a light bulb, said light bulb being plugged into a light bulb socket which can supply power to said light bulb, said device comprising: a detector for detecting the status of said light bulb; means for storing an ID code for identifying said device; a transmitter for transmitting a signal for reception by a remote receiver, said signal being for identifying the device and indicating its status; and a timer for controlling the time at which said signal is transmitted.

2. A device as claimed in claim 1, said device further comprising a housing in which said detector, transmitter and timer are mounted.

3. A device as claimed in claim 1 or claim 2, wherein said device comprises means for connecting to the power supply of the light bulb.

4. A device as claimed in claim 3, wherein said device is powered by said power supply.

5. A device as claimed in any one of claims 1 to 4, wherein said device furler comprises a solar cell, and said device is powered by said solar cell.

6. A device as claimed in any one of the previous claims, further comprising power storage means for storing electricity for powering said device.

7. A device as claimed in claim 6, wherein said power storage means comprises a rechargable battery.

8. A device as claimed in any one of the previous claims, wherein said detector is a light detector.

9. A device as claimed in any one of claims 1 to 7, wherein said detector is an electric power detector.

10. A device as claimed in claim 9, wherein said electric power detector detects the electric current to said light bulb.

1 1. A device as claimed in any one of the previous claims, where said device comprises a connector for plugging into the light bulb socket, and a socket into which the light bulb can be plugged, such that the device may be interposed between said light bulb and said light bulb socket.

12. A device as claimed in any one of claims 1 to 10, wherein said device comprises means for attaching the device to a support located the proximity of the light bulb.

13. A device as claimed in claim 12, wherein said means for attaching comprises a sticky pad.

14. A device as claimed in any one of claims 1 to 13, wherein said ID code is inscribed on the outside of the housing

15. A device as claimed in any one of the previous claims, wherein said ID code is used in conjunction with said timer to generate a timed signal, the timing of said signal providing an indication of the identity of said device.

16. A device as claimed in any one of the previous claims, wherein said signal comprises said ID code.

17. A device as claimed in any one of the previous claims, wherein said device is configured to transmit a monitoring signal, said monitoring signal indicating the status of the light bulb.

18. A device as claimed in claim 17, wherein said monitoring signal is transmitted at predetermined tones.

19. A device as claimed in any one of the previous claims, wherein said device is configured to transmit a fault signal after said light bulb has been detected to be faulty.

20. A device as claimed in any one of the previous claims, wherein said device comprises means to identify a flickering light, a dim light, or an intermittent fault.

21. A device as claimed in any one of the previous claims, wherein said transmitter transmits radio waves in the VHF or UHF range of the electromagnetic spectrum.

22. A device as claimed in any one of the previous claims, wherein said signal is transmitted as a digital code.

23. A device as claimed in any one of the previous claims, wherein said signal is transmitted in spread spectrum mode.

24. A device as claimed in any one of the previous claims, wherein said light bulb is for one of the group of: a street light, a traffic light, a sign illumination light, a security light.

25. A plurality of said devices according to any one of the previous claims, each device having a unique ID code.

26. A relay station for relaying a signal from a device of any one of the previous claims.

27. A base station comprising: a receiver for receiving said signals from a plurality of devices according to any one of the previous claims; means for generating a list of ID codes of faulty light bulbs, based on said received signals.

28. A device for monitoring a light bulb, said light bulb being plugged into a light bulb socket which can supply power to said light bulb, said device comprising:

a detector for detecting the status of said light bulb; means for identifying an error condition from said status; means for storing an ID code for identifying said device; and a transmitter for transmitting a signal for reception by a remote receiver, said signal being for identifying the device and indicating its status.