GB1568470A

GB1568470A - Street lighting control

Info

Publication number: GB1568470A
Application number: GB17593/78A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-05-03
Filing date: 1978-05-03
Publication date: 1980-05-29

Description

(54) STREET LIGHTING CONTROL (71) We, JOHN DAVEY of Tower House, St. Edmunds Lane, Gt. Dunmow, Essex and DAVID FENNER of 6, White Street, Gt. Dunmow, Essex, both British Subjects, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to improvements in or relating to the control of street lighting.

Various control devices have been employed in the past for automatically controll mg street lighting so as to switch the lamps on and off at the required times.

One known control device uses a photoelectric sensor arranged to sense the ambient light level and connected in circuitry for controlling the power supply to a lamp, so that the lamp is switched on when the ambient-light-level falls below a predetermined value and is switched off when the light level again reaches the predetermined value.

This known photoelectric device has the advantage that the lamp is controlled in accordance with the ambient light level and thus adjusts to variations in the hours of day-light. However, it has the drawback that the lamp is held on continuously during the hours of darkness and this is undesirable and inefficient in many cases.

Another known control device comprises a time switch arranged to control the power supply to the lamp, such time switch being driven by an electric motor and being provided with either an auxiliary clockwork motor or rechargeable electric power cells to ensure continuity of operation in the event of a failure in the mains power supply to the electric motor.

This known time switch device has the advantage that it can be set to extinguish the lamp for a period during the hours of darkness, but it is relatively expensive to manufacture and is relatively inflexible in operation in the sense that it does not automatically take into account variations in the hours of daylight.

It is an object of the present invention to provide an improved control device for street lighting which provides for a period of extinction of the lamp during the hours of darkness and which takes into account variations in the hours of daylight, yet which does not involve the expense of electrically driven time switches.

Accordingly, the present invention provides a control device for controlling a street lighting lamp, comprising a photoelectric detector for sensing the ambient light level and providing a first electrical output signal significant of the sensed light level, a radio receiver tuned to detect transmitted radio waves of a predetermined frequency and providing a second electrical output signal indicative of the presence of the said transmitted radio waves, and means for processing the said first and second electrical output signals to provide a control signal for energising the lamp only when the first and second signals indicate that the ambient light level is below a predetermined value and that the radio receiver is receiving the said transmitted radio waves.

Preferably, the said processing means comprises a first comparator for comparing the said first electrical signal with a first reference signal corresponding to the predetermined value of the light level, a second comparator for comparing the said second electrical signal with a second reference signal, and a logic gate having first and second inputs connected to the outputs of the first and second comparators respectively and delivering the said control signal.

Advantageously, the control device includes means for delaying operation of the lamp relative to a change in the first and/or second output signal. Conveniently, the delaying means are electrical delaying means connected between the first comparator and the logic gate.

In a preferred embodiment of the invention, the radio receiver of the control device is tuned to a predetermined broadcast radio frequency, so as to provide the second output signal during the broadcasting hours of that frequency.

In order that the invention may be readily understood, an embodiment thereof will now be described, by way of example, with reference to the accompanying drawing, in which the single Figure is a schematic block diagram of a street lighting control device embodying the invention.

The street lighting control device illustrated in the drawing comprises a photoelectric sensor 1 which is installed to sense the ambient light level in the street and has an output Z at which is delivered a first d.c.

output voltage significant of the sensed light level. The output Z of the sensor 1 is connected to one input 3 of a comparator 4 whose other input 5 receives a first d.c.

reference voltage corresponding to a predetermined light level. The output 6 of the comparator 4 delivers a digital voltage signal corresponding to logic 1 if the first output voltage is less than the first reference voltage and logic 0 if the first output voltage exceeds the first reference voltage.

A miniature receiver 7 of the lighting control device has no audio section and is narrow tuned to a national broadcast radio frequency, such as the B.B.C. 200KHZ frequency. The receiver 7 has an aerial 8 and employs fixed tuning. A second d.c.

output voltage derived from the receiver when receiving its predetermined frequency i.e. from the automatic gain control output 9 of the detector circuit of the receiver, is applied to one input 10 of a second comparator 11 whose other input 12 receives a second d.c. reference voltage at a level which is exceeded by the output 9 during reception of its predetermined frequency by the receiver 7. The output 13 of the comparator 11 delivers a digital voltage signal corresponding to logic 1 when the receiver output 9 exceeds the second reference voltage and logic 0 if the output 9 is less than the second reference voltage.

First and second adjustable electrical time delays 14 and 15 are connected in parallel to the output 13 of the second comparator 11.

The first delay 14 serves to delay a signal indicating reception of a broadcast signal by receiver 7, and the second delay 15 serves to delay a signal indicating termination of reception. These delays avoid the possibility of the lamps going off during a temporary interruption of broadcasting. and also enable timing of the operation of the lamp to be effected to some degree independently of the broadcasting radio station concerned.

These delays may be of crude construction and may be desirably so in order that all lamps do not operate simultaneously in any praticular street.

An AND gate 16 receives, at one input 17, the output signal of the first comparator 4 and, at its other input 18, the delayed output signal of the second comparator 11, and delivers, at its output 19, a control signal for controlling a switch 20 in the power supply circuit of the lamp. The AND gate 16 produces a control signal of logic 1, which operates the switch 20 to energise the lamp 21, only when its inputs 17 and 18 receive logic 1 signals, i.e. when the radio receiver 7 is receiving the predetermined broadcast frequency and the sensor 1 detects an ambient light level below the predetermined level. A logic 0 output from gate 16 causes switch 20 to return to its open position.

Accordingly, in operation, the above described control device acts to energise the lamp 21 only when the sensor 1 is dark and the receiver 7 detects the predetermined broadcast frequency. By suitable selection of the broadcast frequency. it can therefore be arranged that the lamp is extinguished for that period, for example 12.30 a.m. to 6.00 a.m., during the hours of darkness when the station broadcasting that frequency is off the air. It will be seen therefore that the present control device combines the advantages of sensitivity to the ambient light conditions and extinction of the lamp for a period during the hours of darkness.

Although, in the event of a power failure in the supply to the control device, the lamp will be turned off, the lamp will assume the correct condition once power is restored.

WHAT WE CLAIM IS: 1. A control device for controlling a street lighting lamp, comprising a photoelectric detector for sensing the ambient light level and providing a first electrical output signal significant of the sensed light level. a radio receiver tuned to detect transmitted radio waves of a predetermined frequency and providing a second electrical output signal indicative of the presence of the said transmitted radio waves, and means for processing the said first and second electrical output signals to provide a control signal for energizing the lamp only when the first and second signals indicate that the ambient light level is below a predetermined value and that the radio receiver is receiving the said transmitted radio waves.

2. A control device according to claim 1, wherein the said processing means comprises a first comparator for comparing the said first electrical signal with a first reference signal corresponding to the predetermined value of the light level, a second comparator

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. delaying means are electrical delaying means connected between the first comparator and the logic gate. In a preferred embodiment of the invention, the radio receiver of the control device is tuned to a predetermined broadcast radio frequency, so as to provide the second output signal during the broadcasting hours of that frequency. In order that the invention may be readily understood, an embodiment thereof will now be described, by way of example, with reference to the accompanying drawing, in which the single Figure is a schematic block diagram of a street lighting control device embodying the invention. The street lighting control device illustrated in the drawing comprises a photoelectric sensor 1 which is installed to sense the ambient light level in the street and has an output Z at which is delivered a first d.c. output voltage significant of the sensed light level. The output Z of the sensor 1 is connected to one input 3 of a comparator 4 whose other input 5 receives a first d.c. reference voltage corresponding to a predetermined light level. The output 6 of the comparator 4 delivers a digital voltage signal corresponding to logic 1 if the first output voltage is less than the first reference voltage and logic 0 if the first output voltage exceeds the first reference voltage. A miniature receiver 7 of the lighting control device has no audio section and is narrow tuned to a national broadcast radio frequency, such as the B.B.C. 200KHZ frequency. The receiver 7 has an aerial 8 and employs fixed tuning. A second d.c. output voltage derived from the receiver when receiving its predetermined frequency i.e. from the automatic gain control output 9 of the detector circuit of the receiver, is applied to one input 10 of a second comparator 11 whose other input 12 receives a second d.c. reference voltage at a level which is exceeded by the output 9 during reception of its predetermined frequency by the receiver 7. The output 13 of the comparator 11 delivers a digital voltage signal corresponding to logic 1 when the receiver output 9 exceeds the second reference voltage and logic 0 if the output 9 is less than the second reference voltage. First and second adjustable electrical time delays 14 and 15 are connected in parallel to the output 13 of the second comparator 11. The first delay 14 serves to delay a signal indicating reception of a broadcast signal by receiver 7, and the second delay 15 serves to delay a signal indicating termination of reception. These delays avoid the possibility of the lamps going off during a temporary interruption of broadcasting. and also enable timing of the operation of the lamp to be effected to some degree independently of the broadcasting radio station concerned. These delays may be of crude construction and may be desirably so in order that all lamps do not operate simultaneously in any praticular street. An AND gate 16 receives, at one input 17, the output signal of the first comparator 4 and, at its other input 18, the delayed output signal of the second comparator 11, and delivers, at its output 19, a control signal for controlling a switch 20 in the power supply circuit of the lamp. The AND gate 16 produces a control signal of logic 1, which operates the switch 20 to energise the lamp 21, only when its inputs 17 and 18 receive logic 1 signals, i.e. when the radio receiver 7 is receiving the predetermined broadcast frequency and the sensor 1 detects an ambient light level below the predetermined level. A logic 0 output from gate 16 causes switch 20 to return to its open position. Accordingly, in operation, the above described control device acts to energise the lamp 21 only when the sensor 1 is dark and the receiver 7 detects the predetermined broadcast frequency. By suitable selection of the broadcast frequency. it can therefore be arranged that the lamp is extinguished for that period, for example 12.30 a.m. to 6.00 a.m., during the hours of darkness when the station broadcasting that frequency is off the air. It will be seen therefore that the present control device combines the advantages of sensitivity to the ambient light conditions and extinction of the lamp for a period during the hours of darkness. Although, in the event of a power failure in the supply to the control device, the lamp will be turned off, the lamp will assume the correct condition once power is restored. WHAT WE CLAIM IS:

1. A control device for controlling a street lighting lamp, comprising a photoelectric detector for sensing the ambient light level and providing a first electrical output signal significant of the sensed light level. a radio receiver tuned to detect transmitted radio waves of a predetermined frequency and providing a second electrical output signal indicative of the presence of the said transmitted radio waves, and means for processing the said first and second electrical output signals to provide a control signal for energizing the lamp only when the first and second signals indicate that the ambient light level is below a predetermined value and that the radio receiver is receiving the said transmitted radio waves.

for comparing the said second electrical signal with a second reference signal, and a logic gate having first and second inputs connected to the outputs of the first and second comparators respectively and delivering the said control signal.

3. A control device according to claim 1 or 2, including means for delaying operation of the lamp relative to a change in the first and/or second output signals.

4. A control device according to claim 3 as appendant to claim 2, wherein the delaying means are electrical delaying means connected between the second comparator and the logic gate.

5. A control device according to any preceding claim, wherein the radio receiver of the control device is tuned to a predetermined broadcast radio frequency, so as to provide the second output signal during the broadcasting hours of that frequency.

6. A control device for controlling a street lighting lamp substantially as hereinbefore described with reference to the accompanying drawing.