Field

[0001 ] The present invention relates to a control system for a light source. Background

[0002] Lighting installations are commonly used to illuminate building interiors in work and domestic environments. A control system may be used to automatically control individual lights, or sets of lights, in a lighting installation in response to a variety of factors. This includes in response to persons or equipment moving in particular rooms or areas illuminated by lights and in response to changes to ambient light conditions.

[0003] A lighting control system is typically integrated directly into the internal circuitry used in an individual light. To install, the protective housing of the light is firstly opened up and the control system is then wired to the light's electronical components in the housing. These components include the light's power convertor in the housing so that low current DC electrical power may be supplied to the combinatorial logic circuitry of the control system. Significant time and effort is, therefore, required to integrate the control system.

[0004] In this context, there is a need for lighting control systems that can be quickly and easily retrofitted into existing lighting installations.

Summary

[0005] According to the present invention, there is provided a control system for a light source, the control system comprising:

a controller comprising an input and an output, wherein the input is configured to be connected directly to a mains supply of electricity and the output is configured to be connected to a power supply cable of the light source; and

at least one light sensor operatively coupled to the controller, wherein the light sensor is configured to measure an ambient light level of an environment illuminated by the light source,

wherein the controller is configured to vary a light output of the light source in response to the ambient light level measured by the light sensor. [0006] The controller may be configured to switch the light source on or off in response to the ambient light level measured by the light sensor.

[0007] The controller may be configured to switch the light source on when the ambient light level measured by the light sensor falls below a threshold level.

[0008] The controller may be configured to vary the light output of the light source until the ambient light level measured by the light sensor is at a target level.

[0009] The light source may comprise a dimming circuit and the controller may be configured to be connected to dimming wires of the dimming circuit.

[0010] The dimming circuit may comprise a digital control protocol and the controller may be configured to interface with the digital control protocol.

[001 1 ] The control system may further comprise a motion sensor and the controller may be further configured to vary the light output of the light source in response to motion detected by the motion sensor.

[0012] The control system may be configured to switch the light source on in response to motion detected by the motion sensor.

[0013] The control system may be configured to switch the light source off when the motion sensor has not detected any motion for a fixed period of time.

[0014] The control system may be configured to dim the light source to a particular level when the motion sensor has not detected any motion for a fixed period of time.

[0015] The motion sensor may comprise a passive infrared sensor.

[0016] The motion sensor may comprise a microwave sensor.

[0017] The motion sensor may comprise a camera.

[0018] The light sensor may be configured to attach to a heat sink of the light source.

[0019] The light sensor may be configured to attach to a reflector of the light source.

[0020] The measured ambient light level may be calibrated to a remotely measured ambient light level, measured by a mobile device. [0021 ] The control system may further comprise a memory and a processer operatively coupled to the memory, wherein the processor executes to record one or more light levels of the light source and one or more levels of electrical power supplied to the power supply cable over time.

[0022] The present invention further provides a light source having a control system as described above operatively coupled to the light source.

[0023] The light source may comprise a light-emitting diode.

[0024] The light source may be configured to be embedded into a ceiling of a building.

[0025] The present invention further provides a lighting system comprising a plurality of light sources and a plurality of control systems, wherein each of the control systems is as described above and is operatively coupled to at least one of the light sources.

Brief Description of Drawings

[0026] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

Figure 1 is an elevated side view of a control system for a light source according to an example embodiment of the invention;

Figure 2 is a schematic diagram of components that may be comprised in another example embodiment of the invention;

Figure 3 is a schematic diagram of various components that may be comprised in the controller of the control system of Figure 1 ;

Figure 4 is a schematic diagram of an alternative arrangement of various components that may be comprised in the control system of Figure 1 ;

Figures 5 illustrates various screens of a user interface of an application program executing on a mobile device that may be used in example embodiments of the invention; and

Figures 6A-6P illustrates various screens of a user interface of an application program executing on a mobile device that may be used in further example embodiments of the invention. Description of Embodiments

[0027] Referring to Figure 1 , a control system 10 for a light source 12 comprises a controller 14 comprising an input 16 and an output 18, wherein the input 16 is configured to be connected directly to a mains supply of electricity 20 and the output 18 is configured to be connected to a power supply cable 22 of the light source 12. The control system 10 further comprises at least one light sensor 24 operatively coupled to the controller 14, wherein the light sensor 24 is configured to measure an ambient light level of an environment illuminated by the light source 12. The controller 14 is configured to vary a light output of the light source 12 in response to the ambient light level measured by the light sensor 24.

[0028] More particularly, the mains supply of electricity 20 may comprise a power cable 17 having a male plug 27 for connection to a mains power socket 29. The power socket 29 may, in turn, be connected directly to a single-phase alternating current (AC) electrical power supply of a building or structure that the light source 12 is fitted to. For example, the power socket 29 may be directly connectable to the principal ring main circuit of the building or structure. To facilitate a direct connection to the mains supply of electricity 20, the input 16 may comprise live, neutral and earth terminals (not shown) configured for connection to respective live, neutral and earth wires of the power cable 17. Similarly, the output 18 of the controller 14 may also comprise live, neutral and earth terminals (not shown) configured for connection to respective live, neutral and earth wires of a further power cable having a female plug 31 for connection to the power supply cable 22 of the light source 12. The live, neutral and earth terminals of the input 16 and the output 18 may each be housed inside the controller 14.

[0029] The light source 12 may comprise a high bay light fitting of the type that is commonly fitted into building ceilings. For example, the light source 12 may comprise a high bay light fitting comprising a light emitting diode (LED) bulb, wherein the light fitting is embedded into, or suspended from, a ceiling 25. For dropped or suspended ceiling designs, the controller 14 may be disposed in a plenum or similar empty space formed immediately above the ceiling that the light source 12 is fitted to. For non-suspended ceiling designs, the controller 14 may be disposed in a cavity formed directly into the ceiling material near to the light source 12. The cavity may, for example, be hollowed out of the concrete or other construction material that the ceiling is made of. Alternatively, the controller 14 may be located away from the light source 12 in a separate room or other part of the building or structure. The light source 12 may be suspended from the ceiling 25 by a chain 33 with the controller 14 being suspended next to the chain 33. The chain 33 may extend downwardly from a rafter or other support member of the ceiling 25. The light source 12 may be suspended using an alternative means such as, for example, a pole extending downwardly from the ceiling 25.

[0030] The light sensor 24 is preferably secured in a position and orientation that enables the light sensor 24 to measure accurately an ambient light level of the environment illuminated by the light source 12. As illustrated in Figure 1 , the light sensor 24 may, for example, be attached in close proximity to the light source 12 but in a position where the light sensor 24 is not obstructed by the light source 12. If the light source 12 comprises a high bay light fitting, the light sensor 24 may be attached to a heat sink 35 or a reflector of the light fitting.

[0031 ] The controller 14 may be configured to operate with non-dimmable light sources 12. In such examples, the controller may be configured to switch the light source 12 on when the ambient light level measured by the light sensor 24 falls below a threshold level. Similarly, the controller 14 may switch the light source 12 off again when the ambient light level rises and meets or exceeds the threshold level.

[0032] The controller 14 may also be configured to operate with dimmable light sources 12, such as dimmable LED light bulbs. For example, the controller 14 may be configured to connect to dimming wires 26 of a dimming circuit of the dimmable light source 12. As shown in Figure 1 , the dimming wires 26 may be contained inside a single dimming cable extending between the controller 14 and the light source 12. The dimming wires 26 may be configured for plugged connection between the dimming circuit and the controller 14. The dimming circuit may comprise and implement a digital control protocol and the controller 14 may be configured to interface with the digital control protocol. The controller 14 may conform to a digital dimming standard, such as a digital addressable lighting interface (DALI) standard, and implement 1 -10 volt lighting control. The controller 14 may be configured to vary the light output of the light source 12 via the dimming wires 26 until the ambient light level measured by the light sensor 24 is at a target level (for example, at a target lux (Ix) level) or within prescribed tolerances of the target level. The controller 14 may make individual ambient light readings from the light sensor 24 and incrementally adjust the light output of the light source 12 until the target lux level is achieved. The controller 14 may make these measurements and adjustments at a rate of 300 times per second.

[0033] The control system 10 may also comprise a motion sensor 28 and the controller 14 may be configured to vary the light output of the light source 12 in response to motion detected by the motion sensor 28. The motion sensor 28 may comprise a passive infrared sensor, microwave sensor, camera or other sensing means adapted to detect motion of a person or equipment when moving through the environment that the light source 12 is intended to illuminate. As depicted in Figure 1 , the motion sensor 28 may be housed inside the same receptacle that contains the light sensor 24.

[0034] The controller 14 may be configured to vary the light output of the light source 12 in response to motion detected by the motion sensor 28. For example, the controller 14 may be configured to switch the light source 12 on when any motion is detected by the motion sensor 28. By way of further example, the controller 14 may be configured to increase the brightness of the light source 12 until a target luminosity level is read by the light sensor 24 when any motion is detected by the motion sensor 28. The controller 14 may also be configured to turn the light source 12 off after the motion sensor 28 has not detected any motion for a prescribed period of time. The controller 14 may, alternatively, be configured to dim the light source 12 to a particular level (for example, to 10% or some other proportion of the current output level) after the motion sensor 28 has not detected any motion for a prescribed period of time.

[0035] The controller 14 may comprise a memory (not shown) and a processer (not shown) operatively coupled to the memory, wherein the processor executes computer- executable instructions configured to implement a control program. The control program may be configured to measure various operating and performance data relating to the control system 10 during use, including in relation to the controller 14 and sensors 24,28, and to record these data on a computer-readable storage medium. These data may include ambient light level readings, detected motion and electrical current passing through the light source 12 at one or more designated time intervals during use. The types and amounts of data measured and recorded, and the frequency at which measurements are made, is governed by the storage capacity of the storage medium.

[0036] The control program may also be configured so that the user of the control system 10 may adjust operative parameters and settings of the controller 14. If the light source 12 is non-dimmable, then these parameters and settings may include the threshold ambient light level at which the light source 12 is automatically switched on or off. If the light source 12 is dimmable, the parameters and settings may include the target ambient light level to be attained by the light source 12 as measured by the light sensor 24.

[0037] The control program may also allow different operative parameters and settings of the control system 10 to be set for different calendar days and/or hours of the day. For example, the control program may allow the controller 14 to be configured to switch off the light source 12 automatically at night or keep the light source 12 switched off during certain time periods or between certain dates. The control program may also allow the controller 14 to enter an energy saving mode wherein the target ambient light level to be achieved by the light source 12, and other relevant operative parameters and settings of the control system 10, are set to values that cause the control system 10 to consume less power.

[0038] The memory device comprised with the controller 14 may serve as the computer- readable storage medium on which the operating and performance data and the operative parameters and settings are stored. Alternatively, the controller 14 may comprise a separate non-volatile storage means serving as the computer-readable storage medium. The information recorded on the computer-readable storage medium may be read at a later date using an external computing device that interfaces with the controller 14.

[0039] Referring to Figure 4, the control system 10 may further comprise a mobile device 30 for configuring and operating the controller 14, including for retrieving information stored on the computer-readable storage medium on the controller 14. The mobile device 30 may comprise a memory (not shown) and a processer (not shown) operatively coupled to the memory, wherein the processor executes computer- executable instructions configured to implement an application program. The application program may allow a user to make changes to settings and configurations on the controller 14.

[0040] The mobile device 30 and controller 14 may each implement a connection process that enables the respective devices to discover and communicate with each another. As part of the connection process, the controller 14 may be configured to recognise a prescribed sequence of light flashes using the light sensor 24 which, when detected, cause the controller 14 to enter a discoverable mode. The application program on the mobile device 30 may comprise functionality that causes a light on the mobile device 30 to emit the prescribed sequence of light flashes. The user may, therefore, aim the light of the mobile device 30 onto the light sensor 24 to trigger the discoverable mode. Once engaged, the mobile device 30 may connect to the controller 14 using a wireless communication means such as, for example, a Bluetooth, Zigbee or Wi-Fi based communication means.

[0041 ] After a connection between the mobile device 30 and controller 14 has been established, the user may use the application program to cause the controller 14 to execute a calibration process. Under the calibration process, the controller 14 takes a reading of the ambient light level using the light sensor 24 and, if necessary, makes adjustments to relevant settings of the controller 14, light sensor 24 and light source 12 to ensure that accurate ambient light levels can be measured.

[0042] The mobile device 30 may also comprise a remote light sensor (not shown) configured to measure the level of ambient light in the environment. The calibration process on the controller 14 may also make use of data recorded using the mobile device's 30 remote light sensor when calibrating the light sensor device 24 connected to the controller 14. These data may be transferred from the mobile device 30 to the controller 14 via the wireless communication means during the calibration process.

[0043] The remote light sensor may be a camera of the mobile device 30. The mobile device 30 and the light sensor 24 may be calibrated by comparing light readings from the light sensor 24 and the remote light sensor. The light level reading of the light sensor 24 may be correlated with an ambient light reading of the remote light sensor. Further, changes in light level of the light source 12 can be correlated to an actual effective change in the ambient light level at the location of the remote light sensor. This correlation may be used to calculate differences between actual light level and an expected light level, measured at the light source 12. For example, the control system may be calibrated by taking ten synchronised lux readings from both the light sensor 24 and the camera on the mobile device 30. The synchronised light readings may be implemented to build a calibration table. The calibration table may be implemented the controller 14 to adjust the light source output to ensure accurate ambient light levels. [0044] The application program executing on the mobile device 30 may also include functionality that enables the user to calibrate separately the mobile device's 30 light sensor. To enable this to occur, the control system 10 may also comprise a narrow beam LED torch that emits light at a known luminosity level. The user may shine the light emitted from the torch onto the mobile device's 30 light sensor during the calibration process. The application program may also comprise calibration functionality that enables the user to input a known luminosity level which they have measured independently using a separate lux meter.

[0045] Referring to Figure 2, the control system 10 may further comprise a remote database 32 that is hosted on a server accessible by the controller 14 and/or the mobile device 30 via the internet. The application program executing on the mobile device 30 may further comprise functionality that retrieves warranty information from the controller 14 and transmits this information to the database 32 for storage. This retrieval and transfer may occur automatically during the initial connection or calibration process of the controller 14 or may occur in response to the user specifically instructing the application program to perform these steps via a user interface presented on a display of the mobile device 30. The remote database 32 may comprise predetermined configurations for supported mobile devices. The application program may be configured to apply the correct preconfigured calibration to the mobile device 30 based on the type of mobile device being used.

[0046] The application program may further comprise functionality adapted to identify a user of the mobile device 30 and configure the control system 10 according to settings and parameters unique to the user stored on the mobile device 30. The identification means may comprise face, voice or fingerprint recognition technology or a passcode or password-based system.

[0047] The control system 10 may track and record the position of an identified user of the mobile device 30 as they move throughout the environment illuminated by the light source over a period of time. The application program may also comprise functionality that issues an alert or notification to the user if they have not moved for a specified period of time. This advantageously helps avoid to tiredness and fatigue when the control system 10 is deployed and used in a work environment. [0048] A plurality of light sources and a plurality of the control systems 10 may be combined together to form a lighting system network within a building or structure. Each of the control systems 10 in the network may be connected to one another wirelessly using a wireless communication means such as a Wi-Fi network. For example, Figure 2 depicts three separate premises each comprising its own lighting system network 34. Each network 34 comprises three of the control systems 10.

[0049] Each network 34 may be configured so that each control system 10 in the network 34 has and maintains the same set of operative parameters and settings. The application program executing on a mobile device 30 interfacing with a network 34 may comprise functionality that enables the common set of operative parameters and settings in the network to be set and modified simultaneously. This advantageously reduces the time taken to add and commission additional control systems to a network 34. Alternatively, each network 34 may be configured such that each control system 10 in the network 34 has and maintains its own set of operative parameters and settings. Each network 34 may also be configured so that each control system 10 in the network is able to collectively or individually detect motion of persons or equipment in the environment illuminated by the network's 34 light sources 12.

[0050] As shown in Figure 2, each network 34 may further comprise a gateway 36 configured to collect usage data from each control system 10 in the relevant network. These usage data may comprise electrical power usage data relating to the light sensors 24 and motion detectors 28 of each control system 10. The gateway 36 may also be configured to control operative settings of each control system 10 simultaneously. For example, the gateway 36 may be used to dim or turn each light source 12 of each control system 10 off automatically in response to an alarm triggered by a security system interfacing with the gateway 36. Similarly, the gateway 36 may be configured to trigger an alarm, and to switch on each light source 12 of each control system 10, in response to motion detected by a motion sensor 28 in the relevant network. The gateway 36 may be in communication with the remote database 32 via the internet and be configured to periodically aggregate and transmit usage data collected by the gateway 36 to the database 32 for storage. The database 32 may implement an application program interface (API) configured to make the stored usage data subsequently available to peripheral devices. [0051 ] Each network 34 may comprise a connection means configured to enable internet-of-things (loT) enabled devices to connect wirelessly to the network 34 and to each control system 10 in the network 34. The connection means may comprise the wireless communication means of the network 34 or it may comprise a modem connected to each controller 14 or to the gateway 36. The loT devices connecting to the network 34 may be configured to track people moving throughout the area or building illuminated by each of the light sources 12 in the network 34. The loT devices may be configured to ensure that an appropriate level of illumination is provided for particular work or activities carried out by people in the relevant area or building, including with regard to any particular stock, products or machinery operated or handled in the course of their work or activities.

[0052] Referring to Figure 3, there is shown a schematic diagram of various electrical and other components that may be comprised in the controller 14. The controller 14 may comprise a microcontroller 40 that interfaces with a clock 42, wherein the clock 42 is used by the controller 14 to control the sensors 24, 28 and light source 12 according to the time and date. The controller 14 may further comprise a dimming interface 44 for controlling the dimming circuit of the light source 12 and a sensor interface 46 for retrieving information measured by the light sensor 24. The controller 14 may further comprise a button 48 for engaging a test mode and an LED 50 configured to indicate the status of the controller 14. To facilitate direct connection to a mains supply 20 of electricity, the controller 14 may also comprise a voltage regulator 52, fuse assembly 54, AC power meter 56 and an AC power relay 58.

[0053] Referring to Figure 4, there is shown a schematic diagram of various electrical and other components that may be comprised in a further example controller 1 14. The controller 1 14 may comprise a microcontroller 140 for controlling the various electrical and other components. The controller 1 14 may comprise an electrical input 1 16 and an electrical output 1 18 which may, for example, be a 240V alternating current source. Connection between the input 1 16 and the output 1 18 may be controlled or switched, for instance, by means of a Triode for alternating current (TRIAC). The TRIAC may be controlled or switched by the microcontroller 140. The controller 1 14 may comprise power metering equipment, for example, voltage and/or current meters 156 for measuring power usage of, for example, the light source 12. [0054] The controller 1 14 and associated electrical and other components may comprise an AC to DC converter 151 , for converting power supplied at the input 1 16 to a logic level voltage. The logic level voltage may be regulated by a regulator 152, for supplying correct voltages to the logic level components, such as the microcontroller 140. The microcontroller 140 may be configured for Bluetooth communication with external devices. The microcontroller 140 may comprise a clock for controlling the electrical components according to time and date. The microcontroller 140 may be configured for receiving various other sensor inputs, which may, for example, comprise a temperature sensor input. The controller 1 14 may comprise a dimming interface 144 which may be connected to the microcontroller 140 by means of an optical isolator 145. The controller may comprise memory or other internal storage 148. The memory 148 may be configured to store logs and data for assisting with trouble shooting and/or reporting. The microcontroller 140 may be configured to receive sensor data from extended sensors 146, comprising, for instance, the light sensor 24 and/or the infrared sensor 28.

[0055] Figures 5 shows various screens of an example user interface that may be provided by the application program executing on the mobile device 30. The user interface may provide a first calibration screen 60 for calibrating a light sensor on the mobile device 30; a first network configuration screen 62 for adding the mobile device 30 and any connected controllers 14 to a lighting system network 34; a energy configuration screen 64 for setting energy saving modes on the control system 10 and the light output of the light source 12; second, third and fourth network configuration screens 66,68,70 for calibrating the sensors 24,28 connected to the controller 14; first and second flash control screens 72,74 for establishing a connection with a controller 14 or network gateway 36 and a reporting screen 76 for displaying statistical and other information recorded by the control system 10 on the controller 14 and/or the mobile device 30.

[0056] Figures 6A-6P show various screens of another example user interface that may be provided by the application program executing on the mobile device 30. The user interface may provide site creation screens 160a-160e for inputting and identifying the location of an installation where a control system 10 may be implemented. The user interface may provide first and second zone management screens 162a, 162b. Various control systems 10 at a site or location may be combined into a zone, control systems 10 within the same zone may be assigned the same calibration and energy management settings. The user interface may provide energy management and configuration screens 164a-164e. A screen may be configured to allow the user to set the desired light level for a zone and whether the zone is time controlled for switching on and off. Multiple control systems 10 can be added and removed from a zone, with each of the control systems 10 controlled at the group light level setting. The user interface may provide a calibration of light screen 168 which may display the ambient light level measured by the mobile device 30. The user interface may provide connection management screens 172a-172c for establishing and managing a connection between the mobile device 30 and the control system 10. The user interface may further provide screens to display energy usage of each controller system 10 or a combination of control systems 10 within a group.

[0057] The input 16 and output 18 of the controller 14 may be connected directly to, respectively, a mains supply of electricity 20 and a mains power cable 22 of a light source 12. The control system 10 may, therefore, advantageously be retrofitted into light installations that have already been connected to a mains supply of electricity including, for example, to the ring main circuit of a building. In particular, the controller 14 advantageously does not need to be connected to a power convertor used by the light source 12 during installation. The controller 14 is a discreet device that can be fitted in a plug-and-play manner to dimmable and non-dimmable lighting installations with minimal re-wiring and installation work.

[0058] Embodiments of the present invention provide control systems that are useful for controlling the output of light sources in response to changes in ambient lighting conditions and the presence or absence of persons in the vicinity of light sources.

[0059] As used herein, a "processor" refers to a device capable of executing instructions encoding arithmetic, logical, and/or I/O operations. In one illustrative example, a processor may follow Von Neumann architectural model and may include an arithmetic logic unit (ALU), a control unit, and a plurality of registers. In a further aspect, a processor may be a single core processor which is typically capable of executing one instruction at a time (or process a single pipeline of instructions), or a multi-core processor which may simultaneously execute multiple instructions. In another aspect, a processor may be implemented as a single integrated circuit, two or more integrated circuits, or may be a component of a multi-chip module (e.g., in which individual microprocessor dies are included in a single integrated circuit package and hence share a single socket). [0060] For the purpose of this specification, the word "comprising" means "including but not limited to", and the word "comprises" has a corresponding meaning.

[0061 ] The above embodiments have been described by way of example only and modifications are possible within the scope of the claims that follow.