Lighting arrangement with memory retention

Abstract

A processing system for a lighting arrangement configured to output light when powered by an input power from an external power source. The processing system is configured to control the output of light by the lighting arrangement when also powered by the input power. Particularly, when the processing system is operating in a sequence control mode, the processing system is configured to control the lighting arrangement to output light in accordance with a time-dependent lighting sequence, which describes desired characteristics of the light output by the lighting arrangement over a duration of time.

Description

[0001] Lighting arrangement with memory retention

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to the field of lighting arrangements, and in particular to lighting arrangements comprising memory and / or memory devices.

[0004] BACKGROUND OF THE INVENTION

[0005] Lighting systems and arrangements such as streetlighting in urbans areas, and artificial lighting in offices, may be configured to output light according to a desired timedependent lighting routine or sequence. For example, streetlights may be programmed to implement a dimming sequence to reduce their brightness during later periods of the night when there is less street activity, thus reducing power consumption.

[0006] To execute such lighting routines, lighting arrangements require a method of tracking / timing progression through the routine in order to perform desired changes at corresponding times. Often lighting arrangements comprise an internal clock that is synced with the local time when the lighting arrangements are installed and / or during a calibration procedure. The lighting arrangements may thus perform the lighting routine with reference to a time from the internal clock.

[0007] However, in the event of a power cut or power cycle, the internal clock may reset and become out-of-sync with the local time, thus resulting in the lighting arrangements performing the lighting routine incorrectly, i.e., performing desired changes at incorrect times. There is thus a desire for a lighting arrangement with a memory retention function that allows, in the event of a power failure, the light arrangement to “remember”, or otherwise retrieve, a progression through a lighting routine prior to the power failure.

[0008] SUMMARY OF THE INVENTION

[0009] The invention is defined by the claims.

[0010] According to examples in accordance with an aspect of the invention, there is provided a processing system for a lighting arrangement. The lighting arrangement is configured to be powered by an input power from an external power source and output light. The processing system is configured to also be powered by the input power and control the output of light by the lighting arrangement. The processing system is further configured to, during a sequence control mode of operation, control the lighting arrangement to output light according to a time-dependent lighting sequence, and periodically store, in a non-volatile memory, a progress indicator that indicates a progress through the time-dependent lighting sequence. Responsive to an end of a failure of the input power, the processing system is configured to retrieve, from the non-volatile memory, the progress indicator and resume control of the lighting arrangement, according to the time-dependent lighting sequence, responsive to the progress indicator.

[0011] The present invention provides a processing system for controlling the output of light by a lighting arrangement. Specifically, the processing system is configured to control the light output of the lighting arrangement according to a time-dependent lighting sequence. Additionally, the processing system and the lighting arrangement are both powered by an input power from an external power source, such as a power grid and / or a mains supply.

[0012] The time-dependent lighting sequence is a desired routine to be performed by the lighting arrangement over a period of time. For example, the time-dependent lighting sequence may describe the intensity of light, and / or the color of light, output by the lighting arrangement as a function of time. Said period of time may refer to a particular period of the day, e.g., between 07:00 PM to 07:00 AM, or a length (of time) of the time-dependent lighting sequence, e.g., 12 hours.

[0013] Such a time-dependent lighting sequence may be used, for example, in streetlights to define a dimming sequence to be performed by the streetlights at night, such as reducing the intensity of light output by the streetlights during later periods of the night when less cars are on the road.

[0014] The processing system may track the progression of the time-dependent lighting sequence via a clock / timer or counter that may indicate to the processing system a current progress of the time-dependent lighting sequence. For example, the clock or counter may indicate a current time of the day (e.g., 11:47 PM) or a current time in the lighting sequence (e.g., 132 minutes from the beginning of the lighting sequence) or a current percentage of progression through the lighting sequence (e.g., 55%). Particularly, it is understood that such a clock or counter (and by extension the processing system) may not receive, or not be configured to receive, a real time input (e.g., via wireless signals) indicating a live / true time of the day as set by international standards, e.g., Greenwich Mean Time. Accordingly, in the event of a failure of the input power, such as a power cut or a power cycle in which the lighting arrangement and the processing system both lose power, the clock or counter may reset or otherwise lose the current progress. Thus, once the input power is restored, i.e., an end to the failure of the input power, the processing system may resume the time-dependent lighting sequence at an incorrect time, e.g., the start of the lighting sequence.

[0015] It is therefore proposed that, while controlling the lighting arrangement to perform the lighting sequence, the processing system is configured to periodically store, in a non-volatile memory, a progress indicator that indicates the (current) progress through the time-dependent lighting sequence. Thus, following the end of the failure of the input power, the processing system is able to retrieve, from the non-volatile memory, the (stored) progress indicator such that the processing system may resume the time-dependent lighting sequence at an appropriate point / time. More specifically, the processing system is configured to resume control of the lighting arrangement, according to the time-dependent lighting sequence, responsive to the retrieved progress indicator.

[0016] In some examples, the progress indicator may be a time stamp that indicates a time in the time-dependent lighting sequence. For example, the time stamp may comprise a time of the day, e.g., 12:20 AM, or an amount of time from the beginning of the timedependent lighting sequence, e.g., 45 minutes.

[0017] Additionally, or alternatively, controlling the lighting arrangement to output light according to the time-dependent lighting sequence may comprise controlling the intensity of light output by the lighting arrangement according to the time-dependent lighting sequence. For example, the lighting sequence may specify (at a particular time) an absolute intensity or brightness of light to be emitted by the lighting arrangement, e.g., 3000 lumens, or a percentage of a maximum intensity or brightness of the lighting arrangement, e.g., 70%.

[0018] In some examples, the lighting arrangement may comprise an ambient light sensor configured to measure a light level in the vicinity of the lighting arrangement. In such cases, the processing system may be configured to receive the light level (from the ambient light sensor), compare the light level to a threshold value, and, responsive to the light level being below the threshold value, operate in the sequence control mode.

[0019] In other words, the processing system may be configured to only control the lighting arrangement to output light according to the time-dependent lighting sequence when the (ambient) light level is below the threshold value. For example, this may coincide with the beginning of a period of darkness, e.g., dusk, being a point in time when it is desirable for the lighting arrangement to be outputting light.

[0020] Furthermore, responsive to the light level being above the threshold value, the processing system may be configured to operate in a different operating mode. For example, the processing system may be configured to operate in a light suppression mode, where the processing system is configured to stop the lighting arrangement outputting light.

[0021] In other words, following the light level being or rising above the threshold value, the processing system may be configured to stop the luminaire outputting light, e.g., stopping the lighting sequence. For example, this may coincide with the beginning of a period of brightness, e.g., dawn, being a point in time when it is deemed unnecessary for the luminaire to be outputting light.

[0022] In some examples, the time-dependent lighting sequence may comprise a plurality of lighting segments, each lighting segment comprising a segment of time of the time-dependent lighting sequence. For example, each lighting segment may split the lighting sequence into segments of time describing a different light intensity to be output by the lighting arrangement. Alternatively, or additionally, each lighting segment may comprise a segment of time of equal length, e.g., splitting the lighting sequence into 1-hour segments.

[0023] Additionally, resuming control of the lighting arrangement responsive to the progress indicator may comprise identifying a progress segment, being a lighting segment containing the progress indicated by the progress indicator. In other words, the progress segment corresponds to the lighting segment that the progress of the time-dependent lighting sequence was in immediately prior to the failure of the input power.

[0024] Furthermore, resuming control of the lighting arrangement responsive to the progress indicator may further comprise determining a target progress point responsive to the progress segment, wherein the target progress point indicates a progress of the timedependent lighting sequence at which to resume control of the lighting arrangement. In other words, the target progress point indicates where in the time-dependent lighting sequence the processing system should resume control of the lighting arrangement.

[0025] More specifically, responsive to the progress segment, the target progress point may be set to be equal to either the progress indicator, or a progress corresponding to a beginning of the lighting segment immediately after the progress segment.

[0026] Put another way, the processing system may either resume the time-dependent lighting sequence at the point that it last stopped, i.e., the progress given by the progress indicator, or may skip ahead to the next lighting segment of the lighting sequence. Using the latter approach, the processing system may skip a portion of the lighting sequence, which may be preferable to account for time lost during the failure of the input power.

[0027] The above determination may be responsive to properties of, or preferences for, the progress segment, e.g., that the processing system should always skip to the next lighting segment if there was a failure of the input power during the progress segment.

[0028] In some examples, the processing system may receive the progress indicator to store in the non-volatile memory from a tracker, the tracker being configured to define the progress through the time-dependent lighting sequence. Additionally, following a failure of the input power, the tracker may determine the progress indicator, for example, by timing for how long the processing system has resumed controlling the lighting arrangement according to the time-dependent lighting sequence and adding this time to the target progress point.

[0029] Also provided is a controller for a lighting arrangement. The controller comprising the processing system according to the above disclosure and the non-volatile memory for storing the progress indicator.

[0030] In some examples, the controller may be configured to physically connect to the lighting arrangement. The controller therefore may function as a module to be added to a lighting arrangement, e.g., a driver, that subsequently allows the luminaire to be controlled to perform the lighting sequence.

[0031] Additionally, or alternatively, the non-volatile memory may further store the time-dependent lighting sequence, and the processing system may be configured to, prior to controlling the lighting arrangement, retrieve the time-dependent lighting sequence from the non-volatile memory.

[0032] The time-dependent lighting sequence may be initially stored in the memory during a calibration of the controller and / or when the controller is paired with a particular lighting arrangement. Furthermore, the lighting sequence may be defined at said point of calibration and / or may be customizable by a user. Following from the latter, the user may be able to customize and / or change the lighting sequence at a later time by accessing the lighting sequence in the memory.

[0033] Further provided is a method for controlling the output of light by a lighting arrangement configured to be powered by an input power from an external power source. The method comprises controlling the lighting arrangement to output light according to a timedependent lighting sequence, and periodically storing, in a non-volatile memory, a progress indicator that indicates a progress through the time-dependent lighting sequence. Responsive to an end of a failure of the input power, the method further comprises retrieving, from the non-volatile memory, the progress indicator, and resuming control of the lighting arrangement, according to the time-dependent light sequence, responsive to the progress indicator.

[0034] There is also provided a computer program product comprising computer program code means which, when executed on a processing system connected to a lighting arrangement, cause the processing system to perform all of the steps of the method according to the above disclosure.

[0035] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

[0036] BRIEF DESCRIPTION OF THE DRAWINGS

[0037] For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0038] Fig. 1 illustrates a controller comprising a processing system for a lighting arrangement according to an embodiment;

[0039] Fig. 2 shows a graph describing an example time-dependent lighting sequence; and

[0040] Fig. 3 shows a flowchart illustrating a proposed method.

[0041] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The invention will be described with reference to the Figures.

[0043] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, systems and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

[0044] The invention provides a processing system for a lighting arrangement configured to output light when powered by an input power from an external power source. The processing system is configured to control the output of light by the lighting arrangement when also powered by the input power. Particularly, when the processing system is operating in a sequence control mode, the processing system is configured to control the lighting arrangement to output light in accordance with a time-dependent lighting sequence, which describes desired characteristics of the light output by the lighting arrangement over a duration of time.

[0045] Additionally, while in the sequence control mode, the processing system is configured to periodically store, in a non-volatile memory, a progress indicator that indicates a current position / time in, i.e., a progress through, the time-dependent lighting sequence.

[0046] In the event of a failure of the input power, i.e., the processing system and the lighting arrangement stop receiving the input power, the processing system and the lighting arrangement both stop being powered. In other words, the lighting arrangement stops outputting light and stops being controlled by the processing system. Similarly, the progression of the time-dependent lighting sequence stops.

[0047] In response to an end of the failure of the input power, i.e., the processing system and the lighting arrangement start receiving the input power again, the processing system is configured to retrieve, from the non-volatile memory, the (last stored) progress indicator. The processing system then resumes control of the lighting arrangement to output light (again) according to the time-dependent lighting sequence, responsive to the progress indicator. In other words, the processing system resumes the time-dependent lighting sequence at a position / time (in the time-dependent lighting sequence) determined from the retrieved progress indicator.

[0048] Figure 1 shows a simplified example of a controller 100, comprising a processing system 110 coupled to a non-volatile memory 120, and a lighting arrangement 150 configured to output light.

[0049] The lighting arrangement 150 may comprise a single lighting element (i.e., a luminaire) or may comprise a plurality of lighting elements, such as a (connected) array of lighting elements. Furthermore, the lighting arrangement 150 may comprise one or more light sources 160 which may be wholly arranged on a single lighting element or may be distributed among a plurality of lighting elements.

[0050] The processing system 110 is configured to couple to, and control aspects of, the lighting arrangement 150. More specifically, the processing system 110 is configured to (at least) control the output of light by the lighting arrangement 150. For example, the processing system 110 may couple to the one or more light sources 160 of the lighting arrangement 150 and control the output of light from the lighting arrangement 150 by controlling a driving signal (e.g., an electrical current) provided to the one or more light sources 160.

[0051] In accordance with the above, controlling the light output of the lighting arrangement 150 will be understood to mean controlling the one or more light sources 160 of the lighting arrangement 150.

[0052] The processing system 110 may be configured to couple to the lighting arrangement 150 (or more specifically to elements of the lighting arrangement 150) via elements of the controller 100.

[0053] For example, the processing system 110 may couple to the lighting arrangement 150 via an interface (not visible in Figure 1) of the controller 100. More specifically, the interface may be configured to connect the controller 100 to the lighting arrangement 150 such that a physical connection (e.g., a continuous electrical connection) is made between the processing system 110 and elements of the lighting arrangement 150. In other words, the controller 100 may be configured to physically connect, via the interface, to the lighting arrangement 150.

[0054] Put another way, when the controller 100 is connected to the lighting arrangement 150 via the interface, the processing system 110 may form a wired connection with elements of the lighting arrangement 150. In this way, the processing system 110 may communicate with elements of the lighting arrangement via (direct) electrical signals.

[0055] It will be appreciated that, dependent on the configuration of the interface, the controller 100 may or may not be permitted to be detached (i.e., disconnected) from the lighting arrangement 150. For example, the interface may comprise an adaptor that permits the controller 100 to be “plugged-in” to a corresponding socket / port of the lighting arrangement 150. The interface may therefore provide a detachable connection between the controller 100 and the lighting arrangement 150. Alternatively, the interface may comprise a soldered connection between (electrical elements ol) the controller 100 and the lighting arrangement 150. Accordingly, such a connection may not permit detachment of the controller 100 from the lighting arrangement 150, e.g., without breaking the controller and / or lighting arrangement.

[0056] Alternatively, (or additionally) the processing system 110 may couple to the lighting arrangement 150 via a wireless transmitter and receiver of the controller 100 (not visible in Figure 1) for sending and receiving wireless signals. More specifically, the wireless transmitter and receiver may couple (via sending and receiving wireless signals) to a further wireless transmitter and receiver of the lighting arrangement 150 (not visible in Figure 1). In this way, the processing system 110 may communicate with (i.e., couple to) elements of the lighting arrangement 150 through said wireless signals.

[0057] Both the processing system 110 (or more generally the controller 100) and the lighting arrangement 150 are configured to be powered by (i.e., receive) an input power from an external power source 190. In particular, the processing system 110 may only control the light output of the lighting arrangement 150 when powered by the input power. Similarly, the lighting arrangement 150 may only output light when powered by the input power. Additionally, in the event of a failure of the input power, i.e., the external power source 190 stops providing the input power to the processing system 110 and the lighting arrangement 150, both the processing system 110 and the lighting arrangement 150 will become unpowered.

[0058] The processing system 110 may be configured to operate in different operating modes / modes of operation, where each operating mode defines a different way of controlling (the characteristics ol) the light output by the lighting arrangement 150. In particular, the processing system 110 may be configured to operate in a sequence control mode, in which the processing system 110 is configured to control the lighting arrangement 150 to output light according to a time-dependent lighting sequence, describing the desired characteristics of light output by the lighting arrangement 150 over a period and / or duration of time.

[0059] For example, the time-dependent lighting sequence may describe an intensity / brightness of light, and / or a color / wavelength of light, output by the lighting arrangement as a function of time. Furthermore, the time-dependency of the lighting sequence may refer to an absolute time-dependency, where a time in the lighting sequence refers to a time from a beginning / start point (i.e., a zero point) of the lighting sequence, or a real / relative time-dependency, where a time in the lighting sequence refers to a (local) time of the day, e.g., 11:00 PM.

[0060] In some examples, the time-dependent light sequence may be described by a continuous function that defines a smooth change in a characteristic of the light output by the lighting arrangement 150 (e.g., an intensity) as a function of time. Alternatively, the timedependent light sequence may be described by a piecewise function that defines a characteristic of the light output by the lighting arrangement 150 over discrete periods / durations of time (as shown in Figure 2).

[0061] The processing system 110, when in the sequence control mode of operation, thus controls and adjust (characteristics ol) the light output by the lighting arrangement 150 as a function of time according to the time-dependent lighting sequence. In other words, the processing system 110 controls the lighting arrangement 150 to perform the time-dependent lighting sequence.

[0062] In some examples, the processing system 110 may be preconfigured (e.g., during manufacture, when connected to the lighting arrangement 150, and / or during a calibration procedure) with a particular (i.e., specific) time-dependent lighting sequence. In other words, the particular time-dependent lighting sequence may be “hard-wired” into the processing system 110, such that the processing system 110 is configured to only control the lighting arrangement 150 according to the particular time-dependent light sequence.

[0063] Alternatively, the processing system 110 may retrieve the time-dependent lighting sequence from the non-volatile memory 120. As such, the processing system 110 may perform any time-dependent lighting sequence depending on what is stored in the nonvolatile memory 120. Particularly, the time-dependent lighting sequence, while in the nonvolatile memory 120, may be accessed and modified, e.g., by a user.

[0064] The processing system 110 may be configured to enter the sequence control mode (and therefore control the lighting arrangement 150 to perform the time-dependent lighting sequence) at a specific time, e.g., as given by a start time of the time-dependent lighting sequence. Additionally, the processing system 110 may be configured to exit (i.e., stop operating in) the sequence control mode at a later time, e.g., as given by an end time of the time-dependent lighting sequence. Such an approach may be appropriate when the timedependency of the lighting sequences refers to a relative (local) time.

[0065] For example, the processing system 110 may comprise an internal clock synced to a local time. The processing system 110 may thus be configured to enter the sequence control mode and begin the time-dependent lighting sequence when the time given by the internal clock reaches the start time of the time-dependent lighting sequence. Additionally, the processing system 110 may be configured to exit / stop operating in the sequence control mode when the time given by the internal clock reaches an end time of the time-dependent lighting sequence, thus corresponding to the lighting arrangement 150 having performed the entirety of the time-dependent lighting sequence.

[0066] Alternatively, the processing system 110 may be configured to enter / operate in the sequence control mode responsive to a measured (ambient) light level. To be more specific, the lighting arrangement 150 may comprise an ambient light sensor 170 configured to measure a light level (e.g., an illuminance, brightness) in the vicinity of the lighting arrangement 170. Such a system is common in streetlighting, where it is desirable for the streetlights to only emit light when the ambient light level is below a threshold (i. e. , when it is sufficiently dark).

[0067] Accordingly, the processing system 110 may be configured to receive the light level measured by the ambient light sensor 170 and compare the light level against a threshold value. In response to the light level being below the threshold value, corresponding to the ambient light level in the vicinity of the lighting arrangement 150 being sufficiently low / dark, the processing system 110 may operate in the sequence control mode and thereby control the lighting arrangement 150 to begin outputting light according to the timedependent lighting sequence.

[0068] In response to the light level being above the threshold value, the processing system may instead be configured to operate in a light suppression mode and stop the lighting arrangement 150 outputting light. Such a scenario may correspond to the ambient light level in the vicinity of the lighting arrangement 150 being sufficiently high that it would be unnecessary / undesirable / wasteful for the lighting arrangement 150 to be outputting light.

[0069] It will be understood that the processing system 110 may continuously or periodically receive the light level as measured by the ambient light sensor 170. While in the sequence control mode and therefore performing the time-dependent light sequence, should the light level rise above the threshold value, the processing system 110 may thus change to operate in the light suppression mode, thereby stopping the lighting arrangement 150 outputting light, and simultaneously ending the time-dependent lighting sequence. This may correspond to ending the time-dependent lighting sequence “early”, i.e., before an end (time) of the time-dependent lighting sequence.

[0070] The processing system 110, when configured to receive the light level, may thus be configured to control the lighting arrangement 150 to output light according to the time-dependent lighting sequence only during periods of darkness / low ambient light.

[0071] The processing system 110 may be configured to track a progress through, and / or a position in, the time-dependent lighting sequence using a tracker 130, for example, formed as part of the controller 100. More specifically, the processing system 110 may receive a progress indicator, which indicates a current progress through (and therefore a current position in) the time-dependent lighting sequence, from the tracker 130.

[0072] In some examples, the tracker 130 may be timer that tracks a time progression through the time-dependent light sequence, i.e., for how long the processing system 110 has been controlling the lighting arrangement 150 to perform the time-dependent lighting sequence. In other examples, the tracker 130 may be clock that tracks a real-time corresponding to a time position in the time-dependent lighting sequence. The progress indicator may hence be a time stamp indicating a time (position) in the time-dependent lighting sequence, such as an amount of time from a beginning (i.e., zero point) of the timedependent lighting sequence, e.g., 50 minutes. Alternatively, the time stamp may correspond to a real / local time, e.g., 11 :30 PM.

[0073] In further examples, the tracker 130 may alternatively (or additionally) track an (expected) percentage progression through the time-dependent lighting sequence, e.g., using a (calibrated) timing circuit. The progress indicator may hence be a percentage indicating a percentage progression / position in the time-dependent lighting sequence.

[0074] Accordingly, the processing system 110 may monitor progression through the time-dependent lighting sequence from the progress indicator received from the tracker 130 and, consequently, adjust the characteristics of the light output by the lighting arrangement 150 in response to the progress indicator referenced against the time-dependent lighting sequence.

[0075] Alternatively, the processing system 110 may comprise its own tracking device, such as a timing circuit or the previously mentioned internal clock, which the processing system 110 uses to track progress of the time-dependent lighting sequence, e.g., by generating a progress indicator.

[0076] It will be understood that the tracker 130 (and any other tracking or timing device comprised by the controller 100 or the processing system 110) is not configured to receive a live / real-time input of a current (local) time. Particularly, any form of reference time and / or reference point required for determining a time / progression of the timedependent lighting sequence is preprogrammed into the tracker 130 and / or provided during a calibration procedure.

[0077] Accordingly, should the tracker 130 become unpowered, e.g., due to a failure of the input power, the reference time / point may be lost, or the tracker 130 may reset or otherwise become unsynchronized with a local time. Consequently, the current progress for the time-dependent lighting sequence may also be lost, resulting in the processing system 110 controlling the lighting arrangement 150 to perform the time-dependent lighting sequence incorrectly (e.g., changing the characteristics of the output light at incorrect times).

[0078] To overcome this problem, the processing system 110, while in the sequence control mode, is further configured to periodically store the progress indicator, e.g., as received from the tracker 130, in the non-volatile memory 120. In this way, the progress indicator is “saved” (i.e., not lost) following a failure of the input power, particularly owing to the non-volatile character of the memory 120. The processing system 110 is then configured to retrieve the stored progress indicator from the non-volatile memory 120 once the input power is restored, or in other words, in response to an end of the failure of the input power.

[0079] Examples of non-volatile memory include flash memory (NAND flash, SSD), ROM, PROM (EPROM, EEPROM), and optical / magnetic disk (CD, HDD).

[0080] Subsequently, in response to the retrieved progress indicator, the processing system 110 resumes control of the lighting arrangement 150 to continue performing the timedependent lighting sequence. Specifically, the processing system 110 resumes the timedependent lighting sequence from a time / position in the time-dependent lighting sequence dependent on the retrieved progress indicator. For example, as will be further explained later, the time-dependent lighting sequence may either be resumed at a time / position equal to the progress indicator, or a time / position after the progress indicator. In other words, the timedependent lighting sequence will not be resumed at a time / position before the progress indicator.

[0081] While in the sequence control mode, the processing system 110 stores the progress indicator in the non-volatile memory 120 periodically, i.e., at predefined time intervals (e.g., 30 seconds, 5 minutes, 30 minutes) after previously storing the progress indicator.

[0082] This periodicity may be set, for example, by the tracker 130. More specifically, the tracker 130 may be configured to transmit to the processing system 110 (or the processing system 110 may be configured to retrieve from the tracker 130) the progress indicator at the predefined time intervals. The processing system 110, upon receiving the progress indicator, may then automatically store the progress indicator in the non-volatile memory 120.

[0083] Alternatively, this periodicity may be set by the processing system 110 itself. Particularly, the processing system 110 may continuously receive the progress indicator from the tracker 130, but only store the progress indicator in the non-volatile memory 120 at the predefined time intervals.

[0084] As another alternative, the time-dependent lighting sequence may define times or time intervals for which the processing system 110 should store the progress indicator in the non-volatile memory 120.

[0085] After resuming control of the lighting arrangement 150 following a failure of the input power, the processing system 110 continues to periodically store the progress indicator in the non-volatile memory 120. In particular, it will be understood that the progress indicator now refers to a progress in the time-dependent lighting sequence after the progress achieved / performed (by the lighting arrangement 150) immediately before the failure of the input power. In other words, following the failure of the input power, the progress indicator is not reset to a start / zero point of the time-dependent lighting sequence, but rather is a continuation of the progress stored / record in the non-volatile memory 120 prior to the failure of the input power.

[0086] Using the above approach, no matter how many times a failure of the input power occurs, or how long the failure last, the time-dependent lighting sequence will always be performed chronologically, i.e., the processing system 110 will never control the lighting arrangement 150 to revert / reset to an earlier / already performed part / time of the timedependent lighting sequence.

[0087] In order to accurately track the progress through the time-dependent lighting sequence following a failure of the input power, the processing system 110 may be configured to provide the tracker 130 with the determined time / position that the timedependent lighting sequence is resumed at / from. From the received time / position, the tracker 130 may then set an appropriate start / reference point from which to continue tracking the progress through the time-dependent lighting sequence.

[0088] As previously mentioned, the processing system 110 may be configured to stop operating in (i.e., exit) the sequence control mode (and therefore stop controlling the lighting arrangement 150 according to the time-dependent lighting sequence) at a specific (end) time, or in response to a light level rising above a threshold. Responsive to exiting the sequence control mode, the processing system 110 may be further configured to erase the progress indicator stored in the non-volatile memory 120 or set the stored progress indicator to a start / zero point of the time-dependent lighting sequence, thus “resetting” the stored progress.

[0089] Figure 2 shows an example of a time-dependent lighting sequence described by a piecewise function. Specifically, time-dependent lighting sequence 200 of Figure 2 describes an intensity of light (I) output by a lighting arrangement (when controlled by a processing system during a sequence control mode of operation) as a function of time (t) over a 12-hour period.

[0090] The processing system may control the lighting arrangement to start outputting light according to the time-dependent lighting sequence 200 at a particular time, or in response to a light level (measured by an ambient light sensor) falling below a threshold value. The processing system may then continue to control the lighting arrangement to perform the time-dependent light sequence 200 for the full 12-hour duration, or may end the time-dependent lighting sequence 200 early in response to the light level rising above the threshold value.

[0091] In some examples, such as in Figure 2, and particularly when described by a piecewise function, the time-dependent lighting sequence may comprise a plurality of lighting segments. Each lighting segment comprises a discrete segment of time from the time-dependent lighting sequence and therefore describes a proportion of the time-dependent lighting sequence. For example, each lighting segment may be (described by) a piece of a piecewise function that, overall, describes the time-dependent lighting sequence.

[0092] In Figure 2, the time-dependent lighting sequence 200 has been segmented into four primary lighting segments P1-P4. In particular, each primary lighting segment describes an intensity of light to be emitted by the lighting arrangement over a time period. Note, in the present example, the intensity is shown as remaining constant during each primary lighting segment. However, this need not be the case, and, in other examples, the intensity (or any other characteristic of light) may vary within a single primary lighting segment. Additionally, each primary lighting segment in Figure 2 covers a 3-hour duration, however, in other examples, each primary lighting segment may cover a duration of time different from 3-hours, and different primary lighting segments may cover different durations of time.

[0093] Furthermore, some primary lighting segments in Figure 2 are split into secondary lighting segments (e.g., Pl split into Sl. l and SI.2) that further segment the timedependent lighting sequence 200 into smaller time segments. The purpose of these secondary lighting segments will be discussed later.

[0094] Note, the designation of primary and secondary regarding the lighting segments of the time-dependent lighting sequence 200 is purely for illustrative and descriptive purposes and does not comprise a strict framework by which to describe / reference the segmentation of a time-dependent lighting sequence into lighting segments. For example, the 9 (secondary) lighting segments shown in Figure 2 could instead have been labelled sequentially from 1 to 9, thereby negating the primary and secondary labels.

[0095] The intensity described by each primary lighting segment in Figure 2 is given as a fraction of a reference intensity Io. The reference intensity may be a default intensity of the lighting arrangement, e.g., a nominal intensity of light output by the lighting arrangement when operating under “normal” conditions or when not being controlled by the processing system, and / or may be a maximum intensity of the lighting arrangement, e.g., a maximum possible intensity of light that may be emitted by the lighting arrangement.

[0096] The time-dependent lighting sequence 200 thus instructs how the processing system should control the intensity of light output by the lighting arrangement as a function of time with reference to the reference intensity Io. To be explicit, at the beginning of the time-dependent lighting sequence 200, i.e., in primary lighting segment Pl, the controller is instructed to control the lighting arrangement to output light with an intensity equal to the reference intensity Io. In subsequent primary lighting segments P2 and P3, the intensity of light output by the lighting arrangement is decreased (by the controller) to %Io and !4Io, respectively. Finally, in primary lighting segment P4, the intensity is increased back to %Io.

[0097] The time-dependent lighting sequence 200 may represent a dimming sequence to be implemented in a streetlighting system during nighttime. In particular, at the beginning of the night, i.e., dusk, the intensity of light output by the streetlighting system may be set to a maximum (represented by primary lighting segment Pl) as this is expected to be the period of the night with the greatness level of street activity, e.g., from pedestrians and cars. Later in the night, as the level of street activity decreases, the streetlighting system may gradually dim, i.e., decrease the intensity of emitted light, (represented by primary lighting segments P2 and P3) to reduce on power consumption. Finally, at the end of the night / early hours of the morning, the intensity of light emitted by the streetlighting system may increase again (represented by primary lighting segment P4) to account for an increase in street activity from people travelling to work.

[0098] It will be understood, however, that the time-dependent lighting sequence may take may different forms other than that presented in Figure 2 and may be used in settings other than streetlighting. For example, the time-dependent lighting sequence may be configured for an artificial lighting system in an office building to describe a desired intensity of light output by the artificial lighting system over the course of a day, dependent on factors such as the time of day and the expected level of activity (e.g., number of people) inside the office building.

[0099] While controlling the lighting arrangement to perform the time-dependent lighting sequence 200, the processing system is configured to store, in a non-volatile memory, a progress indicator that indicates a progress through the time-dependent lighting sequence 200. Particularly, the progress indicator may be a time stamp that indicates a time (position) in the time-dependent lighting sequence 200. Furthermore, following an end of a failure of an input power that powers the processing system and the lighting arrangement (during which the processing system stops controlling the lighting arrangement) the processing system is configured to retrieve the progress indicator and resume control of the lighting arrangement responsive to the (retrieved) progress indicator. Specifically, the processing system controls the lighting arrangement to resume the time-dependent lighting sequence 200 at a time (position) determined from the retrieved progress indicator.

[0100] The progress indicator, retrieved by the processing system, may be associated with a particular lighting segment in the time-dependent lighting sequence 200, dependent on where in the time-dependent lighting sequence 200 the progress indicated by the progress indicator appears. In other words, the lighting segment associated with the progress indicator is the lighting segment that the lighting arrangement was outputting light according to when the input power failed.

[0101] For example, a progress indicator between 0-3 hours may be associated with the primary lighting segment Pl, being the primary lighting segment that contains the progress indicator (or more specifically the progress indicated by the progress indicator). Moreover, a progress indicator between 2-3 hours may also be associated with the secondary lighting segment SI.2.

[0102] The lighting segment associated with the progress indicator may be labelled as the progress segment. Specifically, the progress segment is the (secondary) lighting segment that contains the progress through (i.e., the position in) the time-dependent lighting sequence 200 as indicated by the progress indicator.

[0103] In some examples, resuming control of the lighting arrangement responsive to the progress indicator may comprise identifying the progress segment associated with the progress indicator. Furthermore, a target progress point, being a progress / time (position) in the time-dependent lighting sequence 200 at which to resume control of the lighting arrangement, may be determined responsive to the identified progress segment.

[0104] In particular, each secondary lighting segment may be associated with different rules for how to resume the time-dependent lighting sequence 200, i.e., how to determine the target progress point.

[0105] For example, if the time-dependent lighting sequence 200 was stopped (due to a failure of the input power) near the start of a primary lighting segment, it may be desirable for the time-dependent lighting sequence 200 to be resumed substantially close to the same time / progress position that it was stopped at. In other words, it may be desirable to set the target progress point to be equal to the (retrieved) progress indicator.

[0106] Accordingly, if the time-dependent lighting sequence 200 stops in / during a secondary lighting segment at the start of a corresponding primary lighting segment (e.g., Sl. l, S2.1 or S3.1) the processing system may be instructed, when resuming control of the lighting arrangement, to set the target progress point equal to the progress indicator. Put another way, the processing system may be instructed to resume the time-dependent lighting sequence 200 at the time / position in the sequence that it stopped at due to the failure of the input power.

[0107] The above is indicated in Figure 2 by the triangular (“play”) symbols in the secondary lighting segments Sl. l, S2.1 and S3.1 (and the primary light segment P4). As such, if the progress segment is any of S 1.1 , S2. 1 , S3. 1 or P4, the target progress point is set to be equal to the progress indicator.

[0108] In another instance, however, it may be desirable for the time-dependent lighting sequence 200 to be resumed at a time / progress position later than when it was stopped, e.g., to account for time lost during the failure of the input power. Accordingly, for certain secondary lighting segments (e.g., SI.2, S2.2, S2.3, S3.2 or S3.3) the processing system may be instructed, when resuming control of the lighting arrangement, to set the target progress point equal to a time / progress at the beginning of the next lighting segment. For example, if the time-dependent lighting sequence 200 is stopped during secondary lighting segment SI.2, the target progress point may be set to be equal to 3 hours, corresponding to the beginning of secondary lighting segment S2.1.

[0109] The above is indicated in Figure 2 by the curved (“skip”) arrow in the secondary lighting segments SI.2, S2.2, S2.3, S3.2 and S3.3. As such, if the progress segment is any of SI.2, S2.2, S2.3, S3.2 or S3.3, the target progress point is set to be equal to a progress corresponding to a beginning of the secondary lighting segment immediately after the progress segment.

[0110] Figure 3 shows a flowchart describing a proposed method 300 for a processing system. Specifically, the method 300 describes how the processing system may control a lighting arrangement to output light.

[0111] The method 300 may begin with a step 310 of determining if a light level, as measured by an ambient light sensor of the lighting arrangement, is below a threshold value. Consequently, in response to the determination of step 310, the processing system may be configured to operate in one of two (or more) modes of operation. For example, in response to the light level being above the threshold value (i.e., a negative determination in step 310) the processing system may be configured to operate in a light suppression mode and the method 300 may progress to a step 315 of stopping the lighting arrangement from outputting light. Such a scenario may correspond to the ambient light level being sufficiently high in the vicinity of the lighting arrangement that it is considered unnecessary for the lighting arrangement to be outputting light.

[0112] Alternatively, in response to the light level being below the threshold value (i.e., a positive determination in step 310) the processing system may be configured to operate in a sequence control mode and the method 300 may progress to a step 320 of controlling the lighting arrangement to output light according to a time-dependent lighting sequence. Such a scenario may correspond to the ambient light level being sufficiently low in the vicinity of the lighting arrangement that it is considered necessary for the lighting arrangement to be outputting light.

[0113] The method 300 further comprises a step 330 of periodically storing, in a nonvolatile memory, a progress indicator 390 that indicates a (current) progress through the timedependent lighting sequence. Specifically, the processing system only performs step 330 while in the sequence control mode and while controlling the lighting arrangement according to step 320. Additionally, though step 330 has been depicted in Figure 3 as being after step 320, it will be understood that step 330 is performed at the same time as step 320.

[0114] Notably, the (stored) progress indicator 390 may be updated / overwritten with a new (current) progress indicator every time step 330 is performed.

[0115] While performing step 320, the method 300 may also comprise a step 340 of determining whether to continue to control the lighting arrangement to output light according to the time-dependent lighting sequence. Particularly, step 340 may be responsive to whether or not an end of the time-dependent lighting sequence has been reached.

[0116] Accordingly, in response to reaching the end of the time-dependent lighting sequence, the processing system may change to operating in the light suppression mode and the method may progress to step 315. Alternatively, if the end of the time-dependent lighting sequence has not been reached, the processing system may continue to control the lighting arrangement to perform the time-dependent lighting sequence, i.e., to continue step 320.

[0117] The method may further comprise a step 350 of determining if the light level is still below the threshold value. Specifically, in response to the light level rising above the threshold value (i.e., a negative determination in step 350) the processing system may change to operating in the light suppression mode and the method may progress to step 315. Alternatively, if the light level has not risen above the threshold value, the processing system may continue to control the lighting arrangement to perform the time-dependent lighting sequence, i.e., to continue step 320.

[0118] It will be understood that, while depicted in Figure 3 as being sequential, steps 340 and 350 may be performed at the same time as step 320. Additionally, steps 340 and 350 may be performed continuously (i.e., the processing system may continuously monitor whether there is a negative determination to steps 340 and 350) or periodically alongside step 320.

[0119] The method 300 may also comprise a step 360 of determining if there has been a failure of an input power that powers both the processing system and the lighting arrangement. In response to a negative determination in step 360 (i.e., a power failure not occurring) the processing system may continue to perform step 320.

[0120] Alternatively, step 360 may have a positive determination in response to a failure of the input power, i.e., the processing system and the lighting arrangement becoming unpowered. In such an event, it will be understood that the processing system will stop performing step 320 and the lighting arrangement will stop outputting light.

[0121] Subsequently, in response to an end of the failure of the input power, i.e., the processing system and the lighting arrangement becoming powered, the method 300 comprises a step 370 of retrieving the (stored) progress indicator 390, i.e., the progress indicator last stored in the non-volatile memory before the failure of the input power.

[0122] Additionally, the method 300 comprises a step 380 of resuming control of the lighting arrangement, according to the time-dependent lighting sequence, responsive to the retrieved progress indicator 390. More specifically, step 380 comprises controlling the lighting arrangement to resume performing the time-dependent lighting sequence at a time / position in the time-dependent lighting sequence determined from the progress indicator 390.

[0123] Following step 380, the method 300 returns to step 320 and the processing system continues to control the lighting arrangement according to the time-dependent lighting sequence from the time / position determined from the retrieved progress indicator 390. The processing system also continues to periodically store the progress indicator 390 in the non-volatile memory corresponding to the current progress in the time-dependent lighting sequence.

[0124] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

[0125] In some alternative implementations, the functions noted in the block diagram(s) or flow chart(s) may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.

[0126] Functions implemented by a processor may be implemented by a single processor or by multiple separate processing units which may together be considered to constitute a "processor". Such processing units may in some cases be remote from each other and communicate with each other in a wired or wireless manner.

[0127] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0128] A computer program may be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

[0129] If the term "adapted to" is used in the claims or description, it is noted the term "adapted to" is intended to be equivalent to the term "configured to". If the term "arrangement" is used in the claims or description, it is noted the term "arrangement" is intended to be equivalent to the term "system", and vice versa.

[0130] Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A processing system (110) for a lighting arrangement (150) configured to be powered by an input power from an external power source (190) and output light, the processing system being configured to: be powered by the input power; control (300) the output of light by the lighting arrangement wherein the processing system is configured to: during a sequence control mode of operation: control (320) the lighting arrangement to output light according to a time-dependent lighting sequence (200); periodically store (330), in a non-volatile memory (120), a progress indicator that indicates a progress through the time-dependent lighting sequence; and responsive to an end of a failure of the input power:- retrieve (370), from the non-volatile memory, the progress indicator; and- resume (380) control of the lighting arrangement, according to the time-dependent lighting sequence, responsive to the progress indicator.

2. The processing system of claim 1, wherein the progress indicator is a time stamp that indicates a time in the time-dependent lighting sequence.

3. The processing system of any one of claims 1 or 2, wherein controlling the lighting arrangement to output light according to the time-dependent lighting sequence comprises controlling the intensity of light output by the lighting arrangement according to the time-dependent lighting sequence.

4. The processing system of any one of claims 1 to 3, wherein: the lighting arrangement comprises an ambient light sensor (170) configured to measure a light level in the vicinity of the lighting arrangement; and the processing system is configured to:receive the light level; compare (310) the light level to a threshold value; and responsive to the light level being below the threshold value, operate in the sequence control mode.

5. The processing system of claim 4, wherein, responsive to the light level being above the threshold value, the processing system is configured to operate in a light suppression mode, wherein the processing system is configured to stop (315) the lighting arrangement outputting light.

6. The processing system of any one of claims 1 to 5, wherein the timedependent lighting sequence comprises a plurality of lighting segments, each lighting segment comprising a segment of time of the time-dependent lighting sequence.

7. The processing system of claim 6, wherein resuming control of the lighting arrangement responsive to the progress indicator comprises identifying a progress segment, being a lighting segment containing the progress indicated by the progress indicator.

8. The processing system of claim 7, wherein resuming control of the lighting arrangement responsive to the progress indicator further comprises determining a target progress point responsive to the progress segment, wherein the target progress point indicates a progress of the time-dependent lighting sequence at which to resume control of the lighting arrangement.

9. The processing system of claim 8, wherein, responsive to the progress segment, the target progress point is set to be equal to either: the progress indicator; or a progress corresponding to a beginning of the lighting segment immediately after the progress segment.

10. The processing system of any one of claims 1 to 9, wherein the processing system receives the progress indicator to store in the non-volatile memory from a tracker, the tracker being configured to define the progress through the time-dependent lighting sequence.

11. A controller (100) for a lighting arrangement (150) comprising: the processing system (110) of any one of claims 1 to 10; the non-volatile memory (120) for storing the progress indicator.

12. The controller of claim 11, wherein the controller is configured to physically connect to the lighting arrangement.

13. The controller of any one of claims 11 or 12, wherein: the non-volatile memory further stores the time-dependent lighting sequence; and the processing system is configured to, prior to controlling the lighting arrangement, retrieve the time-dependent lighting sequence from the non-volatile memory.

14. A method (300) for controlling the output of light by a lighting arrangement (150) configured to be powered by an input power from an external power source (190), the method comprising: controlling (320) the lighting arrangement to output light according to a timedependent lighting sequence (200); periodically storing (330), in a non-volatile memory (120), a progress indicator (390) that indicates a progress through the time-dependent lighting sequence; and responsive to an end of a failure of the input power: retrieving (370), from the non-volatile memory, the progress indicator; and resuming control (380) of the lighting arrangement, according to the time-dependent light sequence, responsive to the progress indicator.

15. A computer program product comprising computer program code means which, when executed on a processing system (110) connected to a lighting arrangement (150), cause the processing system to perform all of the steps of the method (300) according to claim 14.

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